6500 strict priority queue size ???

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Jan 10th, 2006
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Hi guys,

Is it possible to adjust the 6500 line cards strict priority queue size? Most cards assign 85% of thebandwdith to the oridinary queues and 15% to the strict priority queue. It seems that it is not possible to adjust the size of the strict priority queue.


I have a customer who has numerous T1's encapsulated into IP and the gross amount of traffic is about 200Meg, all of which is real time. If I were to mark this as DSCP 46 (COS 5) it would saturate the strict priorty queue leading not only to performance problems on the T1's but would also starve the rest of the traffic on the 1Gig WAN link.


Any thoughts guys?


Regards, Steve

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pkhatri Tue, 01/10/2006 - 03:12
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Hi Steve,


The expedite queue is a strict-priority queue that is used until it is empty before using one of the WRR queues. Therefore, it does not make sense to allocate a bandwidth percent to it. Only WRR queues need to be assigned bandwidth percentages.


In your case you will find that the strict priority queue will always be serviced first and not face any starvation.


Hope that helps,

Paresh.

kirkster Tue, 01/10/2006 - 03:37
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Hi Paresh,

Thanks for your reply. I think I didn't explain myself properly. There is a bandwidth allocation of memory for each port. The priority queue gets 15%by default. I have so much priority queue traffic that I want to increase this to 25% because all of it is strict priority (its voice after all). If this canot be done then I will be losing packets of voice since the priorty queue will not be able to accomdate the amount of traffic.


Best regards, Steve

pkhatri Tue, 01/10/2006 - 03:52
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Hi Steve,


Maybe I'm still not getting you but here are my thoughts anyway..


Since the priority queue is served to exhaustion, you should not have a buildup of traffic in that queue at all (since as soon as a packet gets there, it will be sent out). Therefore, on a Gig interface, the only time there will be a buildup of traffic on the strict priority queue is when the offered traffic is in excess of 1Gbps.


Paresh.

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