brocade virtual ADX

53-1003247-01

July 2014

Brocade Virtual ADX

Server Load Balancing Guide

Supporting Brocade Virtual ADX version 03.1.00

®

Copyright © 2014 Brocade Communications Systems, Inc. All Rights Reserved.

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Brocade Communications Systems, Inc., in the United States and/or in other countries. Other brands, products, or service names mentioned may be trademarks of their respective owners.

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Document History

Title

Brocade Virtual ADX Server Load

Balancing Guide

Publication number

53-1003247-01

Summary of changes

New document

Date

July 2014

Contents

Preface

Chapter 1

Chapter 2

Document conventions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii

Text formatting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii

Command syntax conventions . . . . . . . . . . . . . . . . . . . . . . . . . . xiv

Notes, cautions, and warnings . . . . . . . . . . . . . . . . . . . . . . . . . . xiv

Brocade resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv

Contacting Brocade Technical Support . . . . . . . . . . . . . . . . . . . . . . . xv

Document feedback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvi

Features

Brocade Virtual ADX Supported Features . . . . . . . . . . . . . . . . . . . . . . 1

Load Balancing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Content Switching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

OpenScript . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

SSL offload for optimization of encrypted traffic. . . . . . . . . . . . . 1

Advanced networking with support for static and dynamic routing2

High availability for active and standby deployments . . . . . . . . . 2

Rate Limiting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Support for Brocade Virtual ADX as a GSLB site for increased availability across datacenters . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Extended hypervisor support for heterogeneous environments. 2

Feature summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Server Load Balancing

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

How SLB works. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Load-balancing predictor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Sticky connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Application port groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Concurrent connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Remote Servers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Direct Server Return . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Configuring basic SLB. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Configuration guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Defining the real servers and real application ports. . . . . . . . . 19

Defining a virtual server (VIP) . . . . . . . . . . . . . . . . . . . . . . . . . . .20

Binding virtual and real servers . . . . . . . . . . . . . . . . . . . . . . . . . 21

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iv

Changing the Load-Balancing Predictor Method . . . . . . . . . . . . . . . 21

Configuring a weighted predictor . . . . . . . . . . . . . . . . . . . . . . . .22

Configuring dynamic weighted predictor . . . . . . . . . . . . . . . . . . 24

Configuring the smooth factor . . . . . . . . . . . . . . . . . . . . . . . . . .25

Real server ports. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Disabling or re-enabling application ports . . . . . . . . . . . . . . . . . 27

Globally disabling application ports . . . . . . . . . . . . . . . . . . . . . .28

Disabling SLB to a server when an application goes down . . .28

Slow-start mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

Enabling or disabling the keepalive health check . . . . . . . . . . .29

Configuring a real port as TCP-only or UDP-only . . . . . . . . . . . .30

Configuring a stateless port . . . . . . . . . . . . . . . . . . . . . . . . . . . .30

Source NAT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Enabling source NAT globally . . . . . . . . . . . . . . . . . . . . . . . . . . .33

Enabling source NAT on a real server. . . . . . . . . . . . . . . . . . . . .33

Configuring a shared source IP address for NAT . . . . . . . . . . . .34

Client subnet based source NAT . . . . . . . . . . . . . . . . . . . . . . . . .34

Enabling port allocation per real server for source NAT IP . . . .35

Remote server . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36

Sticky and concurrent connections . . . . . . . . . . . . . . . . . . . . . . . . . .36

Configuring sticky ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36

Configuring stickiness based on client’s subnet . . . . . . . . . . . . 37

Setting the sticky age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Increasing the sticky-age per VIP longer than 60 minutes . . . .38

Sticky connection return from backup server to primary . . . . .39

Group sticky: Layer 4 SLB to server group . . . . . . . . . . . . . . . . .39

Enabling a concurrent port . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43

Application port grouping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43

Tracking primary ports. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44

Track port group function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44

TCP/UDP application groups configuration example. . . . . . . . . 47

Primary and backup servers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49

Designating a real server as a backup . . . . . . . . . . . . . . . . . . . . 51

Enabling a VIP to use the primary and backup servers. . . . . . . 51

Configuration example. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52

Designating a real server port as a backup . . . . . . . . . . . . . . . .53

Per server based real server backup . . . . . . . . . . . . . . . . . . . . .54

Configuring Direct Server Return . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Configuring L2 Direct Server Return. . . . . . . . . . . . . . . . . . . . . .58

Configuring L3 Direct Server Return. . . . . . . . . . . . . . . . . . . . . .63

Displaying server information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65

Port ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65

Defining a port range. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66

Using a port range under a real server definition . . . . . . . . . . .67

Using a port range under a virtual server definition . . . . . . . . .67

Binding a port range for virtual ports to a real server. . . . . . . .67

Defining port profile for port range. . . . . . . . . . . . . . . . . . . . . . .68

Displaying a list of port ranges . . . . . . . . . . . . . . . . . . . . . . . . . .68


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Multiple port binding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69

Direct binding of multiple ports . . . . . . . . . . . . . . . . . . . . . . . . .70

Port aliases. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .72

Real server groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

Defining a real server group . . . . . . . . . . . . . . . . . . . . . . . . . . . .78

Associating a real server with a real server group. . . . . . . . . . .78

Binding a real server group to a virtual server. . . . . . . . . . . . . .79

Showing real server groups. . . . . . . . . . . . . . . . . . . . . . . . . . . . .79

Disabling or deleting VIPs and real ports . . . . . . . . . . . . . . . . . . . . .79

Disabling VIPs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .79

Disabling a real server. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .80

Disabling or re-enabling an application port . . . . . . . . . . . . . . .80

Globally disabling real and virtual ports. . . . . . . . . . . . . . . . . . .80

Deleting a VIP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Enabling force-delete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .82

Real server shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .83

Port holddown timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .83

Hash-based SLB with server persistence . . . . . . . . . . . . . . . . . . . . .86

Persistent hash table. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .86

Clear vs reassign mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . 87

Enabling persistent hashing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

Enabling the clear-on-change mechanism. . . . . . . . . . . . . . . . . 87

Enabling the reassign-on-change mechanism. . . . . . . . . . . . . .88

Configuring the reassign threshold and duration . . . . . . . . . . .89

Reassignment sequence and example . . . . . . . . . . . . . . . . . . .89

Keeping the persistent hash table unchanged . . . . . . . . . . . . . 91

Real server failure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .92

Displaying persistent hash table entry and statistics . . . . . . . .93

Clearing the hit count for the persistent hash table . . . . . . . . . 94

Clearing the persistent hash table . . . . . . . . . . . . . . . . . . . . . . . 94

Reassigning a persistent hash table entry. . . . . . . . . . . . . . . . . 94

Displaying hash bucket changes . . . . . . . . . . . . . . . . . . . . . . . .95

SLB spoofing configuration and support. . . . . . . . . . . . . . . . . . . . . .95

Policy-based SLB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .96

v

vi

Miscellaneous options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .106

Changing a real server’s IP address . . . . . . . . . . . . . . . . . . . . .106

Adding a description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .107

Configuring a local or remote real server. . . . . . . . . . . . . . . . .107

Configuring a TCP MSS value at the global level . . . . . . . . . . .107

Configuring a TCP MSS value for a virtual server . . . . . . . . . .107

Configuring a TCP MSS value at the virtual server port level .108

Configuring a TCP MSS value at the TCP profile level . . . . . . .108

Support for TCP Window Scale option in TCP header . . . . . . .108

Binding a TCP profile to a virtual port and response rewrite policy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .109

Limiting the maximum number of TCP SYN requests . . . . . . .110

Configuring the maximum connection rate for a real server .110

Configuring the maximum connection rate for a virtual server111

Disabling port translation . . . . . . . . . . . . . . . . . . . . . . . . . . . . .112

Traffic distribution among BPs . . . . . . . . . . . . . . . . . . . . . . . . .112

Including the server client port in hash calculations . . . . . . .113

Sending ICMP Port Unreachable or Destination Unreachable messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .113

Sending a TCP RST to a client that requests unavailable applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .114

Sending a TCP RST when TCP session entry ages out . . . . . .114

Disabling TCP RST message when a real server goes down during an open session . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .115

No TCP RST response to non-SYN first packet of a TCP flow .115

Decrement counters in deletion queue . . . . . . . . . . . . . . . . . .115

Optimized fast-path SLB processing. . . . . . . . . . . . . . . . . . . . .116

Configuring TCP fast aging . . . . . . . . . . . . . . . . . . . . . . . . . . . .116

Server opt-enable-route recalculation . . . . . . . . . . . . . . . . . . .117

Enabling use of the client MAC address. . . . . . . . . . . . . . . . . .117

Enabling transparent VIP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .117

Enabling SYN ACK threshold . . . . . . . . . . . . . . . . . . . . . . . . . . .118

Replacing the source MAC address of the packet. . . . . . . . . .118

Cloning real servers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .118

Configuring a host range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .119

Unbinding all application ports from virtual servers . . . . . . . .119

Identifying VIP port as TCP only or UDP only . . . . . . . . . . . . . .119

Enabling fast aging for UDP sessions. . . . . . . . . . . . . . . . . . . .120

Enabling normal UDP aging for DNS and RADIUS . . . . . . . . . .121

Setting TCP and UDP ages for VIPs. . . . . . . . . . . . . . . . . . . . . .121

Configuring session aging behavior . . . . . . . . . . . . . . . . . . . . .122

Configuring DNS CPU-based throttling . . . . . . . . . . . . . . . . . . .122

Configuring UDP DNS count connection . . . . . . . . . . . . . . . . .123

Dedicated next hop per VIP for reverse SLB traffic . . . . . . . . .123

VIP route health injection . . . . . . . . . . . . . . . . . . . . . . . . . . . . .124

VIP RHI with dangling subnets . . . . . . . . . . . . . . . . . . . . . . . . .130

VIP RHI and high availability topologies . . . . . . . . . . . . . . . . . .132

Application-specific SLB considerations . . . . . . . . . . . . . . . . . . . . .150

RTSP server load balancing . . . . . . . . . . . . . . . . . . . . . . . . . . .150

Deletion of UDP data session along with TCP control session for RTSP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .150

TFTP load balancing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .150


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Chapter 3

Chapter 4

Show and debug commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .151

Displaying the BP distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . .151

Stateless Server Load Balancing

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .153

Stateless TCP and UDP ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .153

How the Brocade Virtual ADX selects a real server for a stateless port. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .154

Configuring the stateless hash table size . . . . . . . . . . . . . . . .155

Configuring a stateless application port . . . . . . . . . . . . . . . . .155

Fragmentation support in the stateless mode. . . . . . . . . . . . .157

Health Checks

Health checks overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .159

Layer 3 health checks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .159

Disabling Layer 3 health checks . . . . . . . . . . . . . . . . . . . . . . . .160

Modifying the ping interval and ping retries. . . . . . . . . . . . . . .161

Setting the Periodic ARP Interval . . . . . . . . . . . . . . . . . . . . . . .161


Performing Layer 4 UDP keepalive health checks for the DNS port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .163


Application ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .167

DNS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .168

FTP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .169

HTTP (status code). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .169

HTTP (content verification) . . . . . . . . . . . . . . . . . . . . . . . . . . . .170

Scripted (content verification for unknown ports) . . . . . . . . . .170

IMAP4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171

LDAP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171

MMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .172

NNTP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .173

PNM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .173

POP3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .173

RADIUS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174

RTSP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174

SMTP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .175

SSL (complete) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .175

SSL (simple) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176

Telnet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176

Port-specific settings for Layer 7 health checks . . . . . . . . . . . 176

Layer 7 health check for an unknown port . . . . . . . . . . . . . . .183

Server and application port states . . . . . . . . . . . . . . . . . . . . . . . . .184

Server states . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .184

Application port states. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .185


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Port profiles and attributes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .187

Configuring a port profile. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .188

Configuring port profile attributes . . . . . . . . . . . . . . . . . . . . . .189

Port policy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .193

Port policies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .193

Configuring a port policy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .193

Binding the policy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .195

Configuring a keepalive interval under a port policy . . . . . . . .196

Health check policy for VIP port . . . . . . . . . . . . . . . . . . . . . . . .197

Element health checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .198

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .198

Configuring element-action expressions . . . . . . . . . . . . . . . . .198

Attaching a health-check policy to an application port on a server . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .205

Displaying health-check policies and their status . . . . . . . . . .206

Displaying health-check policy statistics . . . . . . . . . . . . . . . . .207

Clearing health-check policy statistics . . . . . . . . . . . . . . . . . . .207

Health check with content match . . . . . . . . . . . . . . . . . . . . . . . . . .208

Content match for HTTP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .208

Content match for non-HTTP ports . . . . . . . . . . . . . . . . . . . . . .211

Binary scripted health check. . . . . . . . . . . . . . . . . . . . . . . . . . .214

Boolean health checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .216

Boolean health-check policies . . . . . . . . . . . . . . . . . . . . . . . . .216

Health-check policy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .216

Configuring boolean health check . . . . . . . . . . . . . . . . . . . . . . 217

Miscellaneous health check settings . . . . . . . . . . . . . . . . . . . . . . .219

Basing an alias port’s health on the health of its master port. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .219

Basing a port’s health on the health of another port . . . . . . .220

Reassign threshold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .220

Globally disabling all health-check policies . . . . . . . . . . . . . . .222

Health checking for real servers in other subnets. . . . . . . . . .222

Best path to a remote server . . . . . . . . . . . . . . . . . . . . . . . . . .222

Handling traffic initiated from remote server. . . . . . . . . . . . . .223

Health check of multiple websites on the same real server. .224

Minimum healthy real servers under VIP port . . . . . . . . . . . . .225

Server port bring-up enhancement . . . . . . . . . . . . . . . . . . . . .225

Slow-start mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .225

FIN close for server health check . . . . . . . . . . . . . . . . . . . . . . .233

Health-check state. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .233

Enhanced server bringup . . . . . . . . . . . . . . . . . . . . . . . . . . . . .234

Track-Port support under real server for health checks . . . . .234

Sample show commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .235

Syslog for health status change . . . . . . . . . . . . . . . . . . . . . . . .235

Session table parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . .236

Configuring TCP age. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .239

Configuring UDP age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .239

Setting the clock scale. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .240

Syslog for session table entries . . . . . . . . . . . . . . . . . . . . . . . .240


53-1003247-01

Chapter 5 Layer 7 Content Switching

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .243

Layer 7 content switching. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .243

Enabling CSW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .244

Specifying scan depth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .244

Enabling CSW load balance . . . . . . . . . . . . . . . . . . . . . . . . . . .244

CSW rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .245

CSW policies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .250

Explanation of offsets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .265

Sample configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .266

CSW topology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .267

Request delete configuration . . . . . . . . . . . . . . . . . . . . . . . . . .267

Layer 7 content switching on HTTP response . . . . . . . . . . . . . . . . . 271

Response header rewrite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271

Configuring HTTP header response rewrite . . . . . . . . . . . . . . . 271

Using multiple cookies under virtual server port . . . . . . . . . . . . . .273

Configuring multiple unique cookie insertion with cookie path. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .273

Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 274

Server passive cookie persistence . . . . . . . . . . . . . . . . . . . . . . . . .275

Configuring server passive cookie persistence . . . . . . . . . . . . 276

Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .278

Server and server port persistence with CSW nested rules. . . . . .279

Configuring server and server port persistence with

CSW nested rules. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .279

Configuring persist on the nested rule . . . . . . . . . . . . . . . . . . .280

Configuring persist on the real port . . . . . . . . . . . . . . . . . . . . .280

Displaying CSW information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .282

Displaying the statistics for all HTTP content rewrites . . . . . .287

Displaying Layer 7 switching statistics . . . . . . . . . . . . . . . . . . .288

Usage guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .289

Support for large GET requests. . . . . . . . . . . . . . . . . . . . . . . . .290

Miscellaneous Layer 7 switching configurations . . . . . . . . . . . . . .290

Cleaning up all hash buckets . . . . . . . . . . . . . . . . . . . . . . . . . .290

Layer 7 content buffering options. . . . . . . . . . . . . . . . . . . . . . .290

HTTP 1.1 support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .291

Layer 7 CSW pseudo stack client-side retransmission handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .295

Layer 7 CSW pseudo stack server-side TCP packet out-of-sequence handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . .297

Setting up SSL session ID switching . . . . . . . . . . . . . . . . . . . . . . . .298

Configuration Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .301

Command reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .302

rewrite request-delete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .302

rewrite request-insert . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .303

rewrite request-replace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .303


53-1003247-01 ix

x

Chapter 6

Chapter 7

Chapter 8

Hot Standby High Availability

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .305

Hot Standby HA protocol operations. . . . . . . . . . . . . . . . . . . . .306

Hot Standby HA configuration modes . . . . . . . . . . . . . . . . . . . . . . .307

Non-Promiscuous mode with default non-shared MAC option307

Promiscuous mode with shared MAC option . . . . . . . . . . . . . .308

Hot Standby HA Configuration Considerations . . . . . . . . . . . . . . . .308

Configuring standard Hot Standby HA . . . . . . . . . . . . . . . . . . . . . . .308

Additional configuration variations . . . . . . . . . . . . . . . . . . . . . . . . .312

VIP and servers in different subnets . . . . . . . . . . . . . . . . . . . .312

Source-NAT in Hot Standby . . . . . . . . . . . . . . . . . . . . . . . . . . . .314

Configuring additional HA parameters . . . . . . . . . . . . . . . . . . . . . .314

Configuring a backup group ID . . . . . . . . . . . . . . . . . . . . . . . . .315

Setting the backup timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .315

Enabling backup preference . . . . . . . . . . . . . . . . . . . . . . . . . . .316

Configuring failover based on active VIP count . . . . . . . . . . . .316

Configuring failover based on the number of active virtual ports317

Delayed failover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .318

Configuring a Brocade Virtual ADX to remain in standby state318

Configuring the forwarding of synchronizing messages . . . . . . . . .319

Configuring synchronization with HA . . . . . . . . . . . . . . . . . . . . . . . .319

Hot-standby HA with routing protocols. . . . . . . . . . . . . . . . . . . . . . .319

Tie state of virtual link and HA physical link using health checks321

SIP Server Load Balancing

SIP overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .323

SIP packet flow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .324

SIP client registration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .326

SIP terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .326

SIP message headers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .327

SIP SLB and call persistence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .328

SIP and call persistence specifications . . . . . . . . . . . . . . . . . .329

Sample deployment topologies. . . . . . . . . . . . . . . . . . . . . . . . .330

SIP server health monitoring. . . . . . . . . . . . . . . . . . . . . . . . . . .333

Configuring SIP SLB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .333

SIP SLB over UDP (Stateless SLB mode) . . . . . . . . . . . . . . . . .333

SIP SLB over UDP (stateful SLB mode). . . . . . . . . . . . . . . . . . .338

Debug commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .340

SIP SLB command reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .343

Real server configuration mode . . . . . . . . . . . . . . . . . . . . . . . .343

Virtual server configuration mode . . . . . . . . . . . . . . . . . . . . . .343

Sample configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .343

IPv6 Support for Server Load Balancing

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .345


53-1003247-01

Appendix A

Appendix B

Defining IPv6 real servers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .346

Defining IPv6 virtual servers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .346

Defining port characteristics using port profile . . . . . . . . . . . . . . .346

Defining IP routes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .346

VLAN and tagging definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .347

Miscellaneous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .347

Saving the configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .347

IPv6 configuration example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .347

Server-specific Loopback Configurations

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .349

Solaris . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .349

Linux. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .349

Windows NT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .350

Manual installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .350

Unattended installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .350

Deleting the unwanted routes. . . . . . . . . . . . . . . . . . . . . . . . . .351

SLB Show and Debug Commands

Using show source-ip source ip

[ real-server ip | all] . . . . . . . . . . . .355

Using the show session all command . . . . . . . . . . . . . . . . . . . . . . .356

Using the source-ip-debug command . . . . . . . . . . . . . . . . . . . . . . .357

Using the debug filter command . . . . . . . . . . . . . . . . . . . . . . . . . . .357

Using the packet capture utility . . . . . . . . . . . . . . . . . . . . . . . .357

"debug filter" example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .363

Saving captured packets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .367

Helpful tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .368

Displaying global Layer 4 Brocade Virtual ADX configuration . . . .368

Displaying real server information and statistics . . . . . . . . . . . . . . 371

Using the show server real command . . . . . . . . . . . . . . . . . . . 371

Using the show server real detail command . . . . . . . . . . . . . .373

Displaying real server keepalive statistics . . . . . . . . . . . . . . . . 376

Displaying real server connections per second statistics . . . . 376

Displaying virtual server information and statistics . . . . . . . . . . . .377

Displaying a list of failed servers . . . . . . . . . . . . . . . . . . . . . . . . . . .380

Displaying a list of failed ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . .380

Displaying port-binding information. . . . . . . . . . . . . . . . . . . . . . . . .381

Using the “show server bind” command . . . . . . . . . . . . . . . . .381

Using the “show server session” command. . . . . . . . . . . . . . .381

Displaying packet traffic statistics . . . . . . . . . . . . . . . . . . . . . . . . . .384


53-1003247-01 xi

Appendix C

Displaying configuration information. . . . . . . . . . . . . . . . . . . . . . . .386

Showing aggregate health of tracked ports . . . . . . . . . . . . . . .386

Auto repeat of show command output . . . . . . . . . . . . . . . . . . .387

Clearing all session table entries . . . . . . . . . . . . . . . . . . . . . . .387

Clearing the connections counter. . . . . . . . . . . . . . . . . . . . . . .388

Acknowledgements

OpenSSL license . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .389

Cryptographic software. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .390

Original SSLeay License . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .390

xii Brocade Virtual ADX Server Load Balancing Guide

53-1003247-01

Preface

Document conventions

This section describes text formatting conventions and important notice formats that may be used in this document.

Text formatting

The following text formatting conventions may be used in the flow of the text to highlight specific words or phrases.

Format bold text italic text code

Description

Identifies command names

Identifies keywords

Identifies the names of user-manipulated GUI elements

Identifies text to enter at the GUI or CLI

Provides emphasis

Identifies variables and modifiers

Identifies paths and Internet addresses

Identifies document titles

Identifies CLI output

Identifies command syntax examples


53-1003247-01 xiii

xiv

Command syntax conventions

...

\

Convention bold text italic text

[ ]

{ x | y |z } x | y

< >

Description

Identifies command names, keywords, and command options.

Identifies variables.

Syntax components displayed within square brackets are optional.

A choice of required parameters is enclosed in curly braces separated byvertical bars. You must select one.

A vertical bar separates mutually exclusive elements.

Nonprinting characters, for example, passwords, are enclosed in angle brackets.

Repeat the previous element. For example, member [member...].

Indicates a “soft” line break in command examples. If a backslash separates two lines of a command input, enter the entire command at the prompt without the backslash.

Notes, cautions, and warnings

The following notices and statements may be used in this document. They are listed below in order of increasing severity of potential hazards.

NOTE

A note provides a tip, guidance or advice, emphasizes important information, or provides a reference to related information.

ATTENTION

An Attention statement indicates a stronger note, for example, to alert you when traffic might be interrupted or the device might reboot.

CAUTION

A Caution statement alerts you to situations that can be potentially hazardous to you or cause damage to hardware, firmware, software, or data.

DANGER

A Danger statement indicates conditions or situations that can be potentially lethal or extremely hazardous to you. Safety labels are also attached directly to products to warn of these conditions or situations.


53-1003247-01

Brocade resources

To get up-to-the-minute information, go to http://my.brocade.com

to register at no cost for a user ID and password.

Release notes are available at http://my.brocade.com

.

White papers, online demonstrations, and data sheets are available through the Brocade website at: http://www.brocade.com/products-solutions/products/index.page

Select Application Delivery Switches on this page to navigate to the relevant product information.

Contacting Brocade Technical Support

As a Brocade customer, you can contact Brocade Technical Support 24x7 online, by telephone, or by e-mail. Brocade OEM customers contact their OEM/Solutions provider.

For product support information and the latest information on contacting the Technical Assistance

Center, go to http://www.brocade.com/services-support/index.html

If you have purchased Brocade product support directly from Brocade, use one of the following methods to contact the Brocade Technical Assistance Center 24x7.

Online

Preferred method of contact for non-urgent issues:

• My Cases through

MyBrocade

• Software downloads & licensing tools

• Knowledge Base

Telephone

Required for Sev 1-Critical and

Sev 2-High issues:

• Continental US:

1-800-752-8061

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FIBREE (+800 28 34 27

33)

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+1-408-333-6061

• Toll-free numbers are available in many countries.

Email support@brocade.com

Please include:

• Problem summary

• Serial number

• Installation details

• Environment description

If you have purchased Brocade product support from a Brocade OEM/Solution Provider, contact your OEM/Solution Provider for all of your product support needs.

• OEM/Solution Providers are trained and certified by Brocade to support Brocade® products.

• Brocade provides backline support for issues that cannot be resolved by the OEM/Solution

Provider.


53-1003247-01 xv

Document feedback

• Brocade Supplemental Support augments your existing OEM support contract, providing direct access to Brocade expertise. For more information, contact Brocade or your OEM.

• For questions regarding service levels and response times, contact your OEM/Solution

Provider.

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Quality is our first concern at Brocade and we have made every effort to ensure the accuracy and completeness of this document. However, if you find an error or an omission, or you think that a topic needs further development, we want to hear from you. You can provide feedback in two ways:

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xvi Brocade Virtual ADX Server Load Balancing Guide

53-1003247-01

Features

Chapter

1

Brocade Virtual ADX Supported Features

The Brocade Virtual ADX supports all of the essential features for ensuring the optimized delivery of application traffic.

Load Balancing

The Brocade Virtual ADX enables the efficient distribution of traffic among application and infrastructure servers. In this capacity, the system can load balance traffic based on a number of different characteristics including server connection load, server resources such as CPU and memory, application response time, and pre-assigned server weights while ensuring session stickiness on selected servers when required. Together, these capabilities combined with a rich set of server monitoring capabilities serve to ensure an optimal application experience.

Content Switching

To manage traffic based on deeper application intelligence, the Brocade Virtual ADX can determine the server that is best suited to respond to different traffic types and direct traffic accordingly.

Traffic policies can be configured based on both URL and HTTP header information allowing traffic to be distributed based on user information and device characteristics as well as the content they're requesting.

OpenScript

The Brocade Virtual ADX includes a powerful application scripting engine for developing real-time application services - allowing for the manipulation of transaction responses based on information in the request and vice versa enabling more advanced traffic-handling. The small footprint of the

OpenScript engine increases the number of scripts that can run simultaneously on the system. And to ensure optimal performance, the system can estimate the performance of custom scripts without requiring the need for live traffic.

SSL offload for optimization of encrypted traffic

The Brocade Virtual ADX supports the offloading of CPU-intensive SSL negotiation and connection management from application servers, to improve response times. This is achieved by decrypting incoming client requests, processing the traffic and load balancing each request before re-encrypting the response on the return path.


53-1003247-01

1

2

1

Brocade Virtual ADX Supported Features

Advanced networking with support for static and dynamic routing

The system supports both static and dynamic routing (for OSPF, BGP and RIP protocols) as well as route health injection (RHI). This combination of features allows administrators to configure the system so that an upstream router can pick the optimal route for reaching a virtual server.

High availability for active and standby deployments

To ensure undisrupted transaction processing the Brocade Virtual ADX can be deployed as an active-standby pair. In this configuration two ADX devices can be configured so that one device is set up to actively manage traffic while the other acts as a standby device and is positioned to take over in the event of a failure. When a failover occurs the active device will transition control to the standby device effectively switching the roles of the two devices. The result is a more robust load balancing topology.

Rate Limiting

For added control the Brocade Virtual ADX now supports rate limiting at the port level allowing administrators to define the maximum throughput for a given port. The system then monitors the rate of traffic passing through that port and takes preventive action, in real time, based on the predefined traffic rate.

Support for Brocade Virtual ADX as a GSLB site for increased availability across datacenters

Global Server Load Balancing (GSLB) is a common deployment topology used to manage traffic across one or more datacenters or sites. These sites are often distributed geographically. In this release of the Brocade Virtual ADX, a Brocade GSLB controller can now recognize a Brocade Virtual

ADX instance as participating in a GSLB site, further increasing availability of the entire application.

Extended hypervisor support for heterogeneous environments

The Brocade Virtual ADX can now be deployed on a variety of third party hypervisors including

VMware ESX, Citrix XenServer and KVM. Supported releases are listed below:

• VMware Hypervisor ESX version 4.0 or later and VMware vSphere Client version 4.0 or later

• KVM host 0.9.0 or higher

• Citrix XenServer hypervisor version 6.2.0 or later and Citrix XenCenter client version 6.2 or later


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Feature summary

The following tables lists the supported features and related documentation for the Brocade Virtual

ADX releases.

TABLE 1

Category

Supported features for Brocade Virtual ADX version 03.1.00

Feature Document

Networking

Global Server Load Balancing

Licensing

Security


Rate Limiting and Counters at VE or VIP Brocade Virtual ADX Switching and

Routing Guide

GSLB controller Brocade Virtual ADX Global Server

Load Balancing Guide

License SKUs Brocade Virtual ADX Licensing

Guide

Brocade Virtual ADX Installation

Guide Single IP address for management port

TCP checksum offload for Xen or KVM

Upgrade process

Additional interfaces

System-max based on memory Brocade Virtual ADX Licensing

Guide and

Brocade Virtual ADX Switching and

Routing Guide

Brocade Virtual ADX Security Guide ACL

DDoS

SYN-Proxy

TRL

VIP Max-Conn rate

VIP prioritization

SIP Brocade Virtual ADX Server Load

Balancing Guide

TABLE 2

Category

Networking


Feature Document

Content Switching

Health Monitoring

IPv6

Dynamic routing (for OSPF, BGP and RIP protocols)

Rate limiting at the port level

Route health injection (RHI)

SSL session ID switching

Health Check for non-HTTP protocols

(RTSP and MMS)


Routing Guide


Routing Guide


Routing Guide


Balancing Guide


Balancing Guide


Balancing Guide


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Feature summary

TABLE 2

Category

Supported features for Brocade Virtual ADX version 03.0.00 (Continued)

Feature Document

High Availability Hot Standby configuration Brocade Virtual ADX Server Load

Balancing Guide

Security

GSLB

XML

SSL Offload, SSL Termination on

Brocade Virtual ADX

DNS DPI

IP NAT

GSLB site

Config templates (XML, CLI, and GUI)

Brocade Virtual ADX Installation

Guide

Brocade Virtual ADX Security Guide and Brocade Virtual ADX Server


Brocade Virtual ADX Security Guide

Brocade Virtual ADX Security Guide

Brocade Virtual ADX Global Server


Brocade Virtual ADX Graphic User

Interface Guide

TABLE 3

Category

Networking

Load Balancing

Content Switching

OpenScript


Feature Document

Health Monitoring

Static Routing

VLANs and VLAN tagging

IPv4

Server Load Balancing for TCP and UDP protocols

Policy-based Server Load Balancing

(PBSLB)

Source NAT

Direct Server Return (DSR)

Content Switching for HTTP protocol

Content Scripting for HTTP protocol

Health Check for TCP, UDP, and HTTP protocols


Routing Guide


Routing Guide


Routing Guide


Balancing Guide


Balancing Guide


Balancing Guide


Balancing Guide


Balancing Guide

Brocade Virtual ADX OpenScript

Programmer’s Guide and

Brocade Virtual ADX OpenScript

Programmer’s Guide


Balancing Guide


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TABLE 3

Category

Supported features for Brocade Virtual ADX version 02.0.00 (Continued)

Feature Document

High Availability Additional variations, IPv4 to IPv6 gateway high availability support


Balancing Guide

System Management All system management including

SOAP/XML API for supported features,

CLI, GUI, syslog, Telnet, SCP, SNTP,

SNMP, AAA, packet filter etc.)

Brocade ADX Administration Guide and Brocade ADX Graphical User

Interface Guide


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Feature summary

6 Brocade Virtual ADX Server Load Balancing Guide

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Chapter

2

Overview

The Brocade Virtual ADX Application Delivery Switch (Brocade Virtual ADX) helps ease the administration of TCP-based or UDP-based applications. They provide server load balancing (SLB) for the application servers, help offload CPU-intensive tasks from the application servers, and provide added security to the server farm.

In Figure 1 , the system administrator has greater flexibility in managing application server resources. By using a Brocade Virtual ADX, the system administrator can seamlessly add or remove the application servers (real servers) and handle the changing traffic requirements without disrupting service to the end-users. The application clients access the virtual IP address or VIP

(virtual server) that is hosted by the Brocade Virtual ADX.

In addition to offering increased control over server resources, the Brocade Virtual ADX offers numerous other functions, such as application health checks, server offload, and greater security.

FIGURE 1 Single virtual IP address mapped to multiple real servers

The server load balancing (SLB) requires associations between the application servers (real servers) and the virtual server (VIP). The associations are done by binding TCP or UDP ports on the real servers with TCP or UDP ports on the virtual server. When a client sends a TCP or UDP request to an application port defined under the virtual server, the Brocade Virtual ADX identifies one of the back-end application servers based on the configured load balancing method and forwards the client request to it. The client is completely unaware of this traffic distribution, but observes increased availability, faster response time and better throughput. The Brocade Virtual ADX can be configured to host multiple application services such as web (HTTP), FTP, or DNS under a single virtual server.


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Overview

In Figure 1 , an application administrator has established a web site www.example7.com. This web site is mapped to the virtual server (VIP 10.95.55.1) that is hosted on the Brocade Virtual ADX. All queries made to this web site arrive at the virtual server. The Brocade Virtual ADX then distributes these queries among the four back-end application servers. The actual addresses of these four real web servers remain unknown and unseen to the end users. They observe only one IP address, which is the VIP address for the web service.

How SLB works

A Brocade Virtual ADX running SLB software establishes a virtual server that acts as a front end to physical servers, distributing user service requests among active real servers. SLB packet processing is based on the Network Address Translation (NAT) method. Packets received by the virtual server IP address are translated into the real physical IP address based on the configured distribution metric (for example, “round robin”) and sent to a real server. Packets returned by the real server for the end user are translated by SLB so that the source address is that of the virtual server instead of the real server.

Port translation is not performed for any virtual port that is bound to a default virtual port.

Load-balancing predictor

The load-balancing predictor is an algorithm that determines how traffic is distributed among the application servers (real servers).

It is possible to fine-tune traffic distribution among servers by selecting one of the following predictors:

Least connections predictor

Sends the request to the real server that currently has the fewest active connections with clients.

For sites where a number of servers have similar performance, the least connections option smooths distribution if a server gets bogged down. For sites where the capacity of various servers varies greatly, the least connections option maintains an equal number of connections among all servers. Servers that are capable of processing and terminating connections faster then receive more connections than slower servers over time.

NOTE

The Least Connections predictor does not depend on the number of connections to individual ports on a real server but instead depends on the total number of active connections to the server.

The Least Connections predictor can be applied globally to the entire Brocade Virtual ADX or locally

per virtual server as described in “Changing the Load-Balancing Predictor Method” on page 21.

Round Robin predictor

Directs the service request to the next server, and treats all servers equally regardless of the number of connections. For example, in a configuration of four servers, the first request is sent to

Server1, the second request is sent to Server2, the third is sent to Server3, and so on. After all servers in the list have received one request, assignment begins with Server1 again. If a server fails, SLB avoids sending connections to that server and selects the next server instead. The Round

Robin predictor can be applied globally to apply for the entire Brocade Virtual ADX or locally per-virtual server as described in

“Changing the Load-Balancing Predictor Method” on page 21.


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Weighted Round Robin predictor

Like the Round Robin predictor, the Weighted Round Robin predictor treats all servers equally regardless of the number of connections or response time. It does however use a configured weight value that determines the number of times within a sequence that the each server is selected in relationship to the weighted values of other servers. For example, in a simple configuration with two servers where the first server has a weight of 4 and the second server has a weight of 2, the sequence of selection would occur as described in the following:

1. The first request is sent to Server1.

2. The second request is sent to Server2.

3. The third request is sent to Server1.

4. The fourth request is sent to Server2.

5. The fifth request is sent to Server1.

6. The sixth request is sent to Server1.

Notice that over this cycle of server connections, Server1, which had a weight of 4, was accessed four times and Server2, which had a weight of 2, was accessed only twice.

This cycle will repeat as long as this predictor is in use.

The Weighted Round Robin predictor can be applied globally to the entire Brocade Virtual ADX or

locally per virtual server as described in “Changing the Load-Balancing Predictor Method” on page 21.

Static Weighted Round Robin predictor

The Static Weighted Round Robin predictor makes its server selections exactly like the Weighted

Round Robin predictor, however, it does not distribute the load to available barrel processors (BPs) within the Brocade Virtual ADX. Consequently, server selection can be concurrent to better utilize your system capacity. The following description provides a simple example:

The Brocade Virtual ADX has the following configuration:

• Two BPs are enabled and in an operating state

• Three servers are connected: Server1 with a weight of 3, Server2 with a weight of 2, Server3 with a weight of 1

Distribution will occur as described in the following.

For BP1








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Overview

For BP2







Notice that this sequence for each pair of servers is exactly the same as described in the example for the Weighted Round Robin predictor. The only difference is that these selections are being performed concurrently on each of the BPs which allows each server to be selected more frequently. This method scales to accommodate the number of processors present in the system.

The Static Weighted Round Robin predictor can be applied globally to the entire Brocade Virtual

ADX or locally per virtual server as described in


NOTE

To use the static weighted round robin predictor for Layer 7, a server group must be defined for bound real servers. When all of the server’s fail to meet the Layer-7 selection criteria, load balancing will not fall back to Layer-4 server load balancing.

Weighted and Enhanced Weighted load balancing

Assigns a performance weight to each server. Weighted and Enhanced load balancing are similar to least connections, except that servers with a higher weight value receive a larger percentage of connections at a time. You can assign a weight to each real server, and that weight determines the percentage of the current connections that are given to each server.

NOTE it is required that you configure a weight for any real server that is bound to a VIP that is expected to load balance based on a weighted or enhanced weighted predictor

For example, in a configuration with five servers of various weights, the percentage of connections is calculated as follows:

• Weight server1 = 7





• Total weight of all servers = 24

The result is that Server1 gets 7/24 of the current number of connections, Server2 gets 8/24,

Server3 gets 2/24, and so on. If a new server, Server6, is added with a weight of 10, the new server gets 10/34.


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If you set the weight so that your fastest server gets 50 percent of the connections, it will get 50 percent of the connections at a given time. Because the server is faster than others, it can complete more than 50 percent of the total connections overall, because it services the connections at a higher rate. Therefore, the weight is not a fixed ratio but adjusts to server capacity over time.

The difference between weighted and enhanced-weighted load-balancing is the method of distributing the traffic after it is assigned.

Connections

1

1

1

2

2

2

0

1

1

1

0

0

0

0

0

Connection assignments with weighted predictor for weighted load-balancing

In weighted load-balancing, the traffic is distributed by allocating all of the required connections sequentially to the server with the greatest weight first and then to the server with the next greatest weight, followed by the server with the next greatest weight and so on, until all servers have received their share of connections. The process then repeats.

Table 4

shows the distribution pattern for Weighted Load-Balancing in an example configuration with three real servers, A, B, and C. Real Server A has a weight of 1, Real Server B has a weight of

2, and Real Server C has a weight of 3. The numbers in bold indicate which server receives the new connection. When the weighted predictor is configured, connections are assigned as shown in

Table 4

.

TABLE 4

Real Server A

SLB with the weighted predictor

Real Server B weight = 1 weight = 2

Real Server C weight = 3

Server load a

0 / 1 = 0

0 / 1 = 0

0 / 1 = 0

0 / 1 = 0

0 / 1 = 0

0 / 1 = 0

1 / 1 = 1

1 / 1 = 1

1 / 1 = 1

1 / 1 = 1

1 / 1 = 1

1 / 1 = 1

2 / 1 = 2

2 / 1 = 2

2 / 1 = 2

Connections

2

3

4

4

4

4

2

2

2

2

0

0

1

0

0

Server load

0 / 2 = 0

0 / 2 = 0

0 / 2 = 0

0 / 2 = 0

1 / 2 = 0

2 / 2 = 1

2 / 2 = 1

2 / 2 = 1

2 / 2 = 1

2 / 2 = 1

3 / 2 = 1

4 / 2 = 2

4 / 2 = 2

4 / 2 = 2

4 / 2 = 2

Connections

6

6

6

6

7

8

3

3

4

5

2

3

3

0

1

Server load

0 / 3 = 0

1 / 3 = 0

2 / 3 = 0

3 / 3 = 1

3 / 3 = 1

3 / 3 = 1

3 / 3 = 1

4 / 3 = 1

5 / 3 = 1

6 / 3 = 2

6 / 3 = 2

6 / 3 = 2

6 / 3 = 2

7 / 3 = 2

8 / 3 = 2 a.

For the weighted predictor, the server load is calculated as connections divided by server weight = server load.

Fractional remainders are rounded down. If there is a tie, the server with the highest weight receives the connection


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Overview

Connection assignments with enhanced weighted predictor for enhanced weighted load-balancing

In enhanced weighted load-balancing, the traffic is distributed in the same proportions as in weighted load-balancing, but the order of distribution is different. With enhanced weighted load-balancing, the real server with the greatest weight is allocated a connection first, but then the next connection is allocated to the real server with the next greatest weight, and then to the server with the next greatest weight on-down-the-line, until all servers have received their first connection.

The process repeats with each real server getting a connection in sequence until each real server has connections equal to its assigned weight.

Table 5

shows the distribution pattern for Enhanced Weighted Load-Balancing in an example configuration with three real servers, A, B, and C. Real Server A has a weight of 1, Real Server B has a weight of 2, and Real Server C has a weight of 3. The numbers in bold indicate which server receives the new connection. When the weighted predictor is configured, connections are assigned

as shown in Table 5

.

TABLE 5

Real Server A

SLB with the enhanced weighted predictor

Real Server B weight = 2

Real Server C weight = 3 weight = 1

Connections Server load a

2

2

2

2

2

2

1

1

1

1

0

1

1

0

0

0 x 6 / 1 = 0

0 x 6 / 1 = 0

0 x 6 / 1 = 0

1 x 6 / 1 = 6

1 x 6 / 1 = 6

1 x 6 / 1 = 6

1 x 6 / 1 = 6

1 x 6 / 1 = 6

1 x 6 / 1 = 6

2 x 6 / 1 = 12

2 x 6 / 1 = 12

2 x 6 / 1 = 12

2 x 6 / 1 = 12

2 x 6 / 1 = 12

2 x 6 / 1 = 12

Connections Server load

3

3

4

4

4

5

2

2

2

3

1

1

1

0

0

0 x 6 / 2 = 0

0 x 6 / 2 = 0

1 x 6 / 2 = 3

1 x 6 / 2 = 3

1 x 6 / 2 = 3

2 x 6 / 2 = 6

2 x 6 / 2 = 6

2 x 6 / 2 = 6

3 x 6 / 2 = 9

3 x 6 / 2 = 9

3 x 6 / 2 = 9

4 x 6 / 2 = 12

4 x 6 / 2 = 12

4 x 6 / 2 = 12

5 x 6 / 2 = 15

Connections Server load

4

5

5

6

7

7

2

3

4

4

1

1

2

0

1

0 x 6 / 3 = 0

1 x 6 / 3 = 2

1 x 6 / 3 = 2

1 x 6 / 3 = 2

2 x 6 / 3 = 4

2 x 6 / 3 = 4

3 x 6 / 3 = 6

4 x 6 / 3 = 8

4 x 6 / 3 = 8

4 x 6 / 3 = 8

5 x 6 / 3 = 10

5 x 6 / 3 = 10

6 x 6 / 3 = 12

7 x 6 / 3 = 14

7 x 6 / 3 = 14 a.

For the enhanced weighted predictor, the server load is calculated as connections x [combined weights / server weight] = server load. Fractional remainders are rounded down. If there is a tie, the server with the highest weight receives the connection.

Weighted and Enhanced Weighted predictors can be enabled as described in: “Changing the

Load-Balancing Predictor Method” on page 21.


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Dynamic weighted predictor

The Brocade Virtual ADX provides a dynamic weighted predictor that enables it to make load balancing decisions using real time server resource usage information, such as CPU utilization and memory consumption. The Brocade Virtual ADX retrieves this information (through the SNMP protocol) from MIBs available on the application servers.

To achieve this capability, a software process in the Brocade Virtual ADX, named SNMP manager

(also called SNMP client) is used. This process is different from the SNMP agent process (a.k.a.

SNMP server process) on the Brocade Virtual ADX. A Brocade Virtual ADX can be configured as both SNMP agent (that allows management of the Brocade Virtual ADX through Network

Management System), and SNMP manager (that facilitates the new SNMP based predictor method). In addition, all the real servers must run the SNMP agent daemon and support MIBs that can be queried by the SNMP manager of the Brocade Virtual ADX.

You can fine-tune how traffic is distributed across these real servers by enabling Dynamic Weighted

Predictor on the Brocade Virtual ADX.

The Dynamic Weighted predictors can be applied globally to apply for the entire Brocade Virtual


“Changing the Load-Balancing Predictor Method”

on page 21 and “Configuring dynamic weighted predictor” on page 24.

NOTE

The global command snmp-server is enabled by default and this command must not be removed if the dynamic weighted predictor is configured. If this command is removed, then the Brocade Virtual

ADX will stop listening on the UDP port 161 and drop SNMP responses from the real servers that are used for this predictor.

Dynamic-weighted Direct

The SNMP response from each server is regarded as a performance weight. The displayed SNMP

Weight under “show server real” is the direct weight from the SNMP response. Weighted load balancing is similar to least connections, except that servers with a higher weight value receive a larger percentage of connections at a time. The dynamic weight is polled for the specified real server, and that weight determines the percentage of the current connections that are given to the server. The default weight is 0 if it does not receive any SNMP response.

For example, in a configuration with five servers of various weights, the percentage of connections is calculated as follows:






• Total weight of all servers = 24

The result is that Server1 gets 7/24 of the current number of connections, Server2 gets 8/24,

Server3 gets 2/24, and so on. If a new server, Server6, is added with a weight of 10, the new server gets 10/34.


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Overview

If the SNMP-weight indicates that your fastest server gets 50 percent of the connections, the server will get 50 percent of the connections at a given time. However, because the server is faster than others, it can complete more than 50 percent of the total connections overall by servicing the connections at a higher rate. As a result, the weight is not a fixed ratio but instead adjusts to server capacity over time.

Dynamic-weighted Reverse

The SNMP response from each server is regarded as a performance weight. Reverse-Weighted load balancing is similar to Direct-Weighted, except that the SNMP-weight will be calculated by the difference of the maximum based value and the dynamic SNMP response value (max. based value

– SNMP response). The server load balance will balance the same way as the direct-weighted predictor with the dynamically calculated SNMP-weight value.

For an example of CPU usage, if you configure the maximum based value to 100% and the SNMP response is 90% of CPU usage, the SNMP weight becomes 10% (100 - 90 = 10). The server load balance does direct-weight load balancing with the 10% unused CPU time. In other words, servers with a higher SNMP response (a higher CPU usage and lower SNMP-weight) receive a lower percentage of connections at a time.

Server response time

Distributes traffic among real servers based on a dynamic weight value that is derived from the response time of health check packets. If Layer 7 health check is enabled, application response time is used. If Layer 4 health check in enabled, response time based on TCP SYN and TCP SYN

ACK packets is used. The response time weight is derived from the actual time response measurement where the shorter the response time, the larger the response time weight value computed. The response time wait is calculated according to the following rules:

• If the response time is 0, the weight is 1000

• If the response time is greater than 100 ms, the weight is 1

• If the response time is between 0.1 and 100 ms, the weight is 100 divided by the response time (in 0.1 ms intervals)

The response time predictor is only applicable to TCP traffic.

The server response time predictors can be applied globally to apply for the entire Brocade Virtual



Sticky connections

When a service request by a client mandates a series of sequential TCP or UDP port connections to be served by the same real server, you can enable a sticky connection on that TCP or UDP virtual server port. For example, if a user is accessing dynamically generated pages, the client must consistently attach to the same server; otherwise, the state information is lost. By default, the sticky parameter is disabled for virtual service ports.


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Application port groups

Application groups enhance the sticky connections method by allowing you to group up to four TCP or UDP ports with another, “primary” TCP or UDP port. When the Brocade Virtual ADX sends a client request for the primary port to a real server, requests from the same client for a port that is grouped with the primary port also go to the same real server. The application group method, like the sticky method, is governed by the sticky age.

The Brocade Virtual ADX automatically sends requests for the grouped ports to the same real server as the “primary” port, as long as the sticky timer has not expired. You must define all the ports in an application group individually in the VIP, and you must configure all of them to be sticky.

Concurrent connections

The concurrent connection option is similar to the sticky option. However, instead of supporting sequential connections to the same server, the concurrent connection option supports both a primary connection and secondary connections. The connections are supported at the same time.

The primary connection is the controlling connection and dictates the resource, such as a server, to which subsequent or secondary connections are made.

When the controlling connection is established, the server dynamically assigns a TCP or UDP port to which the client should open subsequent or secondary connections. Subsequent connections from that client are accepted on the server as long as the controlling connection is still active.

Figure 2 shows an example of a concurrent connection. A client initiates a session request to an

application supported on servers S1, S2, and S3. When the SLB switch receives the request, the switch forwards the request to server S2. This forms the primary connection. Then S2 dynamically assigns a port, 10000, to the application and forwards it to the client.

FIGURE 2 Concurrent connections in operation on an SLB network

NOTE

The method the server uses to communicate the dynamic port to the client is application-specific.


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Overview

The Brocade Virtual ADX switches all subsequent connections to S2 to ensure that the application session completes successfully.

By default, the concurrent property of a virtual TCP or UDP service port is enabled except for FTP,

Telnet, TFTP, HTTP, and SSL ports.

Remote Servers

The application servers that are a Layer 3 hop away (in other words, in a different subnet that is separated by router) are identified as remote servers in the Brocade Virtual ADX.

Direct Server Return

DSR (Direct Server Return) configures the Brocade Virtual ADX to instruct real servers to send client responses directly to the clients instead of sending the responses back through the Brocade

Virtual ADX. As a result, the clients experience faster response times and the Brocade Virtual ADX is free to support more sessions to serve more clients.

The Brocade Virtual ADX supports both Layer 2 Direct Server Return (L2 DSR) and Layer 3 Direct

Server Return (L3 DSR).

• In an L2 DSR configuration, the Brocade Virtual ADX and the real servers are on the same subnet.

• In an L3 DSR configuration, the Brocade Virtual ADX and the real servers need not be on the same subnet; they can be connected through a router.

Understanding L2 DSR

As in standard SLB configurations, an L2 DSR-configured Brocade Virtual ADX sends client requests addressed to a VIP to a load balanced real server. However, the Brocade Virtual ADX does not translate the destination IP address in the client’s request from the VIP into the real server’s IP address as in other SLB configurations. Instead, the Brocade Virtual ADX leaves the destination IP address unchanged. And the Brocade Virtual ADX also formats the client request packets in such a way that the real servers respond directly to the clients, instead of sending the responses back through the Brocade Virtual ADX.

For L2 DSR to work you must configure a loopback interface on each real server and give the loopback interface the same IP address as the VIP. Because the Brocade Virtual ADX sends the client traffic to the real server without translating the destination address from the VIP into the real server's IP address, the real server receives the client traffic addressed to its loopback address and responds directly to the client.


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Figure 3 shows an example of a Brocade Virtual ADX deployed in an L2 DSR configuration.

FIGURE 3 Brocade Virtual ADX in an L2 DSR configuration

The example above shows the flow of packets in which the Brocade Virtual ADX and the real servers are Layer 2 connected.

1. The client sends a packet to an VIP on the Brocade Virtual ADX.

2. The Brocade Virtual ADX forwards the packets to the loopback address on the real server.

3. The real server then sends the packet directly to the client.

L2 DSR can be configured on an individual TCP or UDP port basis when you configure your virtual

servers. For a complete discussion of L2 DSR and a configuration example, refer to “Configuring L2

Direct Server Return” on page 58.

Understanding L3 DSR

As with L2 DSR, a Brocade Virtual ADX configured for L3 DSR enables application servers to respond directly to the clients resulting in faster server-to-client response times and increased connection capacity for the Brocade Virtual ADX.

But unlike L2 DSR, which requires that the Brocade Virtual ADX servers and clients be directly

(Layer 2) connected, in an L3 DSR configuration the servers and clients can be connected using a router.

For L3 DSR to work, the Brocade Virtual ADX must be able to inspect the DSCP field of incoming packets and modify it to a configured value. Also, the real server must be configured to use the VIP address as the source IP address in the response if the received packet has a matching DSCP field value.

A typical configuration includes servers that are one hop away where the Brocade Virtual ADX has additional intelligence to handle health checks response packets.

Figure 4

shows an example of a

Brocade Virtual ADX deployed in an L3 DSR configuration.

FIGURE 4 Brocade Virtual ADX in an L3 DSR configuration


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Configuring basic SLB

In the example, the Brocade Virtual ADX inspects and modifies packets sent to a VIP. The real server uses the L3 DSR VIP as the source address in response packets if the DSCP bit value of the received packet matches the configured value.

1. The client sends a packet to an L3 DSR VIP on the Brocade Virtual ADX.

2. The Brocade Virtual ADX modifies the DSCP field in the packet to a configured value and sends the packet to a real server.

3. The real server examines the DSCP field and (if the field matches the configured value) uses the DSR VIP as a source IP address instead of its own interface IP address. The real server then sends the packet directly to the client.

For a complete discussion of L3 DSR and a configuration example, refer to

“Configuring L3 Direct

Server Return” on page 63.


To configure basic SLB, perform the following tasks:

•

Define the application servers as real servers on the Brocade Virtual ADX. Refer to “Defining the real servers and real application ports” on page 19.

• Define a virtual server. Refer to

“Defining a virtual server (VIP)” on page 20.

• Bind the real servers to the VIP. Refer to

“Binding virtual and real servers” on page 21.

Figure 5 shows an example of a basic SLB configuration. This example uses multiple Web servers

to handle remote Web requests received on the Web site. The Web site URL is assigned to the switch as the focal point for all inquiries as a virtual server address. The virtual server will then forward requests to each of the four Web servers as specified by the predictor (load balancing metric).

The sections following this example show how to configure the Brocade Virtual ADX in the example using the CLI.

FIGURE 5 Basic SLB configuration


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TABLE 6

Domain name

Real and virtual server assignments

Virtual IP Port www.example7.com

10.95.55.1

80

Real IP

10.95.55.21 (Web1)

10.95.55.22 (Web2)

10.95.55.23 (Web3)

10.95.55.24 (Web4)

Port

80

80

80

80

Configuration guidelines

The following configuration guidelines should be observed when configuring SLB on a switch:

• Each virtual server name and IP address must be unique.

• Each virtual server can have multiple TCP or UDP ports assigned.

• Each real server name and IP address must be unique.

• Each real server can have multiple TCP or UDP ports assigned.

• Each real server TCP or UDP port can be bound to one or more virtual TCP or UDP ports.

NOTE

If you need to map a real server port to multiple VIP ports, you can use the multiple port binding feature. Refer to

“Multiple port binding” on page 69.

• One virtual TCP or UDP port can be bound to one or more real TCP or UDP ports.

NOTE

If you need to map virtual port to multiple real server ports, you can use the many-to-one TCP or UDP port binding feature. Refer to


• The default load-balancing predictor is Round Robin.

• Binding must be done to establish a relationship between virtual and real servers.

Defining the real servers and real application ports

Identify your application servers as real servers. Define a real server using its name and IP address. Add your application ports under these real servers.

NOTE

When you add a port other than port 80 to a real server, the port number l4-check-only command is automatically applied to the configuration. You cannot remove this command from the non-HTTP ports.

Virtual ADX(config)#server real Web1 10.95.55.21

Virtual ADX(config-rs-Web1)#port http

Virtual ADX(config-rs-Web1)#port dns

Virtual ADX(config-rs-Web1)#exit





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Syntax: [no] server real [ name ] ip-address

Syntax: [no] port tcp/udp-port

The server name can be any alphanumeric string of up to 42 characters.

After you have defined the real server, you can refer to it using its name or IP address, and modify its configuration.

Virtual ADX(config)#server real Web1

Virtual ADX(config-rs-Web1)#port ftp


Virtual ADX(config)#server real 10.95.55.21

Virtual ADX(config-rs-Web1)#port ftp


Virtual ADX(config)#no server real Web1

NOTE

If a real server is not reachable from the Brocade Virtual ADX at Layer 2 (does not respond to ARP requests from the Brocade Virtual ADX), then define it as a remote server.

NOTE

Optionally, if you have a one-armed topology, you may need to enable source NAT along with source-ip to ensure that return traffic flows through the Brocade Virtual ADX.

Defining a virtual server (VIP)

After you define the actual Web server’s physical addresses (real server), you then need to configure the external Web server address on the switch. The external Web server is the virtual server.

It is the IP address or server name to which client browsers send requests. Add the TCP or UDP application ports the Brocade Virtual ADX will load balance. These should be the same application ports you specified for the real servers.

To define the virtual name and address that is the access point for the company's Web site and the supported service, enter commands such as the following.

Virtual ADX(config-rs-Web4)#server virtual-name-or-ip www.altergo.com 10.95.55.1

Virtual ADX(config-vs-www.altergo.com)#port http

Syntax: [no] server virtual-name-or-ip [ name ] ip-address



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After you have defined the virtual server, you can add configuration statements or delete the server by referring to the server’s IP address or name, by entering commands such as the following.

Virtual ADX(config)#server virtual-name-or-ip www.altergo.com 10.95.55.1

Virtual ADX(config-vs-www.altergo.com)#port http

Virtual ADX(config-vs-www.altergo.com)#exit

Virtual ADX(config)#server virtual-name-or-ip 10.95.55.1


Virtual ADX(config)#server virtual-name-or-ip www.altergo.com


Virtual ADX(config)#no server virtual-name-or-ip 10.95.55.1

Binding virtual and real servers

After you define the real servers, virtual servers, and TCP or UDP ports, you need to bind the real and virtual servers together. The bindings are based on the TCP and UDP application ports you are load balancing.

To bind the four Web servers shown in

Figure 5 to the virtual server address, enter the following

commands.

Virtual ADX(config-rs-Web4)#server virtual-name-or-ip www.altergo.com

Virtual ADX(config-vs-www.altergo.com)#bind http Web1 http




Syntax: [no] bind tcp/udp-port-number real-server-name tcp/udp-port-number

NOTE

For clarity, the bindings in the example are shown as four separate entries. You can enter all the binding information as one command: bind http Web1 http Web2 http Web3 http Web4 http


The Load-Balancing Predictor Method can be configured either globally or per-virtual server as described in the following.

To globally change the load-balancing method used by the Brocade Virtual ADX, enter the following command.

Virtual ADX(config)#server predictor round-robin

To change the load-balancing method used by the Brocade Virtual ADX for virtual server “v1”, enter the following commands.

Virtual ADX(config)#server virtual-name-or-ip v1

Virtual ADX(config-vs-v1)#predictor enhanced-weighted

Syntax: [no] server predictor { least-conn | round-robin | weighted-round-robin | weighted-round-robin-static |weighted | enhanced-weighted | dynamic-weighted { direct | reverse } | response-time }

Selecting the least-conn parameter configures the Least Connections load-balancing method. This method is described in

“Least connections predictor” on page 8.


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Selecting the round-robin parameter configures the Round Robin load-balancing method. This method is described in

“Round Robin predictor” on page 8.

Selecting the weighted-round-robin parameter configures the Weighted Round Robin

load-balancing method. This method is described in “Weighted Round Robin predictor” on page 9.

Selecting the weighted-round-robin-static parameter configures the Static Weighted Round Robin

load-balancing method. This method is described in “Static Weighted Round Robin predictor” on page 9.

Selecting the weighted parameter configures the Weighted load-balancing method. This method is

described in “Weighted and Enhanced Weighted load balancing” on page 10.

Selecting the enhanced-weighted parameter configures the Weighted load-balancing method. This method is described in

“Weighted and Enhanced Weighted load balancing” on page 10.

Selecting the response-time parameter configures the response time load-balancing method. This method is described in

“Server response time” on page 14. Configuring the response time load

balancing method requires that you configure a smooth factor as described in “Configuring the smooth factor” on page 25.

Selecting the dynamic-weighted parameter configures the Dynamic Weighted load-balancing method. This method can be configured as either direct or reverse as described in

“Dynamic weighted predictor” on page 13. Details about configuring the Dynamic Weighted load-balancing

method as direct or reverse are described in

“Configuring dynamic weighted predictor” on page 24.

If you enable any of the weighted methods, you must configure the weights for all real servers involved. The weights can range from 0 through 65000. This configuration is described in

“Configuring a weighted predictor” on page 22.

NOTE

If a given VIP port is bound to multiple ports on the same real server, then the least-connection predictor may not produce even traffic distribution. Use the round-robin predictor instead.

For overview information, refer to

“Load-balancing predictor” on page 8.

Configuring a weighted predictor

Several of the Load-Balancing Predictor Methods used on the Brocade Virtual ADX require that weights be assigned to the real servers. The Brocade Virtual ADX uses a formula based on each real server’s assigned weight to calculate the server load for the real servers, then selects the real server as determined by the predictor that is configured on the Brocade Virtual ADX.

To configure a Load-Balancing Predictor Method, perform the following tasks.

1. Assign weights to the real servers.

2. Configure the weighted predictor either globally or for a virtual server.

NOTE

If a real server port is bound under a VIP but a weight is not configured under the real server, the

Brocade Virtual ADX will assume the weight for that real server is 1.


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Assigning weights to the real servers

When configuring Weights on a real server, consider the following:

• Real Server Weight assignments apply to all ports configured under the real server.

• For the Weighted Round Robin predictor, server weights are assigned at the server level and not at the server port level. The load balancing, however, is based on per-server port.

• The Weighted Round Robin predictor has VIP port-level granularity. This granularity is reflected in the output from the show server session and show server conn commands, because they display output for the Weighted Round Robin predictor at a per vip-port level.

To configure weights for three real servers, enter commands such as the following.

Virtual ADX(config)#server real rsA

Virtual ADX(config-rs-rsA)#weight 1

Virtual ADX(config-rs-rsA)#exit

Virtual ADX(config)#server real rsB

Virtual ADX(config-rs-rsB)#weight 2

Virtual ADX(config-rs-rsB)#exit

Virtual ADX(config)#server real rsC

Virtual ADX(config-rs-rsC)#weight 3

Virtual ADX(config-rs-rsC)#exit

Syntax: [no] weight weight-value

The weight command assigns a performance weight to each server or firewall. Servers or firewalls with a larger or higher weight assigned receive a larger percentage of connections.

The weight-value variable specifies the real server’s weight relative to other real servers in terms of the number of connections on the server. More precisely, this weight is based on the number of session table entries the Brocade Virtual ADX has for TCP or UDP sessions with the real server. You can specify a value from 0 through 65000. The default is 1.

Configuring the weight for real servers

This weight command specifies the weight assigned to the real server. It is used for the weighted and least connection with server response-time-weights for load balancing methods.

Suppose you want to assign a higher weight to real server Web1 to bias traffic toward that server.

No other changes are made to the weights of Web servers 2, 3, and 4, and they remain configured

with the default weight of zero ( Figure 5 ). Enter commands such as the following.

Virtual ADX(config)#server virtual-name-or-ip www.example7.com

Virtual ADX(config-vs-www.example7.com)#predictor weighted

Virtual ADX(config-vs-www.example7.com)#server real Web1 10.95.55.21

Virtual ADX(config-vs-www.example7.com)#exit

Virtual ADX(config)#server real Web1

Virtual ADX(config-rs-Web1)#weight 10

Syntax: weight least-connections-weight

The least-connections-weight variable specifies the real server’s weight relative to other real servers in terms of the number of connections on the server. More precisely, this weight is based on the number of session table entries the Brocade Virtual ADX has for TCP or UDP sessions with the real server. You can specify a value from 0 to 65000. The default is 1. However, if you want to use a weight value only for the Server Response Time but not for the number of connections, specify 0 for this variable.


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If you enter a value for response-time-weight , the Brocade Virtual ADX adds the two weight values together when selecting a real server. If you specify equal values for each parameter, the Brocade

Virtual ADX treats the weights equally. The number of connections on the server is just as relevant as the server’s response time. However, if you set one parameter to a higher value than the other, the Brocade Virtual ADX places more emphasis (weight) on the parameter with the higher value.

For example, if you specify a higher server response time weight than the weight for the number of connections, the Brocade Virtual ADX pays more attention to the server’s response time than to the number of connections it currently has when considering the real server for a new connection.

Configuring dynamic weighted predictor

This section contains the following sections:

•

“Configuring a real server with SNMP query requirements” on page 24

•

“Configuring a virtual server with a dynamic weighted predictor” on page 24

Configuring a real server with SNMP query requirements

A list of the SNMP Object ID (OID) can be configured under a real server. An OID represents the weight of the real server, for example server CPU utilization or its memory usage.

To configure SNMP query requirements use the following command.

Virtual ADX(config-rs-rs1)#snmp-request oid 1 1.3.6.1.2.1.25.3.3.1.2.1

Syntax: snmp-request oid ID string

The ID variable specifies the snmp-request entry identification, decimal value 1 - 256

The string variable specifies the ASCII string ASN.1 format - 1.3.6.1.2.1.25.3.3.1.2.1

SNMP versions 1 and 2 use community strings to restrict SNMP access. The administrator must configure an SNMP community string to match with those configured in all the real servers.

Virtual ADX(config-rs-rs1)#snmp-request community public

Syntax: snmp-request community string [ port number ]

The string variable is the SNMP community string. Enter a string with a maximum of 32 characters.

The port port option specifies the snmp-request host UDP port (Default: port 161).

You can configure the frequency of the periodic SNMP queries using the following command.

Virtual ADX(config)#server snmp-poll 5

Syntax: server snmp-poll num

The num variable specifies the decimal value in seconds (Default: 3 sec.)

Configuring a virtual server with a dynamic weighted predictor

Select a dynamic-weighted direct or reverse predictor and an SNMP OID.


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Dynamic-weighted direct

To configure a dynamic-weighted reverse predictor, use the following command.

Virtual ADX(config-vs-vs1)#predictor dynamic-weighted direct oid 1

Syntax: predictor dynamic-weighted direct oid ID

Configuration example

server virtual-name-or-ip vs1 10.1.1.151

predictor dynamic-weighted direct oid 1

port http

bind http rs1 http rs2 http rs3 http

Dynamic-weighted reverse

To configure a dynamic-weighted reverse predictor, use the following command.

Virtual ADX(config-vs-vs1)#predictor dynamic-weighted reverse oid 1 max 50

Syntax: predictor dynamic-weighted reverse oid ID [max value ]

NOTE

The max value option subtracted from the reverse weight is equal to the direct weight.


Virtual ADX(config)#server snmp-poll 5

Virtual ADX(config)#server real rs1 10.1.1.1

snmp-request community public port 161

snmp-request oid 1 1.3.6.1.2.1.25.3.3.1.2.1

snmp-request oid 2 1.3.6.1.2.1.1.3.0

port http

port http keepalive

Virtual ADX(config)#server virtual vs1 10.200.1.1

predictor dynamic-weighted direct oid 1

Configuring the smooth factor

This section applies to the server response time load balancing method.

The Brocade Virtual ADX calculates the server response time value for a real server by regularly collecting response time samples, then using a calculation to smooth the values of the samples and derive a single response time value for the real server. The Brocade Virtual ADX relies on the health-check traffic to sample the response time. As the default interval of health checks to real servers is five seconds, the Brocade Virtual ADX collects the response time samples for every five seconds. The sampling rate can vary slightly depending on the processing the Brocade Virtual ADX is performing.


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To smooth the samples out, the Brocade Virtual ADX uses the following calculation:

R = ((S * previous_R) + ((100 - S) * new_R)) / 100 where:

R = Response time

S = smooth factor, which is configurable and can be from 1to 99. The default is 60. A large value gives the previous response time more weight than the new response time. A small value gives the new response time more weight than the previous response time.

For example, if a given real server’s previous response time value was two milliseconds, and a new measurement also results in two milliseconds, the calculated server response time using the smooth factor of 90 is as follows:

R = ((90 * 2) + ((100 - 90) * 2) / 100

R = 180 + 20 / 100

R = 200 / 100

R = 2

If the real server’s response time slows due to processing for additional connections, the slower response time affects the Server Response Time calculation for the server. For example, if the next server response time sample is five milliseconds instead of two, the Server Response Time calculation is as follows:

R = ((90 * 2) + ((100 - 90) * 5) / 100

R = 180 + 50 / 100

R = 230 / 100

R = 2.3

Since the real server’s response time has slowed by two and a half times, the server’s response time calculation biases the Brocade Virtual ADX away from selecting that server for new connections.

You can affect the degree of difference in subsequent response time weights by changing the smooth factor (S). For example, if you change the smooth factor from 90 to 50, the calculations shown above have the following results:

Here is the calculation when the previous and new response times are 2 milliseconds:

R = ((50 * 2) + ((100 - 50) * 2) / 100

R = 100 + 100 / 100

R = 200 / 100

R = 2

Here is the calculation if the server’s next response time is 5 milliseconds.

R = ((50 * 2) + ((100 - 50) * 5) / 100

R = 100 + 250 / 100

R = 350 / 100

R = 3.5


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Notice that the differences between the first and second samples are much greater when the smooth factor is 50 than when the smooth factor is 90. A large value gives the previous response time more weight than the new response time. A small value gives the new response time more weight than the previous response time.

You can change the smooth factor on an individual virtual server’s application port basis.

If you change the smooth factor for a virtual server, the change affects all Server Response Time calculations for the real servers bound to the virtual server.

If you change the smooth factor for an application port, the change affects Server Response Time calculations only for port bindings that use that application port.

To change the smooth factor for a virtual server’s application port, enter a command such as the following at the configuration level for the virtual server:

Virtual ADX(config-vs-Joes_Garage)#port 80 smooth-factor 50

Syntax: [no] smooth-factor num

The num variable specifies the smooth factor value the server response time calculation uses. You can specify a number from 1 to 99. The default is 60.

Real server ports

You can globally configure an application port by configuring its port profile. When you configure a port profile, the parameters in the profile apply to all servers that include the application port. To configure a port profile, refer to

“Port profiles and attributes” on page 187.

You also can locally define some SLB port parameters on an individual real-server basis:

• State (enabled or disabled) – Ports are enabled by default.

• Keepalive health check state – Keepalive health checks are enabled if you have configured a port profile for the port and did not globally disable the health check. You can disable the keepalive health check locally for the port on a specific real server while leaving the health check globally enabled.

• Layer 7 health check parameters – For some application ports that are known to the Brocade

Virtual ADX, you can customize the Layer 7 health checks for individual real servers.

Disabling or re-enabling application ports

Application ports are enabled by default. To disable an application port on a real server, use either of the following methods.

To disable an application port, enter commands such as the following.

Virtual ADX(config)#server real Sy_Borg 192.168.4.69

Virtual ADX(config-rs-Sy_Borg)#port http disable

Syntax: [no] port tcp/udp-port disable | enable

To re-enable a port, enter commands such as the following.

Virtual ADX(config)#server real Sy_Borg 192.168.4.69

Virtual ADX(config-rs-Sy_Borg)#no port http disable


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Real server ports

To disable all the application ports on a real server, enter the following command at the configuration level for the server.

Virtual ADX(config-rs-R1)#port disable-all

To re-enable all the application ports, enter the following command.

Virtual ADX(config-rs-R1)#no port disable-all

Syntax: [no] port disable-all

Globally disabling application ports

You can globally disable a Layer 4 port on the Brocade Virtual ADX. The port can be disabled for all real servers, all virtual servers, or all real and virtual servers. After you disable a port globally, you can enable the port on individual real or virtual servers as necessary. By default, all real and virtual ports are enabled.

When the Brocade Virtual ADX is booted, if the command to globally disable a real or virtual port exists in the startup-config file, the specified port is disabled at startup. When a real or virtual port is created, and the port has been disabled globally, the real or virtual port is disabled as well. You must enable the port explicitly.

To disable all real HTTP ports, enter the following commands.

Virtual ADX(config)#server port 80

Virtual ADX(config-port-http)#disable real

Virtual ADX(config-port-http)#

To disable all virtual HTTP ports, enter the following commands .


Virtual ADX(config-port-http)#disable virtual


To disable all real and virtual HTTP ports, enter the following commands .


Virtual ADX(config-port-http)#disable


Syntax: disable [real | virtual]

Disabling SLB to a server when an application goes down

By default, if an application on a real server becomes unavailable, but the real server itself is still up, the Brocade Virtual ADX continues to include the real server in its load balancing decisions for the application. For example, if the HTTP application on a real server stops responding to Layer 4 health checks, but the real server continues to respond to Layer 3 health checks (IP pings) from the

Brocade Virtual ADX, the Brocade Virtual ADX continues to forward HTTP requests to the real server.

NOTE

New connections are only sent to servers that have passed an application health check.

In some configurations, such as those that use a cluster of servers for an application, you may want to configure the Brocade Virtual ADX to stop sending requests to a server when the requested application is down on the server. For example, this feature is useful in an NFS configuration.


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When you enable this feature, the Brocade Virtual ADX resets the connection for an unavailable

TCP or UDP application on a real server in addition to redirecting future requests away from this real server.

To enable the feature, enter commands such as the following:

Virtual ADX(config)#server virtual vip-test 10.50.1.250

Virtual ADX(config-vs-vip-test)#port http

Virtual ADX(config-vs-vip-test)#port http reset-on-port-fail

Virtual ADX(config-vs-vip-test)#

The above example enables the feature for the http application defined under the virtual server.

Similarly, this feature can be enabled for the other application ports as well.

Syntax: [no] port application-port reset-on-port-fail

Slow-start mechanism

When the Brocade Virtual ADX begins sending client requests to a real server that has recently gone online, it allows the server to ramp up by using the slow-start mechanism. The slow-start mechanism allows a server (or a port on the server) to handle a limited number of connections at first and then gradually handle an increasing number of connections until the maximum is reached.

The Brocade Virtual ADX uses two kinds of slow-start mechanisms:

• The non-configurable server slow-start mechanism applies to a real server that has just gone online.

• The configurable port slow-start mechanism applies to individual TCP application ports that have just been activated on a real server.

Refer to “Slow-start mechanism” on page 225 for more information.

Enabling or disabling the keepalive health check

When you configure a port profile for an application port, the L4/L7 keepalive health check for that port is enabled automatically. You also can enable or disable the keepalive health check for an application port on a specific real server, without affecting the global setting for the health check.

NOTE

If you configured a port profile for the port, the keepalive health check is enabled.

To enable the keepalive health check, enter commands such as the following.

Virtual ADX(config)#server real Auto_Plooker 192.168.2.69

Virtual ADX(config-rs-Auto_Plooker)#port http keepalive

To disable the keepalive health check, enter commands such as the following.

Virtual ADX(config)#server real Auto_Plooker 192.168.2.69

Virtual ADX(config-rs-Auto_Plooker)#no port http keepalive

Syntax: [no] port tcp/udp-port keepalive


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Real server ports

Configuring a real port as TCP-only or UDP-only

This feature allows you to configure a Brocade Virtual ADX to allow traffic to a virtual port being load-balanced to a different set of real ports based on its protocol (TCP or UDP). No configuration change is required for the virtual server. A virtual port can be bound to tcp-only, udp-only and a regular real port at the same time.

By default, a real port accepts both TCP and UDP traffic. If a real port is configured as tcp-only, when a given traffic is UDP traffic, the real port will not participate in the server selection, even if it is bound to the virtual port. Similarly, a udp-only port will not be considered for TCP traffic.

The behaviors of all predictors remain unchanged among eligible real ports (i.e., tcp-only and regular real ports for TCP traffic, and udp-only and regular real ports for UDP traffic).

The tcp-only, and udp-only commands for a real port are configured under the real port configuration mode as shown in the following.

Virtual ADX(config)#server real R1 10.10.10.1

Virtual ADX(config-rs-R1)#port 80 tcp-only

Virtual ADX(config-rs-R1)#exit


Virtual ADX(config-rs-R2)#port 80 udp-only

Syntax: [no] port portnum {tcp-only | udp-only}

The portnum variable specifies the application port you want to make tcp-only or udp-only.

TCP only and UDP only are mutually exclusive. This means that when tcp-only is configured, udp-only cannot be configured for a port at the same time. udp-only will be automatically disabled if tcp-only is configured, and vice versa.

Configuring a stateless port

By default, the Brocade Virtual ADX creates session table entries for sessions between clients and applications on real servers. The Brocade Virtual ADX uses the session table entries to maintain state information for the sessions. The Brocade Virtual ADX uses the state information for features such as health checking and session failover in Hot Standby HA configurations.

You can configure individual application ports to be stateless. The Brocade Virtual ADX does not maintain state information for a stateless port. Making a port stateless is useful when you want to conserve session table resources or when you have configured the VIP to be transparent.

For examples and configuration information, refer to

Chapter 3, “Stateless Server Load Balancing”

.

To configure an application port to be stateless, enable the stateless parameter on the port in the virtual server, such as the following.


Virtual ADX(config-rs-R1)#port http





Virtual ADX(config)#server virtual-name-or-ip StatelessHTTP 192.168.4.69

Virtual ADX(config-vs-StatelessHTTP)#port http stateless

Virtual ADX(config-vs-StatelessHTTP)#bind http R1 http


Syntax: [no] port tcp/udp-portnum stateless


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The tcp/udp-portnum variable specifies the application port you want to make stateless.

NOTE

The Brocade Virtual ADX supports port translation for stateless SLB. Port translation is useful when clients connect to real servers directly. Without port translation, if a client connects to a real server directly, the Brocade Virtual ADX automatically replaces the source IP address to a VIP. When you configure port translation, the Brocade Virtual ADX overcomes the limitation of performing NAT on all packets initiated from the real server. NAT does not occur because the Brocade Virtual ADX does not match the port number.

NOTE

The Brocade Virtual ADX supports stateless SLB for any TCP and UDP application protocols. For a

TCP application, hashing must be enabled on the Brocade Virtual ADX. For a UDP application, you can enable or disable hashing on the Brocade Virtual ADX.

Source NAT

Source NAT configuration is useful where a Brocade Virtual ADX is connected in one-armed mode; for example where it is connected to the network infrastructure through an uplink as shown in

Figure 6 .

In this situation the Brocade Virtual ADX passes the source IP address of the client to a back-end application server. If these servers have a direct path to the client, (as would be the case in one-armed design) the response will bypass the Brocade Virtual ADX in the return path. This bypass breaks the traffic flow because the client sees the response coming from the IP address of the real server, instead of the IP address of the virtual server.

With Source NAT configured, a Brocade Virtual ADX replaces the IP address of a client IP with the IP address of the Brocade Virtual ADX in request packets forwarded to the real server. This action forces the real server to forward replies to the Brocade Virtual ADX instead of bypassing it.

Figure 6 provides an example of what can occur when a real server has a path back to a client that

bypasses a Brocade Virtual ADX without Source NAT enabled as described in the following.

1. A request from the Client arrives at the Brocade Virtual ADX through a Layer 2 switch.

2. The Brocade Virtual ADX translates the VIP IP address to the IP address of the real server and forwards the request to the real server through the Layer 2 switch.

3. The real server sees the request coming from the IP address of the client and replies back directly through the Layer-2 switch bypassing the Brocade Virtual ADX.


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Source NAT

4. The Client sees the response coming from an unknown IP address (other than the one that it sent the request to) and drops the packet.

FIGURE 6 Scenario without source NAT configured

In

Figure 7

the traffic flow of the configuration is changed by enabling Source NAT as described in the following:

1. A request from the Client arrives at the Brocade Virtual ADX through a Layer 2 switch.

2. The Brocade Virtual ADX translates the VIP IP address to the IP address of the real server, replaces the IP address of the client with it’s own IP address and forwards the request to the real server.

3. The real server sees the request coming from the IP address of the Brocade Virtual ADX and replies back through the Layer 2 switch to the Brocade Virtual ADX.

4. The Brocade Virtual ADX translates the IP address of the real server to the VIP IP address and replies to the client.

FIGURE 7 Scenario with source NAT configured

32

Source NAT can be configured either globally or per real server as described in the following

sections: “Enabling source NAT globally” and “Enabling source NAT on a real server”

.


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Enabling source NAT globally

Source NAT allows the Brocade Virtual ADX to use a specific source IP address as the source for sending packets to real servers, which is useful for operating in a multinetted environment. You can enable source NAT globally or locally on individual real servers. If you enable source NAT globally, the feature applies to all real servers. If you enable the feature locally, the Brocade Virtual ADX performs source NAT only for those real servers. Other locally-attached real servers, on which source NAT is not enabled, must be in the same subnet as the Brocade Virtual ADX.

To enable source NAT globally, enter the following command.

Virtual ADX(config)#server source-nat

Syntax: [no] server source-nat

NOTE

In a system with a large number of barrel processors (BP), the usable source NAT ports are limited.

The larger the number of BPs that a system has, the lesser number of Source ports available for the

BP. It is suggested that you use the “Enabling Port Allocation” feature when all 64 Source IPs are used up. Refer to

“Enabling port allocation per real server for source NAT IP” on page 35 and

“Enabling port allocation per real server for source NAT IP” on page 35 for details.

If you are configuring a pair of Brocade Virtual ADX devices for hot-standby (active-standby) HA and you want to use the same source IP address on each Brocade Virtual ADX, use the server source-nat-ip command instead.

NOTE

If there are sessions that are currently using the source-nat-ip address and you delete that IP address, then you should wait till all the sessions are deleted before using the server source-nat-ip command with the deleted address or before a reload of the Brocade Virtual ADX.

Enabling source NAT on a real server

Source NAT allows the Brocade Virtual ADX to use a source IP address as the source for packets sent to the real server. Source NAT allows the Brocade Virtual ADX to be in more than one subnet. If the real server and the Brocade Virtual ADX are in different subnets and not connected by a router that is multinetted, enable source NAT on the real server.

If you enable source NAT on a real server, the feature applies only to the server. You also can enable source NAT globally. Refer to

“Enabling source NAT globally” on page 33.

To enable source NAT on a real server, enter commands such as the following.

Virtual ADX(config)#server real-name berto

Virtual ADX(config-rs-berto)#source-nat

Syntax: [no] source-nat

Source NAT is disabled by default.


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Source NAT

Configuring a shared source IP address for NAT

Use the server source-nat-ip command to divide the ports used for source NAT for a source IP address.

In a hot-standby (active-standby) HA configuration, this command configures a shared source IP address for NAT. Enter the same command with the same source IP address on each of the

Brocade Virtual ADX devices. The address is active only on one Brocade Virtual ADX (the Brocade

Virtual ADX that is currently active) at a time.

NOTE

This command applies only to hot-standby (active-standby) HA configurations. If you are configuring a shared IP address for use by the real servers as their default gateway, use the standby-ip address under the ve interface or ethernet interface, if the IP assignment is done under ethernet interface.

The gateway parameter is required.

To configure a shared source IP address, enter the command such as the following.

Virtual ADX(config)#server source-nat-ip 10.10.10.5/24 0.0.0.0 port-range 2

Syntax: [no] server source-nat-ip ip-addr ip-mask | prefix default-gateway port-range 1 | 2

The ip-addr ip-mask variable is the source address and subnet mask or prefix. For an IPv6 source address, the prefix length must be equal to or greater than 32.

The default-gateway variable is required. If you do not want to specify a gateway, enter "0.0.0.0".

The port-range parameter specifies which port range this peer uses for source NAT for this source

IP address.Specify 1 for the lower port range or 2 for the upper port range.

Displaying Information about the Shared Source IP Address

To display information about the source IP address, enter the command such as the following.

Syntax: show server source-nat-ip ip-addr

Client subnet based source NAT

The selection of source NAT IP addresses is based on configured client subnets. You can associate a client subnet with a particular source NAT, which is defined on the Brocade Virtual ADX. You can also associate multiple client subnets with the same source NAT IP address, and the same client subnet to multiple source NAT IP addresses. (These association type allow the clients to be load-balanced to real servers belonging to different subnets, and the source NAT IP address selected should belong to the same subnet as the real server).

When a client belonging to a configured subnet makes a new connection request, the source NAT

IP address list corresponding to that client’s subnet is retrieved. Out of this list, a source NAT IP address is selected that is in the same subnet as the selected real server. If the selected source

NAT IP address runs out of source ports, the Brocade Virtual ADX tries to use the next available source NAT IP address for that client’s subnet. The source-nat-ips that have been defined only for that client subnet will be used

To configure this feature, enter the following command.

Virtual ADX(config)#server source-nat 192.168.2.10 10.10.6.1

Syntax: server source-nat client-subnet source-ip

The client-subnet variable is the IP address to which the client belongs .


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The source-ip variable is the source NAT IP address of the subnet with which you want to associate the client subnet. The source NAT IP address you enter must be configured on the Brocade Virtual

ADX.

