Cisco Catalyst QoS: Quality of Service in Campus Networks

124 Chapter 5: Introduction to the Modular QoS Command-Line Interface

The simplicity of configuration is made possible through the use of a common configu-

ration structure for all QoS components within the MQC. That is, the basic configuration

steps for configuring all QoS mechanisms is the same, with only small variations in the

configuration that are specific to the actual mechanism. You can configure all the mecha-

nisms through a three-step process:

Step 1 Class map configuration

Step 2 Policy map configuration

Step 3 Service policy application

This chapter describes each step in the configuration process, as well as the configuration

options, and also provides examples of MQC commands.

Step 1: The Class Map

The first step for configuring any QoS mechanism in the MQC is the configuration of a

class-map. Simply stated, the class map defines which traffic you want the router to match.

This is the fundamental step that allows the router to differentiate one traffic type from

another. This is traffic classification, and without classification there can be no QoS.

To differentiate traffic, it is possible to match on one traffic characteristic or multiple

characteristics. If you need to differentiate between traffic from 10.1.1.1 and traffic from

10.1.1.2, for example, the source IP address is the only characteristic that you need to

configure. If you have multiple traffic streams from 10.1.1.1 and need to differentiate

between those, however, as well as differentiate between multiple streams from 10.1.1.2,

you probably need to classify traffic based on multiple criteria, such as TCP or UDP port.

A possible scenario in which this would come into play might be server 10.1.1.1 that serves

production HTTP and FTP to the Accounting department, and server 10.1.1.2 that serves

nonproduction HTTP and FTP to the IT group that develops applications for the

Accounting department. Understanding that production traffic is the top priority, the devel-

opment group needs their traffic to have a minimum bandwidth guarantee to enable that

group to properly test a new HTTP application before delivering it to the Accounting

department for production use. This means that there will be QoS requirements for all

traffic from 10.1.1.1 and some traffic from 10.1.1.2. As such, just matching by IP address

does not suffice. In this case, there is a requirement to match on multiple characteristics.

Configuring the Class Map

When matching on multiple characteristics, two options exist for creating the class map:

match-any and match-all, as demonstrated in Example 5-1.

Example 5-1 Class Map Options

R1(config)# class-map ?

WORD class-map name

match-all Logical-AND all matching statements under this classmap

match-any Logical-OR all matching statements under this classmap