Classification Based On Class Maps And Policy Maps - Cisco IE 3000 Software Configuration Manual

Chapter 32 Configuring QoS
Understanding QoS
After a traffic class has been defined with the ACL, you can attach a policy to it. A policy might contain
multiple classes with actions specified for each one of them. A policy might include commands to
classify the class as a particular aggregate (for example, assign a DSCP) or rate-limit the class. This
policy is then attached to a particular port on which it becomes effective.
You implement IP ACLs to classify IP traffic by using the access-list global configuration command;
you implement Layer 2 MAC ACLs to classify non-IP traffic by using the mac access-list extended
global configuration command. For configuration information, see the "Configuring a QoS Policy"
section on page 32-38.

Classification Based on Class Maps and Policy Maps

A class map is a mechanism that you use to name a specific traffic flow (or class) and to isolate it from
all other traffic. The class map defines the criteria used to match against a specific traffic flow to further
classify it. The criteria can include matching the access group defined by the ACL or matching a specific
list of DSCP or IP precedence values. If you have more than one type of traffic that you want to classify,
you can create another class map and use a different name. After a packet is matched against the
class-map criteria, you further classify it through the use of a policy map.
A policy map specifies which traffic class to act on. Actions can include trusting the CoS, DSCP, or IP
precedence values in the traffic class; setting a specific DSCP or IP precedence value in the traffic class;
or specifying the traffic bandwidth limitations and the action to take when the traffic is out of profile.
Before a policy map can be effective, you must attach it to a port.
You create a class map by using the class-map global configuration command or the class policy-map
configuration command. You should use the class-map command when the map is shared among many
ports. When you enter the class-map command, the switch enters the class-map configuration mode. In
this mode, you define the match criterion for the traffic by using the match class-map configuration
command.
You create and name a policy map by using the policy-map global configuration command. When you
enter this command, the switch enters the policy-map configuration mode. In this mode, you specify the
actions to take on a specific traffic class by using the class, trust, or set policy-map configuration and
policy-map class configuration commands.
The policy map can contain the police and police aggregate policy-map class configuration commands,
which define the policer, the bandwidth limitations of the traffic, and the action to take if the limits are
exceeded.
To enable the policy map, you attach it to a port by using the service-policy interface configuration
command.
For more information, see the "Policing and Marking" section on page 32-8. For configuration
information, see the "Configuring a QoS Policy" section on page 32-38.
Cisco IE 3000 Switch Software Configuration Guide
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