Subject: Re: MPLS,IETF, etc..

From: Bob Braden <[email-masked]>
Date: Sat, 1 Sep 2001 10:29:29 -0700 (PDT)

*> extremely difficult.  In solving the essential problem
  *> it was tasked for (reducing routing control/signaling
  *> overhead via a more efficient marriage of (routed) L3
  *> messages and (switched) L2 transports), MPLS (thanks
  *> to its tag switching ancestors) is, IMHO, an elegantly
  *> simple  solution. That a solution can exhibit simplicity

Simplicity, in this case, seems to be in the eye of the
beholder.  I don't get why label swapping is any simpler than
hop/hop forwarding.

Bob Braden

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From: [email-masked]
Date: Sun, 02 Sep 2001 01:06:43 -0400

On Fri, 31 Aug 2001 16:49:39 EDT, "Natale, Robert C (Bob)" said:
> To really jump the tracks here (since I'm pretty much just
> rambling on here anyway):  It could be argued that both the
> "dot com" mania and melt-down were attributable -- in large
> part -- to the same mix of evangelistic and journalistic
> misunderstanding of simplicity.

It wasn't simplicity.  It was investor stupidity.  Too many investors
saw the 'e-' in e-commerce and saw some mystical quality that glossed
over the 'commerce' - things that have been understood for hundreds
of years, like "cash flow" and "business plan".  I can guarantee that
even a cobbler in 1100AD understood "I buy leather for X, I sell shoes
for Y, and I need to sell enough shoes so that (Y-X)*n is enough money
that I don't starve".

Many of the dot-bombed had a *very* simple business plan:
"We'll burn investor money while we try to figure out how to make a
profit while giving away the content for free".  Now, this is a
perfectly valid business model - if you're a 501(c) charitable
organization and the investors are called "benefactors".

Now as for MLPS, it sounds to me like a good idea for its original
design goals, but is being promoted for so many other things that
many people are confused - Does it *really* slice, dice, *and*
make Julienne fries?

				Valdis Kletnieks
				Operating Systems Analyst
				Virginia Tech

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From: "J. Noel Chiappa" <[email-masked]>
Date: Sun, 2 Sep 2001 06:53:49 -0400

> From: Bob Braden <[email-masked]>

    > I don't get why label swapping is any simpler than hop/hop forwarding.

At the time when tag-switching (to give it its original name - well, actually,
as someone pointed out, it was Ipsilon's product that started the trend, and
tag-switching from Cisco was in some ways a marketing response, one that got
IETF'd) was conceived, it wasn't really feasible to build hardware router
chips of the kind we see today used in boxes from Juniper, etc. You just
couldn't get enough gates into a chip. Tag-switching was enough simpler that
fully-hardware processing of packets was doable.

However, that wasn't the only rationale behind tag-switching; it also allowed
networks to see and control traffic aggregates - and in particular, control
that aggregate over a path - something which is obviously impossible with a
hop-by-hop design. This a capability still sadly lacking in all versions of IP
today. That (among other things) was something that kept MPLS going after one
principal motivator (hardware packet processing) was no longer applicable.

In particular, the ability to manage traffic aggregates turned out to be
exactly what was needed when it came time to deal with fully-optical networks
(which don't want to turn the photon stream back into electrons, and parse the
electrons back into packets, at each switch), and so now there is MP*S.

Now, of course, MPLS has been morphed into "ATM-with-variable-length-cells"
(after the original ATM failed to take over the world); it remains to be seen
if that extensive set of capabilities is really what the world (a.k.a. market)
needs.

	Noel