Cisco Support Community
Community Member

Grant bandwidth (CBWFQ?)

Hi Team,

i am new to the community so i greet you all!

My doubts and problems are related to the need to shape the traffic of a class granting a minimum bandwidth.

We have a 7206-VXR so we have Gigabit physical interfaces, our SP is granting 200Mbps.

The shape is working fine but the bandwidth command don't trigger couse, for my router, there's no congestion.

I think that this is a common problema and maybe i am trying to solve in the wrong way.

Any suggestion is appreciated

Thanks in advance


Everyone's tags (5)
Cisco Employee

Re: Grant bandwidth (CBWFQ?)

Hi Denis,

Shaping using the 'shape' cli defines the max rate for a class; whereas, the 'bandwidth' cli defines the minimum bandwidth guarantee for that class under functional congestion.

For example,

policy-map test

class A

  shape average percent 20

class B

   bandwidth percent 10

  class C

    bandwidth percent 30

- Traffic through class A will *always* get shaped to 20% of intf bandwidth. Doesn't matter whether the interface is congested or not.

- Traffic through class B and Class C will get a *minimum* guarantee of 10 and 30% of intf bandwidth when the interface is congested. When the interface is not congested, then there is really no need for a queueing policy (~ bandwidth cli) and the queueing part of the policy won't kick in. So, class B / class C can basically use the entire intf bandwidth if there is no traffic through the other (bandwidth) classes. However, should the physical interface be congested (tx_ring is full) then queueing kicks in and each class is given a minimum guarantee that's configured. The remaining bandwidth is shared amongst the bandwidth classes in the ratio of guarantees.

- Abhi

CreatePlease to create content