Re: HTTP/2 and TCP CWND

Hi Wes,

On Wed, Apr 17, 2013 at 12:48 PM, Wesley Eddy <wes@mti-systems.com> wrote:

>
> It's definitely misinformation given the dynamic nature of the
> CWND variable in TCP.  This is not a path property like MTU that
> can be thought of as relatively static, and it can change on short
> timescales with high granularity.
>

Granted, an old CWND measurement can be inaccurate. It's an informed guess
based on path performance. I'm sure we agree the path plays a
(non-definitive) role in this.

The alternative, IW, is an inaccurate guess too. Its an uninformed guess
and I don't see why we should assume it would be more accurate.

We can't argue that IW10 is strictly more conservative because my data says
it typically isn't.  (median SPDY CWND SETTING in firefox data is 30 x 1
session.. apples to apples that compares to at least 6 parallel HTTP/1
sessions of IW 10 each). Roberto suggested he's seen something similar. I'm
not sure that more conservative is a better thing anyhow but I don't see
how it applies in this case in any event.

-Patrick