[Tmrg] Proposal to increase TCP initial CWND

fred at cisco.com (Fred Baker) Mon, 19 July 2010 14:11 UTC

From: fred at cisco.com (Fred Baker)
Date: Mon, 19 Jul 2010 07:11:14 -0700
Subject: [Tmrg] Proposal to increase TCP initial CWND
In-Reply-To: <AANLkTimFEGfPJo9rjTw6oNPmwuHkEFBmAX1Ps2yYsUWh@mail.gmail.com>
References: <AANLkTil937lyUzRvUtdqd2qdl9RN7AZ-Mo_cT-dtmqXz@mail.gmail.com> <923833DA-FC31-4D30-96A5-48D4D072DBD3@cisco.com> <AANLkTimFEGfPJo9rjTw6oNPmwuHkEFBmAX1Ps2yYsUWh@mail.gmail.com>
Message-ID: <67225862-FF5A-4B3B-B681-C07E5A705B35@cisco.com>

"Typical" varies by vendor and software implementation. On Cisco products, the default IOS configuration gives 40 buffers in the queue. 

On Jul 19, 2010, at 1:12 AM, Jerry Chu wrote:

> On Sat, Jul 17, 2010 at 11:53 PM, Fred Baker <fred at cisco.com> wrote:
>> This is essentially the point of concern I raised to them; I also raised the point that what works well in the broadband Internet is quite a bit different than Internet access in parts of the world that have slower typical access rates.
> I'd like to point out Google's services are not restricted to just
> broadband users. Also from our experiements
> some of the greatest latency improvments of a larger IW seem to have
> come from users behind slow or highly
> multiplexed links.
> Do you know how much buffer space a typical dial-up (e.g., 56Kbps)
> access router provides?
> Jerry
>> On Jul 17, 2010, at 11:27 PM, Lachlan Andrew wrote:
>>> - An increase in retransmissions from 3.94% to 5.79% seems very
>>> significant, if that rate reflects the loss rate.  Although described
>>> as a 1.85% increase, it seems likely to cause competing traffic to
>>> slow down by a factor of  sqrt(5.79/3.94).  Moreover, that is the
>>> increase in loss when (presumably) a *single* flow on that bottleneck
>>> increases its initial window.  How can we estimate the impact of *all*
>>> flows increasing their initial windows?
>> http://www.ipinc.net/IPv4.GIF