Allocating Bandwidth Among Egress Queues - Cisco Catalyst 3550 series Software Configuration Manual

Chapter 29 Configuring QoS
Command
Step 4 priority-queue out
Step 5 end
Step 6
show running-config
Step 7 copy running-config startup-config
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 dequeues packets from each queue.
Beginning in privileged EXEC mode, follow these steps to allocate bandwidth to each queue:
Command
Step 1 configure terminal
Step 2
mls qos
Step 3
interface interface-id
Step 4
wrr-queue bandwidth weight1 weight2
weight3 weight4
Step 5
end
Step 6
show mls qos interface queueing
Step 7
copy running-config startup-config
To return to the default bandwidth setting, use the no wrr-queue bandwidth interface configuration
command.
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Purpose
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).
Return to privileged EXEC mode.
Verify your entries.
(Optional) Save your entries in the configuration file.
Purpose
Enter global configuration mode.
Enable QoS on the switch.
Enter interface configuration mode, and specify the egress
Gigabit-capable Ethernet interface.
Assign WRR weights to the egress queues.
By default, all the weights are set to 25 (1/4 of the bandwidth is allocated
to each queue).
For weight1 weight2 weight3 weight4, enter the ratio, which determines
the ratio of the frequency in which the WRR scheduler dequeues
packets. Separate each value with a space. The range is 1 to 65536.
All four queues participate in the WRR unless the expedite queue
(queue 4) is enabled, in which case weight4 is ignored (not used in the
ratio calculation). The expedite queue is a priority queue, and it is
serviced until empty before the other queues are serviced.
A weight of 1 means that the minimum bandwidth is allocated for that
queue.
To allocate no bandwidth for a queue, use the wrr-queue cos-map
interface configuration command so that the available bandwidth is
shared among the remaining queues.
Return to privileged EXEC mode.
Verify your entries.
(Optional) Save your entries in the configuration file.
Catalyst 3550 Multilayer Switch Software Configuration Guide
Configuring Standard QoS
29-63