[Tmrg] Proposal to increase TCP initial CWND

lachlan.andrew at gmail.com (Lachlan Andrew) Tue, 20 July 2010 00:34 UTC

From: lachlan.andrew at gmail.com (Lachlan Andrew)
Date: Tue, 20 Jul 2010 10:34:38 +1000
Subject: [Tmrg] Proposal to increase TCP initial CWND
In-Reply-To: <4C44CE07.7080503@gmx.at>
References: <AANLkTil937lyUzRvUtdqd2qdl9RN7AZ-Mo_cT-dtmqXz@mail.gmail.com> <4C44CE07.7080503@gmx.at>
Message-ID: <AANLkTilbLfzI3YJQOIMzTC6IhaHtYJ3Lb91ACGpCcQEG@mail.gmail.com>

On 20 July 2010 08:13, Stefan Hirschmann <krasnoj at gmx.at> wrote:
>
> Third:
> The question about the size of the web objects.
> I used Firebug to monitor a Google search request. There were 21 web
> transfers and only 8 of these were larger than 4 KB.
> packet). An analysis in 2008 [2] showed that 93% of all connections send
> less than the 4380 bytes. In other words: For 93% of all connections,
> there is no congestion control at all.
>
> Tra?c analyses (like [21]) showed that around half of transferred data
> come from ?ows transferring fewer than 4036 bytes and it is allowed to
> send 4036 bytes in the ?rst RTT without using any congestion control
> [RFC 3390].

It is a good point that the 7% of congestion controlled flows produce
50% of the data, and that 50% is congestion controlled (or rate
limited by the application).  Would it help for the Google folk to
check what fraction of data (not flows) would be devoid of congestion
control if the IW were increased?

> Six:
> HTTP Pipelining is AFAIK not widely used by now.
...
> So the browser producer would slow down the connection
> if he/she reduces the number of parallel connections. So I am sure the
> browsers won't reduce this number.
> For TMRG the consequence is: We have to model it with six parallel
> connections because this will be the real world.

Interesting point.  Do you think that the "test suite" draft* should
include one scenario where all flows are split into six, or should all
tests be like that?

*(yes, it is still breathing, just!)

Cheers,
Lachlan

-- 
Lachlan Andrew? Centre for Advanced Internet Architectures (CAIA)
Swinburne University of Technology, Melbourne, Australia
<http://caia.swin.edu.au/cv/landrew>
Ph +61 3 9214 4837