NAP Solutions

Mon Nov 17 15:45:39 UTC 1997

Tony Li <tli at juniper.net> writes:

> A SONET MPLS switch makes for a very interesting
> exchange. 

Yes, for all the reasons you outlined, and because we've
been talking about it for a couple years, this what I
would deploy in the short run if I were interested in
getting large-provider business.

Having a circuit per peer has some advantages with respect
to failure modes, but is expensive.  Assuming that there
is still a per bit per second per kilometre cost even for
inhouse applications, if a reliable alternative existed, I
expect that would be used, particularly as the growth
curve of inter-provider traffic necessitates expansion of
the private peering circuits.

I would hope that people at Sprint, UUWHO (and ANS and
MCI) and the various other places using private peering
points are thinking about migrating from a "you buy one
circuit i will buy one circuit" model to a more general
"we will run an exchange point here, you bring circuits to
us; you run an exchange point there, we will bring
circuits to you, they will be running an exchange point
there we will both bring circuits to that" one, although
actually making a decision to do this would be dependent
on costs and the reliability of new big fast routers and
MPLS implementations and interoperability.

One fat physical circuit that buys you N peers is
probably going to be cheaper than N not-so-fat physical
circuits at one peer each, in line costs, manageability
and capital expenses (router ports etc.)

Of course, the key downside to using a SONET MPLS
switch/router is back to scaling.  

A question for you Tony.  What does one do when one has an
N port MPLS switch/router and has filled all N ports with
traffic?  Consider that each of the N ports will become
fuller and that there will probably be a desire or
requirement for N+1 ports with more to come.

The lesson of the Gigaswitches and the ATM counterparts is
that scaling beyond a single switch is hard.

I don't have an answer, given what I know and can imagine
about near-term technology (as opposed to stuff I want you
and Crashco to build :) )

> the forseeable future. 

How long is that these days anyway?

Anyway, other than the "what do you do other than give up
on port density when you have more traffic or connections
than one MPLS switch can handle" concern, I am in complete
agreement with you, surprise surprise.

	Sean.