From: jamal <hadi@cyberus.ca>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: netdev@vger.kernel.org, bugzilla-daemon@bugzilla.kernel.org,
bugme-daemon@bugzilla.kernel.org, benoit.papillault@free.fr
Subject: Re: [Bugme-new] [Bug 14837] New: gretap does not fragment IP packets
Date: Sat, 19 Dec 2009 07:55:03 -0500 [thread overview]
Message-ID: <1261227303.11973.2.camel@bigi> (raw)
In-Reply-To: <20091218153209.45042a58.akpm@linux-foundation.org>
On Fri, 2009-12-18 at 15:32 -0800, Andrew Morton wrote:
> (switched to email. Please respond via emailed reply-to-all, not via the
> bugzilla web interface).
>
> On Fri, 18 Dec 2009 23:10:01 GMT
> bugzilla-daemon@bugzilla.kernel.org wrote:
>
> > http://bugzilla.kernel.org/show_bug.cgi?id=14837
> >
> > Summary: gretap does not fragment IP packets
> > Product: Networking
> > Version: 2.5
> > Kernel Version: 2.6.32
> > Platform: All
> > OS/Version: Linux
> > Tree: Mainline
> > Status: NEW
> > Severity: normal
> > Priority: P1
> > Component: IPV4
> > AssignedTo: shemminger@linux-foundation.org
> > ReportedBy: benoit.papillault@free.fr
> > Regression: No
> >
> >
> > When gretap is used to encapsulate Ethernet packets into IP packets, the
> > encapsulated IP packets are larger than the original Ethernet packet, as
> > expected.
> >
> > Let's say you create a gre0 interface with a 1500 bytes MTU (since this
> > interface will latter be inserted in a bridge interface, its MTU must be 1500).
> > And Let's say the GRE encapsulated packet (now larger than 1500 bytes) is going
> > to be routed over an IP interface with a 1500 bytes MTU.
> >
> > The expected behavior would be that the encapsulated packet be fragmented. The
> > observed behavior is that any encapsulated packets over 1500 bytes are simply
> > dropped and an ICMP "fragmentation needed" message is sent to ... who knows.
Sending back an ICMP is good behavior. Sending it "who knows" is not ;->
Make sure it is sent to the originator of the packet. The originator of
the packet should play nice and reduce the path mtu.
One work around is to reduce the gre device mtu to something less than
1500B.
cheers,
jamal
next prev parent reply other threads:[~2009-12-19 12:55 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <bug-14837-10286@http.bugzilla.kernel.org/>
2009-12-18 23:32 ` [Bugme-new] [Bug 14837] New: gretap does not fragment IP packets Andrew Morton
2009-12-18 23:47 ` Stephen Hemminger
2009-12-19 12:55 ` jamal [this message]
2009-12-21 1:17 ` Benoit PAPILLAULT
2009-12-21 19:09 ` jamal
2010-01-07 14:30 ` Benoit PAPILLAULT
2010-01-10 16:03 ` jamal
2010-01-10 17:43 ` Benoit PAPILLAULT
2010-01-10 21:59 ` Herbert Xu
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