Alan Hannan hannan at bythetrees.com
Sun Sep 14 16:52:29 UTC 1997

  Chris Said:
> > reasons, 1)  it's still significantly cheaper than long-haul circuits of the
> > same capacity,

  Your implication is wrt publically resold managed L2 networks such as
  ATM or Frame Relay.

  My earlier comments were addressing private management of one's
  own L1 network using L2 ATM or FR.

  Not to say either of us are wrong, just to frame the comments.

  Sean Doran said:
> My canonical explanation for this is that people are
> actually deluding themselves into thinking that ABR will
> work and the "quiet moments" across a large number of VCs
> can effectively be statmuxed out of existence without
> hurting goodput.

  I attempted a large diatribe here to examine what you mean by
  work, but my semantical misunderstandings lead me to instead ask

  	What do you mean by the statement "people .. thinking ...
	ABR will work"?

> The apocryphal reason is that people with too much
> influence in carriers' decision making processes are
> desperately trying to gain enough revenue to justify
> the ridiculously large amount of money spent on deploying
> ATM and convincing everyone it was the way the truth and
> the light of the future, even if that revenue isn't as
> profitable as selling raw bandwidth.  (cf. the canonical explanation)

  I'd agree with you if you were right, Sean.  However, this
  statement is bullocks.  It's not all a conspiracy, though it makes 
  for an interesting plot line for nanpcog.  The amount of money
  spent on ATM research is paltry relative to the current market.

  ATM achieved prominence in the ISP bb for two reasons:

  	o It worked
	o It was available

  ATM will retain prominence for some time for many reasons, some of
  which are:

	o It continues to work
	o It cotinues to grow in if speed
	o Investment in knowledge
	o Capital and Installation Investment
	o Investment in tools

  This stream of characters from you on how IP can do what ATM
  achieves is quite puzzling.

  Do you really, honestly think that IP has QOS built into it?  My
  recollection of the rfcs is not eidetic, but the TOS fields aren't
  supported by anyone but a nonstandard marketing plan, wrong?

  ATM allows one to build qos and particularly granular flow
  modification into one's <L3 network.

  Additionally, the ability to measure based upon preaggregated
  src-dest flows is exceedingly valuable data, available from L3
  routers with only a large expenditure of effort.

> The only ones I can think of right off the top of my head
> involve the counting problem.  (Modulo easy deployment of
> cisco's rate limiting and/or the ability to make tunnels fast).

  Easy and cisco in the same sentence.  Let me write this 
  down on my web page of quotes....

> Rather, I guess the question is, which of the "interesting
> abilities" (which I agree are interesting in a theoretical
> sense) are actually practically useful when running part
> of the Internet?

  See my note from several weeks ago and comments above.


  ps. for the record I am one of those who believe with most of my
      heart and not a small fraction of my unimpressive might that a
      ubiquitous fabric somewhere near L2 will make life good.  As bw
      increases linearly, the interconnections will increase
      geometrically.  Advancements in science will exponentially
      increase bw as the practical technology is used more commonly.
      I often wonder if people shouting IP IP IP are really worried
      about their own lack of malleability in dealing w/ other
      information pushing technologies.  That slight jab aside, the
      statistical aggregation of muxing ability of one protocol is
      not all that greater than the other, so whether the aggregation
      appears at L3 or L2 should, to the best of my knowledge and
      experience, be fairly approximate, at least today.  The
      downside to today's atm is the 1/ overhead and 2/ one
      cell/frame drop requiring all cells retransmitted by the
      higher layer (IP).

  pps.  I'm really not all that in love with ATM.  But it does work.
        If IP could do the things that ATM/FR can, then off we go.  My
        experience and knowledge say that managing a really large,
        dynamic, and robust network requires more than flexibility than L1
        pipes and L3 routers.  Something in the middle is needed to smooth
        out the corners.

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