[Bloat] Pointer to Van's Queue Rant and a small plea on AQMs

Kathleen Nichols nichols at pollere.com
Wed Feb 9 16:51:06 PST 2011

I've read through the posts here and Jim's slides and this is a great
topic. I hope progress
is made.

I thought I'd supply a pointer to a talk (a rant) Van gave in July of
06. I believe he reused
some of this in another talk last year, but here it is:


Also, as someone who spent a lot of time examining the dysfunctionality
of 93 RED and
various changes Van came up with in response to the problems: examine
any AQM very
carefully. It's likely not working the way you think it is. What I
learned is that almost
anything works with nicely behaved long-lived TCPs and that almost
nothing works
well with mixtures of mice and elephants. It's also instructive to
examine what is really
happening when your AQM drops packets. We found that 93 RED spent a lot
of time
doing what we called "forced drops" which means you are in the "drop
part of your control law. What we would find with 93 RED were a bunch of
back to
back drops. There's tons of stuff on this in our unfinished "RED in a
different light"
paper, but look at the first 10 slides or so of
and you'll see some of it without wading through a lot of boring prose.

So, please, please, don't make a "fix" that is perhaps worse than the
original problem.

	(also known as "Van's wife Kathy")

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