Enabling port allocation per real server for source NAT IP

For the Brocade Virtual ADX products, the port pools are not shared globally but are allocated to each real server and each real server is able to use the entire pool by itself. To enable port allocation per real server for the source NAPT IP address, use the following command.

Virtual ADX(config)#server source-nat-ip 10.10.10.5 255.255.255.0 0.0.0.0 port-range 2 port-alloc-per-real

Syntax: [no] server source-nat-ip ip-addr ip-mask default-gateway port-range 1|2

[port-alloc-per-real]

This feature is recommended for deployments with large numbers of real servers, which can lead to a shortage of ports and necessitate configuration of additional source NAT IPs.

NOTE

This enhancement only applies to the server source-nat-ip.

NOTE

You need to write memory and reload after you configure this feature.

Consider the following when enabling port allocation per real server:

• When you enable port allocation per real server, you must reload the Brocade Virtual ADX.

Otherwise, the SLB traffic fails.

• The Brocade Virtual ADX does not use the source-nat-ip default-gateway parameter for remote server health checks as well as for forwarding SLB traffic to the remote server.

• You should not enable or disable this functionality while the IP addresses are in use by the traffic flow. You must bring the number of traffic flows utilizing this IP address to zero or remove the command and redefine it.

As an example, for changing from statement #1 to statement #2 below, either bring the traffic level to nil or negate the command first using "no server...." and then re-define it.

statement #1: server ... port-range 1 statement #2: server ... port-range 1 port-alloc-per-real

• The maximum number of configured source-nat-ip addresses that can be supported by the

“port allocation per real server” feature is 16.

You can configure the Brocade Virtual ADX to log a message when source NAT IP runs out of ports.

Syntax: [no] source-ip-log


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Remote server

Remote server

If the server is attached through one or more router hops, configure the server as remote. When you add a remote real server, the Brocade Virtual ADX does not include the server in the predictor

(load-balancing method). Instead, the Brocade Virtual ADX sends traffic to the remote server only if all local real servers are unavailable. The server name is used to bind the server IP address, so that the real server name can be used to represent the server.

To configure a remote real server, enter a command such as the following.

Syntax: server remote-name name ip-addr

The server name can be any alphanumeric string of up to 42 characters.

This command is used in conjunction with the server load balancing feature on the Brocade Virtual

ADX.

Refer to “Unbinding all application ports from virtual servers” on page 119.

Sticky and concurrent connections

Configuring sticky ports

By default, the Brocade Virtual ADX sends a client’s request to the next available real server based on the load balancing method. This is true regardless of whether the client has already sent a request for the same application. If you want the Brocade Virtual ADX to send all of a client’s requests for a given application to the same real server during a client’s session with the server, configure the application port to be sticky.

Both the track port and track port group methods of application port grouping require you configure

the application ports involved as sticky ports. For more information, see “Application port grouping” on page 43.

NOTE

For servers that use passive FTP in a DSR configuration, configure the FTP ports to be both sticky and concurrent.

NOTE

When a default port is configured as “sticky”, Brocade Virtual ADX creates the sticky session in each destination port and not in the whole destination port.

To configure a TCP or UDP port as sticky, use the port sticky command when you add that port to a virtual server:

Virtual ADX(config)#server virtual-name-or-ip v1 10.157.22.1

Virtual ADX(config-vs-v1)#port 80 sticky

In this example, the commands configure HTTP (port 80) as sticky.

Syntax: [no] port tcp/udp-port sticky


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Configuring stickiness based on client’s subnet

The sticky function causes the Brocade Virtual ADX to send all of a client’s requests for a given application to the same real server during the client’s session with the server. By default, the stickiness is based on the client's IP address. You can configure the Brocade Virtual ADX to base the stickiness on the client’s subnet, rather than IP address. All requests originating from a specific subnet for a given application are sent to the same real server.

For example, to send all HTTP requests originating from a given subnet to the same real server, enter commands such as the following.

Virtual ADX(config)#server virtual-name-or-ip vs1 10.10.10.10

Virtual ADX(config-vs-vs1)#port http

Virtual ADX(config-vs-vs1)#port http client-subnet-sticky prefix-length 24

Syntax: [no] port portnum client-subnet-sticky prefix-length prefix-length or

Syntax: [no] port portnum client-subnet-sticky subnet-mask client-subnet-mask

In this example, client requests from subnet 192.168.9.x would go to the same real server. Sub-net sticky connections are aged out according to the sticky age setting, in the same way regular sticky connections are aged out.

The features port sticky and port client-subnet-sticky cannot be configured together on the same port on the same virtual server.

Setting the sticky age

You can age out inactive sticky server connections. A connection is sticky if you configure the

Brocade Virtual ADX to send successive requests from the same client for the same application port to the same real server, instead of load balancing the requests to different real servers.

Sticky connections are defined on a virtual server port of an SLB switch when a service request by a client mandates a series of sequential TCP or UDP port connections to be served by the same real server. For example, if a client is accessing dynamically generated pages, the client must consistently attach to the same server, otherwise the state information will be lost.

The sticky age is a global setting applying to all virtual servers; you can also set the sticky age for an individual virtual server. The sticky age for the individual virtual server overrides the global setting.

To set the sticky age globally, enter a command such as the following.

Virtual ADX(config)#server sticky-age 20

To set the sticky age for an individual virtual server, enter commands such as the following.


Virtual ADX(config-vs-v1)#sticky-age 20

Syntax: [no] server sticky-age minutes

The minutes variable is the sticky age in minutes. Enter an integer from 2 to 60. The default is 5 minutes.


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Allowing sticky ports

You can configure the Brocade Virtual ADX to continue using a sticky port (a persistent connection) even if you have entered a command to unbind the port or the port is disabled.

When you unbind an application port from a server, the Brocade Virtual ADX temporarily places the port in the aw_unbnd (awaiting unbind) state. If you delete an application port, the Brocade Virtual

ADX temporarily places the port in the aw_del (awaiting delete) state. These temporary states allow open sessions on the port to be completed before the port is unbound or removed.

By default, when the Brocade Virtual ADX receives a new request associated with a sticky port in the aw_unbnd state, the Brocade Virtual ADX establishes the session on another real server, not the real server from which you are unbinding the port.

You can configure the Brocade Virtual ADX to accept new sessions for the same real server for a sticky port, even under the following conditions:

• The real server port is in the aw_unbnd state.

• The real server port is in the aw_del state.

• The real server port is disabled.

To do so, enter the following command.

Virtual ADX(config)#server allow-sticky

Syntax: [no] server allow-sticky [refresh-age]

The refresh-age option resets the age of a sticky session on the port whenever a new connection associated with the sticky port is established. This parameter ensures that the session stays up indefinitely until it is no longer needed.

By default, the Brocade Virtual ADX does not reset the age of the session when new connections are established. Instead, the session times out after the sticky age expires.

If you use refresh-age, the Brocade Virtual ADX resets the age of the session to the value of the sticky age. For example, if the sticky age is five minutes (the default), when the Brocade Virtual ADX establishes a new session on the sticky port, the Brocade Virtual ADX resets the age time for the session to five minutes. Each time the Brocade Virtual ADX receives another connection request associated with the sticky session, the Brocade Virtual ADX resets the session age again.

Increasing the sticky-age per VIP longer than 60 minutes

Several applications require sticky age to be longer than the 60 minute global maximum that is

configured using the server sticky-age command as described in “Setting the sticky age” on page 37. This might occur where a client connects in the morning and requires connectivity

throughput the day.

There are also situations where you may want to configure a different value per virtual server. The following command allows you to apply a multiplier value to the global sticky-age value for a specific virtual server.


Virtual ADX(config-vs-vs1)#sticky-age-multiplier 5

Syntax: sticky-age-multiplier multiplier-value


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The multiplier-value variable is a numerical value in the following range: 2 to 120. This value is used to produce a sticky-age value for the virtual server it is configured under that is a multiple of

the value configured globally for the Brocade Virtual ADX as described in “Setting the sticky age” on page 37. For example, if the sticky age is configured to be 20 minutes, and the sticky-age-multiplier

to be 40, then the actual sticky age of the sticky sessions for the server will be 20x40= 800 minutes.

Note that even though the sticky-ages are multiplied, the show session command will still only show ordinary age of the sticky sessions. The difference is that the age is incremented in a slower pace when multiplier is applied. For example if the sticky-age-multiplier is configured to be 40, the age counter in the session table is incremented once in 40 minutes instead of 1 minute.

NOTE

You can remove the multiplier by using the sticky-age-multiplier 1 or no sticky-age-multiplier number command.

Sticky connection return from backup server to primary

You can designate real servers as primary servers or backup servers. A primary server is used by the Brocade Virtual ADX when load balancing client requests for an application. A backup server is used by the Brocade Virtual ADX only if all the primary servers are unavailable for the requested application.

In a configuration where one real server is configured as a primary server and another is configured as a backup, the virtual server can have the sticky option enabled, which ensures that new connections are sent to the primary server, and a sticky session to a given port is created that points to that primary server.

If the primary server goes down, new connections are sent to the backup server, and a sticky session to the port is created that points to the backup server. The sticky session to the

(inoperative) primary server is deleted. When the primary server becomes operative again, since the sticky session to the backup server is still valid (that is, it has not aged out), new connections to the port are still sent to the backup server. This is the default behavior.

You can optionally configure the Brocade Virtual ADX to send new connections for the port to the primary server when it comes back up, even though there is a sticky session to the backup server.

To do this for the DNS port on virtual server v1, enter the following commands.


Virtual ADX(config-vs-v1)#port dns lb-pri-servers

Virtual ADX(config-vs-v1)#port dns sticky

Virtual ADX(config-vs-v1)#port dns active-primary-overide-sticky

Syntax: port port active-primary-overide-sticky

When the active-primary-overide-sticky command is configured, if the primary server goes down and then comes back up, any new connection to the DNS port is sent to the primary server. The old sticky session to the backup server is deleted, and a new sticky session to the primary server is created.

Group sticky: Layer 4 SLB to server group

Layer 4 load balancing to server groups is performed through a Group Sticky function. This sticky behavior supports Group Sticky and Group Failover functionality.


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Enabling group sticky

The group sticky feature enables sticky connections to be load balanced among servers in the same group. Without this feature, normal sticky behavior always sends a specific client IP to a specific server. Group Sticky is useful when the server farm is grouped into clusters, and each cluster has servers with replicated (mirrored) content.

To enable Group Sticky, use the port type group-sticky command.


Figure 8 shows two server groups: group-id 1 1 and group-id 2 2. The configured VIP is serving the

clients and load balancing traffic across the servers in their respective groups.

FIGURE 8 Group sticky sample topology

40

When a client first enters the system, the Brocade Virtual ADX inspects the defined groups, predictors, and chooses a server within a group to create a sticky session. When a new connection comes in from the same client and group sticky is configured, the Brocade Virtual ADX will find all the servers belonging to the group and will load balance among the servers.

Perform the following steps.

1. Set up the real servers and group IDs. The rs1 and rs2 are in group 1. The devices Web1,

Web2, and Web3 are in group 2.

server real rs1 10.20.1.40

port http

port http url "HEAD /"

port http group-id 1 1 server real rs2 10.20.1.41

port http


port http group-id 1 1 server real Web1 10.20.1.42


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port http



port http



port http


port http group-id 2 2

2. On the VIP, ensure the minimum required commands for Group Sticky are present: port type group-sticky and port type sticky. If stickiness is not configured, load balancing among the group will not work.

Virtual ADX(config-vs-v1)#server virtual-name-or-ip vip1 10.40.1.10

Virtual ADX(config-vs-vip1)#predictor round-robin

Virtual ADX(config-vs-vip1)#port http sticky !(or port http client-subnet-sticky)

Virtual ADX(config-vs-vip1)#port http group-sticky

Virtual ADX(config-vs-vip1)#bind http rs1 http rs2 http Web1 http Web2 http

Virtual ADX(config-vs-vip1)#bind http Web3 http

Once a group sticky session is created, all subsequent traffic will be load balanced across the group. The first incoming sticky session will go to a real server in group 1. All subsequent connections will also go to group 1.

If multiple clients are in the same subnet, then use the port http client-subnet-sticky command instead of port http sticky. The group sticky behavior will apply itself to the client-subnet-sticky.

NOTE

When a real server’s port is part of two groups, the group-sticky feature takes the first listed group ID only, if the first connection is load balanced to this server.


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.

3. Identify what server the sticky session is pointed to. In the example below, the sticky session was originated from the client 10.30.1.1 to the VIP 10.40.1.10 using real server rs1. All the traffic to/from the client is being load balanced across the group (group-id 1 1) to which the real server rs1 belongs. Enter the show session all 0 command (at the BP console) such as the following.

Virtual ADX#rconsole 1 1

Virtual ADX 1/1#show session all 0

Session Info:

Flags - 0:UDP, 1:TCP, 2:IP, 3:INT, 4:INVD, H: sessInHash, N: sessInNextEntry

Index Src-IP Dst-IP S-port D-port Age Next Serv Flags

===== ====== ====== ====== ====== === ==== ==== =========

0 10.30.1.1 10.40.1.10 0 80 59 000000 rs1 SLB3 H

NOTE

In most cases, an "S-port" of value "0" indicates a sticky session. Regardless of the source port

(S-port) of the connection, the sticky session will stick to Src-IP 10.30.1.1, Dst-IP 10.40.1.10, and

D-port 80 in the example.

To clear a sticky session, use the clear server session command.

Enabling group sticky failover

Normal Group Sticky behavior sends connections to a group of servers. When an entire server group is unreachable, Group Sticky Failover sends connections to a different reachable group. The sticky session is removed from the unreachable group; a connection request is forwarded to a new group, and a new sticky session is then formed with that group.

To enable group sticky failover, enter commands such as the following.

Virtual ADX(config)#server virtual-name-or-ip vip1 10.40.1.10

Virtual ADX(config-vs-vip1)#predictor round-robin

Virtual ADX(config-vs-vip1)#port http sticky

Virtual ADX(config-vs-vip1)#port http group-sticky

Virtual ADX(config-vs-vip1)#port http group-sticky-failover

Virtual ADX(config-vs-vip1)#bind http rs1 http rs2 http rs3 http rs4 http

Virtual ADX(config-vs-vip1)#bind http rs5 http

Use the required port http group-sticky-failover command in addition to port http sticky and port http group-sticky commands. The group-sticky-failover option alone will not work.

Syntax: port type group-sticky-failover

NOTE

You can also apply the server sticky-age command to a sticky group.


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Enabling a concurrent port

The concurrent feature allows a client to have sessions on different application ports on the same real server at the same time. When you enable an application port to be concurrent, the real server can open additional (“concurrent”) TCP or UDP sessions with the client using arbitrary TCP or UDP port numbers.

Although the concurrent connections attribute is similar to application groups, application groups apply to specific TCP or UDP ports that you configure on the virtual server.

NOTE


To enable an application port to be concurrent, enter commands such as the following.


Virtual ADX(config-vs-v1)#port 80 concurrent

Syntax: [no] port tcp/udp-port concurrent


The track port and track port group methods of TCP/UDP application grouping are similar. In both configurations, the Brocade Virtual ADX sends all client requests for ports within a specific set of application ports to the same real server. The two methods differ in the following way:

• In a track port configuration, the tracking applies only to the primary port, which is the first port in the list of track ports. If the client requests one of the other applications (one of the applications that is tracking the primary application) first, Brocade Virtual ADX tracking does not apply.

• In a track port group configuration, the Brocade Virtual ADX sends client requests for applications within a group to the same real server regardless of which application the client requests first.

The track and track-group commands for a port are mutually exclusive.


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Tracking primary ports

You can configure the Brocade Virtual ADX to send all client requests for a specific set of TCP or

UDP ports to the same real server as a “primary” TCP or UDP port grouped with the other ports.

The primary TCP or UDP port can be grouped with up to four additional TCP or UDP ports. Once the

Brocade Virtual ADX sends a client request for the primary port to a real server, all subsequent requests from the client for ports grouped with the primary port go to the same real server. For a configuration example and more information, refer to

“TCP/UDP application groups configuration example” on page 47.

Note that if any primary port is down for a real server, any track ports on that real server are not considered for load balancing.

NOTE

You must configure all the grouped ports to be “sticky” and bind them to all real servers involved.

NOTE

If a client requests one of the ports that follows the primary port before requesting the primary port itself, the Brocade Virtual ADX does not make the connection sticky. Only after the client requests the primary port does the Brocade Virtual ADX make subsequent requests from the client for that port or ports that track the primary port sticky.

NOTE


To configure a TCP or UDP application group, enter the following commands.





Virtual ADX(config-vs-v1)#track 80 23 69

Virtual ADX(config-vs-v1)#bind 80 r1 80 r2 80



These commands configure HTTP (port 80), Telnet (port 23), and TFTP (port 69) to be sticky.

Syntax: [no] track primary-port TCP/UDP-port [ TCP/UDP-port [ TCP/UDP-port [ TCP/UDP-port ]]]

Track port group function

In a track port group, the Brocade Virtual ADX sends client requests for applications within a group of ports to the same real server, regardless of which application the client requests first.

Up to eight ports can be grouped together using the track port group function. However, a port can be part of only one track port group. For a configuration example and more information, refer to

“TCP/UDP application groups configuration example” on page 47.

Note that if any service port is down for a real server, the track port groups on that real server are not considered for load balancing.


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NOTE

Every port in a track port group must be configured to be “sticky” and be bound to the real servers involved.

NOTE

If no track port group configured, the sticky session age is not refreshed if any data session exists.

Only the data session's age will be refreshed if the connection is still alive.

NOTE

If a track port group is configured into the VIP (i.e. for two ports), the sticky session refreshes and will not expire as long as one of the ports has an alive session.

Configuring a track port group

To configure a track port group, enter commands such as the following:





Virtual ADX(config-vs-v1)#track-group 80 69 23




Virtual ADX(config-vs-v1)#exit

In this example, the track-group command groups the HTTP port (80), TFTP port (69), and Telnet port (23) together. Whenever a client attempts to connect to a port within the port group, the

Brocade Virtual ADX ensures that all ports in the group are active before granting the connection.

Syntax: [no] track-group TCP/UDP-port...

The sticky parameter makes the TCP or UDP ports sticky. The sticky parameter must be set for all ports in the group.

After the Brocade Virtual ADX sends a client to a real server for any of these three ports, subsequent requests from that client for port HTTP, TFTP, or Telnet will go to the same real server.

Track port group health checks for real servers

The Brocade Virtual ADX enables you to configure track port groups for both virtual servers and real servers; thereby reducing the need to create large numbers of Boolean health checks.

You can track the health of multiple application ports under a real server definition. If the health of one of the application ports fails, the aggregated health will be marked as fail.

Track port group health checks co-exists with existing health checks and other features of the

Brocade Virtual ADX. If even one of the application ports under real server is not up, the track port group state will be down and the traffic will not be forwarded to any of the ports in the track port group.

A sample configuration is shown below.

Virtual ADX(config)#server real r1 10.1.1.1

Virtual ADX(config-real-server-r1) port 80



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Virtual ADX(config-rsr1) hc-track-group 80 8081 8082

In this example, the Brocade Virtual ADX now tracks health status for ports 80, 8081, and 8082. If any of these ports is down. the combined health would be marked as failed and the Brocade Virtual

ADX will not use these ports for load balancing traffic.

Sample configuration server real rs1 10.1.1.1

port http port 8081 port 8082 hc-track-group http 8081 8082

Here is the output of the show hc-track-group-state command for this feature.

Virtual ADX#show hc-track-group-state

Real Server track-group state rs1 80 8081 8082 ACTIVE

Syntax: show hc-track-group-state

NOTE

The output of the above command may be truncated. For a complete output display, use the show hc-track-group-state detail command.

Here is an example output for the show hc-track-group-state detail command.

Virtual ADX#show hc-track-group-state detail

Status of health check track groups

Real Server: rs1

Track-group: 80 8080 8081 8082

State : DOWN

Real Server: rs2

Track-group: 80 8080 8081 8082

State : ACTIVE

Enabling track ports in a track port group to unbind

By default, when a lead port of track group is unbound, it goes to the unbind (UNB) state if there is no connection on this port, although some connections on other ports of the track group exist.

When you configure the server track-group-unbind-wait-all command, it keeps the port lead port in the await-unbind (AWU) state until no connection on any port of the track group exists.

To configure the Brocade Virtual ADX to allow track ports in a track port group to unbind gracefully after the unbinding of the track group’s lead port, enter the following command:

Virtual ADX(config)#server track-group-unbind-wait-all

Syntax: [no] server track-group-unbind-wait-all

NOTE

If a port is the primary port of a track group, the port (primary port itself) cannot be unbound immediately if there is any outstanding sessions for any ports in that track group.


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TCP/UDP application groups configuration example

Normally, when the Brocade Virtual ADX selects a real server for a client’s request for a TCP/UDP port, there is no guarantee that the Brocade Virtual ADX will select the same real server for subsequent requests from the same client. In many situations, this does not present a problem.

Even when the client is requesting the same Web page or application, if the content or service is replicated on all the real servers, the client does not know or care which real server provides the content or service for each request.

However, some applications may require that the client continue to use the same real server. For example, an interactive Web site might require successive client requests to come to the same server. Other applications might require that additional TCP/UDP applications also be on the same real server. Some applications may even require the ability to open concurrent connections on the client with different TCP/UDP ports dynamically assigned by the real server.

In all of these cases, the predictor (load-balancing metric) does not ensure that the client returns to the same real server. To accommodate these types of applications, you can configure ports on a virtual server to have the following attributes:

• Sticky connections – When you add a TCP/UDP port to a virtual server, if you specify that the port is “sticky”, a client request for that port always goes to the same real server unless the sticky age timer has expired. The sticky age timer ages out inactive sticky server connections.

Possible values are from 2 through 60 minutes. The default is 5 minutes. For more

information, see “Setting the sticky age” on page 37.

• TCP/UDP application groups (using the track port function) – A “primary” TCP/UDP port is grouped with up to four additional TCP/UDP ports. After the Brocade Virtual ADX sends a client request for the primary port to a real server, subsequent requests from the client for ports grouped with the primary port go to the same real server. For more information, see

“Tracking primary ports” on page 44.

• TCP/UDP application groups (using the track group function) – Up to eight TCP/UDP ports are grouped together. After the Brocade Virtual ADX sends a client request for any of the grouped ports to a real server, subsequent requests from the client for ports in the group go to the

same real server. For more information, see “Track port group function” on page 44.

NOTE

You must configure all the ports in a TCP/UDP application group to be “sticky”.

• Concurrent connections – The real server can open additional ("concurrent") TCP/UDP sessions with the client using arbitrary TCP/UDP port numbers.

NOTE

Although the concurrent connections attribute is similar to application groups, application groups apply to specific TCP/UDP ports that you configure on the virtual server. Concurrent connections enable the real server to arbitrarily determine the TCP/UDP ports and assign them to the client.


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Figure 9 shows an example of servers configured with sticky ports and an application group. In this

example, the content on each real server is identical. However, some applications on the server require that clients use the same server for subsequent requests to the application. The virtual server is configured to make the ports sticky and to group the TFTP and Telnet ports under the

HTTP port.

FIGURE 9 Sticky ports and application group (using the track-port function) used to group TCP/UDP applications

48

To implement an application group for this example, enter the following commands.

Virtual ADX(config)#server real-name r1 10.0.1.5

Virtual ADX(config-rs-r1)#port http

Virtual ADX(config-rs-r1)#port tftp

Virtual ADX(config-rs-r1)#port telnet

Virtual ADX(config-rs-r1)#exit



Virtual ADX(config-rs-r1)#port telnet


After you enter information for the real servers, you are ready to create the virtual server. To create the virtual server, enter the following commands.





Virtual ADX(config-vs-v1)#track 80 69 23





The commands above illustrate the track port function. The sticky parameter makes the TCP/UDP ports sticky. The track command groups the Telnet port (23) and the TFTP port (69) under the HTTP port (80); the HTTP port is established as the “primary” port. After the Brocade Virtual ADX sends a client to a real server for the HTTP port, subsequent requests from that client for the HTTP, TFTP, or

Telnet port go to the same real server. Up to four ports can be grouped with the primary port.


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Primary and backup servers

2

NOTE

Because ports 23 and 69 track port 80, state information for the tracking ports (23 and 69 in this example) are based on the tracked port’s state (port 80 in this example). The state is shown in the

Ms (Master port state) field of the display produced by the show server real command. Refer to

“Displaying real server information and statistics” on page 371.

The track group function works similarly to the track port function. With the track port function, the client uses the same server for applications associated with the grouped ports, as long as the primary port is active. In contrast, with the track group function, the client uses the same server for applications associated with the grouped ports, as long as all the ports in the group are active.

After the Brocade Virtual ADX sends a client to a real server for any of the grouped ports, subsequent requests from that client for any of the grouped ports go to the same real server.

The following commands illustrate the track group function.





Virtual ADX(config-vs-v1)#track-group 80 69 23





In this example, the track-group command groups the HTTP port (80), Telnet port (23), and TFTP port (69) together. Whenever a client attempts to connect to a port within the group, the Brocade

Virtual ADX ensures all ports in the group are active before granting the connection.

The sticky parameter makes the TCP/UDP ports sticky. The sticky parameter must be set for all ports in the group.

After the Brocade Virtual ADX sends a client to a real server for any of these three ports, subsequent requests from that client for the HTTP, TFTP, or Telnet port go to the same real server.

Up to eight ports can be grouped together using the track group function. A port can be part of only one group. The track-group and track commands for a port are mutually exclusive.


The Brocade Virtual ADX has the feature where the real server is either a primary server or a backup server based on how you added it:

• A primary server is used by the Brocade Virtual ADX when load balancing client requests for an application. It is a locally attached server added using the server real-name-or-ip command or using the Web GUI equivalent.

• A backup server is used by the Brocade Virtual ADX only if all the primary servers are unavailable for the requested application. It is remotely attached and added using the server remote-name command or using the Web GUI equivalent.

You can explicitly designate a server to be a primary server or a backup server, regardless of the command you used to add it. Therefore, a primary server or backup server can be locally attached or attached through a router.


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In addition, this feature implements the primary and backup configuration on an individual VIP basis. You designate each backup server by changing the real server configurations. You do not need to designate the primary servers. You enable the feature in individual VIPs for individual application ports.

NOTE

The Brocade Virtual ADX does not differentiate between real and remote servers when the primary-backup feature is enabled. Traffic will be load balanced among primary servers (real or remote). When all primary servers are down, traffic will be load balanced among backup servers.

NOTE

Without the primary-backup feature enabled, traffic will be load balanced among real servers and when all real servers are down, traffic will be sent to remote servers.

Figure 10

shows an SLB configuration that uses locally attached and remotely attached servers.

The configuration also uses some of the servers as the primary load-balancing servers while using the other servers only as backups. Notice that one of the locally attached servers is a backup server while one of the remotely attached servers is a primary load-balancing server.

FIGURE 10 Servers configured as primaries and backups

50

By default, when this feature is enabled on a VIP and all the primary servers are unavailable, a VIP begins using the backup servers until a primary server becomes available again. When a primary server is available, the VIP uses the primary server instead. Optionally, you can configure a VIP to continue to use the backup servers even after the primary servers become available again.

To configure primary and backup servers, perform the following tasks.

1. Edit the configuration of each backup real server to designate the server as a backup.

NOTE

You do not need to designate the primary servers. The Brocade Virtual ADX assumes that all servers you do not designate as backup servers are primary servers.

2. Enable use of the primary and backup servers in individual VIPs on individual application ports. Only the VIPs and application ports for which you enable the feature use it. The other application ports within the VIP, and the other VIPs, use the locally-attached servers

(configured using the server real-name-or-ip command) as their primary servers and the


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2 remotely-attached servers (configured using the server remote-name command) as their backup servers.

Optionally, configure the individual applications on the VIPs to continue using the backup servers following a failover, instead of returning to the primary servers.

Designating a real server as a backup

By default, the virtual server uses the locally attached real servers as the primary load-balancing servers and uses the remotely attached servers as backups.

To designate a real server to be a backup server, enter the following command.

Virtual ADX(config-rs-R3)#backup

Syntax: [no] backup

In order for the backup functionality to operate, you must also apply the lb-pri-servers command.

Enabling a VIP to use the primary and backup servers

To enable a VIP to use the servers designated as backups only as backups, and use the other servers as the load-balancing servers, enter the following command at the configuration level for the VIP.

Virtual ADX(config-vs-VIP1)#port http lb-pri-servers

This command enables VIP1 to use the backup and primary servers for application port HTTP.

The port http lb-pri-servers command is needed for the backup functionality to operate, regardless of the real servers you have, local or remote. For example, even if all your real servers are local and you have one designated as backup, it will not be used as a backup unless you apply this command.

To configure the VIP and application port to continue using the backup servers even after the primary servers become available again, use the backup-stay-active parameter, as in the following example.

Virtual ADX(config-vs-VIP1)#port http lb-pri-servers backup-stay-active

Syntax: [no] port tcp/udp-port lb-pri-servers [backup-stay-active]

When configuring the backup-stay-active option you might expect that all traffic will go to the backup server even when the primary comes back up however this may not be the case in some situations as described in the following.

The client traffic is handled by either primary servers only or by the backup servers only at all times.

You can use the show server backup-associated state to see which server is currently active as shown in the following example.

Virtual ADX(config-vs-VIP1)# show server backup-associated state

Backup state info: *indicates the current selection

Virtual server: vip1 http:

Status: enabled IP: 10.1.1.100

Primary: rs1: http(Active)* Backup: rs2: http(Active)

Syntax: show server backup-associated-state [ vip-name [ application-port ]]


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The example configures load-balancing shown in

Figure 10 on page 50.

To configure the real servers, enter commands such as the following.











Virtual ADX(config)#server remote-name R4 10.10.10.40



Virtual ADX(config)#server remote-name R5 10.10.10.50



Notice that the backup command is used with servers R3 and R5.

To configure the VIP, enter commands such as the following.

Virtual ADX(config-rs-R5)#server virtual-name-or-ip VIP1 10.10.10.100

Virtual ADX(config-vs-VIP1)#port http lb-pri-servers

Virtual ADX(config-vs-VIP1)#bind http R1 http R2 http R3 http R4 http R5 http


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Designating a real server port as a backup

Backup functionality can be configured at the application port level, meaning that for a given real server, you can specify one port to be a backup and another port as a primary.

Figure 11

illustrates this feature.

FIGURE 11 Real server application ports configured as primaries and backups

In this example, real servers RS1 and RS2 are bound to a VIP. Each real server has three ports defined: HTTP, FTP, and DNS. RS1 is the primary server for HTTP and FTP, and the backup for DNS.

RS2 is the primary server for DNS and the backup for HTTP and FTP. An HTTP or FTP request will not be sent to RS2 unless the HTTP or FTP service on RS1 is down, and a DNS request will not be sent to RS1 unless the DNS service on RS2 is down.

To configure the VIP and the real servers in

Figure 11 , enter commands such as the following.



Virtual ADX(config-vs-vs1)#bind http rs1 http rs2 http

Virtual ADX(config-vs-vs1)#port http lb-primary-servers

Virtual ADX(config-vs-vs1)#port ftp

Virtual ADX(config-vs-vs1)#bind ftp rs1 ftp rs2 ftp

Virtual ADX(config-vs-vs1)#port ftp lb-primary-servers

Virtual ADX(config-vs-vs1)#port dns

Virtual ADX(config-vs-vs1)#bind dns rs1 dns rs2 dns

Virtual ADX(config-vs-vs1)#port dns lb-primary-servers


Virtual ADX(config-rs-rs1)#port http

Virtual ADX(config-rs-rs1)#port ftp

Virtual ADX(config-rs-rs1)#port dns backup

Virtual ADX(config-rs-rs1)#exit


Virtual ADX(config-rs-rs2)#port http backup

Virtual ADX(config-rs-rs2)#port ftp backup

Virtual ADX(config-rs-rs2)#port dns



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Syntax: [no] port port-name backup

Per server based real server backup

The current implementation of the backup server requires that all non-backup servers fail before

SLB directs requests to backup servers. This method might not allow for maintaining the same level of performance in the server farm. The ability to maintain the same performance level for a given service is critical for many customers.

Per server based real server backup allows the backup servers to be associated with the specified primary servers. When a primary server fails, its backup server starts processing the traffic no matter what state the other primary servers are in. This feature works with the current real server backup mechanism by providing additional control of the backup server selection.

Current backup scheme

Currently, when a primary server goes down another server is selected among the active primary servers. Until all the primary servers are down, the server is selected from the backup servers.

Additionally, the users can configure backup-stay-active to keep the server selection in the backup groups active, even when some primary servers come back up.

Per server based backup scheme

With this feature, the associated primary and backup servers back up each other, regardless of the state of the other service ports. If a backup server is associated with a primary server, they work as a pair so that each can substitute for the other when it becomes unavailable.

If the backup-stay-active is configured, the backup server continues to process the traffic even after the primary server comes up again.

Example

Primary servers: A and B

Backup servers: C and D

Backup association: C is backup of A, D is backup of B.

Condition 1: When A goes down and B is alive, the server is selected from C and B.

Condition 2: When both A and B go down, the server is selected from C and D.

Condition 3: if backup-stay-alive is not configured. When B comes up and A stays down, the server is selected from C and B.

Condition 4: if backup-stay-alive is configured, when B comes up and A stays down, the server is selected from C and D.


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Slow start of the backup and the primary servers

If the server selection predictor is least connection, the backup server can be overwhelmed by the flood of the new connections when its primary server goes down. The same is true when the primary server goes back up and starts to take over the connections from the backup server. The slow start mechanism will be used whenever the switching of the backup or primary server happens, to give the server the chance to ramp up.

The slow start mechanism of the backup or the primary server will be the same as the one currently being used for the new servers. The slow start parameters are configured on the real server port.

NOTE

The slow start is enabled by default.

One backup per primary port or server

There will be the following restrictions:

• At the real port mode, the primary and backup ports have a one-to-one relationship. That is, the primary port can only be backed up by one backup port, and the backup port can only back up one primary port.

• At the real server mode, the primary and backup servers have a one-to-one relationship. That is, the primary server can only be backed up by one backup server, and the backup server can only back up one primary server.

The back port has the precedence over the back server

When both the port and the server backup are configured, the port configuration takes precedence over the server configuration.

For instance, the following is configured:

• The server C is the backup of the server A.

• The port 8080 of the server C is the backup of the port 8080 of the server B.

Then, the port 8080 of the server C becomes the backup of the port 8080 of the server B, but not the backup of the port 8080 of the server A.

Real server backup commands

•

“Server backup association” on page 55

•

“Server port backup association” on page 56

•

“Display the backup bindings” on page 57

Server backup association

This command is to configure the backup server for a particular primary server, in the real server mode.

Syntax: [no] backup [ server-name ]


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Example

To configure the real server R2 as the backup of the real server R1.

Virtual ADX(config)#server real-name R1 10.10.10.10




Virtual ADX(config-rs-R2)#backup R1



Server port backup association

This command is to configure the backup server port for a particular primary server port, in the real server port mode.

Syntax: [no] port port-name backup server-name port-name

Example

To configure the http port of the real server R2 as the backup of the http port of the real server R1.






Virtual ADX(config-rs-R2)#port http backup R1 http


NOTE

When both server backup and server port backup are configured, the server port backup has the precedence over the server backup.

Example












The server R3 will be the backup of R2, while the HTTP port on R3 will be the backup of the HTTP port on R1.


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Configuring Direct Server Return

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Display the backup bindings

This command is used to display the binding relationship between the servers and the ports.

Syntax: show server backup-server-port-binding

Example









Virtual ADX(config)#show server backup-server-port-binding

Server/Port State - 0: disabled, 1:enabled, 2:failed, 3:test, 4:suspect,

5:grace_dn, 6:active

Real Server rs3:(state 6)

Backup Server : rs2(state 6)

Port 80(state 6) <---------- Port rs2:80(state 6)


In some Brocade Virtual ADX implementations both client-to-server and server-to-client traffic flow through Brocade Virtual ADX. In such configurations, the Brocade Virtual ADX uses two sessions for each connection: one session for the client-to-server traffic and a second session is for the server-to-client traffic.

Direct Server Return (DSR) configurations enhance server response times and increase capacity on the Brocade Virtual ADX by allowing server responses (server-to-client traffic) to bypass the

Brocade Virtual ADX.

Direct Server Return may be used in many different Brocade Virtual ADX implementations. For example, it can be used on a single Brocade Virtual ADX supporting a single server farm or applied to multiple Brocade Virtual ADX devices in the Hot Standby high availability (HA) scenario.


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FIGURE 12 Two Brocade Virtual ADX device s in an DSR configuration

58

Brocade Virtual ADX supports both Layer 2 Direct Server Return (L2 DSR) and Layer 3 Direct Server

Return (L3 DSR). The steps required to configure support L2 DSR and L3 DSR differ significantly.

• In an L2 DSR configuration, the Brocade Virtual ADX and the real servers must be on the same subnet.

• In an L3 DSR configuration, the Brocade Virtual ADX and the real servers can be connected by a router.

Configuring L2 Direct Server Return

A Brocade Virtual ADX configured for L2 DSR acts as a dispatcher, sending client requests for a VIP directly to the real server, which responds directly to the client. The Brocade Virtual ADX does not translate the destination IP address in the client’s request from the VIP into the real server’s IP address as in other SLB configurations. Instead, the Brocade Virtual ADX leaves the destination IP address unchanged.

NOTE

In an L2 DSR configuration, you cannot router hop between the Brocade Virtual ADX devices. They must have Layer 2 connectivity.

Two changes must be implemented to support L2 DSR:

• Support for L2 DSR must be enabled on individual TCP/UDP ports when you configure the virtual server (DSR VIP).

• A loopback address must be configured on each real server and the appropriate VIP address must be assigned to that loopback interface.


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Enabling L2 DSR on TCP/UDP ports

To configure the Brocade Virtual ADX for L2 DSR, you must enable the feature for individual

TCP/UDP ports when configuring the virtual server.

For example, when you enable TCP port 80 (HTTP) on a virtual server, you can add the DSR parameter to enable L2 DSR for that port.


Virtual ADX(config-vs-v1)#port 80 dsr

Traffic for other ports still returns through the Brocade Virtual ADX. The Brocade Virtual ADX does not translate the destination IP address in client requests for the port with L2 DSR enabled.

However, the Brocade Virtual ADX still translates the destination IP address in the client’s request to the real server’s IP address for other ports.

Syntax: [no] port tcp/udp-port dsr

Configuring the loopback address on a real server

To configure the real servers for L2 DSR, configure a loopback interface on each real server and assign the VIP addresses to the loopback interface.

The loopback interface enables the real server to respond to client requests directed at the VIPs, while at the same time keeping the real server “hidden”. The loopback interface responds to unicast traffic directed to it, but does not respond to ARP requests. The Brocade Virtual ADX responds to pings and ARPs for the VIPs. Thus, any attempt to obtain the real server’s MAC address using ARP protocol does not succeed.

You can configure loopback addresses on some common types of real servers. Refer to the

“Server-specific Loopback Configurations” on page 349 for details.

Health checks with L2 DSR

Normally, the Brocade Virtual ADX can perform health checks on an application port only when a server replies from that port pass back through the Brocade Virtual ADX. If the Brocade Virtual ADX does not see the real server’s responses to client requests, the Brocade Virtual ADX concludes that the application or the entire server is down and stops sending client requests to that server.

When you enable an application port for DSR, the Brocade Virtual ADX can still perform heath checks on the application by sending the health checks to the loopback address you configure on the real server.

You can use Layer 4 and Layer 7 health checks in your DSR configuration.

• The Brocade Virtual ADX addresses Layer 3 (IP ping) health checks to the real server IP address.

• The Brocade Virtual ADX addresses Layer 4 and Layer 7 health checks to the real server MAC address and to the loopback address that matches the VIP address.

The configuration procedures for the health checks are the same as for other types of SLB. Refer to

Chapter 4, “Health Checks”

.


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Placing a session in delete queue

DSR fast delete places a session in a delete queue upon seeing the first FIN in Direct Server Return

(as opposed to the standard two FINs). The session is deleted in eight seconds instead of the standard two minute FIN session age.

The DSR fast-delete option is enabled by default. To disable the option, enter commands as follows:

Virtual ADX(config)#server virtual-name-or-ip vs

Virtual ADX(config-vs-vs)#port 80 dsr no-fast-delete

Syntax: [no] port port dsr no-fast-delete

NOTE

The default setting is recommended in most cases. In the DSR setup, the Brocade Virtual ADX will not be able to see a FIN message from a server, resulting into session piling up and connection drops when the same TCP connection is reused within two minutes by a client.

L2 DSR configuration example

Direct Server Return may be used in many different Brocade Virtual ADX implementations including

the Hot Standby high availability (HA) scenario. Figure 13 shows an example of an L2 DSR

configuration for an HA scenario.

FIGURE 13 Brocade Virtual ADX device s deployed in Direct Server Return configuration


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To implement the configuration shown in Figure 13 , configure Brocade Virtual ADX devices A and B.

Because multiple VIPs are mapped to the same ports on the same real servers, TCP/UDP port binding is used. Thus, port 180 on VIP2 on Brocade Virtual ADX A and on VIP1 on Brocade Virtual

ADX B is a logical port that is bound to port 80 on the real servers. For more information, refer to


TABLE 7

Brocade

Virtual ADX

DSR configuration example

Domain name Virtual IP (VIP) address

VIP’s TCP port

Real IP address Real Server TCP port

A www.abc.com

VIP1:

10.157.22.100

80 Real Server 1:

10.0.0.1

80

A www.def.com

VIP2:

10.157.22.101

80

Real Server 2:

10.0.0.2

Real Server 1:

10.0.1.1

80

180

180

B

B www.abc.com

www.def.com

VIP1:

10.157.22.100

VIP2:

10.157.22.101

80

80

Real Server 2:

10.0.1.2

Real Server 3:

10.0.0.1

Real Server 4:

10.0.0.2

Real Server 3:

10.0.1.1

Real Server 4:

10.0.1.2

180

180

80

80

Note the dsr parameter on the port commands that add the HTTP port (TCP port 80) to the VIPs. To enable L2 DSR for additional TCP/UDP ports, use the dsr parameter for each port when you add the port to a VIP.

NOTE

Be sure you configure all the real servers on both Brocade Virtual ADX devices, and bind the VIPs on each Brocade Virtual ADX to all the real servers.

Configuring Brocade Virtual ADX A

Notice that all four real servers must be configured, and bound to the VIPs, on both Brocade Virtual

ADX devices. Notice also that two HTTP ports are added to each real server. This type of configuration requires that you use the TCP/UDP port binding feature to bind the ports on the two

real servers to the same port on the virtual server. For information, refer to “Multiple port binding” on page 69.

To configure the real servers, enter the following commands.

Virtual ADXA(config)#server real-name Real_Server_1 10.0.0.1

Virtual ADXA(config-rs-Real_Server_1)#port http

Virtual ADXA(config-rs-Real_Server_1)#port 180

Virtual ADXA(config-rs-Real_Server_1)#exit





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To configure the VIPs, enter the following commands.

Virtual ADXA(config)#server virtual-name-or-ip VIP1 10.157.22.100

Virtual ADXA(config-vs-VIP1)#port http dsr

Virtual ADXA(config-vs-VIP1)#bind http Real_Server_1 http Real_Server_2 http

Real_Server_3 http Real_Server_4 http

Virtual ADXA(config-vs-VIP1)#exit

Virtual ADXA(config)#server virtual-name-or-ip VIP2 10.157.22.101

Virtual ADXA(config-vs-VIP2)#port http dsr

Virtual ADXA(config-vs-VIP2)#bind http Real_Server_1 180 Real_Server_2 180

Real_Server_3 180 Real_Server_4 180

Virtual ADXA(config-vs-VIP2)#no http port translate

Virtual ADXA(config-vs-VIP2)#exit

Virtual ADXA(config)#write memory

Configuring Brocade Virtual ADX B

To configure the real servers, enter the following commands.

Virtual ADXB(config)#server real-name Real_Server_1 10.0.0.1

Virtual ADXB(config-rs-Real_Server_1)#port http

Virtual ADXB(config-rs-Real_Server_1)#port 180

Virtual ADXB(config-rs-Real_Server_1)#exit













To configure the VIPs, enter the following commands.

Virtual ADXB(config)#server virtual-name-or-ip VIP1 10.157.22.100

Virtual ADXB(config-vs-VIP1)#port http dsr

Virtual ADXB(config-vs-VIP1)#bind http Real_Server_1 180 Real_Server_2 180

Real_Server_3 180 Real_Server_4 180

Virtual ADXB(config-vs-VIP1)#no http port translate

Virtual ADXB(config-vs-VIP1)#exit

Virtual ADXB(config)#server virtual-name-or-ip VIP2 10.157.22.101

Virtual ADXB(config-vs-VIP2)#port http dsr

Virtual ADXB(config-vs-VIP2)#bind http Real_Server_1 http Real_Server_2 http

Real_Server_3 http Real_Server_4 http

Virtual ADXB(config-vs-VIP2)#exit

Virtual ADXB(config)#write memory


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Configuring L3 Direct Server Return

In an L3 DSR configuration, the Brocade Virtual ADX marks all packets sent to servers bound to a specified VIP (the L3 DSR VIP) by setting the DSCP field to a configured value.

The real server must be programmed to check the DSCP field of incoming packets and change the source IP address of appropriate reply packets from its own IP address (real IP address) to the virtual IP address (VIP).

Three changes must be implemented to support L3 DSR:

• TOS marking of SLB and health check packets: All SLB and health check traffic sent to servers bound to a specified VIP must be marked by a specific DSCP field value. Use the tos-marking command to specify the DSCP field value.

• Special intelligence on real servers: The real server must be programmed to check the DSCP field of incoming packets and change the source IP address of appropriate reply packets from its own IP address (real IP address) to the virtual IP address (VIP).

• Special intelligence for handling health check responses: To enable the Brocade Virtual ADX to correctly handle health check replies you must configure hc-l3-dsr under the VIP using the tos-marking command with the hc-l3-dsr option.

TOS marking of SLB and health check packets

To configure the Brocade Virtual ADX for L3 DSR, the Brocade Virtual ADX must set the DSCP field value in all packets sent to servers bound to a specified VIP.

Use the tos-marking command within a VIP configuration to specify the DSCP field value of traffic packets send to real servers bound to a specific VIP.


Virtual ADX(config-vs-vip1)#tos-marking 18


The Brocade Virtual ADX sets the DSCP field value to 18 in all packets sent to real server rs1.

Use the hc-l3-dsr option to ensure that Brocade Virtual ADX will process the health check reply packets correctly:


Virtual ADX(config-vs-vip1)#tos-marking 18 hc-l3-dsr


Although the Brocade Virtual ADX will have sent health check probes to the real server IP, it will receive replies from the VIP. The hc-l3-dsr option ensures that responses from a different IP address are handled correctly.

Syntax: tos-marking DSCP-value hc-l3-dsr

The DSCP-value variable specifies the value of the DSCP field that you want to send to all packets sent to servers bound to the VIP.

With the hc-l3-dsr option configured the health check reply packets will be sent back to the VIP on the Brocade Virtual ADX.


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Special handling by real servers

L3 DSR requires special intelligence on the real server. Real servers must be programmed to check for DSCP field values in incoming packets and, if the received DSCP value matched a preconfigured value, change the source IP address of reply packets from its own IP address (real-ip) to a virtual IP address (virtual-ip).

Health checks with L3 DSR

When TOS marking is configured, all health check packets to servers bound under a VIP will have

DSCP field set with a configured value. If special handling is enabled on the real servers, reply packets will come from VIP instead of the real server IP. For the Brocade Virtual ADX to process these reply packets correctly, you must configure tos marking using the hc-l3-dsr option.

With the hc-l3-dsr option configured the health check reply packets will be sent back to the VIP on the Brocade Virtual ADX. If you have the tos-marking command configured without this option, if a reply packet has the VIP as its source IP address, health checks will fail and the packet will be dropped.

The tos-marking hc-l3-dsr command implicitly enables DSR fast-delete. Hence, the option expedites deleting DSR SLB sessions when the Brocade Virtual ADX receives a first TCP FIN message from a client; this behavior is similar to dsr fast-delete for L2 DSR. For information, refer to

“Placing a session in delete queue” on page 60.

NOTE

Only TCP is supported with L3 DSR health checks. For UDP and ICMP health checks, the Brocade

Virtual ADX does not mark the DSCP field.

L3 DSR configuration example

To enable Layer 3 DSR, you must configure a Brocade Virtual ADX to set the DSCP field to a configured value in all packets sent to servers bound to a specified VIP (L3 DSR VIP).

Use the tos-marking command with the hc-l3-dsr option under the VIP to set the DSCP field to a configured value. The hc-l3-dsr option makes the Brocade Virtual ADX to accept health check packets coming from the L3 DSR VIP rather than the real server IP address.

To enable Layer 3 DSR, perform the following steps.

1. Configure a real server as a remote server because it is not connected to any VLANs on the


Virtual ADX(config)#server remote-server rs1 10.20.1.31



2. Define an SLB VIP and make it to an L3 DSR VIP by configuring the tos-marking command and hc-l3-dsr option.


Virtual ADX(config-vs-vip1)#tos-marking 20 hc-l3-dsr

In this example, Brocade Virtual ADX sets the DSCP value to 20 in all packets, either for health check or server load balancing, sent to real server rs1. Note that ADX is not configured with source-nat even though you have a remote server.


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NOTE

To make the above configuration work, the real server must have a special intelligence. When the server receives a packet with DSCP value 20, it should use "10.1.1.151" as a source IP address in response packets.

NOTE

When DSR is configured, the server directly responds to the client, therefore, if the user binds different real server ports and virtual server ports, e.g. port 8080 of real server to port 80 of virtual server, the DSR traffic will not work.

Displaying server information

The show server command, as a standalone command, gives the output of the following commands together:

•

show server global - Refer to “Displaying global Layer 4 Brocade Virtual ADX configuration” on page 368.

• show server bind - Refer to

“Displaying port-binding information” on page 381.

•

show server sessions - Refer to “Displaying port-binding information” on page 381.

• show server traffic - Refer to

“Displaying packet traffic statistics” on page 384.

The show server global command gives the output of the show server backup command.

Port ranges

Port ranges can be defined under real servers or virtual servers. Port ranges can be used with bind statement under VIP. Additionally, you can define port profiles for a port range and specify characteristics such as TCP or UDP, keepalive timers, retires for all ports inside port range.

NOTE

Port-policy definition is not supported with port range. This is because all ports inside a port range must have the same characteristics, and these characteristics can be defined using port profile.

The Brocade Virtual ADX processes client requests destined to ports inside a port range in the same way it processes connections to individual ports.


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Port ranges

Defining a port range

Port ranges are identified by their names. A port range can be created as follows.

1. Define the port range

Virtual ADX(config)#port-range pr1

Syntax: [no] port-range port-range-name

2. Identify the ports in the range.

Virtual ADX(config-pr-pr1)#port 8051 to 8100

Syntax: [no] port port-number to port-number

Enter the port’s numerical value for port-number.

When defining a port range:

• Ports in a port range must be consecutive.

• You must define a starting port and an ending port for the range.

• The starting port must be greater than zero (0).

• The ending port must be larger than the starting port.

• There can be up to 50 ports in a port range.

• You can change the starting port and ending port using a single command. When changing the ports in a port range, if the port range is not used with a bind statement or other configuration, then the change is applied immediately; otherwise, the change remains pending until the apply port-range command is issued.

• You cannot include the default port (65535) and well-known ports in a port range.

• Furthermore, if role-based management is used, only the super user or global manager can create port ranges at the global configuration level. Role-based users can use port ranges and bind them under the real server and virtual server configuration levels. Also, role-based users can view the list of port ranges by issuing the show port-range command.

• If you define many port ranges to cover many application ports (several hundreds or thousands of ports) then you need to keep an eye on MP CPU resources, because a system might not be able to handle health checks for all these ports. Disabling of health checks for several ports or port-ranges might be needed in such cases to prevent health check issues.

• Port ranges cannot be used with alias port ("real-port") definitions.

• Some of the other features not supported with port range are: Multiple port binding, PBSLB, boolean health check, scripted health check, track-groups, track-ports, tcp offload, and keepalive.


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Using a port range under a real server definition

You can define port ranges under a real server definition.

Virtual ADX(config)#server real real1 10.0.0.1

Virtual ADX(config-rs-real1)#port-range pr1


Enter the ID of the port range for port-range-name

. Refer to the rules in “Defining a port range” on page 66 for additional rules.

You can add more than one port range to a real server; however, the ports in the port ranges cannot overlap. For example, if you define PR1 to include ports 8051 to 8100 and define PR2 to include ports 8061 to 8110, then you cannot use these two port ranges under the same real server because ports are overlapping. Also, if a port is included inside a port range and that port range is specified under real server, then the port cannot be specified separately under same real server.

All commands available to a single application port are available to the ports in a port range. For example, you can configure keepalive for a port range as you would for a single port.


Virtual ADX(config-rs-rs1)#port-range pr1 keepalive

Using a port range under a virtual server definition

You can define a port range under a virtual server.

Virtual ADX(config)#server virtual-name-or-ip virtual1 10.0.0.1

Virtual ADX(config-vs-virtual1)#port-range pr1


Enter the ID of the port range for port-range-name .

The rules for including port ranges to a real server also apply to a virtual server. (Refer to

“Using a port range under a real server definition”

.)

Binding a port range for virtual ports to a real server

You can bind a port range from under a virtual server to real servers. Binding a port range is equivalent to binding all ports contained in the port range to the specified real server. All rules that apply to single port bindings also apply to binding port ranges. In addition, you can bind different port ranges to a virtual server if the port ranges each have the same number of ports.

The binding is a one-to-one mapping, where the starting port in the virtual server port range is bound to the starting port in the real server port range. The second port in a virtual server port range is bound to the second port of a real server port range.



Virtual ADX(config-pr-pr1)#exit



Virtual ADX(config-pr-pr2)#exit

Virtual ADX(config)#server virtual-name-or-ip virtual1 10.0.0.1

Virtual ADX(config-vs-virtual1)#bind-range pr1 realserver1 pr1 realserver2 pr2

Syntax: [no] bind-range port-range-name real-server-name port-range-name


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Port ranges

Defining port profile for port range

You can define a profile for a port range. Policies and other features defined for a port profile are applied to all the ports included in the port range.

Virtual ADX(config)#server port-profile port-range pr1

Virtual ADX(config-port-profile-range-pr1))#tcp keepalive use-master-state

Syntax: [no] server port-profile port-range port-range-name

The following commands are available under the port-profile-range configuration level:

• bringup-retries

• disable

• l4-bringup-interval

• l7-bringup-interval

• no-fast-bringup

• tcp

• udp

When defining a port profile for a port range, note the following:

• A separate port profile for an individual port inside a port-range definition is not permitted. All ports inside a port-range must have the same properties.

• In the case of overlapping port ranges that are used under different real servers, a port profile for only one of the port ranges is allowed. You cannot have conflicting properties for the same port under different port ranges.

Displaying a list of port ranges

You can display a list of port ranges that have been created in the Brocade Virtual ADX by issuing the following command.

Virtual ADX(config)#show port-range

Syntax: show port-range [ start-index ]

Issuing the show port-range command displays information for all the port ranges configured on the Brocade Virtual ADX. To limit the number of port ranges included in the output, issue the show port-range start-index command. Information only for the port ranges starting from the specified start-index is displayed.

.

Virtual ADX#show port-range

Name Start End Pending Start Pending End RefCnt

pr2 8090 8139 500

pr3 8140 8149 100

pr98 9800 9803 4

range4 7001 7050


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Using a start-index variable begins display at the record specified where the first record has a value of 0. In the following example, the start-index value of 2 is used on the same port-range displayed in the previous example.

Virtual ADX(config)#show port-range 2

Name Start End Pending Start Pending End RefCnt pr98 9800 9803 4 range4 7001 7050

To display a list of port ranges with a name that starts with a specified prefix, issue the following command.

Virtual ADX(config)#show port-range starts-with pr

Syntax: show port-range starts-with prefix

Virtual ADX#show port-range starts with pr

Name Start End Pending Start Pending End RefCnt

pr2 8090 8139 500

pr3 8140 8149 100

pr98 9800 9803 4

The

Table 8 describes the information in the output.

TABLE 8

Field

Field descriptions of show port-range command

Description

Name

Start

End

Pending Start

Pending End

RefCnt

Name of the port range

First port in the port range

Last port in the port range

The port range has been changed but the apply port-range command has not been issued. This column shows the start of the new port range.

The port range has been changed but the apply port-range command has not been issued. This column shows the end of the new port range.

This field is used by developers for debugging purposes.


Multiple port binding allows you to bind one real server port to multiple virtual server ports.

The Brocade Virtual ADX supports two methods of associating a real server TCP or UDP port to multiple virtual TCP or UDP ports (VIPs): direct binding of multiple ports and port aliases.

• Direct binding of multiple ports enables to you to associate a real server TCP or UDP port directly to multiple virtual TCP or UDP ports. Using this method you do not need to configure additional alias ports for real ports or virtual ports in order to bind a single real server to multiple virtual servers; nor are alias ports needed to bind a real server to multiple virtual ports on a single virtual server.

• Port aliases bind a real server TCP or UDP port to multiple port aliases, which are bound to the virtual ports.

Although the Brocade Virtual ADX supports both direct binding of multiple ports and port aliases, the two methods cannot co-exist for the same real port or virtual port.


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To simplify an existing configuration that uses port aliases, you can manually convert that configuration to the direct binding method to reduce the size of SLB configurations. If you choose to use the direct method, you must first remove all alias port bindings and reload your configuration.

Direct binding of multiple ports

Direct binding of multiple ports enables you to associate a real server TCP or UDP port with multiple virtual TCP or UDP ports.

Binding a real server port to multiple VIPs

To bind one real server port (rs1) to multiple VIPs (vs1 and vs2), complete the following steps:

1. Create a real server with one port.



2. Create a virtual server.


3. Create an HTTP port on the virtual server.


4. Bind the real port on the real server to the HTTP port on the virtual server.

Virtual ADX(config-vs-vs1)#bind http rs1 http

5. Repeat the steps 2 through 4 for each additional virtual server.

.



Virtual ADX(config-vs-vs2)#bind http rs1 http

Configuration rules

Although both direct binding of multiple ports and port binding of multiple ports via port aliases are supported by the Brocade Virtual ADX, the two configurations cannot co-exist for the same real port or virtual port.

A real server port cannot be bound to a virtual port if any of the following conditions are met:

• The real port is already bound to another virtual port as an alias port.

• The virtual port has been bound to an alias port.

• The virtual port is configured for stateless or stateless fragmentation support. For more

information, see “Fragmentation support in the stateless mode” on page 157.

• The virtual port is configured for persistent hashing. For more information, see

“Enabling persistent hashing” on page 87.

When a real port is bound to multiple virtual ports, the following configurations are not allowed:

• A virtual port with a multiple port binding cannot be bound as an alias port.

• The real port cannot be bound as an alias port or use another port as an alias port.

• The virtual port cannot be configured for stateless or stateless fragmentation support.

• The virtual port cannot be configured for persistent hashing.


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NOTE

The default port (a port the Brocade Virtual ADX automatically configures on all real and virtual servers) and the source IP application port do not support multiple port binding.

Specifying the number of multiple port bindings available

Direct binding of multiple ports is enabled by default with the default value for the number of bindings allowed as determined by the license that is active on your system. Use the system-max l4-multi-binding command to change the number of multiple port bindings available or disable multiple port binding.

Syntax: system-max l4-multi-binding new_max

The new_max variable identifies the number of multiple port bindings that can be created. The minimum, maximum and default values are determined by the license that is active on your system. For actual values associated with your license, refer to the Brocade Virtual ADX Licensing

Guide . If the new_max value is set to 0, support for multiple port binding is disabled.

Whenever you specify the number of multiple port bindings, you must restart the system if you change the new_max value to a different non-zero value. If reloading the system is not an option, you must remove all additional multiple port bindings before changing the new_max value.

The show server resource command displays the number of multiple port bindings, as shown in the following example.

Virtual ADX#show server resource

Server resource usage: l4-real-server l4-virtual-server l4-server-port l4-multi-binding

Current Maximum

2

2

256

32

8

1

2048

8192

The number of configured server ports and configured multiple port bindings can be captured by an SNMP trap when a certain threshold is reached.

In the output of the show server bind command, each additional binding is displayed with a + sign appended to it.

Virtual ADX#show server bind

Bind info

Virtual server: vs1 Status: enabled IP: 10.1.2.100

http -------> rs1: 10.1.2.1, http (Active)

rs2: 10.1.2.2, http (Active)

Virtual server: vs2 Status: enabled IP: 10.1.2.101

http -------> + rs1: 10.1.2.1, http (Active)

+ rs2: 10.1.2.2, http (Active)


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Port aliases

When you associate a virtual port (VIP) with a real server, you make the association for a particular

TCP or UDP port. The association of a TCP or UDP port on a VIP with a TCP or UDP port on a real server is called a "port binding".

In most configurations, only one VIP-to-real-server binding is made for a TCP or UDP port. For example, if you bind VIP 10.29.2.2 to real server 10.0.0.1 for port 80 (the well-known HTTP port), you do not generally create any other bindings between VIP 10.29.2.2 and real server 10.0.0.1 for the same port. However, should you wish to track statistics for multiple applications or domain names mapped to the same real server port, you can do so by creating multiple port bindings.

One method of binding a single real server port to multiple VIPs is to configure a port alias for each additional VIP. For example, if you want to associate three VIPs with the same real server, you can define two TCP or UDP port aliases, one for each of the additional VIPs.

In such a configuration, the Brocade Virtual ADX collects and displays statistics and configuration information individually for each VIP, but sends all traffic to the same TCP or UDP port number on the real server.

Binding same real ports to multiple VIP ports

Multiple port binding enables a real server port to be bound to multiple VIP ports, which is useful when you want to bind multiple VIPs to a single application service on real servers, and the real servers are listening on different ports.

NOTE

This command is backward-compatible with the real-port command.

To bind multiple ports to one real server port, follow these steps.

1. Create a real server with two ports.

Virtual ADX(config)#server real rs1

Virtual ADX(config-rs-rs1)#port 81

Virtual ADX(config-rs-rs1)#port 8081 <- alias port

2. Create a second real server with two ports.



Virtual ADX(config-rs-rs2)#port 8082 <- alias port

3. Create a virtual server.

Virtual ADX(config)#server virtual-name-or-ip vs1

4. Configure an HTTP port on the virtual server.


5. Bind the alias ports to the real servers on the virtual servers.

Virtual ADX(config-vs-vs1)#bind http rs1 81 rs2 82

6. Create a second virtual server with an HTTP port.




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7. Bind the alias ports to the real servers on the virtual servers.

Virtual ADX(config-vs-vs2)#bind http rs1 8081 real-port 81 rs2 8082 real-port

82

Syntax: bind virtual-port real-server-name alias-port [real-port real-port-num ]

NOTE

Alias ports should be treated like regular ports and should have the same server ID and group ID.

Binding a real server port to multiple VIPs for port translation

You can bind a real server port to multiple VIP ports with or without port translation. Port translation is useful in cases where different client groups require different VIPs.

The real-port option has been added to the existing port virtual subcommand.

Syntax: [no] port tcp/udp-port real-port real-server-port-to-use

NOTE

This feature takes precedence over the no port port translate virtual subcommand.

In the following examples, notice that alias port 8081 is defined for binding between the real server and virtual server. The alias port and the real-port work together.

To bind one real server port to multiple VIPs (vs1 and vs2), enter commands such as the following.

server real rs port 8080 port 8080 l4-check-only port 8081 <---- alias port port 8081 l4-check-only server virtual-name-or-ip vs1

port http

bind http rs 8080 server virtual-name-or-ip vs2

port http

port http real-port 8080

<---- use real port 8080 to do port translation

bind http rs 8081

<--- bind to alias port

.

.

To bind one real server port to multiple virtual ports of one VIP, enter commands such as the following.

server real rs port 8080 port 8080 l4-check-only port 8081 <---- alias port port 8081 l4-check-only server virtual-name-or-ip vs

port http

bind http rs 8080

port 81

port 81 real-port 8080

<---- use real port 8080 to do port translation

bind 81 rs 8081

<---- bind to alias port


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Configuration rules

Use the following rules when configuring the Brocade Virtual ADX to bind more than one virtual server to the same real server using the same application port:

• You must configure both the real port and the alias port on the real servers. For example, if you need to create alias port 180 so that you can bind two virtual servers to the same real server and application port (80) on a real server, you must configure port 80 and port 180 on the real server. Otherwise, you will not be able to completely bind all the virtual servers to the real server. In the example below, the following real server configurations are incomplete because neither of the real servers has both the untranslated and alias ports configured.





Virtual ADX(config-rs-r2)#port 180


• You cannot bind to both the untranslated port and the alias port in the same bind statement. In the example below, the following bind statement is invalid.

Virtual ADX(config-vs-VIP1)#port http

Virtual ADX(config-vs-VIP1)#bind http r1 http r2 180

Here is a more detailed explanation.

When you configure SLB, one of the tasks you perform is to bind the TCP or UDP application ports on the virtual server to their counterparts on the real server. For example, if clients will be sending requests to port 80 (HTTP) on virtual server www.example8.com

, but your real servers expect the

HTTP connections to arrive on port 8080 of real server R1, you must bind port 80 on the virtual server to port 8080 on the real server.

One of the requirements is that a real server can be bound to only one virtual server using the same TCP or UDP application port. As a result, when you bind a real server port to a virtual server port, you cannot then bind the same real server port to a different virtual server port.

Normally, the Brocade Virtual ADX translates the IP address and application port of the virtual server requested by the client into the real server IP address and application port that you bind to the virtual server. However, when you disable port translation, the Brocade Virtual ADX does not perform the translation for the application port. Instead, the Brocade Virtual ADX translates the destination IP address in the client’s request to the IP address of a real server, but leaves the application port in the client’s request untranslated.


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To implement the configuration described above, enter commands such as the following.









Virtual ADX(config)#server virtual-name-or-ip VIP1 10.157.22.88


Virtual ADX(config-vs-VIP1)#bind http r1 http r2 http

Virtual ADX(config-vs-VIP1)#exit

Virtual ADX(config)#server virtual-name-or-ip VIP2 10.157.22.99


Virtual ADX(config-vs-VIP2)#no port http translate

Virtual ADX(config-vs-VIP2)#bind http r1 180 r2 180

The well-known port (80) is used for VIP1, but an alias (180) is used for VIP2. The real servers actually use port 80 for traffic to both virtual IP addresses. However, the alias port enables the ISP to distinguish among the two IP addresses and their traffic when they display SLB information on the Brocade Virtual ADX. The no port http translate command is required. This command enables the Brocade Virtual ADX to send traffic from multiple VIPs to the same real TCP/UDP port on the real server (in this example, “http” (port 80)). If you leave this command out, the Brocade Virtual

ADX does not use port 180 as an alias but instead sends the VIP traffic to TCP/UDP port 180 on the real server rather than 80.

NOTE

Because the untranslated port is logically bound to the translated port and both ports are bound to the same port on the real server, state information for the untranslated port is based on the translated port’s state. In this example, state information for port 180 is based on the state for port

80. The state is shown in the Ms (Master port state) field of the display produced by the show server

real command. Refer to “Displaying real server information and statistics” on page 371.

NOTE

You can configure the Brocade Virtual ADX to perform health checks on each VIP independently.

Refer to “Health check of multiple websites on the same real server” on page 224.


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To display statistics for the separate real IP addresses, enter the following command at any command prompt.

Virtual ADX(config)#show server real

Real Servers Info

========================

State(St) - ACT:active, ENB:enabled, FAL:failed, TST:test, DIS:disabled,

UNK:unknown, UNB:unbind, AWU:await-unbind, AWD:await-delete

HLD:held-down

Name: r1 State: Active Cost: 0 IP:10.95.7.1:1

Mac: 0000.855d.e2cd Weight: 1/1 MaxConn: n/a

Src-nat (cfg:op) = 0: 0 Dest-nat-(cfg:op) = 0: 0

Port St

180 ENB

Ms CurConn TotConns Rx-pkts Tx-pkts Rx-octet Tx-octet Reas

2 0 0 0 0 0 0 0 http ENB 0 0 0 0 0 0 0 0

Keepalive: Disabled, status code(s) default (200-299, 401)

HTTP URL: "HEAD /" defaulunbnd 0 0 0 0 0 0 0 0

Server Total 0 0 0 0 0 0 0

Name: r2 IP: 10.0.2.200 : 1 State: 3 Wt: 1 Max-conn: n/a

Src-nat (cfg:op) = 0: 0 Dest-nat-(cfg:op) = 0: 0

Port St Ms CurConn TotConns Rx-pkts Tx-pkts Rx-octet Tx-octet Reas http ENB 2 0 0 0 0 0 0 0

Keepalive: Disabled, status code(s) default (200-299, 401)

HTTP URL: "HEAD /" defaul UNB 0 0 0 0 0 0 0 0


The lines highlighted in bold indicate the separate HTTP port numbers. The two HTTP lines for real server 1 (r1) indicate that an alias is in use. The first line lists the alias port number, and the second line lists the actual port number used by the real server. Even though the same port number is used on the real server, the Brocade Virtual ADX display distinguishes the traffic for the two virtual IP addresses.

NOTE

The state of the alias HTTP port is always the same as the state of the actual HTTP port used in the packets the Brocade Virtual ADX sends to the real server. The state is shown in the Ms (Master port state) column in the show server real display. Refer to

“Displaying real server information and statistics” on page 371.

Performing SLB based on alias port state

To perform SLB based on an alias port state, enter commands such as the following.


Virtual ADX(config-vs-v1)#port 8080

Virtual ADX(config-vs-v1)#no port 8080 translate

Virtual ADX(config-vs-v1)#port 8080 use-alias-port-state

Syntax: [no] port number use-alias-port-state


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Assume a configuration having two VIPs on the same real server with different health checks for each VIP using no port translate. If the real server health check fails for the first VIP (bound to master port), traffic is not sent to the second VIP (bound to alias port). The client will receive a RST.

When port use-alias-port-state is enabled, traffic to a VIP on the alias port will be forwarded if the health of the alias port passes. This feature is useful in scenarios where master port health and alias port health are using different URLs for health check.

Enabling the Brocade Virtual ADX to use the alias port’s state

In a configuration with two VIPs bound to the same server port, where the VIPs are hosting multiple

Web sites on the same server (different VIPs point to different sites), an alias port is required. In this scenario, if the master port goes down, the Brocade Virtual ADX stops forwarding traffic to the other sites as well, even though these sites are up. This behavior occurs because the Brocade

Virtual ADX uses the master port’s state for traffic forwarding decisions. To resolve this issue, you must enable the Brocade Virtual ADX to use the alias port’s state for traffic forwarding decisions.

So, if the alias port’s state is up, the Brocade Virtual ADX continues to forward traffic. Likewise, if the alias port’s state is down, the Brocade Virtual ADX stops forwarding traffic to the server.

To enable the Brocade Virtual ADX to use the alias port’s state for traffic forwarding decisions, enter the following command.

Virtual ADX(config-vs-v2))#port http use-alias-port-state

Syntax: port tcp/udp port use-alias-port-state

In the next example, if site test1 goes down, the Brocade Virtual ADX would stop forwarding traffic to VIP2 as well. In this scenario, you would enable the port http use-alias-port-state command so that traffic to VIP2 does not stop when site test1 goes down.



Virtual ADX(config-rs-r1)#port http url "test1.html"


Virtual ADX(config-rs-r1)#port 8080 url "test2.html"

Virtual ADX(config-rs-r1)#server virt VIP1 10.10.1.121

Virtual ADX(config-vs-v1)#port http

Virtual ADX(config-vs-v1)#bind http r1 http

Virtual ADX(config-vs-v1)#server virt VIP2 10.10.1.122


Virtual ADX(config-vs-v2)#bind http r1 8080

Virtual ADX(config-vs-v2)#no port http translate

Real server groups

A real server group is a container of multiple real servers that you can use to simplify and reduce the size of your load balancing configurations.

For large scale configurations you'll want to use real server groups to avoid reaching the 1.4MB configuration file size limit set by the Brocade Virtual ADX.

Using real server groups you can reduce the size and complexity of load balancing configurations by associating multiple real servers with a single real server group and then binding that group to a virtual server. Brocade Virtual ADX automatically binds all of the real servers associated with the real server group to the bound virtual server.


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Real server groups

Real server group configuration is a three-step process:

• First, you must define the real server group.

• Once defined, you can associate one or more real servers with that real server group. Up to four real servers can be associated with a real server group in a single command.

• You can then bind the real server group to a virtual server.

Although a real server can be associated with one-and-only-one real server group, each real server group can be bound to multiple virtual servers.

Defining a real server group

To define a real server group use the server group-real command.

Virtual ADX(config)#server group-real sg1

Syntax: [no] server group-real real-server-group-name

The real-server-group-name variable identifies the name of the real server group.

The no option enables you to delete a real server group. If you delete a real server group that has been bound to a virtual server, the Brocade Virtual ADX automatically unbinds all of the real servers associated with that real server group. The real servers themselves are not deleted and remain intact in the configuration.

Associating a real server with a real server group

Use the real-server command to associate one or more real servers with a real server group.

Each real server can be associated with one-and-only-one real server group. If you associate a real server with a real server group that is already bound to a virtual server, the Brocade Virtual ADX automatically binds the newly associated real server to the virtual server.

To associate up to four real servers with a real server group, enter a command such as the following:

Virtual ADX(config-rsg-sg1)#real-server rs1 rs2 rs3 rs4

Syntax: [no] real-server real-server-names

The real-server-names variable specifies the real servers associated with a real server group.

The no option enables you to disassociate a real server from a real server group. If you disassociate a real server from a real server group bound to a virtual server, the Brocade Virtual ADX automatically unbinds the real server. Only those real server bindings that were particular to the real server group are removed.


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Binding a real server group to a virtual server

Use the bind group-real command to bind a real server group to a virtual server.

Virtual ADX(config)#server virtual name-or-ip v1

Virtual ADX(config-vs-v1)#bind http group-real sg1 http

A real server group can be bound to multiple virtual servers.

Syntax: [no] bind virtual-server-port group-real real-server-group-name real-server-port

The virtual-server-port variable identifies the virtual server port to be bound to the real server group. The real-server-group-name variable specifies the name of the real server group to which the virtual server is bound. The real-server-port variable specifies the real server port.

NOTE

Do not bind an empty real server group to a virtual server. You must associate at least one real server with a real server group before you bind that real server group with a virtual server otherwise the

Brocade Virtual ADX issues an error.

Showing real server groups

Use the show server group-real command to view real server groups.

To view the real servers or virtual servers bound to a real server group, enter commands such as the following:

Virtual ADX(config)#show server group-real sg1

Real server group: sg1 rs2 rs3 rs4 rs5

Syntax: show server group-real real-server-group-name

The real-server-group-name variable identifies the name of the real server group.


Disabling VIPs

You can globally or individually disable VIPs.

To globally disable all virtual servers, enter the following command.

Virtual ADX(config)#server disable-vip

Use the no server disable-vip command to globally re-enable virtual servers after disabling them.

Syntax: [no] server disable-vip

To disable an individual virtual server, enter commands such as the following.

Virtual ADX(config)#server virtual-name-or-ip www.foo.com

Virtual ADX(config-vs-www.foo.com)#disable

Use the no disable command to re-enable a virtual server.

Syntax: [no] disable


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Disabling a real server

Under the real server config level, you can disable a real server. Disabling a real server also disables all the existing real server ports. The real server state will become “disabled”, and no new connections will be assigned to a disabled real server. However, all the existing connections will remain. No health check will be done for a disabled real server.

To disable a real server, enter commands such as the following.


Virtual ADX(config-rs-rs1)#disable

Syntax: [no] disable

Disabling or re-enabling an application port

Application ports are enabled by default. To disable an application port on a virtual server, enter commands such as the following.

Virtual ADX(config)#server virtual-name-or-ip Zoot_Allures 10.2.3.4

Virtual ADX(config-vs-Zoot_Allures)#port http disable

Syntax: [no] port tcp/udp-port disable

To re-enable a port, enter commands such as the following.

Virtual ADX(config)#server virtual-name-or-ip Zoot_Allures 10.2.3.4

Virtual ADX(config-vs-Zoot_Allures)#no port http disable

Globally disabling real and virtual ports

You can globally disable a Layer 4 port on the Brocade Virtual ADX. The port can be disabled for all real servers, all virtual servers or all real and virtual servers. After you disable a port globally, you can enable the port on individual real or virtual servers as necessary. By default, all real and virtual ports are enabled.

When the Brocade Virtual ADX is booted, if the command to globally disable a real or virtual port exists in the startup-config file, the specified port is disabled at startup. When a real or virtual port is created, and the port has been disabled globally, the real or virtual port is disabled as well. You must enable the port explicitly.

To disable all real HTTP ports, enter commands such as the following.


Virtual ADX(config-port-http)#disable real


To disable all virtual HTTP ports, enter commands such as the following.


Virtual ADX(config-port-http)#disable virtual


To disable all real and virtual HTTP ports, enter commands such as the following.


Virtual ADX(config-port-http)#disable


Syntax: disable [real | virtual]


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Deleting a VIP

It is critical that you follow the steps below before deleting a VIP that is in production or is handling live traffic.

1. Disable the real server ports that are associated with this virtual server port.

Syntax: [no] server real real-server-name

Syntax: [no] port port disable

2. Keep checking the current connection count against the real server until the connection count falls to zero.

Syntax: show server real real-server-name

3. If the current connection value does not drop to zero after some time has passed, then unbind the real server port from under the VIP.

Syntax: no bind virtual-port real-server-name real-server-port

4. Double check to make sure that real server is unbound from the virtual server.

Syntax: show server bind

If the real server is not unbound properly, then check the connection count under the BP console and try clearing the server sessions.


Virtual ADX1/1#show server real rs1

Virtual ADX1/1#rconsole-exit







Syntax: rconsole slot# BP#

Syntax: show server real real-server-name

Syntax: rconsole-exit

If there are existing connections or the port is still in AWU or AWM state, then clear the server sessions using following command.

Syntax: clear server all-session real-server-name real-port

5. After the connection count drops to zero or the unbinding is successful, delete the VIP.

Syntax: no server virtual virtual-server-name

6. If real servers are not required, then delete those also.

Syntax: no server real real-server-name

If any current connection or current session cannot be disabled and the port is in "AWU" or "AWM", then issue a clear server all-session command.


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Enabling force-delete

SLB allows the graceful shutdown of servers and services. By default, when a service is disabled or deleted, the Brocade Virtual ADX does not send new connections to the real servers for that service. However, the Brocade Virtual ADX does allow existing connections to complete normally, however long that takes.

You can force the existing SLB connections to be terminated within two minutes, by using the server force-delete command.

If you disable or delete a service, do not enter an additional command to reverse the command you used to disable or delete the service, while the server is in graceful shutdown.

NOTE

Refer to

“Real server shutdown” on page 83 for important information about shutting down services

or servers.

Suppose you have unbound the Telnet service on real server 15, but you do not want to wait until the service comes down naturally. You can force server load-balancing connections to be terminated by entering the following command.

Virtual ADX(config)#server force-delete

Syntax: server force-delete

To display active sessions for a specific server, enter show server real server number and a display as seen below will appear. Notice that the display below shows the Telnet connection on server 15 as awaiting unbinding. Without server force-delete, this feature will stay in this state until the session ends naturally.

Because the binding is awaiting deletion, it will also still be seen as an active binding, if you enter the show server bind command, such as the following.

Virtual ADX(config-vs-building)#show server bind

Virtual Server Name: building, IP: 10.95.5.130

http -------> s21: 10.95.18.21, http

s15: 10.95.18.15, http

s50: 10.95.18.50, http

ftp -------> s50: 10.95.18.50, ftp

s21: 10.95.18.21, ftp

s15: 10.95.18.15, ftp

telnet -------> s15: 10.95.18.15, telnet

s21: 10.95.18.21, telnet

s50: 10.95.18.50, telnet

After force delete is enabled, the unbinding will occur within two minutes.

NOTE

The binding for the real server will also be eliminated from the show server bind display.


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Real server shutdown

The force shutdown feature (sometimes called the force delete feature) allows you to force termination of existing SLB connections. This feature assumes that you already have shut down a

TCP/UDP service on the real server, or you have shut down the real server itself.

There are several methods for shutting down a service or server. Each method has consequences, so choose the method that works best in your situation. The methods are as follows:

• Edit the real server configuration on the Brocade Virtual ADX to disable the TCP/UDP ports on the server. For example, to disable port 80 (HTTP), you can use the port http disable command at the real server level of the CLI. If you use this method, you do not need to re-define the real server to add the server back to SLB. However, you do need to re-enable the disabled TCP/UDP ports.

• Delete the real server from the Brocade Virtual ADX. This option immediately prevents new connections. To safely delete the real server from the Brocade Virtual ADX, we recommend the following procedure.

1. Under the real server, disable the application ports.

2. Check to ensure the current connections and session comes down to zero (in show server real output).

3. Under VIP, unbind the real server.

4. Delete the real server.

The Brocade Virtual ADX allows existing connections to end normally or, if you have enabled the force shutdown option, the Brocade Virtual ADX ends all connections within two minutes. If you use this method and later want to re-add the real server to the Brocade Virtual ADX, you must redefine the real server, then rebind the real server to the appropriate VIP.

• Shut down the real server itself, rather than change definitions on the Brocade Virtual ADX.

When the real server stops responding to health checks, the Brocade Virtual ADX removes the server from the SLB. This option is simple because it does not require any configuration changes on the Brocade Virtual ADX. However, this option immediately disconnects all users, whereas the above options allow the server or service to gracefully shut down (unless you use the force shutdown option).

Port holddown timer

When a real server port fails, a Brocade Virtual ADX stops sending any new connections to the port.

Configuring the server force-delete command ensures that existing sessions are terminated within two minutes. If a real server port fails and recovers before the force-delete operation has completed, stale sessions can potentially cause problems for clients seeking access to the real servers.

Enabling the port holddown timer disallows a failed port from being marked active until all idle sessions have timed out. Thus, when a real port fails and recovers before a configurable timeout

(default 2 minutes) has elapsed the port is not allowed to move to the active state and is held in a special helddown state. This is a pseudo-state while the port transitions from active to failed and then to testing. If the subsequent health check is successful, the port is marked as active.

If all the ports bound to a VIP are in the helddown state, the VIP would still be in the inactive state.

The behavior of VIP health does not change. Where VIP health is concerned, a real port in the helddown state is equivalent to a real port in the failed state.


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Table 9

describes the behavior of the Brocade Virtual ADX for a specified action when it is configured with the server force-delete command, with a port hold-down timer configured and in a normal scenario without either configured.

TABLE 9

Action

Behavior with server force-delete command

Normal Scenario With Force-Delete

Delete Real Server

Unbind Port

Disable Real Server

Port

Real Port Fails

Sessions deleted within 2 minutes.



Existing sessions continue to exist through their lifetime.

Existing sessions continue to exist through their lifetime.




With Port Hold-down

If real server is re-added, it is treated as a new server addition and port isn’t held down.

If re-bound, the port is not held down.

If enabled quickly (within the timeout) the port is held down.

If the port comes up quickly, the port is held down.

Behavior with flapping ports

If a port keeps flapping within the configured port holddown timeout period, the port is held down until the port stops flapping for the configured timeout. In practice this means that the port must be available for a time interval greater than the configured timeout period for it to come back up.

NOTE

If a port that was disabled when the holddown timer is started is enabled within the timeout period, the port is held down until the timeout period has passed.

The port hold down timer can be configured globally, per real server port and per port-profile.

Changing the default port holddown timer value

The default holddown timeout is 2 minutes. The following command allows you to configure this global timeout value or reset the timeout to the default.

Virtual ADX(config)#server port-holddown-timeout 240

Syntax: [no] server port-holddown-timeout timeout-value

The timeout-value variable specifies the length of the port holddown timer in seconds. Acceptable values are 1 second to 86400 seconds (1 day). The default value is 120 seconds (2 minutes).

The value set by this command applies to all port holddown configurations.

Enabling the port holddown timer globally

You can configure the port holddown timer globally to enable port hold down for all ports on all real servers. This setting overrides any configurations for individual ports.

Virtual ADX(config)#server port-holddown

Syntax: [no] server port-holddown


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Enabling the port hold down timer for an individual real server port

You can configure the port hold down timer to enable port holddown for an individual port within a real server configuration.


Virtual ADX(config-real-rs1)#port http holddown

Syntax: [no] port port-type holddown

The port-type variable specifies the port that you want to apply the holddown timer to.

Enabling the port holddown timer for a port profile

You can configure the port hold down timer to enable port holddown for all ports within a server port profile.

Virtual ADX(config)#server port http

Virtual ADX(config-port-http)#holddown

Syntax: [no] holddown

Displaying port holddown

The show server real and show server real detail commands provide information about the current state and duration of port holddown.

