buffer bloat and packet pacing

Nick Hilliard nick at foobar.org
Thu Sep 3 12:04:34 UTC 2015


On 03/09/2015 11:56, Saku Ytti wrote:
> 40GE server will flood the window as fast as it can, instead of
> limiting itself to 10Gbps, optimally it'll send at linerate.

optimally, but tcp slow start will generally stop this from happening on
well behaved sending-side stacks so you send up ramping up quickly to path
rate rather than egress line rate from the sender side.  Also, regardless
of an individual flow's buffering requirements, the intermediate path will
be catering with large numbers of flows, so while it's interesting to talk
about 375mb of intermediate path buffers, this is shared buffer space and
any attempt on the part of an individual sender to (ab)use the entire path
buffer will end up causing RED/WRED for everyone else.

Otherwise, this would be a fascinating talk if people had real world data.

Nick



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