3.4: Using MQC for Implementing QoS

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3.4: Using MQC for Implementing QoS


Objectives 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)


Methods for Implementing QoS PolicyMethod Description

Legacy CLI – Coded at the CLI– Requires each interface to be individually

configured– Time-consuming

MQC – Coded at the CLI– Uses configuration modules– Best method for QoS fine tuning

Cisco AutoQoS – Applies a possible QoS configuration to the interfaces

– Fastest way to implement QoS

Cisco SDM QoS wizard – Application for simple QoS configurations


Configuring QoS at the CLI 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


Guidelines for Using the CLI Configuration Method

Build a traffic policy:Identify the traffic pattern.Classify the traffic.Prioritize the traffic.Select a proper QoS mechanism:

QueuingCompression

Apply the traffic policy to the interface.


Legacy CLI QoS Example

For interactive traffic, you can use CQ and TCP header compression.

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


Modular QoS CLI 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


Modular QoS CLI Components


Step 1: Creating Class Maps:“What Traffic Do We Care About?”

Each class is identified using a class map.

A traffic class contains three major elements:A case-sensitive nameA series of match commandsAn 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.


Configuring Class Maps Enter class-map configuration mode. Specify the matching strategy.

class-map [match-all | match-any] class-map-namerouter(config)#

description descriptionrouter(config-cmap)#

Use at least one condition to match packets.

Use descriptions in large and complex configurations. The description has no operational meaning.

match anyrouter(config-cmap)#

match not match-criteria


Classifying Traffic with ACLs Standard ACL

access-list access-list-number {permit | deny | remark} source [mask]

router(config)#

access-list access-list-number {permit | deny} protocol source source-wildcard [operator port] destination destination-wildcard [operator port] [established] [log]

router(config)#

match access-group access-list-numberrouter(config-cmap)#

Extended ACL

Use an ACL as a match criterion


Step 2: Policy Maps: “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 nameA traffic classThe 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.


Configuring Policy Maps Enter policy-map configuration mode. Policy maps are identified by a

case-sensitive name.

policy-map policy-map-namerouter(config)#

class {class-name | class-default}router(config-pmap)#

class class-name conditionrouter(config-pmap)#

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.

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.


Step 3: Attaching Service Policies: “Where Will This Policy Be Implemented?”

Attach the specified service policy map to the input or output interface

service-policy {input | output} policy-map-namerouter(config-if)#

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


Modular QoS CLI Configuration Example

router(config)# class-map match-any business-critical-trafficrouter(config-cmap)# match protocol http url “*customer*”router(config-cmap)# match protocol http url citrix

router(config)# policy-map myqos policyrouter(config-pm am)# class business-critical-trafficrouter(config-pm am-c)# bandwidth 1000

router(config)# interface serial 0/0router(config-if)# service-policy output myqos policy

1

2

3


Boolean Nesting

Salaries

HockeyPlayers

FootballPlayers

Goal: Find books that cover the salaries of either football players or hockey players.

Solution: Boolean (salaries AND [football players OR hockey players]).

Goal


MQC Example

Voice traffic needs priority, low delay, and constant bandwidth.

Interactive traffic needs bandwidth and low delay.


MQC Configuration

hostname Office!class-map VoIP match access-group 100class-map Application match access-group 101!policy-map QoS-Policy class VoIP priority 100 class Application bandwidth 25 class class-default fair-queue!interface Serial0/0 service-policy output QoS-Policy!access-list 100 permit ip any any precedence 5access-list 100 permit ip any any dscp efaccess-list 101 permit tcp any host 10.1.10.20access-list 101 permit tcp any host 10.1.10.40

Classification

QoS Policy

QoS Policy on Interface

Classification


Basic Verification Commands

Display the class maps

show class-maprouter#

show policy-maprouter#

show policy-map interface type numberrouter#

Display the policy maps

Display the applied policy map on the interface


Summary 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?


Self Check1. 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?

3.4: Using MQC for Implementing QoS

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