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Date: Thu, 8 May 1997 12:39:18 -0700 (PDT)
From: Tom Samplonius <tom@sdf.com>
To: Bill Fenner <fenner@parc.xerox.com>
cc: Shawn Carey <smc@servtech.com>,
        "Daniel O'Callaghan" <danny@panda.hilink.com.au>,
        freebsd-hackers@freebsd.org
Subject: Re: FTP Performance 
In-Reply-To: <97May8.111829pdt.177486@crevenia.parc.xerox.com>
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On Thu, 8 May 1997, Bill Fenner wrote:

> Tom Samplonius <tom@sdf.com> wrote:
> >  How would this misconfiguration occur?  Just two routers with
> >mis-matched MTU/MRU sizes?
> 
> No, the only way for PMTU discovery to fail is for a router to not
> return ICMP fragmentation required errors.  I don't know how to
> configure a router to do this, since it's required by RFC1812,
> but perhaps there's a firewall in the way.
> 
>   Bill

  Yes, many sites block most if not all ICMP.  Any way to disable mtu
detection?

Tom