[9233] in North American Network Operators' Group
Re: Coincidence...
daemon@ATHENA.MIT.EDU (Koen De Vleeschauwer)
Fri May 9 12:33:22 1997
From: Koen De Vleeschauwer <koen@EU.net>
To: kwe@6SigmaNets.com (Kent W. England)
Date: Fri, 9 May 1997 18:06:54 +0200 (MET DST)
Cc: michael@memra.com, nanog@merit.edu
In-Reply-To: <3.0.1.32.19970508105336.0071f1d8@mail.cts.com> from "Kent W. England" at May 8, 97 10:53:36 am
>
> At 02:48 PM 07-05-97 -0700, Michael Dillon wrote:
> >
> >I though that ATM cell sizes were so small in order to better support
> >real-time voice and video.
>
> The original ATM compromise was designed to avoid screwing up echo
> cancellation on the last mile loops which is very sensitive to delay and
> hard to adjust since it is old fashioned analog hardware and not digital.
> That is one of the more difficult aspects of the new xDSL technology is
> dealing with echo cancellation and crosstalk in those crummy old two-wire
> circuits.
>
Part of the story. US, Japanese and European telco manufacturers had different
perceptions of 'optimal' atm cell size. Depending upon the mix voice/video/data
different results were obtained; believe 32 and 64 byte were mentioned.
The powers that be decided upon a compromise and chose a value 'in the middle'
causing everyone to redesign their equipment. The compromise value was not a
power of two. Must have been '89 or thereabouts.
regards,
Koen
======= ___ === Koen De Vleeschauwer, Network Engineer,
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