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Catalyst 2960 Switch Software Configuration Guide
OL-8603-04
Chapter 28 Configuring QoS
Configuring Standard QoS
Classifying, Policing, and Marking Traffic on Physical Ports by Using Policy Maps
You can configure a policy map on a physical port that 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; and specifying the traffic bandwidth limitations for each
matched traffic class (policer) and the action to take when the traffic is out of profile (marking).
A policy map also has these characteristics:
• A policy map can contain multiple class statements, each with different match criteria and policers.
• A separate policy-map class can exist for each type of traffic received through a port.
• A policy-map trust state and a port trust state are mutually exclusive, and whichever is configured
last takes affect.
Follow these guidelines when configuring policy maps on physical ports:
• You can attach only one policy map per ingress port.
• If you configure the IP-precedence-to-DSCP map by using the mls qos map ip-prec-dscp
dscp1...dscp8 global configuration command, the settings only affect packets on ingress interfaces
that are configured to trust the IP precedence value. In a policy map, if you set the packet IP
precedence value to a new value by using the set ip precedence new-precedence policy-map class
configuration command, the egress DSCP value is not affected by the IP-precedence-to-DSCP map.
If you want the egress DSCP value to be different than the ingress value, use the set dscp new-dscp
policy-map class configuration command.
• If you enter or have used the set ip dscp command, the switch changes this command to set dscp in
its configuration.
• In Cisco IOS Release 12.2(25)SED or later, you can use the set ip precedence or the set precedence
policy-map class configuration command to change the packet IP precedence value. This setting
appears as set ip precedence in the switch configuration.
• Beginning with Cisco IOS Release 12.2(40)SE, a policy-map and a port trust state can both run on a
physical interface. The policy-map is applied before the port trust state.
Beginning in privileged EXEC mode, follow these steps to create a policy map:
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
class-map [match-all | match-any]
class-map-name
Create a class map, and enter class-map configuration mode.
By default, no class maps are defined.
• (Optional) Use the match-all keyword to perform a logical-AND
of all matching statements under this class map. All match criteria
in the class map must be matched.
• (Optional) Use the match-any keyword to perform a logical-OR of
all matching statements under this class map. One or more match
criteria must be matched.
• For class-map-name, specify the name of the class map.
If neither the match-all or match-any keyword is specified, the default
is match-all.
Note Because only one match command per class map is supported,
the match-all and match-any keywords function the same.
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