[nsp] Calculating ATM Cell transfer rates

sthaug at nethelp.no sthaug at nethelp.no
Wed Feb 25 12:06:14 EST 2004

> surely this would give you an inaccurate Cell rate - if
> we wanted to shape a PVC for 256Kbps - using Ciscos
> interpretation this would give you a cell rate of 603 cps
> based on 53 byte cells.  But 603 cps is only 231Kbps of
> actual payload data based on 48 bytes of payload per cell.
> Or am I mis-understanding the whole calculation process?

I am saying that the Cisco specification in kbps is based on 53 byte
cells. Thus if you want 256 kbps of *payload*, you have to specify
256*53/48 = 282 (or 283 if you round up) kbps in your Cisco router

As I mentioned, you can check this yourself by using suitable debug

Steinar Haug, Nethelp consulting, sthaug at nethelp.no

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