3750 Limiting the Size of Priority Queue

Unanswered Question
Jul 31st, 2010

I have been wondering if it is possible to enable the EGRESS priority queue on an interface AND also limit the bandwidth used by that queue. Assume I would like to limit the priority queue to 25% of interface bandwidth for the purpose of this discussion.

Documentation is clear that srr-queue shape and share values are ignored if the priority queue is enabled.  There is a priority queue bandwidth command for the INGRESS queue  but not the EGRESS.  Can I accomplish this by limiting the buffer space  to 25% for queue 1?  Use the drop threshold configuration to drop at 25% of buffer space?  Is this even possible?  If so please advise the best way to accomplish this.  Thank you.

I have this problem too.
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Jayakrishna Mada Sat, 07/31/2010 - 22:51


The answer is NO. you cannot have priority queue enabled and give the Q only 25% bandwidth.

When Priority Q is enabled the Q gets 100% bandwidth. If there are any packets in the Q all those packets will be serviced before getting to the other queues.

you can use  "mls qos queue-set output qset-id threshold queue-id drop-threshold1 drop-threshold2 reserved-threshold maximum-threshold" command only set the buffer size and/or threshold and it has not nothing to do with bandwidth.

Hope that helps.



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