ATM Wide-Area Networks (was: sell shell accounts?)

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Date: Tue, 23 Jul 1996 14:28:27 -0400
From: Paul Ferguson <pferguso@cisco.com>
Subject: Re: ATM Wide-Area Networks (was: sell shell accounts?)
  [...]
It depends on what you mean when you say 'performance'. I think
there is more and more interest being vested in ATM inefficiency,
and alternate technologies to better efficiency in the long-haul.

Recall Jerry Scharf's numbers; they're indicative of the issue.
  [...]
HDLC framing bytes = 3080633605 HDLC efficiency = 97.72
ATM framing bytes = 3644304857 ATM efficiency = 82.61
ATM w/snap framing bytes = 3862101043 ATM w/snap efficiency = 77.95

At a certain point, some of these arguments about ATM efficiency sound a bit
like saying FDDI is terrible because 4B/5B encoding is only 80% efficient.

I think a more interesting measure of the value of ATM versus other
wide-area technologies is some sort of measure of throughput per dollar.

-tjs

2

At a certain point, some of these arguments about ATM efficiency sound a bit
like saying FDDI is terrible because 4B/5B encoding is
only 80% efficient.

But FDDI has a *great* admission-control scheme.

However, I almost concede your point. :slight_smile: [*]

I think a more interesting measure of the value of ATM
versus other wide-area technologies is some sort of
measure of throughput per dollar.

No kidding.

  Sean.

P.S.: [*] almost, because in an application where one is
      using ATM as a single point-to-point PVC along a
long-haul trunk that is to be used essentially exclusively
for IP traffic, the cell tax seems really excessive.
Given the movement towards cisco's packet-over-SONET,
should that work and should others implement similar and
preferably interoperable point-to-point interfaces, I will
have to withdraw my almost-concession, except in cases
where people _really_ want to do point-to-multipoint stuff.