Traffic Shaping on Cisco IOS

(Lazaros Agapides) #41

Hello Swapnil

Shaping will cause the traffic to adhere to the specific rate at which we have configured it even if there is available bandwidth to go faster. So in your example, the traffic would be limited to approximately 100 Mbps. Even if the queue limit is increased, the excess traffic still gets buffered even if there is no congestion on the same interface.

It is possible to configure shaping such that it can burst up to the speed of the physical interface. This is described in the following lesson:

With policing however, you are able to specify what happens if traffic exceeds the preconfigured settings where you can specify if it will be dropped or allowed. More about policing can be found here.

I hope this has been helpful!


(Swapnil K) #42

Okay…So lets say I am bursting it to full capacity of the interface for default class and there are already priority queues available to be served on the same physical interface so does those priority queues get affected if the bc and be for default class is configured equal to the cir??

(Rene Molenaar) #43

Hi Swapnil,

It depends on how you configure this. For example:

policy-map PRIORITY
 class class-default
  priority 64
policy-map SHAPING
 class class-default
  shape average 48000   
   service-policy PRIORITY

Don’t mind the values, I just picked something. The shaper is the “outside” policy and the priority queue is the “inside” policy. Your priority queue is affected by the shaper. Depending on the values you set, the shaper might shape the traffic of your priority queue or not.