Cisco Catalyst 3750-E Software Configuration Manual page 913

Chapter 37 Configuring QoS
A policy map also has these characteristics:
A policy map can contain multiple class statements, each with different match criteria and policers.
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A policy map can contain a pre-defined default traffic class explicitly placed at the end of the map.
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A separate policy-map class can exist for each type of traffic received through a port.
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Follow these guidelines when configuring policy maps on physical ports:
You can attach only one policy map per ingress port.
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If you configure the IP-precedence-to-DSCP map by using the mls qos map ip-prec-dscp
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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
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its configuration.
You can use the set ip precedence or the set precedence policy-map class configuration command
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to change the packet IP precedence value. This setting appears as set ip precedence in the switch
configuration.
You can configure a separate second-level policy map for each class defined for the port. The
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second-level policy map specifies the police action to take for each traffic class. For information on
configuring a hierarchical policy map, see the
by Using Hierarchical Policy Maps" section on page
A policy-map and a port trust state can both run on a physical interface. The policy-map is applied before
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the port trust state.
When you configure a default traffic class by using the class class-default policy-map configuration
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command, unclassified traffic (traffic that does not meet the match criteria specified in the traffic
classes) is treated as belonging to the default traffic class (class-default).
OL-9775-08
"Classifying, Policing, and Marking Traffic on SVIs
37-64.
Catalyst 3750-E and 3560-E Switch Software Configuration Guide
Configuring Standard QoS
37-59