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default bandwidth allocation of class class-default in CBWFQ

I am seeing varying or unqualified documentation on CCO regarding how much bandwidth the default class in CBWFQ gets by default. Some documents suggest it will get any remaing bandwidth not assigned to other classes. Some documents are ambiguous at best regarding this. My understanding was that the default queue in 12.0.5 andlater releases got the remaining bandwidth by default and was treat as WFQ by default.

However, I am testing on a 3745 with 12.2.15T and seeing the default queue get NO bandwidth unless specifiaclly using the bandwidth command.

Anyone else runinto this


Re: default bandwidth allocation of class class-default in CBWFQ

The bandwidth allocation does vary according to the IOS releases. But it will usually be WFQ for default classes.

The class-default class is used to classify traffic that does not fall into one of the defined classes. Once a packet is classified, all of the standard mechanisms that can be used to differentiate service among the classes apply. The class-default class was predefined when you created the policy map, but you must configure it. If no default class is configured, then by default the traffic that does not match any of the configured classes is flow classified and given best-effort treatment.

By default, the class-default class is defined as flow-based WFQ. However, configuring the default class with the bandwidth policy-map class configuration command disqualifies the default class as flow-based WFQ.

Check out for more details:

Configuring the Class-Default Class Policy

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