Cisco IE 4000, Software Configuration Manual

Page: 641 / 1066

637
Configuring QoS
Configuring QoS
After you have created an output policy map, you attach it to an egress port. See Attaching a Traffic Policy to an Interface,
page 609 .
Use the no form of the appropriate command to delete an existing policy map or class map or to cancel the priority
queuing or policing for the priority class or the bandwidth setting for the other classes.
This example shows how to use the priority with police commands to configure out-class1 as the priority queue, with
traffic going to the queue limited to 20000000 bps so that the priority queue never uses more than that. Traffic above
that rate is dropped. The other traffic queues are configured as in the previous example.
Switch(config)# policy-map policy1
Switch(config-pmap)# class out-class1
Switch(config-pmap-c)# priority
Switch(config-pmap-c)# police 200000000
Switch(config-pmap-c)# exit
Switch(config-pmap)# class out-class2
Switch(config-pmap-c)# bandwidth percent 50
Switch(config-pmap-c)# exit
Switch(config-pmap)# class out-class3
Switch(config-pmap-c)# bandwidth percent 20
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config)# interface GigabitEthernet1/17
Switch(config-if)# service-policy output policy1
Switch(config-if)# exit
Configuring Output Policy Maps with Weighted Tail Drop
Weighted tail drop (WTD) adjusts the queue size (buffer size) associated with a traffic class. You configure WTD by using
the
queue-limit policy-map class configuration command.
Follow these guidelines when configuring WTD:

Configuring WTD with the queue-limit command is supported only when you first configure a scheduling action,
such as bandwidth , shape average , or priority . The exception to this is when you are configuring queue-limit in
the class-default .

You can configure and attach as many output policy maps as there are ports. Multiple output policy maps can use
the same queue-limit configuration. However, these policy maps can have only three unique queue-limit
configurations.

You can use the queue-limit command to configure the queue-limit for CPU-generated traffic.

When you use the queue-limit command to configure queue thresholds for a class, the WTD thresholds must be
less than or equal to the queue maximum threshold. A queue size configured with no qualifier must be larger than
any queue sizes configured with qualifiers.
13. exit Return to global configuration mode.
14. interface interface-id Enter interface configuration mode for the interface to which you
want to attach the policy.
15. service-policy output policy-map-name Attach the policy map (created in Step 3) to the egress interface.
16. end Return to privileged EXEC mode.
17. show policy-map Verify your entries.
18. copy running-config startup-config (Optional) Save your entries in the configuration file.
Command Purpose