Qos Problem

Unanswered Question
Jul 27th, 2007

i m having problem in a qos implementation so plz guide me where i m doing a mistake.

i have got 2 routers A and B. they r connected thru serial link with a bandwidth of 64k. ( i set the clock rate and the bandwidth on the A's serial interface which is my DCE side) now i have a ftp server connected on the lan of A. Client pc is connected at the lan of router B. i did a LLQ by matching the traffic of ftp from A to B and giving it the priority bandwith of 32k. now i have also used lan traffic generator to chok the bandwidth. now here is the problem. i have watched and read a hundred of times that PQ is always there even if there is no congestion means that 32k bandwidth will be reserved even if no traffic matching it is present, but wat i saw in the graph is that when i start any application it gets the complete 64k bandwidth why is that so ???? i have used 2500 and 2811 for this lab but the result are always same, can some1 guide me that is there a problem in cisco's implementation or m i doing something wrong.

any help would be appreciated


I have this problem too.
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pciaccio Fri, 07/27/2007 - 06:45

You have a good setup for testing QOS.. But one thing you need to keep in mind. Low Latency Queueing will not be invoked until you overrun the current hardware queues. Once these hardware queues are saturated then LLQ is invoked and your QOS parameters take effect.....What you need to do is saturate the link so to over run the output buffers. Verify your traffic generator is saturating the interfaces....Good Luck...

mchoo2005 Sun, 07/29/2007 - 16:00

LLQ is not the same as PQ. LLQ is basically CBWFQ combined with PQ. Hence, the behaviour is quite different from strict PQ configuration. As the previous poster said, LLQ only comes into effect if/when there is congestion, unlike PQ.


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