Cisco ME 3400 Series, Руководство по настройке программного обеспечения

Страница: 689 / 1138

33-63
Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
OL-9639-07
Chapter 33 Configuring QoS
Configuring QoS
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.
• You cannot configure more than two unique threshold values for the WTD qualifiers ( cos , dscp ,
precedence , or qos-group ) in the queue-limit command. However, there is no limit to the number
of qualifiers that you can map to those thresholds. You can configure a third unique threshold value
to set the maximum queue, using the
queue-limit command with no qualifiers.
•
A WTD qualifier in the queue-limit command must be the same as at least one match qualifier in
the associated class map.
• In an output policy map, when you configure a queue-limit for a unique class, all other output policy
maps must use the same format of qualifier type and qualifier value. Only queue-limit threshold
values can be different. For example, when you configure class A queue-limit thresholds for
dscp
30 and dscp 50 in policy-map1 , and you configure class A queue-limits in policy-map 2, you must
use dscp 30 and dscp 50 as qualifiers. You cannot use dscp 20 and dscp 40 . The threshold values
can be different, but different threshold values would create a new unique queue-limit configuration.
Beginning in privileged EXEC mode, follow these steps to use WTD to adjust the queue size for a traffic
class:
Command Purpose
Step 1 configure terminal Enter global configuration mode.
Step 2 policy-map policy-map-name Create a policy map by entering the policy map name, and enter
policy-map configuration mode.
Step 3 class { class-map-name | class-default } Enter a child class-map name, or class-default to match all
unclassified packets, and enter policy-map class configuration
mode.
•
If you enter a class-map name, you must perform Step 4 to
configure a scheduling action (
bandwidth , shape average ,
or priority) before you go to Step 5 to configure queue-limit.
•
If you enter class-default, you can skip Step 4.
Step 4
bandwidth { rate | percent value | remaining
percent value }
or
shape average target bps
or
priority
Configure a scheduling action for the traffic class. For more
information, see the
“Configuring Output Policy Maps with
Class-Based-Weighted-Queuing” section on page 33-54 , the
“Configuring Output Policy Maps with Class-Based Shaping”
section on page 33-56
, the “Configuring Output Policy Maps with
Port Shaping” section on page 33-57 , or the “Configuring Output
Policy Maps with Class-Based Priority Queuing” section on
page 33-58
.