Re: [tcpm] Is this a problem?

Mahesh Jethanandani <mahesh@cisco.com> Thu, 08 November 2007 16:57 UTC

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Date: Thu, 08 Nov 2007 08:56:57 -0800
From: Mahesh Jethanandani <mahesh@cisco.com>
Organization: Cisco Systems Inc.
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Subject: Re: [tcpm] Is this a problem?
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Ethan Blanton wrote:
> Yes; however, I agree with Joe (and others) that in the situation you
> are *actually* trying to solve, this is not particularly relevant.  If
> you are short on resources, the distinction between "not making
> progress due to zero window" and "not making progress for some other
> reason" does not seem important.  As previously mentioned, zero window
> does _not_ indicate a malicious host in any way.
>   
Where is the fairness argument in knocking connections off without 
making distinctions? A connection that is not making progress because of 
congestion in the network is a transient behavior and is very different 
from a connection that continues to advertise a zero window. The former 
is much harder to do and requires TCP stack changes. Zero window 
connection can be made to happen on a whim (as we successfully did) on a 
large number of connections from a user level program with little or no 
privileges.

/mahesh


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