Re: [tcpm] Increasing the Initial Window - Notes

Jerry Chu <hkchu@google.com> Thu, 11 November 2010 10:58 UTC

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Date: Thu, 11 Nov 2010 02:59:22 -0800
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From: Jerry Chu <hkchu@google.com>
To: Marco Mellia <mellia@tlc.polito.it>
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Cc: tcpm <tcpm@ietf.org>, Mike Belshe <mbelshe@google.com>, tmrg <tmrg-interest@icsi.berkeley.edu>, Matt Mathis <mattmathis@google.com>, Michael Welzl <michawe@ifi.uio.no>
Subject: Re: [tcpm] Increasing the Initial Window - Notes
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On Thu, Nov 11, 2010 at 2:49 AM, Marco Mellia <mellia@tlc.polito.it> wrote:
>
>
>>> I certainly won't object to this, if that's all it takes for
>>> standardization. Unfortunately the
>>> point for the non-convinced is they don't want ANY flows to use IW10
>>> for fear of hurting
>>> the performance of their flows.
>>
>> ... but here, your "browsers open tens of flows" argument totally holds. How is a web flow with IW10 worse than a browser opening tens of flows? If people only use it for the web, like Google has been successfully doing, this seems to be quite safe, based on experience.
>>
>> I'm curious what the opposition says to this  :)
>
> If today a brower opens 10 flows with a server using IW=1 you gets 10 packets equivalent IW.
> Increasing the IW to 10 leads to an equivalent IW of 100 packets. At that point, you DSL modem will definitively start dropping most of them...

But if we don't start thinking about how to scale these TCP
parameters, tomorrow (ok, maybe
in a couple of years) when browsers decide to open 20 or 30 flows
because they are frustrated
with low TCP parameters like IW, it will effectively be equivalent to
increasing IW to 10 today.
So do we want to do nothing and leave it all to apps, or try to take
some control of some key
TCP parameters back into TCP itself?

Jerry

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