In the following example, the show server real command displays the state of the “http” port as

“HLD”.

Virtual ADX(config)#show server real rs1

Real Servers Info

========================


UNK:unknown, UNB:unbind, AWU:await-unbind, AWD:await-delete,

HLD:held-down

Name: rs1 State: Active Cost: 0 IP:192.168.3.1: 1

Mac: 000c.29b6.64de Weight: 1/1 MaxConn: n/a

SrcNAT: cfg, op DstNAT: not-cfg, not-op Serv-Rsts: 0 tcp conn rate:udp conn rate = 0:0, max tcp conn rate:max udp conn rate = 0:0

BP max local conn configured No: 0 0 0 0 0 0

BP max conn percentage configured No: 0 0 0 0 0 0

Use local conn : No

Port St Ms CurConn TotConn Rx-pkts Tx-pkts Rx-octet Tx-octet Reas

---- -- -- ------- ------- ------- ------- -------- -------- ---default UNB 0 0 0 0 0 0 0 0 http HLD 0 0 0 0 0 0 0 0


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Hash-based SLB with server persistence

The time remaining for the holddown state is displayed by the show server real detail command as shown in the following.

Virtual ADX(config)#show server real rs1 det http HLD 0 0 0 0 0 0 0 0

max_conn = 10 fail time = 0, Vir IP 192.168.1.2

tcp conn rate:udp conn rate = 0:0, max tcp conn rate:max udp conn rate =

0:0



Use local conn : No

resp_time = 7

Keepalive(G/L:Off/On):On

Status Code(s): default (200-299, 401)

HTTP URL: "HEAD /"

tcp-age: 30

Hold-down time remaining: 25 second(s) dns ACT 0 0 39 39 45 10151 3972 0


This feature provides a persistent hashing mechanism for virtual server ports, which evenly distributes hash assignments and enables a client to always be redirected to the same real server.

Command support is also provided to help you manage the introduction of a new server.

This feature enables a client to always be redirected to the same real server. The client will be directed to a new real server only if the assigned real server fails.

By default, SLB uses stateful load balancing for Virtual IP addresses (VIPs). In stateful load balancing, the Brocade Virtual ADX creates session table entries for the connections between the client and the destination (the real server). If multiple real servers are bound to a VIP, then requests from the same client can be serviced by different real servers over a period of time.

However, for transaction-oriented systems, a client might need to be serviced by the same real server each time the client makes a request, regardless of the length of time between each request made.

Using the sticky feature, the current maximum persistence possible for Stateful SLB is 20 hours.

This setting might not be sufficient for systems that always need the client to be directed to the same real server, unless an event such as real server failure necessitates reassignment of the client to a different server.

Persistent hash table

Each virtual server port maintains a persistent hash table consisting of 256 entries. When the

Brocade Virtual ADX boots up, all the hash entries in the table are empty (no real server assignments to any of the entries). When a client makes a request to the VIP, the Brocade Virtual

ADX calculates a hash value based on the client IP. The hash will be a value between 0 and 255 and will map to one of the entries in the persistent hash table. The Brocade Virtual ADX then retrieves the persistent hash table entry for the calculated hash value. If there is no real server allocated for the table entry, the Brocade Virtual ADX selects a real server for that table entry using the configured SLB predictor. The system will then assign the real server to the table entry, and the client request will be serviced by the real server.


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If the client makes another request to the VIP, for example after two days, then the Brocade Virtual

ADX will again calculate the hash based on the client IP and retrieve the persistent hash table entry. Because a real server has already been allocated to the persistent hash table entry, the

Brocade Virtual ADX will use this real server to service the client request. As an effect, the client will always be directed to the same real server.

Clear vs reassign mechanisms

There are two configurable mechanisms to handle the introduction of a new server:

• clear-on-change — Whenever a new server comes up, the entire persistent hash table is cleared and assignments are started afresh. For more information, refer to

“Enabling the clear-on-change mechanism” on page 87.

• reassign-on-change — The default. Whenever a new server comes up, the Brocade Virtual ADX calculates the number of hash entries allocated to each existing server. The Brocade Virtual

ADX then reassigns some of these entries to the new server. For more information, refer to

“Enabling the reassign-on-change mechanism” on page 88.

Enabling persistent hashing

To enable the persistent hashing (phash) mechanism for a virtual server port, enter commands such as the following.


Virtual ADX(config-vs-vs1)#port http persist-hash

The reassign-on-change function is selected by default.

Syntax: [no] port port persist-hash [clear-on-change | reassign-on-change]

When persistent hashing is configured for a VIP, the round robin predictor for the VIP is automatically enabled. This default is used to evenly distribute hash assignments. After you enter the port port persist-hash command, the predictor round-robin command automatically appears under the virtual server in the configuration file.

NOTE

SSL is a special case where sticky automatically gets turned on. If persistent hashing must be configured for port SSL, you need to explicitly turn off sticky on the SSL port using the no port ssl sticky command and then enable persistent hashing for this port.

Enabling the clear-on-change mechanism

To enable the clear-on-change mechanism, enter commands such as the following.


Virtual ADX(config-vs-vs1)#port http persist-hash clear-on-change

Virtual ADX(config-vs-vs1)#end

When the clear-on-change command is set for persistent hashing, the entire persistent hash table is cleared whenever a new server comes up. For example, is shown in the following figure.


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Figure 14

shows the persistent hash table for a virtual server port before the rs3 comes up.

FIGURE 14 Hash table before rs3 comes up

Persistent Hash table virtual server vs1 port http

Hash 0

Hash 1

Hash 2

Hash 3

Hash 4

Hash 5

Hash 6

..............

Hash 255 none

Assume the administrator now binds port HTTP of a new real server rs3 to port HTTP of virtual server vs1. When real server rs3 comes up, the entire persistent hash table is cleared.

Figure 15

shows the persistent hash table for a virtual server port after the rs3 comes up.

FIGURE 15 Hash table after rs3 comes up none rs2 rs2 rs1 rs1 rs2 rs1 virtual server vs1 port http

Hash 0

Hash 1

Hash 2

Hash 3

Hash 4

Hash 5

Hash 6

..............

Hash 255

Persistent Hash table none none none none none none none none

Enabling the reassign-on-change mechanism

To enable the reassign-on-change mechanism, enter commands such as the following.


Virtual ADX(config-vs-vs1#port http persist-hash reassign-on-change

When reassign-on-change is enabled (the default), the Brocade Virtual ADX reassigns some of the existing hash table entries on the introduction of a new server.


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Configuring the reassign threshold and duration

There are two configurable global parameters related to the reassign mechanism:

• Reassign threshold — When the number of empty hash entries (buckets) in the persistent hash table falls to or below this threshold (less than or equal to), the Brocade Virtual ADX reassigns some of the persistent hash entries on introduction of a new real server. By default, the

Brocade Virtual ADX reassigns persistent hash entries to the new real server only if there are no empty persistent hash entries (for example, the default persist hash reassign threshold is 0 percent).

To specify the threshold, enter a command such as the following.

Virtual ADX(config)#server persist-hash-threshold 5

Syntax: [no] server persist-hash-threshold percent-value

The percent-value variable can be any value from 0 through 99.

With the reassign mechanism, if multiple servers come up simultaneously and need reassignment because the number of empty hash table entries is below the reassign threshold, then the Brocade Virtual ADX will clear the persistent hashing table.

• Reassign duration — If the number of empty persistent hash entries is below the reassign threshold, the Brocade Virtual ADX reassigns some of the persistent hash entries over a period of time to the new real server. This duration of time is known as the persist hash reassign duration.

To specify the reassign duration, enter a command such as the following.

Virtual ADX(config)#server persist-hash-reassign-duration 5

This global command is applied to all configured VIP ports that are persist-hash enabled. The

Brocade Virtual ADX will complete the reassignment within 2 minutes by default.

Syntax: [no] server persist-hash-reassign-duration value

The value variable can be a time duration from 2 to 30 minutes.

Reassignment sequence and example

The sequence is performed as follows.

1. When a new server is introduced, the Brocade Virtual ADX calculates how many of the hash table entries in the persistent hash table are empty. If the number is greater than the persist-hash-reassign-threshold, the Brocade Virtual ADX does no reassignment.

If the number of empty hash table entries is less than or equal to the persist hash reassign threshold, the Brocade Virtual ADX proceeds with the reassignment. The system first calculates the total number of active real servers, which includes the new real server.

2. The system calculates the entries per server as follows.

X = entries per server = total assigned hash table entries/number of active real servers

3. The Brocade Virtual ADX attempts to reassign X persistent hash entries to the new real server over the duration specified by the persist-hash-reassign-duration.


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The Brocade Virtual ADX will stop reassigning persistent hash entries to the new real server when either of the following occurs:

• The system has finished reassigning X persistent hash entries to the new real server (occurs in the amount of time specified by the persist-hash-reassign-duration).

• The number of persistent hash entries assigned to the new real server is equal to the lowest number of persistent hash entries assigned to any of the existing real servers, whichever happens earlier.

Consider the following reassignment example.

Figure 16 shows the hash table before

reassignment.

FIGURE 16 Hash table before reassignment virtual server vs1 port http

Persistent Hash table

Hash 0

Hash 1

..............

Hash 47

Hash 48

Hash 49

Hash 50

Hash 51

Hash 52

Hash 53

Hash 54

Hash 55

Hash 56

..............

Hash 255 none none none rs1 rs1 rs1 rs1 rs1 rs1 rs1 rs1 rs2 rs2

Persistent hash entries have been assigned as follows. Entries 47 to 54 have been assigned to real server rs1. Entries 55 and 56 have been assigned to rs2. All other entries are empty (no real server has been assigned to them).

In this example, the administrator configures a reassign-threshold of 99 percent. That is, whenever the number of empty hash entries falls below 99 percent, the Brocade Virtual ADX will reassign the persistent hash table entries whenever a new real server comes up. The reassign-duration is the default value (2 minutes).

Next, the administrator binds port HTTP of a new real server rs3 to port HTTP of virtual server vs1.

When real server rs3 comes up, the Brocade Virtual ADX calculates the number of active real server ports. In this example, the number is 3 (rs1, rs2 and rs3). The system then calculates the number of empty hash table entries. In this example, the number is 246. Because less than 99 percent of the hash table entries are empty, the Brocade Virtual ADX now attempts to reassign some of the persistent hash entries to the new real server rs3.

The Brocade Virtual ADX then calculates entries per server X as follows.

X = total assigned hash table entries/number of active real servers = 10/3 = 3


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The Brocade Virtual ADX now attempts to reassign 3 persistent hash entries to the new real server over 2 minutes. The system will stop after it has reassigned 2 entries of real server rs1 to new real server rs3. The reason is that when rs3 is assigned 2 persistent hash entries, the value is equal to the number of entries assigned to existing real server rs2.

Figure 17 shows the persistent hash table after the reassignment.

FIGURE 17 Hash table after reassignment virtual server vs1 port http


Hash 0

Hash 1

..............

Hash 47

Hash 48

Hash 49

Hash 50

Hash 51

Hash 52

Hash 53

Hash 54

Hash 55

Hash 56

..............

Hash 255 none none none rs3 rs3 rs1 rs1 rs1 rs1 rs1 rs1 rs2 rs2

Keeping the persistent hash table unchanged

To configure the Brocade Virtual ADX not to clear the persistent hashing table when multiple servers come up simultaneously and need reassignment, enter commands such as the following.

SLB-Virtual ADX(config)#server virtual-name-or-ip vs1

SLB-Virtual ADX(config-vs-vs1)#port http no-auto-clear-persist-hash-buckets

If this command is configured and multiple servers need reassignment simultaneously, then the

Brocade Virtual ADX will leave the persistent hash table unchanged.

Syntax: port port no-auto-clear-persist-hash-buckets


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Real server failure

If a real server fails, the Brocade Virtual ADX will remove all assignments of the real server from all persistent hash table entries in the persistent hash table.

For example, consider a virtual server vs1 whose port HTTP is bound to port HTTP of real server rs1

and rs2. Figure 18 shows the persistent hash table for vs1 for port HTTP before server failure.

FIGURE 18 Hash table before server failure virtual server vs1 port http


Hash 0

Hash 1

Hash 2

..............

Hash 255 rs1 rs2 rs1 none

Real server rs1 has been assigned to persistent hash table entries corresponding to hash value 0 and hash value 2. Real server rs2 has been assigned to the entry corresponding to hash value 1.

Now assume all other hash table entries have not been assigned to any real servers.

If port HTTP of real server rs1 fails, then the Brocade Virtual ADX will clear assignment of rs1 to the persistent hash entries in the above table.

Figure 19

shows the persistent hash table for vs1 for port HTTP after server failure.

FIGURE 19 Hash table after server failure virtual server vs1 port http


Hash 0

Hash 1

Hash 2

..............

Hash 255 none rs2 none none

The Brocade Virtual ADX does not immediately assign a new server to the cleared hash table entries. Instead, the Brocade Virtual ADX will select and assign a real server for these entries using the SLB predictor the next time a client hashes to these hash table entries.


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In the previous example, assume a client now makes an HTTP request for virtual server vs1.

Assume also the client’s IP address hashes to a value of 2. The Brocade Virtual ADX checks the hash table entry corresponding to hash value 2 in the above persistent hash table. Because no real server is associated with the hash entry, the Brocade Virtual ADX selects a new real server, such as rs2, using the SLB predictor and then assigns the server to the hash table entry. This and

subsequent requests from the client will then be serviced by rs2. Figure 20

shows the new real server rs2 to service request to the client.

FIGURE 20 Using rs2 to service requests virtual server vs1 port http


Hash 0

Hash 1

Hash 2

..............

Hash 255 none rs2 rs2 none

Displaying persistent hash table entry and statistics

To display the persistent hash table entry and statistics for a virtual server, use rconsole to get into the BP and enter the show server persist-hash-buckets command.


Virtual ADX1/1#show server persist-hash-buckets http-vs

Virtual port Persist Hash Buckets:

Virtual Server <http-vs> Port <80>:

Bucket: Server Hit Bucket: Server Hit

45: http-rs1 1

Virtual Server <http-vs> Port <53>:

Bucket: Server Hit Bucket: Server Hit

45: dns-ns 2

Syntax: show server persist-hash-buckets virtual-server-name

If you do not specify a virtual server name, all the persistent hash tables for all virtual server ports

for all virtual servers will be displayed. Table 10 displays the output field description of show server

persist-hash-buckets command.

TABLE 10 Output field descriptions of show server persist-hash-buckets command

Field Description

Virtual server

Port

Bucket

Server

Hit

Name of the virtual server.

Virtual server port.

Hash value for hash table entry.

Real server assigned to the hash table entry.

Number of times the client IP has hashed to this entry and been serviced by the associated real server. It is possible for multiple clients to hash to the same hash entry (bucket).


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Clearing the hit count for the persistent hash table

To clear the hit count for the persistent hash table for a virtual server port, enter commands such as the following.

Virtual ADX(config)#server virtual-name-or-ip http-vs

Virtual ADX(config-vs-http-vs)#port http clear-persist-hash-statistics

Virtual ADX(config-vs-http-vs)#end

Syntax: port port clear-persist-hash-statistics

Clearing the persistent hash table

To clear the persistent hash table (all assignments and hit counts) for a virtual server port, enter commands such as the following.

Virtual ADX(config)#server virtual-name-or-ip http-vs

Virtual ADX(config-vs-http-vs)#port http clear-persist-hash-buckets

Virtual ADX(config-vs-http-vs)#end

Syntax: port port clear-persist-hash-buckets

Reassigning a persistent hash table entry

To manually reassign a persistent hash table entry to a real server for a specified client IP, enter a command such as the following.

Virtual ADX#show server manual-persist-assign-hash 10.1.1.33 http-vs 80 http-rs1

80

Hash bucket for Client IP 10.1.1.33 = 36

Server http-rs1 allocation to bucket 36 of specified virtual server for port 80 completed!

Syntax: show server manual-persist-assign-hash client-ip virtual-server-name virtual-port real-server-name real-port

If you manually assign a real server for a hash table entry for which another real server is currently assigned, the new real server will replace the old real server for the hash entry as follows.

Virtual ADX#show server manual-persist-assign-hash 10.1.1.33 http-vs 80 http-rs2

80

Hash bucket for Client IP 10.1.1.33 = 36

Replacing current server http-rs1 allocated for hash 36 with server http-rs2

Server http-rs2 allocation to bucket 36 of specified virtual server for port 80 completed!


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Displaying hash bucket changes

You can display information about hash bucket changes on the Brocade Virtual ADX, through use of the show server proxy keep-alive command. A truncated display is shown with the hash bucket information.

Virtual ADX#show server proxy keep-alive

Keep-alive connection statistics:

...

Hash Bucket Change:

Current serv is down =

Lower BP wins =

...

Virtual ADX#

1

0

Serv exceed max-con =

Syntax: show server proxy keep-alive

Table 11 displays the output field description of show server proxy keep-alive command.

TABLE 11 Output field descriptions for hash buckets of show server proxy keep-alive command

Field Description

Current serv is down

Serv exceed max-conn

Lower BP wins

The current server is down.

Not applicable

The hash table is synchronized to all BPs. Where another BP assigns the bucket to a different server, the lower BP wins.

0

SLB spoofing configuration and support

Spoofing is the Brocade Virtual ADX application switch's ability to redirect reverse SLB traffic to the interface from where the actual connection came through, regardless of any other route configured.

When spoofing is enabled for a port on a virtual server, the Brocade Virtual ADX marks the input interface of the connection. Later any response traffic for the session will be forwarded using this information regardless of any other route (like next-hop route, policy based route, default route) configured.

Configuration example:


Virtual ADX(config-vs-vip1)#port http

Virtual ADX(config-vs-vip1)#port http spoofing

Syntax: [no] port port spoofing

SLB spoofing is supported for all TCP traffic except for complex protocol ports (for example FTP,

MMS, RTSP and TFTP).

SLB spoofing is supported for UDP with the following limitations.

• UDP spoofing will not work if dns-udp-count-connection is configured.

• It is not supported for IMCP response traffic originated from the VIP.


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Policy-based SLB

Policy-based SLB

Policy-based server load balancing (PBSLB) is the Brocade Virtual ADX ability to direct requests to a server group based on the source IP address of the request.

When policy-based SLB is enabled for a port on a virtual server, the Brocade Virtual ADX examines the source IP address of each new connection sent to the VIP on the port. The Brocade Virtual ADX looks up the source IP address of the request in an internal policy list. The policy list is a table that associates IP addresses with real server groups. If an entry for the IP address is found in the policy list, then the Brocade Virtual ADX forwards the request to the associated real server group. If no entry for the IP address is found, the Brocade Virtual ADX directs the request to a server group specified as the "default" server group.

Figure 21

shows a sample policy-based SLB configuration.

FIGURE 21 Policy-based SLB configuration

96

The policy list contains three entries: one associating IP address 10.10.10.10 with Real Server

Group 1, another associating network address 20.20.0.0/16 with Real Server Group 2. In addition,

Real Server Group 3 is specified as the default server group.

In this example, policy-based SLB works as follows:

• When a request from address 10.10.10.10 is received on the VIP, the Brocade Virtual ADX forwards the request to one of the load-balanced servers in Real Server Group 1.

• When a request from network 20.20.0.0/16 is received, it is forwarded to the real server in group 2.


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• When a request from a different address is received, because it does not have an entry in the policy list, it is forwarded to one of the load-balanced real servers in the default server group, which is specified as group 3.

NOTES:

• Policy-based SLB is enabled for individual ports on virtual servers.

• Because policy-based SLB is enabled on a per-VIP basis, some VIPs configured on the

Brocade Virtual ADX can have policy-based SLB enabled, while others do not.

• Policy-based SLB can exist on a standalone device or in a Hot Standby high-availability configuration.

• Policy-based SLB cannot coexist on the same VIP with Layer 7 switching features, including URL switching and cookie switching.

Configuring a policy list

A policy list can be created in two ways depending on the number of policies being defined:

• If the number of policies is small, you can create the policy list file using the CLI. Refer to

“Creating the policy list using the CLI.”

• If the number of policies is large, you can download the policy list file from a TFTP server. Refer to

“Creating the policy list file to dynamically download from a TFTP server.”

Creating the policy list using the CLI

The following command can be used to add policies.

Virtual ADX(config)#server pbslb add 10.10.10.10 1

Syntax: server pbslb add ipv4-addr { prefix | netmask [ server-group-id ]

The ipv4-addr variable can be a complete host address, or a network address followed by IPv4 mask bits. You must specify either a prefix or a netmask.

The server-group-id variable is alphanumeric and refers to one of the real server groups configured on the Brocade Virtual ADX.

For the example shown in

“Policy-based SLB configuration” on page 96, the policies can be added

as shown in the following.

Virtual ADX(config)#server pbslb add 10.10.10.10 1

Virtual ADX(config)#server pbslb add 20.20.0.0/16 2

Creating the policy list file to dynamically download from a TFTP server

To dynamically download a policy list file from a TFTP server, it must be a flat ASCII text file that consists of one or more policy-based SLB entries configured in the following format.

ip-addr [ network-mask ] [ server-group-id ]

The ip-addr variable can be a complete host address, or a network address followed by IP mask bits.



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For the example shown in

“Policy-based SLB configuration” on page 96, the policies would be

defined as shown in the following.

10.10.10.10 1

20.20.0.0/16 2

The policy list file created in the format defined above can be transferred to the Brocade Virtual

ADX from a TFTP server. A single download file should contain all IPv4 entries. These entries can be in any order.

NOTE

Downloading a new file overwrites the existing policy list file on a Brocade Virtual ADX. Consequently any entries that are not in the most recent download will be lost.

Dynamically downloading a policy list using TFTP

When a policy list is created, as described in “Creating the policy list file to dynamically download from a TFTP server”

, the following command can be used to download the file from a TFTP server.

Virtual ADX(config)#server pbslb tftp 192.168.9.210 policy-list.txt 5

When you enter this command, the downloaded policy list file immediately replaces the entries in the Brocade Virtual ADX’s policy-based SLB configuration.

Syntax: server pbslb tftp tftp-server-ip-addr filename retry-count

The tftp-server-ip-addr variable specifies the IP address of the TFTP server.

The filename variable specifies the name of the policy list file.

The retry-count variable specifies the number of times that the Brocade Virtual ADX retries the download if the first attempt is not successful.

Redirecting traffic to the default group during download

The Brocade Virtual ADX supports seamless download (or no blocking of VIP traffic while a policy list is being downloaded) only when the number of PBSLB entries do not exceed 1,000,000 IPv4 entries. A Brocade Virtual ADX maintains two separate tables in memory: one for the existing list and one for the new list that is being downloaded. After the new list is completely downloaded, it is swapped with the existing list. This method allows for the new policy list to take effect immediately without affecting the VIP traffic during the download.

NOTE

This redirect method only applies when the maximum number of PBSLB entries has not been increased to 5,000,000 for IPv4 through the use of the server pbslb max-entries command.

For policy list files that contain more than 1,000,000 entries, all VIP traffic will be blocked during the download and will resume only after the policy list file is completely downloaded. To be able to send VIP traffic to the default server group instead of blocking it during download, enable the server pbslb send-to-default-group-during-download feature.

There are three steps to turn on this feature.

1. Create a PBSLB default group-ID.

2. Assign real server ports to the default group.

3. Enable send-to-default-group-during-download.


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Creating a PBSLB default group

To create a PBSLB default group, enter a command such as the following.

Virtual ADX(config)#server pbslb default-group-id ipv4 4

Syntax: [no] server pbslb default-group-id ipv4 group-id

Assigning real server ports to default group

A default group can contain one or more real servers. If there is more than one real server in a default group, requests are load balanced across all the servers in the group. To assign real servers to the default group, enter commands such as the following.

Virtual ADX(config)#server real-name rs1 10.95.7.14

Virtual ADX(config-rs-rs1)#port http group-id 4 4


Enabling pbslb send-to-default-group-during-download

To enable send-to-default-group-during-download, enter a command such as the following.

Virtual ADX(config)#server pbslb send-to-default-group-during-download

Syntax: [no] server pbslb send-to-default-group-during-download

NOTE

You configure this command only if you have increased the maximum number of PBSLB entries over the default number.

Specifying the maximum number of entries

You can optionally specify the maximum number of entries allowed for a policy-based SLB configuration. The minimum, maximum and default values are determined by the license that is active on your system. For actual values associated with your license, refer to the Brocade Virtual

ADX Licensing Guide .

For example, to specify 40,000 as the maximum number of IPv4 entries for policy-based SLB, enter the following command.

Virtual ADX(config)#server pbslb max-entries ipv4 40000

Syntax: server pbslb max-entries ipv4 max-number

The max-number variable specifies the maximum number of PBSLB entries you want to configure.

The maximum number of IPv4 entries that the Brocade Virtual ADX supports is determined by the license that is active on your system. For actual values associated with your license, refer to the

Brocade Virtual ADX Licensing Guide .

After you enter this command and save the configuration, you must reload the software for the new maximum limit to take effect.

Deleting an entry from the policy list

To delete an entry from the policy list, enter the following command.

Virtual ADX(config)#server pbslb delete 10.10.10.1/24 4

Syntax: server pbslb delete ipv4-addr { netmask | prefix [ server-group-id ]}


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Policy-based SLB

The ipv4-addr variable specifies the IPv4 entry that you want to delete from the policy list. You must specify either a prefix or a netmask.


Deleting an entire PBSLB list

To delete the entire PBSLB list, enter a command such as the following.

NOTE

This command will delete all the entries in the PBSLB list. You can enter the show pbslb all 0 command to first display the contents of the list before deleting the entire list.

Virtual ADX(config)#server pbslb delete all ipv4

The whole IPv4 table of PBSLB has been deleted.

Syntax: server pbslb delete all ipv4

Copying a policy list to a file on TFTP server

To copy the currently loaded policy list from the Brocade Virtual ADX to a file on a TFTP server, enter a command such as the following.

Virtual ADX#copy pbslb-running-config tftp 192.168.9.210 policy-list.txt

Syntax: copy pbslb-running-config tftp tftp-server-ip-addr filename

The tftp-server-ip-addr variable is the IP address of the TFTP server.

The filename is the name the policy list file will be saved as.

Specifying a default server group

When a new connection is sent to a VIP where policy-based SLB is enabled, if no entry for the source IP address is found in the policy list, the Brocade Virtual ADX directs the request to a server group specified as the "default" server group.

To specify a server group as the default server group, enter a command such as the following.

Virtual ADX(config)#server pbslb default-group-id ipv4 3

Syntax: server pbslb default-group-id ipv4 group-id

The group-id variable is alphanumeric and refers to one of the real server groups configured on the


Assigning real servers to server groups

The policy list associates source IP addresses with real server group IDs. To configure policy-based

SLB, you assign real servers to real server groups.

A real server group can contain one or more real servers. If there is more than one real server in a server group, requests are load balanced across all the servers in the group. To assign real servers to server groups, establish the IP address of each real server and specify the server groups to which it belongs.


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For example, to configure real server rs1 in Figure 21 on page 96, enter commands such as the

following.




Syntax: [no] server real real-server-name ip-addr

Syntax: [no] port port group-id server-group-id-pairs

In this example, the server real command defines a real server called rs1 with an IP address of

10.95.7.1.

The port http group-id command indicates the server groups to which the real server belongs. The server group is expressed as a pair of numbers, indicating a range of real server group IDs. The first number is the lowest-numbered server group ID, and the second is the highest-numbered server group ID. For example, if a real server belongs only to the server group with ID = 1, the last two numbers in the port http group-id command would be 1 1. (Note the space between the two numbers.) If a real server belongs to server groups 1 through 10, the last two numbers in the command would be 1 10. Valid numbers for server group IDs are from 0 through 1023.

To include a real server in groups that are not consecutively numbered, enter up to four server group ID pairs. For example, to include a real server in groups 1–5 and 11–15, enter the following command.

Virtual ADX(config-rs-rs1)#port http group-id 1 5 11 15

You can also specify the server group ID pairs on separate lines; for example.



The configuration for the remaining real servers in Figure 21 on page 96 is shown below. These

commands place real server rs2 in server group ID = 1 (along with real server rs1), real server rs3 in server group ID = 2, and real server rs4 in server group ID = 3.










Enabling PBSLB for a port on a virtual server

To enable policy-based SLB on a VIP for

Figure 21 on page 96, enter commands such as the

following.

Virtual ADX(config)#server virtual-name-or-ip mysite 10.157.22.63

Virtual ADX(config-vs-mysite)#port http

Virtual ADX(config-vs-mysite)#port http sw-l4-pbslb

Virtual ADX(config-vs-mysite)#bind http rs1 http rs2 http rs3 http rs4 http

Syntax: [no] port port sw-l4-pbslb


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Deleting existing PBSLB sessions

By default, when a PBSLB server group configuration changes, the client sessions with that group remain open. For example, if a client has sessions associated with Group A, but Group A’s configuration changes and moves the client sessions to Group B, the sessions with Group A are still open. You can change this behavior by enabling the scan-session-table-after-config-change feature.

With this feature enabled, old connections are deleted and a new connection is set up with a new group whenever a PBSLB server's configuration changes.

To enable this feature, enter the following command.

Virtual ADX(config)#server pbslb scan-session-table-after-config-change

Syntax: [no] server pbslb scan-session-table-after-config-change

Use the no form of the command to disable this feature. The feature is disabled by default.

PBSLB pool failsafe group

The PBSLB pool failsafe group feature allows a Brocade Virtual ADX to direct traffic away from a given server pool to a "default pool" in situations where the servers in the server pool become unavailable.

Overview of PBSLB pool failsafe group

When PBSLB is used to filter traffic based on source IP address, a Brocade Virtual ADX looks up a group id for the client to forward the incoming request to. If all the servers in the group fail, the

Brocade Virtual ADX sends a TCP reset to the client, causing the request to fail. This feature allows you to configure a failsafe group, which will be used to forward traffic, in case the group designated for a client source-ip address fails. The following section outlines the behavior of this feature in two scenarios.

For IP addresses present in the PBSLB list:

• If the group-id is 0 (deny group), the traffic is denied (RST in case of TCP and drop in case of udp).

• If the group-id is not 0, if the servers are healthy, traffic is load balanced among servers as per predictor.

• If all servers of the group are in a failed state, traffic is load balanced among "failsafe" group servers.

• If all of the servers of the "failsafe" group are in a failed state, traffic is denied (RST in case of

TCP and drop in case of UDP).

For IP addresses not present in the PBSLB list:

• If the default-group-id is not configured or is configured as 0 (deny group), traffic is denied.

• If the default-group-id is configured, traffic is load balanced among default-group servers as per predictor.

• If all of the servers of the default-group are in a failed state, the traffic is load balanced among

"failsafe" group servers.

• If all of the servers of the failsafe group are in a failed state, the traffic is denied.


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Command line interface

There are three steps to enable this feature.

1. Create a PBSLB failsafe group ID.

2. Assign real server ports to a failsafe group.

3. Enable PBSLB on a VIP port.

Creating a PBSLB failsafe group

To create a PBSLB failsafe group, enter a command such as the following.

Virtual ADX(config)#server pbslb failsafe-group-id ipv4 2

Syntax: [no] server pbslb failsafe-group-id ipv4 group-id

The group-id variable is alphanumeric and refers to one of the real server groups configured on the


Assigning real server ports to a failsafe group

A failsafe group can contain one or more real servers. If there is more than one real server in a failsafe group, requests are load balanced across all the servers in the group. To assign real servers to the failsafe group, enter commands such as the following.




Enabling PBSLB on a VIP port

To enable PBSLB on a VIP port, enter commands such as the following.

Virtual ADX(config)#server virtual-name-or-ip mysite 10.157.22.63

Virtual ADX(config-vs-mysite)#port http

Virtual ADX(config-vs-mysite)#port http sw-l4-pbslb

Virtual ADX(config-vs-mysite)#bind http rs1 http

Using show commands

To view the number of requests forwarded to the failsafe server group, enter the following command.

Virtual ADX#show pblsb failsafe ipv4

Syntax: show pbslb failsafe ipv4

To clear the PBSLB failsafe counter, enter the following command.

Virtual ADX#clear pbslb failsafe

Syntax: clear pbslb failsafe

Auto Download of PBSLB list

Policy Based Load Balancing (PBSLB) Auto Download allows you to automatically download a list of policies to the Brocade Virtual ADX at a scheduled interval or a specific time of day. This automation precludes the need to write scripts and cron jobs. Using PSLB Auto Download, you can regularly upload an updated PBSLB list to the Brocade Virtual ADX on a pre-determined schedule.


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NOTE

The server pbslb tftp command must be configured before the server pbslb time-of-day or server pbslb download-interval command, so the Brocade Virtual ADX knows which server and file name to use in the download.

NOTE

The PBSLB time-of-day granularity is in minutes, so seconds are ignored in the configuration. For example, if you enter time as 16:35:30, it is taken as 16:35:00.

Configuring PBSLB download interval

To configure the Brocade Virtual ADX to download a PBSLB list at a periodic interval, use commands similar to the following.

Virtual ADX(config)#server pbslb tftp 10.10.1.101 iplist.txt 2

Virtual ADX(config)#server pbslb download-interval 20

Syntax: server pbslb download-interval interval-in-minutes

In this example, the Brocade Virtual ADX downloads the list in iplist.txt from server 10.10.1.101 once every 20 minutes. If it encounters an error, it retries two times.

PBSLB syslog messages

Messages similar to the following appear whenever autodownload PBSLB is executed.

Aug 15 21:23:59:I:PBSLB config file 5mil-2.txt downloaded from TFTP server

172.20.1.6 -->

The preceding line indicates success.

Aug 16 13:30:03:A:FAILED to download PBSLB config file 5mil-2.txt from TFTP server

172.20.1.6 -->

The preceding line indicates failure.

Aug 16 14:20:59:W:RETRY download of PBSLB config file 5mil-2.txt from TFTP server

172.20.1.6 -->

The preceding line indicates a retry.

Displaying PBSLB entries

You can display one or more entries in the currently loaded policy list. To display an individual policy list entry, enter a command such as the following.

Virtual ADX#show pbslb 10.10.1.101

IP address Mask Server Group ID

10.10.1.101

128 11

Syntax: show pbslb ip-address

The ip-address variable specifies the IPv4 address of the entry in the currently loaded policy list that you want to display.

The show pbslb command displays the entry in the policy list that corresponds to the specified IP address. If no entry is found for the specified IP address, no output is displayed.


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To display multiple entries in the policy list, enter a command such as the following.

Virtual ADX#show pbslb all ipv4 10

Max Count: 1000000 Total Count: 2

IP address

10.10.1.101

Mask

128

Server Group ID

11

Syntax: show pbslb all ipv4 index

The show pbslb all command displays 20 entries in the policy list, starting from the point specified with the index variable. In the example, 20 entries in the policy list are displayed, starting from the

100th entry.

Packet trace

When a policy list file is downloaded to the Brocade Virtual ADX, messages to indicate download progress are printed on the console. By default, when a policy list file is downloaded through a

Telnet or SSH session to the Brocade Virtual ADX, these messages do not appear on the Telnet or

SSH session. To monitor the download progress, you need to enable packet trace using the following command.

Virtual ADX#ptrace term debug output is now sent to this terminal

Syntax: ptrace term

Virtual ADX(config)#server pbslb tftp 10.1.1.1

pbslb/pbslb2M.txt 1 Download of pbslb config from TFTP server is initiated.

.SLB-telnet@Virtual ADX(config)#.............................................

...............................Download of pbslb config from TFTP server is done.

TFTP file size = 27718556, Entry count = 1000000, Parse error = 0, Table full error 1000000 Resetting pbslb trie Processing PBSLB entries

.......................................PBSLB processing done

BP sync msg = 200, BP Sync fail = 0

Duplicates = 0, Alloc err = 0, Full err = 0, Unknown err = 0

TABLE 12 Error messages

Message Description

BP sync msg

BP Sync fail

Alloc err

The number of messages that it took for the MP to synch the downloaded PBSLB table to the BP (The download itself is staggered, so it is done in multiple passes).

The number of messages (mentioned above) that failed successful transmission. In the event of a failure, the message is sent again.

If BP sync fails, the MP will try to push down the PBSLB table to the BPs again after

100 ms. This process continues until the BP synch is completely successful. On the

BP, the PBSLB tree is not populated until the download is totally successful.

The number of times the Brocade Virtual ADX was unsuccessful in allocating memory for the PBSLB table. The device tries to allocate the entire table at once, so if there is an error, this counter can only show a value of 1.


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Miscellaneous options

TABLE 12 Error messages (Continued)

Message Description

Full err

Unknown err

The number of times the Brocade Virtual ADX could not add a new PBSLB entry to the table because the PBSLB is already full. This value should indicate the number by which the downloaded pbslb table size exceeds the value that the Brocade Virtual

ADX supports.

When the PBSLB list is downloaded, it is first populated into a flat table that does not have any hierarchy. After populating this table, the MP will construct the DP table to actually store the PBSLB entries for later lookups. Even when the MP synchs the

PBSLB info to the BPs, it is the flat table that is pushed down and not the DP table.

Full error refers to those error cases where new entries cannot be added to the DP table because the tree is already full. Table full error refers to those error cases where no more entries can be added to the flat table because the flat table is filled up.

Is used to catch miscellaneous unexpected errors. For example, if the download buffer of the PBSLB table from MP to BP is corrupted. Another example is when we try to add an entry to the tree and the entry cannot be added due to an unexpected error.


Changing a real server’s IP address

The Brocade Virtual ADX enables you to easily change a real server’s IP address, even when the real server is active. This capability is useful when you want to perform some maintenance on the real server (either the server itself or the server’s configuration on the Brocade Virtual ADX) or when the network topology has changed.

By default, when you change a server’s IP address, the Brocade Virtual ADX performs the change gracefully, as follows:

• Existing connections are allowed to continue on the old IP address until they terminate normally.

• New client requests are sent to the new IP address.

Optionally, you can force all existing connections to be reset instead of waiting for them to terminate normally. When you force the connections to be reset, the Brocade Virtual ADX immediately resets a connection when it receives client data for the connection.

To change a real server’s IP address, enter commands such as the following.


Virtual ADX(config-rs-rs1)#ip-address 10.6.7.8

Syntax: [no] ip-address ip-addr [force-shutdown]

The ip-addr variable specifies the new IP address for the real server.

The force-shutdown parameter immediately resets a client’s connection to the IP address when the

Brocade Virtual ADX receives TCP data from the client. By default, the Brocade Virtual ADX allows existing connections to terminate normally following the address change.


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Adding a description

You can add a description to a real server or virtual server. The description appears in the output of show commands and in the running-config and startup-config files.

To add a description, enter commands such as the following.

Virtual ADX(config)#server real RS20 10.2.3.4

Virtual ADX(config-rs-RS20)#description "Real Server #20"

Syntax: [no] description “ text "

Configuring a local or remote real server

When you define a real server, you specify whether the real server is local or remote:

• Local – A local server is one that is connected to the Brocade Virtual ADX at Layer 2. The

Brocade Virtual ADX uses local servers for regular load balancing.

• Remote – A remote server is one that is connected to the Brocade Virtual ADX through one or more router hops. The Brocade Virtual ADX uses remote servers only if all the local servers are unavailable.

NOTE

To use a remote server for regular load balancing, refer to “Primary and backup servers” on page 49.

Configuring a TCP MSS value at the global level

The default TCP MSS value configured on a Brocade Virtual ADX is 1460 Bytes. This value can be changed globally as shown in the following.

Virtual ADX(config)#tcp-mss 4000

Syntax: [no] tcp-mss mss-value

The mss-value variable specifies the global MSS value. This value can be from 576 to 9176.

Configuring a TCP MSS value for a virtual server

The default TCP MSS value configured on a Brocade Virtual ADX is 1460 Bytes. This value can be changed per virtual server as shown in the following.


Virtual ADX(config-vs-v1)#tcp-mss 4000


The mss-value variable specifies MSS value for all the real servers bound to the specified virtual server. This value can be from 576 to 9176.


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Configuring a TCP MSS value at the virtual server port level

The default TCP MSS value configured on a Brocade Virtual ADX is 1460 Bytes. This value can be changed per virtual server port as shown in the following.


Virtual ADX(config-vs-v1)#port http tcp-mss 4000

Syntax: [no] port virtual-server-port tcp-mss mss-value

The virtual-server-port variable specifies the TCP port that the MSS value will be applied to.

The mss-value variable specifies the MSS value for all the real server ports bound to the specified virtual server port. This value can be from 576 to 9176.

Configuring a TCP MSS value at the TCP profile level

The default TCP MSS value configured on a Brocade Virtual ADX is 1460 Bytes. This value can be changed per TCP profile as shown in the following.

Virtual ADX(config)#tcp profile tcp1

Virtual ADX(config-tcp-profile-tcp1)#tcp-mss 4000


The mss-value variable specifies the MSS value for all the real servers bound to the specified virtual server configured with the specific TCP profile. This value can be from 576 to 9176.

Support for TCP Window Scale option in TCP header

The TCP window scale option in TCP header feature optionally increases the definition of the maximum TCP window from 16 bits (65535) bytes by a window scale factor, to a theoretical maximum of (8388480 bytes). However, this theoretical value is limited by the maximum RX TCP buffer size of 3145278 bytes.

If this feature is not enabled, the maximum TCP window remains at 65535 bytes.

The window scale factor is expressed as a shift count - a power of 2. When enabled, the range of this count is from 1 to 7, i.e., from 2 to the power of 1 to 2 to the power of 7. Zero is the value of the default shift count, when TCP window scale is not specified

NOTE

The TCP window scale option appears in the SYN segment. Both ends of a TCP connection must send this option in their SYN segment. Otherwise window scaling is not enabled.


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Configuring TCP window scale option

To configure the TCP window scale option in the TCP header and change the receive and transmit buffer sizes, enter the following commands at the tcp profile name configuration level as shown in the example:

Virtual ADX(config)# tcp profile sample

Virtual ADX(config-tcp-sample)# tcp-wnd-scale 1

Virtual ADX(config-tcp-sample)# rxbuf-size 3145278

Virtual ADX(config-tcp-sample)# txbuf-size 3145278

Syntax: [no] tcp-wnd-scale window_scale_factor

The window_scale_factor variable specifies the TCP window scale factor from 1 to 7. The default is 0.

Syntax: [no] rxbuf-size buffer-size

The buffer-size variable specifies maximum TCP receive buffer size. Enter an integer from 0 to

3145278. The default is 0.

Syntax: [no] txbuf-size buffer-size

The buffer-size variable specifies maximum TCP transmit buffer size. Enter an integer from 0 to

3145278. The default is 0.

To display the TCP profile sample , enter the following show tcp profile command:

Virtual ADX# show tcp profile sample

TCP profile: sample

TCP Rx Buffer Size: 314278

TCP Tx Buffer Size: 314278

TCP Window scale factor: 1

Syntax: show tcp profile name

Binding a TCP profile to a virtual port and response rewrite policy

You can bind a TCP profile to a virtual port and response rewrite policy as shown in the following.


Virtual ADX(config-vs-v1)#port http response-rewrite-policy resp-1 tcp1

Syntax: [no] port virtual-port response-rewrite-policy response-rewrite-policy-name tcp-profile-name

The virtual-port variable specifies the TCP port that the specified TCP policy will be bound to.

The response-rewrite-policy-name variable specifies the response rewrite policy that the specified

TCP policy will be bound to.

The tcp-profile-name variable specifies the TCP policy that the specified response rewrite policy and virtual port will be bound to.


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Limiting the maximum number of TCP SYN requests

You can limit the maximum number of TCP SYN requests per second per server. A TCP SYN request is a packet a client sends requesting a TCP connection to the server.

To limit the maximum number of TCP SYN requests to 3500, enter the following command.

Virtual ADX(config)#server syn-limit 3500

Syntax: [no] server syn-limit max_requests

The max_requests variable is maximum number of TCP SYN requests per second per server. Enter an integer from 1 to 65535. The default value is 65535.

Configuring the maximum connection rate for a real server

Connection Rate Control (CRC) specifies the maximum number of new TCP, UDP, or individual port connections per second allowed on a real server.

It enables you to limit the connection rate to a real server for the following:

• All TCP traffic

• All UDP traffic

• Individual TCP or UDP ports

The Brocade Virtual ADX increments the connection counter for real server connections only after the Brocade Virtual ADX selects a server for the connection. If the Brocade Virtual ADX cannot serve a client request because a real server, cache, or firewall already has the maximum number of connections for the current second for the requested port, the Brocade Virtual ADX tries another server. If there are no servers available, the Brocade Virtual ADX sends a TCP RST to the client.

If you configure a limit for TCP or UDP and also for an individual application port, the Brocade

Virtual ADX uses the lower limit. For example, if you limit new TCP connections to a real server to

1000 per second and also limit new HTTP connections to 600 per second, the Brocade Virtual ADX limits connections to TCP port HTTP to 600 per second.

NOTE

The Brocade Virtual ADX counts only the new connections that remain in effect at the end of the one-second interval. If a connection is opened and terminated within the interval, the Brocade

Virtual ADX does not include the connection in the total for the server.

NOTE

Connection rates might not be strictly limited to the configured values. A slight drift can be introduced due to latency. For example, with traffic running at 1000 connections per second, and the max-tcp-conn-rate command is configured at 100, the connection rate could go up to 140.

To limit the number of new TCP and UDP connections a real server can receive each second, enter commands such as the following.

Virtual ADX(config)#server real RS1 10.2.3.4

Virtual ADX(config-rs-RS1)#max-tcp-conn-rate 1000

Virtual ADX(config-rs-RS1)#max-udp-conn-rate 800


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The first command limits new TCP connections to the real server to 1000 per second. The second command limits the rate of new UDP connections to the real server to 800 per second.

Syntax: max-tcp-conn-rate num

Syntax: max-udp-conn-rate num

The num variable specifies the maximum number of connections per second. There is no default.

The maximum connection rate that can be configured is 4294967295.

To limit the rate of new connections for a specific application port, enter commands such as the following.

Virtual ADX(config-rs-RS1)#port http

Virtual ADX(config-rs-RS1)#port http max-tcp-conn-rate 600

These commands add port HTTP (80) to the real server and limit the rate of new connections to the port to 600.

Syntax: port TCP/UDP-portnum max-tcp-conn-rate num

Syntax: port TCP/UDP-portnum max-udp-conn-rate num

The TCP/UDP-portnum variable specifies the application port.

The num variable specifies the maximum number of connections per second. The maximum connection rate that can be configured is 4294967295.

Configuring the maximum connection rate for a virtual server

You can specify the maximum allowed TCP or UDP connection rate for virtual servers. The Brocade

Virtual ADX monitors the traffic conditions and rejects new connections when the connection rate exceeds the limit.

To limit the number of new TCP or UDP connections that a virtual server can receive each second, use the max-tcp-conn-rate or max-udp-conn-rate command, respectively.

Virtual ADX(config)# server virtual-name-or-ip vs2 200.1.1.2

Virtual ADX(config-vs-vs2)# max-tcp-conn-rate 2000

Virtual ADX(config-rs-vs2)# max-udp-conn-rate 800

The first command limits new TCP connections to the server to 2000 per second. The second command limits the rate of new UDP connections to the server to 800 per second.

Syntax: max-tcp-conn-rate num

Syntax: max-udp-conn-rate num

The num variable specifies the maximum number of connections per second. There is no default.

Enter a number from 1 to 4294967295.

You can display the VIP TCP connection rate (tcp-conn-rate) and UDP connection rate

(udp-conn-rate) by using the show server virtual command.


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Disabling port translation

By default, the Brocade Virtual ADX translates the application port number requested by the client into the application port number you specify on the virtual server when you bind it to the real server. For example, if you bind port 80 on a virtual server to port 8080 on a real server, the

Brocade Virtual ADX translates the application port in the client’s request from port 80 into 8080 before forwarding the request to a real server.

A few Brocade Virtual ADX configurations require that you disable translation for an application port. For example, if you want to bind multiple virtual IP addresses to the same real server, you must disable port translation for all but one of the virtual IP addresses, then bind the virtual IP addresses to an alias port for the application. Disabling port translation enables the virtual IP addresses to use the same actual port number on the real server while the Brocade Virtual ADX collects and displays separate statistics for the alias port number associated with each virtual IP address.

To disable translation for an application port, enter commands such as the following.


Virtual ADX(config-vs-v1)#no port 80 translate

Syntax: [no] port tcp/udp-port translate

Traffic distribution among BPs

The Brocade Virtual ADX uses a hash algorithm to distribute traffic among barrel processors (BP). A default algorithm and 3 optional algorithms operate on the Source or Destination IP addresses to balance traffic among the BPs.

The default hash algorithm is “hash-crc32l”. In most situations, this setting will provide the most effective distribution of traffic across BPs. If you find however that traffic is not being efficiently distributed across the BPs on your Brocade Virtual ADX, you can try one of the other options.

To change the server hash algorithm from the default “hash-crc32l” to “hash-crc32u” use the following command.

Virtual ADX(config)#server hash-crc32u

Syntax: server hash-crc32l | hash-crc32u | hash-xorl | hash-xoru hash-crc32l: This algorithm performs CRC on the 32-bits of source IP in the forward direction and the 32-bits of Destination IP in the reverse direction. The lower five bits of the computed result are used to distribute traffic among BPs. This is the default setting.

hash-crc32u: This algorithm performs CRC on the 32-bits of source IP in the forward direction and the 32-bits of Destination IP in the reverse direction. The upper five bits of the computed result are used to distribute traffic among BPs. hash-xorl: This algorithm performs XOR on the 32-bits of source IP in the forward direction and the

32-bits of Destination IP in the reverse direction. The lower five bits of the computed result are used to distribute traffic among BPs.

hash-xoru: This algorithm performs XOR on the 32-bits of source IP in the forward direction and the

32-bits of Destination IP in the reverse direction. The upper five bits of the computed result are used to distribute traffic among BPs.


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Including the server client port in hash calculations

When there are a small number of client IP addresses that connect to a Brocade Virtual ADX, the traffic distribution of IP addresses to the BPs might not be optimal. Where this is the case, it can be useful to include the client source port in the hash calculations. This configuration is achieved by running the following command.

Virtual ADX(config)#server source-port-hash

Syntax: [no] server source-port-hash

NOTE

This command can be configured with any of the hash algorithms configured using the server hashxxx command described previously. This command cannot be used for protocols that involve dynamic ports such as FTP and RTSP, and with sticky features.

Sending ICMP Port Unreachable or Destination Unreachable messages

NOTE

ICMP messages are disabled by default.

By default, if the Brocade Virtual ADX receives a client request for a specific VIP and UDP port, but the requested port is not bound to the requested VIP, the Brocade Virtual ADX drops the packet. For example, if a client sends a request to VIP 10.10.5.1 and UDP port 99, but configuration for VIP

10.10.5.1 on the Brocade Virtual ADX does not include a binding for port 99, the Brocade Virtual

ADX drops the request without sending a message to the client.

You can configure the Brocade Virtual ADX to send an “ICMP Port Unreachable message” instead of dropping the packet without notice.

Also by default, if a client requests an unavailable TCP or UDP port, the Brocade Virtual ADX does not send an “ICMP Destination Unreachable message” to the client.

For HTTP traffic, you can configure the Brocade Virtual ADX to send such a message to the client, if the requested port either is not configured on any of the real servers or is unavailable because all the servers configured with the requested port are busy or down.

To configure the Brocade Virtual ADX to send “ICMP Destination Unreachable messages” to clients, or to send an “ICMP Port Unreachable message” when the device receives a request for a UDP port that is not bound to the requested VIP, enter the following command.

Virtual ADX(config)#server icmp-message

Syntax: [no] server icmp-message

NOTE

If server disable-ping-vip-down is configured, the Brocade Virtual ADX will stop responding to ICMP echo request when the VIP is down.


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Sending a TCP RST to a client that requests unavailable applications

If a client requests an unavailable application, the Brocade Virtual ADX does one of the following:

• Quietly drops the request.

• Sends an ICMP Destination Unreachable message (for UDP or TCP).

• Sends a TCP RST (for TCP only) – the default action.

Generally, an application is unavailable if all the real servers that have the application are unavailable or if the application is not configured on the VIP requested by the client.

To configure the Brocade Virtual ADX to send a TCP RST to a client, enter the following command.

Virtual ADX(config)#server reset-message

Syntax: [no] server reset-message

NOTE

The server reset message overrides the ICMP Destination Unreachable message. If the configuration contains both, the Brocade Virtual ADX sends a TCP RST instead of an ICMP message for TCP requests. For UDP requests, the device still sends ICMP messages. TCP RST does not apply to UDP.

For information on how to globally configure the Brocade Virtual ADX to send an ICMP Destination

Unreachable message to a client, refer to

“Sending ICMP Port Unreachable or Destination

Unreachable messages” on page 113.

Sending a TCP RST when TCP session entry ages out

By default, the Brocade Virtual ADX does not send a TCP RST to a client or server when its TCP session in the session table ages out.

You can enable the Brocade Virtual ADX to send a TCP RST to a client or server when a TCP session entry in use by the client or server ages out. To do this, enter the following command.

Virtual ADX(config)#server tcp-age reset

Syntax: [no] server tcp-age reset [both | client | server]

This command only works if you are running Layer 7 SLB.

The both option (default) enables the device to send messages to clients and servers.

The client option enables the device to send messages only to clients.

The server option enables the device to send messages only to servers.


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Disabling TCP RST message when a real server goes down during an open session

By default, if a real server goes down during an open TCP session with a client, the Brocade Virtual

ADX sends a TCP RST message to the client to terminate the session normally. When the real server comes back up, clients can establish a new session with the server.

You can globally disable the TCP RST message from being sent under these circumstances. When you disable the TCP RST message, the client can resume the interrupted session when the real server comes back up.

NOTE

Disabling the TCP RST messages affects only the message sent to a client when a real server goes down during a client’s session with the server. TCP RST messages sent under other circumstances are not affected.

To globally disable the TCP RST message from being sent, enter the following command.

Virtual ADX(config)#server no-reset-for-established-session

Syntax: [no] server no-reset-for-established-session

By default, sending TCP RST messages is enabled.

No TCP RST response to non-SYN first packet of a TCP flow

The Brocade Virtual ADX can remain passive for non-SYN packet in the beginning of the flow. The default behavior is to send a TCP RST packet to client when a non-SYN packet is received at the beginning.

By default, the Brocade Virtual ADX responds with a TCP RST packet whenever it receives a non-SYN TCP packet from a client destined for a VIP if there is no matching session.

If you want the Brocade Virtual ADX to remain passive, use the following command to ensure that no RST packet is sent to the client.

Virtual ADX(config)#server reset-on-syn-only

Syntax: [no] server reset-on-syn-only

Decrement counters in deletion queue

On a Brocade Virtual ADX, when a connection is closed, the corresponding sessions are not immediately deleted. The sessions are put in a deletion queue and deleted later at MSL time

(default is 8 seconds). Statistics on the closed connections are not adjusted until the sessions are actually deleted from the deletion queue.

To adjust statistics when sessions are put in the deletion queue, use the following command.

Virtual ADX(config)#server decrement-counter-when-put-in-delQ

Syntax: [no] server decrement-counter-when-put-in-delQ


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Optimized fast-path SLB processing

You can enable the Brocade Virtual ADX to use fast-path processing for stateful SLB. Stateful SLB is the standard form of SLB that uses session table entries to track session information. All traffic for stateful SLB takes an optimized processing path.

When you enable fast-path processing, the Brocade Virtual ADX does not process every TCP or UDP packet in a given session in detail. Instead, the Brocade Virtual ADX uses information gathered during setup of the session to forward packets in the session.

NOTE

SLB optimization is useful if simple stateful SLB is the primary or sole application on the device.

NOTE

Stateful SLB traffic is optimized by default.

Configuration considerations

Consider the following:

• Optimization applies only to SLB TCP or UDP traffic that is initiated by clients. Other types of traffic are not optimized.

• Optimization does not apply to fragmented IP packets.

• In the current release, the port name or number on the VIP must be same as the one on the real server bound to the VIP. Port translation is not supported.

• FTP traffic is not supported.

• Source NAT (source-nat command) is not supported.

• Host ranges (host-range command) are not supported.

• Many-to-one TCP or UDP port binding (no port tcp/udp-port translate command) is not supported.

NOTE

Traffic for an SLB configuration that does not meet these criteria is still forwarded using normal processing, but fast-path processing is not used.

Configuring TCP fast aging

Following a RST from the server, the Brocade Virtual ADX ages out session table entries in the amount of time specified in the server msl seconds command, by default 8 seconds. You can optionally configure the Brocade Virtual ADX to use the 1- to 2- minute aging time used in previous releases.

To set the amount of time a session table entry stays in the delete queue following a RST from the server, enter a command such as the following.

Virtual ADX(config)#server msl 2

Syntax: server msl seconds

The seconds variable can be from 1 through 180 seconds. The default is 8 seconds. Note that attempting to set the value to 0 resets the value to the default (8 sec.).


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To disable TCP fast aging and use the 1- to 2- minute aging time from previous releases, enter the following command.

Virtual ADX(config)#server no-tcp-fast-age-on-server-reset

Syntax: [no] server no-tcp-fast-age-on-server-reset

Server opt-enable-route recalculation

For optimized SLB, the Brocade Virtual ADX does not calculate a reverse route for every packet in a flow. In this scenario, the Brocade Virtual ADX uses the route that it learns in the first reverse packet, such as SYN-ACK packet. However, this calculation might not be desirable in a environment where a route can be dynamically changed, such as a case with upstream firewall failover, where the new firewall has the same IP address but a different MAC address. To cover these cases, the server opt-enable-route-recalculation command is used to force the Brocade Virtual ADX to dynamically calculate the reverse route.

In the case where the Server ADX only has Layer 4 SLB functionality, it will select an optimized way to accelerate the session handling by creating data sessions and remaining with the same ports for forwarding and reverse data traffic when the Brocade Virtual ADX receives the SYN packet. If later on, traffic needs to go through different ports, the traffic will fail. The server opt-enable-route-recalculation command is used to solve this problem by routing data out of the ports after recalculating the route. By enabling this command, however, the network performance will be affected.

NOTE

This command should be used only when there is a need to recalculate reverse route. Most situations do not require this.

Enabling use of the client MAC address

By default, the Brocade Virtual ADX uses the MAC address of its default gateway as the destination

MAC address for server replies (TCP SYN and TCP SYN ACK) to a client. You can enable use of the client MAC address instead of the default gateway address, by entering the following command.

Virtual ADX(config)#server l7-dont-use-gateway-mac

Syntax: [no] server l7-dont-use-gateway-mac

Enabling transparent VIP

Transparent VIP allows you to configure a Brocade Virtual ADX to transparently load balance a VIP, without owning the VIP address. Multiple Brocade Virtual ADX devices on which this virtual server is configured to be transparent can load balance requests for the server.

To configure an individual virtual server for the transparent VIP feature, enter a command such as the following.

Virtual ADX(config-vs-TransVIP)#transparent-vip

Syntax: [no] transparent-vip


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Enabling SYN ACK threshold

The SYN ACK threshold specifies the number of contiguous unacknowledged TCP SYN ACKs the

Brocade Virtual ADX allows to accumulate for a real server, before determining that the server is down and marking it FAILED. For examples and configuration information, refer to

“Reassign threshold” on page 220.

Syntax: server reassign-threshold number

The number variable specifies the number of contiguous unacknowledged TCP SYN ACKs for the threshold. Enter an integer from 6 to 4000. By default, the Brocade Virtual ADX assigns a threshold value of 20.

Replacing the source MAC address of the packet

When you configure the server source-mac-replacement command, if the incoming and outgoing

SLB traffic belongs to different VLANs, the source MAC address of the packet will be replaced using the Brocade Virtual ADX’s MAC address.

Virtual ADX(config)#server source-mac-replacement

Syntax: [no] server source-mac-replacement

Cloning real servers

To simplify configuration for large server farms, you can clone real servers. When you clone a real server, you make a copy of the real server configuration information under a new name. The copy includes the port bindings to the virtual server.

To clone a real server, enter commands such as the following.


Virtual ADX(config-rs-rs1)#clone-server rs2 10.6.7.8

The first command changes the CLI to the configuration level for the real server you want to copy.

The second command creates a clone of real server rs1. The clone is named "rs2" and has IP address 10.6.7.8.

Syntax: [no] clone-server name ip-addr

• The name variable specifies the name of the clone.

• The ip-addr variable specifies the IP address of the clone.

NOTE

To delete a server clone, you must manually edit the startup-config file to remove the command. The no option is not supported for this command.


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Configuring a host range

If you want to use the Unlimited VIP feature to load balance a large set of contiguous IP addresses on the real server, configure a host range to create a range of contiguous virtual IP addresses

(VIPs) based on the VIP address of the virtual server. The Brocade Virtual ADX creates the range by creating the number of VIPs that you specify with this command. You do not specify a range; you specify the number of hosts in the range. The beginning address in the range is always the VIP. The

IP addresses must be contiguous on the real server.

To define a range of 256 contiguous VIPs, enter commands such as the following.


Virtual ADX(config-rs-r1)#host-range 256





Virtual ADX(config)#server virtual-name-or-ip lotsofhosts 10.157.22.99

Virtual ADX(config-vs-lotsofhosts)#host-range 256

Virtual ADX(config-vs-lotsofhosts)#exit

Defining a host range simplifies configuration by allowing you to enter a single command or Web option for the whole range of addresses instead of entering information for each address individually.

You must also configure a corresponding range of addresses on the virtual server.

To configure a host range on a real server.



This command configures a range of 20 IP addresses, from 10.0.0.1 through 10.0.0.20.

Syntax: [no] host-range num

Unbinding all application ports from virtual servers

By default, a real server application ports remain bound to the virtual servers to which you bind them. You can unbind all of a real server’s application ports from the virtual servers.

To unbind a real server application ports, enter the following command at the configuration level for the server.

Virtual ADX(config-rs-R1)#port unbind-all

Syntax: port unbind-all

NOTE

Once you unbind the ports, you can rebind them only on an individual virtual server and port basis.

Identifying VIP port as TCP only or UDP only

You can explicitly identify an application port to be "TCP only" or "UDP only." The "TCP only" port accepts connections that arrive on TCP transport and drops connections that arrive on UDP transport. The ports that are identified as "UDP only" ports accept connections only on UDP transport:


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• Allow "TCP only" or "UDP only" port definitions under virtual server

• Allow similar definitions under real server also

On a Brocade Virtual ADX, when a port is defined under VIP, both UDP and TCP traffic with the port number are enabled and passed through to the real server. This scenario is not desirable in some cases.

As an enhancement, the user is allowed to define a TCP-only or UDP-only port so that only TCP or

UDP traffic with the specified port number can pass through. TCP-only or UDP-only traffic control has been supported internally on a Brocade Virtual ADX, but no CLI is available for the user to enable it.

As the enhancement, the following commands allow the user to enable or disable TCP-only or

UDP-only traffic control for a port defined under VIP.

Syntax: [no] port port tcp-only | udp-only

The command is available under VIP configuration mode.

When either TCP-only or UDP-only is configured, only TCP traffic or UDP traffic can pass through as configured; otherwise both TCP traffic and UDP traffic can pass through. TCP-only and UDP-only are exclusive, which means when TCP-only is configured, TCP-only and UDP-only cannot be configured for a particular port at the same time. UDP-only will be automatically disabled if TCP-only is configured, and vice versa.

Enabling fast aging for UDP sessions

When fast aging for UDP sessions is configured, a client request causes the Brocade Virtual ADX to add an entry to its session table; when a response is detected, the Brocade Virtual ADX immediately deletes the session table entry.

NOTE

Fast aging is the default behavior for the well-known DNS and RADIUS ports. To change DNS or

RADIUS to use the UDP age timer instead, refer to “Setting TCP and UDP ages for VIPs” on page 121.

When this feature is configured, if the Brocade Virtual ADX detects a server response to a client request, and the response is not fragmented, the session table entry is deleted immediately. If the response is fragmented, the Brocade Virtual ADX waits for the last fragment to arrive, forwards it to the client, and then sends the session to the delete queue. By default, the session stays in the delete queue for 8 seconds before being deleted. You can change the amount of time the session stays in the delete queue to between 1 and 40 seconds.

To activate fast aging for UDP sessions for port 1234, enter commands such as the following.


Virtual ADX(config-vs-vs1)#port 1234 udp-fast-age

Syntax: port UDP-portnum udp-fast-age

To set the amount of time sessions for ports configured with the udp-fast-age command stay in the delete queue before being deleted, enter the following command.

Virtual ADX(config)#server msl 2

Syntax: server msl secs

The secs variable can be from 1 to 40 seconds.


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Enabling normal UDP aging for DNS and RADIUS

By default, the Brocade Virtual ADX immediately deletes a UDP DNS or RADIUS session table entry when the Brocade Virtual ADX receives a reply for the application from a real server. You can configure the Brocade Virtual ADX to instead age out DNS or RADIUS sessions normally using the

UDP age timer.

To age DNS or RADIUS sessions using the UDP age timer, enter the following command at the global CONFIG level of the CLI.

Virtual ADX(config-vs-VIP1)#port dns udp-normal-age

Syntax: [no] port dns | radius udp-normal-age

For DNS and RADIUS UDP load balancing, unless the port is configured with this command, the

DNS or RADIUS sessions are always aged out after two minutes.

NOTE

By default, a Brocade Virtual ADX will exercise normal-age for DNS and RADIUS if the response is fragmented traffic from a real server. If you would like to enable the fast-age feature for fragmented traffic as well as non-fragmented traffic, you need to explicitly configure the udp-fast-age command on the port level.

Setting TCP and UDP ages for VIPs

The TCP and UDP ages specify how many minutes a TCP or UDP session can remain inactive before the Brocade Virtual ADX closes the session and clears the session from its session table. You can set the TCP or UDP ages for a specific virtual server, and you can set the TCP or UDP ages for an individual port on a virtual server.

NOTE

The session age is per minute and has a one minute range. For example, if you configured a TCP or

UDP age of three minutes for a virtual server, the age timeout is from two to three minutes.

For example, to set the TCP age for virtual server v1 to 20 minutes, enter the following commands.


Virtual ADX(config-vs-v1)#tcp-age 20

Syntax: [no] tcp-age minutes

To set the UDP age for virtual server v1 to 26 minutes, enter the following commands.


Virtual ADX(config-vs-v1)#udp-age 26

Syntax: [no] udp-age minutes

To set the TCP age for the HTTP port on virtual server v1 to 10 minutes, enter the following commands.


Virtual ADX(config-vs-v1)#port http tcp-age 10

Syntax: [no] port port tcp-age minutes

To set the UDP age for the SNMP port on virtual server v1 to 26 minutes, enter the following commands.


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Virtual ADX(config-vs-v1)#port snmp udp-age 26

Syntax: [no] port port udp-age minutes

You can set the TCP or UDP age from 2 through 60 minutes. The default TCP age is 30 minutes. The default UDP age is five minutes.

More specific settings override more general settings; that is, a TCP or UDP age setting for the HTTP port will override a TCP or UDP age setting for the virtual server, which will override the global TCP or UDP age (set with the server tcp-age or server udp-age commands).

Configuring session aging behavior

In stateful (default) mode, sessions are created when traffic flows through the Brocade Virtual ADX.

Two sessions are created for each flow: “forward” session (In Layer4 SLB, Client to VIP), and

“reverse” session (In Layer4 SLB, Real-Server to Client). These two sessions are tied together. Each session has an associated time after which the session is marked for removal. The session age is refreshed each time there is a new packet on the flow. The default mechanism to delete sessions is when both forward and reverse sessions reach their age limit.

You can use the following commands to change the default session aging behavior.

To age out forward and reverse sessions independently use the following command,

Virtual ADX(config)#server one-way-session-age

Syntax: server one-way-session-age

If one session ages out, delete that session but do not delete the other session.

To delete both sessions when any of the sessions ages out use the following command.

Virtual ADX(config)#two-way-session-age-on-one-age

Syntax: server two-way-session-age-on-one-age

Configuring DNS CPU-based throttling

DNS request processing time can become very slow when CPU utilization is at a high level (90 -

95%). With this feature you can direct a Brocade Virtual ADX to reject new DNS requests when CPU utilization goes beyond a configured threshold.

You can set DNS CPU-based throttling as shown.

Virtual ADX(config)#server throttle-on-overload 40

Syntax: [no] server throttle-on-overload cpu-percentage

The cpu-percentage variable specifies the threshold of CPU utilization when the Brocade Virtual

ADX will reject new DNS requests.

Limitation

This feature is applicable for UDP DNS only.


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NOTE

CPU utilization is not collected for every packet but every second. Consequently, the throttling decision might not always be accurate. Because of this, CPU utilization might go higher than the set threshold in some situations.

Configuring UDP DNS count connection

When a client’s UDP DNS traffic follows a pattern such that the 4 tuples (Source IP, Destination IP,

Source Port, Dest Port) are exactly the same across multiple DNS requests, the Brocade Virtual

ADX will have an issue. This is because the 5 tuples (SIP, DIP, SP, DP and protocol) based on which a new session is created by the Brocade Virtual ADX is no longer unique for the subsequent connections but will match the existing connection created by the first DNS request. When the first response is received from the real server, the session which was used by the multiple DNS connections will be deleted as expected. This leads to the subsequent response from the real server to not find a session and therefore will get the Layer 2 information forwarded instead of the translation from real server to the virtual IP (VIP). This will result in DNS responses reaching the client un-translated.

To resolve this, configure the Brocade Virtual ADX to keep a count of the number of UDP DNS connections used by the session and to delete the session only when all the responses to this session is received. Use the command at the global config level as shown.

Virtual ADX(config)#server dns-udp-count-connection

Syntax: [no] server dns-udp-count-connection

Dedicated next hop per VIP for reverse SLB traffic

This feature allows you to configure a default gateway for reverse SLB traffic at the Virtual server level.

To configure a virtual server with a next hop gateway use the command shown in the following.


Virtual ADX(config-vs-v1)#next-hop 10.1.1.100

Syntax: [no] next-hop next-hop-IPaddress

The next-hop-IPaddress variable specifies the IP address of the nest hop gateway for the virtual server.

NOTE

The IP address specified for the next-hop-IPaddress must be directly connected to the Brocade

Virtual ADX.

You can also configure the virtual server to allow it to fall back to its default gateway as shown in the following.


Virtual ADX(config-vs-v1)#next-hop-allow-fallback-to-default-gateway

Syntax: [no] next-hop-allow-fallback-to-default-gateway


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VIP route health injection

VIP route health injection (RHI) allows the Brocade Virtual ADX to advertise the availability of an

IPv4 or IPv6 VIP address (instead of a real host) throughout the network. Multiple Brocade Virtual

ADX devices with identical VIP addresses and services can exist throughout the network. This feature allows the Brocade Virtual ADX VIP to be used in lieu of the same VIP on other Brocade

Virtual ADX devices if the VIP is no longer healthy on those devices. A VIP can also provide the services because it is logically closer to the client systems than the other Brocade Virtual ADX devices.

Specifically, you can configure a Brocade Virtual ADX to check the health of a VIP configured on it and inject a VIP route into the network to force a preferred route to the VIP. VIP RHI checks the VIP health and reports one of the following:

• VIP is healthy. If the VIP is healthy, the Brocade Virtual ADX injects a VIP route into its route table for the VIP. The Brocade Virtual ADX then advertises the route to other routers using an

IGP routing protocol, such as OSPF or OSFPv3.

• VIP is not healthy. The Brocade Virtual ADX removes the IP route to the VIP from its route table.

As a result, the route is withdrawn by the routing protocols and is no longer used by upstream routers. The upstream routers instead use another route to the same VIP.

NOTE

IPv4 uses the OSPF routing protocol. For IPV6, the OSPFv3 routing protocol is used.

Routers receiving client traffic for the VIP select the best route to the VIP. As a result, clients enjoy fast response time regardless of their location, because their gateway routers use the best path to the VIP. RHI also prevents client traffic from being routed to a VIP that is unavailable.

VIP route health injection advertises the host route to the VIP instead of a network route to the VIP's subnet. This approach ensures that the clients' gateway routers receive a route to the IP address only if that VIP is available.

Configuration of VIP RHI is the same in most cases for IPv4 and IPv6 addresses. It is clearly shown in the following sections where there are differences in configuration commands or procedures.

NOTE

Disabling the real ports of all real servers using the server disable-all-real command causes the respective virtual port's RHI state to become "Not Healthy", and the VIP host route will not be advertised. In contrast, when you disable the virtual port of virtual server, the RHI state of a virtual port will not become "Not Healthy", and the Brocade Virtual ADX will keep advertising the VIP host route.

Injecting and deleting VIP route based on VIP health

The route for a VIP is injected when the VIP was previously unhealthy and is now deemed to be healthy. Similarly, the route for the VIP is withdrawn if it was previously healthy and is now down.

The health of a VIP is based on the health of its VIP ports. The health of a VIP port is based on the health of the real server ports bound to that VIP port.

You can configure any of the traditional health checks supported for the real servers. When a real server port fails the health check, the Brocade Virtual ADX will check if the real server port is bound to a VIP port whose VIP has the RHI feature enabled. If so, the Brocade Virtual ADX will determine how many real server ports bound to the VIP port are healthy. If the amount is below the threshold

(if percentage threshold is configured) or if none of the other real server ports are healthy (if


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Similarly, when a real server port transitions from the failed to the active state, the Brocade Virtual

ADX will check if the real server port is bound to a VIP port whose VIP has the RHI feature enabled.

If this is the case, the Brocade Virtual ADX will determine how many real server ports bound to the

VIP port are healthy. If you have configured a percentage threshold, and if this number is above the threshold, then Brocade Virtual ADX will declare this VIP port healthy. If you have not configured a threshold, then the Brocade Virtual ADX will declare this VIP healthy. If you have configured the option where a VIP should be considered healthy if at least one VIP port is healthy and the VIP was previously unhealthy, then it will inject the VIP route. If you have not configured this option (a VIP should be considered healthy only if all VIP ports are healthy), then the Brocade Virtual ADX will check if all other VIP ports are healthy. If they are, the Brocade Virtual ADX will inject the VIP route.

Configuration considerations

Before you enable RHI, consider the following three issues:

• Static route redistribution — It is required to redistribute the host route for the VIP into OSPF or

OSPFv3. To enable redistribution of static routes for IPv4, enter commands such as the following:

Virtual ADX(config)#router ospf

Virtual ADX(config-ospf-router)#area 0

Virtual ADX(config-ospf-router)#redistribution static

Syntax: [no] redistribution static

To enable redistribution of static routes for IPv6, enter commands such as the following:

Virtual ADX(config)#ipv6 router ospf

Virtual ADX(config-ospf6-router)#redistribute static

Syntax: [no] redistribute static

• Disabling network route advertisement for an interface associated with VIP RHI — The ip dont-advertise or ipv6 dont-advertise commands configure the Brocade Virtual ADX to block advertisement of the network on the interface. If you do not block advertisement of the network, the Brocade Virtual ADX will advertise a route to the network containing the VIP, even if the VIP itself is unavailable. After you enter the ip dont-advertise command, the Brocade

Virtual ADX advertises only a host route to the VIP address. Therefore, if the VIP is not healthy, the Brocade Virtual ADX will remove the static host route for the VIP address and also not advertise a network route for the network containing the VIP address.

NOTE

When using the dont-advertise commands, the IP or IPv6 and subnet mask length should be the same as the interface IP or IPv6 and subnet mask length.

For IPv4, enter commands similar to the following.

Virtual ADX(config)# interface ethernet 1

Virtual ADX(config-if-e1000-1)# ip address 10.1.1.99 255.255.255.0

Virtual ADX(config-if-e1000-1)# ip dont-advertise 10.1.1.99 255.255.255.0

Syntax: ip dont-advertise ip-addr mask I ip-addr / mask-bits


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For IPv6, enter commands similar to the following.

Virtual ADX(config)#interface loopback 1

Virtual ADX(config-lbif-1)#ipv6 address 2001:db8::1/64

Virtual ADX(config-lbif-1)#ipv6 dont-advertise 2001:db8::1/64

Syntax: ipv6 dont-advertise ipv6-prefix / prefix length

The following example of the display from the show ipv6 route command shows how dont-advertise routes are represented for IPv6 routes. As shown, the route type for these routes is “C (N)”.

Virtual ADX(config-lbif-3)#show ipv6 route

IPv6 Routing Table - 5 entries:

Type Codes: C - Connected, C(N) Connected(Dont-Advertise), S - Static, R -

RIP, O - OSPF, B - BGP, D - RA

Type IPv6 Prefix Next Hop Router Interface Dis/Metric

C 2001:DB8:3000::/64:: e 1 0/0

C 2001:DB8:4000::/64:: ve 40 0/0

C(N) 2001:DB8:4444::/64:: loopback 1 0/0

S 2001:DB8:4444::/96 2001:DB8:4444::110 loopback 1 1/1

C(N) 2001:DB8:6020::/78:: loopback 3 0/0

• Loopback interface, non-dangling VIPs, or dangling VIPs - For VIP RHI to work, you must configure a loopback interface or VE interface in the same subnet as the VIP subnet

(non-dangling VIP) or configure the VIP without any associated interface (dangling VIP

described in “VIP RHI with dangling subnets” on page 130).

The loopback interface or VE interface must have the ip dont-advertise command configured.

The following example configures a loopback interface to support two VIPs.

Virtual server 1 IP: 10.1.152.65

Virtual server 2 IP: 10.1.152.66

If the subnet of the VIPs is /30 then you need to configure either a VE interface or a loopback interface as follows:

Virtual ADX(config)#interface loopback 2

Virtual ADX(config-lbif-2)#ip address 10.1.152.67/28

Virtual ADX(config-lbif-2)#ip dont-advertise 10.1.152.67/28

Enabling or disabling VIP RHI

The Brocade Virtual ADX can enable VIP RHI globally or at the VIP sublevel for IPv4 hosts, IPv6 hosts or both. To enable VIP RHI feature globally for all IPv4 VIPs, enter commands such as the following.

Virtual ADX(config)#server global-advertise-vip-route v4-only

To enable VIP RHI feature globally for all IPv6 VIPs, enter commands such as the following.

Virtual ADX(config)#server global-advertise-vip-route v6-only

Syntax: [no] server global-advertise-vip-route [v4-only | v6-only | both]

The v4-only parameter enables VIP RHI globally or at the VIP sublevel for IPv4 hosts.

The v6-only parameter enables VIP RHI globally or at the VIP sublevel for IPv6 hosts.

The both parameter enables VIP RHI globally or at the VIP sublevel for IPv4 and IPv6 hosts.

If none of these parameters are specified, VIP RHI is enabled globally for IPv4 hosts only.


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NOTE

Where VIP hosts are classified as healthy, the Brocade Virtual ADX injects static host/subnet routes.

If a VIP is found to be unhealthy, RHI withdraws the static host/subnet route but the feature remains enabled. Using the no server global-advertise-vip-route command (IPv4 and IPv6) disables RHI and causes all routes that were injected by RHI because of the global-advertise command to be withdrawn. Routes injected by local advertise will still be in effect and will override the global advertise setting.

To enable VIP RHI for an individual virtual server, enter commands such as the following.


Virtual ADX(config-vs-vs1#advertise-vip-route

Syntax: [no] advertise-vip-route

NOTE

Where VIP hosts are classified as healthy, the Brocade Virtual ADX injects a static host/subnet routes only for the VIP specified by the advertise-vip-route command. If a VIP is found to be unhealthy, RHI withdraws the static host/subnet route for the host of the configured VIP but the feature remains enabled. Using the no advertise-vip-route command causes any routes for this VIP host injected by RHI to be withdrawn.

To disable VIP RHI for an individual virtual server, enter commands such as the following.


Virtual ADX(config-vs-vs1#disable-advertise-vip-route

Virtual ADX(config-vs-vs1)#end

Syntax: [no] disable-advertise-vip-route

This command is useful if you need to enable VIP RHI globally and disable it for a few virtual servers.

NOTE

Due to certain design restrictions, we advise that users turn off the RHI feature before modifying an interface configuration (on the interface to which the VIP is attached). After changes have been made to the interface configuration, you can turn the RHI feature on again. Following this method allows new VIP static routes to be recomputed and advertised while the old VIP routes are withdrawn. Use the Global and Local VIP advertise commands to turn the RHI on and off.

Defining the health of a VIP port

There are two options for defining VIP port health:

• By default, a VIP port will be considered healthy as long as there is at least one healthy real server port bound to it.

• You can define the percentage of bound real server ports that must be healthy in order to consider the VIP port healthy.

When you define the percentage of bound real server ports that must be healthy in order to consider the VIP port healthy, you can define this setting globally or per-VIP.


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Defining the health of a VIP port globally

To globally define the percentage of bound real server ports that must be healthy to consider a VIP port healthy, enter commands such as the following.

Virtual ADX(config)#server rhi-active-bindings-threshold 20

Syntax: [no] server rhi-active-bindings-threshold percent

Defining the health of a VIP port per VIP

To define the percentage of bound real server ports that must be healthy to consider a VIP port healthy for a specific VIP, enter commands such as the following.

Virtual ADX(config)#server virtual-name-or-ip dns-p1

Virtual ADX(config-vs-dns-p1)#rhi-active-bindings-threshold 30

NOTE

The VIP level configuration applies to all Virtual ports on the configured virtual server.

Syntax: [no] rhi-active-bindings-threshold percent

A valid range for percent is 1 through 100.

If the percent variable is not set, the percentage is 0. In this case, the default method will be used to determine the health of the VIP port. For example, a VIP port will be considered healthy as long as there is at least one healthy real server port bound to it.

As another example, consider a virtual server 10.1.1.101 with the port http command configured.

This port http of the virtual server is bound to port http of real server 10.1.1.15 and port http of real server 10.1.1.44. If you have not configured any active bindings threshold percentage, then port http of VIP 10.1.1.101 will be considered healthy as long as at least one of the two bound real server ports is healthy.

If you configure an active bindings threshold percentage of 100, then this setting requires all bound real server ports for the VIP port to be healthy in order to consider the VIP port healthy. If real server port http for real server 10.1.1.15 goes down, then VIP port http is no longer considered healthy because only 50 percent of the bound real server ports are healthy. The configuration in this example requires 100 percent of the bound real server ports to be up in order to consider the

VIP port as healthy.

Defining the health of a VIP

Multiple VIP ports can be configured for a VIP. There are two options provided for determining the health of a VIP:

• By default, a VIP will be considered healthy if all VIP ports for the VIP are healthy.

• You can specify a VIP to be considered healthy as long as there is at least one healthy VIP port.

To specify that a VIP should be considered healthy if at least one VIP port is healthy, enter commands such as the following.

Virtual ADX(config)#server rhi-one-vip-port-up

Syntax: [no] server rhi-one-vip-port-up

If this command is not configured, a VIP will be considered healthy only if all VIP ports are healthy.


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NOTE

If a VIP port is not bound to any real server ports, it will not be used for deciding the health of the VIP.

If a VIP port is bound but you do not want to use it to determine the health of the VIP as described above, then configure the following for the VIP port.

Virtual ADX(config)#server virtual-name-or-ip dns-p1

Virtual ADX(config-vs-dns-p1)#port ftp rhi-dont-use-port

Syntax: [no] port port rhi-dont-use-port

As another example, assume the port http and port ftp commands have been configured for virtual server vs1. You then bind port ftp of real server rs1 and port ftp of real server rs2 to port ftp of virtual server vs1. Similarly, you bind port http of real server rs1 and port http of real server rs2 to port http of virtual server vs1. If you need to base the health of the VIP vs1 only on the health of the

VIP port http, then you can configure the following for the port ftp.


Virtual ADX(config-vs-dns-p1)#port ftp rhi-dont-use-port

As a result, only the health of port http of virtual server vs1 will be used to determine the health of virtual server vs1 and consequently to determine if the VIP route for vs1 should be injected or withdrawn.

Configuring the VIP RHI Route Mask Length

You can configure the subnet mask length that VIP RHI injects into the routing table for a specific virtual server by entering a command such as the following.

Virtual ADX(config)#server virt virt-2

Virtual ADX(config-vs-virt-2)#vip-route-subnet-mask-length 28

Syntax: [no] vip-route-subnet-mask-length length

The ipv4-subnet-mask-length variable specifies the IPv4 subnet mask length of VIP RHI injected route for this virtual server. This parameter must have a value between interface subnet mask length and 32.

The ipv6-subnet-mask-length variable specifies the IPv6 subnet mask length of VIP RHI injected route for this virtual server. This parameter must have a value between interface subnet mask length and 128.

The server global-vip-route-mask-length command that configured the VIP RHI route mask length at a global level has been deprecated. This configuration will be translated to VIP level mask length under each individual VIP during image upgrade.

NOTE

The VIP-RHI mask length should not be less than the interface subnet mask length.

Depending on the interface mask length and the vip-route-mask length there can be either a host route or single/dual subnet routes to this VIP host.

Virtual ADX(config-vs-virt-2)#vip-route-subnet-mask-length 28

For example, If you have a VIP host with the IPv6 address “2001:DB8::10” configured over a loopback interface with the IPv6 address “2001:DB8::1/64” will, by default, RHI inject a static host route as shown.

