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z/VM
Module 11: Networking
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Objectives
 Describe TCP/IP setup in conjunction with z/VM
 Understand the fundamental concepts of computer networks
 List and describe the four different protocols of the TCP/IP
architecture and their purpose
 Describe the purpose and function of routing
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Objectives continued
 List the reasons for using a routing table and the major differences
between these dynamic routing table formats:
RIP-1
 RIP-2
 OSPF

 List and describe the four different types of internet addressing:
Network address format
 Broadcast address format
 Multicast address format
 Subnetwork address format

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Objectives continued
 Explain the major differences between the fiber connectors ESCON
and FICON
 Show and describe how a Parallel Sysplex is set up and the
enhancements it can provide
 Describe the devices and protocols that are available when
configuring your network, including:

QDIO (can be configured into guest LANs with z/VM 4.3)

OSA-Express and OSA-2

HiperSockets (can be configured into guest LANs)
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Objectives continued
 Describe how VIPA is capable of adding another level of
protection against network failures, along with recovery
 Discuss the four major commands needed to monitor your
TCP/IP network:

NETSTAT

RPCINFO

PING

TRACERTE
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z/VM and TCP/IP
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Computer Network
 Is a group of connected nodes that are used for data communication
 Its configuration consists of data processing devices, software, and
transmission media that are linked for information interchange
 Nodes are the functional units, located at the points of connection
among the data circuits
 Some of the more common network architectures, or protocols, used
today are OSI, TCP/IP, SNA, and ISDN.
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Internet Addressing
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OSI Model
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Internet Environment
 The internet is a logical collection of networks supported by:

Gateways

Routers

Bridges

Hosts

Various layers of protocols
 Protocols specify a set of rules and formats required to exchange and
transfer packets of information.
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Internet Environment continued
 Internet – a worldwide network of computer networks
 Intranet – a private network, usually used within a closed
environment supporting one company
 Extranet – a private network that uses the Internet protocols
and the public telecommunication system to share part of a
company’s business information with outside vendors
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TCP/IP Architecture
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TCP/IP Architecture continued
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Routing: Overview
 It is the method by which a host or a gateway decides where to send
a datagram.
 There are two kinds of routing that are involved in communication
within an internet:

Direct routing is used when the source and destination nodes are in the
same logical network within an internet.

Indirect routing is used when the source and destination nodes are on
different networks within an internet, where source nodes send packets
to a gateway or router on the same network using direct routing and the
packets are forwarded through intermediate gateways until the
destination is reached
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Routing: Overview - Terms
 Important terms are:

Router

Gateway

Daemon

Network Interface

Network

Subnetwork

FTP

TELNET
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Routing Tables
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Routing Table Management
 The most complex task in configuring the TCP/IP network routing is
establishing the routing tables.
 Static routing requires you to manually configure the routing tables
yourself.
 With dynamic routing, information is automatically exchanged among
various routers in your network, which allows IP address to be found
when a new IP host come online.
 The more common interior gateway protocols in dynamic routing are:


RIP-1
RIP-2
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Dynamic Routing: RIP Version 1
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Dynamic Routing: RIP Version 2
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OSPF
 Open Shortest Path First
 OSPF differs from RIP in these ways:

No limitations on the hop count

Intelligent use of VLSM

Uses IP multicast to send link-state updates

Better convergence

Better load balancing

Allows for routing authentication
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BGP
 Border Gateway Protocol is an interautonomous system routing
protocol.
 The attributes that BGP uses in the route selection process include:

Weight

Local preference

Multi-exit discriminator

Origin

AS_Path

Next hop

Community
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Virtual IP Addressing (VIPA)
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Internet Addressing and Network Address Format
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Internet Addressing: Broadcast, Multicast, and Subnetwork
 TCP/IP uses IP broadcasting to
send datagrams to all the TCP/IP
host on a network or subnetwork
 Multicasting also sends datagrams,
but you will only receive the
datagrams if the host is signed up to
listen for the particular IP multicast
address; otherwise it is discarded
 The subnetwork capability of
TCP/IP divides a single network into
multiple logical networks
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Networking Device Options
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ESCON
(Enterprise System Connectivity)
 The high-speed fiber optic architecture first available on
ES/9000 and many other peripherals
 Originally used LEDs and worked at 10MBps over 3 km
stretches
 A laser version announced in 1991 is capable of working at
greater distances
 Was replaced by FICON in 1998, though still available
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FICON (Fibre Connections)
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FICON CTC
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Parallel Sysplex Cluster Technology
 The zSeries Parallel Sysplex cluster contains innovative multi-system
data sharing technology.
 This allows direct, concurrent read/write access to shared data from
all processing modes in the configuration without sacrificing
performance or data integrity.
 The Parallel Sysplex manages this multi-system environment,
providing these benefits:

Continuous availability

Dynamic workload balancing

Application compatibility
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Parallel Sysplex Cluster Technology continued
 Within a Parallel Sysplex cluster it is possible to construct a parallel
processing environment with no single point of failure.
 The features of the Parallel Sysplex solution that contribute to
increased availability and also help eliminate some system
management tasks are:

Workload manager

Sysplex failure manager

Automatic restart manager

Cloning
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Queued Direct I/O (QDIO)
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Open System Adapters
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OSA-2
 An integrated hardware feature that allows a zSeries 900 to
provide industry-standard connectivity directly to clients on
local area networks.
 The clients on the attached LAN can use the TCP/IP or the
SNA/APPN protocol, or both.
 Ethernet, Fast Ethernet, and ATM LAN attachment to the z900
is supported by OSA-Express, but not by OSA-2.
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OSA-Express Characteristics
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Virtual IP Addressing
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What Are HiperSockets and What Benefits Do They Provide?
 They provide very fast TCP/IP communications between servers
running in different LPARs on a zSeries CEC.
 HiperSockets uses internal Queued Input/Output (iQDIO) at memory
speeds to pass traffic between the virtual servers.
 Important aspects of HiperSockets include:
 They can be used to communicate among consolidated servers
in a single processor

They can be customized to accommodate varying traffic sizes

Since there is no server-to-service traffic outside the zSeries
CEC, they provide a much higher level of network availability,
security, simplicity, performance, and cost effectiveness
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How Do HiperSockets Work?
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HiperSockets Usage Example
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HiperSockets Microcode Functions
 HiperSockets implementation is based on the OSA-Express QDIO
protocol, hence HiperSockets is also called internal iQDIO.
 TCP/IP stacks are addressed by inbound data queue addresses
instead of MAC addresses.
 The microcode maintains a lookup table of IP addresses for each
HiperSockets.
 The controlling operating system that performs I/O processing is
identical to OSA-Express in QDIO mode.
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z/VM Before Guest LANs
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z/VM Guest LAN
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z/VM’s Virtual Switch
 z./VM Virtual Switch is an extension of the Guest LAN
simulated networking function.
 VSWITCH operates almost exactly the same as a z/VM 4.3
QDIO Guest LAN, with two important exceptions:

Direct external network access via OSA Express

IEEE 802.1Q VLAN Support
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Network Consolidation Using the Virtual Switch
 A Virtual Switch is capable of bridging a z/VM Guest LAN to an
associated real LAN connected by an OSA-Express adapter.
 Virtual Switch operates as part of the z/VM CP and is not a
separate guest machine.
 Virtual Switch support is also used to manage the z/VM VLAN
environment.
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The Overall TCP/IP Setup
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Monitoring the TCP/IP Network - NETSTAT
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Monitoring the TCP/IP Network – NETSTAT continued
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Monitoring the TCP/IP Network – NETSTAT continued
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Monitoring the TCP/IP Network – NETSTAT continued
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NETSTAT Examples
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RPCINFO Command
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PING Command
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TRACERTE Command
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TRACERTE Command
Usage Notes
 To use the TRACERTE command, you must be a privileged TCP/IP
user.
 The range of port numbers that the TRACERTE command uses is
normally invalid; however you can change the starting port number
for this range if the target host is using a nonstandard UPD port.
 The TRACERTE function will give unpredictable results if the TCP/IP
stack is configured to use equal-cost multi-path support.
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Conclusion
 Important topics discussed in this
module:
TCP/IP
Protocols and Functions
– Link Protocols
– Networking Protocols
– Transport Protocols
– Application Protocols
Routing capabilities
Internet Addressing
– Networking address format
– Broadcast address format
– Multicast address format
– Subnetwork address format
 Important devices discussed in this
module:
ESCON
FICON
and FICON CTC
Parallel Sysplex
Queued Direct I/O
OSA-Express and OSA-2
Virtual IP Addressing
HiperSockets
Guest LANs
 Commands that are used to monitor
the networking devices are:
NETSTAT
RPCINFO
PING
TRACERTE
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Glossary
Channel-to-channel Adapter (CTCA) – an adapter that cross-connect
a pair of channels between systems to allow for point-to-point
communications between two systems.
Domain Name Server (DNS) -- the distributed data system (directory)
used to map domain names to IP addresses.
ESCON – Enterprise System Connection; a set of IBM products and
services that provide a dynamically connected environment within an
enterprise based upon fiber connections.
FICON – Fiber Connectivity; a high-speed I/O interface for mainframe
computer connections to storage devices. This new architecture is
about eight times as efficient as ESCON.
File Transfer Protocol (FTP): -- generally used for file transfers from
TCP/IP systems, it originated on the internet.
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Glossary
Network File System (NFS): – a set of UNIX protocols for file sharing
across a LAN; built on top of Ethernet and TCP/IP. Has became a
standard in the UNIX environment.
NFS Client – New to z/VM, NFS Client is integrated into both CMS and
the priced, optional TCP/IP feature of z/VM.
Socket – an end point provided by the transport service of a network
for communications between processes or application programs.
Secure Socket Layer (SSL): – a security protocol that provides
communication privacy; SSL enables client/server applications to
communicate in a way that is designed to prevent eavesdropping,
tampering, and message forgery.
Virtual Private Network (VPN): – a network comprised of one or more
secure IP tunnels connecting two or more networks.
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References
 IBM eserver zSeries 900: OSA-Express Overview. October
2001.
 TCP/IP Solutions for VM/ESA. 1999.
 White, Bill, Rama Ayyar, and Velibor Uskokovic. IBM Redbook:
zSeries HiperSockets. May 2002
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