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Configuring QoS
Configuring QoS
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
1. configure terminal Enter global configuration mode.
2. policy-map policy-map-name Create a policy map by entering the policy map name, and enter
policy-map configuration mode.
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.
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 Configuring Output Policy Maps with
Class-Based-Weighted-Queuing, page 630, Configuring Output
Policy Maps with Class-Based Shaping, page 631, Configuring
Output Policy Maps with Port Shaping, page 632, or Configuring
Output Policy Maps with Class-Based Priority Queuing,
page 633.
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