S 2001:DB8::10/128 2001:DB8::10 loopback 1 1/1


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If you configure a vip-route-mask-length as “96” then when this VIP becomes healthy, an IPv6 subnet route with a mask length of “96” is advertised as shown.

S 2001:DB8::/96 2001:DB8::10 loopback 1 1/1

Where a user configures the vip-route-subnet-mask-length to the same values as the interface mask length, RHI injects two subnet static routes instead of one. In this situation the user will see two routes instead of one. For example, if the interface subnet mask length is “64” and the user configures the vip-subnet-mask-length as “64”, two routes will be advertised as shown below.

S 2001:DB8::/65

S 2001:DB8::80:0:0:0/65

2001:DB8::10

2001:DB8::10 loopback 1 1/1 loopback 1 1/1

Please note the subnet mask length of the above routes. When the user changes the VIP subnet mask length to and from being equal to the interface subnet mask length, the VIP static route injected will be corrected between dual routes and a single static route. This dual route extension was created to accommodate a larger range/number of VIP hosts within a subnet.

NOTE

One exception to the above dual route case is where value of the vip-route-subnet-mask-length command exceeds 125. In this situation, RHI will only inject host static routes.

NOTE

Use caution while configuring the vip-route-subnet-mask-length command value. Please make sure that the VIP subnets do not overlap with each other.

VIP RHI with dangling subnets

Normally a VIP with RHI should have an associated interface with an interface address (IPv4 or

IPv6) belonging to the VIP subnet. This means that at least one IP address belonging to the VIP subnet is consumed by the interface and cannot be used as a public address for the VIP server and

RHI has to depend on having an associated interface.

A user who does not wish to waste one public IP address to the interface can do so without adding any IP address in the VIP subnet. In this situation the VIP is deemed to be a “dangling VIP” (not associated with any interface). If the user adds an IP address in the VIP subnet to an interface, such a VIP is called a “non-dangling VIP”. The Brocade Virtual ADX supports both dangling and non-dangling VIPs. RHI determines the mode of the VIP at the time when advertise is enabled. The routes advertised also differ slightly in case of dangling VIPs as described in the following:

• Non-dangling VIPs: RHI will associate with the matching interface and set boundaries for the

VIP route to be advertised. In this case, RHI makes sure that it does not advertise a route bigger than the size of the associated subnet itself. This also includes advertising of dual routes. This configuration also allows dynamic-sym-priority to be bound with an associated interface status.

• Dangling VIPs: RHI will use the VIP-route-subnet-mask-length and blindly advertise a static route of that size. A user will see static routes with the next hop address as 255.255.255.255 in case of IPv4 VIP and :: (invalid IPv6 address) for an IPv6 VIP. In case of IPv4 the port value of the route shows “drop” and for IPv6 the port is “null”. In this mode dynamic-sym-priority is not bound to interface status.


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The following examples display how the output from the show ip route command will differ for the same destination address for non-dangling and dangling VIPs. Notice that for dangling VIPs the

“gateway” is specified as a non-valid route (IPv4 and IPv6). Also, the “interface” is specified as

“drop” for IPv4 and “null” for IPv6. Display of these values is normal for dangling VIPs.

Example of non-dangling VIPs

Virtual ADX#show ip route

Total number of IP routes: 1

Start index: 1 B:BGP D:Connected R:RIP S:Static O: OSPF *:Candidate default

Destination NetMask Gateway

1 10.1.1.0 255.255.255.0 10.1.1.105

Port

1b1

Cost

1

Type

S

Virtual ADX#show ipv6 route

IPv6 Routing Table - 1 entrie:

Type Codes: C - Connected, S - Static, R - RIP, O - OSPF, B - BGP, D - RA

Typ IPv6 Prefix Next Hop Router Interface Dis/Metric

S 2001:db8::10/128 2001:db8::10 loopback 1 1/1

Example of dangling VIPs



Start index: 1 B:BGP D:Connected R:RIP S:Static O: OSPF *:Candidate default

Destination NetMask Gateway Port

10.1.1.0 255.255.255.0 255.255.255.255

drop

Cost

1

Type

S

Virtual ADX#show ipv6 route

IPv6 Routing Table - 1 entrie:

Type Codes: C - Connected, S - Static, R - RIP, O - OSPF, B - BGP, D - RA

Typ IPv6 Prefix Next Hop Router Interface Dis/Metric

S 2001:db8::/64 :: null 1/1

Important caveats.

• Order of configuration is important in RHI. A user should choose between the two available modes (dangling and non-dangling) first and configure the interface and VIP RHI accordingly.

• Changing the interface configuration (for example: adding or deleting an IP address in the VIP subnet or disabling the interface) while the RHI is active is not recommended.

• To change the mode of the VIP, a user must remove RHI advertise first, change the interface configuration and then re-enable the RHI configuration. RHI computes the mode only at the time of enabling the RHI advertise option.


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VIP RHI and high availability topologies

• Hot Standby topology - VIP RHI is only supported on the Brocade Virtual ADX Router (R) platform. A Hot Standby topology is not supported for the R code base. Therefore, VIP RHI is not applicable to Hot Standby topologies.

• Symmetric and sym-active topologies - In both symmetric and sym-active topologies, only the owner of the VIP (the VIP in the active state) will inject the route. In this topology, the Brocade

Virtual ADX will withdraw the VIP route when a VIP transitions from Active to standby state.

Similarly, the Brocade Virtual ADX will inject the VIP route when a VIP transitions from Standby to Active, if the VIP is healthy at the time of the transition.

Optionally, you can enable a Brocade Virtual ADX to inject a VIP route inside the routing process regardless of its VIP ownership status. Enter the following command if you want to enable both

Brocade Virtual ADX devices to inject VIP route regardless of its ownership.

Virtual ADX(config)#server rhi-inject-always

Syntax: [no] server rhi-inject-always

Displaying route type

When VIP RHI is enabled for a virtual server, the VIP host route type is shown as "S:Static". The reason for doing this is the Brocade Virtual ADX can use redistribute static of routing protocols

(OSPF and RIP for IPv4 and OSPFv3 for IPv6) to advertise the VIP host route.

When the network route advertisement is disabled, the Brocade Virtual ADX shows the route's type as “D(N).”

The following output of the show ip route command is from a Brocade Virtual ADX with VIP RHI enabled.

.



Start index: 1 B:BGP D:Connected R:RIP S:Static O:OSPF *:Candidate

default

Destination NetMask Gateway Port Cost Type

1 10.20.1.0 255.255.255.0 0.0.0.0 v2 1 D

2 10.30.0.0 255.255.0.0 10.40.1.101 v1 2 O

3 10.40.1.0 255.255.255.0 0.0.0.0 v1 1 D

4 10.50.1.0 255.255.255.0 0.0.0.0 v4 1 D(N)

5 10.60.1.0 255.255.255.0 0.0.0.0 v3 1 D(N)

6 10.60.1.10 255.255.255.255 10.60.1.10 v3 1 S

7 10.70.1.0 255.255.255.0 0.0.0.0 3/12 1 D(N)

8 10.70.1.10 255.255.255.255 10.70.1.10 3/12 1 S

9 10.80.1.0 255.255.255.0 10.20.1.101 v2 2 O

10 10.90.1.0 255.255.255.0 0.0.0.0 3/12 1 D(N)

11 10.90.1.10 255.255.255.255 10.90.1.10 3/12 1 S


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The following snap shot of the show ipv6 route command was taken from a Brocade Virtual ADX with VIP RHI enabled.

Virtual ADX(config)#show ipv6 route

IPv6 Routing Table - 6 entries:

Type Codes: C - Connected, C(N) Connected(Dont-Advertise), S - Static, R - RIP,

O - OSPF, B - BGP, D - RA

Type IPv6 Prefix Next Hop Router Interface Dis/Metric

C 2001:db8:2001::/64:: ve 20 0/0

S 2001:db8:3001::/642001:db8:4001::101ve 40 1/1

C 2001:db8:3500::/64:: e 1/11 0/0

C 2001:db8:4001::/64:: ve 40 0/0

C(N)2001:db8:5000::/64:: loopback 1 0/0

C 2001:db8:bbbb::/64:: e 1/9T 0/0

Dob-4U-SI-A(config)#

NOTE

Some administrators might view this approach as a contradiction to the basic definition of a route type. The route type of a network that is owned by a Brocade Virtual ADX (router) is usually shown as

"D:connected" and a manually added static route type is to be shown as “S:Static.”

Configuration examples

Consider the example where VIP 10.1.1.10 is configured on three Brocade Virtual ADX devices (A, B and C). The following is the step-by-step VIP RHI configuration for Brocade Virtual ADX A.

1. Ensure a routing protocol is running, such as OSPF.

Virtual ADXA(config)#vlan 9

Virtual ADXA(config-vlan-9)#untagged ethernet 1

Virtual ADXA(config-vlan-9)#router-interface ve 1

Virtual ADXA(config-vlan-9)#exit

Virtual ADXA(config)#router ospf

Virtual ADXA(config-ospf-router)#area 0

Virtual ADXA(config-ospf-router)#redistribution static

Virtual ADXA(config-ospf-router)#exit

Virtual ADXA(config)#interface ve 1

Virtual ADXA(config-ve-1)#ip address 10.211.21.11 255.255.255.0

Virtual ADXA(config-ve-1)#ip ospf area 0

Virtual ADXA(config-ve-1)#exit

2. Configure the interface associated with the VIP.

Virtual ADXA(config)#interface loopback 1

Virtual ADXA(config-lbif-1)#ip address 10.1.1.99 255.255.255.0

Virtual ADXA(config-lbif-1)#ip dont-advertise 10.1.1.99 255.255.255.0

Virtual ADXA(config-lbif-1)#exit

3. Enable the real servers and ports.

Virtual ADXAconf t

Virtual ADXAconfig)#server real rs1 10.1.1.20

Virtual ADXA(config-rs-rs1)#port http

Virtual ADXA(config-rs-rs1)#exit

Virtual ADXA(config)#server real rs2 10.1.1.30

Virtual ADXA(config-rs-rs2)#port http

Virtual ADXA(config-rs-rs2)#exit


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4. Set the VIP, bind VIP ports to real server ports, and enable VIP RHI.

Virtual ADXA(config)#server virtual-name-or-ip vip-vadx-A 10.1.1.10

Virtual ADXA(config-vs-vip-vadx-A)#port http

Virtual ADXA(config-vs-vip-vadx-A)#bind http rs1 http rs2 http

Virtual ADXA(config-vs-vip-vadx-A)#advertise-vip-route

Virtual ADXA(config-vs-vip-vadx-A)#exit

The configuration is similar for Brocade Virtual ADX B and C (with relevant interface IP addresses).

Both Brocade Virtual ADX sites working in primary mode

FIGURE 22 Primary mode

134

Site 1 configuration

!

global-protocol-vlan

!

!

server predictor round-robin server global-advertise-vip-route v4-only server rhi-active-bindings-threshold 80


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server port 21 tcp server port 80 tcp server port 53 udp server port 161 udp server port 25 tcp server port 443 tcp server port 8601 tcp

!

!


port http port http url "HEAD /" port ftp port smtp port dns port dns zone "example9.com" port snmp port mms port rtsp

!



!

server real Web1 10.60.1.40

port 8601

!


port 8601

!


port 8601

!


port 8601

!


port 8601

!


port 8601

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port 8601

!


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Miscellaneous options server real Web8 10.60.1.47

port 8601

!


port 8601

!


port 8601

!

server remote-name rem1 10.80.1.40

port 8601 port ftp port smtp port ssl port dns port dns zone "example9.com" port snmp port mms port rtsp

!



!

!

server virtual-name-or-ip vip60 10.60.1.10

port http bind http Web1 8601 Web2 8601 Web3 8601 Web4 8601 bind http Web5 8601 Web6 8601 Web7 8601 Web8 8601 bind http Web9 8601 Web10 8601

!


vip-route-subnet-mask-length 28 port dns port snmp port http port ftp bind dns rem1 dns rem2 dns bind snmp rem1 snmp rem2 snmp bind http rem1 8601 rem2 8601 bind ftp rem1 ftp rem2 ftp

!


disable-advertise-vip-route port http port dns port snmp port ftp bind http rs1 http rs2 http bind dns rs1 dns rs2 dns bind snmp rs1 snmp rs2 snmp bind ftp rs1 ftp rs2 ftp


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!

vlan 1 name DEFAULT-VLAN by port

!

vlan 10 by port untagged ethe 1 router-interface ve 1

!

vlan 20 by port untagged 2 router-interface ve 2

!


!

hostname Site1-VADX router ospf area 0 metric-type type1 redistribution connected redistribution static

!

interface loopback 1 ip address 10.100.100.100 255.255.255.255

ip ospf area 0

!

interface ve 1 ip address 10.40.1.120 255.255.255.0

ip address 10.40.1.121 255.255.255.0 secondary ip ospf area 0

!



!


ip dont-advertise 10.60.1.120 255.255.255.0

ip address 10.60.1.121 255.255.255.0 secondary ip dont-advertise 10.60.1.121 255.255.255.0

!

end


!


!

!

server predictor round-robin server global-advertise-vip-route v4-only server rhi-active-bindings-threshold 80 server port 21 tcp server port 80


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Miscellaneous options tcp server port 53 udp server port 161 udp server port 25 tcp server port 443 tcp server port 8601 tcp

!

!



!



!


port 8601

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port 8601

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port 8601

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port 8601

!


port 8601

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port 8601

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port 8601

!


port 8601


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port 8601

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port 8601

!

!



!



!

!



!



!



!

!


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Miscellaneous options vlan 1 name DEFAULT-VLAN by port

!


!


!


!

hostname Site2-VADX

!

router ospf area 0 metric-type type1 redistribution connected redistribution static

!


ip ospf area 0

!



!



!




!

!

end


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Site 1 Brocade Virtual ADX in primary mode and Site 2 Brocade Virtual ADX in backup mode

FIGURE 23 Primary mode and backup mode


!


!

!

server predictor round-robin server global-advertise-vip-route v4-only server rhi-active-bindings-threshold 80 server port 21 tcp server port 80 tcp server port 53 udp server port 161 udp


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Miscellaneous options server port 25 tcp server port 443 tcp server port 8601 tcp

!

!



!



!


port 8601

!


port 8601

!


port 8601

!


port 8601

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port 8601

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port 8601

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port 8601

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port 8601

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port 8601

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port 8601

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port 8601

!

!

!

port ftp port smtp port ssl port dns port dns zone "example9.com" port snmp port mms port rtsp server virtual-name-or-ip vip60 10.60.1.10


!



!



!


!


!

vlan 20 by port


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Miscellaneous options untagged ethe 2 router-interface ve 2

!


!


!


ip ospf area 0

!



!



!




!

end


!


!

!

healthck Site1-chk icmp dest-ip 10.40.1.120

healthck Site1-NOT boolean not Site1-chk healthck Web1-8601-chk tcp dest-ip 10.60.1.40

port 8601 protocol http protocol http url "HEAD /" interval 20 retries 4 l7-check healthck Web2-8601-chk tcp dest-ip 10.60.1.41


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port 8601 protocol http protocol http url "HEAD /" interval 20 retries 4 l7-check


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Miscellaneous options healthck Web9-8601-chk tcp dest-ip 10.60.1.48


port 8601 protocol http protocol http url "HEAD /" interval 20 retries 4 l7-check healthck Web1-chk boolean and Site1-NOT Web1-8601-chk healthck Web2-chk boolean and Site1-NOT Web2-8601-chk healthck Web3-chk boolean and Site1-NOT Web3-8601-chk healthck Web4-chk boolean and Site1-NOT Web4-8601-chk healthck Web5-chk boolean and Site1-NOT Web5-8601-chk healthck Web6-chk boolean and Site1-NOT Web6-8601-chk healthck Web7-chk boolean and Site1-NOT Web7-8601-chk healthck Web8-chk boolean and Site1-NOT Web8-8601-chk healthck Web9-chk boolean and Site1-NOT Web9-8601-chk healthck Web10-chk boolean and Site1-NOT Web10-8601-chk

!

server predictor round-robin server global-advertise-vip-route v4-only server rhi-active-bindings-threshold 80 server port 21 tcp server port 80 tcp server port 53 udp server port 161


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udp server port 25 tcp server port 443 tcp server port 8601 tcp server real rs1 10.120.1.40


!



!


port 8601 port 8601 healthck Web1-chk

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port 8601


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Miscellaneous options port 8601 healthck Web7-chk

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disable-advertise-vip-route port http port dns


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port snmp port ftp bind http rs1 http rs2 http bind dns rs1 dns rs2 dns bind snmp rs1 snmp rs2 snmp bind ftp rs1 ftp rs2 ftp

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ip ospf area 0

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Application-specific SLB considerations

Application-specific SLB considerations

RTSP server load balancing

The Brocade Virtual ADX natively understands protocol RTSP and provides load balancing for it. The

Brocade Virtual ADX can also provide Layer 7 health checks for RTSP. Refer to “RTSP” on page 174

for details on Layer 7 health checks for RTSP.

If RTSP is bound to an unknown port, use the following command to provide RTSP server load balancing.

Virtual ADX(config)#server rtsp-for-unknown-port

Syntax: [no] server rtsp-for-unknown-port

NOTE

The Brocade Virtual ADX supports RTSP client port values of up to 9999. If the client is using a port number above 9999, you must configure the client to use a lower port value.

Deletion of UDP data session along with TCP control session for RTSP

The Brocade Virtual ADX tracks both control and data sessions for RTSP regardless of the underlying transport layer (TCP or UDP) used by these sessions. When the system deletes an RTSP control session (TCP based), it also deletes the respective data session (which can be UDP based).

Use the following command to enable this functionality.

Virtual ADX(config)#server rtsp-delete-udp-with-tcp-sess

Syntax: [no] server rtsp-delete-udp-with-tcp-sess

TFTP load balancing

TFTP load balancing is supported with health checks.

The Brocade Virtual ADX can conduct Layer 3 and Layer 4 health checks for TFTP ports.

When you configure a TFTP port and bind it to a Virtual server, the Brocade Virtual ADX does a Layer

3 check, and if this check passes, it does a Layer 4 check.

To check the health of a TFTP port, the Brocade Virtual ADX sends out a request for the SIcheck.txt file. The Brocade Virtual ADX does not actually interpret the reply packet. As long as it does not get an "ICMP dest or port unreachable" message, the Brocade Virtual ADX keeps the TFTP port up. If it gets an "ICMP unreachable" message, the Brocade Virtual ADX brings the TFTP port down.


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Show and debug commands

2

Show and debug commands

Refer to Appendix B, “SLB Show and Debug Commands” for a full list of show and debug

commands.

Displaying the BP distribution

To show how traffic is distributed across the multiple barrel processors for a given flow (IP addresses and L4 ports), use the following syntax:

Syntax: show bp-distribution type-of-traffic source-ip dest-ip source-l4-port dest-l4-port protocol

The type-of-traffic variable can take various values depending on the configuration parameters of the incoming traffic flow. The keywords for the type-of-traffic variable are listed as follows. all frag manual-holddown

Specifies the Catch-ALL entry due to cpu-forward

Specifies the Fragmentation entry

Specifies the Manual-Holddown entry real-server source-ip

Specifies the Real-Server entry (Reverse-SLB traffic)

Specifies the Source-IP entry (Reverse-SLB traffic with Source-NAT) static-nat Specifies the Static-NAT entry (Forward Static-NAT traffic) static-nat-reverse Specifies the Reverse Static-NAT entry (Reverse Static-NAT traffic) vip Specifies the VIP entry (Forward SLB traffic) vip-protection Specifies the VIP-Protection entry

The following example shows how to calculate the BP for a reverse-SLB flow coming from

Real-Server (10.1.1.1:80) to Source-NAT-IP (10.5.5.5) and displays which barrel processor the particular flow is landing on.

Virtual ADX(config)#show bp-distribution source-ip 10.1.1.1 10.5.5.5 80 2048

0 Packets for the specified flow map to: BP 1/1


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Displaying the BP distribution


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Stateless Server Load Balancing

Chapter

3

Overview

This chapter describes server load balancing configuration options that are “stateless.” Stateless

SLB does not use session table entries for the TCP or UDP sessions between the Brocade Virtual

ADX and clients or real servers.

These configuration options are useful if you want to deploy multiple Brocade Virtual ADX devices to provide service for the same VIPs or applications, but the network topology cannot ensure that server responses will pass back through the Brocade Virtual ADX.

NOTE

The Direct Server Return (DSR) feature allows you to deploy a single Brocade Virtual ADX in a network where the server responses do not pass back through the Brocade Virtual ADX. Compare the configuration example for Direct Server Return with the examples in this chapter to determine which type of configuration is applicable to your network. Refer to

“Configuring Direct Server Return” on page 57.

NOTE

The Brocade Virtual ADX does not support Stateless SLB with aliased ports, such as shown in the following configuration: server virtual-name-or-ip v3 10.176.7.23 port dns port dns stateless bind dns rs1 7777 real-port dns

Stateless TCP and UDP ports

You can configure a TCP application port to be stateless. When an application port is stateless, the

Brocade Virtual ADX does not create session table entries for the port. Configuring an application port to be stateless results in the following benefits:

• The server responses for the application can use alternate paths back to the client. For example, the Brocade Virtual ADX and real servers can be connected through a network that provides multiple return paths to the client. Because the port is stateless, the Brocade Virtual

ADX does not assume that the application is unhealthy if the server’s response does not flow back through the Brocade Virtual ADX.

• The Brocade Virtual ADX has more session resources available for application ports that need them.


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NOTE

The Direct Server Return feature also allows server responses to take paths that do not pass back through the Brocade Virtual ADX. However, Direct Server Return still uses session table resources because the Brocade Virtual ADX creates a session table entry for the connection from the client to the real server.

NOTE

The Brocade Virtual ADX supports port translation for stateless SLB. Port translation is useful when clients connect to real servers directly. Without port translation, if a client connects to a real server directly, the Brocade Virtual ADX automatically replaces the source IP address to a VIP. When you configure port translation, the Brocade Virtual ADX overcomes the limitation of performing NAT on all packets initiated from the real server. NAT does not occur because the Brocade Virtual ADX does not match the port number.

NOTE

The Brocade Virtual ADX supports stateless SLB for any TCP and UDP application protocols. For a

TCP application, hashing must be enabled on the Brocade Virtual ADX. For a UDP application, you can enable or disable hashing on the Brocade Virtual ADX.

NOTE

FTP and TFTP services do not maintain a fixed server port for responses. In such cases stateless mode cannot be used.

How the Brocade Virtual ADX selects a real server for a stateless port

The Brocade Virtual ADX does not use the standard SLB load-balancing methods when selecting a real server for a stateless application port. Instead, it uses hash values to select a real server. The

Brocade Virtual ADX calculates the hash value for a given client request based on the request’s source IP address and source TCP/UDP port.

The Brocade Virtual ADX has up to 8192 hash buckets (the default is 256) and divides the number of buckets evenly among the real servers. When the Brocade Virtual ADX forwards a client’s request for a stateless application port to the real server that corresponds to the calculated hash value, the Brocade Virtual ADX does not change the source address of the client’s request, but does change the destination address from the requested VIP into the real server’s IP address.

For example, when a Brocade Virtual ADX receives a request for TCP port 80 (HTTP) on VIP

(192.168.4.69) from client 10.161.1.88, the Brocade Virtual ADX calculates a hash value based on

10.161.1.88 and 80, then forwards the request to the real server that has the calculated hash value. The request packet is in the following format:

• Source IP: Client’s IP address

• Source application port: Port number selected by client’s application

• Destination IP: Real server’s IP

• Destination application port: Port number requested by client


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If client 10.161.1.88’s Web browser sent the request from TCP port 8080, and the Brocade Virtual

ADX’s hash calculation resulted in selecting real server 10.10.10.2, the packet would have the following address values:

• Source IP: 10.161.1.88

• Source application port: 8080

• Destination IP: Real server’s IP 10.10.10.2

• Destination application port: 80

Because the client’s request contains the client’s IP address and application port, the real server can send the packet back to the client along any valid routing path. The request does not need to pass back through the Brocade Virtual ADX that forwarded the request. In fact, the Brocade Virtual

ADX that forwards the requests to the transparent VIP does not create session table entries for the requests.

Because the Brocade Virtual ADX does not maintain state information for the requests for stateless application ports, the Brocade Virtual ADX does not care whether the server response for a stateless port passes back through the Brocade Virtual ADX on the way to the client. For a normally configured VIP, the server’s response passes back though the Brocade Virtual ADX. For a transparent VIP, the response does not necessarily pass back through the Brocade Virtual ADX.

NOTE

Because the Brocade Virtual ADX does not create session table entries for requests to the stateless application port, you cannot use Brocade Virtual ADX features that use information from the session table. For example, you cannot use source NAT, port translation, and similar features.

Configuring the stateless hash table size

You can configure the size of the stateless hash table as shown in the following:


Virtual ADX(config-rs-R1)#server stateless-hash-table-size 1024

Syntax: [no] server stateless-hash-table-size table-size

The table-size variable can be set to any of the following values: 256, 512, 1024, 2048, 4096, or

8192.

The default value is 256.

Configuring a stateless application port

To configure an application port to be stateless, enable the stateless parameter on the port in the virtual server as shown in the following example.







Virtual ADX(config)#server virtual-name-or-ip StatelessHTTP 192.168.4.69

Virtual ADX(config-vs-StatelessHTTP)#port http stateless




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Syntax: [no] port tcp/udp-portnum stateless

The tcp/udp-portnum variable specifies the application port you want to make stateless.

Disabling the stateless SLB hashing algorithm for UDP ports

By default, stateless SLB uses a hashing algorithm to select a real server. The Brocade Virtual ADX calculates a hash value for a given client request based on the request’s source IP address and source TCP/UDP port. The request is sent to a real server corresponding to this hash value.

For UDP connections consisting of one client packet and one server response packet, you can disable the stateless SLB hashing algorithm. When the stateless SLB hashing algorithm is disabled for UDP ports, the Brocade Virtual ADX uses the round-robin load balancing method to select a real server for the request. In this case, the Brocade Virtual ADX load balances UDP packets destined for the VIP without creating a session and without calculating hash values based on UDP port number and source IP address.

DNS is an example of a UDP port where this feature can be used. The advantage of disabling the stateless SLB hashing algorithm is that a new real server can be selected immediately after it is brought up.

For example, to disable the stateless SLB hashing algorithm for the DNS port (UDP port 53), enter commands such as the following:

Virtual ADX(config)#server virtual-name-or-ip Stateless 192.168.4.69

Virtual ADX(config-vs-Stateless)#port dns stateless no-hash

Syntax: [no] port udp-portnum stateless no-hash

NOTES: When this command is applied, in some cases it will not take affect. This occurs if the sessions are stuck and it requires you to clear the sessions first and then apply the command, as described in the following.

1. Disable the real server and unbind the VIP.

2. Clear the sessions using the clear server sessions real server name command.

3. Apply the stateless no-hash command, bind the real servers to the VIP and enable the real server.

Configuring a port to be both stateless and stateful

You can use the stateless option when configuring an application port on a virtual server to make that port stateless. By default, the port is stateless for both TCP and UDP. You can also specify the protocol for which you want the port to be stateless. For example, you can configure port DNS to be stateless for TCP while remaining stateful for UDP, by entering commands such as the following.







Virtual ADX(config)#server virtual-name-or-ip StatelessDNS 192.168.4.69

Virtual ADX(config-vs-StatelessDNS)# port dns stateless tcp

Virtual ADX(config-vs-StatelessDNS)#bind dns R1 dns

Virtual ADX(config-vs-StatelessDNS)#bind dns R2 dns

Syntax: [no] port tcp/udp-port [stateless [tcp | udp] [no-hash]]


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The tcp/udp-port variable specifies the application port you want to make stateless.

The stateless parameter configures the port to be stateless.

The tcp | udp parameter restricts stateless operation to the specified protocol (TCP or UDP).

The no-hash parameter disables the SLB hashing mechanism for the port (and protocol, if specified). When hashing is disabled, the Brocade Virtual ADX uses the round-robin load balancing method to select a real server for each request.

Clearing a virtual port’s stateless hash table

You need to clear the virtual port’s stateless hash table after a specified time interval anytime a binded real server port becomes active (from a non-active state) in order to incorporate the port into the stateless hash table. Use the command as shown in the example:

Virtual ADX(config)#server virtual-name-or-ip StatelessDNS 192.168.4.69

Virtual ADX(config-vs-StatelessDNS)#port dns stateless clear-stateless-hash 1000

Syntax: [no] port tcp/udp-port stateless clear-stateless-hash timeout

The timeout variable is specified in number of seconds. Enter an integer from 0 to 65535.

Fragmentation support in the stateless mode

By default, fragmentation is not supported in the stateless server load balancing mode.

Consequently, fragmented packets are dropped. This feature allows you to configure fragmentation support for a specified port in the stateless mode.

This support is necessary in situations where packets exceed the default size and need to be fragmented. For example, DNSSEC adds security headers in the DNS response that make the packet exceed the default packet size (512 Bytes) which causes packet fragmentation. Because of this, DNSSEC messages will be dropped unless Fragmentation support is enabled.

Configuring fragmentation support in the stateless mode

Using this feature, stateless fragmentation support can be provided for a specified port within a

VIP. To enable fragmentation support in the stateless mode, use the following command.

Virtual ADX(config)#server virtual v1 10.10.10.1

Virtual ADX(config-vs-v1)#port dns stateless frag-support

Syntax: [no] port port-name stateless frag-support

The port-name variable specifies the port in the stateless mode that is being enabled for fragmentation.

Feature limitations

• One real server cannot be bound to multiple VIPs even for a different service. This means that, given a real server IP, there is only one VIP that is bound to this real server.

• Fragmented pass-through traffic is not supported.

• For L7 switching for a different port under the same VIP, Brocade highly recommends using another VIP.


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• Connections originating from real server ports other than the ports configured on the Brocade

Virtual ADX as real server ports are not supported when fragmented.

Example

VIP: 10.11.1.1:80 rs1 10.1.1.1:80 and rs2 10.1.1.2:80

In this configuration, packets from rs1 and rs2 with a source port other than port 80 will exhibit unpredictable behavior when they are fragmented.

In these cases, configure the virtual server as a statefull virtual server.


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Health Checks

Chapter

4

Health checks overview

The Brocade Virtual ADX uses Layer 3, Layer 4, and Layer 7 health checks to verify the availability of real servers and of applications on the real servers.

When you configure a real server, the Brocade Virtual ADX first sends an ARP request for the real server and then sends an IP ping to the server, to verify that the Brocade Virtual ADX can reach the server through the network. The ARP request is sometimes referred to as a Layer 2 health check because the request is for the real server’s hardware layer address.

Later, when you bind the real server to a Virtual IP (VIP) server, the Brocade Virtual ADX sends a

Layer 4 or Layer 7 health check to bring up the port you used for the binding. For example, if you bind a real server to a virtual server using port HTTP, the Brocade Virtual ADX sends an HTTP Layer

7 health check to bring up the HTTP port on the real server.

The Brocade Virtual ADX performs the health checks described above by default. In addition, you can enable periodic Layer 4 or Layer 7 keepalive health checks for individual application ports.

After successful bringup of an application port when you bind a real server to a virtual server, the

Brocade Virtual ADX repeats the Layer 4 or Layer 7 keepalive health check to continually verify the health of the port.

Layer 3 health checks

Layer 3 health checks consist of ICMP-based IP pings and ARP requests. When you configure a real server on the Brocade Virtual ADX, the Brocade Virtual ADX sends an ARP request and an IP ping to the real server to verify that the Brocade Virtual ADX can reach the server through the network.

The Brocade Virtual ADX also sends an IP ping to a real server in the following circumstances:

• If the ARP entry for the server times out, the Brocade Virtual ADX uses the IP ping to create a new ARP entry for the server. The ARP request is sometimes referred to as a Layer 2 health check because the request is for the real server’s hardware layer address.

• If the time between the last packet sent to the server and the last packet received from the server increases, the Brocade Virtual ADX uses the IP ping to determine whether the slowed response time indicates loss of the server. If the server responds to the ping, the Brocade

Virtual ADX then sends a Layer 4 or Layer 7 health check, depending on whether the port’s application type is known to the Brocade Virtual ADX. The Brocade Virtual ADX sends pings at an interval of 2 seconds apart, and retries unsuccessful pings up to 4 times by default. You can

change the ping interval and retries if desired. Refer to “Modifying the ping interval and ping retries” on page 161.

The following Layer 3 health check types are supported:

• ARP Request

• IP Ping


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Table 13 summarizes the Layer 3 health checks.

TABLE 13 Summary of Layer 3 health checks

Type Description

ARP request A standard IP ARP request for the server’s MAC address, which the Brocade Virtual ADX adds to its

ARP table.

IP ping A standard ICMP-based IP ping.

When performed

•

When you configure a real server

•

When you configure a real server

•

If the ARP entry ages out

•

If the time between the last packet sent to the server and the last packet received from the server increases

Disabling Layer 3 health checks

By default, when you add a real server configuration to the Brocade Virtual ADX, the Brocade

Virtual ADX uses a Layer 3 health check (IP ping) to determine the server’s reachability. If the real server responds to the ping, the Brocade Virtual ADX changes the server’s state to ACTIVE and begins using the server for client requests.

You can globally disable the Layer 3 health check for local servers or remote servers. You also can disable the Layer 3 health check on individual real servers. When you disable the Layer 3 health check, the Brocade Virtual ADX sends an ARP request for the default gateway and makes the server’s state ACTIVE for as long as the ARP entry remains in the Brocade Virtual ADX’s ARP cache.

To globally disable the Layer 3 health check for all local real servers, enter the following command.

Virtual ADX(config)#server no-real-l3-check

Syntax: [no] server no-real-l3-check

To globally disable Layer 3 health check for all remote real servers or of IP addresses learned through GSLB, enter the following command.

Virtual ADX(config)#server no-remote-l3-check

Syntax: [no] server no-remote-l3-check

NOTE

The server no-remote-l3-check command also disables Layer3 health checks of IP addresses learned through GSLB.

To disable the Layer 3 health check on an individual real server, enter the following command.

Virtual ADX(config-rs-R1)#no-l3-check

Syntax: [no] no-l3-check

This command applies to local real servers and remote real servers.


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Modifying the ping interval and ping retries

The Brocade Virtual ADX automatically uses a Layer 3 health check, consisting of ICMP echo requests (pings), to check the health of a real server. Ping is enabled by default. However, you can modify the ping interval and the number of retries.

To modify the ping interval, enter the following command.

Virtual ADX(config)#server ping-interval 8

Syntax: [no] server ping-interval value

The value variable can be a value from 1 through 10 seconds. The default is 2 seconds.

To modify the number of times the Brocade Virtual ADX will ping a real server before changing the server state to FAILED, enter the following command.

Virtual ADX(config)#server ping-retries 7

Syntax: [no] server ping-retries value

The value variable can be a value from 2 through 10. The default retry value is 4.

Setting the Periodic ARP Interval

You can configure the periodic ARP interval.The default interval for periodic ARPs is 20 seconds. To configure the periodic ARP interval, use the following command.

Virtual ADX(config)#server periodic-arp-interval 14400

Syntax: server periodic-arp-interval seconds

The seconds variable specifies the ARP interval. Enter an integer from 10 to 14400.


When you bind a real server to a virtual server, the Brocade Virtual ADX performs either a Layer 4

TCP health check, a Layer 4 UDP health check, or a Layer 7 health check to bring up the application port that binds the real and virtual servers. If the application port is not one of the applications that is known to the Brocade Virtual ADX, the Brocade Virtual ADX uses a Layer 4 health check.

Otherwise, the Brocade Virtual ADX uses the Layer 7 health check for the known application type.

The Layer 4 health check can be a TCP check or a UDP check:

• TCP health check – The Brocade Virtual ADX checks the TCP port’s health based on a TCP three-way handshake:

The Brocade Virtual ADX sends a TCP SYN packet to the port on the real server.

The Brocade Virtual ADX expects the real server to respond with a SYN ACK.

If the Brocade Virtual ADX receives the SYN ACK, the Brocade Virtual ADX sends a TCP

RESET, satisfied that the TCP port is alive.


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• UDP health check – The Brocade Virtual ADX sends a UDP packet with garbage (meaningless) data to the UDP port:

If the server responds with an ICMP “Port Unreachable” message, the Brocade Virtual ADX concludes that the port is not alive.

If the server does not respond at all, the Brocade Virtual ADX assumes that the port is alive and received the garbage data. Because UDP is a connectionless protocol, the Brocade

Virtual ADX and other clients do not expect replies to data sent to a UDP port, so a lack of response indicates a healthy port.

NOTE

The Brocade Virtual ADX assumes that a port is a UDP port unless you configure the port as a TCP port. To configure a port as a TCP port, add a port profile for the port and specify the port type TCP.

Refer to “Basing a port’s health on the health of another port” on page 220.

After the Brocade Virtual ADX sends an initial packet (TCP or UDP) to the server to bring the port up, the Brocade Virtual ADX waits one second and then checks for a response from the server. If no response is received during that time, the Brocade Virtual ADX will send another packet. The time at which the Brocade Virtual ADX sends the second packet depends on the number of ports being brought up at that time. The Brocade Virtual ADX will send the second packet after it has sent initial packets to all the other ports being brought up at that time.

By default, the Brocade Virtual ADX does not repeat the Layer 4 health check after bringing up the port when you bind the real server to the virtual server. However, you can enable a periodic keepalive health check for the port. To configure the keepalive health check globally, configure a port profile for the port. You also can enable or disable the keepalive health check on individual real servers.


• TCP

• UDP


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Table 14

describes the Layer 4 health check types performance and its description.

TABLE 14 Summary of Layer 4 health checks

Type When performed

TCP

•

When you bind a TCP application port on a real server to a TCP application port on a virtual server

•

At regular intervals, if keepalive is enabled for the port and the port does not have a Layer 7 health check

UDP

•

When you bind a UDP application port on a real server to a UDP application port on a virtual server

•

At regular intervals, if keepalive is enabled for the port and the port does not have a Layer 7 health check

Description

The Brocade Virtual ADX attempts to engage in a normal three-way TCP handshake with the port on the real server:

•


•


•

If the Brocade Virtual ADX receives the SYN ACK, the

Brocade Virtual ADX sends a TCP RESET, satisfied that the TCP port is alive.

The Brocade Virtual ADX sends a UDP packet with garbage

(meaningless) data to the UDP port.

•


•

If the server does not respond at all, the Brocade

Virtual ADX assumes that the port is alive and received the garbage data. Since UDP is a connectionless protocol, the Brocade Virtual ADX and other clients do not expect replies to data sent to a UDP port. Thus, lack of a response is a good outcome.

Performing Layer 4 UDP keepalive health checks for the DNS port

You can configure the Brocade Virtual ADX to perform Layer 4 UDP keepalive health checks for the

DNS port (port 53).

To do this globally for the DNS port on all real servers, enter the following commands:

Virtual ADX(config)#server port dns

Virtual ADX(config-port-dns)#udp l4-check-only

NOTE

The l4-check-only command does not apply to the RADIUS protocol.

By default, the Brocade Virtual ADX performs a Layer 4 TCP health check whenever the DNS port on a real server is brought up.

To configure the Brocade Virtual ADX to perform a Layer 4 UDP health check on the DNS port whenever it is brought up, add the no tcp keepalive enable command to the DNS port profile as in the following example:


Virtual ADX(config-port-dns)#no tcp keepalive enable


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Server response threshold health check

The Brocade Virtual ADX distributes traffic among real servers based on a dynamic weight value derived from the caculated response time of health check packets. Using the same calculated response times, the Brocade Virtual ADX can perform Layer 4 and Layer 7 health checks.

The Brocade Virtual ADX calculate Layer 4 and Layer 7 response times and compares those with the configured response threshold. If the calculated response time is greater than the configured response threshold, the port is marked DOWN.

The Brocade Virtual ADX calculates Layer 4 and Layer 7 response times differently:

• Layer 4 response times (round trip times) measure the time between the sending of a SYN packet and receiving a SYN ACK packet.

• Layer 7 response times measure the time between the L7 request and the first response packet returned to the server. In the case of an LDAP server, this is the time between a bind request and bind reply. For HTTP servers, this is the time between sending a GET or HEAD request and the first packet received from server.

The calculated response time is compared to a user-configured response threshold. You can configure a Layer 4 response threshold, a Layer 7 response threshold, or a combined Layer 4 and

Layer 7 response threshold.

To define the server response threshold, enter commands such as the following.


Virtual ADX(config-rs-r1)#port http response-threshold layer4 200

Virtual ADX(config-rs-r1)#port http response-threshold layer7 800

Syntax: [no] response-threshold {layer4 | layer7 | layer4&7} threshold-value

The layer4 keyword specifies a Layer 4 response threshold. The layer7 keyword specifies a Layer 7 response threshold. The layer4&7 keyword specifies combined Layer 4 and 7 response threshold.

The threshold-value variable is the server response threshold in microseconds. Enter an integer from 1 to 50,000.

Debugging and testing

The show server real command displays health check counters for the port and all servers which you can use when you test or debug response threshold health checks.

Syntax: show real server portnum | port-name


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To display configuration information and statistics for the real server configured on the Brocade

Virtual ADX, enter the following command:

Virtual ADX(config)#show server real http

HTTP keepalive statistics:

HTTP statistics:

URL replace cs: test = 3, fail = 0, malloc fail = 0 checksum: tested = 1, fail = 0, malloc fail = 0

No free ka port = 0, content match alloc fail = 0

Content match malloc = 0, free = 0

Bring port down = 0, retries = 0

TCP bring up statistics:

send buf alloc fail = 0, tcp send fail = 0

Test ka port index null = 0, Tcp conn ka index null = 0

Server close = 0

Suc: ka port index null = 0 test port index null: suc cb = 0, rec cb = 0, fail cb = 0

TCP keepalive statistics:

tcb alloc = 0, free = 0, fail = 0

tcb free when state: not active = 0, not bind = 0

suc cb : real port null = 0, ka port null = 0, ka port invalid = 0

rec cb : real port null = 0, ka port null = 0, ka port invalid = 0

fail cb : real port null = 0, ka port null = 0, ka port invalid = 0

conn compl cb : real port null=0, ka port null = 0, ka port invalid =0

tcb mismatch: suc cb = 0, rec cb = 0, fail cb = 0, conn compl cb = 0

real port null = 0, ka port mismatch = 0, ka port invalid = 0

send buf alloc fail = 0, tcp send fail = 0

Server close = 0

Real port not match = 0

TCP statistics:

tcp keep alive: close connection 0, remote close 0

tcp connect: connection exist 0, out of tcb 0

tcb: alloc 4, free 0

Slot index 4

Real server name = r1, Real port Status = NOT BOUND

Slot valid = TRUE IP: 10.10.10.10

Real port index = 7, Real port no = 80

Tcp request = 0, Tcp response = 0

Tcp response timeout = 0, Keepalive Enabled

HTTP URL = "HEAD /example1.com"

HTTP sent = 0, Received ok = 0

HTTP received error = 0, Receive timeout = 0

wait for response = FALSE, Status code = 0

Server close = 0, Current sent = 0

Bring port down = 0, Total retries = 0

TCP RTT = 0 us, Appl RTT = 0 us

Current TCP RTT = 0 us, Current Appl RTT = 0 us

Bring port down for RTT= 0 Next slot index = 0

The fields in bold provides the following information:

• The Bring port down for RTT field displays the number of times the port has been marked down because it has exceeded the configured response threshold. This can be Layer 4, Layer 7, or combined Layer 4 and 7.

• The Current TCP RTT field displays in microseconds the current TCP round trip time. If this value exceeds the configured l4 response threshold, the port is brought down.


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• The Current Appl RTT field displays in microseconds the current application round trip time. If this value exceeds the configured l7 response threshold, the port is brought down.

• The TCP RTT field is a smoothed l4 round trip time that is used by the response time predictor.

• The Appl RTT field is a smoothed l7 round trip time that is used by response time predictor.

Displaying health check related error messages

The server debug hc-error command, when enabled, displays health-check related error messages to the console.

Syntax: server debug hc-error


For certain TCP and UDP application ports, the Brocade Virtual ADX can send application-specific health checks to determine the health of the application. For example, the Brocade Virtual ADX can send user-configurable HTTP requests to real servers to assess the health of the servers.

When you bind a real server to a virtual server using an application port that is known to the

Brocade Virtual ADX, the Brocade Virtual ADX sends a Layer 7 health check to the application on the real server to bring up the application port.

By default, if a client requests a TCP/UDP port that is not available, the Brocade Virtual ADX does not send an ICMP “Destination Unreachable” message to the client. For HTTP traffic, you can configure the Brocade Virtual ADX to send such a message to the client by enabling the ICMP

Message feature for HTTP. Refer to “Sending ICMP Port Unreachable or Destination Unreachable messages” on page 113 for details.

You can enable a Layer 7 health check globally by configuring a port profile or locally by enabling the health check on an individual real server. In addition, you can customize some types of Layer 7 health checks for individual real servers. For example, you can specify a URL that the Brocade

Virtual ADX should request on a specific real server when sending the Layer 7 HTTP health check to that server.


•

“DNS” on page 168

•

“FTP” on page 169

•

“HTTP (status code)” on page 169

•

“HTTP (content verification)” on page 170

•

“HTTP (status code)” on page 169

•

“HTTP (content verification)” on page 170

•

“Scripted (content verification for unknown ports)” on page 170

•

“IMAP4” on page 171

•

“LDAP” on page 171

•

“MMS” on page 172

•

“NNTP” on page 173

•

“PNM” on page 173

•

“POP3” on page 173


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•

“RADIUS” on page 174

•

“RTSP” on page 174

•

“SMTP” on page 175

•

“SSL (complete)” on page 175

•

“SSL (simple)” on page 176

•

“Telnet” on page 176

Application ports

The Brocade Virtual ADX selects a Layer 4 or Layer 7 health check based on whether the application port is known to the Brocade Virtual ADX. A Layer 4 health check is a TCP or UDP request and is not related to a specific application. A Layer 7 health check is an application-aware health check designed for the specific application. The following application ports are known to the

Brocade Virtual ADX. The Brocade Virtual ADX performs Layer 7 health checks for these ports. For other ports, the Brocade Virtual ADX performs a Layer 4 TCP or UDP health check instead.

• FTP (port 21). Ports 20 and 21 both are FTP ports but on the Brocade Virtual ADX, the name

“FTP” corresponds to port 21.

• HTTP (port 80)

• IMAP4 (port 143)

• LDAP (port 389)

• MMS (port 1755)

• NNTP (port 119)

• PNM (port 7070)

• POP3 (port 110)

• RTSP (port 554)

• SMTP (port 25)

• SSL (port 443)

• TELNET (port 23)

UDP ports include the following:

• DNS (port 53)

• RADIUS (port 1812)

• RADIUS-OLD (port 1645), which is used in some older RADIUS implementations instead of port

1812

NOTE

You can add either port 1812 or port 1645 to a given real or virtual server, but you cannot add both ports to the same server.

The keepalive health checks are disabled by default. To enable a keepalive health check for an application port, configure a port profile for the port (which automatically enables the keepalive globally for the port) or enable the keepalive on individual real servers that use the port.


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DNS

The Brocade Virtual ADX performs one or both of the following types of DNS health checks:

• Address-based – The Brocade Virtual ADX sends an address request for a specific domain name. If the server successfully responds with the IP address for the domain name, the server passes the health check.

• Zone-based – The Brocade Virtual ADX sends a Start-of-Authority (SOA) request for a specific zone name. If the server is authoritative for the zone and successfully responds to the SOA request, the server passes the health check.

NOTE

If you configure both types of DNS health check for a server, the server must successfully respond to both health checks to remain in the server rotation. You enable each type of DNS health check on a global basis and configure them on an individual server basis.

• If the server replies with the requested IP address or zone name, the Brocade Virtual ADX considers the server port to be ACTIVE and marks it as such.

• If the server does not reply with the requested IP address or zone name, the Brocade Virtual

ADX retries the health check up to the number of times configured (the default is two retries). If the server still does not send the requested information, the Brocade Virtual ADX marks the

DNS port on the server FAILED and removes the server from the rotation for DNS services.

NOTE

By default, the health check is non-recursive. If the real server (DNS server) does not successfully reply to the health check, then the DNS port fails the health check. You can enable the real server to perform a recursive lookup for the IP address or zone requested by the health check. In this case, if the real server does not have the requested address or zone, the server can pass the request on to a DNS server with higher authority. Refer to

“Enabling recursive DNS health checks” on page 179.

Performed:

• Immediately following a successful Layer 4 UDP health check

• At regular intervals, if keepalive is enabled for the port

Configuration

To perform a health check on a DNS port, use a configuration such as the following.

Example

Virtual ADX(config-port-dns)#show run | b 53 server port 53 udp keepalive 15 3 tcp keepalive disable server real rs1 10.2.2.200

port dns port dns keepalive port dns addr_query "www.brocade.com" server virtual-name-or-ip test 10.2.2.222

sticky-age 60 port dns


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!

end

NOTE

If the addr_query or zone has a “.” at the end, the Brocade Virtual ADX will return “invalid packet” for Layer 7 DNS health check.

FTP

The Brocade Virtual ADX waits for a message from the server:

• If the server sends a greeting message with status code 220, the Brocade Virtual ADX resets the connection and marks the port ACTIVE.

• If the server does not send a greeting message with status code 220, the Brocade Virtual ADX retries the health check up to the number of times configured (the default is two retries). If the server still does not send the expected message, the Brocade Virtual ADX marks the server port FAILED and removes the server from the load-balancing rotation for FTP service.

Performed:

• Immediately following a successful Layer 4 TCP health check


HTTP (status code)

The Brocade Virtual ADX sends HTTP GET or HEAD requests to HTTP servers when using SLB.

The GET or HEAD request specifies a page (identified by the URL, “Universal Resource Locator”) on the server. By default, the Brocade Virtual ADX sends a HEAD request for the default page, “1.0”.

• If the server responds with an acceptable status code, the Brocade Virtual ADX resets the connection and marks the port ACTIVE. For SLB, the default acceptable status codes for the check are 200 through 299 and 401.

• If the server responds with a different status code, the Brocade Virtual ADX marks the HTTP port FAILED.

• If the server does not respond, the Brocade Virtual ADX retries the health check up to the number of times configured (the default is two retries). If the server still does not respond, the

Brocade Virtual ADX marks the server port FAILED and removes the server from the load-balancing rotation for HTTP service.

NOTE

You can change the status code range for individual servers. If you do so, the defaults are removed and only the status code ranges you specify cause the server to pass the health check.

Performed:




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HTTP (content verification)

The Brocade Virtual ADX sends HTTP GET or HEAD requests to HTTP servers when using SLB.

The GET or HEAD request specifies a page (identified by the URL) on the server. The Brocade Virtual

ADX examines the page and compares the contents of the page to a list of user-defined selection criteria.

Based on the results of this comparison, the Brocade Virtual ADX takes one of the following actions with respect to port 80 (HTTP) on the real server:

• If the page meets the criteria for keeping the port up, then the Brocade Virtual ADX marks the port ACTIVE. This means that the HTTP application has passed the health check.

• If the page meets the criteria for bringing the port down, then the Brocade Virtual ADX marks the port FAILED.

• If the page meets none of the selection criteria, then the Brocade Virtual ADX marks the port either ACTIVE or FAILED according to a user-defined setting.

Refer to “Configuring HTTP content matching lists” on page 208 for information on specifying a

page to check and on setting up lists of selection criteria.

Performed:



Scripted (content verification for unknown ports)

After a successful Layer 4 health check, the Brocade Virtual ADX waits for the real server to send back a packet in response.

The Brocade Virtual ADX looks in the response packet for a user-specified ASCII string, defined in a matching list. The Brocade Virtual ADX compares the contents of the string to a list of user-defined selection criteria in the matching list.

Based on the results of this comparison, the Brocade Virtual ADX takes one of the following actions with respect to the port on the real server:

• If the text in the response meets the criteria for keeping the port up, then the Brocade Virtual

ADX marks the port ACTIVE.

• If the text in the response meets the criteria for bringing the port down, then the Brocade

Virtual ADX marks the port FAILED.

• If the text in the response meets none of the selection criteria, then the Brocade Virtual ADX marks the port either ACTIVE or FAILED according to a user-defined setting.

• If no response is received within the configured interval (the default is five seconds), the

Brocade Virtual ADX sends a RST and retries the health check. After the configured number of retries (the default is two retries), if the server still does not respond, the Brocade Virtual ADX marks the server port FAILED.

Refer to “Configuring scripted health checks” on page 211 for more information.

Performed:




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IMAP4

The Brocade Virtual ADX waits for a message from the IMAP4 server:

• If the server sends a greeting message that starts with “* OK”, The Brocade Virtual ADX sends a Logout command to the IMAP4 port on the real server, resets the connection, and marks the port ACTIVE.

• If the server does not send a greeting message that starts with “* OK”, the Brocade Virtual

ADX retries the health check up to the number of times configured (the default is two retries). If the server still does not send the expected message, the Brocade Virtual ADX marks the server port FAILED and removes the server from the load-balancing rotation for IMAP4 service.

Performed:



LDAP

The Brocade Virtual ADX supports both anonymous and authenticated bonding with LDAP servers.

With anonymous bonding, the Brocade Virtual ADX simply checks the format of the bind response and marks the LDAP port as active so long as the format of the bind response is correct.

Authenticated bonding requires both the configuration of a username and password for authentication and the configuration of a base Distinguished Name (DN) for searching the LDAP directory. With authenticated bonding, the Brocade Virtual ADX marks the LDAP port as active only after the completion of a successful authenticated bind and search operation.

Anonymous bonding

If a username and password are not configured, the Brocade Virtual ADX sends an anonymous bind request to the LDAP server and waits for a reply. The bind request includes a configurable version number, which can be 2 or 3. The default is 3.

• If the server sends a bind reply with a result code of any status (no error), the Brocade Virtual

ADX resets the connection and marks the port ACTIVE.

• If the server does not send a bind reply by the time the LDAP keepalive health check expires, the Brocade Virtual ADX retries the health check for a user-configured number of retries (the default is two). If the server still does not respond, the Brocade Virtual ADX marks the server port FAILED and removes the server from the load-balancing rotation for LDAP service.


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Authenticated bonding

If a username and password are configured, the Brocade Virtual ADX sends an authenticated bind request to the LDAP server that includes three configurable parameters: the version number, the name of the directory object that the client wants to bind to, and information used to authenticate the Distinguished Name (DN).

Brocade Virtual ADX then queries the LDAP directory using a user-configured search.

• If the server sends a bind reply with a result code of any status (no error), the Brocade Virtual

ADX resets the connection and marks the port ACTIVE.

• If the result of the query is any error value, the Brocade Virtual ADX marks the server port

DOWN and removes the server from the load-balancing rotation for LDAP service.

Performed:



Brocade Virtual ADX also supports server response threshold health checks for LDAP servers. To learn more see

“Server response threshold health check” on page 164.

MMS

The Brocade Virtual ADX sends an intentionally invalid request to the server:

• If the server replies with a packet containing the value "MMS", the Brocade Virtual ADX marks the port ACTIVE.

• If the server does not reply with a packet containing the value "MMS", the Brocade Virtual ADX retries the health check up to the number of times configured (the default is two retries). If the server still does not respond, the Brocade Virtual ADX marks the server port FAILED and removes the server from the load-balancing rotation for MMS service.

NOTE

You can view the Brocade Virtual ADX’s invalid request in the MMS server log. The log entry has error code 400.

Performed:




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NNTP

The Brocade Virtual ADX waits for a message from the NNTP server:

• If the server sends a greeting message with status code 200 or 201, the Brocade Virtual ADX sends a Quit command to the NNTP port on the real server, then resets the connection by sending a quit and a RESET, one immediately after the other, and marks the port ACTIVE.

• If the server does not send a greeting message with status code 200 or 201, the Brocade

Virtual ADX retries the health check up to the number of times configured (the default is two retries). If the server still does not send the expected message, the Brocade Virtual ADX marks the server port FAILED and removes the server from the load-balancing rotation for NNTP service.

Performed:



PNM

The Brocade Virtual ADX sends a PNM file request that does not have a file name:

• If the server sends a reply containing the value "PNA", the Brocade Virtual ADX marks the port

ACTIVE.

• If the server does not send a reply containing the value "PNA", the Brocade Virtual ADX retries the health check up to the number of times configured (the default is two retries). If the server still does not send the expected message, the Brocade Virtual ADX marks the server port

FAILED and removes the server from the load-balancing rotation for PNM service.

Performed:



POP3

The Brocade Virtual ADX waits for a message from the POP3 server:

• If the server sends a greeting message that starts with “+ OK”, the Brocade Virtual ADX sends a Quit command to the POP3 port on the real server, then resets the connection by sending a quit and a RESET, one immediately after the other, and marks the port ACTIVE

• If the server does not send a greeting message that starts with “+ OK”, the Brocade Virtual

ADX retries the health check up to the number of times configured (the default is two retries). If the server still does not send the expected message, the Brocade Virtual ADX marks the server port FAILED and removes the server from the load-balancing rotation for POP3 service.

Performed:




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RADIUS

The Brocade Virtual ADX sends an authentication request with a user name, password, and key to the RADIUS server. The account information does not need to be valid for the server to pass the health check. In fact, to prevent someone from learning account information by observing the

Brocade Virtual ADX RADIUS health check, Brocade recommends you use invalid information.

If the server replies with the result code “ACCEPT” or “REJECT” (or “ACCEPT only”, if required), the

Brocade Virtual ADX considers the port to be fine and marks it ACTIVE.

If the server does not reply or the server sends an ICMP “Destination Unreachable” message, the

Brocade Virtual ADX retries the health check up to the number of times configured (the default is two retries). If the server still does not reply with “ACCEPT” or ”REJECT” (or “ACCEPT only”), the

Brocade Virtual ADX marks the RADIUS port FAILED and removes the server from the rotation for

RADIUS services.

It is possible to distinguish between the result code of “ACCEPT” or “REJECT” to determine the health of the RADIUS server. For example, a “REJECT” is considered to indicate a health check fail condition. This can be done using the following CLI global command:

Virtual ADX(config)#server radius-fail-healthcheck-on-access-reject

NOTE

You can configure a health check either for the well-known RADIUS port number 1812 or port 1645.

You cannot configure a health check for both of these ports on the same server.

Performed:

• Immediately following a successful Layer 4 UDP health check


RTSP

The Brocade Virtual ADX sends a standard RTSP option packet, using sequence number 1:

• If the server responds with an acceptable status code, the Brocade Virtual ADX resets the connection and marks the port ACTIVE. For SLB, the default acceptable status codes for the check are 200–299 and 401.

• If the server responds with a different status code, the Brocade Virtual ADX marks the port

FAILED.


Brocade Virtual ADX marks the server port FAILED and removes the server from the load-balancing rotation for RTSP service.

Performed:




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SMTP

The Brocade Virtual ADX waits for a message from the SMTP server:

• If the server sends a greeting message with status code 220, the Brocade Virtual ADX sends a

Quit command to the SMTP port on the real server, then resets the connection by sending a quit and a RESET, one immediately after the other, and marks the port ACTIVE.

• If the server does not send a greeting message with status code 220, the Brocade Virtual ADX retries the health check up to the number of times configured (the default is two retries). If the server still does not send the expected message, the Brocade Virtual ADX marks the server port FAILED and removes the server from the load-balancing rotation for SMTP service.

Performed:



SSL (complete)

The Brocade Virtual ADX initiates an SSL connection with the server on TCP port 443, a secure link is negotiated, and encrypted data is transferred across it.

NOTE

SSL Layer 7 health check supports a maximum RSA key bit length of 4096. An RSA key bit length of

8192 is not supported.

After the SSL connection is established, the Brocade Virtual ADX sends the SSL server an HTTP

GET or HEAD request. The GET or HEAD request specifies a page containing the URL of a page on the server. By default, the Brocade Virtual ADX sends a HEAD request for the default page, “1.0”, although this can be changed with the port ssl url command:

• If the server responds with an acceptable status code, the Brocade Virtual ADX resets the connection and marks the port ACTIVE.


Brocade Virtual ADX marks the server port FAILED and removes the server from the load-balancing rotation for SSL service.

Performed:



It is possible to assign an HTTP content verification health check to the real server for the page returned by “port ssl url”. The Brocade Virtual ADX examines response by a real server. The

Brocade Virtual ADX searches the text in the HTML file for user-specified selection criteria and determines whether the SSL port on the real server is alive based on what it finds. The selection criteria used in HTTP content verification is contained in a matching list that is attached to one or more real servers.

NOTE

Reference the topic on “Using SSL health checks in a health check policy” on page 202 and the

“Content match for HTTP” on page 208 for more information.


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SSL (simple)

The Brocade Virtual ADX sends an SSL client hello with the SSL SID set to 0:

• If the server responds, then the Brocade Virtual ADX resets the connection and marks the port

ACTIVE.


Brocade Virtual ADX marks the server port FAILED and removes the server from the load-balancing rotation for SSL service.

Performed:



Telnet

The Brocade Virtual ADX waits for a message from the Telnet server:

• If the server sends a command string that starts with the IAC escape characters (“FF”), the

Brocade Virtual ADX resets the connection and marks the port ACTIVE.

• If the server does not send a command that starts with the IAC escape character, the Brocade

Virtual ADX retries the health check up to the number of times configured (the default is two retries). If the server still does not send the expected escape character, the Brocade Virtual

ADX marks the server port FAILED and removes the server from the load-balancing rotation for

Telnet service.

Performed:



Port-specific settings for Layer 7 health checks

You can configure the following Layer 7 health check parameters on a real server basis:

• Keepalive health check state (enabled or disabled)

• HTTP keepalive method, values, and valid status codes

• HTTP content matching lists for HTTP content verification health checks

• Scripted health checks (content verification health checks for unknown ports)

• DNS keepalive method and values (zone-based or addressed-based check and the zone or domain name)

• RADIUS keepalive values (user name, password, and encryption key)

• LDAP version (2 or 3)


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NOTE

The Brocade Virtual ADX uses its own management IP address or a source IP address configured on the Brocade Virtual ADX as the source IP address in the health check packets (as opposed to a virtual IP address). If the real servers are in the same subnet as the Brocade Virtual ADX, then the health checks can use the Brocade Virtual ADX’s management IP address. Otherwise, the health checks use a source IP address.

Enabling Layer 7 health check

All Layer 7 health checks are disabled by default. You can enable a health check globally or locally.

NOTE

The Brocade Virtual ADX considers a Layer 7 health check to be disabled only if the health check is disabled on both the global and local levels. If the health check is enabled globally, locally, or both,

the Brocade Virtual ADX considers the health check to be enabled. Refer to “Configuring a port profile” on page 188.

To locally enable a Layer 7 health check, enter a command such as the following at the real server level of the CLI.

Virtual ADX(config-rs-jet)#port http keepalive

Syntax: [no] port port keepalive

If you use the no port command, you are locally disabling the health check. The health checks are locally disabled by default.

The port variable is the port name or number. Enter one of the following values. If the port is not one of the following well-known port, specify the port number.

• dns (port 53)

• ftp (port 21). Ports 20 and 21 both are FTP ports but in the Brocade Virtual ADX, the name

“ftp” corresponds to port 21.

• http (port 80)

• imap4 (port 143)

• ldap (port 389)

• nntp (port 119)

• ntp (port 123)

• pop2 (port 109)

• pop3 (port 110)

• radius (UDP port 1812)

• radius-old (UDP port 1645, which is used in some older RADIUS implementations instead of port 1812)

• smtp (port 25)

• snmp (port 161)

• ssl (port 443)

• telnet (port 23)

• tftp (port 69)

• number


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HTTP

Changing HTTP keepalive method, value, and status codes

The Brocade Virtual ADX supports two kinds of HTTP health checks:

• HTTP status code health checks look at the status code returned in HTTP responses to keepalive requests.

• HTTP content verification health checks look at the actual HTML contained in HTTP responses to keepalive requests.

The default URL page for HTTP keepalive requests used in HTTP health checks is “HEAD /1.0”. You can change the URL that the Brocade Virtual ADX requests on a real server basis.

NOTE

For HTTP content verification health checks, you might want to change the default URL page for HTTP keepalive requests URL page, since a request for “HEAD /1.0” would not return a response containing HTML for content verification. You can specify a GET request for a page containing text

that can be searched and verified. Refer to “Configuring HTTP content matching lists” on page 208

for more information.

To configure the HTTP keepalive request to send a GET request for “sales.html”, enter the following commands.

Virtual ADX(config)#server real zip 10.96.3.251

Virtual ADX(config-rs-zip)#port http url "GET /sales.html"

Virtual ADX(config-rs-zip)#exit

Virtual ADX(config)#server virtual-name-or-ip shoosh 10.96.4.250

Virtual ADX(config-vs-shoosh)#port http

Virtual ADX(config-vs-shoosh)#bind http zip http

Virtual ADX(config-vs-shoosh)#exit

Syntax: port http url “[GET | HEAD] [/] URL-page-name ”

GET or HEAD is an optional parameter that specifies the request type. By default, HTTP keepalive uses HEAD to retrieve the URL page. You can override the default and configure the Brocade Virtual

ADX to use GET to retrieve the URL page.

The slash (/) is an optional parameter. If you do not set the GET or HEAD parameter, and the slash is not in the configured URL page, then Brocade Virtual ADX automatically inserts a slash before retrieving the URL page.

To change the HTTP status codes that the Brocade Virtual ADX considers normal (not indicative of a failure of the HTTP service), enter the following command.

Virtual ADX(config-rs-zip)#port http status-code 200 201 300 302

Syntax: port http status-code range [ range [ range [ range ]]]

The command in the example specifies two ranges (200–201 and 300–302). You can specify up to four ranges (total of eight values). To specify a single message code for a range, enter the code twice. For example to specify 200 only, enter the port http status-code 200 200 command.

NOTE

When you change the status code ranges, the defaults are removed. As a result, you must specify all the valid ranges, even if a range also is within the default ranges. For example, if you still want codes 200 to 299 to be valid, you must specify them.


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DNS

Enabling recursive DNS health checks

By default, a Layer 7 health check for a DNS port sends the query only to the real server (DNS server). If the DNS server does not reply with the IP address or zone name requested by the health check, the port fails the health check.

You can enable the real server to perform a recursive lookup for the IP address or zone requested by the health check. In this case, if the real server does not have the requested address or zone, the server can pass the request on to a DNS server with higher authority. The real server can repeat this process until either a DNS server with higher authority successfully replies to the health check, or the server with the highest authority is unable to successfully reply to the request.

To enable recursive DNS health checks globally at the port profile level for the DNS port, enter commands such as the following.


Virtual ADX(config-port-dns)#allow-recursive-search

Syntax: [no] allow-recursive-search

NOTE

This feature applies to Boolean health checks in addition to standard (non-Boolean) health checks.

NOTE

You can enable this feature only on the well-known DNS port (53).

Configuring DNS health check method and values

The keepalive time and number of retries are global parameters. However, you configure the DNS health checking methods and values on an individual server basis. You can set the following types of DNS health checks (none configured by default):

• Address-based – The Brocade Virtual ADX sends an address request for a specific domain name. If the server successfully responds with the IP address for the domain name, the server passes the health check.

• Zone-based – The Brocade Virtual ADX sends a Start-of-Authority (SOA) request for a specific zone name. If the server is authoritative for the zone and successfully responds to the SOA request, the server passes the health check.

To configure the domain name for address-based DNS health checking, enter the following command.

Virtual ADX(config-rs-zip)#port dns addr_query "example2.com"

Syntax: [no] port dns addr_query " name "

To configure the zone name for zone-based DNS health checking, enter the following command.

Virtual ADX(config-rs-zip)#port dns zone example2.com

Syntax: [no] port dns zone zone-name


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RADIUS

Configuring RADIUS health check values

You can define the RADIUS parameters that the Brocade Virtual ADX sends to a RADIUS application port during the Layer 7 health check.

The RADIUS health check requires a specific user name, password, and authentication key from the RADIUS server. To specify these values, use one of the following methods.

To configure the parameters for a RADIUS health check, enter commands such as the following at the real server level of the CLI.

Virtual ADX(config-rs-rocket)#port radius username evil

Virtual ADX(config-rs-rocket)#port radius password woody

Virtual ADX(config-rs-rocket)#port radius key laser

Syntax: [no] port radius username string

Syntax: [no] port radius password string

Syntax: [no] port radius key string

Dropping failed RADIUS health checks

With a valid response from a RADIUS server (that is, user authentication pass or fail), the Brocade

Virtual ADX marks the RADIUS health check as passed. However, this behavior might not be desired in some cases. The following enhancement lets the Brocade Virtual ADX mark the RADIUS health check as FAIL if authentication is received as (PW_ACCESS_REJECT).

Virtual ADX(config-rs-rocket)#server radius-fail-healthcheck-on-access-reject

Syntax: [no] server radius-fail-healthcheck-on-access-reject

LDAP

Configuring Usernames for Authenticated LDAP Bonding

Authenticated bonding with an LDAP server requires the configuration of a username and password that are sent as parameters in the bind request.

To define the username the Brocade Virtual ADX will use to create an authenticated bind with an

LDAP port on a real server, enter commands such as the following at the real port level of the CLI.


Virtual ADX(config-rs-r1)#port ldap username “cn=Directory Manager”

Syntax: [no] port {ldap | ldaps | port-num } username name

The name variable specifies the name of the Directory object that the Brocade Virtual ADX will bind as; it is a character string that cannot exceed 128 characters.

Configuring Passwords for Authenticated LDAP Bonding

To define the password the Brocade Virtual ADX will use to create an authenticated bind with an

LDAP port on a real server, enter commands such as the following at the real port level of the CLI.


Virtual ADX(config-rs-r1)#port ldap password “brocade123”


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Syntax: [no] port {ldap | ldaps | port-num } password string

The string variable specifies the password for the Directory object that the Brocade Virtual ADX binds as; it is a character string that cannot exceed 64 characters.

Configuring Base Distinguished Names for Authenticated LDAP Bonding

To configure the base Distinguished Name (DN) used to query the LDAP directory, enter commands such as the following at the real port level of the CLI.


Virtual ADX(config-rs-r1)#port ldap search-base-dn “ou=groups,dc=brocade,dc=com”

Syntax: [no] port {ldap | ldaps} search-base-dn distinguished-name

The distinguished-name is a character string that cannot exceed 256 characters.

LDAP over SSL

The Brocade Virtual ADX can perform LDAP health checks using a Secure Sockets Layer (SSL) connection on TCP port 636.

The LDAP over SSL (LDAPS) health check procedure works as follows:

The Brocade Virtual ADX initiates an SSL connection with the server on TCP port 636, a secure link is negotiated, and encrypted data is transferred across the link. After the SSL connection is established, the Brocade Virtual ADX sends a bind request to the LDAPS server and waits for a reply. The bind request includes a configurable version number, either 2 or 3 (by default, version 3).

• If the LDAPS server sends a bind reply with a result code of any status (no error), the Brocade

Virtual ADX resets the connection and marks the port ACTIVE.

• If the LDAPS server does not send a bind reply by the time the LDAPS keepalive interval expires, the Brocade Virtual ADX retries the health check up to the number of times configured

(by default, two retries). If the LDAPS server still does not respond, the Brocade Virtual ADX marks the server port FAILED and removes the LDAPS server from the load-balancing rotation for LDAPS service.

You can configure standard (non-Boolean) LDAPS health checks. Health checking commands available for other TCP ports are also available for the LDAPS port.

Configuring Non-boolean LDAP health checks

To configure a standard health check for the port ldaps command on real server r1, enter the following commands.

Virtual ADX(config)#server port ldaps

Virtual ADX(config-port-ldaps)#tcp keepalive enable

Virtual ADX(config-port-ldaps)#exit


Virtual ADX(config-rs-r1)#port ldaps


If the no-fast-bringup command is not configured for the LDAPS port, if the l4-check-only command is configured for the LDAPS port, or if the keepalive health check for the LDAPS port is disabled, the

Brocade Virtual ADX does not establish a secure connection when performing a health check on port 636. Instead, the Brocade Virtual ADX establishes a regular TCP connection on port 636 and sends a TCP RESET, using the same method as the LDAP health check.


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Configuring Boolean LDAP health checks

To configure a Boolean LDAPS health check, enter commands such as the following.

Virtual ADX(config)#healthck check1 tcp

Virtual ADX(config-hc-check1)#dest-ip 10.10.1.101

Virtual ADX(config-hc-check1)#port ldaps

Virtual ADX(config-hc-check1)#protocol ldaps

Virtual ADX(config-hc-check1)#l7-check

A Layer 7 health check must be configured in order for the Brocade Virtual ADX to establish a secure connection on the LDAPS port. If only a Layer 4 health check is configured, then the

Brocade Virtual ADX establishes a regular TCP connection on port 636.

Simple and compound SSL health checks

The Brocade Virtual ADX supports two kinds of SSL health checking methods:

• The Simple method sends the server an SSL client hello with the SSL SID set to 0. If the server responds, then the server passes the health check. The Brocade Virtual ADX then resets the connection and marks the SSL port ACTIVE.

• The Compound method negotiates an SSL connection and sending a GET or HEAD request to the server once the connection is established. The GET or HEAD request specifies a page containing the URL of a page on the server. If the server responds with an acceptable status code, the Brocade Virtual ADX resets the connection and marks the port ACTIVE.

Configuring SSL health checks

To configure the Brocade Virtual ADX to use the simple SSL health check, enter the following command.

Virtual ADX(config)#server use-simple-ssl-health-check

To use the complete SSL health check, enter the no server use-simple-ssl-health-check command.

Virtual ADX(config)#no server use-simple-ssl-health-check

NOTE

When you configure complete SSL health check on the Brocade Virtual ADX and the server response is in small TCP segment packets of 5 to 50 bytes, flapping occurs and the Brocade Virtual ADX displays the following error messages:

SSL interface: ssl_read_data return error !!!

SSL read data: can't find key ???

Syntax: [no] server use-simple-ssl-health-check

Error messages

The following error messages are related to SSL health check, after receiving SSL data while it cannot find the key to decrypt the data. The key is missing possibly due to a time out.

ssl_receive_data but tcb->ssl is null

SSL cleanup: can't find key ???





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The Brocade Virtual ADX normally stops processing the rest of the data and releases the SSL control block data structure. However when the Brocade Virtual ADX does not do that, the Brocade

Virtual ADX finds the SSL data structure is null and prints these messages.

Layer 7 health check for an unknown port

You can use Layer 7 health check parameters for the following known ports to check the health of unknown ports:

• TCP ports:

• HTTP (port 80)

• FTP (port 21)


• LDAP (port 389)

• POP3 (port 110)

• SMTP (port 25)

• Telnet (port 23)

• UDP ports:

• DNS (port 53)

Configuring an unknown TCP port to use Layer 7 TCP health checks

You can use the Brocade Virtual ADX’s Layer 7 health check mechanism for the following TCP applications on any TCP port number:

• HTTP (port 80)

• FTP (port 21)


• LDAP (port 389)

• POP3 (port 110)

• SMTP (port 25)

• Telnet (port 23)

The health check mechanisms for these ports are described in “Health checks overview” on page 159.

To configure an unknown TCP port to use the Layer 7 health check for one of the applications listed above, enter commands such as the following.


Virtual ADX(config-port-999)#tcp keepalive protocol smtp

These commands configure port profile parameters for port 999. The second command in the example makes the port a TCP port and assigns the SMTP Layer 7 health check to the port.

Syntax: [no] server port TCP-portnum


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Server and application port states

Syntax: [no] tcp keepalive protocol TCP-port

The protocol TCP-port parameters specify the type of Layer 7 health you want to use for the port.

You can specify one of the following:

• ftp or 21

• imap4 or 143

• ldap or 389

• pop3 or 110

• smtp or 25

• telnet or 23

Configuring an unknown UDP port to use a Layer 7 health check

The Brocade Virtual ADX can perform Layer 7 health checks on the DNS port (UDP port 53).

To configure an unknown UDP port to use the DNS Layer 7 health check:

• Configure the Layer 7 health check on the DNS port (53). For configuration information, refer to

“Configuring DNS health check method and values” on page 179. The unknown port uses the

same health check parameters as the ones you configure for the DNS port. For example, if you configure an address-based DNS health check for a specific domain name, the Brocade Virtual

ADX requests the same domain name when checking the health of the unknown port.

• Create a port profile for the unknown port and specify dns or 53 as the well-known port whose

Layer 7 health check you want to use.

To configure an unknown port to use a Layer 7 health check, enter commands such as the following.


Virtual ADX(config-port-999)#udp keepalive protocol dns

Syntax: server port UDP-portnum

Syntax: udp keepalive protocol UDP-portnum

The protocol UDP-port parameters specify the type of Layer 7 health you want to use for the port.

You can specify dns or 53.


Server states

The server states only concern up to Layer 3. They do not deal with Layers 4 or Layer 7. In Table 15 ,

Layer 2 reachability refers to ARPs, a Layer 2 query for Layer 3 information. Layer 3 reachability refers to ICMP echo requests and replies, or pings.

NOTE

Layer 4 refers to making a TCP connection to a port. Layer 7 refers to making an HTTP request and getting an HTTP reply.


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TABLE 15 Server states

State Description

ENB:enabled

FAL:failed

TST:testing

SUS:suspect

GDN:grace-dn

ACT:active

There is no link to the real server. The real server is configured on the Brocade Virtual ADX but is not physically connected to the Brocade Virtual ADX.

The real server has failed to respond to repeated Layer 3 health checks (IP pings). Typically, a real server changes to the FAILED state from the SUSPECT state.

A real server will go to "Testing" if it is reachable at Layer 2 but not at Layer 3. When you first add a real server, the Brocade Virtual ADX will first try to ARP it. While it is ARPing, the server state will read "State: Enabled". After the real server replies to the ARP, the Brocade Virtual

ADX will normally send one ICMP echo request. After it gets the ARP reply and before it gets the ICMP echo reply, the Brocade Virtual ADX will show the real server state as Testing. If you have a firewall application on the real server so that it responds to ARP queries but not to

ICMP pings, then the real server will show as "Testing" indefinitely.

Use the show server real command to display detailed state information. The show server bind command is more concise, though it focuses on port status.

The Brocade Virtual ADX associates a time stamp with each packet sent to and received from the real servers. If the time gap between the last packet received from the server and the last packet sent to the server grows to 3 or 4 seconds, the Brocade Virtual ADX sends a ping

(Layer 3 health check) to the server. If the server does not respond within the ping interval (a configurable parameter), the Brocade Virtual ADX changes the state to SUSPECT and resends the ping, up to the number of retries specified by the ping retries parameter (also configurable). If the server still does not respond after all the retries, the state changes to

FAILED. If the server does respond, the state changes to ACTIVE.

The server gracefully shut down. Refer to server force-delete command under the “Enabling force-delete” section.

A real server will go to active as long as it is reachable at Layer 2 and Layer 3, regardless of whether its ports are bound to anything, or whether its ports pass tests.

UNB:unbind

AWU:await-unbind

AWD: await-shutdown

Used for ports that have not been bound to a virtual server.

Both can occur when you're trying to unbind or delete ports. You might not even see them in anything but a live environment. After you remove real servers from a virtual server or delete virtual servers or unbind ports, normally the Brocade Virtual ADX or stackable waits until connections in progress finish their business.

Application port states

Table 16

lists the application port states.

TABLE 16 Application port states

State Description

ENABLED

FAILED

TEST

There is no link to the server. The server is configured on the Brocade Virtual ADX but is not connected to the Brocade Virtual ADX. (This is the same as the ENABLED server state.)

The application has failed to respond to repeated Layer 4 or (if applicable) Layer 7 health checks.

Typically, an application changes to the FAILED state from the SUSPECT state. Note that if a application does not pass the Layer 4 health check, the Brocade Virtual ADX does not waste resources on the Layer 7 health check, because the application clearly is not available. When an application enters the FAILED state, the state of the real server itself moves to the TEST state while the Brocade Virtual ADX continually tries to reach the failed application.

The server is still reachable at Layer 3, but the application has failed to respond to its Layer 4 (or if applicable, Layer 7) health check.


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TABLE 16 Application port states (Continued)

State Description

SUSPECT

GRACE_DN

ACTIVE

UNBND

The Brocade Virtual ADX associates a time stamp with each packet sent to and received from the real servers. If the time gap between the last packet received from the server and the last packet sent to the server grows to 3 or 4 seconds, the Brocade Virtual ADX sends a Layer 4 health check to the service. (If applicable, and if the server passes the Layer 4 health check, the Brocade

Virtual ADX then sends a Layer 7 health check to the application.) If the application does not respond within a specified interval, the Brocade Virtual ADX changes the state to SUSPECT and resends the Layer 4 (and if applicable, Layer 7) health check up to a specific number of retries. If the application still does not respond after all the retries, the state changes to FAILED and the server state changes to TEST. If the application does respond, the application state changes to

ACTIVE.

The forced-shutdown option has been used to gracefully shut the server down.

The application has passed its Layer 4 (and if applicable, Layer 7) health check.

The application is configured on the real server but is not yet bound to a virtual server.

Displaying real server state information

To display real server information, enter the following command at any level of the CLI.

Virtual ADX(config)#show server real

Real Servers Info

========================

State - ACT:active, ENB:enabled, FAL:failed, TST:test, SUS:suspect,

GDN:grace-dn, DIS:disabled, UNK:unknown, UNB:unbind,

AWU:await-unbind, AWD: await-shutdown

Name: rs1

Mac: Unknown

SrcNAT: not-cfg, not-op

State: Enabled IP:10.95.7.1: 1

Weight: 1/1 MaxConn: n/a

DstNAT: not-cfg, not-op Serv-Rsts: 0


---- -- -- ------- ------- ------- ------- -------- -------- ---default UNB 0 0 0 0 0 0 0 0 http ENB 0 0 0 0 0 0 0 0


Information about the remaining real servers has been omitted for brevity.

Syntax: show server real

The state information lists the state of the server itself first. Then the states of each of the application ports configured on the server are displayed.

In this example, the server itself is enabled. The HTTP port is also enabled, but the “default” port (a port the Brocade Virtual ADX automatically configures on all the real and virtual servers) is unbound (unbnd). These states are typical of a Brocade Virtual ADX that is configured for deployment but has not been connected to the real servers.

If information appears under the row for the HTTP application, it shows settings for the Layer 7 health checks for the port. For information about HTTP health checks and other configurable Layer

7 health check parameters, refer to “Port-specific settings for Layer 7 health checks” on page 176.


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Displaying virtual server state information

To display virtual server information, enter the following command at any level of the CLI.

Virtual ADX(config)#show server virtual

Virtual Servers Info

Name: v100 State: Enabled IF DWN IP:10.157.23.100 : 4

Pred: round-robin ACL-Id: 0 TotalConn: 0

VIP state: Healthy

Rx pkts: 0 Tx pkts: 0

Rx bytes: 0 Tx bytes: 0

Rx PPS: 0 Tx PPS: 0

Rx Throughput: 0 Kbps Tx Throughput: 0 Kbps tcp-conn-rate: 0 udp-conn-rate: 0

CPS: 0 CurrConn: 0

Note: The above statistics lag by 1 second

Port State Sticky Concur Proxy DSR CurConn TotConn PeakConn

---- ----- ------ ------ ----- --- ------- ------- -------default enabled NO NO NO NO 0 0 0 http enabled NO NO NO NO 0 0 0

Port Rx-pkts Tx-pkts Rx-octet Tx-octet

---- ------- ------- -------- -------default 0 0 0 0 http 0 0 0 0

Information about the remaining virtual servers has been omitted for brevity.

Syntax: show server virtual

In this example, the virtual server and the application ports configured on the server are enabled, indicating that the server and the application ports are configured on the Brocade Virtual ADX but the Brocade Virtual ADX is not connected to the real servers bound to this virtual server. Refer to

“Displaying real server state information” on page 186 for descriptions of the server and

application states.


A port profile is a set of attributes that globally defines an application port. Once defined, the port has the same attributes on all the real and virtual servers that use the port. Port profiles are useful if you want to globally change the attributes of a port known to the Brocade Virtual ADX (refer to the

list in “Port-specific settings for Layer 7 health checks” on page 176) or you want to globally define

a port that is not known to the Brocade Virtual ADX. You also can specify or change port attributes locally, on the real server and virtual server configuration levels.

If you want to enable the keepalive health check for an application port, you must configure a port profile for the port.


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Configuring a port profile

For an application port not known to the Brocade Virtual ADX, the Brocade Virtual ADX assumes that it is a UDP port. In addition, the Brocade Virtual ADX does not perform keepalive health checks for it. You can configure a port profile for the port and specify whether the port is TCP or UDP, in addition to setting keepalive health check parameters for the port.

Even for ports known to the Brocade Virtual ADX, you must configure a profile for the port to globally configure the port parameters and to configure the keepalive health check. After you add the port by indicating whether it is a TCP or UDP port, the Brocade Virtual ADX automatically enables the keepalive health check for the port.

