[ih] Re: Global congestion collapse
craig at aland.bbn.com
Sun Dec 26 13:10:41 PST 2004
In message <000a01c4eb87$f15db8a0$0200a8c0 at fun>, "Michael Welzl" writes:
>* were admins aware that this patch would reduce your own rate and
> might make things worse for you if you're the only one who installs it?
> e.g., think of 1000 * unresponsive UDP vs. 1 * TCP - across a single
> bottleneck - in this scenario, a single unresponsive flow would be
> better off than a single TCP flow.
Actually the great thing about Van's patch was that the existing TCPs
were so bad, that being the only one running Van's patch meant you
got *better* performance. Only later did people figure out how to
create unresponsive TCP's that were well-behaved enough they'd win in
[Reaching deep into my brain, my recollection is that Van's worked
better because it (a) did RTT estimation right and (b) slow start allowed
it to correctly probe available bandwidth, whereas existing implementations
just hammered at not enough bandwidth. Happy to be corrected, this was
>* Van Jacobson's paper came out in August 1988. I think that the first
> RFC which says "you MUST implement congestion control" is
> RFC 1122 - which came out October 1989. What happened in between?
> Was it just a patch flying around and word of mouth ("c'mon, install it,
> we'll all be better off")?
The patch came out well before August of 1988.
And yes, it was word of mouth -- or perhaps, better said, notes on the
TCP-IP list. There's a note from Van on 11 Feb 88 discussing the work
and a note from Dan Lynch soon thereafter inviting people to a tutorial
at Interop about it. There's a Jan 87 note from Van saying he and
Mike Karels are experimenting with the mods. I tried to find the
actually software release but all I could find was the official release
on 6 Dec 88 (whereas the patch had been around for a while by then).
If you don't have the TCP-IP archives, well worth reading (I grabbed
what I could when I realized they might be endangered and appear
to have much of the list from 82 to 91).
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