COS

[bluesox123]

Dear All

Could someone please explain how Fair-Queue And WRED Work in the Default Queue

I Understand how they work on interfaces for just one of them

CLASS CLASS - DEFAULT

FAIR-QUEUE

RANDOM-DETECT

Yours

Jimmy

[Peter Paluch · Accepted solution]

Jimmy,

To my best knowledge, the WFQ activated in the class-default queue works on a per-flow basis. In other words, all traffic classified into the class-default class will be split into so-called conversation queues, each queue representing a single flow (hopefully - a hash function is used for that so multiple flows may eventually end up in the same queue). The WFQ will then schedule these queues using its fair queue algorithm. It is very similar to activating the WFQ on the entire interface.

I am not completely sure about the WRED in the class-default queue but I believe it does not work on per-flow but rather on per-class basis, i.e. it limits only the total number of packets in the class-default class. However, I will need to look this up.

Does this answer your question, or are you asking about something different?

Best regards,

Peter

[Joseph W. Doherty · Accepted solution]

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Posting

As Peter describes, both work within the class much as they do for an interface, especially WRED.

Some differences:

Within class-default you can use both, recall for interfaces it might be either/or.

Within CBWFQ, its class, whether single FIFO queue or multiple FQ queues competes for bandwidth with other explicit CBWFQ classes.  How this bandwidth is proportioned varies per IOS version.  For example, HQF FQ is is just FQ, prior to HQF, on many IOS based routers, FQ is actually WFQ (like an interface FQ).

[bluesox123]

Dear Peter And Joe

thank you for your help if i could i would split the rating

yours

Jimmy