[Bloat] [e2e] [aqm] What is a good burst? -- AQM evaluation guidelines

Naeem Khademi naeem.khademi at gmail.com
Mon Dec 16 08:47:34 EST 2013


Bob, Fred and all

I'll copy/paste the question here again: "what is a good burst (size) that
AQMs should allow?" and/or "how an AQM can have a notion of the right burst
size?"

So, obviously, as Bob mentioned, I'm concerned about what AQMs should or
shouldn't do. The mission of dealing with packet bursts in addition to the
task of keeping the standing queue very low or minimal is part of an "AQM
evaluation criteria" I envision. While I do agree with all Fred's remarks,
I'm more concerned to have an answer for this, for where AQMs might get
deployed.

An example: when designing my AQM X should I care about 64K TSO-generated
bursts to safely pass without dropping or not?  Does the answer (whatever
it is) also apply to the burst sizes typical of multimedia traffic, etc.?
if the answer is "yes", should an AQM design be actively aware of what
application layer does in terms of sending bursty traffic or not? and to
what extent if yes?

Regards,
Naeem

On Mon, Dec 16, 2013 at 8:34 AM, Fred Baker (fred) <fred at cisco.com> wrote:

>
> On Dec 15, 2013, at 2:57 PM, Bob Briscoe <bob.briscoe at bt.com>
>  wrote:
>
> > Fred,
> >
> > Jonathan Morton, Michael Scharf & I took Naeem's question to mean "What
> should an AQM assume the size of a good burst is?" whereas I think you and
> David C-B took the question to mean "What should an end-system take the
> size of a good burst to be?".
>
> I can't comment on what he means. I took the question as "what should a
> system that is in receipt of what it might consider a 'burst', and more
> especially a 'good burst', to be?"
>
> I don't know that a sending transport (which is to be distinguished from
> the queueing arrangement in that same system) or a receiving system *has* a
> definition of a "good" or "bad" burst. The one is sending data, which in
> the context of y two examples might be a good or bad idea, and the other is
> receiving it. From the receiver's perspective, the data either arrived or
> it didn't; if it arrived, there is no real argument for not delivering it
> to its application...
>
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