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Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter 20 Configuring 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 drops packets from each queue.
Beginning in privileged EXEC mode, follow these steps to allocate bandwidth to each queue:
Command
Purpose
Step 1
configure terminal
Enter global configuration mode.
Step 2
mls qos
Enable QoS on the switch.
Step 3
interface interface-id
Enter interface configuration mode, and specify the egress
Gigabit-capable Ethernet interface.
Step 4
priority-queue out
Enable the egress expedite queue, which is disabled by default.
When you configure this command, the WRR weight and queue size
ratios are 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).
Step 5
end
Return to privileged EXEC mode.
Step 6
show running-config
Verify your entries.
Step 7
copy running-config startup-config
(Optional) Save your entries in the configuration file.
Command
Purpose
Step 1
configure terminal
Enter global configuration mode.
Step 2
mls qos
Enable QoS on the switch.
Step 3
interface interface-id
Enter interface configuration mode, and specify the egress
Gigabit-capable Ethernet interface.