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Wrr-queue cos-map value differ between access switch and disturbtion switch

If the wieghted round robin differs in value from the 2950 access switch to the 3550 distutbution switch does it matter on the end on the of cos or priority queue set at the desination.

Example:2950 access switch:

wrr-queue bandwidth 10 20 40 0

wrr-queue cos-map 1 0 1

wrr-queue cos-map 2 2 3

wrr-queue cos-map 3 4 5

wrr-queue cos-map 4 6 7

mls qos map cos-dscp 0 8 16 26 34 46 48 56

Example:3550 disturbution Sw:

interface FastEthernet0/1

description Trunk

switchport trunk encapsulation dot1q

switchport trunk allowed vlan 1-4,10

switchport mode trunk

duplex full

mls qos trust cos

wrr-queue bandwidth 10 20 40 40

wrr-queue cos-map 1 0 1

wrr-queue cos-map 2 2 3

wrr-queue cos-map 3 4

wrr-queue cos-map 4 5 6 7

priority-queue out

Thank You

Mark

1 REPLY
Bronze

Re: Wrr-queue cos-map value differ between access switch and dis

Hi,

If you want to know whether the QoS policy at source affects the policy at destination switch, I believe that it won't affect CoS or priority queue set at the destination side. Because this WRR is meant for sharing of LOCAL bandwidth resources and mapping of CoS values to corresponding priorirty queues locally.

For eg, assuming your setup like this one...

Src --> Access switch-1 --> Distribution Switch --> Access Switch-2 --> Dest

Then, the WRR configuration at "Access switch-1" affects bandwidth sharing of the link between that switch and "Distribution switch" only.

According to your setup, taking one CoS value for which the configuration differs b/w 2950 and 3550, it gives increase in latency for that traffic. It's good to maintain uniformity throughout the network.

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