6.2.b Implement optimize and troubleshoot QoS using MQC

6.2.b [i] Classification

Packet classification involves using a traffic descriptor to categorize a packet within a specific group and making the packet accessible for QoS handling in the network. Using packet classification, you can partition network traffic into multiple priority levels or a class of service (CoS). You can use either access lists (ACLs) or the match command in the modular QoS CLI to match on DSCP values.

Adam, Paul (2014-07-12). All-in-One CCIE V5 Written Exam Guide (Kindle Locations 5634-5637).  . Kindle Edition.

http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/qos_classn/configuration/15-mt/qos-classn-15-mt-book/qos-classn-oview.html