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Re: [pmtud] Improvement for the current PMTUD mechanism

Fernando Gont <fernando@gont.com.ar> Wed, 12 October 2005 22:13 UTC

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Date: Wed, 12 Oct 2005 17:25:35 -0300
To: John Heffner <jheffner@psc.edu>, pmtud@ietf.org
From: Fernando Gont <fernando@gont.com.ar>
Subject: Re: [pmtud] Improvement for the current PMTUD mechanism
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At 04:03 p.m. 11/10/2005, John Heffner wrote:

> > As stated in my draft, my proposal does not address the issue of blackholes
> > or broken implementations.
> > It's an *improvement* for the current PMTUD mechanism, rather than a
> > replacement for it.
>
>This is not a black hole issue.  In this case, classical pmtud works fine but
>adding in a loss check causes pmtud to "fail" such that all packets get
>fragmented.  This is not a total connection failure like a black hole, but is
>bad for a number of reasons.

I disagree. If packets get fragmented, then PMTUD is simply NOT working. 
Those implementations are simply broken. There may be other crazy behaviors 
out there.


>http://www.hpl.hp.com/techreports/Compaq-DEC/WRL-87-3.pdf
>http://www.psc.edu/~jheffner/drafts/draft-mathis-frag-harmful-XX.html

Yes, I'm aware of these papers, and have already read them.


--
Fernando Gont
e-mail: fernando@gont.com.ar || fgont@acm.org






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