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To: Michael Smith <msmith@atrad.adelaide.edu.au>
cc: shovey@buffnet.net (Steve), terry@lambert.org,
        robert@nanguo.chalmers.com.au, freebsd-questions@freebsd.org,
        freebsd-isp@freebsd.org, hackers@freebsd.org
Subject: Re: progress report on connection problems 
In-reply-to: Your message of "Wed, 29 Jan 1997 09:13:31 +1030."
             <199701282243.JAA13081@genesis.atrad.adelaide.edu.au> 
From: David Greenman <dg@root.com>
Reply-To: dg@root.com
Date: Tue, 28 Jan 1997 15:48:18 -0800
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>Steve stands accused of saying:
>> > 
>> > 1)	Contact the vendor for a fix; one probably exists.
>> > 
>> > 2)	If no fix is available, turn extension off on the FreeBSD
>> > 	system, and submit a bug report to the vendor so that a
>> > 	fix will happen.
>> 
>> Turning extensions off does not stop the problem.
>
>Ah, but it does.  It's just that other FreeBSD systems (like Yahoo) still
>have them turned on, so the Annex is dropping its guts regardless.
>
>As has been mentioned, the _correct_ response is to tell your provider
>that their Annex is _BROKEN_, and that they need to upgrade its
>software (which I believe is a free exercise, but you can ransack
>Xylogics' website for details there) preferably before you take your
>business elsewhere.

   The traces that have been posted don't show that as being the problem. TCP
extensions cause problems at connection startup and the traces are showing
that a regular data packet is being dropped. One possible reason that this
problem is being noticed when FreeBSD machines are involved might be due
to FreeBSD's Path MTU Discovery causing the packets to be large. It seems
likely to me that the Annex can't deal with large packets some or all of the
time and drops the packet rather than fragmenting and/or without sending the
proper ICMP message (which would break MTU discovery).

-DG

David Greenman
Core-team/Principal Architect, The FreeBSD Project