Subject: Re: TCP versus real-time apps in an int-serv internet

From: [email-masked] (Noel Chiappa)
Date: Tue, 15 Nov 94 12:35:03 -0500

From: Jon Crowcroft <[email-masked]>

    > there was a strategy which would allow a "bad guy" to get more than an
    > even share of the bandwidth. ... it seems like it should exist.

    people have done it - its called running two ftp's at once

Well, that's an obvious example. I was more looking for a modification to
TCP that allows a single TCP connection to use more than an even share of
bandwidth, in a universe full of VJCC TCP's.

    you're right, it works fine, but it isn't "bad" quite in the sense you
    mean...

Well, I can see two plausible definitions for "bad".

The weaker one is one in which all comers do not share the available bandwidth
evenly - a word I far prefer to "fairly", which is so politically loaded now
as to make me throw up on hearing it. (This is, of course, modulo resource
allocation mechanisms which deliberately share out bandwidth non-evenly, and
enforce those allocations.)

The stronger one is one of wastefully; if I'm sending packets which aren't
used, or useful, then that's "bad" in a stronger sense.

It's trivial to define algorithms that are "wasteful bad". I strongly suspect
that there are algorithms which are "non-evenly bad" without being very
"wasteful bad", at least in world in which their "competition" is "nice guys"
like VJCC.

If so, than in a world without resource allocation controls, and with limited
resource, and a pure ecosystem of VJCC's for competition, you should
eventually expect to see competitors arrive. (Remember that species-diversity
poor ecosystems are particularly vulnerable to predators; c.f. the spruce
budworm in Canada, and the Morris worm in the Internet! :-) Am I sure it will
happen? Well, not everybody is a nice guy. (C.f. personal computer viruses.)
What exactly the eventual ecological balance, in terms of workable algorithms,
will be after that point I'm not sure.

Am I missing something?

	Noel

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From: Jon Crowcroft <[email-masked]>
Date: Tue, 15 Nov 94 18:20:05 +0000

Noel

try reading parekh's thesis...

 jon