Subject: Re: ATM drivers...
To: None <Havard.Eidnes@runit.sintef.no>
From: Herb Peyerl <email@example.com>
Date: 04/08/1998 05:47:48
> If I'm not much mistaken, the SDH STM-1 (which for these purposes
> should be the same as SONET OC-3) section overhead removes 9/270 of
> the bandwidth and the path overhead consumes another 1/270, giving you
> 155.520Mbit/s * 260/270 which comes out to 149.760Mbit/s which can be
> used for ATM cells. If the above mentioned value was observed with
> ttcp you'd have to additionaly take into account the ATM cell header
> overhead (which comes out to approx. 10%), possible AAL5 encapsulation
> overhead and the overhead possibly caused by the last cell in the IP
> packet not being completely filled with "user" data.
well, I can't argue with the math. Maybe there's something wrong with
'ttcp'? I did observe it and even pasted it into a conversation I was
having with a number of folks at the time, including Jason and Charles
as well as others whom I can't remember...
On a day to day basis however, I only use at most, 10mbit of the link
since that's the size of our active PVC.