Cisco IE 4000, Software Configuration Manual

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Configuring QoS
Configuring QoS
Configuring Output Policy Maps with Class-Based-Weighted-Queuing
You use the bandwidth policy-map class configuration command to configure class-based weighted fair queuing
(CBWFQ). CBWFQ sets the relative precedence of a queue by allocating a portion of the total bandwidth that is available
for the port.
Follow these guidelines when configuring CBWFQ:

When configuring bandwidth in a policy map, all rate configurations must be in the same format, either a configured
rate or a percentage.

The total rate of the minimum bandwidth guarantees for each queue of the policy cannot exceed the total speed for
the interface.

You cannot configure CBWFQ ( bandwidth ) and traffic ( shape average ) or priority queuing ( priority ) for the same
class in an output policy map.

You cannot configure bandwidth as an absolute rate or a percentage of total bandwidth when strict priority (priority
without police) is configured for another class map.

You can configure bandwidth as a percentage of remaining bandwidth only when strict priority (priority without
police) is configured for another class in the output policy map.

When you configure CIR bandwidth for a class as an absolute rate or a percentage of total bandwidth, any excess
bandwidth that remains after servicing the CIR of all classes in the policy map is divided among the classes the same
proportion as the CIR rates. If you configure the CIR rate of a class to be 0, that class is not eligible for any excess
bandwidth and will receive no bandwidth.
Beginning in privileged EXEC mode, follow these steps to use CBWFQ to control bandwidth allocated to a traffic class
by specifying a minimum bandwidth as a bit rate or a percentage:
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.
4. bandwidth { rate | percent value | remaining
percent value }
Set output bandwidth limits for the policy-map class.

Enter a rate to set bandwidth in kilobits per second. The
range is from 64 to 1000000.

Enter percent value to set bandwidth as a percentage of the
total bandwidth. The range is 1 to 100 percent.

Enter remaining percent value to set bandwidth as a
percentage of the remaining bandwidth. The range is 1 to
100 percent. This keyword is valid only when strict priority
(priority without police) is configured for another class in the
output policy map.
You must specify the same units in each bandwidth configuration
in an output policy (absolute rates or percentages). The total
guaranteed bandwidth cannot exceed the total available rate.
5. exit Return to policy-map configuration mode.
6. exit Return to global configuration mode.