NOTE

Enabling or disabling a keepalive health check does not affect the health check the Brocade Virtual

ADX sends when you bind a real server to a virtual server using the application port. The keepalive health check state also does not affect the health checks the Brocade Virtual ADX sends if the server’s response time slows.

The keepalive interval and retry values for each type of TCP/UDP health check are global parameters. For example, if you change the number of retries for the HTTP health check (TCP port

80), the change applies to all instances of port 80 on all the real servers configured on the Brocade

Virtual ADX.

TABLE 17 Keepalive health check states

State

Local (specific real server) Global (entire Brocade

Virtual ADX)

Disabled

Disabled

Enabled

Enabled

Disabled

Enabled

Disabled

Enabled

Effect

Health check is disabled

Health check is enabled



As shown in the

Table 17 , after a keepalive health check is enabled, to disable it you must do so

both globally and locally. If you want to enable keepalive health checks only on specific real servers

(locally), you can easily do so by making sure the health checks are disabled globally, then enabling them on individual real servers.

To enable or disable a keepalive health check globally, use one of the following methods. To enable or disable a keepalive health check locally, refer to

“Enabling Layer 7 health check” on page 177.

NOTE

DNS, HTTP, and RADIUS health checks use additional parameters, which you can configure using separate commands. Refer to

“Changing HTTP keepalive method, value, and status codes” on

page 178, “Configuring DNS health check method and values”

on page 179, or “Configuring RADIUS health check values” on page 180.

NOTE

When health checks are enabled for the ports on the VIPs in a host range, the Brocade Virtual ADX checks the health of the applications on the base IP address only. The Brocade Virtual ADX assumes that the health of an application is the same for all the VIPs within the host range.


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Adding a port and specifying its type

By adding a port, you also automatically enable periodic Layer 4 (and Layer 7, if applicable) keepalive health checks for the port. If you do not specify the port type (TCP or UDP), the Brocade

Virtual ADX assumes the port type is UDP.

To add a port and specify that it is a TCP port, enter commands such as the following.


Virtual ADX(config-port-8080)#tcp

Syntax: server port TCP/UDP-portnum

Syntax: tcp | udp [keepalive [disable | enable]]

Changing a port’s keepalive parameters

To change a port’s keepalive state, enter a command such as the following.

Virtual ADX(config-port-8080)#tcp keepalive disable

To change a port’s keepalive interval and retries, enter a command such as the following.

Virtual ADX(config-port-80)#tcp keepalive 15 5

Syntax: tcp | udp keepalive [ interval-in-seconds retries ]

You can specify from 1 through 120 seconds for the interval-in-seconds variable. You can specify from 1 through 5 for the retries variable.

Configuring port profile attributes

Table 18 lists the port attributes you can configure at the port profile level.

TABLE 18 Port profile attributes

Attribute Description

Port type (TCP or

UDP)

Keepalive interval and retries

Keepalive state

This attribute applies only to ports for which the Brocade Virtual ADX does not already know the type. For example, if a real server uses port 8080 for HTTP (a TCP port), you can globally identify 8080 as a TCP port. The Brocade Virtual ADX assumes that ports for which it does not know the type are UDP ports.

Refer to

“Adding a port and specifying its type” on page 189.

NOTE: To display a list of the ports for which the Brocade Virtual ADX already knows the type, enter the server port ? command at the global CONFIG level.

The number of seconds between health checks and the number of times the Brocade

Virtual ADX re-attempts a health check to which the server does not respond.

Refer to

“Changing a port’s keepalive parameters” on page 189.

Whether the Brocade Virtual ADX’s health check for the port is enabled or disabled.

Recurring Layer 4 and Layer 7 health checks are disabled by default. When you configure a port profile, the software automatically globally enables the health check for the application. You also can explicitly disable or re-enable the keepalive health check at this level.

NOTE: If you are configuring a port profile for a port that is known to the Brocade Virtual

ADX, the keepalive parameters affect Layer 7 health checks. For other ports, the keepalive parameters affect Layer 4 health checks.


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TABLE 18 Port profile attributes (Continued)

Attribute Description

Keepalive port

Source of health for alias port

By default, the Brocade Virtual ADX bases the health of an application port on the port itself. You can specify a different application port for the health check. In this case, the

Brocade Virtual ADX bases the health of an application port on the health of the other port you specify.

Refer to

“Basing a port’s health on the health of another port” on page 220.

NOTE: You cannot base the health of a port well-known to the Brocade Virtual ADX on the health of another port, whether the port is well-known or not well-known.

By default, the Brocade Virtual ADX performs independent health checks on an alias port and its master port. You can configure the Brocade Virtual ADX to base the health of an alias port on the state of its master port.

Refer to

“Basing an alias port’s health on the health of its master port” on page 219.

TCP or UDP age

Connection logging You can enable logging for session table entries created for this port.

Refer to

“Syslog for session table entries” on page 240.

Slow start Configures the Brocade Virtual ADX to control the rate of new connections to the application port to allow the server to ramp up.

Refer to

“Port slow-start mechanism” on page 227.

Smooth factor

The number of minutes a TCP or UDP session table entry can remain inactive before the

Brocade Virtual ADX times out the entry. This parameter is set globally for all TCP or UDP ports but you can override the global setting for an individual port by changing that port’s profile.

Refer to

“Overriding the global TCP or UDP age” on page 192.

You can specify a TCP age from 2 through 60 minutes and a multiplier from 2 through 20.

Thus, the maximum configurable TCP age for an individual port is 1200 minutes (20 hours).

NOTE: You cannot specify a multiplier when configuring the global TCP age.

NOTE: Because UDP is a connectionless protocol, the Brocade Virtual ADX does not remove a UDP session from its session table until the session times out. TCP is a connection-based protocol. Therefore, for TCP sessions, the Brocade Virtual ADX removes the session as soon as the client or server closes the session.

NOTE: For DNS and RADIUS UDP load balancing, the age value does not follow the normal configuration and default value unless udp-normal-age is configured on the port.

The default UDP age will always be 2 minutes unless udp-normal-age is configured.

NOTE: The Brocade Virtual ADX immediately deletes a UDP DNS or RADIUS session table entry when the Brocade Virtual ADX receives a reply for the application from a real server. If desired, you can configure the Brocade Virtual ADX to age these ports like other UDP ports, using the UDP age timer. Refer to

“Setting TCP and UDP ages for

VIPs” on page 121.

Recursive DNS health checks

If you plan to use server response time as a load-balancing method, you can adjust the amount of preference the Brocade Virtual ADX gives the most recent response time compared to the previous response time.

Refer to

“Changing the smooth factor on an application port” on page 192.

By default, a Layer 7 health check for a DNS port sends the query only to the real server

(DNS server). If the DNS server does not reply with the IP address or zone name requested by the health check, the port fails the health check.

You can enable the real server to perform a recursive lookup for the IP address or zone requested by the health check of the well-known DNS port (53).

Refer to

“Enabling recursive DNS health checks” on page 179.


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You also can change port attributes locally, on the real server and virtual server configuration levels. Port profiles simplify configuration by letting you characterize a port globally. For example, if many of your real servers use TCP port 80 (the well-known number for HTTP) and you want to change the keepalive interval for the port, you can do so globally. You do not need to change the value multiple times on each real server.

The Brocade Virtual ADX knows the port types of some well-known port numbers. If you are using a port number for which the Brocade Virtual ADX does not know the port type, you can specify whether the port is TCP or UDP and configure its keepalive values globally. You do not need to define the port on every server.

NOTE

Unless a port is known to the Brocade Virtual ADX to be a TCP port, the Brocade Virtual ADX assumes the port is UDP. If you are using a port number that is not known to the Brocade Virtual ADX and the port type is TCP, you must specify this either globally (using a port profile) or locally (when configuring the individual real servers and virtual servers). Otherwise, the Brocade Virtual ADX will use a UDP health check to test the port and the port will fail the health check.

NOTE

If you bind an application port on a real server to the same port on a virtual server, the port on the real server inherits the attributes of the port on the virtual server.

Displaying the session age of a TCP port

To display the session age of a TCP port, enter a command such as the following. The TCP session ages are shown in bold type. Notice that the TCP session ages for ports 8082 and HTTP (80) use multipliers.

Virtual ADX(config)#show server real rs1 detail

Real Servers Info

Name : rs1 Mac-addr: 0003.47bf.bad2

IP:192.168.6.91 Range:1 State:Active Max-conn: n/a

Least-con Wt:0 Resp-time Wt:0

Src-nat (cfg:op):(off:off) Dest-nat (cfg:op):(off:off)

Remote server : No Dynamic : No Server-resets:0

Mem:server: 02057999 Mem:mac: 02037cb0

Port State Ms CurConn TotConn Rx-pkts Tx-pkts Rx-octet Tx-octet Reas

---- ----- -- ------- ------- ------- ------- -------- -------- ---http failed 0 0 0 0 0 0 0 0

max_conn = 1 sessions = 0

Keepalive(G/L:On/Off):On

Status Code(s): default (200-299, 401)

HTTP URL: "HEAD /"

tcp-age: 60 * 2 default unbnd 0 0 0 0 0 0 0 0

max_conn = 0 sessions = 0

Server Total 0 0 0

Syntax: show server real name detail

0 0 0 0 0


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Overriding the global TCP or UDP age

The TCP and UDP ages specify how many minutes a TCP or UDP session can remain inactive before the Brocade Virtual ADX closes the session and clears it from its session table. You can set the TCP or UDP age from 2 through 60 minutes. The default TCP age is 30 minutes, and the default UDP age is 5 minutes.

Because UDP is a connectionless protocol, the Brocade Virtual ADX does not remove a UDP session from its session table until the session times out. On the other hand TCP is a connection-based protocol, so for TCP sessions, the Brocade Virtual ADX removes the session as soon as the client or server closes the session.

NOTE

The Brocade Virtual ADX immediately deletes a UDP DNS or RADIUS session table entry when the

Brocade Virtual ADX receives a reply for the application from a real server. If desired, you can configure the Brocade Virtual ADX to age these ports like other UDP ports, using the UDP age timer.

Refer to “Enabling normal UDP aging for DNS and RADIUS” on page 121.

For DNS and RADIUS UDP load balancing, the age value does not follow the normal configuration and default value unless the udp-normal-age option is configured on the port. The default UDP age will always be 2 minutes unless the udp-normal-age option is configured.

To change the global default for all TCP or UDP ports, refer to “Configuring TCP age” on page 239 or

“Configuring UDP age” on page 239.

To override the default TCP age and set the age for TCP port 80 to 15 minutes, enter the following commands.


Virtual ADX(config-port-80)#tcp 15


Syntax: tcp | udp age

The default TCP age is 30 minutes. The default UDP age is 5 minutes.

NOTE

The session age is per minute and has a one minute range. For example, if you configured a TCP or

UDP age of three minutes, the age timeout is from two to three minutes.

Changing the smooth factor on an application port

This smooth factor applies to ports that you plan to use with the server response time load-balancing metric. Refer to

“Changing the Load-Balancing Predictor Method” on page 21 and

“Configuring a stateless port” on page 30 for information about the server response time metric

and how the smooth time works.

The Brocade Virtual ADX calculates the server response time value for a real server by regularly collecting response time samples, then using a calculation to smooth the values of the samples and derive a single response time value for the real server. The Brocade Virtual ADX collects the samples around once every 100 milliseconds (about 10 times a second). The sampling rate can vary slightly depending on the processing the Brocade Virtual ADX is performing.


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To change the smooth factor for an application port, enter a command such as the following.

Virtual ADX(config-port-80)#smooth-factor 50

Syntax: smooth-factor num

Port policy

Port policies

Server port policies help reduce the configuration required for health checks and provide more flexibility while configuring health checks. Brocade Virtual ADX allows the use of Layer 7 health check parameters for known ports, such as HTTP, LDAP, SMTP, IMP4, POP3, NNTP, Telnet, FTP, SSL,

RTSP, MMS, PNM, and LDAPS to check the health of unknown ports. The configuration of server port policies consists of two parts:

•

Configuring a port policy

•

Binding the policy

Configuring a port policy

Follow the steps given below to configure a port policy.

1. First create a policy by entering a command such as the following.

Virtual ADX(config)#server port-policy p1

Syntax: server port-policy policy-name

Once the policy is named, the CLI changes to the configuration-port-policy level.

2. (Optional) Specify the port that will be checked by the policy.

Virtual ADX(config-port-policy-p1)#port 8080

Syntax: port port-num

3. Specify what protocol will be checked on the traffic that passes through the port.

Virtual ADX(config-port-policy-p1)#protocol http

Syntax: protocol protocol-value

If the protocol is not configured, the policy cannot be bound to a real server port.

For the protocol-value variable, enter a TCP or UDP port name or number. For TCP ports, enter

FTP (port 21), HTTP (port 80), IMAP4 (port 143), LDAP (port 389), LDAPS (port 636), MMS (port

1755), NNTP (port 119), PNM (port 7070), POP3 (port 110), RTSP (port 554), SMTP (port 25),

TELNET (port 23).

NOTE

Ports 20 and 21 both are FTP ports but on the Brocade Virtual ADX, the name "FTP" corresponds to port 21.

For UDP ports, enter DNS (port 53) or RADIUS (port 1812).


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Port policy

4. Configure a keepalive interval under a port policy.

Virtual ADX(config-port-policy-p1)#keepalive-interval 5

Syntax: [no] keepalive-interval seconds

Refer to “Configuring a keepalive interval under a port policy” on page 196 for more details.

5. (Optional) Enter the number of times the policy will be tried before the Brocade Virtual ADX marks the port as "UP" or "DOWN".

Virtual ADX(config-port-policy-p1)#retries 5

Syntax: retries num

The default is 3 tries.

6. (Optional) Specify the protocol value.

Virtual ADX(config-port-policy-p1)#protocol http url www.example3.com

Syntax: protocol protocol-options

Enter one of the following for protocol-options , specifying the values for the required parameters:

• http status-code min max

• http url url

• http content-match match-list

• dns addr-query value

• dns zone value

• {ldap | ldaps} username name

• {ldap | ldaps} password password

• {ldap | ldaps} search-base-dn distinguished-name

• radius key radius-key

• radius password value

• radius nas-ip { ipv4-addr | ipv6-addr }

• radius nas-port value

7. (Optional) Enable the Layer 4 check feature in the policy.

Virtual ADX(config-port-policy-p1)#l4-check

Syntax: l4-check

By default, Layer 7 health check is enabled; however, Layer 4 health check is not. You must enable Layer 4 health check if you want to use that feature.


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Binding the policy

After the policy is configured, return to the configuration level and bind the policy to a real server port.


Virtual ADX(config-rs-name)#port 1234 use-port-policy p1

Syntax: server real real-server-name real-server-ip-address

Syntax: [no] port port-num use-port-policy policy-name

For the policy-name variable, enter the name of the policy you created.

Once a policy is bound to a real server port, the Brocade Virtual ADX will use the values configured in the policy for health checks.

The Brocade Virtual ADX sends a health check to the port configured in the policy; however, if you do not configure a port number in the policy, the Brocade Virtual ADX sends the health check to the port to which it is bound.

NOTE

The port policy configuration will take precedence over a port profile.

Example 1:


Virtual ADX(config-port-policy-p1)#port 80


Virtual ADX(config-port-policy-p1)#retries 5

Virtual ADX(config-port-policy-p1)#exit


Virtual ADX(config-rs-r1)#port 1234 use-port-policy p1

Virtual ADX(config-rs-r1)#port 1234 keepalive

In Example 1, Port 1234 on Real Server 1 will be marked as “UP”, if the Layer 7 health check on

Port 80 on the server with the IP address of 10.10.1.101 passes.

Example 2:



Virtual ADX(config-port-policy-p2)#l4-check

Virtual ADX(config-port-policy-p2)#exit


Virtual ADX(config-rs-r1)#port 1234 use-port-policy p2

In Example 2, a port has not been configured for "policy p2," so the Brocade Virtual ADX will use the port to which the policy is bound. Port 1234 of real server r2 will be marked as "UP" if the health check to port 1234 on the 10.10.1.101 Server passes the Layer 4 health-check.

Example 3:

In the following example, Port Policy pp1 is configured with a keepalive interval of 5 seconds, while

Port Policy pp2 has a keepalive interval of 30 seconds.

Port Policy pp1 is bound to real server rs1 port 8080 and real server rs2 port 9090; therefore, these two ports have a 5 second keepalive interval.


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Port policy

Port Policy pp2 is bound to real server rs3 port 8080 and real server rs4 port 9090. These two ports have a keepalive interval of 30 seconds.

Virtual ADX(config)#server port-policy pp1

Virtual ADX(config-port-policy-pp1)#keepalive-interval 5

Virtual ADX(config-port-policy-pp1)#protocol http

Virtual ADX(config-port-policy-pp1)#protocol http url "GET /abc.html"

Virtual ADX(config-port-policy-pp1)#retries 3

Virtual ADX(config-port-policy-pp1)#exit




Virtual ADX(config-port-policy-pp2)#protocol http url "GET /xyz.html"





Virtual ADX(config-rs-r1)#port 8080 use-port-policy pp1






Virtual ADX(config)#server#real rs3








Configuring a keepalive interval under a port policy

You can specify a health check keepalive interval from under a port-policy definition.


Syntax: [no] keepalive-interval seconds

Enter from 1 through 120 for the seconds variable.

In the following example, real server rs1 port 8080 and real server rs2 port 9090 will have a keepalive interval of 5 seconds. Also, real server rs1 port 8080 and real server rs4 port 9080 will have a keepalive interval of 30 seconds.




Virtual ADX(config-port-policy-pp1)#protocol http url "GET /abc.html"






Virtual ADX(config-port-policy-pp2)#protocol http url "GET /xyz.html"




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After configuring the policy, bind it to a real server port. (Refer to

“Binding the policy” on page 195

for details.) For example:



Virtual ADX(config-rs-rs1)#port 8080 keepalive

Virtual ADX(config-rs-rs1)#port 8080 use-port-policy pp1
















Health check policy for VIP port

Overview of health check policy for VIP port

NOTE

The Brocade Virtual ADX does not support interval configuration under server port policy.

The Brocade Virtual ADX supports the binding of a server port policy on a real server port. Because multiple real server ports are bound to a single virtual port, the client has requested that the server port policy be bound to a virtual port. Once bound to a virtual port, the policy takes effect on all the real server ports that are bound to that virtual port. This method allows the running configuration to be reduced.


The command to turn on the health check policy feature for VIP port is under virtual server configuration.


Virtual ADX(config-virtual-server-v1) port 80

Virtual ADX(config-virtual-server-v1) bind 80 r1 80 r2 80 r3 80

Virtual ADX(config-virtual-server-v1) port 80 use-port-policy policy1

The Brocade Virtual ADX will now use the values configured under server port policy "policy1" to send out health-checks to ports 80 on R1, R2 and R3.


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Element health checks


Introduction

The Brocade Virtual ADX allows the creation of a health check that is customized for a given application server. Such definition is also known as element health check. You can specify the health check frequency, the number of retrials, and the number of other parameters for server health check.

Configuring element-action expressions

An element-action expression contains the IP address, protocol (TCP or UDP), and application port number for an application on an individual real server. If the Brocade Virtual ADX allows you to customize Layer 7 information for the application, then the element-action expression also can contain the customized Layer 7 information.

You can also change the following parameters for an application port when configuring an element-action expression:

• Health check type – For application types that are well-known to the Brocade Virtual ADX, you can specify whether you want to use the Layer 4 health check or the Layer 7 health check for the port. By default, the Brocade Virtual ADX uses the Layer 7 health check if the port one of the types that are well known to the Brocade Virtual ADX.

• Health check interval – By default, the Brocade Virtual ADX performs the health checks every 5 seconds. You can change the interval to a value from 2 through 120 seconds.

• Health retries – By default, if a reply to a health check is not received, the Brocade Virtual ADX will attempt the health check two more times before concluding that the application has failed the health check. You can change the number of retries to a value from 1 through 5 retries.

• Health check state – By default, the health check is enabled as soon as you configure it. You can disable or re-enable the health check from within the element-action expression for the check.

Specifying the IP address and application port parameters

To configure an element-action expression, enter commands such as the following. The commands in these examples specify the IPv4 or IPv6 address of the real server and the application port on the server.

Example for IPv4



Virtual ADX(config-hc-check1)#port http

Example for IPv6

Virtual ADX(config)#healthck check-v6 tcp

Virtual ADX(config-hc-check-v6)#dest-ip 2001:db8:2000::1

Virtual ADX(config-hc-check-v6)#port http


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These commands change the CLI to the configuration level for an element-action expression, then specify the IPv4 or IPv6 address of the real server and the application port on the server. Because the specified application is well-known to the Brocade Virtual ADX, the Brocade Virtual ADX automatically associates the default health check parameters for the port with the element-action expression. In this example, the port is HTTP (80), so the Brocade Virtual ADX associates the default HTTP health check parameters with the element-action expression. By default, the Brocade

Virtual ADX sends a HEAD request for the default page.

NOTE

You must specify the destination IP address before you can specify other health check parameters.

The software creates the health check policy only after you specify the destination IP address. If you try to specify another parameter before the destination IP address, the CLI displays an error message such as the following: Error - check1: Health-check element is undefined.

NOTE

If you do not specify the application port, the Brocade Virtual ADX will list the status of the health check as FALSE (failed).

To configure an element-action expression for a port number that is not well-known to the Brocade

Virtual ADX, enter commands such as the following.

Example for IPv4



Virtual ADX(config-hc-check1)#port 8080

Virtual ADX(config-hc-check1)#protocol http

Example for IPv6



Virtual ADX(config-hc-check-v6)#port 8080

Virtual ADX(config-hc-check-v6)#protocol http

These commands configure an element-action expression for unknown port 8080 and associate the default health check parameters for port 80 with the unknown port. To customize the Layer 7 health check parameters for a port, add the information with the protocol command, as in the following example.

Example for IPv4



Virtual ADX(config-hc-check1)#port 8080

Virtual ADX(config-hc-check1)#protocol http url "GET /sales.html"

Example for IPv6



Virtual ADX(config-hc-check-v6)#port 8080

Virtual ADX(config-hc-check-v6)#protocol http url "GET /sales.html"

The protocol command in this example changes the Layer 7 health check parameters for this HTTP port to a GET request for a page named sales.html.

Syntax: [no] healthck string { tcp | udp | boolean | icmp }


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This command begins configuration of the element-action expression. The string variable specifies the name for the expression and can be up to 20 characters long. The tcp | udp parameter specifies whether you are configuring an expression for a TCP application port or a UDP application port. There is no default.

Syntax: [no] dest-ip { ipv4-addr | ipv6-addr }

The ipv4-addr variable specifies the IPv4 address of the real server.



This command specifies the application port number.

NOTE

If you do not specify the server IP address and the application port, the Brocade Virtual ADX will list the status of the health check as FALSE (failed).

You can specify any valid number, or one of the following port names well-known to the Brocade

Virtual ADX:

• dns – port 53

• ftp – port 21. (Ports 20 and 21 both are FTP ports but in the Brocade Virtual ADX, the name

“ftp” corresponds to port 21.)

• http – port 80

• imap4 – port 143

• ldap – port 389

• nntp – port 119

• ntp – port 123

• pop2 – port 109

• pop3 – port 110

• radius – port 1812

• radius-old –The Brocade Virtual ADX name for UDP port 1645, which is used in some older

RADIUS implementations instead of port 1812.

• smtp – port 25

• snmp – port 161

• ssl – port 443

• telnet – port 23

• tftp – port 69

NOTE

If you enter the no port tcp/udp-port command to remove the port, the Brocade Virtual ADX also removes the protocol tcp/udp-port command (see below) if the port is well-known to the Brocade

Virtual ADX. The reason is that the Brocade Virtual ADX automatically uses the protocol that matches the well-known port. For ports that are not well-known types, the Brocade Virtual ADX does not remove the protocol. You must remove it separately.

Syntax: [no] protocol tcp/udp-port


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This command specifies a port whose health-check mechanism you want to use for the port specified by the port command. You need to use this command only if the port specified by the port command is not one of the ports listed above but the port is the same type as one of the ports listed above. For example, use this command if you want to use the DNS health-check mechanism for a port other than 53.

NOTE

You must specify the port using the port command before you enter the protocol command. If the port command specified a port that is well-known to the Brocade Virtual ADX, the Brocade Virtual

ADX automatically uses the protocol that matches the port; you do not need to specify it and cannot change it.

NOTE

If you remove the Layer 7 health check information (using a no protocol command), the application will fail the health check. If you want the Brocade Virtual ADX to use a Layer 4 health check instead, enter the l4-check command to change the health-check type to Layer 4.

If the port is not well-known to the Brocade Virtual ADX and you do not specify a protocol for the Layer

7 health check, but Layer 7 health checking is enabled for the port, the port will fail the health check.

Refer to the

“Changing the health-check type” on page 204.

For some ports, you also can customize the Layer 7 information sent with the health check. Here is the syntax.

Syntax: [no] protocol http | 80

[url “[GET | HEAD] [/] URL-page-name ” | port http status_code range [ range [ range [ range ]]] | content-match matching-list-name ]

This command changes one of the following HTTP health-check parameters. To change more than one of these parameters, enter a separate protocol http or protocol 80 command for each parameter.

• url “[GET | HEAD] [/] URL-page-name ” – This parameter specifies whether the HTTP health check performs a GET request or a HEAD request. For GET requests, you can specify the page that is requested. By default, a GET request asks for page “1.0”.

• port http status_code range [ range [ range [ range ]]] – This parameter changes the HTTP status codes that the Brocade Virtual ADX will accept as valid responses. Each range variable specifies the low number and high number in a range of status codes. You can specify up to four ranges (total of eight values). To specify a single message code for a range, enter the code twice. For example, to specify 200 only, enter the port http status_code 200 200 command.

For SLB, the default status code range is from 200 through 299. If the server’s reply to the health check contains a status code within this range, the Brocade Virtual ADX considers the

HTTP application to be healthy.

• content-match matching-list-name – This parameter attaches a match list for an HTTP content verification health check to the real server. An HTTP content verification health check is a type of Layer 7 health check in which the Brocade Virtual ADX examines text in an HTML file sent by a real server in response to an HTTP keepalive request. The Brocade Virtual ADX searches the text in the HTML file for user-specified selection criteria and determines whether the HTTP port on the real server is alive based on what it finds. The selection criteria used in HTTP content


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Element health checks verification is contained in a matching list that is attached to one or more real servers. The following is an example of the commands used to set up a matching list. For information on

how to configure the match lists, refer to “Configuring HTTP content matching lists” on page 208.

Syntax: [no] protocol dns | 53 [addr_query " name " | zone zone-name ]

This command changes one of the following DNS health-check parameters. To change more than one of these parameters, enter a separate protocol dns or protocol 53 command for each parameter.

• addr_query " name " – This parameter specifies a domain name to be requested from the real server by the Brocade Virtual ADX. If the server successfully responds with the IP address for the domain name, the server passes the health check. There is no default.

• zone zone-name – This parameter specifies a DNS zone name. The Brocade Virtual ADX sends a Source-of-Authority (SOA) request for the zone name. If the server is authoritative for the zone and successfully responds to the SOA request, the server passes the health check. There is no default.

NOTE

If you do not configure one of these parameters, the DNS port will fail the health check.

Syntax: [no] protocol radius | 1812 [username string ] | [password string ] | [key string ]

This command changes one of the following RADIUS health-check parameters. The health check requests values that are configured on the RADIUS server. To change more than one of these parameters, enter a separate protocol radius or protocol 1812 command for each parameter.

• username string – This parameter specifies an authentication username on the server.

• password string – This parameter specifies an authentication password on the server.

• key string – This parameter specifies an authentication key on the server.

Syntax: [no] protocol ldap | 389 [ num ]

This command changes the LDAP version. The health check sent by the Brocade Virtual ADX differs depending on the version. You can specify 2 or 3. The default is 3.

Using SSL health checks in a health check policy

When SSL health checks are used in a health check policy, by default the simple SSL health check is used. The Brocade Virtual ADX sends the server an SSL client hello with the SSL SID set to 0; if the server responds, it passes the health check. However, if you use the protocol ssl use-complete command in a health check policy, it causes the Brocade Virtual ADX to negotiate an SSL connection and send a GET or HEAD request to the server.

For example, the following commands create a health check policy to test IP address 10.10.10.50, using SSL health checks.



Virtual ADX(config-hc-check4)#port ssl

Virtual ADX(config-hc-check4)#protocol ssl use-complete

Virtual ADX(config-hc-check4)#protocol ssl url "GET /secure.htm"

Virtual ADX(config-hc-check4)#protocol ssl status-code 200 200


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Virtual ADX(config-hc-check4)#protocol ssl content-match m1


Virtual ADX(config-hc-check4)#enable

Virtual ADX(config-hc-check4)#exit

Syntax: [no] protocol ssl use-complete

Changing the health-check interval and retries

By default, the Brocade Virtual ADX performs a health check every 5 seconds. If a reply is not received, the Brocade Virtual ADX will attempt the health check two more times before concluding that the application has failed the health check. You can change the number of seconds the

Brocade Virtual ADX will wait for a reply to a health check and the number of retries.

NOTE

The number of retries is the total number of attempts the Brocade Virtual ADX will make. If you use the default interval and retries values, the Brocade Virtual ADX will send up to three health-check packets, at 5-second intervals. If a server does not respond within 15 seconds of the time the

Brocade Virtual ADX sent the first health-check packet, the server fails the health check and the

Brocade Virtual ADX concludes that the server is not available.

To change the interval for a health check, enter a command such as the following at the configuration level for the element-action expression that contains the health check.

Virtual ADX(config-hc-check1)#interval 30

Syntax: [no] interval secs

You can specify from 2 through 120 seconds. The default is 5 seconds.

To change the number of retries for a health check, enter a command such as the following at the configuration level for the element-action expression that contains the health check.

Virtual ADX(config-hc-check1)#retries 4

Syntax: [no] retries num

You can specify from 1 through 5 retries. The default is 3 retries.

NOTE

You also can globally change the interval and retries for an application port by editing its port profile.

Refer to “Configuring a port profile” on page 188.


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Changing the health-check type

For TCP application ports, you can change the health-check type between Layer 4 and Layer 7. By default, the Brocade Virtual ADX performs a Layer 7 health check in the following cases:

• The port is one of the following ports well-known to the Brocade Virtual ADX:

FTP – port 21. (Ports 20 and 21 both are FTP ports but on the Brocade Virtual ADX, the name “FTP” corresponds to port 21.)

HTTP – port 80

IMAP4 – port 143

LDAP – port 389

MMS – port 1755

NNTP – port 119

PNM – port 7070

POP3 – port 110

RTSP – port 554

SMTP – port 25

SSL – port 443

TELNET – port 23

• The port is not well-known to the Brocade Virtual ADX but you used the protocol command to specify the protocol of one of the well-known ports. By specifying the protocol, you configure the Brocade Virtual ADX to use the protocol’s Layer 7 health-check method for the port.

If the TCP port is not one of the ports above or you did not specify a Layer 7 health-check method

(using the protocol command), the Brocade Virtual ADX uses the Layer 4 health check for TCP.

NOTE

Changing the health-check type for UDP application ports has no effect. If the application port is

RADIUS (1812) or DNS (53) or uses the health-check method of one of these ports, the Brocade

Virtual ADX uses a Layer 7 health check. Otherwise, the Brocade Virtual ADX uses the Layer 4 health check for UDP.

The Layer 7 health-check methods differ depending on the application:

• TCP – The Brocade Virtual ADX attempts to engage in a normal three-way TCP handshake with the port on the real server:



If the Brocade Virtual ADX receives the SYN ACK, the Brocade Virtual ADX sends a TCP

RESET, satisfied that the TCP port is alive.

• UDP – The Brocade Virtual ADX sends a UDP packet with garbage (meaningless) data to the

UDP port:


If the server does not respond at all, the Brocade Virtual ADX assumes that the port is alive and received the garbage data. Because UDP is a connectionless protocol, the Brocade

Virtual ADX and other clients do not expect replies to data sent to a UDP port. Therefore, lack of a response is a good outcome.


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The l4-check command configures the Brocade Virtual ADX to use the Layer 4 health check for the application port in the element-action expression. Because the application port in this element-action expression is HTTP, the Brocade Virtual ADX will use the Layer 4 health check for

TCP.


Syntax: [no] l4-check | l7-check

Changing the health-check state

Once you configure an element-action expression, the health check in the expression is enabled by default. To disable the health check, enter the following command at the configuration level for the element-action expression.

Virtual ADX(config-hc-check1)#disable

Syntax: [no] disable | enable

NOTE

Health checking (keepalive) also must be enabled on the port profile level or the real server level.

Otherwise, the health-check policy is used during initial bringup of the server but is not used for periodic health checks after the server is brought up.

NOTE

If the health check for an application on a server is disabled, the Brocade Virtual ADX assumes that the server and application are healthy and continues to send client requests to the server.

NOTE

If you change the health-check state from within the element-action expression, this state overrides the health-check state configured in the port profile for the application port or in the real server configuration.

NOTE

You can globally enable or disable all health-check policies. Refer to

“Globally disabling all health-check policies” on page 222.

Attaching a health-check policy to an application port on a server

After you configure logical expressions, you can attach them to application ports on real servers.

The Brocade Virtual ADX does not begin sending health-check packets until you attach the policy to a real server port.

To attach a health-check policy to an application port on a server, enter commands such as the following.


Virtual ADX(config-rs-R1)#port 80 healthck “check1”

This command configures the Brocade Virtual ADX to base the health of application port 80 on real server R1 on the results of the check1 health-check policy.


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Displaying health-check policies and their status

To display a list of the configured health-check policies and their current status, enter the following command.

Virtual ADX(config-hc-check1)#show healthck

Total nodes: 6; Max nodes: 128

Name Value Enable Type Dest-IP Port Proto Layer

--------------------------------------------------------------------------------

check1 TRUE YES tcp 10.10.10.50 http http l4-chk

check2 TRUE YES tcp 10.10.10.40 http http l7-chk

check3 TRUE NO udp 10.10.10.30 http http l4-chk

check4 TRUE NO udp 10.10.10.40 http http l4-chk

httpsrvr TRUE YES and check1 check2

nested1 N/A na and check1 check2

nested2 N/A na or check3 check4

Syntax: show healthck

Table 19 displays the health-check policy status.

TABLE 19 Health-check policy status

Field Description

Total nodes

Max nodes

Name

Value

Enable

Type

Dest-IP

Port

The number of health-check policies in the configuration. The number includes attached and unattached policies.

The maximum number of health-check policies you can configure.

The element-action expression or policy name.

The current value of the policy. The value can be one of the following:

•

TRUE – The most recent health check performed using this policy was successful. The

Brocade Virtual ADX received a valid reply to the health check.

•

FALSE – The most recent health check performed using this policy was unsuccessful.

•

N/B – The health check is not bound to any VIP and thus is not in use.

•

N/A (Not Attached) – The policy is not attached to a real server.

NOTE: If the policy is disabled, this value is always TRUE, because the Brocade Virtual ADX assumes a server is healthy unless its health check is enabled and the server has not responded appropriately to the health check.

The state of the policy, which can be one of the following:

•

YES – The policy is enabled.

•

NO – The policy is disabled.

• na (not applicable) – This field does not apply to the policy. This value indicates that the policy is not attached to a real server.

The element-action expression or policy type. For Layer 3 health checks, this information consists of ICMP and the IP address tested by the health check.

Values can be one of the following:

• tcp – An element-action expression for a TCP application port.

• udp – An element-action expression for a UDP application port.

• and – A policy containing element-action expressions joined by AND.

• or – A policy containing element-action expressions joined by OR.

For element-action expressions, the IP address of the real server. For policies, this field shows the element-action expressions in the policy.

The value “ - ”indicates that the IP address has not been specified.

For element-action expressions, the application port. This field does not apply to policies.


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TABLE 19 Health-check policy status (Continued)

Field Description

Proto

Layer

For element-action expressions, the health-check method to be used for the port.

NOTE: If the value is " - ", the protocol has not been specified and the port is not well-known to the Brocade Virtual ADX.

The type of health check, which can be one of the following:

• l4-chk – Layer 4 TCP or UDP health check.

• l7-chk – Layer 7 application-specific health check.

Displaying health-check policy statistics

To display health-check policy statistics, enter the following command.

Virtual ADX(config)#show healthck statistics

Ping Statistics:

Sent: 1524 Received: 1524

Invalid Replies: 0 Dropped Replies: 0

Syntax: show healthck statistics

Table 20 displays the health-check policy statistics.

TABLE 20 Health-check policy statistics

Field Description

Sent

Received

The number of health-check packets sent by bound health-check policies.

The number of replies received. A received reply results in a true condition.

NOTE: Since the Brocade Virtual ADX retries a health check if a reply is not received, a higher sent count than receive count does not necessarily indicate a problem.

Invalid Replies The number of replies that were received that had an invalid ID. The Brocade Virtual ADX is sometimes able to resolve an invalid ID. If the Brocade Virtual ADX cannot resolve the invalid

ID, the device drops the reply and increments the Dropped Replies counter.

Dropped Replies The number of replies that the Brocade Virtual ADX dropped.

Clearing health-check policy statistics

To clear health-check policy statistics, enter the following command.

Virtual ADX(config)#clear healthck statistics

Syntax: clear healthck statistics


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Health check with content match


Content match for HTTP

Configuring HTTP content matching lists

The Brocade Virtual ADX currently supports compound and simple content-matching statements under the match-list configuration. This enhancement adds support for "start" and "end" statements in the match-list configuration.

Virtual ADX(config)#http match-list m1

Virtual ADX(config-real-server-r1)#down start "404"

Virtual ADX(config-real-server-r1)#default up


Virtual ADX(config-real-server-r1)#up end "found"

Virtual ADX(config-real-server-r1)#default down

The first match list m1 would cause the Brocade Virtual ADX to mark the port failed if the text "404" is found at the beginning of the reply from the server. If the text is not found, the Brocade Virtual

ADX would mark the port UP, as the default configured is UP.

In the second example above, for match-list m2, Brocade Virtual ADX would mark the port UP, if the text "found' is present at the end of the reply from the server.

An HTTP content verification health check is a type of Layer 7 health check in which the Brocade

Virtual ADX examines text in an HTML file sent by a real server in response to an HTTP keepalive request. The Brocade Virtual ADX searches the text in the HTML file for user-specified selection criteria and determines whether the HTTP port on the real server is alive based on what it finds.

The selection criteria used in HTTP content verification is contained in a matching list that is bound to one or more real servers.

To configure a matching list, enter commands such as the following.


Virtual ADX(config-http-ml-m1)#down simple "404"

Virtual ADX(config-http-ml-m1)#down simple "File Not Found"

Virtual ADX(config-http-ml-m1)#exit

The first command sets the name of the matching list and enters the HTTP matching list CLI level.

The first down statement looks for the text “404” in the HTML file sent from the real server in response to an HTTP keepalive request; the second down statement looks for the text “File Not

Found.” If either of these text strings are found in the HTML file, the Brocade Virtual ADX marks port 80 (HTTP) on the real server FAILED. If neither of the text strings are found, the Brocade Virtual

ADX marks the port ACTIVE.

Syntax: http match-list matching-list-name

Syntax: down I up simple text [log]

The down simple and up simple statements specify the selection criteria in the matching list.

NOTE

There is a limit of 200 selection criteria statements for all HTTP matching lists; that is, the total number of up and down statements in all HTTP matching lists on the Brocade Virtual ADX must not exceed 200.


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NOTE

The HTTP page file size returned by the server should be less than 100kb.

When an HTML file meets more than one set of selection criteria in a matching list, the Brocade

Virtual ADX takes one of the following actions:

• If the strings that meet the selection criteria are different, the Brocade Virtual ADX takes action based on the string that comes first in the file. For example:


Virtual ADX(config-http-ml-m2)#down simple "monkey"

Virtual ADX(config-http-ml-m2)#up simple "elephant"


The selection criteria in the matching list above would cause the Brocade Virtual ADX to mark the port FAILED if the text "monkey" is found and ACTIVE if the text "elephant" is found. If the

HTML file has the text "monkey" at the beginning and "elephant" at the end, the Brocade Virtual

ADX would mark port 80 on the real server FAILED, because "monkey" occurs first in the file.

• If a string that meets the selection criteria is a subset of another, the longer string takes precedence, regardless of where it occurs in the file. For example:


Virtual ADX(config-http-ml-m3)#down simple "elephant"

Virtual ADX(config-http-ml-m3)#up simple "elephantine"


In this example, Brocade Virtual ADX would mark the port FAILED if the text “elephant” is found and ACTIVE if the text “elephantine” is found. If the HTML file has the text “elephant” at the beginning and “elephantine” at the end, the Brocade Virtual ADX would mark port 80 on the real server ACTIVE, because “elephantine” is longer than “elephant”.

The following is an example of a matching list that uses compound selection criteria, in which the beginning and ending parts of selection criteria are specified.


Virtual ADX(config-http-ml-m4)#up compound "monkey see" "monkey do" log

Virtual ADX(config-http-ml-m4)#down compound "500" "Internal Server Error" log

Virtual ADX(config-http-ml-m4)#down compound "503" "Service Unavailable" log

Virtual ADX(config-http-ml-m4)#default down


In this example, the default down command causes port 80 on the real server to be marked FAILED if none of the selection criteria are found in the HTTP response message.

Syntax: down | up compound start end [log]

Syntax: default down | up

In this matching list, the up and down commands include the compound parameter, which allows you to specify beginning and ending parts of a set of selection criteria. Text that begins with the first part and ends with the second part meets the selection criteria.

In this example, the up command specifies that if the HTML file sent from the real server in response to an HTTP keepalive request contains a text string that begins with the text “monkey see” and ends with the text “monkey do”, port 80 on the real server is marked ACTIVE. The down commands specify that if the HTML file contains a text string that begins with “500” and ends with

“Internal Server Error” or begins with “503” and ends with “Service Unavailable”, the port is marked FAILED.


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The default command specifies what happens if none of the HTML text in the HTTP response message meets the selection criteria. You can specify either up or down; the default is up. If the real server responds to the health check with a RST, the port is marked ACTIVE or FAILED depending on what was specified in the default statement in the matching list.

The log parameter causes the following warning message to be logged when the selection criteria is met.

00d00h00m00s:W:HTTP match-list matching-list with compound pattern1 start and pattern2 end

Alert: bring server down and Extract message: text-between-start-and-end-pattern

In the example, at the successful completion of an HTTP content verification health check, the following message would be logged; that is, if the HTML file sent from the real server in response to an HTTP keepalive request contains a text string that begins with the text “monkey see” and ends with the text “monkey do”.

Virtual ADX#show logging

Syslog logging: enabled (0 messages dropped, 0 flushes, 0 overruns)

Buffer logging: level ACDMEINW, 1 messages logged

level code: A=alert C=critical D=debugging M=emergency E=error

I=informational N=notification W=warning

Dynamic Log Buffer (50 entries):

02d04h47m12s:W:HTTP match-list m4 with compound pattern1 "monkey see" and pattern2 "monkey do" Alert: bring server up and Extract message: This web page is configured correctly

Displaying HTTP match lists

To display the contents of matching lists configured on the Brocade Virtual ADX, enter the following command.

Virtual ADX#show http match-list http match-list m1 down simple "404" down simple "File Not Found" http match-list m4 default down up compound "monkey see" "monkey do" log down compound "500" "Internal Server Error" log down compound "503" "Service Unavailable" log

Syntax: show http match-list

Binding the matching list to the real servers

To enable HTTP content verification on the Brocade Virtual ADX, you bind the matching list to one or more real servers, by entering commands such as the following.


Virtual ADX(config-rs-rs1)#port http content-match m4

Virtual ADX(config-rs-rs1)#port http url "GET/monkey.html"


Syntax: server real-name real-server-name ip-addr

Syntax: port http content-match matching-list-name

Syntax: port http url “[GET | HEAD] [/] URL-page-name ”


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In this example, the port http content-match m4 command binds matching list m4 to real server rs1. HTTP response messages coming from real server rs1 are examined using the selection criteria in matching list m4.

The port http url command sets the method used for HTTP keepalive requests and the URL of the page to be retrieved. This command is used in HTTP content verification health checks because the default method and URL page for HTTP keepalive requests used in HTTP health checks, “HEAD

/1.0”, does not return an HTML file that the Brocade Virtual ADX can search and verify. You can instead specify the GET method, which does return an HTML file that can be examined using the matching list.

Content match for non-HTTP ports

Configuring scripted health checks

You can configure scripted health checks (also known as content checking), which are content verification health checks for ports that do not use one of the well-known port numbers recognized by the Brocade Virtual ADX. Previous releases supported content verification health checks on port

80 only.

In a scripted health check, the Brocade Virtual ADX opens a connection to a port on a real server by sending a SYN packet. The Brocade Virtual ADX completes the three-way handshake and then waits for the server to send a packet containing ASCII strings in response. It then searches for the configured ASCII string in the received packet. The port on the real server is then marked ACTIVE or

FAILED, based on configuration settings in the matching list. For example, a matching list can be configured to mark a port ACTIVE or FAILED if the string is found, or mark the port ACTIVE or FAILED if the string is not found.

If no response is received within the configured interval (the default is five seconds), the Brocade

Virtual ADX sends an RST and retries the health check. After the configured number of retries (the default is two retries), if the server still does not respond, the Brocade Virtual ADX marks the server port FAILED.

A scripted health check can also be part of a health-check policy. In this case, the scripted health check checks the health of a configured port in the policy. The health-check policy can be evaluated to true or false depending on the response from the server.

Follow the steps given below to configure a scripted health check.

1. Configuring a port profile

2. Configuring a matching list

3. Binding the matching list to the real server

Configuring a port profile

Port profiles enable you to globally configure the attributes for individual TCP/UDP ports. A scripted health check will not work on a TCP port that does not have a profile, because the Brocade Virtual

ADX assumes any port without a profile is a UDP port, and will perform UDP health checking on the port. To use a scripted health check on a TCP port, you must create a port profile and explicitly identify the port as a TCP port.


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The following commands configure a port profile for port 12345 and specify that the port is a TCP port. The no-fast-bringup command is necessary because it prevents the Brocade Virtual ADX from marking a port ACTIVE until it passes both Layer 4 and Layer 7 health checks.


Virtual ADX(config-port-12345)#tcp

Virtual ADX(config-port-12345)#no-fast-bringup


Syntax: tcp | udp [keepalive interval retries ]

Syntax: no-fast-bringup

Configuring a matching list

The selection criteria used in a content verification health check is specified in a matching list that is bound to one or more real servers. The syntax used for creating a matching list for scripted health checks is the same as that used for creating a matching list for HTTP content verification health checks.

The following is an example of a matching list that will mark a port ACTIVE if the string “FTP service” is found in the response from the real server. If this text is not found, the port on the real server is marked FAILED.


Virtual ADX(config-http-m1-m1)#up simple "FTP service"

Virtual ADX(config-http-m1-m1)#default down


In this example, the default down command causes the port on the real server to be marked

FAILED if the selection criteria is not found in the response from the server.

For information on the command syntax, refer to “Configuring HTTP content matching lists” on page 208.

Binding the matching list to the real server

To enable the scripted health check on the Brocade Virtual ADX, you bind the matching list to one or more real servers. For example, to bind matching list m1 to real server R, enter commands such as the following.

Virtual ADX(config)#server real R 10.10.10.50

Virtual ADX(config-rs-R)#port 12345 content-check m1

Syntax: port portnum content-check matching-list-name

The portnum variable specifies a non-well-known port. You cannot specify a well-known port for a scripted health check.

The matching-list-name variable specifies a previously configured matching list. If the matching-list-name does not refer to an existing matching list, the port on the real server is marked

FAILED when the health check is performed.


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Using a scripted health check in a health-check policy

A scripted health check can be used in a health-check policy. A health-check policy is a group of one or more health checks attached to a real server port. When the scripted health check checks the health of a destination port specified in the policy, the health-check policy can be evaluated to true or false depending on the response from the server.

To use a scripted health check with a health-check policy, you configure a matching list, then configure the health-check policy.

For example, when the following matching list is used with a health-check policy, it will evaluate the policy to true if the string “FTP service” is found in the response from the real server. If this text is not found, the policy is evaluated to false.


Virtual ADX(config-http-m1-m1)#up simple "FTP service"



The default down command causes the policy to be evaluated to false if the selection criteria is not found in the response from the server. If the real server responds to the health check with an RST, the policy is evaluated to true or false depending on what was specified in the default statement in the matching list.

Configuring a health check policy

The following commands create a health check policy for TCP port 1234 on VIP 10.10.10.10.

Matching list m1 is bound to this policy.



Virtual ADX(config-hc-check1)#port 1234 content-check m1


Syntax: [no] healthck element-name protocol

Syntax: [no] dest-ip { ipv4-addr | ipv6-addr }



Syntax: [no] port portnum content-check matching-list-name

Syntax: [no] l7-check

Note that the dest-ip ipv4-addr or ipv6-addr command must be the first command entered for a health-check policy. If this is not the first command entered for the policy, an error message is displayed.

If the matching-list-name variable does not refer to an existing matching list, the policy is evaluated to false.

The l7-check command is required to ensure that the Brocade Virtual ADX performs a Layer 7 health check. If this command is omitted, the Brocade Virtual ADX performs only a Layer 4 health check, and not the scripted health check.


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Scripted health check enhancement on real servers

When the port port-name command is configured with the content-check send option to send a string to the server, the Brocade Virtual ADX establishes a TCP connection, and on receiving a

SYN-ACK, sends the configured string to the server. The device then waits for the server to send

ASCII text and then brings the server port up or down, based on the configured match-list policy.

In the following example, the Brocade Virtual ADX sends a SYN packet to server 10.10.1.31, port

1234. On receiving a SYN-ACK from the server, the Brocade Virtual ADX sends a TCP packet with the data "how are you". The Brocade Virtual ADX then waits for the server. In the data of the TCP packets sent by the server, the Brocade Virtual ADX will look for the pattern "good". If found, the

Brocade Virtual ADX marks the real server r1 port 1234 as UP; otherwise, it will mark the port as

DOWN.



Virtual ADX(config-rs-r1)#port 1234 content-check m1

Virtual ADX(config-rs-r1)#port 1234 content-check send "how are you"



Virtual ADX(config-http-ml-m1)#up simple good


Syntax: [no] port port-name content-check match-list-name

Syntax: [no] port port-name content-check send " string "

NOTE

The l7-check command must be enabled in order for the Brocade Virtual ADX to send the script. If the l4-check command is configured, the Brocade Virtual ADX will establish a TCP connection and then send an RST.

Binary scripted health check

The scripted health check feature allows the Brocade Virtual ADX to complete 3-way TCP handshake followed by sending an ASCII string and waiting for an appropriate response before marking real server health. If the customer is running an application that can not interpret data in

ASCII format, this methodology will not help.

Binary scripted heath check allows the application switch to send binary data (carray format) after doing a 3-way TCP handshake with the backend server. The Brocade Virtual ADX would then mark the health of the server as pass or failed depending on the response content match (again in carray format). This feature is implemented using the content-check-array option within the real server port command as shown in the following sample configuration.


Virtual ADX(config-rs-rs1)#port 1111 content-check-carray m1

Virtual ADX(config-rs-rs1)#port 1111 content-check-carray send “0xe1,0xe2,0xe3,

0xe4”




Virtual ADX(config-http-m1-m1)#up simple 0xca,0xcb,0xcd,0xce

Syntax: [no] port port-name content-check-carray match-list-name

The port-name variable defines the port where the binary scripted health check is performed.


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The match-list-name variable defines the name of the matching list used in the binary scripted health check.

Syntax: [no] port port-name content-check-carray send Carray-data

The port-name variable defines the port where the binary scripted health check is performed.

The Carray-data variable defines the binary data in C array format used in the binary scripted health check. The maximum number of characters supported is 2000.

NOTE

Sending binary data after a 3-way handshake is not mandatory.

Scripted health check for UDP ports

The scripted health check feature enhances the TrafficWorks software to perform customizable scripted health checks for UDP protocol. in addition to the current TCP protocol, this feature is available on any out-of-band port and is able to use the existing L7 content check features.

The Brocade Virtual ADX currently supports scripted health-checks on TCP ports. This feature adds support for scripted health-checks on UDP ports.

When scripted health-check is configured on a UDP port, the Brocade Virtual ADX will send out a

UDP packet with the content-check-send data if configured; otherwise, it will send out a UDP packet. Then it expects a UDP reply with ASCII content and will do the content-check on the data received. It will mark the port UP or DOWN according to the configuration in the match-list.

If an ICMP message is received, then the port will be brought down.


There is no new CLI added for this feature. The CLI is the same as that used for scripted health-checks for TCP ports. Previously the CLI was restricted to TCP ports, while now that restriction has been removed.



Virtual ADX(config-rs-r1)#port 1234 content-check m1

Virtual ADX(config-rs-r1)#port 1234 content-check send "how are you"


Virtual ADX(config-http-ml-m1)#up simple good


In the above example, the Brocade Virtual ADX will send and UDP packet containing the ASCII string

"how are you." On receiving the reply, Brocade Virtual ADX will search for the string "good." If found, it will mark port 1234 UP, otherwise it will mark the port DOWN.


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Boolean health checks


Boolean health-check policies

You can configure a group of Layer 4 and Layer 7 health checks as a health-check policy and associate the group with a specific application port on a real server.

1 Health-check policies enable you to assess the health of any application port using the health-check mechanisms for ports well-known to the Brocade Virtual ADX. In addition, health-check policies let you use multiple checks with different parameters and base a port’s health on successful completion of all or any one of the individual checks in the policy.

Depending on the conditions you specify when you configure a health-check policy, the Brocade

Virtual ADX will bring the application port on a server down in one of the following cases:

• Any one of the servers fails its health check (individual health checks combined using AND condition) – In this case, all servers in the policy must pass their health checks. Otherwise, the

Brocade Virtual ADX considers all of the servers to have failed the health checks and brings down the application on all servers that are checked by the policy.

• All of the servers fail their health checks (individual health checks combined using OR condition) – In this case, an application port remains up as long as at least one of the servers checked by the policy passes its health check.

For finer control, you can combine OR and AND conditions.

Health-check policy

Health-check policies consist of element-action expressions and logical expressions.

• An Element-action expression consists of the IP address of the server, the Layer 4 protocol

(TCP or UDP), and the application port on the server. For some applications, the element-action expression can also include Layer 7 application-specific health check information.

• A Logical expression is a set of element-action expressions joined by the Boolean operators

OR, AND or NOT.

To create a health-check policy that is successful if at least one of the applications passes its health check, use OR.

To configure a health-check policy that is successful only if the Brocade Virtual ADX receives a successful reply from all servers and application ports in the policy, use the operator AND.

To configure a health-check policy that is successful if none of the elements responds to the health check, use the operator NOT.

You can use the same element-action expressions in multiple logical expressions if desired. You can configure up to 254 health-check policies.

216

1.

Real servers include those added using the server real-name command and those added using the server remote-name command. Generally, both types of servers are referred to as real servers. An application port is a port that uses the TCP or UDP protocol. You associate health-check policies with TCP or UDP ports on the real servers (not with physical ports on the servers).


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Follow the steps given below to use a health-check policy.

1. Configure the element-action expressions.

2. Configure the health-check policy using element-action expressions and logical expressions joined by the operators AND or OR or NOT.

3. Attach logical expressions to application ports on specific real servers. A health check policy does not take effect until you attach it to an application port on a server.

NOTE

A health-check policy does not take effect (begin sending health check packets) until you attach the policy to an application port on a real server.

Configuring boolean health check

A health-check policy consists of one or more element-action expressions. When a logical expression contains multiple element-action expressions, the policy also contains the logical operator AND or OR or NOT. You can use a health-check policy as an element-action expression in another policy.

To configure a health-check policy, enter commands such as the following.

Virtual ADX(config)#healthck "httpsrvr" boolean

Virtual ADX(config-hc-httpsrvr)#and "check1" "check2"

These commands configure a health-check policy that uses the element-action expressions

"check1" and "check2". Because the AND operator is used, the real servers in both "check1" and

"check2" must reply successfully for the health check to be successful. If only one of the servers replies, the health check is unsuccessful and the Brocade Virtual ADX stops using all the server application ports in the health-check policy "httpsrvr".

Syntax: [no] healthck " policy-name " boolean

Syntax: and | or " element-name " " element-name "

The policy-name variable specifies the name of the health-check policy. The name can be up to

20 characters long. The name cannot contain blanks.

The and or or command specifies a logical operator in the health-check policy. You can enter two element-action expressions along with the logical operator and, or or not.

• If you specify and, the policy evaluates to true only if all elements (IP addresses) respond to the health check.

• If you specify or, the policy is true if at least one of the elements responds to the health check.

• If you specify not, the policy is true if none of the elements responds to the health check.

If you are configuring a boolean UDP health check policy, define the static next hop MAC address along with a VLAN ID for on that link; otherwise, the Brocade Virtual ADX cannot learn the next-hop-mac-address of that link. Enter commands such as the following to define a static next-hop-mac-address and a VLAN-ID.

Virtual ADX(config-link-link3)#next-hop-mac-address 00e0.5208.dd8e vlan-id 40


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The address 00e0.5208.dd8e is the MAC address of Link3's access router interface. The vlan-id

40 is the Brocade Virtual ADX’s interface, that is used to connect Link3's access router is in VLAN

40

Syntax: next-hop-mac-address mac-address vlan-id vlan#

Using a nested health-check policy

If you want to use a single health-check policy to test more than two IP addresses, configure health-check policies for all the IP addresses, and use them in another health-check policy. For example, to create a health-check policy that tests four IP addresses, enter commands such as the following.




Virtual ADX(config-hc-check1)#healthck check2 tcp









The commands above configure four element-action expressions, one for each of four servers. The following commands configure two health-check policies, each of which contains two of the element-action expressions.

Virtual ADX(config-hc-check4)#healthck nested1 boolean

Virtual ADX(config-hc-nested1)#or check1 check2

Virtual ADX(config-hc-nested1)#healthck nested2 boolean

Virtual ADX(config-hc-nested2)#or check3 check4

The following command creates a health-check policy that contains the two policies configured above. The result is a single health-check policy for all four IP servers.

Virtual ADX(config-hc-nested2)#healthck checkall boolean

Virtual ADX(config-hc-checkall)#or nested1 nested2

In this example, the OR logical operator is used in all the policies. Therefore, the "checkall" health check is successful if at least one of the four servers responds. To create more restrictive policies, you can use the AND logical operator. For example, if the AND operator is used in this configuration instead of OR, the health check is successful only if all four servers respond.

You also can combine policies that use AND with policies that use OR in nested health-check policies.


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Basing an alias port’s health on the health of its master port

By default, the Brocade Virtual ADX performs health checks for alias ports independently of the master ports on which they are based. For example, if you configure alias port 8080 and base the port on port 80 (its master port), the Brocade Virtual ADX checks the health of 80 and 8080 independently.

You can configure the Brocade Virtual ADX to check the health of the master port only and base the health of the alias ports on the master port.

You can base an alias port’s health on the health of one of the following TCP ports:

• FTP – port 21 (ports 20 and 21 both are FTP ports but on the Brocade Virtual ADX, the name

“FTP” corresponds to port 21)

• HTTP – port 80

• IMAP4 – port 143

• LDAP – port 389

• MMS – port 1755

• NNTP – port 119

• PNM – port 7070

• POP3 – port 110

• RTSP – port 554

• SMTP – port 25

• SSL – port 443

• TELNET – port 23

You cannot base an alias port’s health on the health of a UDP port or a port that is not well-known to the Brocade Virtual ADX.

NOTE

The health checks for the alias ports must be enabled. Otherwise, the Brocade Virtual ADX will not check the master port’s state, and the alias port will not go down when the master port goes down.

To configure an alias port’s health to be based on its master port’s health, edit the alias port’s profile by entering commands such as the following.


Virtual ADX(config-port-8080)#tcp keepalive use-master-state

Syntax: [no] tcp keepalive use-master-state

The command is entered at the port profile level.


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Basing a port’s health on the health of another port

You can configure the Brocade Virtual ADX to base the health of a port that is not well-known to the

Brocade Virtual ADX on the health of one of the following ports that are well-known to the Brocade

Virtual ADX:

• DNS (port 53)

• FTP (port 21). Ports 20 and 21 both are FTP ports but on the Brocade Virtual ADX, the name

“FTP” corresponds to port 21.

• HTTP (port 80)


• LDAP (port 389)

• POP3 (port 110)

• NNTP (port 119)

• SMTP (port 25)

• TELNET (port 23)

To base a port’s health on the health of another port, enter a command such as the following.

Virtual ADX(config-port-1234)#tcp keepalive port 80

Syntax: tcp | udp keepalive port TCP/UDP-portnum

The command in this example configures the Brocade Virtual ADX to base the health of port 1234 on the health of port 80 (HTTP). If the health of port 80 changes, the Brocade Virtual ADX applies the change to port 1234.

NOTE

You cannot base the health of a port well-known to the Brocade Virtual ADX on the health of another port, whether the port is well-known or not well-known.

Reassign threshold

The reassign threshold specifies the number of contiguous inbound TCP-SYN packets a real server can fail to respond to before the Brocade Virtual ADX changes the application state to FAILED and

the server state to TEST. The server and application states are described in “Server and application port states” on page 184.

The value of an application's reassign counter is reset to 0 when the Brocade Virtual ADX receives a TCP SYN ACK from the application. No other type of traffic can clear this field. This reassign counter can be seen with the show server real name_or_ip detail command where the name_or_ip variable is the real server's ASCII name or IP address.

If a real server seems to be triggering the reassign threshold too frequently, you can increase the reassign threshold. The reassign threshold is disabled by default. To modify the reassign threshold to 215, enter a command such as the following:

Virtual ADX(config)#server reassign-threshold 215

Syntax: server reassign-threshold threshold-value

The range of values for the threshold-value variable is 6 through 4000. If you do not specify a number, the Brocade Virtual ADX assigns a default threshold value of 20.


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NOTE

It is possible to take a service down without triggering the reassign threshold. For example, if no new

TCP SYN packets are being sent to a real server that has its application disabled, the real server will not fail to respond to enough consecutive TCP SYNs to meet the reassign threshold. As a result, the

Brocade Virtual ADX indicates the real server and the service are ACTIVE when in fact they might have been disabled.

NOTE

The reassign threshold does not apply to servers in Direct Server Return (Direct Server Return) configurations. The reassign counter is not incremented in such configurations. In a Direct Server

Return configuration, traffic from the real server does not pass back through the Brocade Virtual

ADX. As a result, the Brocade Virtual ADX cannot monitor the TCP SYN ACKs from the server. Refer to

“Configuring Direct Server Return” on page 57.

NOTE

The Brocade Virtual ADX does not try to reassign the client’s request to another server if you configure the application port to be sticky. The sticky option configures the Brocade Virtual ADX to override load-balancing and send all client requests for the application to the same server during a given session.

NOTE

If a real server seems to be triggering the reassign threshold too frequently, you can increase the reassign threshold. This is a global parameter.

Preventing state flapping

You can prevent state flapping caused by the reassignment counter.

By default, the Brocade Virtual ADX brings an application port down if the port's reassignment count exceeds the reassign threshold. If an application port's reassign counter exceeds the reassign threshold, the Brocade Virtual ADX marks the port failed. Once the port is marked failed, the port can be re-activated as a result of a successful health check on the port.

In some networks, the reassignment counter can cause needless state flapping of application ports. This occurs if the network conditions cause the counter to frequently reach the threshold and cause the Brocade Virtual ADX to mark otherwise healthy applications as failed. The applications will remain unavailable for the amount of time it takes the Brocade Virtual ADX to send health checks, interpret the results, and activate the application ports in response to successful results.

NOTE

The reassignment count applies to the total number of contiguous (back-to-back) unanswered SYNs from all clients who have sent SYNs to the server.

To prevent state flapping caused by the reassignment counter, enter the following command.

Virtual ADX(config)#server no-reassign-count

When you enter this command, the Brocade Virtual ADX will stop incrementing the reassignment counters for real server applications.

Syntax: [no] server no-reassign-count


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Globally disabling all health-check policies

You can easily disable all the health-check policies configured on the Brocade Virtual ADX. To do so, enter the following command at the global CONFIG level of the CLI.

Virtual ADX(config)#no server l4-check

NOTE

This command also disables the TCP and UDP Layer 4 health checks for all applications that are not associated with a health-check policy.

Syntax: [no] server l4-check

To re-enable the health-check policies, enter the following command.

Virtual ADX(config)#server l4-check

NOTE

The server l4-check command does not enable a policy if its element-action expressions contain the disable command. In this case, the policy remains disabled.

Health checking for real servers in other subnets

The Brocade Virtual ADX must be able to receive the real server’s response to a health check in order to assess the success of the health check. In topologies where reply traffic from a real server is guaranteed to pass through the Brocade Virtual ADX, the Brocade Virtual ADX is able to receive replies to the health checks.

However, if the topology is such that the Brocade Virtual ADX and real servers are in different subnets or the server reply is not guaranteed to pass back though the Brocade Virtual ADX, you might need to use source NAT and configure a source IP address. Source NAT and source IP addresses allow the Brocade Virtual ADX to have multiple subnet identities. Generally, the Brocade

Virtual ADX is a member of only one subnet, the subnet that contains the Brocade Virtual ADX’s management IP address. You can place the Brocade Virtual ADX into up to eight additional subnets by enabling source NAT and adding source IP addresses to the Brocade Virtual ADX.

Normally, the Brocade Virtual ADX uses its management IP address as the source address for health check packets. When you enable source NAT and add a source IP address, the Brocade

Virtual ADX uses the source IP address as the source for the health check packets. Thus, when the real server replies, the reply is addressed to the source IP address instead of the Brocade Virtual

ADX’s management IP address.

Best path to a remote server

NOTE

Brocade recommends that you use this feature whenever the Brocade Virtual ADX is in the direct path between the remote server and the default gateway.

When the Brocade Virtual ADX sends a health check to a remote server, the Brocade Virtual ADX sends the health check through the default gateway, because the remote server’s subnet is different from the subnet of the Brocade Virtual ADX’s management IP address. In some topologies, the Brocade Virtual ADX’s default gateway is not the most direct path to the remote

server. Figure 24

shows an example.


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FIGURE 24 Health check of remote server – learned MAC address is not used

In this example, the Brocade Virtual ADX sends the health check through its default gateway. The default gateway sends the health check back to the Brocade Virtual ADX, because Router R1’s route to the remote server lists the Brocade Virtual ADX as the next hop. Despite the unnecessary trip through the default gateway, the health check still reaches the remote server. However, if you want to eliminate unnecessary hops, you can enable the Brocade Virtual ADX to learn the MAC address from which the remote server’s health check reply is received, and send subsequent

health checks directly through that MAC address. Figure 25 shows the simplified health check

process.

FIGURE 25 Health check of remote server – learned MAC address is used

To enable the Brocade Virtual ADX to use learned MAC addresses for sending health checks to remote servers, enter the following command.

Virtual ADX(config-rs-remote1)#use-learned-mac-address

Syntax: [no] use-learned-mac-address

NOTE

This command does not apply to local servers. Because local servers are attached at Layer 2, the

Brocade Virtual ADX does not need to use a gateway or otherwise route the health check to the server.

Handling traffic initiated from remote server

Under normal conditions, traffic is always initiated from a client and return traffic is processed by looking up the session table. However, a real server may have to initiate traffic to a client in some complex protocols such as Active FTP. The Brocade Virtual ADX checks the source MAC to handle the traffic initiated from the remote server.

To enable the Brocade Virtual ADX to check the source IP instead of source MAC to handle the traffic from a remote server, enter the following command:

Virtual ADX(config)#server identify-server-by-ip


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Syntax: [no] server identify-server-by-ip

Health check of multiple websites on the same real server

If you host multiple websites on the same real server, with each website using a different VIP, you can perform an independent health check for each VIP.

One method for binding two VIPs to the HTTP port on the same real server, you create an alias for the HTTP port on one of the VIPs. To create an alias for the HTTP port, you configure the VIP to bind to an alternate port number on the real server, then disable port translation for that binding. The

Brocade Virtual ADX collects and presents information for the alias port number, but traffic from both VIPs actually goes to the HTTP port on the real server.

The state of the master port is used for indicating the health of ports aliased to the master port. For example, if a VIP uses port 81 as an alias for the HTTP port, then the state information reported for the HTTP port is used as the state information for port 81. If the HTTP port is reported down, then port 81 is reported down.

When a real server supports multiple websites, tying the alias port's state to the master port's state can cause incorrect information to be reported. For example, consider a real server hosting VIPs v1 and v2. VIP v1 is bound to the HTTP port on the real server, and VIP v2 uses port 81 as an alias for the HTTP port. The Layer 7 health check reports state information about the HTTP port. When VIP v1 is taken down for maintenance, the Layer 7 health check reports that the HTTP port is down.

Because the state information reported for the HTTP port is also used as the state information for port 81, the Brocade Virtual ADX considers port 81 to be down as well, incorrectly reflecting the state of VIP v2, which could be functioning normally.

To eliminate this problem, you establish separate health checks for the alias ports. Health checks for the alias ports will continue to be performed regardless of the HTTP port's status. The following is an example of this kind of configuration.



Virtual ADX(config-vs-v1)#bind http rs32 http




Virtual ADX(config-vs-v2)#port http use-alias-port-state

Virtual ADX(config-vs-v2)#no port http translate

Virtual ADX(config-vs-v2)#bind http rs32 81




Virtual ADX(config-rs-rs32)#port http keepalive

Virtual ADX(config-rs-rs32)#port http url "HEAD /"



Virtual ADX(config-rs-rs32)#port 81 url "GET /81keepalive.htm"


In this configuration, two VIPs are bound to a single real server. VIP v2 uses port 81 as an alias for port 80; information the Brocade Virtual ADX receives about port 81 is attributed to VIP v2. If VIP v1 is taken down for maintenance, the Layer 7 health check done for port 80 fails, and the Brocade

Virtual ADX marks the HTTP port FAILED. However, health checks continue to be performed for port

81. Port 81 (and thus VIP v2) will continue to be reported active as long as it passes its health check.


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Minimum healthy real servers under VIP port

The minimum healthy servers feature allows a VIP port to handle traffic only if the a configured number of real server ports bound to the VIP port are healthy and UP. This would allow virtual servers to stay down unless they have enough server capacity to handle the load.


The command to turn on minimum healthy servers feature is under virtual server configuration.


Virtual ADX(config-virtual-server-v1) port 80

Virtual ADX(config-virtual-server-v1) port 80 minimum-servers 2

Virtual ADX(config-virtual-server-v1) bind http rs1 http rs2 http rs3 http rs4 http

The VIP will not answer connections on port http until at least 2 of the real or remote servers bound to port http are UP.

Server port bring-up enhancement

The Brocade Virtual ADX currently brings a port up after it passes the configured health-check. This feature allows user to configure retries for bringup, so that the Brocade Virtual ADX brings up a port only after the configured number of retries have passed. The real server port will need to pass the configured number of checks before coming up.


The command to turn on server port bring-up enhancement feature is under port profile configuration.


Virtual ADX(config-port-80) bringup-retries 10

The Brocade Virtual ADX will now bring port 80 up only after it has passed the number variable of health-checks. Previously port 80 would have been marked as up after the first time it passes a health-check.

Slow-start mechanism

When the Brocade Virtual ADX begins sending client requests to a real server that has recently gone online, it allows the server to ramp up by using the slow-start mechanism. The slow-start mechanism allows a server (or a port on the server) to handle a limited number of connections at first and then gradually handle an increasing number of connections until the maximum is reached.

The Brocade Virtual ADX uses two kinds of slow-start mechanisms:

• The non-configurable server slow-start mechanism applies to a real server that has just gone online

• The configurable port slow-start mechanism applies to individual TCP application ports that have just been activated on a real server


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Overview

The Brocade Virtual ADX uses the server slow-start mechanism to adjust the maximum number of connections that can be established for a real server that has just gone online. The Brocade Virtual

ADX begins with a connection limit that is lower than the maximum configured value (which is one million by default) and gradually increases this connection limit until the maximum configured value is reached.

The server slow-start mechanism is especially useful when least connections is the distribution predictor. Without the server slow-start mechanism, a server that is just brought online could receive all the new connections in a flurry, which could bring the server down. Many servers cannot handle more than 2,000 new connections per second.

NOTE

The server slow-start mechanism is always applied to all real servers when they are brought online.

Unlike the slow-start mechanism for individual ports, described in the next section, the server slow-start mechanism is not configurable.

The two graphs in Figure 26 illustrate how the server slow-start mechanism ramps up the

connections for a real server during the 30-second slow-start period. The graph on the left shows the rate at which the number of connections increases over the slow-start period. The graph on the right shows how the maximum number of connections that the Brocade Virtual ADX allows for the real server increases over the slow-start period.

FIGURE 26 Slow-start mechanism for a real server

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The graph on the left shows the rate at which the Brocade Virtual ADX allows connections for a given real server, as follows:

• From the time the real server is brought online from 10 seconds to 20 seconds, the Brocade

Virtual ADX allows a max-connection rate of 10 times the elapsed time. During this period, the

Brocade Virtual ADX increases up to 10 new connections every second on the real server.


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• At 21 seconds,the Brocade Virtual ADX allows a max-connection rate of 20 times the elapsed time. The Brocade Virtual ADX increases the connections to 420 and from 22 seconds to 29 seconds, the Brocade Virtual ADX allows up to 20 new connections every second.

• At 30 seconds, the maximum number of connections is reached.

The graph on the right shows how the maximum number of connections allowed for the real server increases over the 30-second slow-start period.

Table 21

lists the maximum number of connections a real server can have during each second of the slow-start period.

TABLE 21 Maximum number of connections for a real server

Seconds after going online Max. connections Seconds after going online

10

11

12

13

6

7

8

9

14

15

3

4

5

1

2

100

110

120

130

60

70

80

90

140

150

10

20

30

40

50

25

26

27

28

21

22

23

24

29

30

16

17

18

19

20

Max. connections

160

170

180

190

200

500

520

540

560

420

440

460

480

580

Maximum

When the slow-start period ends after 30 seconds, the maximum number of connections a real server can have is determined by the max-conn setting for the real server and is one million connections by default.

NOTE

When you disable and re-enable a real server, the Brocade Virtual ADX will go through the slow-start mechanism for the server if it is not disabled. When you disable and re-enable a real-server port, the

Brocade Virtual ADX does not go through the port level slow-start mechanism.

Port slow-start mechanism

When individual TCP application ports on a real server are activated, they are allocated connections using the port slow-start mechanism, which works differently from the server slow-start mechanism described in the previous section.


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When a port on a real server becomes active, the Brocade Virtual ADX applies the default slow-start mechanism to regulate how quickly connections for the port are established. In addition, you can set up a user-configured slow-start mechanism that regulates how quickly connections are established for specific ports on specific real servers. The following sections explain how the default slow-start mechanism works, along with how to set up a user-configured slow-start mechanism and apply it to a port on a real server.

Default port slow-start mechanism

By default, when a port is activated, the Brocade Virtual ADX gives it 60 seconds of warm-up time.

Over this period, the Brocade Virtual ADX gradually increases the number of connections it allows for the port. The default slow-start mechanism is always applied to all ports when they are first brought online, unless they are configured to use a user-configured slow-start mechanism.

The two graphs in Figure 27

illustrate how the default slow-start mechanism ramps up the connections for a port on a real server. The graph on the left shows the rate at which the number of connections increases over the slow-start period. The graph on the right shows how the maximum number of connections the Brocade Virtual ADX allows for the port on the real server increases over the slow-start period.

FIGURE 27 Default slow-start mechanism for a port

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The graph on the left shows the rate at which the Brocade Virtual ADX allows connections for a given port on a real server, as follows:

• At the time the port is activated, the Brocade Virtual ADX allows 10 connections. Then, up to

10 seconds, the Brocade Virtual ADX allows the port up to 10 new connections every second.

• From 10 seconds to 20 seconds, the Brocade Virtual ADX allows up to 20 new connections every second.



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• After 60 seconds, the connection flow control delivered by the slow-start mechanism ends, and the Brocade Virtual ADX allows up to the maximum number of connections for the port on the server. The maximum number of allowed connections for a real server is set by the max-conn command; this maximum is one million connections by default.

The graph on the right shows how the maximum number of connections allowed for the port on the real server increases over the slow-start period.

Table 22 lists the maximum number of connections a port can have at 10-second intervals.

TABLE 22 Maximum number of connections for a port

Seconds after port activated Max. connections

10

20

30

40

50

60

110

310

610

1,010

1,510

2,510

When the slow-start period ends after 60 seconds, the maximum number of connections that a port on a real server can have is determined by the max-conn setting for the real server and is one million connections by default.

Setting up a user-configured port slow-start mechanism

You can configure how quickly the Brocade Virtual ADX ramps up a particular port on a particular real server by setting up a user-configured slow-start mechanism. Unlike the default port slow-start mechanism, which applies to all ports on all real servers, a user-configured slow-start mechanism is applied to a specific port on a specific real server.

A user-configured slow-start mechanism sets the rate at which the Brocade Virtual ADX allows connections for a port over two configurable intervals (which comprise the slow-start period), along with a limit for the total number of connections that the port on the real server can have during the time the server is active.

Setting up a user-configured slow-start mechanism consists of the following two steps.

1. Setting up a slow-start list for a port

2. Applying the slow-start list to a port on a real server

Setting up a slow-start list for a port

To set up a slow-start list for port 80 (HTTP), enter commands such as the following.


Virtual ADX(config-port-80)#slow-start 101 10 30 20 30 600

Virtual ADX(config-port-80)#exit


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Syntax: slow-start list-id rate1 interval1 rate2 interval2 max-connections

In the slow-start command, the list-id variable specifies the slow-start list. This variable can be a number from 1 through 1000000. When you apply the slow-start list to a port on a real server, you refer to the slow-start list by the variable specified here. You can create multiple slow-start lists for a given port and assign them each an ID number.

The rate1 variable specifies the number of connections per second allowed for the port during the first interval. This variable can be a number from 1 through 1000000. From the time the port is activated until the end of the first interval, the Brocade Virtual ADX allows the port on the real server to receive up to this number of new connections every second.

The interval1 variable specifies the length of the first interval in seconds. This variable can be a number from 1 through 1000000.

The rate2 variable specifies the number of connections per second allowed for the port during the second interval. Allowed values are from 1 through 1000000. From the end of the first interval until the end of the second interval, the Brocade Virtual ADX allows the port on the real server to receive up to this number of new connections every second.

The interval2 variable specifies the length of the second interval in seconds. This variable can be a number from 1 through 1000000. The number of seconds in the first interval plus the number of seconds in the second interval are equal to the slow-start period. In this example, value specified for the interval1 variable is 30 seconds, and the value specified for the interval2 value is 30 seconds, so the slow-start period is 60 seconds.

The max-connections variable sets a ceiling for the number of concurrent connections allowed for the port during the time the server is active. This can be a number from 1 through 1000000. No more than this number of connections can be established for the port on the real server where this slow-start mechanism is applied.

Applying the slow-start list to a port on a real server

After you have created a slow-start list, you apply it to a port on a real server, by entering commands such as the following.



Virtual ADX(config-rs-rs1)#port http slow-start 101


Syntax: port port slow-start list-id

The port http slow-start 101 command binds slow-start list 101 (defined for port 80 above) to port

80 (HTTP) on real server rs1.


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Using the slow-start list defined above, the two graphs in Figure 28 illustrate how a user-configured

slow-start mechanism ramps up the connections for a port on a real server. The graph on the left shows the rate at which the number of HTTP connections increases over the slow-start period. The graph on the right shows how the maximum number of HTTP connections the Brocade Virtual ADX allows for real server rs1 increases over the slow-start period.

FIGURE 28 Example of a user-configured slow-start mechanism for port 80 (HTTP) on a real server

The graph on the left shows the rate at which the Brocade Virtual ADX allows HTTP connections for real server rs1, as follows:

• From the time port 80 (HTTP) on real server rs1 is activated until 30 seconds afterwards (until the end of interval 1), the Brocade Virtual ADX allows the real server up to 10 (rate 1) new HTTP connections every second.

• From 30 seconds to 60 seconds (until the end of interval 2), the Brocade Virtual ADX allows up to 20 (rate 2) new HTTP connections every second.

• After 60 seconds (interval 1 plus interval 2), the slow-start period ends, and the Brocade

Virtual ADX allows up to the maximum number of connections for the server set by the max-connections variable in the slow start list.


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The graph on the right shows how the maximum number of possible HTTP connections for real server rs1 increases over the slow-start period:

• Ten seconds after going online, the maximum number of HTTP connections real server rs1 can have is 300: a maximum of 10 (rate 1) new HTTP connections per second for 30 (interval 1) seconds equals 300 total HTTP connections for real server rs1.

• After 30 seconds, the maximum number of HTTP connections for real server rs1 increases by

20 (rate 2) connections per second, until 600 HTTP connections (the ceiling specified by the max-connections variable in the slow-start list) is reached. This ceiling of concurrent 600 HTTP connections applies for the entire time the server is active; the Brocade Virtual ADX allows the server no more than this number of concurrent HTTP connections.

Applying a user-configured slow-start mechanism to multiple ports

To apply a user-configured slow-start mechanism to more than one port, create slow-start lists for each port and apply them to ports on one or more real servers. For example, to configure a slow-start mechanism for HTTP (port 80) and SSL (port 443), enter commands such as the following.

Virtual ADX(config) #server port 80














Virtual ADX(config-rs-rs3)#port ssl

Virtual ADX(config-rs-rs3)#port ssl slow-start 101


The commands create two slow-start lists for port 80 (HTTP) and one for port 443 (SSL). Slow-start list 100 for port 80 is applied to the HTTP port on real server rs2. Slow-start list 101 for port 80 is applied to the HTTP port on real server rs3. Slow-start list 101 for port 443 is applied to the SSL port on real server rs3. Note that slow-start list 101 for port 80 has no relation to slow-start list 101 for port 443.

In this configuration, port 80 on real server rs2 and ports 80 and 443 on real server rs3 are each subject to a user-configured slow-start mechanism. All other ports on the real servers are subject to

the default slow-start mechanism described in “Default port slow-start mechanism” on page 228.

Globally disabling or re-enabling the slow-start mechanism

You can globally disable the mechanism. When you disable the slow-start mechanism, the Brocade

Virtual ADX can immediately send up to the maximum number of connections specified for the real server when the server becomes available. Disabling slow-start does not remove the slow-start configuration information from the real servers.

To re-activate slow-start, globally disable the feature.

Virtual ADX(config)#server no-slow-start


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To globally re-enable slow-start, enter a command such as the following.

Virtual ADX(config)#no server no-slow-start

Syntax: [no] server no-slow-start

FIN close for server health check

FIN close replaces the RESET close for a TCP health check. To enable FIN close, use the following command.

Virtual ADX(config)#server keepalive-fin

Syntax: [no] server keepalive-fin

Health-check state

When you attach a health-check policy to a real server’s application port, the Brocade Virtual ADX uses the health-check policy for periodic health checks and also for the next initial bringup of the server. When a health-check policy is attached, the Brocade Virtual ADX no longer uses the default health check methods for initial bringup and periodic health checks.

For the Brocade Virtual ADX to use a health-check policy, you must enable health checking

(keepalive) at either the port profile level or the real server level for the server port. Otherwise, the state of the policy is FALSE, and the state of the server port remains in the state that it was before you attached the policy.

NOTE

Use the show healthck command to display the policy state. Use the show server real-name name command to show the real server port state.

If health checking for a server port is disabled at the port profile level and at the real server level, the Brocade Virtual ADX will continue to use whichever state is based on the health check during the initial server bringup. The Brocade Virtual ADX will not be able to update the port’s state if the state changes.

To enable health checking at the port profile level, enter commands such as the following.


Virtual ADX(config-port-80)#tcp keepalive enable

These commands enable health checking for TCP port 80.

For a UDP port, enter commands such as the following.


Virtual ADX(config-port-53)#udp keepalive enable

To enable health checking at the real server level, enter commands such as the following.


Virtual ADX(config-rs-R1)#port 80 keepalive

You can enable health checking at the port profile level, at the real server level, or both. Health checking must be enabled on at least one of these levels for the Brocade Virtual ADX to use the health-check policy you attach to the port.


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Enhanced server bringup

Enhanced Server Bringup increases the speed of the bringup process by sending more (up to a maximum of 50) health-checks at one time.

In previous releases, the Brocade Virtual ADX sent a health check for each real server port in a configuration, in the process of bringing up all of the ports. As a result, if the configuration contained many real server ports, the Brocade Virtual ADX would take too much time to bring all of the ports up, one port at a time. To make the bringup process faster, the Brocade Virtual ADX now sends more bringup health-checks at a time (up to a maximum of 50). The actual number of health-checks that the Brocade Virtual ADX sends at any given instance depends on the number of server ports that are in the testing state. The Brocade Virtual ADX performs Layer 2 and Layer 3 health checks, and if these are successful, it puts the port in a testing state. When it is time to send out bringup health checks, the Brocade Virtual ADX collects all the server ports that are in the testing state, and sends them health checks.

