[Codel] Work on absence of a universal queue management / scheduling scheme

Anirudh Sivaraman sk.anirudh at gmail.com
Tue Oct 29 00:04:59 EDT 2013


I would be grateful for the list's feedback re: our new paper that
attempts to show that there is no universal AQM or scheduling scheme,
and proposes extending SDN to the data plane to allow a switch to
implement different scheduling and queue management algorithms, even
after being installed. The paper, along with instructions to reproduce
its results, is available here:

We compared three queue-management schemes on a bottleneck gateway in
simulation: CoDel running on a single queue (as described in "man
tc-codel"), CoDel with per-flow queues (fq_codel, as described in "man
tc-fq_codel"), and per-flow queueing with long DropTail queues. It
turns out that depending on the objectives desired by the traffic
running across the gateway, any one of these schemes can be better
than any other -- i.e. A>B>C>A and A>C>B>A. In other words, we don't
think there is likely to be a 'best' AQM scheme

Our proposal to address the absence of a universal in-network
configuration is a switch data plane that's flexible enough to
implement new scheduling and queue management schemes. To be clear,
this work is merely a position paper at this point, and needs a lot
more thought before such a design is feasible at line rates on
switches with an aggregate capacity reaching 1 Terabit/sec. We are
presenting this next month at HotNets, so we are grateful for any
feedback from the list.


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