Exam 642-642 Topic 1 Question 5 Discussion

The simplicity of configuration is made possible through the use of a common configuration 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 mechanisms through a three-step process: Step 1. Class map configuration Step 2. Policy map configuration Step 3. Service policy application
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 development 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.
Example of Creating class-map
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