nanog mailing list archives

Re: ATM vs. DS3


From: "Dorian R. Kim" <dorian () blackrose org>
Date: Fri, 11 Jul 1997 09:04:39 -0400 (EDT)

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



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