Module 3: Introduction to IP QoS
© 2006 Cisco Systems, Inc. All rights reserved.

© 2006 Cisco Systems, Inc. All rights reserved.

 Identify the features of each method for QoS policy implementation.
 Describe the guidelines for using CLI to implement QoS policy.
 Describe the Modular QoS Command Line (MQC)
© 2006 Cisco Systems, Inc. All rights reserved.

Method
Legacy CLI
MQC
Cisco AutoQoS
Description
– Coded at the CLI
– Requires each interface to be individually configured
– Time-consuming
– Coded at the CLI
– Uses configuration modules
– Best method for QoS fine tuning
– Applies a possible QoS configuration to the interfaces
– Fastest way to implement QoS
Cisco SDM QoS wizard – Application for simple QoS configurations
© 2006 Cisco Systems, Inc. All rights reserved.

 Uses the CLI via console and Telnet
 Traditional method
 Nonmodular
 Cannot separate traffic classification from policy definitions
 Time-consuming and potentially error-prone task
 Used to augment and fine-tune newer Cisco AutoQoS method
© 2006 Cisco Systems, Inc. All rights reserved.

 Build a traffic policy:
Identify the traffic pattern.
Classify the traffic.
Prioritize the traffic.
Select a proper QoS mechanism:
Queuing
Compression
 Apply the traffic policy to the interface.
© 2006 Cisco Systems, Inc. All rights reserved.

 interface multilink
 ip address 10.1.61.1 255.255.255.0
 load-interval 30
 custom-queue-list 1
 ppp multilink
 ppp multilink fragment-delay 10
 ppp multilink interleave
 multilink-group 1
 ip tcp header-compression iphc-format
 !
 queue-list 1 protocol ip 2 tcp 23
 For interactive traffic, you can use CQ and TCP header compression.
© 2006 Cisco Systems, Inc. All rights reserved.

 A command syntax for configuring QoS policy
 Reduces configuration steps and time
 Configures policy, not “raw” per-interface commands
 Uniform CLI across major Cisco IOS platforms
 Uniform CLI structure for all QoS features
 Separates classification engine from the policy
© 2006 Cisco Systems, Inc. All rights reserved.

© 2006 Cisco Systems, Inc. All rights reserved.

“What Traffic Do We Care About?”
 Each class is identified using a class map.
 A traffic class contains three major elements:
A case-sensitive name
A series of match commands
An instruction on how to evaluate the match commands if more than one match command exists in the traffic class
 Class maps can operate in two modes:
Match all: All conditions have to succeed.
Match any: At least one condition must succeed.
 The default mode is match all.
© 2006 Cisco Systems, Inc. All rights reserved.

 Enter class-map configuration mode. Specify the matching strategy.
router(config)# class-map [match-all | match-any] class-map-name
 Use at least one condition to match packets.
router(config-cmap)# match any match not match-criteria
 Use descriptions in large and complex configurations. The description has no operational meaning.
router(config-cmap)# description description
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 Standard ACL router(config)# access-list access-list-number {permit | deny | remark}
source [mask]
 Extended ACL router(config)# access-list access-list-number {permit | deny} protocol
source source-wildcard [operator port] destination
destination-wildcard [operator port] [established] [log]
 Use an ACL as a match criterion router(config-cmap)# match access-group access-list-number
© 2006 Cisco Systems, Inc. All rights reserved.

“What Will Be Done to This Traffic?”
 A policy map defines a traffic policy, which configures the QoS features associated with a traffic class that was previously identified using a class map.
 A traffic policy contains three major elements:
A case-sensitive name
A traffic class
The QoS policy that is associated with that traffic class
 Up to 256 traffic classes can be associated with a single traffic policy.
 Multiple policy maps can be nested to influence the sequence of QoS actions.
© 2006 Cisco Systems, Inc. All rights reserved.

