7210 QoS - equivalent to Cisco generic traffic shaping?

[jameswang]

Does ALU provide a feature similar to this? I've read through the 7210 guides, 7750 adv config guide, official QoS book, and the ALU QoS class books, and can't find mention of it.

Simply put, does ALU on any of MPLS routing boxes ALU you to recieve a burst on SAP ingress, that is greater than NNI egress, and have the ability to buffer and hold instead of performing tail drop.

Physical lashup
Host A --1Gpbs-- ALU 7210-1 ------- 300Mbps Egress-rate-------- ALU 7210-2 --1 Gbps-- Host B

So for example. Host A transmits to host B at an average rate of 150Mbps, well below the CIR/PIR, and then bursts instantaneously over 1 second at 1Gpbs.

I see that the 7210 has slope policy RED/WRED options, but those appear to be specifically on whether to allow packets to be buffered toward the scheduler, and NOT specifically to perform any method of classic router traffic shaping by holding and smoothing bursts above the egress PIR.

Can anyone confirm on the capabilities here, and for that matter, can the 7705, or 7750 perform classic traffic shaping?

[mivens]

As I understand it, you can think of the PIR as the rate at which traffic is shaped out of a queue. The MBS parameter determines the threshold at which traffic is no longer shaped and is dropped. Another way of saying this is the Maximum Burst Size (MBS) determines the ability of the 7210 to hold and smooth bursts. When the buffer is exhausted, it will have to tail drop but WRED can be used to configure a drop probability as the buffer fills.

For your example, you might want to look at the Port Level Egress Rate-Limiting feature.