From owner-freebsd-net@FreeBSD.ORG  Tue Feb 13 17:27:11 2007
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Date: Tue, 13 Feb 2007 09:15:02 -0800
From: Eli Dart <dart@es.net>
Organization: Energy Sciences Network
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To: Stephen.Clark@seclark.us
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Cc: freebsd-net@freebsd.org
Subject: Re: pmtud problem
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Stephen Clark wrote:

> if the pc sends a packet of 1460 bytes with the DF bit set shouldn't the
> freebsd 4.9 system
> send back an icmp dest unreachable - fragmentation needed and DF bit set?

Are you blocking icmp with a firewall filter?

		--eli


> $ sysctl -a | grep mtu
> net.inet.tcp.path_mtu_discovery: 1
> 
> Now if I change the mtu of the gre to 1412 everything works.
> 
> Any insight would be appreciated.
> 
> Thanks,
> Steve

- --
Eli Dart                                         Office: (510) 486-5629
ESnet Network Engineering Group                  Fax:    (510) 486-6712
Lawrence Berkeley National Laboratory
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