33-24
Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
OL-9639-07
Chapter 33 Configuring QoS
Understanding QoS
Note You cannot configure bandwidth and traffic shaping (shape average) or priority queuing (priority) for
the same class in an output policy map.
This example shows how to set the precedence of output queues by setting bandwidth in kilobits per
second. The classes outclass1, outclass2, and outclass3 and class-default get a minimum of 40000,
20000, 10000, and 10000
kbps. Any excess bandwidth is divided among the classes in the same
proportion as the CIR rated.
Switch(config)# policy-map out-policy
Switch(config-pmap)# class outclass1
Switch(config-pmap-c)# bandwidth 40000
Switch(config-pmap-c)# exit
Switch(config-pmap)# class outclass2
Switch(config-pmap-c)# bandwidth 20000
Switch(config-pmap-c)# exit
Switch(config-pmap)# class outclass3
Switch(config-pmap-c)# bandwidth 10000
Switch(config-pmap-c)# exit
Switch(config-pmap)# class class-default
Switch(config-pmap-c)# bandwidth 10000
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config)# interface fastethernet 0/1
Switch(config-if)# service-policy output out-policy
Switch(config-if)# exit
Note When you configure CIR bandwidth for a class as an absolute rate or percentage of the total bandwidth,
any excess bandwidth remaining after servicing the CIR of all the classes in the policy map is divided
among the classes in the same proportion as the CIR rates. If the CIR rate of a class is configured as 0,
that class is also not eligible for any excess bandwidth and as a result receives no bandwidth.
This example shows how to allocate the excess bandwidth among queues by configuring bandwidth for
a traffic class as a percentage of remaining bandwidth. The class outclass1 is given priority queue
treatment. The other classes are configured to get percentages of the excess bandwidth if any remains
after servicing the priority queue: outclass2 is configured to get 50 percent, outclass3 to get 20 percent,
and the class class-default to get the remaining 30 percent.
Switch(config)# policy-map out-policy
Switch(config-pmap)# class outclass1
Switch(config-pmap-c)# priority
Switch(config-pmap-c)# exit
Switch(config-pmap)# class outclass2
Switch(config-pmap-c)# bandwidth remaining percent 50
Switch(config-pmap-c)# exit
Switch(config-pmap)# class outclass3
Switch(config-pmap-c)# bandwidth remaining percent 20
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config)# interface fastethernet 0/1
Switch(config-if)# service-policy output out-policy
Switch(config-if)# exit
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