The actual number of health checks that are sent out at any given instance also depends on the number of server ports for which the Brocade Virtual ADX has sent out the health-check request and is still waiting for response. For example, if there are 75 server ports configured on the

Brocade Virtual ADX, and at the first instance 30 of these have passed the Layer 2 and Layer 3 checks, the Brocade Virtual ADX sends out bringup health-checks to these 30 server ports. In the next 100 ms, when it is time to send out health-checks again, if only 20 of the above 30 server ports have responded and are UP, then there are 10 ports that are still in the bringup process.

Assuming that the remaining 45 server ports have all passed Layer 2 and Layer 3 checks, the

Brocade Virtual ADX can send bringup health-checks for 40 server ports, because it is waiting for response for the 10 previously sent. In the next 100 ms cycle, it is time to send the next round of health-checks. At this point, if the Brocade Virtual ADX got responses from all the 50 server ports, it now sends bringup health-checks for the remaining five server ports. The Brocade Virtual ADX can send 50 bringup health-checks at a time separately for TCP and UDP ports.

Track-Port support under real server for health checks

The feature allows tracking of several secondary ports based on the health of the primary port.

These secondary ports can be TCP or UDP ports.

Overview

When a group of ports are configured as part of a track-port, the Brocade Virtual ADX can track the health of the master port (the port that is configured as the first port) and the rest of the ports in the track-port list will follow the state of the master port.

If the master port is down, the remaining ports in the track-port list would have their master state as down and traffic will not get forwarded to any of the ports on the track-port list, even though their individual health-checks state might be UP.

Configuration

To turn on this feature, use the hc-track-port which is under the real server configuration as shown:



Virtual ADX(config-real-server-r1) port ftp

Virtual ADX(config-real-server-r1) port dns

Virtual ADX(config-rsr1) hc-track-port 80 21 53


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The Brocade Virtual ADX now tracks the health status of port 80. If the health-check state of port

80 is DOWN, then all the other ports in the track-port list will have their health-check state as also

DOWN. In this case, FTP and DNS have their master state as DOWN and traffic is not load balanced on these ports.

Syntax: [no] hc-track-port port ...

port

The port variable specifies the secondary ports that will be tracked based on the health of the primary port. These secondary ports can be TCP or UDP ports.

Show Commands

The output from the show hc-track-port-state command displays when a primary port passed or failed a health check. Two examples are shown below:

Virtual ADX#show hc-track-port-state

Real Server track-port state rs1 80 21 800 53 ACTIVE

Virtual ADX#show hc-track-port-state

Real Server track-port state rs1 80 21 800 53 DOWN

In the first example above, the primary port passed the health check while in the second example, the primary port went down because of a failed health check.

NOTE

The output above may be truncated. For a complete output display, use the show hc-track-port-state detail command.

Syntax: show hc-track-port-state


Syslog for health status change

The Brocade Virtual ADX generates Syslog messages for changes to the Layer 4 or Layer 7 status of a real server. To display the Syslog buffer on the Brocade Virtual ADX, enter the following command.

Virtual ADX(config)#show logging

Dynamic Log Buffer (50 entries):

03d02h47m38s:N:L4 server 192.168.1.170 danPC is down

03d02h46m18s:N:L4 server 192.168.1.170 danPC is up

03d02h46m08s:I:Interface ethernet5, state up

This example shows log entries for a real server named "danPC" with IP address 192.168.1.170. In this example, the real server passed a Layer 4 or Layer 7 health check ("up"), but then failed a

Layer 4 or Layer 7 health check ("down") later.

Syntax: show logging


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NOTE

The log messages do not distinguish between Layer 4 and Layer 7 health checks. When the status changes based on either type of health check, the Brocade Virtual ADX logs the event as shown in this example.

Session table parameters

The Brocade Virtual ADX maintains state information for TCP and UDP connections in the session table. The session table contains an entry for each TCP and UDP session between the Brocade

Virtual ADX and a client or real server. The Brocade Virtual ADX uses the session table entries for health checks, stateful failover in hot-standby configurations, and other functions.

Each entry in the session table is a session. A session consists of the following:

• Source IP address

• Source application port

• Destination IP address

• Destination application port

• Protocol (TCP or UDP)

A connection consists of two sessions, a send session and a receive session. For example, a TCP connection between a client and a server consists of two sessions, a client-to-server session and a server-to-client session.

NOTE

"Stateless" features such as stateless application ports and stateless health checks do not use session table entries.

This section describes how to configure the following session table parameters:

• Maximum number of sessions

• Maximum age of TCP session entries

• Maximum age of UDP session entries

• Clock scale for TCP and UDP session age timers

• Logging of session table entries

Configuring the maximum number of active sessions

An active session is a session entry in the Brocade Virtual ADX session table. A UDP or TCP session that has become idle, but has not yet timed out (according to the UDP or TCP age timer), is an active session in this table.

To configure the maximum number of active sessions on a Brocade Virtual ADX, use the following command.

Virtual ADX(config)#server session-asm-limit 50000

Syntax: server session-asm-limit value

The value variable specifies the maximum number of active sessions on a Brocade Virtual ADX.

This value can range from 32768 to 4,000,000. The default value is 2,000,000.


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For this change to take effect, you must save the change to the startup-config file, then reload the software using the following commands.

Virtual ADX(config)#write memory

Virtual ADX(config)#end

Virtual ADX#reload

Configuring fast session aging

The Brocade Virtual ADX supports fast session aging. When fast session aging is enabled with the server session-max-idle command, the Brocade Virtual ADX can rapidly age out sessions when the number of available free sessions drops below specified threshold values.

The threshold values are specified as percentages of the maximum number of sessions available on the Brocade Virtual ADX (the "max-sessions" value). The number of free sessions that trigger fast session aging is calculated using the following formula.

number of free sessions = (max-sessions * threshold) / 100

For example, if the max-sessions value on the Brocade Virtual ADX is 500,000 sessions, and the threshold is 30%, then fast session aging is triggered when the number of free sessions reaches

150,000 or fewer; that is (500,000 * 30) / 100.

Two thresholds can be configured for fast session aging: the fast-age threshold and the random threshold:

• Fast-age threshold—When the number of free sessions drops below the fast-age threshold, sessions older than a specified time are aged out.

• Random threshold—When the number of free sessions drops below the random threshold, sessions are aged out randomly, without regard to session age. The random threshold can be equal to or lesser than the fast-age threshold.

For example, if the fast-age threshold is reached, sessions as old as or older than a specified amount of time (for example, 5 minutes) are aged out until the number of available sessions climbs above 150,000. If the random threshold is reached, sessions are aged out at random until the number of available sessions climbs above 150,000.

Fast session aging is disabled by default. To configure fast session aging, enter a command such as the following.

Virtual ADX(config)#server session-max-idle 5 30 10

Syntax: [no] session-max-idle max-idle-time [ fast-age-threshold random-threshold ]

The max-idle-time variable specifies the number of minutes allowed for idle sessions when a fast-age-threshold variable is configured. When the value specified in the fast-age-threshold variable is reached, sessions that are the same as and older than the threshold are aged out until the number of free sessions exceeds the value specified in the fast-age-threshold variable. The value of the max-idle-time variable can be from 1 through 30 minutes. The default is 0 minutes

(disabled). To enable fast session aging, you must specify a value for the max-idle-time variable that is greater than 0.

When the number of available sessions drops below the value specified in the fast-age-threshold variable, sessions older than the value specified in the max-idle-time variable are aged out until the number of free sessions exceeds the threshold. The value of the fast-age-threshold variable is expressed as a percentage of the maximum number of sessions available on the Brocade Virtual

ADX. The value specified for the fast-age-threshold can be from 10 through 70 percent. The default is 33 percent.


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When the number of available sessions drops below the value specified for the random-threshold variable, sessions are aged out randomly, without regard to session age, until the number of free sessions exceeds the threshold. The value specified for the random-threshold variable is expressed as a percentage of the maximum number of sessions available on the Brocade Virtual ADX. The value specified for the random-threshold variable can be from 1 through 30 percent. The default is

0 percent (disabled).

NOTE

Even though the max-idle-time value is not used with the random-age threshold, you must still specify a value for the max-idle-time variable when configuring the random threshold to enable the fast session aging feature.

Displaying information about fast aging

Two fields in the output of the show server sessions command display information about the sessions subject to fast aging.

The following is an example of the output from the show server sessions command. The fields related to fast session aging are highlighted in bold.

Virtual ADX#show server sessions

Avail. Sessions = 524282 Total Sessions = 524288

Total C->S Conn = 0 Total S->C Conn = 0

Total Reassign = 0 Unsuccessful Conn = 0

Fast-aged : total = 0 last 60 sec = 0

Random-aged : total = 0 last 60 sec = 0

Server State - 1:enabled, 2:failed, 3:test, 4:suspect, 5:grace_dn, 6:active

Real Server State CurrConn TotConn TotRevConn CurrSess PeakConn rs1 1 0 0 0 0 0 rs2 1 0 0 0 0 0

Syntax: show server sessions

If the fast-age threshold is configured, the command displays both the total number of sessions that were aged out because of the free sessions dropping below the fast-age threshold, and the number of sessions that were aged out in the last 60 seconds.

If the random threshold is configured, the command also displays the total number of sessions that were aged out at random because the number of free sessions dropped below the random threshold, along with the number of sessions that were aged out randomly in the last 60 seconds.

Clearing statistics counters for fast session aging

To clear the statistics counters for fast session aging, enter the following command.

Virtual ADX(config)#clear server fast-age-counters

Syntax: clear server fast-age-counters

This command resets the "Fast-aged : total" counter and corresponding "last 60 sec" counter as displayed by the show server sessions command.


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Clearing statistics counters for sessions that aged out randomly

If the random threshold is configured, you can clear the statistics counters for sessions aged out randomly, by entering the following command.

Virtual ADX(config)#clear server random-age-counters

Syntax: clear server random-age-counters

This command resets the "Random-aged : total" counter and corresponding "last 60 sec" counter as displayed by the show server sessions command.

Configuring TCP age

The TCP age specifies how many minutes a TCP server connection can remain inactive before the

Brocade Virtual ADX times out the session.

If you change the TCP age, the change affects only new TCP sessions that start after you make the change. The maximum age for sessions that are already in the session table does not change.

NOTE

This parameter globally sets the age for all TCP ports. To override the setting for an individual TCP

port, change that port’s profile. Refer to “Overriding the global TCP or UDP age” on page 192.

To modify the server TCP age, enter a command such as the following.

Virtual ADX(config)#server tcp-age 20

Syntax: server tcp-age time

The time variable is a value from 2 through 60 minutes. The default is 30 minutes.

NOTE

The session age is per minute and has a one minute range. For example, if you configured a TCP age of three minutes, the age timeout is from two to three minutes.

Configuring UDP age

You can modify the aging out parameter for inactive UDP server connections. To modify the server

UDP age to 20 minutes from the default value of 5 minutes, enter a command such as the following.

Virtual ADX(config)#server udp-age 20

This parameter globally sets the age for all UDP ports. To override the setting for an individual TCP

port, change that port’s profile. Refer to “Overriding the global TCP or UDP age” on page 192.

Syntax: [no] server udp-age minutes

The minutes variable is a value from 2 through 60 minutes. The default is 5 minutes; the default age for DNS and RADIUS is 2 minutes.

The Brocade Virtual ADX immediately deletes a UDP DNS or RADIUS session table entry when it receives a reply for the application from a real server. You can configure the Brocade Virtual ADX to age these ports like other UDP ports, using the UDP age timer. Refer to

“Enabling normal UDP aging for DNS and RADIUS” on page 121.


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For DNS and RADIUS UDP load balancing, the age value does not follow the normal configuration and default value unless the udp-normal-age option is configured on the port, under the virtual

server port definition, the port dns udp-normal-age command. (Refer to “Enabling normal UDP aging for DNS and RADIUS” on page 121.) The default UDP age will always be 2 minutes unless the

udp-normal-age option is configured.

Setting the clock scale

The Brocade Virtual ADX uses a configurable clock scale for the following session timers:

• TCP age

• UDP age

To adjust the clock scale for configurations that require TCP or UDP timeouts longer than the maximum configurable value (60 minutes), enter a command such as the following.

Virtual ADX(config)#server clock-scale 2

When you set the clock scale to 2, the TCP and UDP age timer values are multiplied by 2. As a result, a TCP age of 60 would then be equivalent to 120 minutes instead of 60 minutes.

Syntax: [no] server clock-scale multiplier

The multiplier variable can be a value from 1 through 20. The default is 1.

Syslog for session table entries

You can configure the Brocade Virtual ADX to send a message to external Syslog servers when the software creates a session table entry. The messages indicate the following information:

• Source IP address

• Source TCP or UDP application port

• Destination IP address

• Destination TCP or UDP application port

• Layer 4 protocol (TCP or UDP)

• Message time (measured in units of 100 milliseconds, relative to system uptime)

• URL (optional)

• Cookie (optional)

You can enable TCP/UDP logging on a global basis for all TCP and UDP ports or for individual TCP or

UDP ports.

When you enable TCP/UDP logging, you can specify whether all new session table entries generate log messages or only the entries that are used for Source NAT.

In addition, you can enable logging for URL or Cookie information. The URL logging option applies only when URL switching is enabled. The Cookie logging option applies only when Cookie switching is enabled.

Here is an example of a Syslog message for a session.

src-ip = 192.168.002.032 src-port = 00197 dst-ip = 192.168.002.012 dst-port = 00080 protocol = TCP time =0000078656 Url = abcdefghijklmnop

Cookie = qrstuvwxyz


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The time value in this example is in the format for devices on which the system time add date have not been set.

NOTE

The feature description and command syntax use the terms “session” and “connection”. A connection consists of multiple sessions, for the send and receive directions.

NOTE

Because the log messages are generated when the software creates a session table entry, features that do not use session table entries do not result in log messages. For example, if you configure a

TCP or UDP port to be stateless, the Brocade Virtual ADX does not create session table entries for the port and therefore does not generate log messages for the port.

Enabling TCP/UDP session logging

When TCP/UDP session logging is enabled, the Brocade Virtual ADX sends a message to the external Syslog servers when the software creates a session table entry. You can enable session logging globally for all ports or on an individual basis for TCP or UDP ports.

To globally enable logging for all new session table entries, enter the following command.

Virtual ADX(config)#server connection-log all

To enable logging only for new sessions that are used for Source NAT, enter the following command.

Virtual ADX(config)#server connection-log src-nat

To enable session logging for a specific TCP or UDP port, enter the following command.


Virtual ADX(config-port-80)#connection-log all url cookie

Syntax: [no] server connection-log all | src-nat [url] [cookie]

The all option enables logging for all sessions.

The src-nat option enables logging only for sessions that are used for Source NAT.

The url option enables logging of URL information for sessions that contain a URL.

The cookie option enables logging of cookie information for sessions that contain a cookie.

NOTE

The URL logging option applies only when URL switching is enabled. The cookie logging option applies only when cookie switching is enabled.


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Chapter

5

Overview

CSW enables Layer 7 application content based traffic direction for non-HTTP protocols such as

Financial Information Exchange (FIX) protocol. This chapter describes the Layer 7 Switching features in the Brocade Virtual ADX.

•

“Layer 7 content switching” on page 243

•

“Layer 7 content switching on HTTP response” on page 271

NOTE

Fast session synch is not supported in Layer 7 or TCP-offload configurations.

NOTE

You can define up to 255 policies and 1000 rules system wide. A maximum of 500 rules can be defined under a single policy.

NOTE

Layer 7 content switching load balancing is not supported where both sticky connections and track group features are configured.

NOTE


Layer 7 content switching

Layer 7 switching allows the Brocade Virtual ADX to make forwarding decisions about HTTP traffic based on information in a URL, or cookie. Advanced Layer 7 content switching allows the Brocade

Virtual ADX to make forwarding decisions about HTTP traffic by analyzing information contained within the traffic.

The advanced Layer 7 content switching provides an enhancement over the Layer 7 switching feature available in previous Brocade Virtual ADX releases by allowing you to configure load balancing based on multiple HTTP header fields and XML content. The Layer 7 switching feature available in previous releases is limited to load balancing traffic based on hostname, URL, and cookie fields in the HTTP header.

Specifically, the new Layer 7 content switching feature provides the following functionality:

• Load balancing based on any specified HTTP header

• Load balancing based on XML content

• Ability to make complex load-balancing decisions based on multiple HTTP headers or XML tags

• Support for redirecting requests to alternate URLs or domains


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• Support for persisting requests to servers, along with simple forwarding actions

• Support for content-rewrite functions, including cookie and HTTP header insertion and deletion

To configure Layer 7 content switching, you define content switching rules and policies. A rule specifies the content that the Brocade Virtual ADX looks for in the incoming traffic, and a policy associates rules with one or more actions that specify how the Brocade Virtual ADX handles traffic matching the rule.

The following sections explain how to configure Layer 7 content switching on a Brocade Virtual ADX and how to display information about a Layer 7 content switching configuration.

Enabling CSW

To enable Layer 7 content switching, you bind a content switching policy to a virtual server. For example, to enable Layer 7 content switching on a virtual server called cswVIP, enter commands such as the following.

Virtual ADX(config)#server virtual-name-or-ip cswVIP 192.168.20.254

Virtual ADX(config-vs-cswVIP)#port http csw-policy p1

Virtual ADX(config-vs-cswVIP)#port http csw

Syntax: [no] port portnum csw-policy policy-name

Syntax: [no] port portnum csw

The policy-name variable

is a Layer 7 content switching policy. Refer to “Creating a policy” on page 250.

Specifying scan depth

To configure actions based on content carried on top of the HTTP protocol (for example, XML content) you must specify how far into the packet the Brocade Virtual ADX scans for the content.

The Brocade Virtual ADX scans up to the specified limit. If you do not specify a scan depth, then the

Brocade Virtual ADX scans to the end of the packet.

To specify the scan depth for HTTP content, enter commands such as the following:

Virtual ADX(config)#server virtual-name-or-ip cswVIP 192.168.20.254

Virtual ADX(config-vs-cswVIP)#port http csw-scan-depth 128

Virtual ADX(config-vs-cswVIP)#port http csw

Syntax: [no] port portnum csw-scan-depth length

The length variable specifies the number of bytes the Brocade Virtual ADX scans for content in a packet. You can specify up to 8192 bytes. By default, the Brocade Virtual ADX scans to the end of the packet.

Enabling CSW load balance

In HTTP 1.1, a client can send multiple requests over the same connection. The current behavior is that Brocade Virtual ADX regards all requests as independent requests, namely it uses the load balance predictor to perform server selection for each request. This is true even where the next request from the client's connection goes to the same server group. After server selection, this request may go to a different real server within the same server group. This can introduce the extra delay for the client because it needs to establish a new connection for the new real server. If the next request from the same client connection is forwarded within the same server group, the


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Brocade Virtual ADX will not run the server load balance predictor algorithm to choose a new server. It will just use the same real server for the current request. If the next request goes to a different server group, the Brocade Virtual ADX will follow the current code behavior to perform server section.

The following command enables use of a load balancing predictor.

Virtual ADX(config)#server csw request-load-balance

Syntax: [no] server csw request-load-balance

Use the no option if you have previously enabled the command and want to remove it.

When you configure the server csw request-load-balance command, if the client sends two requests to the Brocade Virtual ADX in the same connection and these two requests are switched to the same group, CSW performs server selection based on load balance predictor. If you do not configure this command, CSW uses the same server used by the first client request for the second request.

NOTE

The server csw request-load-balance command is only applicable to keep-alive and TCP-offload mode.

CSW rules

This section describes the rules available for Layer 7 content switching. You can define the following types of rules:

• HTTP method rules – Cause the Brocade Virtual ADX to make a load balancing decision based

on the HTTP method in an incoming packet. Refer to “Configuring an HTTP method rule” on page 245.

• HTTP version rules – Cause the Brocade Virtual ADX to make a load balancing decision based

on the HTTP version of an incoming packet. Refer to “Configuring an HTTP version rule” on page 246.

• URL rules – Cause the Brocade Virtual ADX to make a load balancing decision based on the

contents of the URL string in an incoming packet. Refer to “URL rules” on page 246.

• HTTP header rules – Cause the Brocade Virtual ADX to make a load balancing decision based on the contents of an HTTP header field in an incoming packet. Refer to

“HTTP header rules” on page 247.

• XML tag rules – Cause the Brocade Virtual ADX to make a load balancing decision based on

the contents of an XML tag in an incoming packet. Refer to “XML tag rules” on page 248.

NOTE

For CSW rules that use the prefix or suffix method, the matching string will be the complete string and the offset is starts from the matching string.

Configuring an HTTP method rule

To set up an HTTP method rule that causes the Brocade Virtual ADX to make a load balancing decision based on the HTTP method in an incoming packet, enter a command such as the following.

Virtual ADX(config)#csw-rule r1 method eq PUT


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This example creates a rule called r1 that matches if an incoming packet contains the PUT method.

Syntax: [no] csw-rule rule-name method eq method-string

The rule-name variable is the name of the rule and can be up to 80 characters in length.

The method-string variable can be GET, HEAD, POST, OPTIONS, PUT, DELETE, TRACE, PROPFIND,

MOVE, CONNECT, BDELETE, PROPPATCH, COPY, LOCK, UNLOCK, MKCOL, BCOPY, BMOVE, POLL,

SUBSCRIBE, SEARCH, BPROPPATCH, RPC_OUT_DATA, or RPC_IN_DATA.

Configuring an HTTP version rule

To set up an HTTP method rule that causes the Brocade Virtual ADX to make a load balancing decision based on the HTTP version of an incoming packet, enter a command such as the following.

Virtual ADX(config)#csw-rule r1 version eq 1.1

This example creates a rule called r1 that matches if an incoming packet uses HTTP version 1.1.

Syntax: [no] csw-rule rule-name version eq http-version

The rule-name variable is the name of the rule and can be up to 80 characters in length.

The http-version variable can be 0.9, 1.0, or 1.1.

URL rules

URL rules cause the Brocade Virtual ADX to make a load-balancing decision based on the contents of the URL string in an incoming packet.

Table 23 lists the URL rules available for Layer 7 content switching.

TABLE 23 URL rules for Layer 7 content switching

URL rule name

Description Syntax Example

URL Exists

URL Prefix

Matches if a URL string exists in the incoming packet.

Matches if the

URL string begins with the specified prefix.

URL Suffix Matches if the

URL string ends with the specified suffix.

URL Pattern Matches if the specified pattern exists anywhere within the URL string.

[no] csw-rule rule-name url exists

[no] csw-rule rule-name url prefix value

[no] csw-rule rule-name url suffix value

[no] csw-rule rule-name url pattern value csw-rule r1 url exists csw-rule r1 url prefix "/home" csw-rule r1 url suffix ".gif" csw-rule r1 url pattern "test"


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TABLE 23 URL rules for Layer 7 content switching (Continued)

URL rule name


URL Equals Matches if the

URL string is equal to the specified value.

URL Search Matches if the

URL string contains any one of up to five specified values.

This type of rule can be used with the persist action.

[no] csw-rule rule-name url equals value

[no] csw-rule rule-name url search value csw-rule r1 url equals

"/home.html" csw-rule r1 url search "srvr1" csw-rule r1 url search "srvr2" csw-rule r1 url search "srvr3" csw-rule r1 url search "srvr4" csw-rule r1 url search "srvr5"

HTTP header rules

HTTP header rules cause the Brocade Virtual ADX to make a load-balancing decision based on the contents of an HTTP header field in an incoming packet.

In an Layer 7 content switching configuration, you can configure rules for the following HTTP header fields: Connection, Transfer-Encoding, Content-Length, Host, Cookie, Pragma, and Cache-Control, as well as up to 10 other HTTP header fields.

Table 24

lists the HTTP header rules available for Layer 7 content switching.

TABLE 24 HTTP header rules for Layer 7 content switching

HTTP header rule name


Header Exists Matches if the specified HTTP header field exists in the incoming packet.

Header Prefix Matches if the value in the specified HTTP header field begins with the specified prefix.

Header Suffix Matches if the value in the specified HTTP header field ends with the specified suffix.

Header

Pattern

Matches if the specified pattern exists anywhere within the specified HTTP header field.

[no] csw-rule rule-name header header-name exists

[no] csw-rule rule-name header header-name prefix value

[no] csw-rule rule-name header header-name suffix value

[no] csw-rule rule-name header header-name pattern value csw-rule r1 header "host" exists csw-rule r1 header "host" prefix

"www" csw-rule r1 header "host" suffix

"com" csw-rule r1 header "cookie" pattern "Serverid"


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TABLE 24 HTTP header rules for Layer 7 content switching (Continued)

HTTP header rule name


Header

Equals csw-rule r1 header "host" equals

"www.example4.com"

Header

Search

Matches if the contents of the specified HTTP header field are equal to the specified value.

Matches if the specified HTTP header field contains any one of up to five specified values.


[no] csw-rule rule-name header header-name equals value

[no] csw-rule rule-name header header-name search value csw-rule r1 header "cookie" search

"ServerId1" csw-rule r1 header "cookie" search

"ServerId2"

XML tag rules

XML tag rules cause the Brocade Virtual ADX to make a load balancing decision based on the contents of an XML tag in an incoming packet. Rules for up to 200 different XML tags can be specified in an Layer 7 content switching configuration. In a given policy, you can include rules for up to 5 XML tags.

Table 25 lists the XML tag rules for Layer 7 content switching.

TABLE 25 XML tag rules for Layer 7 content switching

XML tag rule name


XML Tag

Exists

XML Tag

Prefix

XML Tag

Suffix

XML Tag

Pattern

Matches if the specified XML tag exists in the incoming packet.

Matches if the value in the specified XML tag begins with the specified prefix.

Matches if the value in the specified XML tag ends with the specified suffix.

Matches if the specified pattern exists anywhere within the specified XML tag.

[no] csw-rule rule-name xml-tag tag-name exists

[no] csw-rule rule-name xml-tag tag-name prefix value

[no] csw-rule rule-name xml-tag tag-name suffix value

[no] csw-rule rule-name xml-tag tag-name pattern value csw-rule r1 xml-tag "name" exists csw-rule r1 xml-tag "name" prefix "ge" csw-rule r1 xml-tag "name" suffix "ge" csw-rule r1 xml-tag "name" pattern "org"


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TABLE 25 XML tag rules for Layer 7 content switching (Continued)

XML tag rule name

Description Syntax

XML Tag

Equals

XML Tag

Search

Matches if the contents of the specified XML tag are equal to the specified value.

Matches if the specified XML tag contains any one of up to five specified values.


[no] csw-rule rule-name xml-tag tag-name equals value

[no] csw-rule rule-name xml-tag tag-name search value

Example csw-rule r1 xml-tag "name" equals "george" csw-rule r1 xml-tag "name" search "geo" csw-rule r1 xml-tag "name" search "edw"

Case-insensitive match for content switching

With Case-Insensitive Match for content switching (CSW you can optionally specify a CSW-rule or

CSW-policy to be case insensitive and the consequent match ignores case for the input.

The following example shows how to configure a case-insensitive rule.

Virtual ADX(config)#csw-rule r1 url pattern /test/index.html case-insensitive

Syntax: csw-rule rule-name url | header | method | xml-tag pattern pattern-to-match

[case-insensitive]

The case-insensitive option specifies the pattern match to be case insensitive.

The following example shows how to configure a case-insensitive policy.

Virtual ADX(config)#csw-policy p1 case-insensitive

Syntax: csw-policy policy-name [case-insensitive]

The case-insensitive option specifies that this policy is case-insensitive.

NOTE

You cannot mix case-insensitive policy and case-sensitive rules, or vice versa.

Wildcards in CSW rules for URL prefixes

Wildcards in CSW rules for URL prefixes behave as described for the following CSW rule: csw-rule "pages0" url prefix "/pages/0*"

In this case, "/pages/0*" does not match on " /pages/0". It would only match on URLs such as

"/pages/01" and "/pages/011119011", where the URL is at least one byte longer that the part of the rule before the asterisk.


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CSW policies

A policy specifies the action to take when a rule is matched. You can specify the following actions in a policy:

• Forward action – Causes the Brocade Virtual ADX to forward packets matching a specified rule to a specified real server or server group. Refer to

“Configuring the forward action” on page 250.

• Reply-error action – Causes the Brocade Virtual ADX to send a 403 error code page back to the client when the specified rule is matched. Refer to

“Configuring the reply-error action” on page 253.

• Log action – Causes the Brocade Virtual ADX to write a message to Syslog when the specified rule is matched. You can optionally customize the format of the Syslog message. Refer to

“Configuring the log action” on page 253.

• Redirect action – Causes the Brocade Virtual ADX to redirect a request to an alternate domain,

URL, or port when the specified rule is matched. Refer to

“Configuring redirect” on page 264.

• Persist action – causes the Brocade Virtual ADX to send requests with similar content to the

same server when the specified rule is matched. Refer to “Configuring the persist action” on page 251.

NOTE

If no rule is matched, traffic is directed to the internet.

NOTE


Creating a policy

To create a policy for Layer 7 content switching, enter a command such as the following.

Virtual ADX(config)#csw-policy policy1

Syntax: [no] csw-policy policy-name

The policy-name variable can be up to 80 characters in length.

Configuring the forward action

The forward action causes the Brocade Virtual ADX to forward packets matching a specified rule to a specified real server or server group.

For example, the following command specifies that packets matching rule r1 be forwarded to real server 1029.

Virtual ADX(config-csw-policy1)#match r1 forward 1029

Syntax: [no] match rule-name forward id [cookie-name name ]

The rule-name variable is the name of a previously configured Layer 7 content switching rule.

The id variable refers to a real server or server group ID. An ID between 0 and 1023 indicates a server group ID, and an is between 1024 and 2047 indicates a real server ID.


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NOTE

The real server ID range is limited to 1024-1+the maximum number of real servers that can be configured on the Brocade Virtual ADX. For example, if the maximum server limit is 16384, then the valid real server ID range is from 1024 to 1024-1+16384=17407.

If you specify a server group ID, you can optionally specify a cookie name. When you specify a cookie name, the Brocade Virtual ADX performs cookie switching on packets matching the rule, which ensures that packets matching the rule go to the same real server within the server group.

Configuring the persist action

The persist action causes the Brocade Virtual ADX to send requests with similar content to the same server when the specified rule is matched. When a rule is matched, the Brocade Virtual ADX uses the content that matched the rule, in combination with a specified persistence method, to select a server or server group to which to send the packet.

When a rule is associated with the persist action, a server or server group is selected as follows.

1. An incoming packet matches a configured CSW rule. For example, a CSW rule matches if an incoming packet contains a cookie header field with the string “ServerID” as shown in the following.

Virtual ADX(config)#csw-rule r1 header "cookie" search "ServerId"

The persist action can then be used in conjunction with the above CSW rule.

2. The Brocade Virtual ADX examines the matched content to determine the persist string. The persist string contains the portion after the matched string that the Brocade Virtual ADX uses,

(along with the persist method) to select a real server (or server group) to which to send the packet.

For example, in CSW rule r1 defined above, the matched content could be something like:

“ServerID=2”

Then, you can specify that the persist string be a segment of the matched content, starting from a specified offset from the matched string (ServerID) and lasting for a specified length. In the example above, if you specify an offset of “1” and a length of “1”, the persist string would be “2”.

3. The Brocade Virtual ADX uses the persist string along with the configured persist method to select a real server or group. By default, the Brocade Virtual ADX uses a hash-to-bucket persist method to select a real server.


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The hash-to--bucket persist method is illustrated in the following figure.

FIGURE 29 Hash-to-bucket persist method

252

For a given rule, you can configure a primary persist action and a secondary persist action. If the primary persist action does not return a valid persist string, or if the server indicated by the primary persist string is not available, the Brocade Virtual ADX uses the secondary persist action to direct packets to a server.

The following commands configure a CSW rule and policy that use the persist action.

Virtual ADX(config)#csw-rule r1 header host exists

Virtual ADX(config)#csw-policy p1

Virtual ADX(config-csw-p1)#match r1 persist offset 0 length 0

In the above example, the csw-rule command creates a rule that matches if an incoming packet contains an HTTP host header field. The csw-policy command creates a policy called p1. The match r1 persist command associates the rule with the persist action. As a result, if an incoming packet has an HTTP host header field, the contents of the host header field are used as the persist string.

The Brocade Virtual ADX uses the persist string along with the default hashing-bucket persist method to calculate the real server to which to send the packet.

Syntax: [no] match rule-name persist offset offset length length [[ persist-method ] [secondary]] or

Syntax: [no] match rule-name persist offset offset terminator string [[ persist-method ] [secondary]]

The offset variable specifies the offset in bytes from the end of the matched string, matched by the rule-name to be used as the persist string. If you specify 0 as the offset , the persist string begins right after the matched string.

The length variable specifies the length in bytes of the persist string. If you specify 0 as the length , the persist string ends at the end of the matched content.

The string variable specifies the substring with which the persist string ends.


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The persist-method variable specifies which of the following persist methods you want to use.

•

hash-to-bucket – Hashes the persist string to a hashing bucket, as illustrated in Figure 29

. This is the default.

• hash-to-group-id – Hashes the persist string to a server group ID, instead of to a hashing bucket.

• group-or-server-id – Translates the persist string to the ID of a real server or server group.

• server-name – Translates the persist string to the name of a real server.

• alias-name – Translates the persist string to the name of an alias.

The secondary keyword indicates that this is a secondary persist action for the rule. If the primary persist action does not return a valid persist string, or if the server indicated by the primary persist string is not available, the Brocade Virtual ADX uses the secondary persist action to direct packets to a server.

NOTE

By configuring both a CSW policy that utilizes the persist action and a TCP or UDP port as sticky, you can implicitly enable persistence fallback . In this scenario, the CSW policy defines the default method of defining persistence. However, If no cookie is detected, the Brocade Virtual ADX falls back to the sticky persistence configured for the address.

Configuring the reply-error action

The reply-error action causes the Brocade Virtual ADX to send a 403 error code page back to the client when the specified rule is matched.

For example, to cause the Brocade Virtual ADX to send a 403 error code page to a client that sent a packet that matched rule r1, enter the following command.

Virtual ADX(config-csw-policy1)#match r1 reply-error

Syntax: [no] match rule-name reply-error

Configuring the log action

The CSW match log action only logs to a log server, not the local log of the Brocade Virtual ADX displayed by the show logging command. You must configure a remote server (per the global logging ip-addr command) to receive the log. The syslog server cannot be connected to the management port because CSW log action is processed by the BP, and the management port is controlled by the MP.

NOTE

The log action requires a primary action forward or persist to be configured.

An example Syslog message follows.

192.168.9.210 80 HTTP Rule matched, Forward

To cause the Brocade Virtual ADX to write a message to Syslog when rule r1 is matched, enter a command such as the following:

Virtual ADX(config-csw-policy1)#match r1 log

Syntax: [no] match rule-name log [ format ]


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By default, the format of the Syslog message is as follows.

source-ipaddr source-port protocol Rule matched, action-message

Additionally, you can change the format of the Syslog message using the following tokens:

• $SIP – Source IP address

• $DIP – Destination IP address

• $SPT – Source port

• $DPT – Destination port

• $HST – Host name

• $URL – URL

• $RUL – Rule name

• $ACT – Action

For example, the following command specifies an alternate format for the Syslog message:

Virtual ADX(config-csw-policy1)#match r1 log "$SIP:$SPT->$DIP:$DPT,ru $RUL hit

$ACT"

In this example, when a packet matches rule r1, a message such as the following is written to

Syslog.

192.168.9.210:80->10.10.10.10:80, ru r1 hit forward

Inserting a cookie

You can configure the Brocade Virtual ADX to insert a cookie into an HTTP response when a specified rule is matched. When the rule is matched, a cookie is inserted in the response when any of the following occur:

• No cookie header is found in the HTTP request, or a cookie header exists but it does not contain the cookie name specified by the rewrite insert-cookie command.

• The specified cookie name is found in the HTTP request, but the cookie value is out of the range used for cookie switching. The cookie value must be between 1 and 17407.

• The specified cookie name is found in the HTTP request, but the real server or server group indicated by the cookie value is not available.

For example, the following command causes the Brocade Virtual ADX to insert the cookie indicated by the rewrite insert-cookie command into the HTTP response when rule r1 is matched.

Virtual ADX(config-csw-policy1)#match r1 rewrite insert-cookie

Syntax: [no] match rule-name rewrite insert-cookie

Deleting a cookie

Cookie deletion causes the Brocade Virtual ADX to delete the cookies that it set. The Brocade

Virtual ADX removes the cookie from the HTTP request prior to sending the request to the server.

For example, the following command causes the Brocade Virtual ADX to delete the cookie indicated by the rewrite insert-cookie command from the HTTP response when rule r1 is matched.

Virtual ADX(config-csw-policy1)#match r1 rewrite delete-cookie

Syntax: [no] match rule-name rewrite delete-cookie


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Damaging a cookie

Cookie damage consists of altering the cookie header so that it does not contain any cookie that matches the name of the cookie inserted by the Brocade Virtual ADX.

For example, the following command causes the Brocade Virtual ADX to damage the cookie indicated by the rewrite insert-cookie command in the HTTP response when rule r1 is matched.

Virtual ADX(config-csw-policy1)#match r1 rewrite destroy-cookie

Syntax: [no] match rule-name rewrite destroy-cookie

Inserting an HTTP header

HTTP header insertion causes the Brocade Virtual ADX to insert a header into the HTTP requests that it receives on a virtual server or into the HTTP responses that it sends out from a virtual server.

The header is specified within the CSW match command using the request-insert parameter (for

HTTP requests) or the response-insert parameter (for HTTP responses).

To cause the Brocade Virtual ADX to insert a standard HTTP “Via:” header into HTTP requests matching rule r1, enter the following command.

Virtual ADX(config-csw-p1)#match r1 rewrite request-insert header "Via:

Brocade

Virtual ADX

"

To cause the Brocade Virtual ADX to insert the header "Brocade Virtual ADX: proto=HTTP+MMS

" into the HTTP responses (matching rule r1) that it sends from the virtual server, enter the following command.

Virtual ADX(config-csw-policy1)#match r1 rewrite response-insert header "

Brocade

Virtual ADX

: proto=HTTP+MMS"

Syntax: [no] match rule-name rewrite response-insert header header

The header variable specifies the string that will be inserted.

Inserting an IP address in a header

HTTP Header insertion can direct the Brocade Virtual ADX to insert the Client IP address into the

HTTP requests it receives on a virtual server that matches a CSW rule you define.

This feature can be useful in situations where Source Network Address Translation (source NAT) is enabled on a Brocade Virtual ADX. With Source NAT enabled, original source IP addresses are translated into one common IP address. As a result, servers are unable to identify clients by their original source IP addresses. In some cases, the real source IP addresses of the clients may be necessary; for example, for server applications to report statistics, or for web administrators who may need to know the real source IP addresses of the clients in order to secure the system.

You can use the HTTP header insertion feature to insert the original source IP address into the

HTTP request. Servers are then able to identify clients by their original source IP addresses.

To cause the Brocade Virtual ADX to insert the IP address of the connecting client into HTTP requests matching rule r1, enter the following command.

Virtual ADX(config-csw-policy1)#match r1 rewrite request-insert client-ip

"MyClientIP"

Syntax: [no] match rule-name rewrite request-insert client-ip header


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Configuring Rewrite request-delete

HTTP URL Rewrite allows the Brocade Virtual ADX to delete a string or portion of a string from inside the incoming client request, as described in the following sections:

•

“Deleting a matched-string” on page 256

•

“Deleting content at positive offset” on page 257

•

“Deleting content at negative offset” on page 258

•

“Deleting a string” on page 259

Deleting a matched-string

To configure a request to delete a matched string in a CSW rule, follow these steps.

1. Define a CSW rule to search for a sub-string in a URL.

Virtual ADX(config)#csw-rule r11 url pattern "-sample"

Syntax: csw-rule rule-name url pattern url-content

2. Define a CSW policy.

Virtual ADX(config)#csw-policy mypolicy

Syntax: csw-policy policy-name

3. Specify a primary action to forward a request to a server with an ID of 1025 when rule r11 is matched.

Virtual ADX(config-csw-mypolicy)#match r11 forward 1025

Syntax: match rule-name forward server-id

4. Specify a dependent action to delete the sub-string -sample when it is found in the URL.

Virtual ADX(config-csw-mypolicy)#match r11 rewrite request-delete matched-string

Syntax: match rule-name rewrite request-delete matched-string

5. Specify a dependent log action.

Virtual ADX(config-csw-mypolicy)#match r11 log

Syntax: match rule-name log

6. Specify a default action.

Virtual ADX(config-csw-mypolicy)#default forward 1026

Syntax: default forward server-id

NOTE

The following information assumes you have already completed the previous configuration.

If the Brocade Virtual ADX were to receive a request for URL /abc/xyz-sample/index.html, it would take the following actions:

• Delete sub-string "-sample" in the URL, which becomes /abc/xyz/index.html.

• Forward the request to Web Server 1.

• Log primary Forward action to the log server.


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In this case, "-sample" is the deleted string that CSW rule r11 matches. The request is forwarded to the server with server ID 1025, which is defined by primary CSW action match r11 forward 1025.

The URLs in the following two HTTP request messages show the difference between the original request and the rewritten request.

If there is no sub-string "-sample" in the URL of the HTTP request, rule r11 is not hit, the request is sent to the server with server ID of 1026, which is defined by the default rule default forward 1026.

Example Original HTTP request:

GET /abc/xyz-sample/index.html

HTTP/1.1\r\n

Host: www.example5.com\r\n

User-Agent: Mozilla/5.0 Netscape/7.02\r\n

Accept-Charset: ISO-8859-1\r\n

Cookie: name=brocadenet; userid=12345\r\n

\r\n

Example Rewritten HTTP request:

GET /abc/xyz/index.html

HTTP/1.1\r\n





\r\n

Deleting content at positive offset

NOTE

For more information about offsets, refer to “Explanation of offsets” on page 265.

To configure a request to delete content at a positive offset, follow these steps.

1. Define a CSW rule to search for a prefix "/abc" in URL.

Virtual ADX(config)#csw-rule r12a url prefix "/abc"

Syntax: csw-rule rule-name url prefix prefix-content




3. Specify a primary action.

Virtual ADX(config-csw-mypolicy)#match r12a forward 1025


4. Specify a dependent rewrite action.

Virtual ADX(config-csw-mypolicy)#match r12a rewrite request-delete offset 4 2

Syntax: match rule-name rewrite request-delete offset offset length

NOTE



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The URL prefix "/abc" is matched, offset 0 is at the second "/", which is right after the matched prefix "/abc" in the URL, which is defined in CSW "r12a"; so offset 4 is number "1" which is 4 bytes away after the letter "c". The result is that the 2 bytes containing "12" are deleted in the URL.


GET /abc/xyz12/index.html

HTTP/1.1\r\n

Host: www.foo.com\r\n




\r\n



HTTP/1.1\r\n

Host: www.foo.com\r\n




\r\n

Deleting content at negative offset

NOTE


To configure a request to delete content at a negative offset, follow these steps.

1. Define a CSW rule to search for the suffix ".html" at end of URL.

Virtual ADX(config)#csw-rule r12b url suffix ".html"

Syntax: csw-rule rule-name url suffix content





Virtual ADX(config-csw-mypolicy)#match r12b forward 1025



Virtual ADX(config-csw-mypolicy)#match r12b rewrite request-delete neg-offset

11 6

Syntax: match rule-name rewrite request-delete neg-offset offset length

NOTE

The following information assumes you have configured the previous scenario.

When ".html" is matched, offset 0 is the white space after letter "l", letter "l" is neg-offset 1, letter

"m" is neg-offset 2, letter "t" is neg-offset 3 and so on. As a result, neg-offset 11 is "_". By counting

6 bytes from left to right starting with "_", you can see that "_index" is to be deleted.


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GET /abc/xyz/default_index.html

HTTP/1.1\r\n





\r\n


GET /abc/xyz/default.html

HTTP/1.1\r\n





\r\n

Deleting a string

NOTE


To configure a request to delete a sub-string in a CSW rule, follow these steps.

1. Define a CSW rule.

Virtual ADX(config)#csw-rule r13 url exists

Syntax: csw-rule rule-name url exists








Virtual ADX(config-csw-mypolicy)#match r13 rewrite request-delete string "123"

Syntax: match rule-name rewrite request-delete string string-content

NOTE


The url-exist matches any URL. If found, only string "123" is deleted; if no instance of "123" is found in the URL, the original URL is sent to the server.


GET /abc/xyz123/index.html

HTTP/1.1\r\n


User-Agent: Netscape/7.02\r\n




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\r\n



HTTP/1.1\r\n





\r\n

Configuring Rewrite request-insert

Content insertion allows the Brocade Virtual ADX to insert any string either right after the matched string found by the CSW rule, or at any specified offset in the content located by the matched CSW rule. Use the following procedures to configure a string insert at a positive offset or a negative offset.

NOTE


Inserting a string at positive offset

To configure a request to insert a string after a CSW rule match, follow these steps.

1. Define a CSW rule for the HTTP prefix of the URL.

Virtual ADX(config)#csw-rule r21 url prefix "/abc"








4. Specify a dependent rewrite string.

Virtual ADX(config-csw-mypolicy)#match r21 rewrite request-insert /hello-world

Syntax: match rule-name rewrite request-insert content offset

NOTE


NOTE

If no offset is defined, the Brocade Virtual ADX will always insert at offset 0.

Offset 0 is at the second "/", which is right after matched prefix "/abc", as defined in CSW "r21".

The result is that the string "/hello-world" is inserted at the default offset 0, which is after letter "c".

The original URL becomes "/abc/hello-world/xyz/index.html".


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The highlighted URLs in the following two HTTP request messages show the difference between the original request and the one after being rewritten.



HTTP/1.1\r\n





\r\n


GET /abc/hello-world/xyz/index.html

HTTP/1.1\r\n





\r\n

Inserting a string at negative offset

To configure a request to insert a string after a CSW rule match, follow these steps.

1. Define a CSW rule for HTTP URL content.

Virtual ADX(config)#csw-rule r22 url prefix /abc/









Virtual ADX(config-csw-mypolicy)#match r22 rewrite request-insert /hello-world neg-offset 5

Syntax: match rule-name rewrite request-insert content neg-offset offset

NOTE


NOTE

If you want to insert a string at the beginning of a URL, make sure that the string always starts with a "/", or the server that receives the request returns a response of "bad request." This response indicates the format is invalid. The assumption is that the URL always starts with a "/".


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The highlighted URLs in the following two HTTP request messages show the difference between the original request and the rewritten request. Offset 0 is at the first "x," which is right after the matched prefix "/ abc/," as defined in CSW "r22". Therefore, negative offset 5 is at the first "/," which is 5 bytes away from and before the "x." The result is that string "/hello-world" is inserted at the first "/", which is the beginning of URL "/abc/xyz/index.html". The original URL becomes

"/hello-world/abc/xyz/index.html".



HTTP/1.1\r\n





\r\n


GET /hello-world/abc/xyz/index.html

HTTP/1.1\r\n





\r\n

NOTE

When inserting a string in an HTTP request, make sure the negative offset is correctly specified.

Incorrectly specifying the negative offset (out of range) may result in an improper HTTP request.

Configuring Rewrite request-replace

Content replacement allows you to replace a defined string, or a string that matches a CSW rule.

The following procedures explain both methods.

Replacing a string defined by content rule

To configure a request to replace a string that matches a CSW rule, follow these steps.


Virtual ADX(config)#csw-rule r31 url exist

Syntax: csw-rule rule-name url exist

2. Define a CSW policy







Virtual ADX(config-csw-mypolicy)#match r31 rewrite request-replace matched-string "/newabc/newxyz/newindex.html"


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Syntax: match rule-name rewrite request-replace matched-string new-string

The rule-name variable defines the name of CSW rule.

The matched-string keyword defines the matched string (defined by CSW rule), which is to be replaced.

The new-string variable defines the new string that replaces the previous string.

NOTE


The url-exist matches the entire URL, so the matched string is the whole URL

"/abc/xyz/index.html." It is replaced by the new string "/newabc/newxyz/newindex.html."



HTTP/1.1\r\n





\r\n


GET /newabc/newxyz/newindex.html

HTTP/1.1\r\n





\r\n

Replace a defined string

To configure a request to replace a specific string in a CSW rule match, follow these steps.


Virtual ADX(config)#csw-rule r32 url pattern "abc"

Syntax: csw-rule rule-name url pattern pattern-content

2. Define a CSW policy






4. Specify a dependent rewrite action

Virtual ADX(config-csw-mypolicy)#match r32 rewrite request-replace string

"xyz" "1234"

Syntax: match rule-name rewrite request-replace string old-string new-string

The rule-name variable defines the name of the CSW rule.


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The old-string variable defines the string to be replaced, if it can be found in the URL defined by the CSW rule. If the old-string variable is not found, the replacement will not happen.

The new-string variable defines the string with which the old string is to be replaced.

NOTE


Because the URL contains the pattern "abc," rule r32 will be hit. Then a search for string "xyz" also is positive, so "xyz" will be replaced with string "1234". The following two HTTP request messages show the difference between the original request and the rewritten request.



HTTP/1.1\r\n





\r\n


GET /abc/1234/index.html

HTTP/1.1\r\n





\r\n

Configuring redirect

The redirect action causes the Brocade Virtual ADX to redirect a request to an alternate domain,

URL, port, or Uniform Resource Identifier (URI) when the specified rule is matched.

For example, the following command causes the Brocade Virtual ADX to redirect a request to the domain brocade.com, URL

/home/index.html, and port 8080 when rule r1 is matched.

Virtual ADX(config-csw-policy1)#match r1 redirect "brocade.com"

"/home/index.html" 8080

Syntax: [no] match rule-name redirect domain [ url | [ port status-code ] | [ url new-port ]]

The rule-name variable can be up to 80 characters in length.

The domain variable can be up to 255 characters.

The url variable can be up to 255 characters.

You can optionally specify

*

(asterisk) for either the domain or url variables. When you do this, the redirected request uses the same domain or URL as in the original request.

For the port variable, you can enter any well-known port name or port number. For the status-code variable, enter any three-digit status code.

For the url new-port variables, enter the new URL and port number to which the request will be redirected.


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HTTP redirect status code

The Brocade Virtual ADX can be configured to use a temporary or permanent move to suit different application requirements:

• 301 - To redirect the HTTP request to a new, assigned permanent URI.

• 302 (the default) -To redirect HTTP requests to a temporary URI.

To redirect an HTTP request with redirect code 301, enter the following command.


Virtual ADX(config-csw-p1)#match r1 redirect "brocade.com" HTTP 301

Explanation of offsets

NOTE

The offset or neg-offset keyword indicates that insertion or deletion starts after or before the offset of the interested content defined in the matched CSW rule.

In this example, the Brocade Virtual ADX receives the following message.

GET /abc/xyz/index.html HTTP/1.1\r\n

Host:www.example5.com\r\n




\r\n

The following examples show how the offsets work for various rules.

Prefix matching csw-rule ruleA url prefix /abc/x

Offset 0 points to "y", which is the next byte after "/abc/x" in the URL.

Suffix matching csw-rule ruleB header Host suffix com

Offset 0 points to "\r", which is the next byte after "com" in the value of "Host" header

"www.example5.com".

Pattern matching csw-rule ruleC header Host pattern foo.

Offset 0 points to "c", which is the next byte after "foo." in the value of "Host" header

“www.example5.com”.

Exist matching csw-rule ruleD1 url exist

Offset 0 points to white space after the letter "l", which is right after the last byte of URL

"/abc/xyz/index.html".

Equal matching csw-rule rule header "Host" equal "www.example5.com"


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Sample configurations

Offset 0 points to "\r", which is the next byte after "www.example5.com" in the value of "Host" header, "www.foo.com".


The HTTP URL Rewrite feature allows the Brocade Virtual ADX to dynamically rewrite URL content in an HTTP request. Also, the HTTP URL Rewrite options allow you to insert, delete, and replace URL content at any offset in an HTTP request.

Seamlessly integrated with Brocade Virtual ADX content switching (CSW), the HTTP URL Rewrite can be configured as a dependent action for primary CSW actions. However, only Forwards and

Persists are typically used for HTTP URL Rewrite actions on HTTP requests, because the other actions do not pass requests to servers.

Before you configure an HTTP URL Rewrite, you should be aware of the following benefits and restrictions for this feature:

• You can configure HTTP URL Rewrite and CSW on HTTP, SSL, or any unknown port.

• HTTP URL Rewrite supports HTTP 1.1 Keepalive and TCP Offload.

• HTTP URL Rewrite is an extension of CSW.

• You define HTTP URL Rewrite actions under a CSW policy.

• Before you define an HTTP URL Rewrite action, you must define a primary CSW action.

• For each matched CSW rule, you can only define one primary action.

• An HTTP URL Rewrite action works only with a primary action that passes client requests to the servers, such as Forward or Persist actions.

• You can define multiple dependent CSW actions that work together with a primary CSW action.

• Dependent CSW actions include HTTP URL Rewrite, log, client-ip insertion, header insertion, cookie insertion, and deletion.

• HTTP URL Rewrite supports nested CSW rules.

• To enable HTTP URL Rewrite under a VIP, you must enable CSW.

• HTTP URL Rewrite cannot be configured as a default action.


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CSW topology

Figure 30 shows a simple CSW network topology.

FIGURE 30 CSW network topology


5

For the CSW configuration shown in

Figure 30

, the following rules apply:

• The Brocade Virtual ADX receives incoming traffic on HTTP port, VIP 10.1.1.100.

• The Brocade Virtual ADX is configured with content switching (CSW) rules and policies. Policy 1 is defined to rewrite URL content and forward the request to the Web server 1.

• If a CSW rule is matched, the Brocade Virtual ADX rewrites the HTTP request and forwards it to

Web Server 1 with server ID 1025 and IP address 10.1.1.1.

• If no CSW rule is matched, the Brocade Virtual ADX takes the default action, sending the HTTP request to Web Server 2 with server ID 1026 and IP address 10.1.1.2.

Request delete configuration

The following sections describe a full configuration process for an HTTP URL Rewrite, and a configuration process for HTTP URL Rewrite actions.

Request delete configuration example

This section describes how to perform a complete configuration HTTP URL Rewrite, using the content delete option. This scenario uses all of the required steps to configure HTTP URL Rewrite, and identifies the steps that are optional.

The configuration process contains the following segments:

•

“Creating a policy with HTTP URL Rewrite” on page 268

•

“Configuring real and virtual servers” on page 269

•

“Enabling content switching” on page 270

•

“HTTP URL Rewrite configuration summary” on page 270


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Creating a policy with HTTP URL Rewrite

To define a CSW rule and create a CSW policy with HTTP URL Rewrite options, follow these steps.

1. Define a CSW rule to match a URL pattern in an HTTP header.

Virtual ADX(config)#csw-rule r11 url pattern /xyz

Syntax: csw-rule rule-name url pattern url-content

2. Define a CSW rule to match a prefix string in an HTTP header.

NOTE

Only one rule is required for configuring HTTP URL Rewrite.

Virtual ADX(config)#csw-rule r12a header Accept-Charset prefix ISO-

Syntax: csw-rule rule-name header header-content prefix prefix-content




4. Specify a primary action to forward a request to a server ID when a rule is matched.


Syntax: match rule-name forward server id

5. Specify a dependent action and delete the matched string when a rule is matched.

Virtual ADX(config-csw-mypolicy)#match r11 rewrite request-delete matched-string

Syntax: match rule-name rewrite request-delete matched-string

NOTE

The rewrite request-delete matched-string option is an HTTP URL Rewrite action. For more

detailed command information, refer to “rewrite request-delete” on page 302.

6. Enable logging for this rule.

Virtual ADX(config-csw-mypolicy)#match r11 log

Syntax: match rule-name log

7. Specify a primary action to forward a request to a server ID when a rule is matched.

Virtual ADX(config-csw-mypolicy)#match r12a forward 1025

Syntax: match rule-name forward server id

8. Specify a dependent action and delete at an offset when a rule is matched.

Virtual ADX(config-csw-mypolicy)#match r12a rewrite request-delete offset 4 2

Syntax: match rule-name rewrite request-delete offset offset length

NOTE

The rewrite request-delete offset option is a HTTP URL Rewrite action.


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NOTE


9. Specify default action for client requests that do not match any other rules. Send such requests to the Web server with ID 1026.

Virtual ADX(config-csw-mypolicy)#default forward 1026

Syntax: default forward server-id

Configuring real and virtual servers

To configure the real and virtual servers, follow these steps.

1. Define a real server (1) with an IP address.

Virtual ADX(config)#server real web1 10.1.1.1

Syntax: server real real-server ip-address

2. Define a real HTTP port on the real server.

Virtual ADX(config-rs-web1)#port http

Syntax: port http

3. Define a real server (2) with an IP address.

Virtual ADX(config-rs-web1)#server real web2 10.1.1.2

Syntax: server real real-server ip-address

4. Define a real HTTP port on the real server and exit.

Virtual ADX(config-rs-web2)#port http

Virtual ADX(config-rs-web2)#exit

Syntax: port http

Syntax: exit

5. Define a virtual server with an IP address.

Virtual ADX(config)#server virtual-name-or-ip csw-vip 10.1.1.100

Syntax: server virtual-name-or-ip vip-name ip-address

6. Define a virtual HTTP port on the virtual server.

Virtual ADX(config-vs-csw-vip)#port http

Syntax: port http

7. Bind HTTP ports on real servers web1 and web2 to the virtual port HTTP.

Virtual ADX(config-vs-csw-vip)#bind http web1 http web2 http

Syntax: bind http real-server http vip-name


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Enabling content switching

To enable content switching, follow these steps.

1. Bind the policy to virtual HTTP port on virtual server.

Virtual ADX(config-vs-csw-vip)#port http csw-policy mypolicy

Syntax: port http csw-policy policy-name

2. Enable CSW on the virtual port.

Virtual ADX(config-vs-csw-vip)#port http csw

Syntax: port http csw

HTTP URL Rewrite configuration summary

The following example shows a summary of the configuration steps.

#csw-rule r11 url pattern /xyz

#csw-rule r12a header Accept-Charset prefix ISO-

#csw-policy mypolicy

#match r11 forward 1025

#match r11 rewrite request-delete matched-string

#match r11 log

#match r12a forward 1025

#match r12a rewrite request-delete offset 4 2

#default forward 1026

#server real web1 10.1.1.1

#port http

#server real web2 10.1.1.2

#port http

#server virtual-name-or-ip csw-vip 10.1.1.100

#port http

#port http csw-policy mypolicy

#port http csw

#bind http web1 http web2 http


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Layer 7 content switching on HTTP response

5


The Brocade Virtual ADX can perform content rewrite on the server responses. In other words, the

Brocade Virtual ADX can not only modify requests in the forward direction, but also the responses in reverse direction. The HTTP response is divided into the "header" part and the "body" part. The

Brocade Virtual ADX can selectively rewrite the header, body, or both.

Response header rewrite

The response header rewrite feature is typically required in an SSL-Offload environment when the

real servers send redirect messages to the incoming clients. Figure 31

shows such a scenario when the Real-Server is not aware of the SSL-Offload but sends a redirect using HTTP. The Brocade

Virtual ADX does not change the response and sends it to the client. The Client, as a result, sends another request using HTTP, and as a result, suddenly moves from a secure HTTPS to HTTP.

FIGURE 31 HTTP response header rewrite

A Brocade Virtual ADX can be programmed to modify such responses and replace "http://" with

"https://". This feature can be applied selectively based on the response code and the embedded

URL. For example, the Brocade Virtual ADX can be programmed to replace only response codes

301 and 302, and only for URLs matching "http://www.example6.com".

In general, this feature is used for modifying the redirect URLs in response codes 301 and 302.

However, it is not limited to modifying redirects and in theory can be configured to modify any other part of the HTTP-header in any other response code.

Configuring HTTP header response rewrite

To enable response header-rewrite, follow these steps.

1. Create a CSW rule specifying the request rule or response codes to be acted upon.

2. Create a CSW rule specifying the string to be modified.

3. Create a CSW policy.

4. Bind the CSW policy to the virtual server port.


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Creating a CSW rule specifying the header response codes

In this step, the header response codes are specified, and a response is inspected only if those codes are found. For example, to specify the redirect response code, the following configuration is required.

Virtual ADX(config)#csw-rule r2 response-status-code 200 400

Syntax: [no] csw-rule rule-name response-status-code low_bound high_bound

Creating a CSW rule specifying the string to be modified

In this step, a CSW-Rule is configured that specifies the string to be matched in a given header. For example, to match the string the redirect messages typically have response codes of 301 or 302, and the new URL is specified in the header "Location."

For example, to match the redirect location "http://www.example6.com," the following rule is required.

Virtual ADX(config)#csw-rule r11 response-header "Location" pattern

"http://www.example6.com"

Syntax: [no] csw-rule rule-name response-header header_name pattern pattern_to_be_found

Creating a CSW policy

When the rules have been defined, they need to be added to a CSW policy. The policy type response-rewrite must be used so as to distinguish the response-rewrite policy from the original

CSW policies, like request-rewrite.

The two rules configured in step 1 and step-2 are added to this policy. The first rule ensures that the policy acts only on responses with response codes 301 or 302. The second rule matches the string "http://www.example6.com" and replaces it with "https://www.example6.com." The offset and length defines the portion of the original match that has to be replaced. The example below shows the rewriting of the entire string. Alternatively, only the first four characters can also be modified, in which case the offset would be 0, with length 4, and the new string would be "https."

Virtual ADX(config)#csw-policy "p1" type response-rewrite

Virtual ADX(config-rew-p1)#match "r1" rewrite response-insert header

Virtual ADXconfig-rew-p1)#match "r11" rewrite request-replace string

"https://www.example6.com/" offset 0 length 19

Syntax: [no] csw-policy policy-name type response-rewrite

Binding a CSW policy to the virtual server port

The final step is to apply the CSW policy to the incoming traffic by binding it to a virtual port. This type of policy is usually applied on port HTTP.


Virtual ADX(config-vs-v1)#port http response-rewrite-policy "p22"

Syntax: port port-type response-rewrite-policy policy-name


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Using multiple cookies under virtual server port

5

In this configuration, the Brocade Virtual ADX rewrites the HTTP response. Whenever response code 301 or 302 appears in the header, together with a redirect URL http://www.example6.com

(signified by the Location header), the Brocade Virtual ADX replaces the URL with https://www.example6.com. In other words, "Location: http://www.example6.com" becomes

"Location: https://www.example6.com." csw-rule r1 response-status-code 301 302 csw-rule r11 response-header "Location" pattern "http://www.example6.com" csw-policy "p1" type response-rewrite

match "r1" rewrite response-insert header

match "r11" rewrite request-replace string "https://www.example6.com/" offset 0 length 19 server real rs1 10.1.1.101

port http



Configuring multiple unique cookie insertion with cookie path

This release adds support for multiple cookies. Based on a URL or any content information contained in a HTTP request, this feature allows Brocade Virtual ADX to introduce to the client user agent a unique cookie with different attributes, such as domain, path, and expiration time.

In previous releases, cookie insertion was configured under a VIP. With more customers having multiple sites hosted per VIP, a single cookie to accommodate all the sites is not sufficient. This feature extends the current implementation of cookie insertion on Brocade Virtual ADX, so that multiple cookies for different sites and applications can be inserted.

NOTE

The following commands is configured under a CSW policy.

Configuring cookie insertion when a particular CSW rule is hit

To configure cookie insertion when a particular CSW rule is hit, use the following command.

Syntax: match rule-name rewrite insert-cookie [ cookie-name [ domain [ path [ age ]]]]

If the server l7-dont-use-gateway-mac command is configured along with a CSW rule for cookie insertion, the embedded link in a web page on the real server (which could be an image) will not appear.

The reason is because the fetch request for the image is second request and it has a cookie embedded. This request does not need insert cookie, so it will go through a normal Layer 7 forwarding path. This will need spoofing to be configured in order to forward the packet.

The first request does not have cookie. So it will go through cookie insertion (content rewrite) code path. This one can take care of server l7-dont-use-gateway-mac command and does not need spoofing configured. But for server l7-dont-use- gateway-mac command to work, spoofing is required.


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NOTE

Spoofing can be configured with the port port number spoofing command under the virtual server configuration.

This can also be achieved by configuring l3-default-gateway.

Configuring cookie insertion in default mode (when no CSW rule is hit)

To configure cookie insertion in default mode (when no CSW rule is hit), use the following command.

Syntax: default rewrite insert-cookie [ cookie-name [ domain [ path [ age ]]]]

The cookie-name variable specifies the name of the cookie to be inserted.

The domain variable specifies the attribute domain for the cookie to be inserted. If the domain variable is not configured or it is configured to be "*," the default domain for the cookie inserted in the HTTP response will be the same as the one in the previous request.

The path variable specifies the attribute path for the cookie to be inserted. If the path variable is not configured or it is configured to be "*," then "/" is defined for the cookie path.

The age variable specifies how many minutes the browser takes to expire the cookie to be inserted.

If the age variable is not configured, the cookie will expire when the browser is closed. If the age variable is configured to be 0, the browser will age out the cookie immediately.

NOTE

The cookie-name variable is required, while the path, domain , and age variables are optional.

Specifications

CLI commands on Brocade Virtual ADX have a limitation on the total length of each command,

When a command includes many keywords or values, the attributes of path or domain can be too long.

The following are the internal system limitations for some attributes introduced by this command:

• cookie-name : Maximum length is 80 bytes.

• path : Maximum length is 255 bytes.

• domain : Maximum length is 80 bytes.

• age :Integer between 0 and 0x1FFFFFFF.

Configuration guidelines

Cookie insertion is typically configured together with cookie switching. If a specific cookie with valid value is found and the associated action can be taken, the Brocade Virtual ADX will take action based on the cookie value; otherwise, it follows other matched rules, in which possibly a cookie insertion is triggered.

The following are the steps to configure the cookie insertion with cookie switching:

• Configure CSW rules and policy

• Bind the CSW policy to a VIP

• Enable CSW on the VIP


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Server passive cookie persistence

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Example

The Brocade Virtual ADX does cookie switching based on the cookie value of "ServerID" or "biz" defined in either rule1 or rule2.

If both rule1 and rule2 are not hit but rule3 is hit, it will forward the request to server group 10 and insert a cookie with name "biz", with path being "business".

If no rule is hit, the Brocade Virtual ADX will take the default action. It will forward the request to server group 1 and insert a cookie with name "ServerID", which expires in 60 minutes.

csw-rule rule1 header "Cookie" search "ServerID=" csw-rule rule2 header "Cookie" search "biz=" csw-rule rule3 url prefix "/business" csw-policy policy1

match rule1 persist offset 0 length 0 group-or-server-id

match rule2 persist offset 0 length 0 group-or-server-id

match rule3 forward 10

match rule3 rewrite insert-cookie "biz" "*" "/business"

default forward 1

default rewrite insert-cookie "ServerID" "*" "*" age 60 server virtual-name-or-ip test 10.2.2.222

port default disable

port http

port http csw-policy "policy1"

port http csw

port http keep-alive

bind http rs1 http server real rs1 10.1.1.1

port http


port http server-id 1100

port http group-id 1 1

port 8080

port 8080 server-id 1208

port 8080 group-id 10 10 server virtual-name-or-ip test 10.2.2.2

port default disable

port http

port http csw-policy "policy1"

port http csw

port http keep-alive

bind http rs1 http rs1 8080

NOTE

Make sure that the system time is configured when you configure cookie age.


This feature provides connection persistence for flows where a cookie is dynamically injected by the backend application server. With this feature enabled, the Brocade Virtual ADX monitors the server reply and looks for a cookie with a specified name. The Brocade Virtual ADX then builds a hash value based on the content of the cookie. This hash value is then stored in a sticky session


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Server passive cookie persistence together with the real server that is responsible for the cookie. Client requests are then monitored for the cookie value associated with the server and a hash value is generated. Where this hash value is equal to the value stored in the sticky session with the real server, client requests are sent to that real server.

For example in Figure 32 , a client sends an initial request to the HTTP port at VIP address:

“10.10.10.1”. The real server at IP address “172.16.0.5”, sends a reply to the client containing a cookie named “JSESSIONID” with a value of “0123456789abcdefg012345643352256”. The

Brocade Virtual ADX makes a hash value from “0123456789abcdefg012345643352256” and creates a session table entry. All subsequent requests from the client that contain the

“JSESSIONID” cookie with the value generated by the real server in its reply are assigned to that real server.

FIGURE 32 Server passive cookie example

276

Configuring server passive cookie persistence

The server passive cookie persistence feature is implemented by configuring CSW rules and policies as described in the following:

•

“Creating a CSW rule to match the server response”

•

“Creating a CSW rule to match the client request”


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•

“Creating a CSW rule to match the client request”

•

“Specifying a CSW action to create persistence information”

•

“Specifying a CSW action to perform persistence lookup and retrieve real server information”

Creating a CSW rule to match the server response

To create a CSW rule to match the server response, use the following command.

Virtual ADX(config)#csw-rule r1 response-header “Set-Cookie” pattern “JSESSIONID”

Syntax: [no] csw-rule rule-name response-header header-name pattern search-string


The header-name variable specifies HTTP header field to be matched in an HTTP response from a real server.

The search-string variable specifies the string within the header-name variable that will be matched in the HTTP response from a real server.

Creating a CSW rule to match the client request

To create a CSW rule to match the client request, use the following command.

Virtual ADX(config)#csw-rule r2 header “Cookie” pattern “JSESSIONID”

Syntax: [no] csw-rule rule-name header header-name pattern search-string


The header-name variable specifies the HTTP header field to be matched in an HTTP request from a client.

The search-string variable specifies the string within the header-name variable that will be matched in an HTTP request from a client.

Specifying a CSW action to create persistence information

To specify a CSW action to maintain persistency information, use the following command.


Virtual ADX(config-csw-policy-p1)#match r1 passive-persist offset 0 length 11

Syntax: [no] match rule-name passive-persist offset persistence-string-offset length persistence-string-length

The rule-name variable is the name of a previously configured CSW rule that was defined to match a server response.

The persistence-string-offset variable specifies the number of characters that will be skipped directly after the search-string variable matched in the specified CSW rule. Normally this value is 0

(zero) which places the start point at the character that is right after the string. As an example, you can configure a search string to “JSESSIONID” as specified for “r1, with an offset of “0”. Where the string found is “JSESSIONID=0123456789abcdefg012345643352256", an offset of “0” will mean that the hash string will start with “=”. If the offset is “7” the string will be parsed beginning with the integer “6”.


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Once the offset point is set by the persistence-string-offset, the system will parse the search-string variable matched in the specified CSW rule up-to the number of characters defined by the value of the persistence-string-length variable. The value of the persistence-string-length variable must be greater than 0 (zero). If the value of the length variable extends beyond the length of the search-string variable, the system will look to the end of the string to define the string used for hashing.

For example: if the search string is “JSESSIONID” and the offset is “0”, the string will be parsed beginning with the “=”. If the persistence-string-length variable is set to “7”, the string used will be

“0123456”.

Specifying a CSW action to perform persistence lookup and retrieve real server information

To specify a CSW action to perform persistency information lookup and use stored real server information to forward requests, use the following command.


Virtual ADX(config-csw-policy-p1)#match r2 persist offset 0 length 11 passive-persist

Syntax: [no] match rule-name persist offset persistence-string-offset length persistence-string-length passive-persist

The rule-name variable is the name of a previously configured CSW rule that was defined to match a client request.

The persistence-string-offset variable specifies the number of characters that will be skipped after the start point of the search-string matched in the specified CSW rule. Normally this value is 0

(zero) which places the start point at the beginning of the string. For example: if the search string is

“JSESSIONID” as specified in r1, and the offset is “0”, the string will be parsed beginning with the capital “J” in “JSESSIONID.” If the offset is “7” the string will be parsed beginning with the capital

“N”.

Once the offset point is set by the persistence-string-offset, the system will parse the search-string matched in the specified CSW rule up-to the number of characters defined by the value of the persistence-string-length variable. The value of the persistence-string-length variable must be greater than 0 (zero). If the value of the length variable extends beyond the length of the search-string , the system will look to the end of the string to define the string used for hashing. For example: if the search string is “JSESSIONID” as specified in r1, and the offset is “0”, the string will be parsed beginning with the capital “J” in “JSESSIONID”. If the persistence-string-length is set to

“7”, the string used will be “JSESSIO”.

Example

The following example is similar to the example shown in Figure 32 with the following operation:

1. The Client request the following URL: www.test.com

2. The server responds with a page and performs “Set-Cookie: PSrvrID=1234567”

The page contains several URL such as: href=”test/nextpage.html?PSrvrID=1234567"


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3. The Client clicks on the link: www.test.com/test/nextpage.html?PSrvrID=1234567

If cookies are enabled, the Client sends: “Cookie: PSrvrID=1234567”

If cookies are disabled, NO cookie is sent back.

4. The load balancer analyzes the incoming request as described:

If “cookie” is found in the header (Cookie:), the cookie value is looked up in the session table for the session bound to the same server.

If no cookie is found, the URL can be analyzed. the cookie name is also found after the “?” value is found. It is also looked up in the session table for the session bound to the same server.

Sample configuration

You can use the following configuration for the previous example.

Virtual ADX(config)#csw-rule "response-cookie" response-header "Set-Cookie" pattern "PSrvrID="

Virtual ADX(config)#csw-rule "uri" url pattern "PSrvrID="

Virtual ADX(config)#csw-rule "forward-cookie" header "Cookie" pattern "PSrvrID="

Virtual ADX(config)#csw-policy "passive1"

Virtual ADX(config-csw-policy-passive1)#match "response-cookie" passive-persist offset 0 length 7

Virtual ADX(config-csw-policy-passive1)#match "forward-cookie" persist offset 0 length 7 passive-persist

Virtual ADX(config-csw-policy-passive1)#match "uri" persist offset 0 length 7 passive-persist

You must then bind the csw-policy to a virtual server port.


This section contains the following sub-sections:

•

“Configuring server and server port persistence with CSW nested rules” on page 279

•

“Configuring persist on the nested rule” on page 280

•

“Configuring persist on the real port” on page 280

NOTE

CSW nested rules are not supported in a csw response rewrite policy.

Configuring server and server port persistence with

CSW nested rules

This section describes the support of CSW rewrite/persist on nested rule and persist on real server ports.

Currently, CSW supports rewrite or persist action on simple rules. The rewrite or persist action on nested rules is not supported, because the place of rewrite or persist action can not be decided on nested rule. This new feature adds a new CLI to specify a base rule within nested one that rewrite or persist action can be based on.


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Also, the current CSW supports the persistence on the group or server ID. Support of persistence on the real server port gives you more granular control.

This feature is to be used with persistence on the group or server ID and is useful when the customer has multiple ports configured on the same group or server, and also wants to direct the request to a particular port instead of load balancing among all the ports.

Persist or rewrite actions can be performed when a nested rule matches, and the location of persistence or rewrite string is determined by a master rule within the nested rule.

Configuring persist on the nested rule

To create a csw nested rule, enter a command such as the following.

Virtual ADX(config)#csw-rule r1 url pattern "pweb"

Virtual ADX(config)#csw-rule r2 url pattern "jsession"

Virtual ADX(config)#csw-rule n1 nested-rule "r1&&r2" master-rule r2

Syntax: [no] csw-rule rule-name nested-rule rule-logic-string master-rule rule-name

NOTE

If a master rule is not specified, the default master in the first rule is the nested rule.

NOTE

If a master rule is not present when the nested rule matches, the persist or rewrite action cannot be performed. It will be treated as nested rule not matched.

Configuring persist on the real port

To specify the real port for a persist action, enter a command such as the following.


Virtual ADX(config-csw-p1)#match n1 persist offset 22 length 2 group-or-server-id real-port 10500

Syntax: [no] match rule-name persist offset offset length offset [[ persist-method [real-port port

[port-failover | fail-close]]] [secondary]]

NOTE

The real port and the failover modes can only be specified when the persist-method variable is group-or-server-id.

The three modes when the specified real port is not available are:

• Default: Layer 4 load balancing is performed.

• Port-failover: The Brocade Virtual ADX fails over to the same port number configured on the virtual port. When there is no real port to be failed over, the client connection is closed.

• Fail-close: The Brocade Virtual ADX immediately closes the client connection.


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Usage example

The customer needs the following request:

• Two real servers, 192.168.1.100 and 192.168.1.101.

• Each server has a different application listening on different ports: 10500 and 10520.

• Each server is configured to a different group, 30 and 31.

• The request with “pweb” and “jsession= groupid ”embedded in the URL is directed to the specified group.

The configuration is as follows.

• For configuring the real server, enter the following commands:

Virtual ADX(config)#server real-name-or-ip rs1 192.168.1.100

Virtual ADX(config-rs-rs1)#port 10500 group-id 20 20 30 30



Virtual ADX(config)#server real-name-or-ip rs2 192.168.1.101




• For configuring the CSW rule, enter the following commands:

Virtual ADX(config)#csw-rule r1 url pattern "pweb"

Virtual ADX(config)#csw-rule r2 url pattern "jsession="

Virtual ADX(config)#csw-rule n1 nested-rule "r1&&r2" master-rule r2

• For configuring the CSW policy, enter the following commands:


Virtual ADX(config-csw-p1)#match n1 persist offset 0 length 2 group-or-server-id real-port 10500

• For configuring the virtual server, enter the following commands:


Virtual ADX(config-vs-vip1)#bind http rs1 10500 rs1 10520

Virtual ADX(config-vs-vip1)#bind http rs2 10500 rs2 10520

Virtual ADX(config-vs-vip1)#port http csw-policy p1

The result of the configuration is if the request has the string "pweb" and also string "/jsession=30" embedded in the url, Then the rule n1 will be matched and the Brocade Virtual ADX will choose to connect to the rs1 (group 30) and the port 10500

If the port 10500 on rs1 is not available, the client request fails over to the port 10500 on rs2.


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Displaying CSW information


Displaying header information

To display information about the HTTP headers encountered in a Layer 7 content switching configuration, enter the following command.

Virtual ADX#show csw-hdr-info

Unknown header list

Name :Hdr Tab Ind :Ref Co

------------------------------------------------------------

Cookie: :0 :1

Unknown header count: 1

Known header list

Name :Hdr Tab Ind

------------------------------------------------------------

Connection: :10

Transfer-Encoding: :11

Content-Length: :12

Host: :13

Cookie: :14

Pragma: :15

Cache-Control: :16

Known header count: 7

XML tag list

Name :Tab Ind :Ref Co

-----------------------------------------------------------banner1 :0 :4 banner2 :1 :1 banner3 :2 :1 banner4 :3 :1 banner5 :4 :1 banner6 :5 :1 banner7 :6 :1 banner8 :7 :1 volume :8 :9

XML tag count: 9

Syntax: show csw-hdr-info

Table 26 describes the information displayed by the show csw-hdr-info command.

TABLE 26 Output from the show csw-hdr-info command

Field...

Description

Unknown header list

Name

Hdr Tab Ind

Ref Co

Unknown header count:

The name of each unknown header field encountered.

The offset in the header table.

The reference count of the number of rules using this header.

The number of unknown headers encountered.


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TABLE 26 Output from the show csw-hdr-info command (Continued)

Field...

Description

Known header list

Name

Hdr Tab Ind

Known header count:

XML tag list

Name

Hdr Tab Ind

Ref Co

XML tag count:

The name of each known header field encountered.

The offset in the header table.

The number of unknown headers encountered.

The name of each XML tag encountered.

The offset in the XML tag table.

The reference count of the number of XML rules using this header.

The number of XML tags encountered.

Displaying CSW rule information

To display information about the Layer 7 content switching rules configured on the device, enter the following command.

Virtual ADX#show csw-rule

Rule Count: 24 Rules Allocated: 24 Rules Deleted: 0

Rule type description: met: method ver: version url: url hdr: header nes: nested con:content

Rule Name |Rule Type |Data |Data |Data |Ref C|Prot

--------------------------------------------------------------------------ban1 |xml-tag |banner1 |equals |1 |0 |http ban2 |xml-tag |banner1 |equals |2 |0 |http ban3 |xml-tag |banner1 |equals |3 |0 |http

Syntax: show csw-rule [ rule-name ]

Table 27

describes the information displayed by the show csw-rule command.

TABLE 27 Output from the show csw-rule command

Field Description

Rule Count The number of Layer 7 content switching rules configured on the device.

Rules Allocated The total number of rules allocated.

Rules Deleted

Rule Name

The total number of rules deleted since the Brocade Virtual ADX was started.

The name of each rule.

Rule Type

Data fields

Ref C

Prot

The type of rule: HTTP method, HTTP version, HTTP header, URL, or XML tag.

The specification for the rule; that is, the content that the rule matches.

The number of nested rules and policies using this rule.

The protocol of the packets matched by the rule.


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To display detailed information for a specified rule, enter a command such as the following.

Virtual ADX#show csw-rule volume1 detail

Rule Name :volume1

Rule Type :xml-tag

Header :volume

Operator :equals

Value :Volume I case-insensitive:FALSE

Ref cnt :1

Sub Rule cnt :1

Sub Rules :volume1

Before Minterm Reduction

Min term mask :0x00000002

Min terms :1

After Minterm Reduction

Min term cnt :1

Minterms :volume1

Hdr/Meth Ind :8

Syntax: show csw-rule rule-name detail

The following table describes the information displayed by the show csw-rule detail command.

Table 28 defines the fields shown in the screen display.

TABLE 28 Output from the show csw-rule detail command

Field Description

Rule Name

Rule Type

Header

Operator

Value

Ref cnt

Sub Rule cnt

The name of the rule.

The type of rule: HTTP method, HTTP version, HTTP header, URL, or XML tag.

The HTTP header matched by the rule.

The operator used to match the content: exists, prefix, suffix, pattern, equals, or search

The content matched by the rule.

The number of nested rules and policies using this rule.

If this is a nested rule, the number of rules referring to this one.

Sub Rules If this is a nested rule, a list of the rules that refer to this rule.

Before Minterm Reduction

Number of minterms for the expression.

Min term mask

Min terms List of minterms.

After Minterm Reduction

Min term cnt Number of minterms for the expression.

Hdr/Meth Ind Index into the header in the method table.


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Displaying CSW policy information

To display information about a Layer 7 content switching policy, enter the following command on the BP.

Virtual ADX#show csw-policy server-sw

Policy Name :server-sw

Policy Type:Content Switching

Policy Index:4

Reference Count:0 total received packet:0 created session:0total scanned packet:0 no session drop:0no session frag drop:0 send redirect packet:0case-sensitive:FALSE

Action code description: fwd: forwardrst: reset-clientper: persist rdr: redirecterr: reply-error got: goto rwt: rewrite log: log con: countdrp: droprec: vir-reset

Flag description:

A: insert-cookieB: delete-cookie C: destroy-cookie

D: req-ins-hdrE: req-ins-client-ipF: resp-ins-hdr

G: delete-contentH: insert-content I: modify-content

L: log

Rule Name |Act|Data1 |Data2 |Data3 |Flags |Hit Cnt

-----------------------------------------------------------------------------url1024 |fwd|1024 | |N/A |_______ |2 url1025 |fwd|1025 | |N/A |_______ |3 default |fwd|1 | |N/A |_______ |10

-------------------------------------------------------------------------------

Syntax: show csw-policy server-sw


TABLE 29 Output from the show csw-policy command

Field Description

Policy Name The name of the policy.

Reference Count Number of VIPs using this policy.

Rule Name The rules configured under the policy.

Act

Data fields

Flags

Hit Cnt

The action specified for each rule.

The specification for the rule; that is, the content that the rule matches.

Information about the content-rewrite actions for the rule, if configured.

The number of times a rule matched.


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To display detailed information about a policy, enter a command such as the following.

Virtual ADX#show csw-policy server-sw detail

Policy Name :server-sw

Policy Type:Content Switching

Policy Index:4

Reference Count:1 total received packet:0 created session:0total scanned packet:0 no session drop:0no session frag drop:0 send redirect packet:0case-sensitive:0

Action code description: fwd: forwardrst: reset-clientper: persist rdr: redirecterr: reply-error got: goto rwt: rewrite log: log con: countdrp: droprec: vir-reset

Flag description:

A: insert-cookieB: delete-cookie C: destroy-cookie

D: req-ins-hdrE: req-ins-client-ipF: resp-ins-hdr

G: delete-contentH: insert-content I: modify-content

L: log

Rule Name |Act|Offse|Data1 | Data2|Data3 |Flags |Hit Cnt

--------------------------------------------------------------url1024 |fwd|0 |1024 | |N/A |_______ |0 url1025 |fwd|1 |1025 | |N/A |_______ |0 default |fwd|0 |1 | |N/A |_______ |0

---------------------------------------------------------------

Total Rule Count :1

Simple Rule Count :1

Minterm Count :1

Database Count :1

XML Tag Count :0

Parse Mask :0x00020000

Parse Tags :url

Vip Bindings :10.168.28.150 [80]

Syntax: show csw-policy policy-name detail

In addition to the information shown in Table 29

, the show csw-policy detail command displays the following information.


TABLE 30 Output from the show csw-policy detail command

Field Description

Offse

Total Rule Count

Simple Rule Count

Minterm Count

The offset into the minterm table.

