Re: [tcpm] Increasing the Initial Window - Notes

Michael Welzl <michawe@ifi.uio.no> Thu, 11 November 2010 10:58 UTC

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From: Michael Welzl <michawe@ifi.uio.no>
To: Marco Mellia <mellia@tlc.polito.it>
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Cc: Mike Belshe <mbelshe@google.com>, tmrg <tmrg-interest@icsi.berkeley.edu>, Matt Mathis <mattmathis@google.com>, tcpm <tcpm@ietf.org>
Subject: Re: [tcpm] Increasing the Initial Window - Notes
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On Nov 11, 2010, at 11:49 AM, Marco Mellia 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...

... which is a good reason to open fewer connections. So that's a  
matter of bringing of bringing out an update of a web client with a  
different behavior for the case that a web server uses a larger IW.  
But how does the web browser know what the web server is doing? I  
guess they could exchange this information with HTTP. Hm. Are we  
getting somewhere here, or is this a dead end?

Cheers,
Michael