 Enter policy-map configuration mode. Policy maps are identified by a case-sensitive name.
router(config)# policy-map policy-map-name
 Enter the per-class policy configuration mode by using the name of a previously configured class map. Use the class-default name to configure the policy for the default class.
router(config-pmap)# class {class-name | class-default}
 Optionally, you can define a new class map by entering the condition after the name of the new class map. Uses the match-any strategy.
router(config-pmap)# class class-name condition
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“Where Will This Policy Be Implemented?”
 Attach the specified service policy map to the input or output interface router(config-if)# service-policy {input | output} policy-map-name class-map HTTP match protocol http
!
policy-map PM class HTTP bandwidth 2000 class class-default bandwidth 6000
!
interface Serial0/0 service-policy output PM
Service policies can be applied to an interface for inbound or outbound packets
© 2006 Cisco Systems, Inc. All rights reserved.

1 router(config)# class-map match-any business-critical-traffic router(config-cmap)# match protocol http url “*customer*” router(config-cmap)# match protocol http url citrix
2 router(config)# policy-map myqos policy router(config-pm am)# class business-critical-traffic router(config-pm am-c)# bandwidth 1000
3 router(config)# interface serial 0/0 router(config-if)# service-policy output myqos policy
© 2006 Cisco Systems, Inc. All rights reserved.

Goal
Salaries
Football
Players
Hockey
Players
Goal: Find books that cover the salaries of either football players or hockey players.
Solution: Boolean (salaries AND [football players OR hockey players]).
© 2006 Cisco Systems, Inc. All rights reserved.

 Voice traffic needs priority, low delay, and constant bandwidth.
 Interactive traffic needs bandwidth and low delay.
© 2006 Cisco Systems, Inc. All rights reserved.

hostname Office
!
class-map VoIP match access-group 100 class-map Application match access-group 101
!
policy-map QoS-Policy
Classification class VoIP priority 100 class Application bandwidth 25 class class-default fair-queue
QoS Policy
!
interface Serial0/0 service-policy output QoS-Policy
QoS Policy on Interface
!
access-list 100 permit ip any any precedence 5 access-list 100 permit ip any any dscp ef access-list 101 permit tcp any host 10.1.10.20
access-list 101 permit tcp any host 10.1.10.40
Classification
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 Display the class maps router# show class-map
 Display the policy maps router# show policy-map
 Display the applied policy map on the interface router# show policy-map interface type number
© 2006 Cisco Systems, Inc. All rights reserved.

 There are 4 basic ways to implement QoS policy on Cisco devices:
CLI, MQC, AutoQoS and SDM. Choosing a method will depend on the complexity of the network on the expertise of the administrator.
 The Cisco MQC offers significant advantages over the legacy CLI method for implementing QoS. By using MQC, a network administrator can significantly reduce the time and effort it takes to configure QoS in a complex network.
 There are three steps to follow when configuring QoS using Cisco
MQC configuration. Each step answers a question concerning the classes assigned to different traffic flows:
What traffic do we care about?
What will happen to the classified traffic?
Where will the policy apply?
© 2006 Cisco Systems, Inc. All rights reserved.

1.
What is a class map?
2.
How many class maps can be configured on a Cisco router?
3.
What is a traffic policy?
4.
What are the 3 basic elements of a traffic policy?
5.
What command is used to assign a policy map to an interface?
© 2006 Cisco Systems, Inc. All rights reserved.

© 2006 Cisco Systems, Inc. All rights reserved.

 Modular Quality of Service Command-Line Interface http://www.cisco.com/en/US/partner/products/sw/iosswrel/ps501
4/products_feature_guide_book09186a0080088141.html
 QoS Policing: Cisco Modular Quality of Service
Command Line Interface http://www.cisco.com/en/US/partner/tech/tk543/tk545/technologi es_white_paper09186a0080123415.shtml
© 2006 Cisco Systems, Inc. All rights reserved.

© 2006 Cisco Systems, Inc. All rights reserved.