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Re: [pmtud] Improvement for the current PMTUD mechanism

John Heffner <jheffner@psc.edu> Mon, 17 October 2005 20:11 UTC

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From: John Heffner <jheffner@psc.edu>
Organization: PSC
To: pmtud@ietf.org
Subject: Re: [pmtud] Improvement for the current PMTUD mechanism
Date: Mon, 17 Oct 2005 16:08:40 -0400
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On Sunday 16 October 2005 03:02 pm, Fernando Gont wrote:
> > > Good point. I think the simple answer to this issue is to disable "fast
> > > retransmit" when there's a pending ICMP message. What do you think?
> >
> >This concerns me because it could have real side effects beyond pmtud. 
> > This might be a topic for tcpm.
>
> Actually, this cannot have interoperation problems. IIRC, TCP congestion
> control is not mandatory.
> And even then, fast retransmit is not specifically congestion control. If
> anything, I'm proposing to slow down the packet rate, rather than
> increasing it. (i.e. being more conservative).

In point of fact TCP congestion control is a MUST per RFC 1122, but this is 
entirely separate from the issue at hand. :-)

Any change to standards constraining how or when TCP may recover from a loss 
is pretty significant.  I think it is a discussion topic for tcpm.

  -John

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