[e2e] TCP Performance over WWAN

Detlef Bosau detlef.bosau at web.de
Sun Aug 14 11:37:46 PDT 2011

Just a very first reply:

On 08/14/2011 06:43 PM, Jim Gettys wrote:
> With aggregation, some packets may get through, and others be damaged
> (802.11n gives you a bit mask telling you which are intact and which are
> damaged).  This all gets complicated, as, for example, you don't want to
> drop three packets from the same flow, etc. So the drivers have had to
> all get reworked for 802.11n.  So there is buffering after initial
> transmission, so that packets can be retransmitted later if they failed
> in their first attempt.

At a first glance, I think this may cause packet order distortion?

How do you deal with TCP then?

> Dave Taht started putting together an OpenWrt distribution (called
> CeroWrt) for bufferbloat work we're doing, as you might imagine, we ran
> right into these issues.  In his test case, it was insane time even for
> ping, much less TCP.

Detlef Bosau
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