Re: [Codel] sprout

[Keith Winstein <keithw@mit.edu>]

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Thank, Dave.

We have a Web site with more info, a talk, and source code (
http://alfalfa.mit.edu) if anybody is interested.

Something that may interest folks here is that we compared
Sprout-over-unlimited-buffer with TCP-Cubic-over-CoDel on these
cellular-type links. That is, a scenario where the network operators
implemented CoDel inside the LTE/UMTS/1xEV-DO base station (for the
downlink) and the phone manufacturers implemented CoDel inside the
"baseband" chip for the uplink.

Bottom line results is that for the case where a cellular user can control
all their own flows, it's roughly a wash. To a first approximation, you can
fix bufferbloat on a cellular network *either* by putting CoDel inside the
base station and baseband chip (and otherwise running the same endpoint
TCP), *or* by changing the endpoints but leaving the base station and
baseband chip unmodified.

Obviously we benefit dramatically from the per-user queues of the cellular
network. By contrast, in a typical house with a bufferbloated cable modem
where one user can cause big delays for everybody else, you can't fix
bufferbloat by fixing just one endpoint. We will have some results soon on
whether you can fix it by fixing all the endpoints (but still leaving the
"bloated" gateway intact).

Cheers,
Keith

On Wed, Jul 10, 2013 at 3:30 PM, Dave Taht <dave.taht@gmail.com> wrote:

> I haven't been paying a lot of attention to rmcat and webrtc until
> recently, although I'd had a nice discussion with keith on it a while
> back..
>
> this particular thread sums up some interesting issues on that front.
>
> http://www.ietf.org/mail-archive/web/rmcat/current/msg00390.html
>
> --
> Dave Täht
>
> Fixing bufferbloat with cerowrt:
> http://www.teklibre.com/cerowrt/subscribe.html
>

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