too many routes

Richard Irving rirving at
Thu Sep 11 20:15:49 UTC 1997

Ok. I will bite, although I hate to open my mouth, as my shoe always
seems to bee-line for it.. ;}

Sean M. Doran wrote:
> "Chris A. Icide" <chris at> writes:
> > We use ATM for two
> > reasons, 1)  it's still significantly cheaper than long-haul circuits of the
> > same capacity,

> 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 don't think so.... how about the ability to mix voice,
 MPEG, and IP on the same pipe ? Or, how about that with ABR my delay
across the 
ATM fabric is reduced when I have more bandwidth open. (POTS is low on
during this "theoretical moment in time") A couple milliseconds and a
few extra Mbs can count ;)

> people deploy modern SONET/SDH muxing and terminal equipment.
> > 2) it provides some interesting abilites that are only
> > now beginning to show up in the mainstream IP hardware.
> Ok, I'll bite: which ones?

  Oh, 2 things come to mind, my variability throughout an ATM cloud is
greatly reduced versus a routing cloud, a cell requires WAY less time to
cross a switches backplane, versus a  packet through a router. And
seriuosly less time to determine where to send it...

   Ok. So, maybe Cisco's Flow Switching approaches VBR having a bad hair
day. (and tuned for SERIOUS tolerance, CDVT=10,000), but certainly not
traditional routing. 

  And, on ATM, my neighbors traffic never bothers ME. Unless I am
sending to him, and he is running lossy, then it affects him ONLY...
Most ATM switches have massive backplanes, the problem is usually the
port/pipe of the greedy carrier, and does not affect a neighbor. The
greed mongers can trash their own ports/pipes, but not yours... (now, if
you happen to have paths through a monger.... sigh...) 

 I can't really remember the last time I experienced HOL on my ATM ports
(Historical Jibe: ;)

  On ATM QOS is available now. IP is getting there. The only REAL
problem with ATM's QOS, at this time, is the ability for IP to allocate
it ...... (At least for those who run the latest spec ATM nets) Legacy
are not being brought into this.....

 I wouldn't mind if you weren't my (ATM) neighbor. ;) (And a GOOD one at

>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 above.


mailto://[email protected]

      A technical with too much influence in a carriers decision making
desperately trying to gain enough revenue to justify the ridiculously
amount of money he spent on deploying ATM, and convincing everyone it IS
the way, the truth, and
the light of the future, even if it isn't CHEAPER than selling raw
bandwidth ;>

     Quality Rules.

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