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Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
OL-9639-06
Chapter 33 Configuring QoS
Understanding QoS
Port Shaping
To configure port shaping (a transmit port shaper), create a policy map that contains only a default class,
and use the shape average command to specify the maximum bandwidth for a port.
This example shows how to configure a policy map that shapes a port to 90 Mbps, allocated according
to the out-policy policy map configured in the previous example. The service-policy policy map class
command is used to create a child policy to the parent:
Switch(config)# policy-map out-policy-parent
Switch(config-pmap)# class class-default
Switch(config-pmap-c)# shape average 90000000
Switch(config-pmap-c)# service-policy out-policy
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config)# interface fastethernet0/1
Switch(config-if)# service-policy output out-policy-parent
Switch(config-if)# exit
Parent-Child Hierarchy
The switch also supports parent policy levels and child policy levels for traffic shaping. The QoS
parent-child structure is used for specific purposes where a child policy is referenced in a parent policy
to provide additional control of a specific traffic type.
The first policy level, the parent level, is used for port shaping, and you can specific only one class of
type class-default within the policy. This is an example of a parent-level policy map:
Switch(config)# policy-map parent
Switch(config-pmap)# class class-default
Switch(config-pmap-c)# shape average 50000000
Switch(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:
Switch(config)# policy-map child
Switch(config-pmap)# class class1
Switch(config-pmap-c)# priority
Switch(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:
Switch(config)# policy-map parent
Switch(config-pmap)# class class-default
Switch(config-pmap-c)# shape average 50000000
Switch(config-pmap-c)# service-policy child
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config)# interface fastethernet0/1
Switch(config-if)# service-policy output parent
Switch(config-if)# exit