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New Member

3550 qos

I see that the 3550 has yet another version of QOS. Does this replace/superceed WFQ, Custom-Q, Priority-Q, CBWFQ-LLQ and all the other previous Q'ing that Cisco has come out with?

If so, how do you get the custom-Q effect of a rate and the priority-Q effect of a strict priority with the new 3550 QOS?

Also, why is it called Policing when it's really Shaping?




Re: 3550 qos

i do not see anything new with the 3550 QoS. Please check this URL,

It can do shaping as well as policing, when the outofprofile action is drop, then it is policing and when it is pass through then it is shaping

New Member

Re: 3550 qos

3550 qos uses MQC (module qos cli) and is CBWFQ. But since most of the feature of qos is done in hardware (which is good as it is faster), some of the functions needs to be done differently.

We support policing which is equivalent to rate-limiting. We don't support shaping. Catalyst 4000 sup3 does shaping per Tx Queue in hardware.

We do support strict priority queue on the egress. If you are coming from IOS (router) QoS world, it would take sometime for you to get adjusted to.

I suggest that you read the following tech tips

New Member

Re: 3550 qos

After reading through both pdf files, it doesn't do what CAR is able to do. The policing features is sufficient for ingress traffic, but lacking for egress traffic. Based on the pdf, the 3550 uses queueing & scheduling for egress traffic control. But the caveat is that it's only for the GE ports. How about the FE ports?

In short, I am trying to find the equivalent rate-limit command (see below) for the 3550 switch:-

int fastethernet0/1

rate-limit output 256000 32000 32000 conform-action transmit exceed-action drop

rate-limit input 256000 32000 32000 conform-action transmit exceed-action drop

Can the above be achieved on a 3550?



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