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QOS 6509 v12.2(17d)SXB10 - COS mapping to Q

6509 has WS-X6724-SFP, WS-X6748-GE-TX (RcvQ-1Q8T, xmtQ-1P3Q8T) and Sup720. I have questions about the command:

wrr-q cos-map q# t# cos1 ....... cos8

Question 1: To one queue, only One COS value can be assigned or more ??

Q.2. If one COS can be assigned to more than 1 Q than how will the switch dequeue traffic of one cos from different qos to maintain TCP transmit order (sequence#) ??

At present, I have voice traffic with cos=5, and all other traffic with cos=0 (besides control traffic with cos6-7). How best can I use all the Queues?? Default config assigns cos 0 to only Q#1, and cos 2,3,4 to Q#2. Q#2 is unused since I donot have any traffic in cos2,3,4 at present. Can I use Q#2 for cos=0 traffic ??

Any ideas / clues to best config in this situation ?

1 REPLY

Re: QOS 6509 v12.2(17d)SXB10 - COS mapping to Q

Hello,

a general word first: Queueing will only happen, when there is an overload situation on the specific interface under consideration. If there is no overload condition all traffic will be forwarded with line speed, i.e. with lowest possible delay.

In case there is an overload situation, frames/packets have to be stored before they are sent. What you basically do is to sort traffic you want to prioritize or give "better" treatment into specific queues. This is done "per frame/packet" which means a CoS value can only be sorted into one queue.

On the other hand you can also sort other CoS values in the same Queue.

You could therefore specify for example:

1) CoS 5 (voip) goes into priority queue

2) Cos 6,7 (control) goes into another queue

3) CoS 3 (usually voip signaling, which you didn´t mention) yet another queue

4) CoS 0,1,2,4 another queue

Config will (partially) look like this:

wrr-queue cos-map 1 1 5

wrr-queue cos-map 2 1 6 7

wrr-queue cos-map 3 1 3

wrr-queue cos-map 4 1 0 1 2 4

Please check the number of the priority queue and the values used for threshold, I don´t really remember them.

Hope this helps! Please rate all posts.

Regards, Martin

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