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class (policy-map)
Release
12.2(33)MRA
15.0(1)MR
Usage Guidelines
Policy Map Configuration Mode
Within a policy map, the class (policy-map) command can be used to specify the name of the class whose
policy you want to create or change. First, the policy map must be identified.
To identify the policy map (and enter the required policy-map configuration mode), use the policy-map
command before you use the class (policy-map) command. After you specify a policy map, you can
configure policy for new classes or modify the policy for any existing classes in that policy map.
Class Characteristics
The class name that you specify in the policy map ties the characteristics for that class—that is, its
policy—to the class map and its match criteria, as configured using the class-map command.
When you configure policy for a class and specify its bandwidth and attach the policy map to an
interface, class-based weighted fair queueing (CBWFQ) determines if the bandwidth requirement of the
class can be satisfied. If so, CBWFQ allocates a queue for the bandwidth requirement.
When a class is removed, available bandwidth for the interface is incremented by the amount previously
allocated to the class.
The maximum number of classes that you can configure for a router—and, therefore, within a policy
map—is 64.
Predefined Default Class
The class-default keyword is used to specify the predefined default class called class-default. The
class-default class is the class to which traffic is directed if that traffic does not match any of the match
criteria in the configured class maps.
Tail Drop or WRED
You can define a class policy to use either tail drop by using the queue-limit command. When using tail
drop, note the following points:
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Cisco MWR 2941 Router Command Reference, Release 15.0(1)MR
36
Modification
This command was integrated into Cisco IOS Release 12.2(33)MRA. This
release does not support the fragment, insert-before, or service-fragment
parameters.
This command was integrated into Cisco IOS Release 15.0(1)MR. This
release does not support the fragment, insert-before, or service-fragment
parameters. The release also does not support Weighted Random Early
Detection (WRED).
The queue-limit command cannot be used in the same class policy, but can be used in two class
policies in the same policy map.
You can configure the bandwidth command when the queue-limit command is configured in a
class policy. The bandwidth command specifies the amount of bandwidth allocated for the class.
For the predefined default class, you can configure the fair-queue (class-default) command. The
fair-queue command specifies the number of dynamic queues for the default class. The fair-queue
command can be used in the same class policy as the queue-limit command. It cannot be used with
the bandwidth command.
Cisco MWR 2941 Router Command Reference, Release 15.0(1)MR
OL-23890-01
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