The total number of rules in the policy.

The total number of simple (not nested) rules used in the policy.

The number of minterms.


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TABLE 30 Output from the show csw-policy detail command (Continued)

Field Description

Database Count

XML Tag Count

Parse Mask

Parse Tags

Vip Bindings

The number of search databases.

The number of XML tags used in the policy.

Mask to indicate the parsing information.

The header or XML tags to be parsed.

The list of VIPs and port numbers using this policy.

Displaying the statistics for all HTTP content rewrites

You can use the show l7-rewrite-info command to display the statistics for all HTTP content rewrites. Using this command on the Management Processor (MP) shows the results of all HTTP content rewrites for both the MP and the BPs. Using this command on a BP (the web switching CPU) shows the results for the BP only.

To display the statistics for all HTTP content rewrites, enter a command such as the following.

Virtual ADX#show l7-rewrite-info

HTTP Content Rewrites:

Total Allocated: 9 Total Freed: 5

Used Now: 4 Allocation Failures: 0

Content Rewritings Done in HTTP Requests:

Cookie Deleted: 0 Cookie Deletion Err: 0

Cookie Destroyed: 1 Cookie Destroy Err: 0

Header Insertion: 2 Header Insertion Err: 0

Client IP Insertion: 2 Client IP Insertion Err: 0

Content Rewritings Done in HTTP Responses:

Cookie Inserted: 1 Cookie Insertion Err: 0

Header Insertion: 0 Header Insertion Err: 0

Total Memory Already Consumed: 64 KB.

Syntax: show l7-rewrite-info

Table 31

defines the fields shown in the screen display.

TABLE 31 Layer 7 Rewrite information

Field Description

HTTP Content Rewrites

Total Allocated

Total Freed

Used Now

Allocation Failures

Content Rewritings Done in

HTTP Requests

Shows the memory slots used to perform HTTP content rewrites.

The total number of allocation times of memory slots used to perform content rewrites.

The total number of freed times of memory slots used for content rewrites.

The number of memory slots that are currently used to perform content rewrites.

The number of failures that occurred while allocating memory for content rewrites.

This section displays information related to cookie deletions, header insertions, and client IP insertions.


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TABLE 31 Layer 7 Rewrite information (Continued)

Field Description

Cookie Deleted

Cookie Deletion Err

Cookie Destroyed

Cookie Destroy Err

Header Insertion

Header Insertion Err

Client IP Insertion

Client IP Insertion Err

The total number of cookies deleted in HTTP requests.

The number of errors that occurred when deleting cookies in HTTP requests.

The number of cookies destroyed during HTTP requests.

The number of errors that occurred while destroying cookies in HTTP requests.

The total number of headers inserted in HTTP requests.

The number of errors that occurred when inserting headers in HTTP requests.

The total number of client IP headers inserted in HTTP requests.

The number of errors that occurred when inserting client IP headers in HTTP requests.

This section contains information about cookie and header insertions.

Content Rewritings Done in

HTTP Responses

Cookie Inserted

Cookie Insertion Err

Header Insertion

Header Insertion Err

Total Memory Already

Consumed

The total number of cookies inserted in HTTP responses.

The number of errors that occurred when inserting cookies in HTTP responses.

The total number of headers inserted in HTTP responses.

The number of errors that occurred when inserting headers in HTTP responses.

The total amount of memory allocated for HTTP content rewrites.

Displaying Layer 7 switching statistics

To display Layer 7 switching statistics, enter the following command at any level of the CLI.

Virtual ADX#show server proxy

Slot alloc = 0 Curr free slot = 99999

Slot freed = 0 Slot alloc fail = 0

Pkt stored = 0 Max slot alloc = 0

Pkt freed = 0 Fwd Stored pkt = 0

Session T/O = 0 Sess T/O pkt free = 0

Session del = 0 Sess del pkt free = 0

DB cleanup cnt = 0 DB cleanup pkt free = 0

Serv RST to SYN = 0 Send RST to C = 0

URL not in 1st pkt = 0 Cookie not in 1st pk = 0

URL not complete = 0 Cookie not complete = 0

Sess T/O rev Sess 0 = 0 Sess T/O Sess diff = 0

Dup SYN Sess diff = 0

Curr slot used = 0 Curr pkt stored = 0

Syntax: show server proxy

Table 32 defines the fields in the screen display.

TABLE 32 Layer 7 Switching statistics

Field Description

Slot alloc

Curr free slot

Number of proxies allocated

Number of proxies possible


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TABLE 32 Layer 7 Switching statistics (Continued)

Field Description

Slot freed

Slot alloc fail

Pkt freed

Max slot alloc

Pkt freed

Number of proxies finished

Number of proxy allocation failures

Number of packets stored by proxy

Maximum number of concurrent proxies

Number of packets freed by proxy

Fwd Stored pkt

Session T/O

Sess T/O pkt free

Session del

Number of stored packets sent to server

Number of session timeouts

Number of stored packets freed due to session timeout

Number of sessions freed by proxy

Sess del pkt free

DB cleanup cnt

Number of stored packets deleted when session was freed

Proxy cleanup count

DB cleanup pkt free Number of stored packets freed during proxy cleanup

Serv RST to SYN Number of times the server sent RST to TCP SYN

Send RST to C

URL not in 1st pkt

Number of times the Brocade Virtual ADX sent RST to client

Number of times the URL string was not in the first packet

URL not complete Number of times the URL string was not complete

Cookie not in 1st pk Number of times the Cookie header was not in the first packet

Cookie not complete Number of times the Cookie header was not complete

Sess T/O rev Sess 0 Number of session timeouts with no reverse session

Sess T/O Sess diff

Dup SYN Sess diff

Number of session timeouts, internal proxy error

Number of duplicate SYNs received, internal proxy error

Curr slot used

Curr pkt stored

Number of existing proxies

Current number of packets stored by proxy

Usage guidelines

When you define an offset or negative offset value to insert or delete a string, the value is not allowed to go beyond the URL value defined by the associated CSW rule. If it does exceed the boundary of the URL value, the Brocade Virtual ADX adjusts it to align with the beginning or the end of the URL.

Similarly, the deletion action is not allowed to delete content beyond the URL value defined by its associated CSW rule. If the string to be deleted does exceed the start or end of the boundary of the

URL or header value content, Brocade Virtual ADX limits the string to be deleted to the part within the boundary.

Syntax: match rule-name rewrite request-insert string [offset | neg-offset offset ]

The rule-name variable defines the name of CSW rule.

The string variable defines the string to be inserted.


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Miscellaneous Layer 7 switching configurations

The offset variable defines the distance of bytes from the offset 0. By default, offset 0 is right after the interested string defined by matched CSW rule.

The Keyword offset or neg-offset indicates that the insertion offset starting after or before the offset 0.

Support for large GET requests

The Brocade Virtual ADX can perform Layer 7 Content Switching on large GET requests (up to

20,000 bytes). Earlier releases supported up to 8,000-byte GET requests.


Cleaning up all hash buckets

To clean up all hash buckets when a server port comes alive, enter the following command.

Virtual ADX(config)#server l7-hashing-bucket-reassign

Syntax: [no] server l7-hashing-bucket-reassign

This command also allows new connections to be forwarded to the server port that has just come up.

Layer 7 content buffering options

In an Layer 7 switching configuration, the Brocade Virtual ADX stores client request packets in the

Layer 7 content buffer while it selects a real server to which to forward the request. The Brocade

Virtual ADX buffers the client request up to the end of the HTTP request, or up to a maximum of 20 packets.

The following two Content Buffering Options allow you to optimize the usage of the Brocade Virtual

ADX’s Layer 7 content buffer:

• Modifying the TCP window size so that the client sends fewer packets before waiting for an ACK

• Configuring the Brocade Virtual ADX not to send an ACK to the client after it has received enough information to select a real server

Changing the TCP window size

The TCP window size in a SYN ACK or ACK packet specifies the amount of data that a client can send before it needs to receive an ACK from a server. By reducing the TCP window size for SYN ACK or ACK packets sent by the Brocade Virtual ADX when performing Layer 7 switching, you can decrease the number of packets a client will send before it waits to receive an ACK from the

Brocade Virtual ADX, thus making more efficient use of the Brocade Virtual ADX’s Layer 7 content buffer.

To change the TCP window size to 1460 bytes, enter the following command.

Virtual ADX(config)#server l7-tcp-window-size 1460

Syntax: server l7-tcp-window-size window size


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The default TCP window size is 8000 bytes. Setting the TCP window size to 1460 bytes causes a client to send only one packet before waiting for the Brocade Virtual ADX to send an ACK, assuming a Maximum Segment Size (MSS) of 1460 bytes. This setting applies only to SYN ACK and ACK packets sent from the Brocade Virtual ADX to the client. The Brocade Virtual ADX does not modify the TCP window size for traffic sent from real servers to clients by way of the Brocade Virtual ADX.

Preventing the Brocade Virtual ADX from sending an ACK to the client

You can configure the Brocade Virtual ADX not to send an ACK back to the client after the Brocade

Virtual ADX receives enough data from the client to select a real server. For example, if you enable this feature in a URL switching configuration, and the Brocade Virtual ADX has received the entire

URL in a request, it does not send an ACK to the client after receiving the last packet. Withholding the ACK prevents the client from sending further data to the Brocade Virtual ADX, increasing the efficiency of the Layer 7 content buffer.

To cause the Brocade Virtual ADX not to send an ACK to the client after it has received enough information to select a real server in a Layer 7 switching configuration, enter the following command.

Virtual ADX(config)#server l7-dont-ack-last-packet

Syntax: server l7-dont-ack-last-packet

HTTP 1.1 support

The Brocade Virtual ADX has HTTP 1.1 support for Layer 7 switching and the Server Connection

Offload (HTTP Connection Proxy) features. These features help reduce TCP connection overhead by offloading the management of TCP connections from application servers and allowing them to dedicate resources for handling application transactions. These features significantly increase the performance and capacity of back-end servers, minimize the number of round trips between users and servers, reduce the bandwidth cost, and improve the Web experience of users.

HTTP was originally designed for simple text documents with embedded images that contain hyperlinks to other documents. For each hyperlinked image, HTTP 1.0, by default, creates a separate TCP connection, even if the images are all on the same server. In comparison, HTTP version 1.1 allows a TCP connection or keepalive connection to remain open until all consecutive requests and responses are complete. This technique is called persistent connection .

Persistent connection is enabled by default on HTTP 1.1 but is disabled by default in HTTP 1.0. For

HTTP 1.0, Web browsers must explicitly insert the HTTP header "Connection: keepalive" to enable persistent or keepalive connections.

This release introduces two modes to support persistent connections: TCP offload mode and keepalive mode. Both modes try to maintain and reuse keepalive connections on both the client side and the server side.

TCP offload mode allows a request from one connection on the client side to re-use any established connection on the server side. TCP offload mode offloads the management of TCP connections from servers so they can dedicate resources to serving HTTP requests instead of managing connections.

The re-use of open connections causes the source IP address and port of the request to be translated from the original connection on the client side to a connection on the server side.

Consequently, a server cannot distinguish between clients simply by the source IP address of the connections. If servers need to distinguish between clients’ source IP addresses, the keepalive mode is recommended. It reuses the connections on the server side for application requests from


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Miscellaneous Layer 7 switching configurations clients that originally created the connections. When a client makes a request for content that is served by a different server, the Brocade Virtual ADX closes the connection to the original server on the server side before setting up a connection with the new server; however, the connection on the client side can still be reused if keepalive mode is enabled on the client connections.

Default settings

By default, Brocade Virtual ADX comes enabled with HTTP 1.0 for any Layer 7 switching feature.

However, HTTP 1.0 connections are non-persistent, and therefore persistent connections or keepalive connections are disabled by default. To support persistent connections, enable TCP connection offload mode or keepalive mode on a virtual port. These modes are enabled at the virtual server level.

Enabling the TCP offload mode

TCP offload mode allows a request from one connection on the client side to reuse any established connection on the server side.

To enable persistent connection in TCP offload mode for the HTTP port on a virtual server named

"vserv1", enter the commands such as the following.

Virtual ADX(config)#server virtual-name-or-ip vserv1

Virtual ADX(config-vs-vserv1)#port http tcp-offload

Syntax: [no] port port tcp-offload [age minutes ] or

Syntax: [no] port port tcp-offload [transactions trans-num ]

The age minutes variable specifies how many minutes a connection on the server side can be kept alive. If it is not specified, by default, the keepalive time will be the same as the session age, which can be defined globally by entering the server tcp-age minutes command or locally under the virtual server level by entering the port port-num tcp-age minutes command.

The transactions trans-num variable specifies the maximum number of HTTP transactions that can be completed on a connection on the server side.

If the age or transaction limit is reached, the connection on the server side is closed and a reset packet will be sent to the server.

Graceful handling of HTTP pipelined requests

If HTTP is enabled, a client supporting persistent connection can use pipelining by allowing multiple requests to be sent over the same connection without waiting for a response for each request. By default, the Brocade Virtual ADX is able to handle HTTP pipelined requests. When it handles the first of the pipelined requests, it holds the rest of pipelined requests. After the client receives the response of the first request, the Brocade Virtual ADX handles the next pipelined request.

The Brocade Virtual ADX can be configured to handle the first request of a pipelined request correctly and optionally send reset to the subsequent requests. This feature helps prevent performance degradation. Reset can be enabled in keepalive mode or TCP offload mode.


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This feature works only when Content Switching is enabled on a virtual server port. if pipelined

HTTP requests are sent in one connection, the Virtual ADX makes the switching decision based on the first request and forwards only the first request to the real server. When the real server sends a complete response to the first request, the Virtual ADX will forward the response to the client. After the client acknowledges the complete response, the Virtual ADX closes the connection by sending a RST to the client.

NOTE

Resetting the HTTP connection can be done in either the keepalive mode or the TCP offload mode.

To reset a pipelined HTTP request in the keepalive mode, first make sure Content Switching is enabled on a virtual server port that will be used for the pipeline reset request.

Then, enter commands such as the following.

Virtual ADX(config)#server virtual-name-or-ip VS1 10.10.10.10

Virtual ADX(config-vs-VS1)#port http

Virtual ADX(config-vs-VS1)#port http keep-alive reset-pipeline-request

Syntax: [no] port [ portid ] keep-alive [reset-pipeline-request]

To reset pipelined HTTP request in the TCP offload mode, enter commands such as the following.

Virtual ADX(config)#server virtual-name-or-ip VS1 10.10.10.10

Virtual ADX(config-vs-VS1)#port http

Virtual ADX(config-vs-VS1)#port http tcp-offload reset-pipeline-request

Syntax: [no] port port tcp-offload [age minutes ] [reset-pipeline-request] or

Syntax: [no] port port tcp-offload [reset-pipeline-request]

Clearing all keepalive connections

To delete all keepalive server side connections on all the applicable virtual servers, enter the following command on the Brocade Virtual ADX.

Virtual ADX#clear server keep-alive virtual

Syntax: [no] clear server keep-alive [virtual | real] [ server-name ] [ port ]

Enter virtual if you want to delete all the keepalive connections associated with the virtual server, or real if they are to be deleted from the specified real server.

The optional server-name and port variables specify the name or port of the virtual or real server from where you want to delete the keepalive server-side connections. When you enter this command, all the keepalive connections will be removed from the reuse pool. The Brocade Virtual

ADX sends reset packets to the real or virtual servers to close any open connections.


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Displaying transactions and connections

To display information about the transactions and connections for Layer 7 switching over keepalive connections, enter the following command.

Virtual ADX4/1#show server session keep-alive


Hash size = 200001




Real Server St CltConn:Cur/Tot SerConn:Cur/Tot CurrTrans IdleSerCon TotTrans

MyServer01 1 11/46 3/5 2 1 147

MyServer02 1 0/0 0/0 0 0 0

MyServer03 1 0/0 0/0 0 0 0

Table 33 specifies the show server session keep-alive command fields and its description

TABLE 33 Fields in the show server session keep-alive display

Field Description

CltConn:Cur/Tot: Number of current and total client-side connections on this BP.

SerConn:Cur/Tot: Number of current and total server-side connections on this BP. When persistent connection is enabled, the number of current and total server-side connections is typically much less than the current and total client-side connections, because a server-side connection can be reused by requests from any client-side connection.

CurrTrans: Number of busy server side connections that are in the process of serving HTTP transactions.

The difference between number of current client-side connections and CurrTrans indicates the number of current idle client-side connections.

IdleSerCon:

TotTrans

Number of idle server-side connections that are available to be re-used by new requests made to the same server. The sum of CurrTrans and IdleSerCon is equal to the number of current server-side connections.

TotTrans: Total number of HTTP transactions that have been successfully completed for the server. Because a persistent connection allows multiple HTTP transactions to be done,

TotTrans typically have a much higher value than the total number of both client-side and server-side connections.

In the example above, MyServer01 has 11 concurrent client-side connections and 3 concurrent server-side connections to the Real Server MyServer01. Two of the 3 server-side connections are processing different HTTP transactions and the third one is idle.

In addition, clients made a total of 46 connections to the Brocade Virtual ADX; while the Brocade

Virtual ADX only needs to create a total of 5 server-side reusable keep-alive connections to

MyServer01 to serve all the requests sent on the 46 client-side connections. In those 46 client-side connections and 5 server-side connections, 147 HTTP transactions have been completed.

Syntax: show server session keep-alive

NOTE

This command only works on the Brocade Virtual ADX.


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Layer 7 CSW pseudo stack client-side retransmission handling

The Brocade Virtual ADX Content Switching (CSW) pseudo stack needs to store HTTP request packets from the client before it is able to perform server selection. If the stored packets are not acknowledged by the CSW pseudo stack and these packets get dropped before reaching the server, they can be retransmitted by the client. However, there are cases when the Brocade Virtual

ADX needs to acknowledge those stored packets before forwarding them to the server. An example of this is when the client’s HTTP request spans multiple packets, and the client expect an acknowledgment before transmitting the remaining request packets. Upon receiving all request packets, the Brocade Virtual ADX performs server selection and transmits all requests packets to the server. Since the current CSW pseudo stack does not keep the stored packets once they are sent out, they will never be transmitted if these packets get dropped. If this occurs, the client will keep retransmitting the request for acknowledgement to the Brocade Virtual ADX, until the TCP timeout expires. As a result, the client will notice that the HTTP transaction never gets completed.

The Brocade Virtual ADX supports handling of HTTP request retransmission with Layer 7 pseudo stack. When the Layer 7 CSW pseudo stack retransmission handling is enabled, the Brocade

Virtual ADX acknowledges and stores the client TCP packets, and does not clear its buffer until the request packets are acknowledged by the server. If the retransmission timer triggers before the request packets are acknowledged, the Brocade Virtual ADX will resend the stored packets.

The same situation can happen at the server side traffic. If server response headers span multiple packets, the Brocade Virtual ADX also needs to send the acknowledgment to the server. With this feature enabled, the server-side retransmission is also supported. The Layer 7 CSW pseudo stack retransmission handling feature is disabled by default.

Enabling the Layer 7 CSW client-side retransmission handling

To enable Layer 7 CSW pseudo stack retransmission handling feature, enter the command as follows:

Virtual ADX(config)#server csw enable-retransmission

Syntax: [no] server csw enable-retransmission


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Displaying the Layer 7 CSW client-side retransmission handling information

In order to display information about Layer 7 CSW client-side retransmission handled by the

Brocade Virtual ADX, use the show server proxy keep-alive command. A truncated display is shown:



...

Client-side statistics:

In seq. packets = 412 Unexpected data = 0

Out of seq. packets:

Syn_recv = 0 Wait_req state = 0

Not_complete = 0 Req_sent state = 0

Reply_sent = 0 = 0

Retransmit packets:

Syn_sent = 0 Req_sent state = 0

Reply_sent = 0 Req_sent state(old) = 0

Reset cast to ack = 0 Fin cast to ack = 0

Ack cast to Reset = 0 Dup rev in Syn_sent = 0

Dup rev in src nat = 0 = 0

Reset packets received:

Syn_recv = 6 Wait_req = 0

Syn_sent = 0 Req_sent = 0

Rep_sent = 0 Page_replied = 0

Unknown = 0 Others = 0

...

Hash Bucket Change:

Current serv is down = 0 Serv exceed max-conn = 0

Lower BP wins = 0 = 0

...


This command displays the HTTP keep-alive connection statistics and also includes the retransmission counters.

NOTE

The Layer 7 CSW pseudo stack retransmission handling feature does not support High Availability

(HA).


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Layer 7 CSW pseudo stack server-side TCP packet out-of-sequence handling

With the current Layer 7 Content Switching (CSW) pseudo stack, the Brocade Virtual ADX expects all TCP packets from the server-side to arrive in-sequence. If the server-side TCP packets are received out-of-sequence, the Brocade Virtual ADX will silently drop the out-of-sequence TCP packets and then wait for either the TCP stack timeout to expire, or for the server to retransmit. If this occurs, the end-user will experience slowness while browsing certain Web pages over the

Internet.

The Brocade Virtual ADX Layer 7 CSW pseudo stack supports handling of packet-drops and out-of-sequence TCP packets arriving from server-side as well.

Displaying server-side link connections

In order to display information about the server-side out-of-sequence TCP packets handled by the

Brocade Virtual ADX, use the show server proxy keep-alive command. The statistics relevant to the out-of-sequence TCP packets are shown (in bold) in the following abbreviated output and described

in Table 34

.



Server-side statistics:

...

TCB status:

Total in mem = 512000 Current in pool = 0

Allocated from mem = 301 Freed to mem = 300

Allocated from pool = 0 Freed to pool = 0

...

Connection unreusable reasons:

Small window = 0 No rev sess = 0

Not reusable = 0 Fin/RST received = 0

Image = 0 = 0

Delayed ACK list status:

Total TCBs in list = 12 Curr TCBs in list = 0

Generated ack num = 0

Out of sequence packet buffering:

total stored oos pkt = 3 total freed oos pkt = 3

total timeout drop = 0 total oversize drop = 0

...

SYN_RECV = 0 WAIT_REQ = 0

NOT_COMPLETE = 0 REQ_STORED = 0

SYN_SENT = 0 REQ_SENT = 0

PAGE_REPLIED = 0 STATE_UNKNOWN = 0

...

KA DEBUG: URL_MULTI_STATE_FREED [ 31] = 113

...


NOTE

This command is available at the Brocade Virtual ADX BP console only.


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Setting up SSL session ID switching

The fields described in Table 34

provide statistics about out-of-sequence (oos) TCP packets.

TABLE 34 Out-of-sequence TCP packets statistics

Field Description

Total stored oos pkt

Total freed oos pkt

The total number of out-of-sequence packets buffered by the Brocade Virtual ADX.

The total number of out-of-sequence packets transmitted by the Brocade Virtual ADX.

The number variable specifies the number of database entries. This variable can range from 8,192 to 256,000.


SSL (Secure Sockets Layer) is a protocol for secure World Wide Web connections. The SSL protocol protects your confidential information with server authentication, data encryption, and message integrity. SSL is layered beneath application protocols such as HTTP, Telnet, FTP, Gopher, and NNTP, and layered above the TCP/IP connection protocol. This structure allows SSL to operate independently of the Internet application protocols. With SSL implemented on both the client and server, your Internet communications are transmitted in encrypted form, ensuring privacy.

For SSL to work, all the SSL connections between a client and server must reach the same host.

SSL connections come in sequentially on particular ports; only one is open at a time. However, each must go to the same server.

SSL Session ID switching is the Brocade Virtual ADX’s ability to connect a client to the same real server to which it had previously established an SSL (Secure Sockets Layer) connection.

SSL provides security in Web transactions. An SSL connection is initiated when a user clicks a hyperlink that begins with "https" (for example, https://secure.brocadenet.com). The browser

(client) initiates an SSL connection with the server on TCP port 443, a secure link is negotiated, and encrypted data is transferred across it.

The SSL Handshake Protocol (SSLHP), one of two component protocols of SSL, negotiates the connection between the client and server. SSLHP establishes security parameters for an SSL session, including the SSL version number and the method of data encryption to use. One of the security parameters set by SSLHP is the SSL Session ID, a variable-length value contained in the session_id field in SSLHP messages. The SSL Session ID indicates whether the client wants to use the security parameters established in a previous session or establish a completely new connection.

To set up SSL session ID switching, perform the following tasks:

1. Configure the real servers for SSL.

2. Configure the virtual server for SSL session ID switching.

3. Adjust the age timer in the Brocade Virtual ADX’s database (optional).

4. Adjust the maximum number of session ID to real server associations that the Brocade Virtual

ADX can store in its internal database (optional).


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SSL session ID workflow

Figure 33 illustrates how the initial SSLHP messages exchanged between a client and server,

client_hello and server_hello, establish an SSL Session ID.

FIGURE 33 How the SSL Handshake Protocol Establishes a Session ID

5

If the value in the session_id field that the client sends to the server is non-zero, the Brocade

Virtual ADX can connect the client to the server that originally sent the Session ID value.

Figure 34

illustrates how this function, called SSL Session ID switching, works.

NOTE

SSL Session ID switching is supported for SSL v3.0 and higher only. In SSL versions prior to 3.0, the session ID was established later in the handshaking process, after the client and server had started exchanging encrypted data. If the session ID is encrypted, the Brocade Virtual ADX cannot make forwarding decisions based on this information.

If the client source IP address is changed, session persistence based on SSL Session ID does not work since Session ID information is not copied across Application Processors. If the source IP is changed, the session may be processed by different Application Processor. The only exception is

SI-1008-1 model with single Application Processor.


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FIGURE 34 How the Brocade Virtual ADX uses an SSL Session ID to Select a Real Server

1

Client sends initial client_hello message with empty session_id

Client

Internet

4

Remote Access

Router

When client wants to resume session, it sends a client_hello message containing the session_id it received from the server

5

3

Brocade Virtual ADX stores session_id value in an internal database that maps session_id values to real servers

Brocade Virtual ADX looks up session_id value in its internal database, sees that this session_id value maps to real server rs10

6

2

Real server rs10 responds with server_hello message containing non-zero session_id

Brocade Virtual ADX passes client_hello message to real server rs10

Real Server rs10

209.157.22.10

Real Server rs20

209.157.22.20

Figure 34

illustrates the following process.

1. The first time a client attempts to establish an SSL connection to the server, there is no history of a previous SSL session, so the session_id field in the client_hello message it sends to the server is empty.

2. The server (in this example, real server rs10) sees that the session_id field in the client_hello message is empty, indicating the client wants to establish a new SSL session. The server responds to the client with a server_hello message that contains a session_id field with a non-zero value.

3. The Brocade Virtual ADX examines the value in the session_id field sent by the server. The

Brocade Virtual ADX adds this value to an internal database, associating it with the real server that sent it. This association between the session_id value and the real server resides in the

Brocade Virtual ADX’s database for a user-specified amount of time (default 30 minutes), after which it is aged out. In this example, the Brocade Virtual ADX would map the value in the session_id field to real server rs10.

4. When the client resumes the SSL connection to the server, it sends a client_hello message containing the session_id value sent by the server.

5. The Brocade Virtual ADX examines the value in the session_id field sent by the client and looks it up in its internal database.

6. If the value in the session_id field maps to a real server, the Brocade Virtual ADX initiates a TCP connection to the server and passes the client_hello message to it. The Brocade Virtual ADX forwards subsequent packets between the client and server with modifications to the IP and

TCP header for sequence number, acknowledgment number, and checksum adjustment.


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Configuration Example

Configuring the real servers for SSL

To configure the real servers for SSL shown in

Figure 34

, enter commands such as the following.







Syntax: server real-name real-server-name ip-addr

Syntax: port ssl

The server real-name command defines the names and IP addresses of the real servers.

The port ssl command adds port 443 (SSL) to the real servers.

Configuring the virtual server for SSL session ID switching

The following commands enable SSL Session ID switching on a virtual server called sslVIP.

Virtual ADX(config)#server virtual-name-or-ip sslVIP 10.157.22.241

Virtual ADX(config-vs-sslVIP)#port ssl session-id-switching

Virtual ADX(config-vs-sslVIP)#bind ssl rs10 ssl

Virtual ADX(config-vs-sslVIP)#bind ssl rs20 ssl

Syntax: port ssl session-id-switching

Syntax: port port-number session-id-switching

Syntax: bind ssl real-server-name ssl

The port ssl session-id-switching command enables SSL Session ID switching on this virtual server.

The bind ssl ssl command binds the virtual server to SSL services on the real servers. In this example, the commands associate real servers rs10 and rs20 with the virtual server.

NOTE

For clarity, the bindings in the example are shown as two separate entries. Alternatively, you can enter all the binding information as one command: for example, bind ssl rs10 ssl rs20 ssl.

Adjusting the age timer

By default, the Brocade Virtual ADX keeps the entry associating a session_id with a real server in its database for 30 minutes. After 30 minutes, the entry ages out of the database. You can change the length of time the Brocade Virtual ADX keeps the entry in the database,

To change the aging period from its default of 30 minutes to 10 minutes, enter a command such as the following.

Virtual ADX(config)#server session-id-age 10

Syntax: [no] server session-id-age minutes

The minutes variable is defined in minutes within the range from 2 through 60.


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Command reference

Adjusting the maximum number of session_id-to-real-server associations

By default, the Brocade Virtual ADX can store in its database 8,192 entries associating a session_id with a real server.

You can change the maximum number of database entries to any larger value up to 256,000 by entering a command such as the following.

Virtual ADX(config)#server max-ssl-session-id 256000

Syntax: server max-ssl-session-id number

The number variable specifies the number of database entries. This variable can range from 8,192 through 256,000.

Command reference

This section describes the following HTTP URL Rewrite options. These "options" are part of the match command.

•

“rewrite request-delete”

•

“rewrite request-insert”

•

“rewrite request-replace”

rewrite request-delete

Use the rewrite request-delete option in the CSW policy configuration mode to delete content, as shown in the following.

Virtual ADX(config-csw-mypolicy)#match r11 rewrite request-delete offset 4 2

Syntax: match rule-name rewrite request-delete {matched-string | neg-offset offset length | offset offset length | string ASCII string }

The matched-string parameter specifies the matched-string option for the request to delete a string defined by a rule.

The neg-offset parameter specifies the negative-offset option for the delete request as defined by the following variables:

• The offset variable is the value of the deletion offset.

• The length variable is the value of the length of content to be deleted.

The offset parameter specifies the positive-offset option for the delete request as defined by the following variables:

• The offset variable is the value of the deletion offset.

• The length variable is the value of the length of content to be deleted.

The string parameter specifies the string option for the delete request as specified by the following variable:

The ASCII-string variable, which specifies the value of the string to be deleted.


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rewrite request-insert

Use the rewrite request-insert option in the CSW policy configuration mode to insert content, as shown in the following.

Virtual ADX(config-csw-mypolicy)#match r11 rewrite request-insert abc offset 4

Syntax: match rule-name r ewrite request-insert {[ ASCII-string [neg-offset decimal | offset decimal ]] | client-ip | header}

The ASCII-string variable specifies the value of the string for the offset options, listed below, in the insert request.

The neg-offset parameter specifies the negative offset option for the insert request as the value specified in the decimal variable.

The offset parameter specifies the positive offset option for the insert request as the value specified in the decimal variable.

The client-ip parameter specifies the client IP option for the insert request.

NOTE

The value of the client-ip must be defined under the VIP command.

The header parameter specifies the header option for the insert request.

NOTE

The value of the header must be defined under the VIP command.

rewrite request-replace

Use this option in the CSW policy configuration mode to replace content, as shown in the following.

Virtual ADX(config-csw-mypolicy)#match r11 rewrite request-replace matched-string

Syntax: match rule-name rewrite request-replace {matched-string ASCII string | string

ASCIIstring-old ASCIIstring-new }

The matched-string parameter specifies the matched-string option for the request to replace a string defined by a rule that is specified by the ASCII string variable.

The string parameter specifies that a string defined by the ASCIIstring-old variable must be replaced by a string of the ASCIIstring-new variable.


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Command reference


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Chapters the

6

Overview

This chapter describes the Hot Standby high availability (HA) feature for the Brocade Virtual ADX. In

Hot Standby HA, two Brocade Virtual ADX devices must be in a network that you configure to serve as a redundant pair (primary and secondary). One Brocade Virtual ADX is always active while the other Brocade Virtual ADX is always standby (idle).

If the active Brocade Virtual ADX fails, the idle standby Brocade Virtual ADX assumes the active duties and becomes the new active device. The active and standby Brocade Virtual ADX devices remain in their states until one of the following events forces a change in their status:

• An increase or decrease in the count of the router ports plus the server ports on each Brocade

Virtual ADX. The Brocade Virtual ADX with the highest number of active ports is declared the active device.

• Failure of any BP or MP forcing the Brocade Virtual ADX to reload.

• A reload.

For more information on the failover behavior of Hot-standby HA, refer to the

“Hot Standby HA protocol operations” section.

NOTE

The Hot Standby HA feature is supported for IPV4 and IPv6.


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Overview

Hot Standby HA protocol operations

Figure 35 illustrates a typical Hot Standby HA configuration.

FIGURE 35 Typical Hot Standby HA

306

When Brocade Virtual ADX-A initializes in a Hot Standby HA configuration, it is in the standby state.

When it sends Hello messages and no other Brocade Virtual ADX responds to these messages,

Brocade Virtual ADX-A sets itself to the active state. When Brocade Virtual ADX-B initializes, it also goes through Hello-message processing. When Brocade Virtual ADX-B sends Hello messages,

Brocade Virtual ADX-A responds with an Active status. When Brocade Virtual ADX-B receives this status, it assumes the Standby status. Then Brocade Virtual ADX-A in the active state performs the following four stages of synchronization:

• Port map synchronization

• MAC table synchronization

• Server information synchronization

• Session synchronization


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Hot Standby HA configuration modes

6

When the entire synchronization process is completed, Brocade Virtual ADX-B calculates Brocade

Virtual ADX-A router-port plus server-port count.

• If the Brocade Virtual ADX-A count is greater than or equal to Brocade Virtual ADX-B, Brocade

Virtual ADX-A remains in the active state and Brocade Virtual ADX-B remains in the standby state.

• If Brocade Virtual ADX-A has a lower count of the router port plus the server port, Brocade

Virtual ADX-B forces Brocade Virtual ADX-A to the standby state, and Brocade Virtual ADX-B sets itself to the active state.

To avoid a loop, the standby Brocade Virtual ADX becomes a dumb device. It is completely isolated and does not process any SLB traffic. However, while the standby Brocade Virtual ADX is idle, it performs the following functions:

• Continuously listens to the active Brocade Virtual ADX for failover preparation and receives session-sync messages from the active Brocade Virtual ADX. The moment a session is created on the active Brocade Virtual ADX, the active Brocade Virtual ADX synchronizes its session table on the BPs to match the BPs on the standby Brocade Virtual ADX. Synchronization of a session involves session creation, session deletion, and age updates. No CLI commands are required to invoke session synchronization from the active Brocade Virtual ADX to the standby


• Performs health checks. The active and standby Brocade Virtual ADX devices perform Layer 2,

Layer 3, Layer 4, and Layer 7 health checks independently.

• Processes Hello messages.

If the active Brocade Virtual ADX fails, the standby Brocade Virtual ADX becomes active and immediately takes over the processing of the SLB traffic. Because the sessions were already synchronized from the previously-active Brocade Virtual ADX, failover is transparent to users.

Hot Standby HA configuration modes

Hot-Standby HA can be configured in two different modes as follows:

• Non-Promiscuous mode with default non-shared MAC option

• Promiscuous mode with shared MAC option

Non-Promiscuous mode with default non-shared MAC option

By default, the virtual switch is set to non-promiscuous mode. To perform seamless failover in this mode, the new active Brocade Virtual ADX sends gratuitous ARPs with its interface MAC addresses to the adjacent switches or hosts, immediately after a fail over.

In this case, if gratuitous ARPs can be honored by the next hop router or directly connected hosts, enable the non-promiscuous mode (if not enabled by default) on the receiving data ports.

In the Brocade Virtual ADX CLI, you need not configure optional keyword shared-mac in the server backup ethernet port vlan-id vlan MAC command.


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Hot Standby HA Configuration Considerations

Promiscuous mode with shared MAC option

When a server does not honor gratuitous ARP, the virtual switch in the ESX hypervisor needs to be set to promiscuous mode.

This mode is known to the Brocade Virtual ADX based on an optional keyword configured in the server backup ethernet port vlan-id vlan MAC [ shared-mac ] command, where MAC is normally one of the HA sync port MAC out of the two Brocade Virtual ADXs. The new optional keyword shared-mac indicates if promiscuous mode is “ON”.

Hot Standby HA Configuration Considerations

When configuring Hot Standby HA, consider the following:

• If only one device is present and the Hot Standby HA feature is enabled, the Brocade Virtual

ADX will function in "single-box" mode until the second Brocade Virtual ADX becomes available.

• There are two versions of Hot Standby HA:

• Standard Hot Standby HA - The Brocade Virtual ADX management IP, VIPs, and real servers are all in the same subnet.

• Source-IP/src-standby-ip Hot Standby HA - The Brocade Virtual ADX management IP and

VIPs are in one subnet. Real servers are in a different subnet. Additional commands are required for this version.

Configuring standard Hot Standby HA

FIGURE 36

Figure 36 shows the minimum required configuration for Standard Hot Standby HA.

Minimum required configuration for Standard Hot Standby HA

308

Perform the following steps to enable this configuration.

1. On Brocade Virtual ADX A, place the untagged Hot Standby HA port (sync-link) in its own port-specific VLAN:

Virtual ADX-A(config)#vlan 999 by port

Virtual ADX-A(config-vlan-999)# untagged ethe 3

Placing the Hot Standby HA port in its own VLAN prevents unnecessary traffic from going over the backup (sync) link.


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NOTE

You must use a dedicated port for the HA sync link.

2. Configure the server backup port, shared MAC address between the Brocade Virtual ADX devices, and any connected router ports:

Virtual ADX-A(config)#server backup ethe 3 000c.290d.e85f vlan-id 999

Virtual ADX-A(config)#server router-ports ethernet 1

Syntax: server backup ethernet portnum mac-addr vlan-id [shared-mac]

The server backup ethernet command must be configured exactly the same on both Brocade

Virtual ADX devices. It has four parameters.

The portnum variable specifies the port where the syn-link is connected. This port connects this Brocade Virtual ADX to its counterpart. In the example, 3 is the port number.

The mac-addr variable specifies the sync-link interface MAC address of one of the Brocade

Virtual ADX devices. Refer to the show interfaces brief command. This address must be the same on both Brocade Virtual ADX devices.

The vlan-id variable specifies a VLAN that you want to use. In this example, the sync-link Hot

Standby HA port is in VLAN 999.

The shared-mac option must be set if the virtual switch is in promiscuous mode. For more

information on non-promiscuous and promiscuous modes, refer to the “Hot Standby HA configuration modes” on page 307.

The server router-ports command enables the Brocade Virtual ADX to count the number of upstream (or downstream) router ports connected to the ADX. Both Brocade Virtual ADX devices must use the same router-ports numbers, such as 1 in this example. The reason is the standby Brocade Virtual ADX is a dummy device that learns nothing, such as MACs, on its own.

3. Save the configuration.

Virtual ADX-A #write memory

.Write startup-config in progress.

.Write startup-config done.

Virtual ADX-A#reload

NOTE

Be sure to reload the software after configuring or changing the server backup command. If you change the port number of the backup while the Brocade Virtual ADX is load balancing, clients will not be able to ping the VIP.

4. Configure the second Brocade Virtual ADX (Brocade Virtual ADX-B). On this system, port 3 is the Hot Standby HA port. Using the same port numbers and MAC address is a requirement.

Notice the MAC address on each Brocade Virtual ADX matches.

Virtual ADX-B(config)#server backup ethe 3 000c.290d.e85f vlan-id 999

Virtual ADX-B(config)#server router-ports ethernet 1

Virtual ADX-B(config)#vlan 999 by port

Virtual ADX-B(config-vlan-999)#untagged ethe 3


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Virtual ADX-B#write memory

.Write startup-config in progress.

.Write startup-config done.

Virtual ADX-B#reload

5. Use show server backup and show log to obtain the Brocade Virtual ADX status in the Hot

Standby HA configuration.

The following screen shots display the different stages of reload and show how a Brocade Virtual

ADX comes up in a Hot Standby HA configuration.

Virtual ADX-A#show server backup

Server Backup port = 3 <----------- Sync-link port on this Brocade Virtual ADX

Backup group id = 0

Switch state = Standby

SLB state = 1 <-------------------- Start of the SLB sync.

Five stages: 0>1>2>3>4>0

Share MAC = Off <------------------ Indicates whether promiscuous mode is configured.

Peer sync state = 0

SLB Partner MAC valid= 0 <------------- 0 indicates the MAC below is not valid

SLB Partner MAC = 0000.0000.0000 <----- Peer Brocade Virtual ADX MAC

SLB Partner HA sync port MAC = 0000.0000.0000

SLB Partner VLAN ID = 999 <--------- VLAN used to perform heartbeat between Brocade Virtual ADX

SLB Partner port cnt = 0

SLB Backup preference = 0 minutes

SLB Backup timer = 1000 milliseconds

Active attempts = 0

Transitions, activates =

Pdus sent =

0, standby

0, Pdus recv

Null Pdus sent

No pdus

Routers ports

Server ports

=

=

=

=

My Cost = 9, Peer Cost = 10

0, Mac pdu sent

0, no port maps

0, Partner Routers ports

0, Partner Server ports=

=

=

=

=

=

0

0

0

0

0

0

Brocade Virtual ADX A is running in single-box mode, because Brocade Virtual ADX B is not yet discovered.

Virtual ADX-A#show server backup

Server Backup port = 3

Backup group id = 0

Switch state = Active <------------ Assumes Active since no peer was detected by sending null PDUs

SLB state = 0<-------------------- State returns to 0

Share MAC = Off

Peer sync state = 0

SLB Partner MAC valid= 0

SLB Partner MAC = 0000.0000.0000<-- Still did not find peer and entry remains all zeros

SLB Partner HA sync port MAC = 0000.0000.0000

SLB Partner VLAN ID = 999




Active attempts = 0


Pdus sent =

0, standby

0, Pdus recv

Null Pdus sent

No pdus

Routers ports

Server ports

=

=

=

=


215, Mac pdu sent

0, no port maps


1, Partner Server ports

=

=

=

=

=

=

0

0

0

0

0

0


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Now Brocade Virtual ADX B comes up with Brocade Virtual ADX A already up and running.

Virtual ADX-B#show server backup

Server Backup port = 3

Backup group id = 0

Switch state = Standby

SLB state = 0<------------------------- Goes from 0>1>2>3>4>0

Share MAC = Off

Peer sync state = 0

SLB Partner MAC valid= 0

SLB Partner MAC = 000c.290d.e85f <----- Peer MAC appears when SLB state returns to 0

SLB Partner HA sync port MAC = 000c.290d.e88c

SLB Partner VLAN ID = 999




Active attempts = 0


Pdus sent =

0, standby

0, Pdus recv

Null Pdus sent

No pdus

Routers ports

Server ports

=

=

=

=


244, Mac pdu sent

0, no port maps


1, Partner Server ports

=

=

=

=

=

=

0

133<-- From

0

0

0

0

Virtual ADX-A

Table 35 describes the information displayed by the show server backup command.

TABLE 35 Field descriptions for show server backup command

Field Description

Switch state

SLB state

Indicates whether this Brocade Virtual ADX is the active or the standby Brocade Virtual

ADX. The state can be one of the following:

•

Active

•

Standby

When a Brocade Virtual ADX comes up in the Hot Standby HA configuration, it requests the following information from the peer Brocade Virtual ADX:

•

Port map information

•

MAC information

•

Server mapping information

•

Session information (Fail-over session sync)

After this processing is completed, the Brocade Virtual ADX goes to the "SLB synchronization complete" state.

This field displays one of the following states during the request for peer information:

•

SLB_SYNC_COMPLETE state (Value = 0). All synchronization requests from the local

Brocade Virtual ADX have been sent to the peer Brocade Virtual ADX. This process is now complete (value = 0).

•

SLB_SYNC_REQ_MAP state (Value = 1). Denotes the local Brocade Virtual ADX is requesting the peer Brocade Virtual ADX for port map information.

•

SLB_SYNC_REQ_MAC state (Value = 2). Denotes the local Brocade Virtual ADX is requesting the peer Brocade Virtual ADX for MAC information.

•

SLB_SYNC_REQ_SERVERS state (Value = 3). Denotes the local Brocade Virtual ADX is requesting the peer Brocade Virtual ADX for Server mapping.

•

SLB_SYNC_REQ_L4 state (Value = 4). Denotes the local Brocade Virtual ADX is requesting the peer Brocade Virtual ADX for session synchronization (fail-over session sync).


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Additional configuration variations

TABLE 35 Field descriptions for show server backup command (Continued)

Field Description

Share MAC

SLB Partner MAC valid

SLB Partner MAC

Indicates whether the shared-mac option through the server backup command is set. The state is one of the following:

•

Off indicates that the virtual switch is set to non-promiscuous mode.

•

On indicates that the virtual switch is set to promiscuous mode.

Indicates whether the SLB partner MAC address listed in the SLB Partner MAC field is valid. The value can be one of the following:

•

0 – invalid

•

1 – valid

The MAC address on the other Brocade Virtual ADX, indicating Layer 2 connectivity between the Brocade Virtual ADX devices. If this field contains all zeros, double-check the connection between the Brocade Virtual ADXs and verify that both Brocade Virtual ADX devices are powered on.

Displays the MAC address of the partner HA interface.

SLB Partner HA sync port MAC

SLB Partner port cnt The number of ports on the other Brocade Virtual ADX.

Transitions, activates The number of times this Brocade Virtual ADX has changed from standby to active.

Transitions, standby The number of times this Brocade Virtual ADX has changed from active to standby.

Pdus sent The number of Layer 4 synchronization packets this Brocade Virtual ADX has sent to the other Brocade Virtual ADX.

Mac pdu sent

No pdus no port maps

The number of MAC-layer synchronization packets this Brocade Virtual ADX has sent to the other Brocade Virtual ADX.

The number of missed Layer 4 or MAC-layer PDUs.

The number of missed port map PDUs. Port map PDUs are used by the Brocade Virtual

ADX to discover information about the maps on the other Brocade Virtual ADX.


This section provides the following configuration variations:

•

“VIP and servers in different subnets”

•

“Source-NAT in Hot Standby”

VIP and servers in different subnets

If VIP and servers are in different subnets, configure a standby IP address under the interface or virtual Ethernet interface that is configured in the same subnet as the servers. The same standby-ip must be configured on both the Brocade Virtual ADX. On the servers, use this standby-ip as the default gateway.

Syntax: [no] standby-ip ip-add { ip-mask | prefix length } default-gateway


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Figure 37 shows a configuration with the VIP and servers in different subnets.

FIGURE 37 VIP and servers in different subnets


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Configuring additional HA parameters

Source-NAT in Hot Standby

Figure 38 shows a configuration for seamless failover in Hot Standby when Source-NAT is enabled.

FIGURE 38 Seamless failover in Hot Standby HA when Source-NAT is enabled


This section provides additional configuration parameters for Hot Standby HA:

•

“Configuring a backup group ID”

•

“Setting the backup timer”

•

“Enabling backup preference”

•

“Configuring failover based on active VIP count”

•

“Configuring failover based on the number of active virtual ports”

•

“Delayed failover”

•

“Configuring a Brocade Virtual ADX to remain in standby state”


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Configuring a backup group ID

Hot Standby HA redundancy enables a Brocade Virtual ADX to serve as an automatic backup for another Brocade Virtual ADX. Each Hot Standby HA pair consists of two Brocade Virtual ADX devices. You can configure up to 127 Hot Standby HA pairs within a single L2 broadcast domain. To enable this support, configure a backup group ID on each of the Brocade Virtual ADX devices. Both

Brocade Virtual ADX devices in a given pair have the same ID. The ID uniquely identifies the pair.

When you configure a backup group ID, both Brocade Virtual ADX devices in a Hot Standby HA pair use the ID when exchanging backup information. If a Brocade Virtual ADX receives a backup information packet, but the packet’s backup group ID does not match the Brocade Virtual ADX’s backup group ID, the Brocade Virtual ADX discards the packet.

If the broadcast domain contains multiple Hot Standby HA pairs, you must configure backup group

IDs on all pairs. If the broadcast domain contains only one Hot Standby HA pair, you do not need to configure a backup group ID.

To configure a backup group ID, enter the following command.

Virtual ADX(config)#server backup-group 1

Syntax: [no] server backup-group id

The id variable specifies the backup group ID. Enter a number from 1 to 7. The default value is 0.

Enter the same ID on both Brocade Virtual ADX devices in a Hot Standby HA pair. Do not enter the same ID on a Brocade Virtual ADX that is not one of the Brocade Virtual ADX devices in the Hot

Standby HA pair. This feature is turned on by default.

Use the show server backup command in a Hot Standby HA topology to display the backup ID information. If there is a group-ID mismatch, both Brocade Virtual ADX devices become active

(instead of one standby and one active).

Setting the backup timer

The standby Brocade Virtual ADX assumes the active role if the it does not receive a Hello message or Layer 4 session synchronization data from the active Brocade Virtual ADX within a certain number of seconds since having received the last Hello message or synchronization data.

By default, the standby Brocade Virtual ADX waits one second since having received the last Hello message or data to receive a new message or data. If the standby Brocade Virtual ADX does not receive a new Hello message or data within one second, the standby Brocade Virtual ADX assumes that the active Brocade Virtual ADX is no longer available and takes over the active role.

In some configurations, particularly those in which the active Brocade Virtual ADX is performing a lot of processing, it is possible for frequent failovers to occur. In this situation, although the active

Brocade Virtual ADX is still available and actively serving load balancing or other requests, the active Brocade Virtual ADX does not always send the Hello message or synchronization data in time for the standby Brocade Virtual ADX. As a result, the standby Brocade Virtual ADX takes over the active role. If similar conditions cause the newly active Brocade Virtual ADX to sometimes miss sending the Hello messages or synchronization data in time, failover occurs again.

You can prevent unnecessary state flapping between the two Brocade Virtual ADXs by increasing the backup timer. When you increase the backup timer, the standby Brocade Virtual ADX waits longer to receive new Hello messages or synchronization data from the active Brocade Virtual ADX.

As a result, flapping is reduced or eliminated.


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NOTE

The backup timer must have the same value on both Brocade Virtual ADX devices in the HA pair.

To set the backup timer on a Brocade Virtual ADX in an HA pair, enter the following command.

Virtual ADX(config)#server backup-timer 50

This command sets the backup timer to 5 seconds (50 * 100 milliseconds).

Syntax: [no] server backup-timer time

The time variable specifies how long the Brocade Virtual ADX, when it is the backup Brocade Virtual

ADX, will wait for a Hello message or synchronization data from the active Brocade Virtual ADX before assuming the active Brocade Virtual ADX is no longer available. You can specify a value from

5 (one half second) through 100 (10 seconds), in units of 100 milliseconds each. The default is 10

(one second).

Enabling backup preference

You can configure one of the Brocade Virtual ADX devices in the HA pair to always be the active

Brocade Virtual ADX. When you enable server backup-preference on one of the Brocade Virtual ADX devices, that Brocade Virtual ADX is always active by default. The only event that can cause the other Brocade Virtual ADX to be active is unavailability of the default active Brocade Virtual ADX or its link to the backup Brocade Virtual ADX. To allow graceful insertion, the Brocade Virtual ADX does not immediately assume the active role, but instead waits for a configurable number of minutes before taking the active role.

To enable server backup preference, enter the following command.

Virtual ADX(config)#server backup-preference 5

Syntax: [no] server backup-preference wait-time

The wait-time variable specifies how long the Brocade Virtual ADX waits before assuming the active role. The Brocade Virtual ADX does not immediately become the active Brocade Virtual ADX but instead waits the number of minutes you specify. You can specify from 5 through 30 minutes. This variable does not have a default.

Configuring failover based on active VIP count

By default, the HA peer failover is based on router ports and server ports. You can configure the HA peer to fail over based on router ports and active VIP counts instead of just the router ports. When this type of failover is configured, the following occurs:

• If neither of the two nodes in the peer has any router ports, the one having more active-VIPs will be the active node; no status change if the active-VIPs also tie.

• If one node has no router ports, but another has at least one router port, the latter will be the active node.

• If both nodes have at least one router port, the one having more active-VIPs will be the active node. If active-VIPs tie, the node with more router ports will be the active node. There is no status change if both active-VIPS and router ports tie.


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Virtual ADX(config)#server backup-vip-cnt

Syntax: [no] server backup-vip-count

Configuring failover based on the number of active virtual ports

You can configure the HA peer to fail over based on router ports and active virtual ports, instead of just the router ports (default) or the combination of router ports and virtual servers as described in

“Configuring failover based on active VIP count”

. When a failover is configured to be based on the number of active virtual ports, the following occurs:

• If neither of the two nodes in the peer has any router ports, the one having more active

VIP/VPORT counts will be the active node; no status change if the number active VIP/VPORT counts ties.

• If one node has no router ports, but another has at least one router port, the latter will be the active node.

• If both nodes have at least one router port, the one having more active VIP/VPORT counts will be the active node. If the number of active VIP/VPORT counts tie, the node with more router ports will be the active node. There is no status change if the number of both active virtual ports and router ports tie.


Virtual ADX(config)#server backup-vport-cnt

Syntax: [no] server backup-vport-cnt

This feature can be configured with or without the server backup-vip-cnt command as described:

• If the server backup-vip-cnt command is not configured, only the number of active virtual ports is compared. The node with more active virtual ports will be considered to have more

VIP/VPORT counts, and a tie is called if they have an equal number of active virtual ports.

• If both the server backup-vip-cnt and server backup-vport-cnt commands are configured, the number of active virtual ports will have a higher precedence than the number of active virtual servers. Consequently, the node with a larger number of virtual ports will always be considered as having a higher VIP/VPORT count and in the case of a tie on the active virtual port count, the node with a larger number of active virtual servers will be considered as having a higher

VIP/VPORT count. A tie condition occurs where both nodes have an equal number of both virtual servers and virtual ports.

NOTE

The server backup-vport-cnt command must be configured on both Brocade Virtual ADX devices in the pair. To avoid an unnecessary failover during configuration, we suggest that you enable this feature on the active ADX device first. Also, the feature should be disabled on the standby ADX device first.


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Delayed failover

With this feature configured, when a Brocade Virtual ADX device detects a failover condition because of a VIP/VPORT count change, the failover will be delayed. At the end of the period of delay, the Brocade Virtual ADX device examines the conditions that led to the failover condition and performs a failover if the conditions still apply. If they no longer apply, the failover will be cancelled.


Virtual ADX(config)#server backup-delay-seconds 20

Syntax: [no] server backup-delay-seconds backup-wait-seconds

The backup-wait-seconds variable specifies the number of seconds that the Brocade Virtual ADX will wait before performing a failover. Values can be specified from 0 through 1200 seconds.

Specifying 0 disables this feature and causes failover to occur immediately without any delay.

This feature applies only when configuring the server backup-vip-cnt or server backup-vport-cnt commands.

NOTE

The server backup-delay-seconds backup-wait-seconds command must be configured on both

Brocade Virtual ADX devices in the active/standby pair.

Configuring a Brocade Virtual ADX to remain in standby state

This feature ensures that a Brocade Virtual ADX always remains in the standby state, regardless of any changes in the system parameters (such as no heart beat, fewer router ports, and other changes). Use this feature when there is undesirable flapping between active and standby states, which can occur when the CPU utilization on the standby Management Processor is very high and causes the standby Brocade Virtual ADX to drop the heart beat messages sent by the active


To force a Brocade Virtual ADX to remain in the standby state, enter the remain-standby command.

Virtual ADX(config)#server backup-remain-standby

Syntax: server backup-remain-standby

NOTE

Use the remain-standby command with caution because both Brocade Virtual ADX devices can become standbys; thereby creating traffic loss.

If the Brocade Virtual ADX is active when this command is configured, the Brocade Virtual ADX transitions to the standby state and remains as the standby until the command is removed. The transition is logged as "Forced to turn standby.”

After you enter the remain-standby command, every attempt by the Brocade Virtual ADX to go into the active state is recorded and suppressed. This information is available under the "Active attempts" field in the show server debug command.


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Configuring the forwarding of synchronizing messages

6

Configuring the forwarding of synchronizing messages

In a Hot Standby HA configuration, the active Brocade Virtual ADX and the backup Brocade Virtual

ADX continuously communicate through synchronizing messages. These messages contain Layer 4

–Layer 7 session status information and are only used by the Brocade Virtual ADX devices.

Some of the messages can travel over a non-dedicated private link between the two Brocade

Virtual ADX devices. Another Brocade Virtual ADX can be in the middle of this link, acting as a Layer

2 or Layer 3 Switch passing traffic between the active and backup Brocade Virtual ADX devices.

In this situation, messages sent between the active and backup Brocade Virtual ADX devices can be intercepted and dropped by the Brocade Virtual ADX in the middle, and not forwarded to the active or backup Brocade Virtual ADX devices. This could cause loss of synch between the active and backup Brocade Virtual ADX devices. To prevent this from happening, use the server fwd-l4-sync command to configure the Brocade Virtual ADX in the middle to simply forward the synching messages and not intercept them.

To configure the Brocade Virtual ADX in the middle to forward the synchronizing messages, enter the following command on the Brocade Virtual ADX connecting the active and the backup Brocade

Virtual ADX devices.

Virtual ADX(config)#server fwd-l4-sync

Syntax: server fwd-l4-sync

Configuring synchronization with HA

You can use the config-sync command line utility to synchronize an SLB configuration from the active Brocade Virtual ADX to the standby Brocade Virtual ADX. For information about the config-sync command, refer to the "Initiating the Synchronization" section of the "Brocade Virtual

ADX System Management" chapter in the Brocade Virtual ADX Administration Guide .

Hot-standby HA with routing protocols

When the upstream and the downstream routers are on the different VLANs, the routing protocols like OSPF and BGP should be up and running on both active and standby devices in addition to static routes. Brocade Virtual ADX learns the routes advertised by the routing protocol as well as the static routes configured. As soon as a device becomes active, the new active starts allowing the packets for forwarding. In contrast, though the same learnt and configured routes are present on the standby device, it does not forward the packets.

With the routing protocols configured, both active and standby devices advertise the routes to the upstream and downstream routers, including the VIP RHI routes. However Brocade Virtual ADX automatically adjusts the cost of the advertised routes without any additional configuration, ensuring that the traffic is always targeted to the active device. This cost alteration by the system is not be reflected in the running configuration of the Brocade Virtual ADX.


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NOTE

Manual alteration of the cost or the metric of the routing protocols can affect the traffic forwarding by the HA pair. For internal BGP (IBGP), you need to enable the compare-med-empty-aspath flag on the upstream and downstream router for cost and MED to be considered for route selection. The

BGP RFC defines all vendor support.

FIGURE 39 HA using routing protocol- Sample network topology


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Tie state of virtual link and HA physical link using health checks

The Brocade Virtual ADX virtual interface is unaware of the state of the physical interface and this result is an inconsistent port state. In HA scenarios, failover cannot be triggered even if the associated physical interface is down. Hence, the virtual interface state is tied with that of the physical interface. The existing ICMP Boolean health checks are deployed in these scenarios as follows:

Virtual ADX(config)#healthck c1 icmp

Virtual ADX(config-hc-c1)#dest-ip 3.3.3.1

Virtual ADX(config)#healthck c2 icmp

Virtual ADX(config-hc-c2)#dest-ip 3.3.3.2

Virtual ADX(config)#healthck c3 boolean

Virtual ADX(config-hc-c3)#or c1 c2

The healthck command is introduced in server router-port command to tie the health checks as follows:

Virtual ADX(config)#server router-port e 1 healthck c3

NOTE

In a Hot-Standby HA configuration, the server port interface is connected to the external device using the virtual switch. If the port on the external device is down, the Brocade Virtual ADX does not detect it because of the presence of the virtual switch in between. The result is that the status of the server-port is not be marked as down. To overcome this drawback, you can configure the server backup-vip-cnt or server backup-vport-cnt command while running Hot-Standby HA to perform failover based on a real-server health check failure.

For more information on configuring OSPF, refer to the Brocade Virtual ADX Switch and Route

Guide .


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SIP Server Load Balancing

Chapter

7

SIP overview

The Session Initiation Protocol (SIP) is a signaling protocol used by numerous IP communication products to create session-oriented connections between two or more endpoints in an IP network.

SIP is emerging as the preferred technology for Voice over IP (VoIP) implementations.

Application-aware network switches play a vital role in increasing the uptime and availability of

IP-based services such as VoIP. Many customers rely on this technology to meet mission-critical application requirements. Together with advanced SIP intelligence, Virtual ADX switches offer a highly scalable, available, and secure load balancing infrastructure for SIP applications.

SIP is an application-layer protocol that can establish, modify, and terminate multimedia sessions, such as Internet telephony. In this implementation, Virtual ADX SIP server load balancing balances

SIP requests and responses, based on a Call-ID.

SIP Server Load Balancing is based on a request-and-response transaction model that is similar to

HTTP. Each transaction consists of a request that invokes a particular method on the server, and at least one response. The method is carried within the request message.

For more information, see SIP: Session Initiation Protocol - RFC 3261.


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SIP overview

SIP packet flow

Figure 40 demonstrates the basic operation of SIP; location of an endpoint, signal of a desire to

communicate, negotiation of session parameters to establish the session, and tear-down of the session after completion.

FIGURE 40 SIP packet flow

324

The example in Figure 40 shows packet exchange between two SIP clients, also known as User

Agent Clients (UACs). In the figure each message is labeled with the letter "F" and a number for reference. The session established between the two end-clients is facilitated by the SIP proxy server. User1 "calls" User2 using a SIP identity, a type of Uniform Resource Identifier (URI) called a

SIP URI . The SIP URI is similar to an e-mail address, typically containing a username and a host name. In this case, it is sip:user1@brocade.com

, where brocade.com is the domain of User1's SIP service provider.


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SIP overview

7

SIP is based on an HTTP-like request-and-response transaction model. Each transaction consists of a request that invokes a particular method, or function, on the server, and at least one response. In this example, the transaction begins with User1's SIP phone sending an INVITE request addressed to User2's SIP URI. The INVITE request contains a number of header fields. The fields present in an

INVITE request include a unique identifier for the call (Call-ID), the destination address, User1's address, and information about the type of session that User1 wishes to establish with User2. The

INVITE (message F1 in Figure 40 ) would look like the following example:

INVITE sip:user2@brocade.com SIP/2.0

Via: SIP/2.0/UDP pcuser1.brocade.com;branch=dkDKdkDKdkDK1111

Max-Forwards: 50

To: User2 <sip:user2@brocade.com>

From: User1 <sip:user1@brocade.com>;tag=1122334455

Call-ID: 12341234123412@pcuser1.brocade.com

CSeq: 123456 INVITE

Contact: <sip:user1@pcuser1.brocade.com>

Content-Type: application/sdp

Content-Length: 142

Because User1's SIP phone does not know the location of User2's SIP phone, it sends the INVITE message to the SIP proxy server that is serving the brocade.com domain. The address of the brocade.com proxy server is known to the SIP phone through static configuration or through

Dynamic Host Configuration Protocol (DHCP). The proxy server receives the INVITE request and sends a 100 (Trying) response back to User1's SIP phone. This response contains the same To,

From, Call-ID, CSeq, and branch parameter in the Via field as the INVITE, which allows User1's SIP phone to correlate this response to the previously sent INVITE. The proxy server consults a database, generally called a location service , that contains the current IP address of User2. It then forwards (or proxies) the INVITE request there. Before forwarding the request, the proxy server adds an additional Via header field value with its own address (the INVITE already contains User1's address in the first Via field).

User2's SIP phone receives the INVITE and alerts User2 of the incoming call from User1; that is,

User2's phone rings. User2's SIP phone indicates this by a 180 (Ringing) response, which is routed back through the SIP proxy server in the reverse direction. When User1's SIP phone receives the

180 (Ringing) response, it passes this information to User1, using an audio ringback tone.

If User2 decides to answer the call (User2 picks up the handset), the SIP phone sends a 200 OK response to indicate that the call has been answered. The 200 OK contains the Via, To, From,

Call-ID, and CSeq header fields that are copied from the INVITE request, and a message body with the Session Description Protocol (SDP) media description of the type of session that User2 is willing

to establish with User1. The 200 OK (message F6 in Figure 40 ) would look like the following

example.

SIP/2.0 200 OK

Via: SIP/2.0/UDP pcproxy.brocade.com

;branch= dkDKdkDKdkDK2222;received=10.1.1.2

Via: SIP/2.0/UDP pcuser1.brocade.com

;branch= dkDKdkDKdkDK1111;received=10.1.1.1

To: User2 <sip:user2@brocade.com>;tag=dkdkdk1

From: User1 <sip:user1@brocade.com>;tag=1122334455

Call-ID: 12341234123412@pcuser1.brocade.com

CSeq: 123456 INVITE

Contact: <sip:user2@10.1.1.3>

Content-Type: application/sdp

Content-Length: 131


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SIP overview

The 200 OK message is routed back through the SIP proxy server to the User1's SIP phone, which then stops the ringback tone and indicates that the call has been answered. Finally, User1's SIP phone sends an acknowledgement (ACK) message to User2's SIP phone to confirm the reception of the final response (200 OK). This ACK is sent directly from User1's SIP phone to User2's SIP phone, bypassing the SIP proxy server. This occurs because the endpoints have now learned each other's

IP addresses from the Contact header fields through the INVITE/200 OK exchange, which was not known when the initial INVITE was sent. This completes the INVITE/200/ACK three-way handshake used to establish SIP sessions.

The media exchange between User1 and User2 now begins using the format that they have agreed upon through SDP. In general, the end-to-end media packets take a different path from the SIP signaling messages. At the end of the call, User2 disconnects (hangs up) the phone and generates a BYE message. This BYE is routed directly to User1's SIP phone, again bypassing the SIP proxy.

User1 confirms the session termination with a 200 OK response.

SIP client registration

Registration is another common SIP operation. Registration is the means through which the SIP domain's registrar server learns the current location of SIP clients (UACs). Upon initialization, and at periodic intervals, the SIP clients send REGISTER messages to the domain's SIP registrar server.

The REGISTER messages associate an individual SIP URI (sip:user@brocade.com) with the IP address of the machine which the user is currently logged on. The registrar server writes this association to a database, called the location service , where it can be used by the SIP proxy server of the domain. Often, a registrar server and the location service for a domain are co-located with the proxy server for that domain.

SIP terminology

This section describes terms and concepts that you might find useful when configuring SIP SLB.

• Request-URI: Every SIP user has a URI. One SIP user calls another by setting the SIP URI of the latter in the request message, also called the request-URI , which appears before all message headers.

• UAC: A User Agent Client (UAC) is a logical entity that creates a new request. The role of UAC lasts only for the duration of the transaction.

• UAS: A User Agent Server (UAS) is a logical entity that generates a response to a SIP request.

The response accepts, rejects, or redirects the request.

• Proxy server: A proxy server is an intermediary entity that acts as both a server and a client for the purpose of making requests on behalf of other clients. A proxy server is primarily a router, which means its job is to ensure that a request is sent to another entity nearer to the targeted user. A proxy interprets and, if necessary, rewrites specific parts of a request message before forwarding it.

• Redirect server: A redirect server is a UAS that generates 3xx responses to requests it receives, directing the client to contact an alternate set of URIs.

• Registrar server: A registrar server accepts REGISTER requests and places the information it receives in those requests into the location service for the domain it handles.


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SIP message headers

This section describes SIP message headers that you might find useful when making decisions about SIP server load balancing.

Call-ID

The Call-ID is a header field that appears in all SIP requests and responses. This header field acts as a unique identifier to group together all messages belonging to the same call. It must be the same for all requests and responses sent by either the UAC or UAS in a dialog.

Call-ID is generated by the combination of a random string and the host name or IP address of a particular UAC. There is no length restriction on Call-ID. In the first implementation, a real server is selected based on the hash value of Call ID (stateless mode) or the value of Call ID (stateful mode).

• Record-Route: The Record-Route header field is inserted by a proxy in a request to force future requests in the dialog to be routed through the proxy; for example, Record-Route: <sip: server10.example1.com; 1r>

• From: The From header field indicates the logical identity of the initiator of the request. It contains a URI and, optionally, a display name. This field must contain a "tag" parameter, chosen by the UAC.

IP addresses of the host on which the UAC is running should not be used as FROM URIs, as these are not logical names.

• To: The To header field specifies the desired logical recipient of the request. This might not be the ultimate recipient of the request. Normally, the initial To field is set to be the value of the

Request-URI. One exception is the REGISTER method.

• Via: The Via header field indicates the path taken by the request so far and indicates the path that should be followed in routing responses. A Via header field value contains the transport protocol used to send the message, the client's host name or network address, and possibly the port number at which it wishes to receive responses. It is a mandatory field for the UAC or

UAS SIP proxies, and guarantees that the responses traverse through the same route as the requests.

The branch ID parameter in the Via header field value serves as a transaction identifier, and is used by proxies to detect loops.

• Max-Forwards: The Max-Forwards header field must be used with any SIP method to limit the number of proxies or gateways that can forward the request to the next downstream server.

The Max-Forwards value is an integer from 1 through 255 indicating the remaining number of times that a request message is allowed to be forwarded. The recommended initial value is 70.


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FIGURE 41

Figure 41 shows an overview of a Virtual ADX SIP server load balancing implementation.

Virtual ADX SIP Server Load Balancing implementation

328

There are three kinds of SIP servers:

• Proxy server

• Redirect server

• Registrar server

In

Figure 41

, the Virtual ADX SIP SLB uses the Domain-1 VIP to load balance SIP requests from

Client A (user1) or Client B (user2) among Domain 1 proxy servers and registrar servers.

The SIP Server Load Balancing uses the Domain-2 VIP to load balance SIP requests from Client A

(user1) or Client B (user2) among Domain 2 proxy servers and registrar servers.

The Virtual ADX offers support for the following SIP servers in accordance with RFC 3261:

• Proxy

• Redirect

• Registrar

The Virtual ADX supports the following methods in accordance with RFC 3261:

• INVITE

• REGISTER

• ACK


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• CANCEL

• BYE

• OPTIONS

Additionally, the following methods are supported:

• SUBSCRIBE

• NOTIFY

• Other proprietary methods

SIP and call persistence specifications

The SIP server load balancing has the following specifications:

• By default, server selection is persistent on Call-ID.

• Pass-through SIP traffic from real SIP servers to SIP clients gets translated. The Virtual ADX replaces the source IP (SIP server real IP) with Virtual IP (VIP).

• The Virtual ADX does not modify any of the SIP header fields.

• The Virtual ADX does not perform SIP-aware NAT.

• This implementation is based on RFC 3261.

NOTE

The Virtual ADX SIP SLB is not implemented as a SIP proxy server, but rather as a load balancer of proxy or registrar traffic.


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Sample deployment topologies

Virtual ADX switches offer application-aware advanced intelligence for SIP server load balancing.

The following sections describe some SIP server load balancing scenarios.

SIP server load balancing with DSR mode

Figure 42 shows an SIP server farm built around Virtual ADX application switches.

FIGURE 42 SIP server farm with DSR mode

330

Figure 42 demonstrates a typical use case in which the Virtual ADX application switch provides

Call-ID based server persistence for UDP SIP traffic. The Call-ID attribute that uniquely identifies a

SIP call is used to maintain session persistence. Due to the unique call flow requirements of SIP, most SIP implementations require you to enable Direct Server Return (DSR) mode on the Virtual

ADX switch.

Because User1's SIP phone does not know the location of User2's SIP phone, it initiates a new SIP session by sending an INVITE request to the SIP proxy server. It also generates a unique identifier

(Call-ID) for the call. Because the SIP proxy server used by User1's SIP phone is actually the virtual

IP address hosted on the Virtual ADX switch, the Virtual ADX switch receives the INVITE request and, using a server selection mechanism, identifies the best available SIP server for this INVITE.

The Virtual ADX uses the Call-ID attribute value to select one of the SIP servers in either stateless or stateful mode. For all SIP transactions within a dialog that use the same Call-ID, the Virtual ADX selects the same SIP server. A new INVITE message with a different Call-ID is again subjected to server load balancing and may be forwarded to a different SIP server.


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The proxy server receives the INVITE request and sends a 100 (Trying) message to User1's SIP phone. Because the Virtual ADX switch is configured in DSR mode, the response message that is sourced from the virtual IP address flows directly to User1's SIP phone, bypassing the Virtual ADX.

The proxy server then consults the location service and forwards the INVITE request directly to

User2's SIP phone, again bypassing the Virtual ADX, and is sourced from the proxy server's own IP address.

NOTE

The proxy server's IP address must be reachable from all SIP clients.

User2's SIP phone receives the INVITE and alerts User2 of an incoming call. User2 replies with a

Ringing message to the proxy server. If User2 answers the call, a 200 OK message is sent to the proxy server. The proxy server forwards this message to User1's SIP phone. Upon receiving the 200

OK message, User1's SIP phone sends an acknowledgement (ACK) message directly to User2's SIP phone, bypassing the proxy server. User1 and User2 SIP phones now begin media exchange and, upon completion, a BYE message closes the call.

Some SIP servers may be configured to use a virtual IP address (VIP) as the source address for all

communications. Figure 43 shows SIP packet flows in this type of configuration.

FIGURE 43 SIP server farm with DSR mode and SIP server using VIP as source address

In this implementation, the SIP proxy server must use the same Call-ID for both legs of communication (the same Call-ID for message exchange with both SIP clients within a given SIP dialog). Session persistence and transaction integrity can only be achieved if the proxy server uses the same Call-ID.


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SIP server load balancing with non-DSR mode

Figure 44 shows a SIP server farm with proxy servers connected inline (non-DSR mode) with the

Virtual ADX switch.

FIGURE 44 SIP Server Load Balancing with non-DSR mode

332

To maintain session persistence and transaction integrity, this implementation has the following requirements:

• The SIP proxy server should use the same Call-ID for both legs of communication (for example, for message exchange with both SIP clients within a given SIP dialog).

• For all outbound SIP communications, the proxy server should use the same UDP source port as that used as the destination port for all inbound communications.

NOTE

If the proxy server uses a source port other than the one used as the destination port for inbound communications, then the packets arriving from the proxy server go untranslated by the Virtual ADX.

The proxy server IP address must be reachable from all SIP clients in such cases.


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SIP server health monitoring

There are two types of SIP servers of particular importance: SIP proxy servers and SIP registrar servers. The Virtual ADX supports advanced UDP Layer-7 application health checks for both server types.

Virtual ADX switches can be enabled to send REGISTER or OPTION messages to SIP servers to track their health. When an error-free response status (default is 200 OK) is received, then the Virtual

ADX marks the SIP server as being available, and starts assigning new SIP sessions to the available servers.

The switches can also be configured to send health-monitoring messages at user-defined frequency and retrial attempts. By default, 200 OK is considered a valid response code. Optionally, you can configure the switch to accept other response codes that indicate a healthy and available server.

SIP messages with specific SIP methods are switched to the appropriate SIP server. As an example,

REGISTER messages are forwarded only to the SIP registrar server; whereas INVITE messages are distributed among SIP proxy servers.

Configuring SIP SLB

SIP server load balancing over UDP is available in stateless SLB mode and stateful SLB mode.

SIP SLB over UDP features the following elements in both stateless and stateful modes:

• Persistence parameter can be extended: The persistence parameter can be extended to other key header fields, such as the VIA header. This applies to both SIP stateful and SIP stateless modes.

• Support for fragmented UDP support: Applies to both SIP stateful and SIP stateless modes.

The following elements are supported in stateful SLB mode only:

• SIP stateful support: Server selection is based on round-robin persistence on a user-configured key header, such as Call-ID, and corresponding SIP sessions are created for this purpose.

• Server initiated SIP requests handling: Sessions are created so that subsequent transactions with the same persistence parameter are directed to the same real server. This applies to SIP stateful mode only. This enables the Virtual ADX to load balance the back-to-back user agent

(B2BUA) SIP servers.

• A SIP session created in Virtual ADX with multiple barrel processors are synchronized to all barrel processors (BPs).

• Redundancy support: SIP stateful supports both hot standby HA and symmetric active-standby

HA configuration by synchronizing SIP sessions to peer box. Symmetric Active-Active HA configuration is not recommended.

SIP SLB over UDP (Stateless SLB mode)

The following sections discuss SIP over UDP.


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Configuring a SIP proxy server and enabling health check

Complete the following steps to configure a real SIP proxy server and its health check.

1. Configure a real server and IP address for a proxy server and enter the real server configuration mode.

Virtual ADX(config)#server real proxy-server-1 10.1.3.1

Syntax: [no] server real name ip address

2. Specify the SIP port.

Virtual ADX(config-rs-proxy-server-1)#port sip

Syntax: [no] port sip

NOTE

You can specify SIP port number 5060 or the keyword sip.

3. Specify a proxy server and a health check method with options.

Virtual ADX(config-rs-redirect-server-1)#port sip sip-proxy-server health-check-method options

Syntax: port sip [sip-proxy-server] [health-check-method [ options | register ] ]

[health-check-no-dsr]

• sip-proxy-server—Identifies the server as a SIP proxy server.

• health-check-method—Specifies the SIP health check method.

• options—Enables health check through OPTION messages.

• register—Enables health check through REGISTER messages (default method).

• health-check-no-dsr—Specifies for health check to be sent to a real server rather than a virtual server.


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Configuring a SIP registrar server and enabling health check

Complete the following steps to configure a real SIP registrar server and its health check.

1. Configure a real server and IP address for a registrar server and enter the real server configuration mode.

Virtual ADX(config)#server real registrar-1 10.1.5.1

Syntax: [no] server real name ip_address


Virtual ADX(config-rs-registrar-1)#port sip


3. Specify a registrar server and a health check method with no DSR. In this scenario, health check messages are sent directly to a real server IP address.

Virtual ADX(config-rs-registrar-1)#port sip sip-registrar health-check-no-dsr

Syntax: port sip [sip-registrar] [health-check-method [ options | register ] ]


• sip-registrar—Identifies the server as a SIP registrar.





Configuring a SIP proxy plus registrar server and enabling health check

Complete the following steps to configure a real SIP proxy plus registrar server and its health check.

1. Configure a real server name and IP address for a registrar/proxy server and enter the real server configuration mode.

Virtual ADX(config)#server real registrar-proxy-server-5 10.1.9.5



Virtual ADX(config-rs-registrar-proxy-server-5)#port sip


NOTE



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3. Specify a registrar proxy server.

Virtual ADX(config-rs-registrar-proxy-server-5)#port sip sip-both-registrar-proxy-server

Syntax: port sip [sip-both-registrar-proxy-server] [health-check-method [ options | register ] ]


• sip-both-registrar-proxy-server—Identifies the server as a SIP registrar server or a proxy server.





Configuring a SIP redirect server and enabling health check

Complete the following steps to configure a real SIP redirect server and its health check.

1. Configure a real server name and IP address for a redirect server and enter the real server configuration mode.

Virtual ADX(config)#server real redirect-server-1 10.1.1.1



Virtual ADX(config-rs-redirect-server-1)#port sip


NOTE


3. Specify a redirect server and a health check method.

Virtual ADX(config-rs-redirect-server-1)#port sip sip-redirect-server health-check-method register

Syntax: port sip [sip-redirect-server] [health-check-method [ options | register ] ]


• sip-redirect-server—Identifies the server as a SIP redirect server.






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Configuring a SIP virtual server

Complete the following steps to configure SIP SLB virtual redirect-proxy servers and virtual proxy domains, and bind real servers to virtual servers.

1. Configure a virtual proxy domain name and IP address for Domain 1 and enter the virtual server configuration mode.

Virtual ADX(config)#server virtual-name-or-ip proxy-domain-1 10.1.6.9

Syntax: [no] server virtual-name-or-ip name ip address

2. Specify the SIP port and SIP switch.

Virtual ADX(config-vs-proxy-domain-1)#port sip sip-switch

Syntax: [no] port sip sip-switch

This command must be used to enable the SIP switch for the virtual port.

NOTE

You can specify the logical SIP port number 5060 or the keyword sip.

3. Configure a domain and specify a SIP domain name and dummy user.

Virtual ADX(config-vs-proxy-domain-1)#port sip sip-user-name sipuser domain-name domain-1

Syntax: [no] port sip [sip-user-name user-name [domain-name domain-name ]]

NOTE

The domain name is optional. If you do not specify a domain name, the server IP address is used.

4. Bind the real SIP registrar servers.

Virtual ADX(config-vs-proxy-domain-1)#bind sip registrar-1 sip registrar-2 sip

Syntax: bind sip registrar-name bind sip registrar-name sip

5. Bind the real SIP proxy servers.

Virtual ADX(config-vs-proxy-domain-1)#bind sip proxy-server-1 sip proxy-server-2 sip

6. Return to global configuration mode.

Virtual ADX(config-vs-proxy-domain-1)#exit

Configuring health check

SIP health check can be performed by either the SIP REGISTER or OPTIONS method. Configure the method according to your needs. The default method is REGISTER.

To configure SIP health check correctly, you must configure the sip-domain-name and dummy-user at the virtual port level. SIP health check can be enabled at Layer 7 using UDP as the transport layer.

NOTE

The Virtual ADX UDP L7 SIP health checks are supported only at regular health checks, i.e. at the real server configuration. It is not supported at element health check.


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SIP SLB over UDP (stateful SLB mode)

SIP SLB over UDP makes SIP stateful and adds the intelligence needed to handle different Caller-ID situations.

SIP stateful basic configuration

1. Configure a real server.

Virtual ADX(config)#server real rs 10.2.2.2

Virtual ADX(config)#port sip sip-proxy-server

Virtual ADX(config)#port sip sip-both-registrar-proxy-server health-check-method register

2. Configure a virtual server.

Virtual ADX(config)#server virtual-name-or-ip sip_vip 10.1.1.1

Virtual ADX(config)#port sip sip-stateful sip-keyfield-call-id

Syntax: [no] port sip sip-stateful [sip-keyfield-call-id | sip-keyfield-via]

3. Configure a SIP stateful port.

Virtual ADX(config)#port sip sip-stateful

Syntax: [no] port sip sip-stateful

4. Bind a virtual server to a real server.

Virtual ADX(config)#bind sip rs sip


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Additional SIP session-specific commands

The following global configuration commands are related to SIP SLB. They will affect all virtual servers with stateful SIP SLB. The commands will not have any effect on the old stateless SIP SLB.

Stateless SIP SLB will still follow the hash table and ages accordingly.

Configuring the maximum number of SIP sessions

Use the server sip session max-sip-sessions command to configure the maximum entries of SIP sessions.

Virtual ADX(config)#server sip session max-sip-sessions 1000000

Syntax: [no] server sip session max-sip-sessions sip-sessions

The sip-sessions variable can be from 10 through a maximum of 3,500,000 sessions.

NOTE

This command requires a reload. Removing this configuration using no command will reset the session to 500,000.

Configuring SIP session age

Use the server sip session session-max-age command to configure the session age in minutes.

Virtual ADX(config)#server sip session session-max-age 50

Syntax: [no] server sip session session-max-age age

The age variable can be from 0 through 60 minutes. The default age is 60 minutes.

Disabling partial SIP support for stateless SIP switching

Use the server sip no-create-forward-l7-session command to configure the Virtual ADX not to create forward SIP sessions for the second leg of the call initiation by real servers, if the real server is bound to a SIP switch-enabled virtual server.

Virtual ADX#server sip no-create-forward-l7-session

Syntax: [no] server sip no-create-forward-l7-session

Clearing SIP sessions

Use the clear server sip session command to clear all SIP sessions load balanced to the specified real-server by setting the age to the maximum age. This command can only be accessed from the management processor (MP).

Virtual ADX#clear server sip session rs1

Syntax: clear server sip session real-server


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Show commands for displaying SIP sessions

NOTE

The show sip session command does not count SIP sessions. Use the show sip server command to display SIP-related real server information.

•

“Showing sip session info”

•

“show sip server”

Showing sip session info

Use the show sip session info command to display information on SIP session usage.

Virtual ADX#show sip session info

Syntax: show sip session info

Virtual ADX#show sip session info slot-9 cup-1 Avail. SIP Ses = 0 total Sip Sessi= 0

Show sip server

Use the show sip server command to display real server-related information.

Virtual ADX#show sip server

Syntax: show sip server

Virtual ADX#show sip server

Avail. SIP sessions = 0 Total SIP sessions = 500000

Server State - 0: disabled, 1:enabled, 2:failed, 3:test, 4:suspect, 5:grace_dn,

6:active

Real Server St CurrConn TotConn CurrSess PeakConn r31 6 28723 344489 28723 91687 r32 6 28722 344505 28722 91632 r33 6 28722 344549 28722 91951 r34 6 28722 344596 28722 91566 r35 6 28723 344702 28723 91870

Debug commands

The following commands and the counters they display are useful for internal debugging purposes.

