Cisco Catalyst 3550 Series User Manual

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Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter 29 Configuring QoS
Configuring Standard QoS
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:
To return to the default bandwidth setting, use the no wrr-queue bandwidth interface configuration
command.
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
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
wrr-queue bandwidth weight1 weight2
weight3 weight4
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.
Step 5
end Return to privileged EXEC mode.
Step 6
show mls qos interface queueing Verify your entries.
Step 7
copy running-config startup-config (Optional) Save your entries in the configuration file.

Cisco Catalyst 3550 Series Specifications

General

Brand	Cisco
Model	Catalyst 3550 Series
Category	Network Router
Language	English