From: Dan Siemon <dan@coverfire.com>
To: netdev@vger.kernel.org
Subject: PMTU problem with >2.6.38 and IPIP tunnels
Date: Sat, 23 Jul 2011 21:40:49 -0400 [thread overview]
Message-ID: <1311471668.10268.12.camel@ganymede> (raw)
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I'm running into some MTU related problems with kernels newer than
2.6.38. I've tried bisecting and it appears the problem was introduced
between 2.6.39rc2 and rc3 but I'm not 100% certain because the problem
does not always present itself immediately. I am certain this does not
occur with 2.6.38.8.
I tunnel all of my home network traffic over an IPIP tunnel. My Internet
access is DSL based so there's a PPPoE connection as well. Both ends of
the IPIP tunnel are Linux.
When the gateway is first booted with the problem kernel everything is
fine. Using 'show ip route cache' I see MTU entries with the correct
values. After a short period the MTU on all the routes starts dropping
in what often appears to be 20 byte increments.
show ip route cache | egrep -i mtu
cache <src-direct> expires 435sec ipid 0x28de mtu 712 iif eth1
cache <src-direct> expires 542sec ipid 0x66e8 mtu 672 iif eth1
Until eventually all routes show a MTU of 552.
I'd be happy to run tests if anyone has an idea of what is causing this.
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reply other threads:[~2011-07-24 2:43 UTC|newest]
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