Cisco Systems A9014CFD Class-Based Weighted Fair Queuing, 24-21, Routerconfig# policy-map parent

Chapter 24 Configuring QoS

Understanding QoS

The first policy level, the parent level, is used for port shaping, and you can specific only one class of type class-defaultwithin the policy. This is an example of a parent-level policy map:

Router(config)# policy-map parent

Router(config-pmap)# class class-default

Router(config-pmap-c)# shape average 50000000

Router(config-pmap-c)# exit

The second policy level, the child level, is used to control a specific traffic stream or class, as in this example:

Router(config)# policy-map child

Router(config-pmap)# class class1

Router(config-pmap-c)# priority

Router(config-pmap-c)# exit

Note The total of the minimum bandwidth guarantees (CIR) for each queue of the child policy cannot exceed the total port-shape rate.

This is an example of a parent-child configuration:

Router(config)# policy-map parent

Router(config-pmap)# class class-default

Router(config-pmap-c)# shape average 50000000

Router(config-pmap-c)# service-policy child

Router(config-pmap-c)# exit

Router(config-pmap)# exit

Router(config)# interface gigabitethernet0/1

Router(config-if)#service-policy output parent

Router(config-if)# exit

Class-Based Weighted Fair Queuing

You can configure class-based weighted fair queuing (CBWFQ) to set the relative precedence of a queue by allocating a portion of the total bandwidth that is available for the port. Use the bandwidth policy-map class configuration command to set the output bandwidth for a class of traffic as a percentage of total bandwidth, or a percentage of remaining bandwidth.

Note When you configure bandwidth in a policy map, you must configure all rates in the same format. The total of the minimum bandwidth guarantees (CIR) for each queue of the policy cannot exceed the total speed of the parent.

•When you use the bandwidth policy-map class configuration command to configure a class of traffic as a percentage of total bandwidth, it represents the minimum bandwidth guarantee (CIR) for that traffic class. This means that the traffic class gets at least the bandwidth indicated by the command, but is not limited to that bandwidth. Any excess bandwidth on the port is allocated to each class in the same ratio in which the CIR rates are configured.

Note You cannot configure bandwidth as a percentage of total bandwidth when strict priority (priority without police) is configured for another class in the output policy.

	Cisco ASR 901 Series Aggregation Services Router Software Configuration Guide
OL-23826-09		24-21