traffic-shape rate on Ethernet 100M

Unanswered Question
Jun 11th, 2007

I have several questions around traffic shaping on a 100M Ethernet connection into a carrier.

We used traffic-shape rate 30000000 750000 0 4096

The object was to rate limit the 100M interface to 30Mbps to conform to the carriers policing policy. This created a 25msec interval that the shaping is done for, and should limit the router (2801) to sending at 30M with no "Excess Burst" (the "0") above 30M.

I have not been able to measure the results (live network), so I'm curious if anyone has observed how accurate the shaping is.

I do have a couple additional questions.

by default, the 2801 seems to select 25msec as the interval to use. Can you go to a shorter interval? What is the minimum?

and the last field is buffer, but expressed in bps (range 0 - 4096). What does that mean?

If traffic exceeds the shaped rate too long, eventually packets will be discarded when the buffer is full. How do I know how much buffering there is? and where would I look for a count of the dropped packets?

Lastly, the carrier is shaping using a Catalyst 5500 which puts us into an ATM VC. Does anyone know what interval the Catalyst uses to shape? I'm concerned that if it's less than 25msec, that it will see my burst of traffic at the start of my 25msec window as non-conforming to the subscribed rate. (experiencing packet loss ~4% during peak hours) Carrier initially claimed we must be bursting 100M at them.

Thanks - Glen

I have this problem too.
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