Re: [tcpm] Increasing the Initial Window - Notes

[Jerry Chu <[e-mail]>]

On Thu, Nov 11, 2010 at 2:58 AM, Michael Welzl <[e-mail]> wrote:

>
> 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?
>

One solution to safely migrate to IW10 for browsers opening multiple
connections is to mandate browsers that open X connections, when X is, e.g.,
> 4 to set the initial receive window to 3 (assuming OSes allow initrwnd to
be set on a per connection basis). But I don't know how this can be
enforced...

Jerry


> Cheers,
> Michael
>
>