Shaping with Burst up to interface speed

This topic is to discuss the following lesson:

Thanks a lot Rene. Excellent post !!!

Thanks for this clear and concise lesson, much appreciated

3.200 50ms: How did you get the 3.200?

Hi Paul,

In my example, the Tc of 50 ms is a requirement.

The bottom link has a CIR of 64kbps, that’s 64000 bits per second (1000ms).

64000 bits = 1000ms

Divide it by 10 and we get:

6400 bits = 100ms

To get to 50ms, divide it by 2:

3200 bits = 50 ms.


Hi, Rene

What do you mean the physical access rate? For me it is not clear, could give an explanation on this?

Hello Stefanio.

When Rene refers to the physical access rate, he is referring to the maximum speed available on the physical interface. In this specific case:

Rene is referring to the maxiumum speed that the Serial interface S0/0 is capable of providing.

I hope this has been helpful!


Hi Rene,

That was a great bunch of posts. Just for the benefit of students, can you please state this?

Bc and Be - are they supposed to be expressed in bits, bytes ? vary with different families/models of Cisco devices?


Hello Ayyappan

Looking at the below output of the context sensitive help, we can see that both Bc and Be are measured in bits:

This image is from the following lesson:

Now Rene doesn’t mention which platform or which IOS he is using, however, it should be the same for most platforms.

I hope this has been helpful!