Catalyst hardware - different QoS queues per switch

Unanswered Question
May 9th, 2007

Hi all. I've been working on setting up bandwidth shaping on my C3560, C6500 (native), and C2950 switches, and have noticed that each switch maps DSCP/CoS values to egress queues differently. Why is this?

It seems that do apply shaping correctly across the LAN, I would need to be consistent in giving each DSCP/CoS value the same bandwidth, but this is making it difficult. I realize I could easily re-map the values to different queues, but the hardware itself has different buffer sizes per queue. So for example, the 6500 has CoS 2,3,4 mapped to Q2 w/ 20% of buffer on the linecard I'm using, the C3560 has CoS 2,3 in Q3, and 4,6,7 in Q4, with each queue getting 25% of the buffer space.

Maybe I'm making more out of this than I should, but it seems like a lot of work to remap the CoS/DSCP to queue settings, as well as the SRR/WRR buffer settings.

I have this problem too.
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jbayuka Tue, 05/15/2007 - 06:21

Cat 3750 Metro Series switches with the Hierarchical Queuing Framework features on the Enhanced Service ports is able to deliver traffic shaping, 2 rates 3 colors policers, and other advance QoS features on its 8000 queues. With the set of rich

features and flexibility, the Service Providers will be able to offers differentiated services to multiple customers serviced by

Cat 3750 Metro Series switch.

If you want to know more please click following URLs:

http://www.cisco.com/en/US/products/hw/switches/ps708/products_white_paper0900aecd803e5269.shtml

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