[10620] in North American Network Operators' Group
Re: ATM vs. DS3
daemon@ATHENA.MIT.EDU (Dorian R. Kim)
Fri Jul 11 09:32:10 1997
Date: Fri, 11 Jul 1997 09:04:39 -0400 (EDT)
From: "Dorian R. Kim" <dorian@blackrose.org>
To: "Alex.Bligh" <amb@xara.net>
cc: "nanog@merit.edu" <nanog@merit.edu>
In-Reply-To: <199707110915.KAA00177@diamond.xara.net>
On Fri, 11 Jul 1997, Alex.Bligh wrote:
> > I've used 20% as the general ATM overhead now for almost two years, and have
> > been poo-pooed by lots of people claiming that it wasn't anywhere near that
> > bad.
>
> Our inhouse figure is 23%. That was an empirical test of a traffic
> generator comparing performance to Cicso HDLC. This might be slightly
> pessimistic as Cisco traffic shaping (yes, even though you can't
> see it, it is there working) is really very aggressive and with bursty
> traffic it tends to prefer underfilling the line to overfilling it.
I'm not sure if this is pessimistic. When we ran calculations based on
packet size distribution of CICNet, we got 23% as well, and I believe Peter's
calculations based on ICM traffic agreed with this also.
-dorian
