Cisco WS-C2960-24TC-S Software Guide - Page 546

Configuring Standard QoS Chapter 28 Configuring 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: Step 1 Step 2 Command configure terminal class-map [match-all | match-any] class-map-name Purpose Enter global configuration mode. 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. 28-46 Catalyst 2960 Switch Software Configuration Guide OL-8603-04