Traffic shaping question

[illinois.tollway]

I have a 2800 series router that is connected to a metro-ethernet circuit, and I need to do some traffic shaping on it.

The circuit is 50mbs and the CIR is 30mbs

Since I have been seeing some performance problems when we burst above 30mbs, it seems like traffic shaping is the way to go, but there are several different ways to implement it.

Can someone give me some pointers on the best config to use here?

[Joseph W. Doherty · Accepted solution]

policy-map ShapeFor30Mb
class class-default
shape average 30000000

(egress interface)
int X
service-policy output ShapeFor30Mb

[illinois.tollway]

DO I need to do anything additional in the policy, such as

queue-limit 32768 packets

?

[Joseph W. Doherty]

Ah, well that's an "it depends" answer.

It depends on what your BDP is, and whether you're looking for the optimal queue depth to support TCP at full transfer rate. It also depends on what the default depth of the shaper's queues will be. Then it depends on a trade-off, you need to decide on, between increasing queue depth to avoid drops, but by doing so, you'll also add to queuing latency.