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Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter20 Co nf iguring QoS
Configuring QoS
Configuring the Egress Expedite Queue
You can ensure that certain packets have priority over all others by queuing them in the egress expedite
queue. This queue is serviced until it is empty and before the other queues are serviced.
Beginning in privileged EXEC mode, follow these steps to enable the egress expedite queue:
To disable the egress expedite queue, use the no priority-queue out interface configuration command.
Allocating Bandwidth among Egress Queues
You need to specify how much of the available bandwidth is allocated to each queue. The ratio of the
weights is the ratio of frequency in which the WRR scheduler dr ops pac kets fr om e ach que ue.
Beginning in privileged EXEC mode, follow these steps to allo cat e ba nd width to ea ch que ue:
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 mls qos Enable QoS on the switch.
Step3 interface interface-id Enter interface configuration mode, and specify the egress 10/100
Ethernet interface.
Step4 priority-queue out Enable the egress expedite queue, which is disabled by defau lt.
When you configure this command, the WRR weight is affected
because there is one fewer queue participating in WRR. This means that
weight4 in the wrr-queue bandwidth command is ignored (not used in
the ratio calculation).
Step5 end Return to privileged EXEC mode.
Step6 show running-config Verify your entries.
Step7 copy running-config startup-config (Optional) Save your entries in the configuration file.
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 mls qos Enable QoS on the switch.
Step3 interface interface-id Enter interface configuration mode, and specify the egress 10/100
Ethernet interface.