Re: [tcpm] TCP tuning

Jerry Chu <hkchu@google.com> Wed, 03 February 2010 19:09 UTC

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Date: Wed, 03 Feb 2010 11:10:22 -0800
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From: Jerry Chu <hkchu@google.com>
To: "SCHARF, Michael" <Michael.Scharf@alcatel-lucent.com>
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Subject: Re: [tcpm] TCP tuning
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On Wed, Feb 3, 2010 at 7:17 AM, SCHARF, Michael
<Michael.Scharf@alcatel-lucent.com> wrote:
>> This topic seems to be gaining momentum, and the WG should
>> take some time considering if there is work here for it.
>
> IMHO there could indeed be room for increasing the initial window. If
> most data transfers continue to be smaller than 3 MSS, a larger initial
> window would not necessarily cause harm, as it is seldomly used. Still,
> this would speed up those data transfers that currently suffer from
> Slow-Start.

Actually our data points to the contrary - the average web object and page
size have been rising steadily. E.g., the majority of our search responses
no longer fit in 3 MSS these days.

>
> In the past, I have played a little bit with an initial window e. g. of
> 10 MSS, and that worked surprisingly well.

Good to know!

>Also, one could combine a
> larger initial window with other mechanisms that would reduce the
> aggressiveness of the flow startup. Maybe it is indeed time to think
> about the Slow-Start once again.

We are planning to submit an I-D on raising initcwnd to 10MSS before
3/1 to be included in the upcoming IETF meeting.

Jerry

>
> Michael
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