Use the MQC to enable packet classification based on Layer 3 packet length. The MQC is a CLI that allows you to create traffic
policies, enable a QoS feature (such as packet classification), and attach these policies to interfaces.
In the MQC, the class-map command is used to define a traffic class (which is then associated with a traffic policy). The purpose of a traffic class
is to classify traffic.
The MQC consists of the following three processes:
Defining a traffic class with the class-map command.
Creating a traffic policy by associating the traffic class with one or more QoS features (using the policy-map command).
Attaching the traffic policy to the interface with the service-policy command.
A traffic class contains three major elements: a name, a series of match commands, and, if more than one match command exists in the traffic class, an instruction on how to evaluate these match commands. The traffic class is named in the class-map command line; for example, if you enter the class-map cisco command while configuring the traffic class in the CLI, the traffic class would be named "cisco".
The match commands are used to specify various criteria for classifying packets. Packets are checked to determine whether they match
the criteria specified in the match commands. If a packet matches the specified criteria, that packet is considered a member of the class and is forwarded according
to the QoS specifications set in the traffic policy. Packets that fail to meet any of the matching criteria are classified
as members of the default traffic class.