Re: [2.6.0-test1-mm1] TCP connections over ipsec hang after a few seconds

From: Sean Neakums (
Date: Sun Jul 20 2003 - 07:29:24 EST

James Morris <> writes:

> On Sat, 19 Jul 2003, Sean Neakums wrote:
>> twenty. The problem seems unrelated to the amount of data
>> transferred; I've tried both bulk rsync transfers and ssh sessions.
>> I've also tested the same boxes over 100baseT; still happens.
> It sounds a bit like a pmtu problem related to the wireless bridge, but
> that would be dependent on amount of data transferred and should not
> happen on 100baseT.

I am seeing a lot of "pmtu discvovery on SA AH/03537192/c0a80003" type
messages (I forgot to check for them when on 100baseT; will recheck
that). Are these indicative of such a problem? I seem to recall that
reducing the max MTU is not as straightforward as just adjusting the
interfaces' mtu setting. What should I do to eliminate pmtu as the
source of the problem?

> Transport mode (just blowfish encryption) looks to be working ok for me,
> I'm able to ftp uncompressed kernel tarballs between two boxes over
> gigabit ethernet with no apparent problems.

I had been using 3des with AH; just retried with blowfish 448 and no
AH with much the same result.

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