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From: kuznet@ms2.inr.ac.ru
To: davem@redhat.com (David S. Miller)
Cc: alan@lxorguk.ukuu.org.uk, roger@kea.GRace.CRi.NZ,
	linux-kernel@vger.kernel.org
Subject: Re: MTU and 2.4.x kernel
Date: Sun, 18 Feb 2001 23:17:46 +0300 (MSK)	[thread overview]
Message-ID: <200102182017.XAA28119@ms2.inr.ac.ru> (raw)
In-Reply-To: <14991.38968.898918.345197@pizda.ninka.net> from "David S. Miller" at Feb 18, 1 01:39:04 am

Hello!

> This smells bad.  Datagram protocol send sizes are only limited by
> socket buffer size, nothing more.  Fragmentation makes it work.

The thread was started from the observation that fragmented frames
do _not_ pass through router. See? 8)

Path mtu discovery exists exactly to help to solve this problem.

In this case mtu is too low to be accepted by pmtu discovery,
so that we simply disable it and start to fragment, exaclty like
pmtu discovery was disabled completely. With all the consequences.

So that workaround is not to _disable_ path mtu discovery,
but to _enforce_ it, changing thresholds.

The argument is subjectless. min_adv_mss must be changed to 256
in production version, no doubts. min_pmtu must stay at its current value
of 576. That's all.

Alexey

  reply	other threads:[~2001-02-18 20:18 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2001-02-14 20:39 MTU and 2.4.x kernel roger
2001-02-14 20:51 ` Alan Cox
2001-02-15 18:21 ` kuznet
2001-02-15 18:47   ` Alan Cox
2001-02-15 19:33     ` kuznet
2001-02-15 20:27       ` Alan Cox
2001-02-15 20:41         ` kuznet
2001-02-15 21:01           ` Alan Cox
2001-02-18 19:53             ` kuznet
2001-02-19  1:44               ` Alan Cox
2001-02-19 18:26                 ` kuznet
2001-02-19 22:20                   ` Rick Jones
2001-02-16 12:54           ` Rik van Riel
2001-02-18 11:26           ` Pierfrancesco Caci
2001-02-16 12:51       ` Rik van Riel
2001-02-18 19:55         ` kuznet
2001-02-18  9:39       ` David S. Miller
2001-02-18 20:17         ` kuznet [this message]
2001-02-18 20:32     ` kuznet
2001-02-15 20:40   ` Rick Jones
2001-02-15 20:54     ` Jordan Mendelson

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