Re: [tcpm] Is this a problem?

Joe Touch <touch@ISI.EDU> Wed, 21 November 2007 00:02 UTC

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Date: Tue, 20 Nov 2007 16:01:21 -0800
From: Joe Touch <touch@ISI.EDU>
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To: Lloyd Wood <>
Subject: Re: [tcpm] Is this a problem?
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Lloyd Wood wrote:
> At Tuesday 20/11/2007 07:12 -0500, Mark Allman wrote:
>>> Why does congestion control require standardization, when every
>>> client/server application out there is perfectly capable of doing it?
>>> To achieve consistent behaviour across the widest range of
>>> applications...
>> I think this is a complete mis-characterization.  The answer is that
>> congestion control is standardized because congestion control is about
>> dealing with a *shared resource*.  We can do that control from a number
>> of places in the stack and people have advocated for each of them at
>> different points.  But, *where* that functionality exists is a second
>> question after we establish that the functionality needs to exist and we
>> need to standardize on it.  This persist business is not about
>> controlling a shared resource, but about controlling a *local
>> resource*.  Why should the community standardize local resource control?
> The community standardised TCP window size advertisements. That's a local resource control issue, surely?

That's something you have to tell the other end, i.e., it requires a
change to the protocol on the wire. This one can be implemented without
any change to the protocol at all - entirely at the app layer.

>> That seems absurd to me.  So, to me, arguing about where to mitigate the
>> persist stuff is putting the cart before the horse.  First, we'd need to
>> establish some reason to standardize local resource control.
> because it's useful?

Useful is a fine metric for a new protocol, not for mucking with such a
ubiquitous and established one unnecessarily, IMO.


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