too many routes

Sean M. Doran smd at
Thu Sep 11 18:13:14 UTC 1997

"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.

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)

There are cases, however, involving inter-carrier
handoffs where muxing at the virtual tributary/virtual
container level doesn't work particularly well end-to-end,
thus making ATM an alternative to SDH<>PDH<>SDH
conversions.  These cases are becoming rarer over time as
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?

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).

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?


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