Exchanges that matter...

Wed Dec 4 20:02:20 UTC 1996

On Wed, 4 Dec 1996, Danny Stroud wrote:

> What I meant was that the demand for traffic seems 
> to be growing faster than technologies ability to deliver it. Even with the 
> planned *new* technologies, I am predicting that there will be a point where 
> the traffic of the exchange points will need to bifurcate simply to be able to 
> process the load, i.e. more *smaller* exchange points all running at top 
> capacity of the available technology. 

If the argument is merely that LAN bandwidth cannot handle the demands
placed on them at the NAPs, I think that this is a weak argument for NAP
proliferation.

First of all, I doubt that NAPs do or will max out LAN technology.  It may
max out _cheap_ LAN technology, but so what?  Gigaswitches are a hell of a
lot cheaper than even ten T3s.  If gigabit ether develops with anything
like the speed that fast ether did, then doubly so.  Plus, isn't ATM
supposed to be infinitely scalable?  Why don't you have OC-3 or even
OC-12, whether it be ATM or IP/SONET?

Assuming that LAN technology is the limiting factor (to which I can't
really agree), why proliferate NAPs instead of constructing parallel
physical networks at the existing ones?  You can do bandwith aggregation
at Layer 2 just fine if you try, and without increasing network
complexity.  (I know there are problems with this approach, but it can be
done.  Plus, fewer NAPs, more time to spend doing it right.)

"But the routers can't process packets fast enough."  NAP proliferation
hurts rather than helps on this problem.  Sure, you have more aggregate
horsepower to throw at a problem, but from a simpleton's point of view it
looks like a roughly exponentially more complex routing state from which
to decide.  In any event, it definitely doesn't help.

You still haven't addressed the route flap problem.

One argument I'm sort of suprised that you haven't made is that multiple
NAPs make the network more redundant and, ergo, tolerant of failure.  Of
course, they don't.  Three NAPs per continent is plenty to serve this
purpose; anything over this is reckless.

> It's not exactly the same analysis of 
> costs for the final mile that drove the telco CO deployment, but the idea is 
> the same: sometimes available technology defines the strategy.

Sure it does.  I think that the argument that technology is forcing us to
more NAPs is a losing one, although it's certainly theoretically
plausible. 

> Any better?

Yep; keep 'em coming.

__
Todd Graham Lewis             Linux!                 Core Engineering
Mindspring Enterprises  tlewis at mindspring.com   (800) 719 4664, x2804