Showing various SIP counters

Virtual ADX#show sip debug parser

SIP Parser Counters:

PARSER ERR :1 PARSER PKT CORRUPT :4

PARSER MEM ALLOC ERR :0 PARSER MULTI CALLID :0

PARSER ABNORMAL HDR END :0 PARSER PKT HDR TOO LONG :8

PARSER UNKNOWN PKT :21 PARSER CONTENT TOO LONG :0

PARSER CSEQ NOT FOUND :1 PARSER PACKET MALFORMED :0


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Syntax: show sip debug [parser | session| sip-transaction | udp-process]

Debugging SIP sessions

Virtual ADX#show sip debug session

SIP Session Debug Counters

SIP SESSION GET :4381 SIP SESSION GET FAILURE :0

SIP SESS FREE LIST CORUPT :0 SIP SESS INDEX INVALID :0

SIP SESS FINAL FREE :84 SIP SESS DEALLOC :4179

SIP SESS AGED :60 SIP SESS ERR :0

SIP SESS CORRUPT :0 SIP HA AGE SYNC ERR :0

SIP HA AGE SYNC RECV :0 SIP HA AGE SYNC SENT :0

SIP HA OUT OF IPC BUF :0 SIP HA SESS CREAT SENT :0

SIP HA SESS CREAT RECV :0 SIP HA ASP SENT :0

SIP HA DEL MSG RECV :0 SIP HA DEL ATTEMPT RECV :0

SIP HA DEL ATTEMPT SENT :0 SIP HA DELETE MSG SENT :0

SIP HA CREATE EXIST :0 SIP HA DELETE NON-EXIST :3910

Syntax: show sip debug session

Debugging SIP transactions

Virtual ADX#show sip debug sip-tran

SIP Transaction Counters:

TRANSACT ERR :0 TRANSACT ENTRY GET :10585

TRANSACT ENTRY CORRUPTED :0 TRANSACT ENTRY GET FAIL :0

TRANSACT INDEX INVALID :0 TRANSACT FINAL FREED :2828

TRANSACT FROMFLOW NOT FOUND :206 TRANSACT TOFLOW NOT FOUND :354

TRANSACT ENTRY AGED :3533 TRANSACT HEADER INCOMPLETE :0

TRANSACT CONTENT ERR :5 TRANSACT INVALID SIP HEADER :0

TRANSACT PKT TOO BIG :0 TRANSACT PKT DROPPED :5

TRANSACT CLIENT NOT FOUND :0 TRANSACT RESPONSE ENTRY NOT :0

TRANSACT MSG OUTOF BOUND :0

Syntax: show sip debug sip-transaction

Debugging UDP processes

Virtual ADX#show sip debug udp-process

SIP UDP Process Counters:

UDP ERR :0 UDP NO HEADER :0

UDP UNKNOWN PKT :0 UDP PKT TO MP :0

UDP FWD DROP :55 UDP REV DROP :2

UDP NO ACTION :0

Syntax: show sip debug udp-process


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Debugging SIP packet traces

The show sip debug packet-trace command shows the packets with the IP address of either src-or-dest-IP-1 or src-or-dest-IP-2 . The output displays packet processing starting from parsing to forwarding. The command is very useful in debugging; however, it only displays in the BP console not on rconsole.

Syntax: show sip debug packet-trace src-or-dest-IP-1 src-or-dest-IP-2

The following example is a display of session packet processing shown on a BP console.

Virtual ADX#show sip debug packet-trace 2.0.0.1:5060 1.0.0.2:46763

Top branch id: z9hG4bK-19892-1-0

Top Sent By: 1.0.0.2 Top Sent By Port: 46763

-->Starting parsing SIP UDP packet [2.0.0.1:5060->1.0.0.2:46763]

SIP packet header dump:

Packet type: RESPONSE - 2xx

URI: version: SIP/2.0 response code: 200

parse completed: 1 num pkts processed: 0 method: INVITE

VIA header: SIP/2.0/UDP 1.0.0.2:46763;branch=z9hG4bK-19892-1-0

Call ID: 112@1.0.0.2

Cseq: 1 INVITE





Packet type: ACK

URI: sip:brcd@1.0.0. version: SIP/2.0 response code: 0

parse completed: 1 num pkts processed: 0 method: ACK


Max forward: 70

Call ID: 112@1.0.0.2

Cseq: 1 ACK





Packet type: BYE

URI: sip:brcd@1.0.0. version: SIP/2.0 response code: 0

parse completed: 1 num pkts processed: 0 method: BYE


Max forward: 70

Call ID: 112@1.0.0.2

Cseq: 2 BYE





Packet type: RESPONSE - 2xx

URI: version: SIP/2.0 response code: 200

parse completed: 1 num pkts processed: 0 method: BYE


Call ID: 112@1.0.0.2

Cseq: 2 BYE




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This section describes the syntax and usage for each SIP Server Load Balancing command in the real server configuration mode and the virtual server configuration mode.

Real server configuration mode

Use the port sip command in the real server or virtual server configuration mode to configure a proxy, redirect, registrar, or registrar-proxy server. These commands are issued from the real server configuration.

Syntax: port sip {sip-redirect-server | sip-proxy-server | sip-registrar | sip-both-registrar-proxy-server} [health-check-method [options | register]] |


• sip-redirect-server—Identifies the server as a SIP redirect server.

• sip-proxy-server—Identifies the server as a SIP proxy server.

• sip-registrar—Identifies the server as a SIP registrar.

• sip-both-registrar-proxy-server—Identifies the server as a SIP registrar or a proxy server.





Virtual server configuration mode

Use the port sip command in the virtual server configuration mode to configure. The commands are issued from the virtual server configuration.

Syntax: port sip sip-switch | sip-domain-name domain-name

• sip-switch—Enables SIP switching.

• sip-domain-name domain-name —Specifies SIP domain name.

Sample configuration

The following example shows the configuration details for SIP Server Load Balancing.


port sip

port sip sip-both-registrar-proxy-server health-check-method register

port sip keepalive

!


port sip

port sip sip-both-registrar-proxy-server health-check-method register

port sip keepalive

!

server virtual-name-or-ip vs1 10.10.0.100

port sip


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port sip dsr

port sip sip-switch

bind sip rs1 sip rs2 sip


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IPv6 Support for Server Load Balancing

Chapter

8

Overview

NOTE

The Brocade Virtual ADX software release 3.0.00 IPv6 support for SLB applies to IPv6 clients and

IPv6 server communications only.

The commands to configure server load balancing, including configuration of virtual servers, real servers, VIP groups, health check parameters, and others are the same for IPv6 as they are for

IPv4. The existing commands have been enhanced to accept IPv6 addresses. Other than IPv6 addressing, no new commands are necessary for configuring SLB for IPv6 on the Brocade Virtual

ADX.

The following sections shows the configuration steps for an IPv6 SLB configuration.

1. Defining IPv6 real servers.

2. Defining IPv6 virtual servers.

3. Define port characteristics using port profile.

4. Define IP routes.

5. VLAN and tagging definitions.

6. Miscellaneous.

7. Saving the configuration.

8. IPv6 configuration example

An example configuration is shown in

Figure 45

.

Access from the IPv6 client to an IPv6 real server is straight forward and doesn’t require any special processing from the Brocade Virtual ADX.

FIGURE 45 IPv6 Client access


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Defining IPv6 real servers

Defining IPv6 real servers

Virtual ADX(config)#server real rs3 2001:db8::a






Virtual ADX(config)#server real rs4 2001:db8::5






Defining IPv6 virtual servers

Virtual ADX(config)#server virtual vs2 2001:db8::face

Virtual ADX(config-rs-v45)#port http

Virtual ADX(config-rs-v45)#port dns

Virtual ADX(config-rs-v45)#bind http rs3 http rs4 http

Virtual ADX(config-rs-v45)#bind http rs7 http

Virtual ADX(config-rs-v45)#bind dns rs5 dns rs6 dns rs7 dns rs3 dns

Virtual ADX(config-rs-v45)#bind dns rs4 dns

Virtual ADX(config-rs-v45)#exit

Defining port characteristics using port profile


Virtual ADX(config-port-http)#session-sync

Virtual ADX(config-port-http)#tcp

Virtual ADX(config)#exit

Virtual ADX(config)server port 53

Virtual ADX(config-port-dns)#session-sync

Virtual ADX(config-port-dns)#tcp keepalive disable

Virtual ADX(config-port-dns)#udp


Defining IP routes

Virtual ADX(config)#ipv6 route 2001:db8::/64 2001:db8::212:f2ff:fea8:1400



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VLAN and tagging definitions

8

VLAN and tagging definitions

Virtual ADX(config)#vlan 1 name DEFAULT-VLAN by port

Virtual ADX(config-vlan-1)#exit

Virtual ADX(config)#vlan 110 by port

Virtual ADX(config-vlan-10)#tagged ethe 1 to 2

Virtual ADX(config-vlan-10)#untagged ethe 3

Virtual ADX(config-vlan-10)#router-interface ve 10

Virtual ADX(config-vlan-10)#exit

Miscellaneous

Virtual ADX(config)#aaa authentication web-server default local

Virtual ADX(config)#no enable aaa console


Virtual ADX(config)#telnet server

Virtual ADX(config)#username admin password .....

Virtual ADX(config)#snmp-server

Saving the configuration

Virtual ADX(config)#write memory

The IPv6 and IPv4 service definitions can co-exist on the same system.You can define IPv4 VIPs with IPv4 real servers and IPv6 VIPs with IPv6 real servers on the same system.

IPv6 configuration example

An example configuration and SLB session output is shown below.

Example Configuration

!

server source-nat server source-nat-ip 2001:db8:2::20 120 :: port-range 1

!

server real rs1 2001:db8:2::4 port http port http url “HEAD /”

!

server virtual vs1 2001:db8:1::10 port http bind http rs1 http

!

interface ethernet 1 ipv6 address 2001:db8:1::1/120

!

interface ethernet 2 ipv6 address 2001:db8:2::1/120


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IPv6 configuration example

Example SLB session output

Virtual ADX# show session all 0

Session Info:

Flags - 0:UDP, 1:TCP, 2:IP, 3:INT, 4:INVD, H:sessInHash, N:sessInNextEntry

Index Src-IP

===== =============

0

0

2001:db8:2::4

2001:db8:2::3

Dst-IP

=============

2001db8:2::20

2001db8:1::10

S-port D-port Age

====== ====== ===

80

53366

10241

80

32

32

Server

====== rs1 rs1

Flag

========== oSLB 1 H 6 oSLB 1 H 6


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Server-specific Loopback Configurations

Appendix

A

Overview

You can configure loopback addresses on some common types of real servers.

NOTE

The information in this appendix is based on information from the vendors of these servers. For more information, please consult your real server vendor.

Solaris

To configure a loopback address on Solaris, enter the following command.

ifconfig lo0:1 vip-addr netmask net-mask up

You might need to “plumb” the interface first. In this case, enter the following commands. ifconfig lo0:1 plumb ifconfig lo0:1 vip-addr netmask net-mask up

NOTE

The above specified commands applies to the current running configuration only. To make the address permanent so that it is reconfigured following a reboot or power cycle, create the file

/etc/hostname.lo0:1.

NOTE

For Hewlett-Packard (HP) version 11.x, use the May 2000 or later patch.

Linux

To configure a loopback interface on Linux, enter a command such as the following.

ifconfig lo:0 vip-addr netmask net-mask up

NOTE

The ifconfig lo:0 vip-addr netmask net-mask up command applies to the current running configuration only. To make the address permanent so that it is reconfigured following a reboot or power cycle, go to /etc/sysconfig/network-scripts and make a file called ifcfg-lo:0 using ifcfg-lo as a template.


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Windows NT

Windows NT

To configure a loopback interface on Windows NT, you need to configure a new network adapter.

Use the following procedure. This procedure applies to the following products:

• Microsoft Windows 2000 Professional

• Microsoft Windows 2000 Server

• Microsoft Windows 2000 Advanced Server

• Microsoft Windows 2000 Datacenter Server

NOTE

When you add a loopback interface to Windows NT, it sometimes creates a route that has the same address as the loopback interface. You need to delete this route. In come cases, the procedure for deleting the route can include deleting the correct route to the server’s default gateway. When this is the case, you need to add this route back to Windows NT.

Manual installation

1. Click Start, point to Settings, click Control Panel, and then double-click Add/Remove Hardware.

2. Click Add/Troubleshoot a device, and then click Next.

3. Click Add a new device, and then click Next.

4. Click No, I want to select the hardware from a list, and then click Next.

5. Click Network adapters, and then click Next.

6. In the Manufacturers box, click Microsoft.

7. In the Network Adapter box, click Microsoft Loopback Adapter, and then click Next.

8. Click Finish.

After the adapter is installed successfully, you can configure its options manually, as with any other adapter.

NOTE

If the TCP/IP properties are configured to use DHCP (the default), the adapter will eventually use an autonet address (169.254.x.x/16) because it is not actually connected to any physical media.

Unattended installation

Modify the Unattend.txt file using the following example as a guide to install the Microsoft

Loopback adapter.

[NetAdapters]

Adapter01=Params.Adapter01

[Params.Adapter01]

InfID="*msloop" ; Microsoft Loopback Adapter

ConnectionName = "MS Loopback Adapter"

[NetProtocols]

MS_TCPIP=Params.MS_TCPIP

; TCP/IP parameters

; Use parameter values specific to your network


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[Params.MS_TCPIP]

AdapterSections=params.TCPIP.Adapter01

DNS=yes

DNSSuffixSearchOrder=mycorp.com

EnableLMHosts=No

; Adapter Specific TCP/IP parameters

; Use parameter values specific to your network

[params.TCPIP.Adapter01]

SpecificTo=Adapter01

DNSDomain=mycorp.com

DNSServerSearchOrder=192.168.5.251

WINS=no

DHCP=no

IPAddress=192.168.5.10

SubnetMask=255.255.255.0

DefaultGateway=192.168.5.254

Deleting the unwanted routes

In some cases, Windows NT creates a route that has the same address as the loopback interface.

You need to delete this route.

Two methods are shown in this section. If you receive an error message while trying to use the simple method, you need to use the long method instead.

NOTE

Regardless of the method you use, you must repeat the procedure every time the Windows NT server is booted. However, you can create a small batch file to enter these commands and add the batch file to the AT subsystem so that the file runs automatically each time the server is booted.

Simple method

.

The simple method requires you to delete the route that Windows NT creates when you add the loopback interface. The route you need to delete is the one that has the same IP address as the loopback interface.

1. Enter the route print command to display the server’s route table. In this example, the loopback interface has address 192.168.200.106.

C:\>route print

Active Routes:

Network Address Netmask Gateway Address Interface Metric

0.0.0.0 0.0.0.0 192.168.204.254 192.168.200.251 1

10.0.0.0 255.0.0.0 10.0.0.1 10.0.0.1 1

192.168.200.0 255.255.255.0 192.168.200.106 192.168.200.106 1

192.168.200.0 255.255.255.0 192.168.200.251 192.168.200.251 1

192.168.200.106 255.255.255.255 10.0.0.1 10.0.0.1 1

192.168.200.251 255.255.255.255 10.0.0.1 10.0.0.1 1

192.168.200.255 255.255.255.255 192.168.200.251 192.168.200.251 1

224.0.0.0 224.0.0.0 192.168.200.106 192.168.200.106 1

224.0.0.0 224.0.0.0 192.168.200.251 192.168.200.251 1

10.255.255.255 255.255.255.255 192.168.200.251 192.168.200.251 1


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Windows NT

.

2. Delete the route that has the same address as the loopback interface.

C:\>route delete 192.168.200.0 mask 255.255.255.0 192.168.200.106

3. Display the route table again to verify that the unwanted route is gone

C:\>route print

Active Routes:


0.0.0.0 0.0.0.0 192.168.204.254 192.168.200.251 1

10.0.0.0 255.0.0.0 10.0.0.1 10.0.0.1 1

192.168.200.0 255.255.255.0 192.168.200.251 192.168.200.251 1

192.168.200.106 255.255.255.255 10.0.0.1 10.0.0.1 1

192.168.200.251 255.255.255.255 10.0.0.1 10.0.0.1 1

192.168.200.255 255.255.255.255 192.168.200.251 192.168.200.251 1

224.0.0.0 224.0.0.0 192.168.200.106 192.168.200.106 1

224.0.0.0 224.0.0.0 192.168.200.251 192.168.200.251 1

10.255.255.255 255.255.255.255 192.168.200.251 192.168.200.251 1

Long method

.

The long method, like the short method, requires you to delete the route that Windows NT creates when you add the loopback interface. However, what makes this method is long is that in some cases, when the route table has more than one route in the network that contains the loopback interface, the route delete command deletes the wrong route. In this case, you need to enter the command again to delete the route that has the loopback address, then re-add the other route.

1. Enter the route print command to display the server’s route table. In this example, the loopback interface has address 192.168.200.106. Notice that the route table also contains another route (192.168.200.250) in the same network. The 192.168.200.250 route is the gateway route and needs to stay in the route table.

C:\users\default>route print

Active Routes:


0.0.0.0 0.0.0.0 192.168.200.254 192.168.200.250 1

10.0.0.0 255.0.0.0 10.0.0.1 10.0.0.1 1

192.168.200.0 255.255.255.0 192.168.200.250 192.168.200.250 1

192.168.200.0 255.255.255.0 192.168.200.106 192.168.200.106 1

192.168.200.106 255.255.255.255 10.0.0.1 10.0.0.1 1

192.168.200.250 255.255.255.255 10.0.0.1 10.0.0.1 1

192.168.200.255 255.255.255.255 192.168.200.106 192.168.200.106 1

224.0.0.0 224.0.0.0 192.168.200.250 192.168.200.250 1

224.0.0.0 224.0.0.0 192.168.200.106 192.168.200.106 1

10.255.255.255 255.255.255.255 192.168.200.106 192.168.200.106 1

2. Enter the route delete command to delete the unwanted 192.168.200.106 route.

C:\users\default>route delete 192.168.200.0 mask 255.255.255.0

192.168.200.106


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Windows NT

A

3. Display the route table again to verify the results. In this example, Windows NT deletes the first

192.168.200.x route in the table instead of deleting the route you want to delete. If this occurs

when you are performing this procedure, go to step 4 . Otherwise, you are finished with this

procedure.


Active Routes:


0.0.0.0 0.0.0.0 192.168.200.254 192.168.200.250 1

10.0.0.0 255.0.0.0 10.0.0.1 10.0.0.1 1

192.168.200.0 255.255.255.0 192.168.200.106 192.168.200.106 1

192.168.200.106 255.255.255.255 10.0.0.1 10.0.0.1 1

192.168.200.250 255.255.255.255 10.0.0.1 10.0.0.1 1

192.168.200.255 255.255.255.255 192.168.200.106 192.168.200.106 1

224.0.0.0 224.0.0.0 192.168.200.250 192.168.200.250 1

224.0.0.0 224.0.0.0 192.168.200.106 192.168.200.106 1

255.255.255.255 255.255.255.255 192.168.200.106 192.168.200.106 1

4. Enter the route delete command again to delete the unwanted route.

C:\users\default>route delete 192.168.200.0 mask 255.255.255.0

192.168.200.106

5. Display the route table again to verify the results. In this example, none of the 192.168.200.x routes remain in the table.


Active Routes:


0.0.0.0 0.0.0.0 192.168.200.254 192.168.200.250 1

10.0.0.0 255.0.0.0 10.0.0.1 10.0.0.1 1

192.168.200.106 255.255.255.255 10.0.0.1 10.0.0.1 1

192.168.200.250 255.255.255.255 10.0.0.1 10.0.0.1 1

192.168.200.255 255.255.255.255 192.168.200.106 192.168.200.106 1

224.0.0.0 224.0.0.0 192.168.200.250 192.168.200.250 1

224.0.0.0 224.0.0.0 192.168.200.106 192.168.200.106 1

10.255.255.255 255.255.255.255 192.168.200.106 192.168.200.106 1

6. Enter the route add command to re-add the gateway route.

C:\users\default>route add 192.168.200.0 mask 255.255.255.0 192.168.200.250


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Windows NT

7. Display the route table again to verify that the table contains the gateway route but does not contain a route with the loopback address.


Active Routes:


0.0.0.0 0.0.0.0 192.168.200.254 192.168.200.250 1

10.0.0.0 255.0.0.0 10.0.0.1 10.0.0.1 1

192.168.200.0 255.255.255.0 192.168.200.250 192.168.200.250 1

192.168.200.106 255.255.255.255 10.0.0.1 10.0.0.1 1

192.168.200.250 255.255.255.255 10.0.0.1 10.0.0.1 1

192.168.200.255 255.255.255.255 192.168.200.106 192.168.200.106 1

224.0.0.0 224.0.0.0 192.168.200.250 192.168.200.250 1

224.0.0.0 224.0.0.0 192.168.200.106 192.168.200.106 1

10.255.255.255 255.255.255.255 192.168.200.106 192.168.200.106 1


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SLB Show and Debug Commands

Appendix

B

Using show source-ip

source ip

[

real-server ip

| all]

The show source-ip source-ip command displays the IP information, free ports, owner, start, and end for port pools for a specific source IP.

The show source-ip source ip real-server-ip command displays the free ports, owner, start, and end for port pools for the specified source IP addresses and real server.

The show source-ip source ip all command all displays the free ports, owner, start, and end for port pools for the specified source IP addresses for all real servers.

Virtual ADX#show source-ip source ip [ real-server ip | all]

Example

Virtual ADX#show source-ip 10.4.4.101 all

Source IP information

*********************

Source IP: 10.4.4.101

flt: Yes standby: No intf ip: No

Real server: real-rs-8.10 (10.8.8.10)

MMS: h: 0 t: 0 m: 23b4fb3c T: 642 f: 642

RTSP: h: 0 t: 0 m: 23b51b54 T: 384 f: 384

NORM: h: 0 t: 0 m: 23b34b24 T: 9216 f: 9216


MMS: h: 0 t: 0 m: 23b53b6c T: 642 f: 642

RTSP: h: 0 t: 0 m: 23b55b84 T: 384 f: 384

NORM: h: 0 t: 0 m: 280c1d08 T: 9216 f: 9216


MMS: h: 0 t: 0 m: 23b58114 T: 642 f: 642

RTSP: h: 0 t: 0 m: 23b5a12c T: 384 f: 384

NORM: h: 0 t: 0 m: 280dcd20 T: 9216 f: 9216

NOTE

If the show source-ip command displays that the IP is a per-real-srcip, then you should use the show source-ip source-ipreal-server ip command to view the port allocation and usage information, because the port allocation will be from the real server pool.


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Using the show session all command

Using the show session all command

Use the show session command (available at the BP console only) to determine if the sessions have been created correctly.


Virtual ADX1/1#show session all 0

Session Info:

Flags-

0:UDP, 1:TCP, >:fwdSess, +:userCntFlgSet, D:sessInDelQ, F:fin_setFlg, A:acked

* before age indicates that the static bit is set

Index Src-IP Dst-IP S-port D-port Age Serv Flags

===== ====== ====== ====== ====== === ==== ==========

0 10.0.0.5 10.1.1.36 5 80 *0 n/a SLB1 #

1 10.0.0.5 10.1.1.99 5 80 *0 n/a SLB1 #

2 10.1.1.15 10.1.1.79 80 10242 32 n/a OPT1 #

3 10.1.1.15 10.1.1.79 80 10242 - rest SLB1 A

4 10.1.1.42 10.1.1.99 1333 80 33 n/a OPT1> #

5 10.1.1.42 10.1.1.99 1333 80 - rest SLB1>+

6 10.1.1.15 10.0.0.1 1 1 *60 n/a SLB1 #

7 10.1.1.66 10.0.0.1 1 1 *60 n/a SLB1 #

In the above example, 10.1.1.42 is the client and 10.1.1.99 is the VIP address. The IP address

10.1.15 is the real server and 10.1.1.79 is the source NAT IP.

NOTE

In the reverse session, the port 10242 has been allocated from the pool of real server 10.1.1.15.

You can verify the information by using the show source-ip command.

.

Virtual ADX#show source-ip 10.1.1.79 10.1.1.15

Source IP information

*********************

Source IP: 10.1.1.79

Real server: rest (10.1.1.15) flt: Yes standby: No intf ip: No port-range: 1 for ssl: No per-real-srcip: Yes

NORM: h: 3 t: 2 m: 23b33b24 T: 27648 f: 27647

The output shows that of a total of 27648 ports, one port has been allocated and 27467 are still available.


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Using the source-ip-debug command

B

Using the source-ip-debug command

NOTE

This command should only be used for debugging purposes, because enabling it could impact performance.

You can configure the following command to enable debugging for source IP.

Virtual ADX(config)#source-ip-debug

Syntax: [no] source-ip-debug

Using the debug filter command

The Brocade Virtual ADX debug filter is a packet capture utility that captures packets at the

Brocade Virtual ADX itself based on user-defined filters. The captured packets are stored in a capture buffer and it is possible to view the packets on-screen or to transfer them to a TFTP server to have a look at them offline. The Brocade Virtual ADX offers the possibility to store packet captures in PCAP format. This simplifies the work dramatically due to the fact that users are able to use PCAP based tools to work with the packet captures taken at the Brocade Virtual ADX.

Using the packet capture utility

You have to do the following to use the Brocade Virtual ADX packet capture utility (debug filter):

1. enter utility

2. configure capture buffer

3. specify packet size to capture

4. specify filters

5. apply filters

6. start capturing process

7. stop capturing process

8. view captured packets

Enter Utility

To enter the debug filter, enter the following commands:

Virtual ADX> ena

Virtual ADX# debug filter

Virtual ADX(debug-filter)#


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Configuring Capture Buffer

You have to specify the size of the capture buffer in kilobytes. To set the buffer size do the following:

Virtual ADX(debug-filter)# buffer-size 1024

Syntax: buffer-size kilobytes

To display the buffer size do the following:

Virtual ADX(debug-filter)# buffer-size 1024

Syntax: buffer-size kilobytes

Virtual ADX(debug-filter)# show buffer-size

Capture buffer size: 1048567 bytes

Specify packet size to capture

You can specify the number of bytes from a captured packet that are getting stored in the capture buffer. It is also possible to store the entire packet.

To set the amount of bytes to store do the following:

Virtual ADX(debug-filter)# packet-size 128

Syntax: packet-size bytes | whole

The whole variable specifies that the entire packet needs to be stored in the capture buffer.

To show the currently configured packet size:

Virtual ADX(debug-filter)# show packet-size

Max bytes stored from a filtered pkt: 128

Specify filter(s)

You specify the packets to store in the capture buffer by configuring one or more filter IDs. A filter ID consists of a set of filters that specify the attributes of packets to be stored in the capture buffer.

You can configure up to 16 filter IDs.

Within a filter ID, you can specify filters for Layer 2 - 4 information in a packet. In addition, you can set up filters to capture packets that contain a specified pattern within the packet.

By default, a filter ID is configured to match any packet. Within a filter ID, all the filters must match a received packet in order for the packet to be captured. The filters not explicitly configured have

"don't care" values, which are ignored during the matching process.

To specify the filter with ID 1:

Virtual ADX(debug-filter)#specify 1

Virtual ADX(debug-filter-spec-1)#

Syntax: specify filter-id

You are able to specify filter settings at the filter ID configuration level. It is possible as well to display the current settings.


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B

Table 36 displays the Ethernet Filter settings.

TABLE 36 Ethernet Filter Settings

CLI Command Filter Type mac bcast mac dest mac-address mac mcast mac src mac-address mac type type-in-hex

Ethernet broadcast packets

Packets with the specified destination MAC address

Ethernet multicast packets

Packets with the specified source MAC address

Packets of the specified Layer 3 type

Table 37

displays the IP Filter settings.

TABLE 37 IP Filter Settings

CLI Command Filter Type ip bcast ip dest ip-address ip mcast ip protocol protocol-in-hex ip src ip-address

IP broadcast packets

Packets with the specified destination IP address

IP multicast packets

Packets with the specified Layer 4 protocol

Packets with the specified source IP address

Table 38 displays the TCP Filter settings.

TABLE 38 TCP Filter Settings

CLI Command Filter Type tcp src port-number tcp dest port-number tcp syn tcp reset tcp fin tcp ack tcp push tcp urgent

Packets with the specified source TCP port

Packets with the specified destination TCP port

TCP packets with the SYN flag on

TCP packets with the RST flag on

TCP packets with the FIN flag on

TCP packets with the ACK flag on

TCP packets with the PSN flag on

TCP packets with the URG flag on

Table 39 displays the UDP Filter settings.

TABLE 39 UDP Filter Settings

CLI Command Filter Type udp src port-number udp dest port-number tcp syn tcp reset tcp fin

Packets with the specified source UDP port

Packets with the specified destination UDP port

TCP packets with the SYN flag on

TCP packets with the RST flag on

TCP packets with the FIN flag on


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B


TABLE 39 UDP Filter Settings

CLI Command Filter Type tcp ack tcp push tcp urgent

TCP packets with the ACK flag on

TCP packets with the PSN flag on

TCP packets with the URG flag on

Pattern matching filter settings

You can set up a filter to capture packets that contain a pattern of a specified length, starting from a given offset from the beginning of the packet.

Example:

Virtual ADX(debug-filter-spec-1)#pattern 24 2 1023

Syntax: pattern offset length pattern-in-hex

The offset variable is the number of bytes from the start of the packet.

The length variable is the length of the pattern in bytes. You can specify between 1 - 32 bytes.

The pattern-in-hex variable is the pattern to match. The length of the pattern must be equal to the number of bytes specified with the length variable.

Example:

Create a filter to look for every packet from source IP 192.168.8.1 going to destination IP

192.168.8.222 - destination port 80:

Virtual ADX(debug-filter-spec-1)#ip src 192.168.8.1

Virtual ADX(debug-filter-spec-1)#ip dest 192.168.8.222

Virtual ADX(debug-filter-spec-1)#tcp dest 80

To show the currently applied settings for the filter, use the show command:

Virtual ADX(debug-filter-spec-1)#show

Filter-ID: 1

MAC filters:

Src MAC : ANY

Dest MAC : ANY

MAC Type : ANY

IP filters:

Src IP : 192.168.8.1

Dest IP : 192.168.8.222

Protocol : ANY

TCP filters:

Src port: ANY

Dest port: 80

Flags : None

UDP filters:

Src port: ANY

Dest port: ANY

HTTP filters:

Url : ANY

Cookie : ANY

Pattern filters:

Pattern : ANY


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B

Syntax: show

Use reset at the filter ID configuration level to restore the filter IDs default settings (match ALL):

Virtual ADX(debug-filter-spec-1)#reset

Syntax: reset

Use exit to leave the filter ID configuration level.

Virtual ADX(debug-filter-spec-1)#exit

Virtual ADX(debug-filter)#

Syntax: exit

It is also possible to display the setting for a filter ID at the "debug filter" level. This is shown in the following example:

Virtual ADX(debug-filter)#show 1

Filter-ID: 1

MAC filters:

Src MAC : ANY

Dest MAC : ANY

MAC Type : ANY

IP filters:

Src IP : 192.168.8.1

Dest IP : 192.168.8.222

Protocol : ANY

TCP filters:

Src port: ANY

Dest port: 80

Flags : None

UDP filters:

Src port: ANY

Dest port: ANY

HTTP filters:

Url : ANY

Cookie : ANY

Pattern filters:

Pattern : ANY

Syntax: show filter-id

Apply filter(s)

It is possible to define multiple filters like the one shown above - a filter is a set of matching criteria to select packets. A filter takes effect when you apply it. A filter ID should be applied globally or on an individual port. You can apply a filter ID so that it filters inbound traffic only, outbound traffic only, or both.

The following command will apply filter 1 globally for inbound and outbound traffic:

Virtual ADX(debug-filter)# apply 1

Syntax: apply filter-id


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You can apply multiple filter IDs and specify an and/or relationship between them. For example, to apply filter IDs 1 and 2, enter the following command. Packets that match the filters in both filter

IDs are stored in the capture buffer.

Virtual ADX(debug-filter)# apply "1 and 2"

This is useful to create more complex filtering rules. A single filter ID is not able to cover a communication from host A to host B because it is necessary to cover the "flow" from host A to host

B and the "flow" from host B to host A.

Example:

Create a filter logic to look for every packet of the communication in between the client with IP

192.168.8.1 and the virtual server with IP 192.168.8.222 at port 80:

Virtual ADX(debug-filter)# sp 1



Virtual ADX(debug-filter-spec-1)#tcp dest 80


Virtual ADX(debug-filter)#sp 2



Virtual ADX(debug-filter-spec-2)#tcp src 80


Virtual ADX(debug-filter)# apply "1 or 2"

The filter ID 1 is going to hit for all packets from the client to the virtual server and filter ID 2 is going to hit for the return traffic. One of these filter IDs need to be true to be sure it is part of the communication we are looking for.

It is also possible to create more complex filter expressions as shown below:

To apply filter IDs 1, 2, and 3 so that packets must match the filters in 1 and match the filters in either 3 or 4, enter the following command:

Virtual ADX(debug-filter)#apply "(1 and (3 or 4))"

To view the currently applied expressions:

Virtual ADX(debug-filter-all-all)#show apply

Filter ID apply expression: ( 1 and ( 3 or 4 ) )

Syntax: show apply

Start Capturing Process

You are able to start the capturing process as soon as you have done all the steps mentioned above. Once you start the packet capture utility, filtered packets are stored in the capture buffer and are available for viewing until you restart the utility.

To start the packet capture utility, enter the following command:

Virtual ADX (debug-filter)# start

Syntax: start

The packet capturing process will run until the configured buffer is full or until it is stopped manually.


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Stop Capturing Process

You can stop the packet capture utility with the following command:

Virtual ADX(debug-filter)# stop

Number of packets captured: 126

Syntax: stop

View Captured Packets

First of all you have to select one of the places where packets are captured. JetCore based devices offer two locations:

• MP = Management Processor

• BP = Barrel Processor

Use the view command to select the processor you would like to choose:

To select BP 2 of the WSM module in slot 1:

Virtual ADX(debug-filter)# view bp 1 2

Virtual ADX(debug-filter-1-2)#

To select the MP:

Virtual ADX(debug-filter)# view mp

Virtual ADX(debug-filter-mp)#

Syntax: view [mp | bp slot-number cpu-number ]

You now have multiple options and you might want to use the summary command to see a summary of all packets captured at the chosen location.

Syntax: summary

It is also possible to have a close look at a single packet using the hex-dump or ascii-dump command:

Syntax: ascii-dump packet-number

Syntax: hex-dump packet-number

The example below includes some example outputs which might help to understand how to use the commands.

"debug filter" example

Test network: client (192.168.8.100) ---- port 15 (192.168.8.1) Brocade Virtual ADX (192.168.9.1) port 3 ---

(192.168.9.101) real server

Virtual server @ Virtual ADX: 192.168.8.222 offering HTTP service

Brocade Virtual ADX real and virtual server configuration: server real rs101 192.168.9.101

port http port http url "HEAD /"

!


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!

server virtual vs222 192.168.8.222

port http bind http rs101 http

Task:

Get a packet capture of an HTTP request coming from the client IP 192.168.8.100 to the virtual server 192.168.8.222 including the packets going to the real server 192.168.9.101.

The source IP of the client request is 192.168.8.100 and the destination TCP port is 80. The backend traffic is as well using the client IP 192.168.8.100 because we do not have source-nat configured. The real servers service port is 80 as well. The return/reply traffic is going to use

192.168.8.100 as destination IP and it is using the source TCP port 80.

Filters to configure:

1. from source IP 192.168.8.100 to destination port 80 TCP

2. to destination IP 192.168.8.100 from source port 80 TCP

Interesting traffic will hit the first or second filter.

CLI commands/outputs and comments:

Enter debug filter utility: telnet@Virtual ADX>ena

No password has been assigned yet...

telnet@Virtual ADX#debug filter

Configure buffer-size and packet-size to store in buffer: telnet@Virtual ADX(debug-filter)#buffer-size 4096 telnet@Virtual ADX(debug-filter)#packet-size whole

Create filter 1 and filter 2: telnet@Virtual ADX(debug-filter)#sp 1 telnet@Virtual ADX(debug-filter-spec-1)#reset telnet@Virtual ADX(debug-filter-spec-1)#ip src 192.168.8.100

telnet@Virtual ADX(debug-filter-spec-1)#tcp dest 80 telnet@Virtual ADX(debug-filter-spec-1)#exit telnet@Virtual ADX(debug-filter)#sp 2 telnet@Virtual ADX(debug-filter-spec-2)#reset telnet@Virtual ADX(debug-filter-spec-2)#ip dest 192.168.8.100

telnet@Virtual ADX(debug-filter-spec-2)#tcp src 80 telnet@Virtual ADX(debug-filter-spec-2)#exit

Apply filters using OR as operator: telnet@Virtual ADX(debug-filter)#apply 1or2

Start capturing process: telnet@Virtual ADX(debug-filter)#start

SENT REQUEST FROM TEST CLIENT 192.168.8.100 NOW

Stop capturing process: telnet@Virtual ADX(debug-filter)#stop


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Check ALL BPs to find the BP responsible for the test client: telnet@Virtual ADX(debug-filter)#view bp 1 1 telnet@Virtual ADX(debug-filter-1-1)#sum telnet@Virtual ADX(debug-filter-1-1)#view bp 1 2 telnet@Virtual ADX(debug-filter-1-2)#sum telnet@Virtual ADX(debug-filter-1-2)#view bp 1 3 telnet@Virtual ADX(debug-filter-1-3)#sum

NOTHING SO FAR - CHECK THE NEXT AND LAST PROCESSOR TALKING ABOUT THE ADX1016-4: telnet@Virtual ADX(debug-filter-1-3)#view bp 1 4 telnet@Virtual ADX(debug-filter-1-4)#sum

Number of packets captured: 20 pkt:1 IN len:112 TCP :3881 ->80 Seq:4047880146 Ack SYN pkt:2 OUTlen:138 TCP :3881 ->80 Seq:4047880146 Ack SYN pkt:3 IN len:112 TCP :80 ->3881 Seq:2434401979 Ack:4047880147 SYN ACK pkt:4 OUTlen:138 TCP :80 ->3881 Seq:2434401979 Ack:4047880147 SYN ACK pkt:5 IN len:106 TCP :3881 ->80 Seq:4047880147 Ack:2434401980 ACK pkt:6 OUTlen:132 TCP :3881 ->80 Seq:4047880147 Ack:2434401980 ACK pkt:7 IN len:152 TCP :3881 ->80 Seq:4047880147 Ack:2434401980 ACK PSH pkt:8 OUTlen:178 TCP :3881 ->80 Seq:4047880147 Ack:2434401980 ACK PSH pkt:9 IN len:106 TCP :80 ->3881 Seq:2434401980 Ack:4047880199 ACK pkt:10 OUTlen:132 TCP :80 ->3881 Seq:2434401980 Ack:4047880199 ACK pkt:11 IN len:423 TCP :80 ->3881 Seq:2434401980 Ack:4047880199 ACK PSH pkt:12 OUTlen:449 TCP :80 ->3881 Seq:2434401980 Ack:4047880199 ACK PSH pkt:13 IN len:106 TCP :3881 ->80 Seq:4047880199 Ack:2434402303 ACK pkt:14 OUTlen:132 TCP :3881 ->80 Seq:4047880199 Ack:2434402303 ACK pkt:15 IN len:106 TCP :3881 ->80 Seq:4047880199 Ack:2434402303 ACK FIN pkt:16 OUTlen:132 TCP :3881 ->80 Seq:4047880199 Ack:2434402303 ACK FIN pkt:17 IN len:106 TCP :80 ->3881 Seq:2434402303 Ack:4047880200 ACK FIN pkt:18 OUTlen:132 TCP :80 ->3881 Seq:2434402303 Ack:4047880200 ACK FIN pkt:19 IN len:106 TCP :3881 ->80 Seq:4047880200 Ack:2434402304 ACK pkt:20 OUTlen:132 TCP :3881 ->80 Seq:4047880200 Ack:2434402304 ACK

The test client hits BP 1 4 and the summary is showing 20 packets related to the test request.

Packet #1 is the incoming TCP SYN packet, packet #2 is the same SYN packet but it is behind the

Brocade Virtual ADX (going to the real server). Each packet is visible twice because it exists before and after the Brocade Virtual ADX (before SLB and after SLB).

The client HTTP request is part of packet #7 (after the 3-way handshake): telnet@Virtual ADX(debug-filter-1-4)#ascii 7

Packet 7 captured at Oct 26 17:00:24 ; Packet size is 152(0x0098) bytes

In port: 15 fpga optimized: No

Ethernet Version II

Address: 0024.81f7.2f8f ---> 021b.ed3c.cb60

Ethernet II Protocol Type: IP

Internet Protocol

Version(MSB 4 bits): 4

Header length(LSB 4 bits): 5 (32-bit word)

Service Type: 0x00

Total length: 92 (Octets)

Fragment ID: 7207

Flags summary: 0x40


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0... .... = Reserved

.1.. .... = Do not fragment

..0. .... = Last fragment

Fragment offset(LSB 13 bits): 0 (0x00)

Time to live: 128 seconds/hops

IP protocol type: TCP (0x06)

Checksum: 0x4be2

IP address: 192.168.8.100

---> 192.168.8.222

No option

Transmission Control Protocol

Port 3881 ---> 80

Sequence Number: 4047880147

Acknowledgement Number: 2434401980

Header Length(MSB 4 bits): 5 (32-bit word)

Reserved(LSB 4 bits): 0

Code: 0x18

RES: 0... ....

CON: .0.. ....

URG: ..0. ....

ACK: ...1 ....

PSH: .... 1...

RST: .... .0..

SYN: .... ..0.

FIN: .... ...0

Window: 64000

Checksum: 0xe90f

Urgent Pointer: 0x0000

Data:

0000: 47 45 54 20 2f 20 48 54 54 50 2f 31 2e 31 0d 0a | GET / HTTP/1.1..

0010: 48 6f 73 74 3a 20 31 39 32 2e 31 36 38 2e 38 2e | Host: 192.168.8.

0020: 32 32 32 0d 0a 41 63 63 65 70 74 3a 20 2a 2f 2a | 222..Accept: */*

0030: 0d 0a 0d 0a 00 00 00 00 00 00 00 00 00 00 | ..............

The packet arrived via port 15 (client facing) and the IP header is showing the following:

• source IP: 192.168.8.100

• destination IP: 192.168.8.222

This is a packet coming from the client to the virtual server. Packet #8 is the same packet BUT on the way to the real server (after SLB): telnet@Virtual ADX(debug-filter-1-4)#ascii 8

Packet 8 captured at Oct 26 17:00:24 ; Packet size is 178(0x00b2) bytes

Out port: 3 fpga optimized: No

Ethernet Version II

Address: 001b.ed3c.cb62 ---> 021b.ed3c.cb60

Ethernet II Protocol Type: IP

Internet Protocol

Version(MSB 4 bits): 4

Header length(LSB 4 bits): 5 (32-bit word)

Service Type: 0x00

Total length: 92 (Octets)

Fragment ID: 7207

Flags summary: 0x40

0... .... = Reserved

.1.. .... = Do not fragment

..0. .... = Last fragment


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Fragment offset(LSB 13 bits): 0 (0x00)

Time to live: 128 seconds/hops

IP protocol type: TCP (0x06)

Checksum: 0x4be2

IP address: 192.168.8.100 ---> 192.168.9.101

No option

Transmission Control Protocol

Port 3881 ---> 80

Sequence Number: 4047880147

Acknowledgement Number: 2434401980

Header Length(MSB 4 bits): 5 (32-bit word)

Reserved(LSB 4 bits): 0

Code: 0x18

RES: 0... ....

CON: .0.. ....

URG: ..0. ....

ACK: ...1 ....

PSH: .... 1...

RST: .... .0..

SYN: .... ..0.

FIN: .... ...0

Window: 64000

Checksum: 0xe90f

Urgent Pointer: 0x0000

Data:

0000: 47 45 54 20 2f 20 48 54 54 50 2f 31 2e 31 0d 0a | GET / HTTP/1.1..

0010: 48 6f 73 74 3a 20 31 39 32 2e 31 36 38 2e 38 2e | Host: 192.168.8.

0020: 32 32 32 0d 0a 41 63 63 65 70 74 3a 20 2a 2f 2a | 222..Accept: */*

0030: 0d 0a 0d 0a 00 00 00 00 00 00 00 00 00 00 00 00 | ................

0040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 | ................

0050: 00 00 00 00 00 00 00 00 | ........

The packet is leaving via port 3 (real server facing) and the IP header is showing the following:

• source IP: 192.168.8.100

• destination IP: 192.168.9.101

This is a packet coming from the client going to the real server.

Saving captured packets

After you captured packets and viewed them with the summary command, you can save them by performing the following steps:

Virtual ADX(debug-filter-1-1)#pcap save

ASCII string file name

<cr>

Virtual ADX(debug-filter-1-1)#pcap save a1 preparing pcap data file, please wait...

.Done

Virtual ADX(debug-filter-1-1)#end

Virtual ADX#

[detached]

[root@Virtual ADX]# cd /opt/ADX/pcap

[root@Virtual ADX pcap]# ls a1.cap*


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Displaying global Layer 4 Brocade Virtual ADX configuration

Now you can copy the file to a TFTP server. Use one of the following methods:

• From a Linux console:

[root@Virtual ADX pcap]# tftp -p -l a1.cap -r z1.cap 10.24.132.85

a1.cap is the local file and z1.cap is the remote file name.

• From the CLI or Management console:

Virtual ADX#copy file tftp 10.24.132.85 b1.cap /opt/ADX/pcap/a1.cap

b1.cap is the remote file name and a1.cap is the local file name.

Helpful tips

It is a good practice to RESET a filter ID as soon as you want to define the filter. Filter ID settings do survive until the unit is getting rebooted. A reset ensures the filter is back at the default which implies "match ALL": telnet@Virtual ADX(debug-filter)#sp 2 telnet@Virtual ADX(debug-filter-spec-2)# reset

The Brocade Virtual ADX is also able to store traces in PCAP format.

The Brocade Virtual ADX offers up to 32 MB of capturing space.

NOTE

To capture ingress and egress packets on the Brocade Virtual ADX using the MAC filter, specify the internal base MAC instead of the chassis MAC. You can display the internal base MAC by using the show server debug command.


To display global Layer 4 Brocade Virtual ADX configuration information, enter the following command.

Virtual ADX(config)#show server global

Server Load Balancing - global parameters

Predictor = least-conn

Force-deletion = 0

Reassign-threshold = 20

Reassign-limit = 3

Ping-interval = 2

Ping-retries = 4

TCP-age = 30

UDP-age = 5

Sticky-age = 30

TCP-syn-limit = 65535

TCP-total conn = 4233

Unsuccessful conn = 0

ICMP-message = Disabled

Syntax: show server global


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Table 40 lists the displayed information.

TABLE 40 Global layer 4 configuration information

Field Description

SLB Parameters

Predictor

Force-deletion

Reassign-threshold

Reassign-limit

The load balancing metric in effect on the Brocade Virtual ADX. The predictor can be one of the following:

• least-conn (least connections)

• round-robin

• weighted-round-robin

• weighted

• enhanced-weighted

• least-local-conn (least local connections)

• least-local-sess (least local sessions)

The default is least-conn.

You can assign these metrics on a global basis and an individual virtual server basis.

For more information, refer to “Load-balancing predictor” on page 8.

To change the predictor (globally or locally), refer to

“Changing the

Load-Balancing Predictor Method” on page 21.

The state of the force shutdown option. This option immediately shuts down a server or service instead of waiting for existing connections to end before shutting the server or service down. The state can be one of the following:

•

0 – Disabled

•

1 – Enabled

The number of contiguous inbound TCP-SYN packets sent to the server that the server has not responded to.

The TCP SYN-ACK counter increments only when acknowledgments are not received. Each time an expected TCP SYN-ACK is received, the counter is cleared.

The default reassign threshold is 20 unacknowledged TCP SYN-ACKs.

The value can be from 6 through 4000. To change the reassign

threshold, refer to “Reassign threshold” on page 220

NOTE: You can modify this parameter to help minimize vulnerability to

TCP SYN attacks.

The number of missed TCP SYN packets the Brocade Virtual ADX will accept before moving an inbound connection attempt to another server.

Layer 3 Health Check Parameters

Ping-interval

Ping-retries

How often the Brocade Virtual ADX sends a Layer 3 IP ping to test the basic health and reachability of the real servers. When enabled, this parameter specifies the interval for the pings. To change the interval,

refer to “Modifying the ping interval and ping retries” on page 161.

The number of times that the Brocade Virtual ADX resends a ping to a real server that is not responding. Allowed values are from 2 through 10,

and the default is 4. To change this parameter, refer to “Modifying the ping interval and ping retries” on page 161.

If the server still does not respond after the last retry, the Brocade

Virtual ADX marks the server FAILED and removes it from the load balancing rotation.


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TABLE 40 Global layer 4 configuration information (Continued)

Field Description

Global TCP/UDP Parameters

TCP-age

UDP-age

Sticky-age

TCP-syn-limit

The number of minutes the Brocade Virtual ADX allows a TCP connection to remain unused before closing the connection. The default is 30. To

change this parameter, refer to “Configuring TCP age” on page 239.

The value shown here is the global value. You can override this value for an individual TCP/UDP port by modifying its port profile. Refer to


The number of minutes the Brocade Virtual ADX allows a UDP connection to remain unused before closing the connection. The default

is 5. To change this parameter, refer to “Configuring UDP age” on page 239.

The value shown here is the global value. You can override this value for an individual TCP/UDP port by modifying its port profile. Refer to


The number of minutes a sticky server connection can remain inactive before aging out. The default is 5.

The maximum number of TCP SYN connections per second the Brocade

Virtual ADX is allowed to send to the real server. The default is 65535.

You can guard against TCP SYN attacks by changing this parameter to a

lower value. Refer to “Limiting the maximum number of TCP SYN requests” on page 110.

TCP Connections Counters

TCP-total conn

Unsuccessful conn

The total number of TCP connections the Brocade Virtual ADX is currently managing.

The number of client requests for a TCP port that the Brocade Virtual

ADX could not fulfill because the server was busy or down, or because the port was not configured on the server.

ICMP Message Feature State

ICMP-message The state of the ICMP message feature. The state can be one of the following:

•

Disabled – The Brocade Virtual ADX does not send ICMP

“Destination Unreachable” messages to a client that requests an

HTTP port that is on a busy or down server or that is not configured on the server. This is the default.

•

Enabled – The Brocade Virtual ADX sends ICMP “Destination

Unreachable” messages to clients when the requested HTTP port is not available or not configured.

To change the state of this feature, refer to

“Sending ICMP Port

Unreachable or Destination Unreachable messages” on page 113.


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Using the show server real command

Use the show server real command to view real IP addresses as well as configuration information and basic statistics for all the real servers configured on the Brocade Virtual ADX.

To display configuration information for a specific real server, enter the show server real command using its server name or IP address such as in the following example:

Virtual ADX(config)#show server real r6

Real Servers Info

========================



HLD:held-down

Name: r6 State: Active Cost: 0 IP:400::457: 1

Mac: 0000.855d.e2cd Weight: 1/1 MaxConn: n/a

SrcNAT: not-cfg, not-op DstNAT: not-cfg, not-op Serv-Rsts: 0

Rx throughput: 190 Kbps Tx throughput: 340 Kbps tcp conn rate:udp conn rate = 9:0

Use local conn : No


---- -- -- ------- ------- ------- ------- -------- -------- ---default UNB 0 0 0 0 0 0 0 0 http ACT 0 20 970 4398 4847 563498 607932 0

Server Total 0 970 4398 4847 563498 607932 0

Syntax: show server real server-name | ip-address

The server-name variable specifies the real server by name. Alternatively, the ip-address variable may be used to specify the real server by its IP address.

Table 41 describes the information returned by the show server real command.

TABLE 41 Real server information

Field Description

Server State Codes

State (St) The possible values for the server state. The state of each real server is shown by the State field, described in this table.

General Server Parameters

Name The name of the real server. This is the name you assigned to the server when you configured it on the Brocade Virtual ADX.


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TABLE 41 Real server information (Continued)

Field Description

State

Cost

Mac

Wt

SrcNAT

DestNAT

Serv-Rsts

Rx throughput

Tx throughput tcp conn rate udp conn rate

Use local conn

The state of the real server, based on Layer 3 health checks. The state can be one of the following states, also listed next to "Server State" at the top of the show server real display:

•

ACT: Active

•

ENB: Enabled

•

FAL: Failed

•

TST: Test

•

DIS: Disabled

•

UNK: Unknown

•

UNB: Unbind

•

AWU: Await-unbind

•

AWD: Await-delete

NOTE: HLD: Held-down. The value in this field is based on the results of

Layer 3 health checks, if enabled. The real server state can also be seen in the State column in the show server session display.

To display the server state based on Layer 3 health checks, refer to the State field in the show server session display.

The hop cost to reach the remote or cache server.

The real server MAC address or next hop MAC address for remote servers.

The weight assigned to this server. The weight applies only if the

predictor (load balancing method) is “weighted”. Refer to “Unbinding all application ports from virtual servers” on page 119.

The configured and operational states of the source NAT feature. The two states are separated by a colon (:). The configured state is shown first, followed by the operational state. Each state can have one of the following values:

•

0 – Disabled

•

1 – Enabled

The configured and operational states of the destination NAT feature.

The two states are separated by a colon (:). The configured state is shown first, followed by the operational state. Each state can have one of the following values:

•

0 – Disabled

•

1 – Enabled

Number of resets sent by the real server for a TCP SYN packet forwarded by Brocade Virtual ADX.

Rate at which packets are received expressed in Kbps.

Rate at which packets are transmitted expressed in Kbps.

Rate at which the server receives TCP connections.

Rate at which a real or remote server receives UDP connections.

Not currently supported/valid for Brocade Virtual ADX.


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Using the show server real detail command

Use the show server real detail command to view information not only about a specified real server, but also information about the various ports configured on that server.

Virtual ADX(config)#sh serv real rs1 detail

Real Servers Info

========================



HLD:held-down

Name: rs1 State: Enabled Cost: 0 IP:192.168.5.3: 1

Mac: Unknown Weight: 1/1 MaxConn: n/a

SrcNAT: not-cfg, not-op DstNAT: not-cfg, not-op Serv-Rsts: 0

Mem: Server: 2e09f26a Dynamic: No

Fail port exist: Y

Rx throughput: 804 Kbps Tx throughput: 1810 Kbps tcp conn rate:udp conn rate = 10:20

Use local conn : No


---- -- -- ------- ------- ------- ------- -------- -------- ---default UNB 0 0 0 0 0 0 0 0



:0

Rx throughput: 0 Kbps Tx throughput: 0 Kbps



Use local conn : No http ENB 0 0 500 2000 1000 300000 200000



SIP TCP Current Connections = 0

Rx throughput: 144 Kbps Tx throughput: 566 Kbps



Use local conn : No

Keepalive(G/L:On/Off):On

Table 42 describes the information returned by the show server real detail command. The fields

apply to all the TCP/UDP ports on the real servers.

For DNS, HTTP, and RADIUS ports, the server-specific health check information for the port is listed under the port’s statistics. For information about the health check parameters, refer to

“Changing

HTTP keepalive method, value, and status codes” on page 178.


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TABLE 42 Real server detail information

Field Description

Port

St

The TCP/UDP port name or number. This field can have one of the following values:

• default

• dns – The well-known name for port 53

• ftp – The well-known name for port 21. (Ports 20 and 21 both are

FTP ports but on the Brocade Virtual ADX, the name “ftp” corresponds to port 21.)

• http – The well-known name for port 80

• imap4 – The well-known name for port 143

• ldap – The well-known name for port 389

• nntp – The well-known name for port 119

• ntp – The well-known name for port 123

• pop2 – The well-known name for port 109


• radius – The well-known name for udp port 1812

• smtp – The well-known name for port 25

• snmp – The well-known name for port 161

• ssl – The well-known name for port 443

• telnet – The well-known name for port 23

• tftp – The well-known name for port 69

• number – The port number, if the port is not one of those listed above

The state of the port. The state can be one of the following:

• enabled

• failed

• test

• suspect

• graceful shutdown

• active

• unbnd

NOTE: If the state is unbnd, you have not bound the port to a virtual server port.


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TABLE 42 Real server detail information (Continued)

Field Description

Ms

CurConn

TotConns

Rx-pkts

Tx-pkts

Rx-octet

Tx-octet

Reas

The master port state. This field applies only to track ports and to ports to which you have bound other TCP/UDP ports in many-to-one configurations.

•

For track ports, the state of the master port. When a port is configured to track a master port, the Brocade Virtual ADX sends a client’s request for the tracking port to the same real server as the master port. Refer to

“Track port group function” on page 44. The

example show real server output shown above assumes that port

500 is tracked by port 600. If port 500’s state changes, port 600’s state also changes to match.

•

For many-to-one TCP/UDP port binding, the state of the port that is translated in the port binding between the real server and the virtual server. The ports that are not translated follow the state of

the port that is translated. Refer to “Multiple port binding” on page 69. In the example show real server output shown above,

assume that port 70 is untranslated and follows the state of port http. If the http port’s state changes, port 70’s state also changes to match.

This field can have one of the following values for the types of ports listed above:

•

1 – Enabled

•

2 – Failed

•

3 – Test

•

4 – Suspect

•

5 – Graceful shutdown

•

6 – Active

For all other types of ports, the value is always 0.

The number of client connections currently on the server. A connection consists of two sessions, the client-to-server session and the server-to-client session.

The number of client connections on the server since the Brocade

Virtual ADX was last booted. A connection consists of two sessions, the client-to-server session and the server-to-client session.

The number of packets the Brocade Virtual ADX has received from the server.

The number of packets the Brocade Virtual ADX has sent to the server.

The number of octets (bytes) the Brocade Virtual ADX has received from the server.

The number of octets (bytes) the Brocade Virtual ADX has sent to the server.

The number of times the Brocade Virtual ADX has reassigned the connection to another server in the rotation because the server that is in use has not responded to two contiguous TCP SYNs from the client.

When this occurs, the Brocade Virtual ADX directs the client to another server upon receiving the third SYN from the client.

NOTE: Windows 98 sends two TCP SYNs for each connection attempt.

NOTE: This statistic does not apply to Direct Server Return (Direct

Server Return).


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TABLE 42 Real server detail information (Continued)

Field Description

Rx throughput

Tx throughput

Rate at which packets are received expressed in Kbps.

Rate at which packets are transmitted expressed in Kbps.

Displaying real server keepalive statistics

Use the show server real keepalive command to view real server keepalive statistics:

Virtual ADX#show server real keepalive 8080 rs1

Port index 255

Real Server Name: rs1

Slot valid = TRUE real port proto = TCP

Keepalive Enabled

TCP request = 3518128

TCP response timeout = 19

HTTP URL = “GET/health.html”

HTTP sent = 318805

HTTP received error = 26394

HTTP wait for response = FALSE

Server close = 10

Bring port down = 9

TCP RTT = 14000 us

Next slot index = 193

Real Port Status = ACTIVE

IP: 135.200.41.63

Real port no = 8080

Keepalive port proto = TCP/8080

TCP response = 318805

Received ok = 292385

Received timeout = 0

Status Code = 200

Current sent = 0

Total retries = 14

Appl RTT = 3300 us

Syntax: show server real keepalive port | server-name

Displaying real server connections per second statistics

Use the show server connection command to view real server connections per second (CPS):

Virtual ADX#show server connection

Avail. Sessions on MP = 999888 Total Sessions on MP = 1000000 bp-1 Avail. Session = 1999868 Total Sessions = 2000000 bp-2 Avail. Session = 1999872 Total Sessions = 2000000 bp-3 Avail. Session = 1999872 Total Sessions = 2000000 bp-4 Avail. Session = 1999868 Total Sessions = 2000000

Total C->S Conn

Total Reassign

=

= last conn rate = last TCP attack rate =

97920 Total S->C Conn

0 Unsuccessful Conn

29 max conn rate

=

=

=

0 max TCP attack rate =

0

0

0

0

SYN def RST = 0 SYN flood = 0


Real Server State CurrConn TotConn CurrRate MaxRate rs1 r6

1

6

0

240

Syntax: show server connection

0

97920

0

30

0

40


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Use the show server virtual command to view information about the virtual servers configured on the Brocade Virtual ADX.

To display configuration information for a specific virtual server, enter the show server virtual command using its server name such as in the following example:

Virtual ADX(config)# show server virtual v6

Virtual Servers Info

Name: v6 State: Enabled IF DWN IP:400::456: 1

Pred: round-robin ACL-Id: 0 TotalConn: 0

VIP state: healthy

Rx pkts: 0 Tx pkts: 0

Rx bytes: 0 Tx bytes: 0

Rx PPS: 0 Tx PPS: 0

Rx Throughput: 0 Kbps Tx Throughput: 0 Kbps tcp-conn-rate: 0 udp-conn-rate: 0

CPS: 0 CurrConn: 0

Note: The above statistics lag by 1 second

Port State Sticky Concur Proxy DSR CurConn TotConn PeakConn

---- ----- ------ ------ ----- --- ------- ------- -------default enabled NO NO NO NO 0 0 0 http enabled NO NO NO NO 0 0 0

Port Rx-pkts Tx-pkts Rx-octet Tx-octet

---- ------- ------- -------- -------default 0 0 0 0 http 0 0 0 0

Syntax: show server virtual Virtual-server-name | Virtual-server-IP-address virtual-port

The Virtual-server-name variable specifies the virtual server by name. Alternatively, the

Virtual-server-IP-address variable can be used to specify the IP address of the virtual server. The virtual-port variable can be used to specify a particular port on the virtual server. For more

information, see “Displaying a list of failed servers” on page 380.

Table 43 describes the different types of information that can be viewed using the show virtual

server command:

TABLE 43 Virtual server information

Field Description

General Server Parameters

Name The name of the virtual server. This is the name you assigned to the server when you configured it on the Brocade Virtual ADX.

State

IP

The status of the virtual server. The status can be one of the following:

•

Enabled

•

Disabled

The IP address of the virtual server.

If you configured a host range of VIPs on the server, the number following the IP address

(after the colon) is the number of hosts on the server. In the example above, the VIP has a host range of 4 addresses.


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Rx Pkts

Rx bytes

Rx PPS

Rx throughput

Tx Pkts

Tx bytes

Tx PPS

Tx throughput tcp-conn-rate udp-conn-rate

CPS

CurrConn

TABLE 43 Virtual server information (Continued)

Field Description

ACL ID

Predictor

Tot-Conn

VIP state

Displays the ID of the Access Control List (ACL) policy bound to the virtual server

The load balancing predictor the Brocade Virtual ADX uses to balance traffic among the real servers bound to this virtual server. The predictor can be one of the following:

• least-conn

• round-robin

• weighted-round-robin

• weighted

• enhanced-weighted

You can assign these metrics on a global basis and an individual virtual server basis.

For more information, refer to

“Load-balancing predictor” on page 8.

To change the predictor (globally or locally), refer to “Changing the Load-Balancing

Predictor Method” on page 21.

The number of client connections on the server since the Brocade Virtual ADX was last booted or restarted. A connection consists of two sessions, the client-to-server session and the server-to-client session.

Displays the health of the virtual server. The health status can be one of the following:

•

Healthy — Indicates the virtual server is healthy.

•

Not healthy — Indicates the virtual server is not healthy.

Displays the total number of packets received by the virtual server.

Displays the total number of bytes received by the virtual server.

Displays the total number of packets per second received by the virtual server.

The rate of throughput received in Kbps.

Displays the total number of packets transmitted by the virtual server.

Displays the total number of bytes transmitted by the virtual server.

Displays the total number of packets per second transmitted by the virtual server.

The rate of throughput transmitted in Kbps.

The TCP connection rate.

The UDP connection rate.

The connection rate measured in seconds.

Displays the number of current open connections on the virtual server.


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Field Description

TCP/UDP Port Information and Statistics

Port

State

The TCP/UDP port name or number. This field can have one of the following values:

• default

• dns –The well-known name for port 53

• ftp – The well-known name for port 21. (Ports 20 and 21 both are FTP ports but on the Brocade Virtual ADX, the name “ftp” corresponds to port 21.)

• http – The well-known name for port 80

• imap4 – The well-known name for port 143

• ldap – The well-known name for port 389

• nntp – The well-known name for port 119

• ntp – The well-known name for port 123


• pop3 –The well-known name for port 110

• radius – The well-known name for udp port 1812

• radiuso – UDP port 1645, which is used in some older RADIUS implementations instead of port 1812

• smtp – The well-known name for port 25

• snmp – The well-known name for port 161

• ssl – The well-known name for port 443

• telnet – The well-known name for port 23

• tftp – The well-known name for port 69

• number – The port number, if the port is not one of those listed above

The state of the port. The state can be one of the following:

• enabled

• failed

• test

• suspect

• graceful shutdown

• active

• unbnd

NOTE: If the status is unbnd, you have not bound the port to a real server port.

Sticky

Concur

Proxy

CurConn

Whether the port is “sticky”. When a port is sticky, the Brocade Virtual ADX uses the same real server for multiple requests from the same client for the port. For non-sticky ports, the Brocade Virtual ADX load balances the requests and thus does not necessarily send them all to the same real server.

This parameter can have one of the following values:

•

NO

•

YES

Whether the port is configured for concurrent connections. A port configured to allow concurrent connections can have more than one connection open to the same client at the same time.

Displays the state of the proxy. The state can be one of the following:

•

No

•

Yes

Displays the state of the concurrent sessions that are additionally opened. The state can be one of the following:

•

No

•

Yes


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Displaying a list of failed servers


Field Description

DSR

TotConn

PeakConn

RX-pkts

Tx-pkts

Rx-octet

Tx-octet

Displays the state of the Direct Server Return (DSR) in the virtual server port. The state can be one of the following:

•

No

•

Yes

The number of client connections on the server since the Brocade Virtual ADX was booted. A connection consists of two sessions, the client-to-server session and the server-to-client session.

The highest number of connections the VIP has had at the same time.

Displays the number of packets the port as received from the server.

Displays the number of packets the port as transmitted from the server.

The number of octets (bytes) the port has received from the server.

The number of octets (bytes) the port has sent to the server.

Displaying a list of failed servers

Use show server failed to display all servers that are not in Active or Disabled state. Only servers in the failed state are included in the display.

Example

SLB-Virtual ADX#show server failed

Real servers in Failed state:

Total failed servers: 3

Name: MyServer01 IP:192.168.160.91 State: Enabled



Syntax: show server failed

Displaying a list of failed ports

Use show server port failed to display all server ports that are not in Active or Disabled state. It also shows the servers to which the ports belong.

Example

SLB-Virtual ADX#show server port failed

Real ports in Failed state:

Total failed servers:3 Total failed ports:7


Port http: Failed

Port 8081: Failed

Port ftp: Failed


Port 8082: Failed

Port http: Failed


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Displaying port-binding information

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Port 8083: Failed

Port http: Failed

Syntax: show server port failed


Using the “show server bind” command

To display port-binding information, enter the following command.

SLB-Virtual ADX#show server bind

http -------> s43: 10.157.23.43, http

s60: 10.157.23.60, 8080

ftp -------> s43: 10.157.23.43, ftp

s60: 10.157.23.60, ftp

70 -------> s43: 10.157.23.43, 70

s60: 10.157.23.60, 70

Virtual Server Name: v105, IP: 10.157.23.105

telnet -------> s60: 10.157.23.60, 300

ftp -------> s60: 10.157.23.60, 200

http -------> s60: 10.157.23.60, 100

dns -------> s60: 10.157.23.60, 400

tftp -------> s60: 10.157.23.60, 500

Syntax: show server bind

The display lists the port bindings for each virtual server configured on the Brocade Virtual ADX.

The first row of information for each virtual server lists the virtual server name and VIP. The following rows list the TCP/UDP ports configured on the virtual server and the real servers and port names or numbers to which each port is bound.

In the example, two virtual servers are configured on the Brocade Virtual ADX, v100 and v105. The first set of rows in the example output is for virtual server v100, with VIP 10.157.23.100.

The rows below the first row list the real servers and ports to which the virtual server’s ports are bound. The rows are grouped by port type. The first two rows after the first row in the example above list the port bindings for the virtual server’s HTTP port. In this case, the virtual server is bound to an HTTP port on two real servers, s43 and s60. The port name or number on the real server is listed after the real server’s IP address. In this example, the HTTP port to which v100 is bound on s43 is "http", which is the well-known name for the port. The virtual server’s HTTP port is bound to port 8080 on real server s60.

Using the “show server session” command

You can also display port-binding information by entering the show server session command.


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Virtual ADX1/1#show server session


Hash size = 200001



Server State - 0: diasbled, 1:enabled, 2:failed, 3:test, 4:suspect, 5:grace_dn,

6:active

Real Server St CurrConn TotConn TotRevConn CurrSess PeakConn rs1 1 0/0/0 0 0 0 0

Syntax: show server session

Table 44 lists the displayed information for bound ports.

TABLE 44 Field descriptions for the show server session command

Field Description

Global Statistics

Avail. Sessions

Total Sessions

Total C->S Conn

Total S->C Conn

Total Reassign

Unsuccessful Conn

Fast-aged: total

The number of sessions that are still available for use. By default, the

Brocade Virtual ADX is configured to allow the maximum number of sessions it can support. If you need to decrease the number of sessions

supported, refer to “Configuring the maximum number of active sessions” on page 236.

The number of sessions that are currently in use.

The number of connections initiated by clients.

The number of connections initiated by servers. Generally this value is 0 unless the client is using FTP or another application that causes the server to initiate connections.

The number of unacknowledged TCP SYN-ACKs on all the real servers combined. When a server reaches the maximum number of unacknowledged TCP SYN-ACKs allowed by the Brocade Virtual ADX (the reassign threshold), the Brocade Virtual ADX marks that server FAILED and removes it from the load balancing rotation.

The TCP SYN-ACK counter increments only when acknowledgments are not received. Each time an expected TCP SYN-ACK is received from a real server, the counter is cleared for that server, thus reducing the total count.

For more information, refer to “Reassign threshold” on page 220.

NOTE: This statistic does not apply to Direct Server Return (Direct

Server Return).

The number of connection attempts by clients or servers that were unsuccessful.

If the fast-age threshold is configured, the total number of sessions that were aged out because the number of free sessions dropped below the fast-age threshold, in addition to the number of these sessions that were aged out in the last 60 seconds.


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TABLE 44 Field descriptions for the show server session command (Continued)

Field Description

Random-aged: total If the random threshold is configured, the total number of sessions that were aged out at random because the number of free sessions dropped below the random threshold, in addition to the number of sessions that were aged out randomly in the last 60 seconds.

Refer to “Configuring fast session aging” on page 237 for more

information on the fast-age and random thresholds.

Statistics for Individual Real Servers

Server State

Real Server

St

CurConn

TotConn

Tot RevConn

CurrSess

PeakConn

The possible values for the server state. The state of each real server is shown by the State field.

The name of the real server. This is the name you gave the server when you configured it.

The state of the real server. The state can be one of the states listed by

"Server State" at the top of the display.

NOTE: The value in this field is based on the results of Layer 3 health checks. To display the server state based on Layer 4 or Layer 7 health checks, refer to the State field in the show server real display. (Refer to

“Displaying real server information and statistics” on page 371.)

The number of client connections currently on the server. A connection consists of two sessions, the client-to-server session and the server-to-client session.

The number of client connections on the server since the Brocade

Virtual ADX was last booted or restarted. A connection consists of two sessions, the client-to-server session and the server-to-client session.

The total number of connections initiated by the server to a client.

The number of sessions currently open on the Brocade Virtual ADX.

The highest number of simultaneous connections the Brocade Virtual

ADX has managed since it was last booted or restarted.


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Displaying packet traffic statistics


In theory, each BP sends its counters to the MP. The MP then aggregates all the counters from each

BP and synthesizes them into tables. However in reality, not all the BP counters are currently implemented on the MP.

The MP correctly shows most of the commonly used counters. For some counters, including show server traffic and show server debug, you should use the rconsole command in the BPs and issue show commands from there.

Use clear server traffic to clear traffic statistics for real and virtual servers.


Virtual ADX1/1#show server traffic

Client->Server = 0 Server->Client = 0

Drops = 0 Aged = 0

Fw_drops = 0 Rev_drops = 0

FIN_or_RST = 0 old-conn = 0

Disable_drop = 0 Exceed_drop = 0

Stale_drop = 0 Unsuccessful = 0

SYN def/proxy RST = 0 Server Resets = 0

Out of Memory = 0 Out of Memory = 0 last conn rate = 0 max conn rate = 0 last TCP attack rate = 0 max TCP attack rate = 0 fast vport found = 0 fast vport n found = 0

Fwd to non-static FI = 0 Dup stale SYN = 0

TCP forward FIN = 0 TCP reverse FIN = 0

Fast path FWD FIN = 0 Fast path REV FIN = 0

Fast path SLB SYN = 0 Dup SYN after FIN = 0

Duplicate SYN = 0 Duplicate sessions = 0

TCP ttl FIN recvd = 0 TCP ttl reset recvd = 0

Sessions in DEL_Q = 0 Sess force deleted = 0

Fwd sess not found = 0 sess already in delQ = 0

Sess rmvd from delQ = 0

Fragment buf full er = 0 Incoming TCP cksum e = 0

New sess sync sent = 0 New sess sync recvd = 0

L4 msg sent = 0 L4 msg recvd = 0 brocade packet sent = 0 ipc packet sent = 8

TCP SYN received = 0 TCP SYN dropped = 0

TCP SYN to MP = 0 TCP SYN ACK to MP = 0

TCP SYN ACK received = 0 TCP SYN ACK dropped = 0

TCP pkt received = 0 TCP pkt dropped = 0

TCP pkt to MP = 0

Syntax: show server traffic

Table 45 lists the displayed information for bound ports.

TABLE 45 Field descriptions for the show server traffic command

Field Description

Client->Server

Server->Client

Number of packets sent from clients to servers.

Number of packets sent from servers to clients.


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TABLE 45 Field descriptions for the show server traffic command (Continued)

Field Description

Drops

Aged

Fw_drops

Rev_drops

FIN_or_RST

Number of packets dropped by the Brocade Virtual ADX. This statistic includes the following:

•

TCP Resets – Resets sent by the Brocade Virtual ADX

•

Forward Resets – Resets from the client

•

Unsuccessful requests – Requests sent to a TCP or UDP port that is not bound to the request’s destination VIP

Number of TCP and UDP sessions that the Brocade Virtual ADX closed because they aged out. A session ages out when the age timer configured on the Brocade Virtual ADX expires. For more information, refer to

“Configuring TCP age” on page 239 and “Configuring UDP age” on page 239.

Number of client-to-server packets the Brocade Virtual ADX has dropped. If this statistic is high, there might not be a session entry. This scenario can occur under the following circumstances:

•

If the session is terminated normally but the client sends another

RESET.

•

If the maximum number of sessions has been reached.

•

If all the real servers are down.

Number of server-to-client packets the Brocade Virtual ADX has dropped. If this statistic is high, there might not be a session entry. This can occur for the same reasons as listed for the Fw_drops field.

Number of FINs or RSTs passing through (forward and reverse) a non-optimized path inside the Brocade Virtual ADX. All traffic is optimized by default except FTP control, streaming protocol control, and

DNS traffic.

old-conn fast vport found

Duplicate SYN

TCP ttl reset recvd

Disable_drop

Exceed_drop

Stale_drop

Number of successful virtual-port searches using an improved (faster) method.

When the Brocade Virtual ADX receives a SYN packet for a session that is already listed in the session table (show server sessions), the Brocade

Virtual ADX has received a Duplicate SYN. The counter is then incremented by 1.

Total (ttl) number of TCP resets received in both the forward and reverse direction. This counter applies to both optimized (FPGA assisted) and non optimized traffic paths.

Number of packets the Brocade Virtual ADX dropped because they were sent by a client to a VIP port that is bound to a real server port that is currently disabled.

Number of packets dropped by the Brocade Virtual ADX because the TCP

SYN limit on the real servers had been reached. The TCP SYN limit is a configurable parameter that allows you to protect servers against TCP

SYN attacks by limiting the number of TCP SYN requests the Brocade

Virtual ADX can send to the server each second.

For more information, refer to “Configuring the maximum number of active sessions” on page 236.

Number of TCP SYN packets the Brocade Virtual ADX dropped because they matched a stale session entry.


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Displaying configuration information

TABLE 45 Field descriptions for the show server traffic command (Continued)

Field Description

Unsuccessful last conn rate max conn rate last TCP attack rate max TCP attack rate

Number of packets that were dropped for one of the following reasons:

•

A deny filter configured on the Brocade Virtual ADX matched the packet, causing the Brocade Virtual ADX to drop the packet.

•

A client requested a TCP/UDP port that is not bound on the VIP.

Rate of TCP traffic per second. This counter includes all TCP traffic, including TCP SYN DoS attacks.

Peak rate of TCP traffic (per second) encountered on this device

Rate of TCP Dos attacks per second. This rate is delayed by 1 to 2 minutes. This field displays in releases 09.0.00S and later.

Peak rate of TCP DoS attacks (per second) encountered on this device.

This rate is delayed by 1 to 2 minutes.


This section contains the following sections:

•

“Showing aggregate health of tracked ports” on page 386

•

“Auto repeat of show command output” on page 387

•

“Clearing all session table entries” on page 387

•

“Clearing the connections counter” on page 388

Showing aggregate health of tracked ports

If a real server port goes down, none of the track port groups on the real server are considered for load balancing. To check the health of track-group state, use the following command.

Virtual ADX(config)#show track-group-state

This command displays the state of all configured track groups on the Brocade Virtual ADX, as shown in the following example.

Virtual ADX#show track-group-state

Virtual Server track-group state

v1 80 3030 21 SUSPECT

v2 443 80 UP

v3 80 443 SUSPECT

NOTE

The state can be either UP or SUSPECT, depending on the state of the real server ports that are bound to track-group ports. The track-group state is never in a DOWN state.


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Auto repeat of show command output

The repeat-show “cmd-to-show” interval command is a regular show command that is repeated at periodic intervals. You can issue this command from any mode (user, privileged, or configuration) from a Telnet session, SSH session, or a console.

To repeat the show command display at specific intervals, use the following command (on MP only).

Virtual ADX#repeat-show “show server session” 8

This example displays the results of a show server session command every 8 seconds.

Syntax: repeat-show “cmd-to-show” interval

The “cmd to show” variable is the actual command display to be shown repeatedly. The double quotes allow the command to accommodate white space.

The interval variable specifies the interval for repeated displays (range from 1 to 60 seconds).

To stop the repeat-show command in the current session, use the following command (on MP only).

Virtual ADX#stop-repeat-show

Syntax: stop-repeat-show

NOTE

The stop-repeat-show command stops all the repeat-show commands issued in the session.

The repeat-show commands are very similar to the traceroute and stop-traceroute commands.

When you end a Telnet session, this command cleans up the Telnet session and issues the stop-repeat-show command.

Clearing all session table entries

To clear all session table entries for a deleted real server, enter the clear server session command.

Syntax: clear server session name [ name [ name [ name ]]]

The name variable specifies the name of the real server. You can enter up to four real server names. It can take up to three minutes for the command to take effect. This command is supported only on the MP (the main processor management session).

When you delete a real server, the Brocade Virtual ADX attempts to clear all the session entries for that real server from the session table. The Brocade Virtual ADX requires all the sessions to be cleared from the table before performing these operations. If you use the force shutdown option

(server force-delete command), the Brocade Virtual ADX ends the sessions within one minute.

Otherwise, the Brocade Virtual ADX allows active sessions to end normally before removing them.

When you enter the command to delete a real server (no server real name ), the Brocade Virtual

ADX changes the server’s state to "await_delete". The real server remains in this state until all its sessions are cleared from the session table. Occasionally, the Brocade Virtual ADX cannot clear all of a deleted real server’s sessions from the table. When this occurs, to safely delete the real server from the Brocade Virtual ADX, Brocade recommends the following procedure.

1. Under the real server, disable the application ports.

2. Check to confirm that the current connections in the session come down to zero (in show server real output).


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3. Under VIP, unbind the real server.

4. Delete the real server.

To complete deletion of the server in this case, enter the clear server session name command after entering the no server real name command.

Example

Virtual ADX(config)#no server real rs1

Virtual ADX(config)#show server real rs1

Real Servers Info

Name : rs1 Mac-addr: Unknown

IP:10.2.3.4 Range:1 State:await_delete Max-conn: n/a

Least-con Wt:0 Resp-time Wt:0

Port State Ms CurConn TotConn Rx-pkts Tx-pkts Rx-octet Tx-octet Reas

---- ----- -- ------- ------- ------- ------- -------- -------- ----

8080 unbnd 0 0 0 0 0 0 0 0 default unbnd 0 0 0 0 0 0 0 0


Virtual ADX(config)#clear server session rs1

The no server real command deletes real server "rs1". The show server real command displays the states of the real servers. Notice that rs1 is still listed as a valid real server, and has the state

"await_delete". If the no server real command does not list the deleted server, the server has been completely deleted.

If the server continues to be listed with the "await_delete" state after several minutes, enter the clear server session command to finish deleting the server. The clear server session command deletes the remaining sessions for rs1, after which the Brocade Virtual ADX can finish deleting the server. You can enter this command immediately after entering the no server real command. You do not need to wait for any sessions to end normally.

NOTE

The clear server session real server command is used to clear sessions for a specific real server, regardless of the server in "await_del" or "await_u" state.

If you execute the clear server all-session real-server command from the MP, it clears all sessions in the MP and BP. If you use this command from the BP, it clears only the BP sessions.

The real-server variable is optional in the clear server all-session command and specifies the real server.

Clearing the connections counter

You can clear the counter for real servers only or virtual servers only.

To clear the total connections counter (“Tot-Conn”) in show commands for real and virtual servers, enter a command such as the following.

Virtual ADX(config-vs-Brocade)#clear server tot-conn virtual

Syntax: clear server tot-conn real | virtual


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Acknowledgements

Appendix

C

This appendix presents the acknowledgements for portions of code from various vendors that are included in the Brocade devices covered in this manual.

OpenSSL license

Copyright (c) 1998-2001 The OpenSSL Project. All rights reserved.

1. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

2. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

3. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation or other materials provided with the distribution.

4. All advertising materials mentioning features or use of this software must display the following acknowledgment: “This product includes software developed by the OpenSSL Project for use in the OpenSSL Toolkit. ( http://www.openssl.org/ )”

5. The names “OpenSSL Toolkit” and “OpenSSL Project” must not be used to endorse or promote products derived from this software without prior written permission. For written permission, please contact openssl-core@openssl.org

.

6. Products derived from this software may not be called “OpenSSL” nor may “OpenSSL” appear in their names without prior written permission of the OpenSSL Project.

7. Redistributions of any form whatsoever must retain the following acknowledgment: “This product includes software developed by the OpenSSL Project for use in the OpenSSL Toolkit

( http://www.openssl.org/ )”

THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT “AS IS'' AND ANY EXPRESSED OR

IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF

MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT

SHALL THE OpenSSL PROJECT OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,

INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED

TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR

BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY

WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH

DAMAGE.


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Cryptographic software

Cryptographic software

This product includes cryptographic software written by Eric Young ( eay@cryptsoft.com

). This product includes software written by Tim Hudson ( tjh@cryptsoft.com

).

Original SSLeay License

Copyright (C) 1995-1998 Eric Young ( eay@cryptsoft.com

)/. All rights reserved.

This package is an SSL implementation written by Eric Young ( eay@cryptsoft.com

). The implementation was written so as to conform with Netscape’s SSL.

This library is free for commercial and non-commercial use as long as the following conditions are adhered to. The following conditions apply to all code found in this distribution, be it the RC4, RSA, lhash, DES, etc., code; not just the SSL code. The SSL documentation included with this distribution is covered by the same copyright terms except that the holder is Tim Hudson

( tjh@cryptsoft.com

).

Copyright remains Eric Young's, and as such any Copyright notices in the code are not to be removed. If this package is used in a product, Eric Young should be given attribution as the author of the parts of the library used. This can be in the form of a textual message at program startup or in documentation (online or textual) provided with the package.

1. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

2. Redistributions of source code must retain the copyright notice, this list of conditions and the following disclaimer.

3. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation or other materials provided with the distribution.

4. All advertising materials mentioning features or use of this software must display the following acknowledgement:

“This product includes cryptographic software written by Eric Young ( eay@cryptsoft.com

)” The word 'cryptographic' can be left out if the routines from the library being used are not cryptographic related:-).

5. If you include any Windows specific code (or a derivative thereof) from the apps directory

(application code) you must include an acknowledgement:

“This product includes software written by Tim Hudson ( tjh@cryptsoft.com

)”

THIS SOFTWARE IS PROVIDED BY ERIC YOUNG “AS IS'' AND ANY EXPRESS OR IMPLIED

WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY

AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR

OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE

GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER

CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS

SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.


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The license and distribution terms for any publicly available version or derivative of this code cannot be changed. i.e. this code cannot simply be copied and put under another distribution license [including the GNU Public License.]


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