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Date:      Thu, 22 Jun 2000 21:12:08 +0300
From:      Ruslan Ermilov <ru@FreeBSD.org>
To:        net@FreeBSD.org
Subject:   [CFV] where to put TCP MSS correction code
Message-ID:  <20000622211208.A30877@sunbay.com>

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Hi!

There exists a well-known problem with broken Path MTU Discovery
(see RFC 1191) due to the buggy router software and IP firewall
misconfiguration.

See http://www.FreeBSD.org/FAQ/ppp.html#AEN3714 and
http://www.worldgate.com/~marcs/mtu/index.html for details.

Patrick Bihan-Faou <patrick@mindstep.com> found a workaround for
this problem where router "corrects" the value of TCP MSS option
so that incoming packets are guaranteed to fit in advance without
need to perform PMTU discovery cycle.

If you are interested in this stuff, please choose from one of the
following options, and reply directly to me at <ru@FreeBSD.org>.

1. This functionality should be implemented within packet aliasing
   (NAT) library, libalias(3).  This benefits from having this
   feature in both natd(8) and ppp(8).

2. This functionality is not suitable for NAT software and it should
   be implemented separately as a stand-alone daemon.
   (Already available at http://people.FreeBSD.org/~ru/tcpmssd.tgz).

3. Do both.


Thank you,
-- 
Ruslan Ermilov		Oracle Developer/DBA,
ru@sunbay.com		Sunbay Software AG,
ru@FreeBSD.org		FreeBSD committer,
+380.652.512.251	Simferopol, Ukraine

http://www.FreeBSD.org	The Power To Serve
http://www.oracle.com	Enabling The Information Age


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