Subject: [tcpm] IW10 Considered Harmful

From: Jim Gettys <[email-masked]>
Date: Fri, 26 Aug 2011 15:25:44 -0400

I just submitted draft-gettys-iw10-considered-harmful-00

http://www.ietf.org/id/draft-gettys-iw10-considered-harmful-00.txt

It is commenting on the proposal in
http://datatracker.ietf.org/doc/draft-ietf-tcpm-initcwnd/
which would change the TCP initial window from 4 packets to 10.

I believe this would be a serious mistake compounding problems already
present
for low latency applications, for the reasons outlined in my draft.
                    Best regards,
                                Jim Gettys

                        Abstract

The proposed change to the initial window to 10 indraft-ietf-tcpm-
initcwnd must be considered deeply harmful; not because it is the
proposed change is evil taken in isolation, but that other changes in
web browsers and web sites that have occurred over the last decade,
it makes the problem of transient congestion at a user's broadband
connection two and a half times worse. This result has been hidden
by the already widespread bufferbloat present in broadband
connections. Packet loss in isolation is no longer a useful metric
of a path's quality. The very drive to improve latency of web page
rendering is already destroying other low latency applications, such
as VOIP and gaming, and will prevent reliable rich web real time web
applications such as those contemplated by the IETF rtcweb working
group.