From mboxrd@z Thu Jan 1 00:00:00 1970 From: jamal Subject: Re: [Bugme-new] [Bug 14837] New: gretap does not fragment IP packets Date: Mon, 21 Dec 2009 14:09:03 -0500 Message-ID: <1261422543.8201.6.camel@bigi> References: <20091218153209.45042a58.akpm@linux-foundation.org> <1261227303.11973.2.camel@bigi> <4B2ECCAB.8010702@free.fr> Reply-To: hadi@cyberus.ca Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: Andrew Morton , netdev@vger.kernel.org, bugzilla-daemon@bugzilla.kernel.org, bugme-daemon@bugzilla.kernel.org To: Benoit PAPILLAULT Return-path: Received: from mail-yx0-f187.google.com ([209.85.210.187]:54063 "EHLO mail-yx0-f187.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757056AbZLUTJH (ORCPT ); Mon, 21 Dec 2009 14:09:07 -0500 Received: by yxe17 with SMTP id 17so5144758yxe.33 for ; Mon, 21 Dec 2009 11:09:06 -0800 (PST) In-Reply-To: <4B2ECCAB.8010702@free.fr> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, 2009-12-21 at 02:17 +0100, Benoit PAPILLAULT wrote: > > > As I explained in my original message, the gre device MTU must be 1500 > bytes (since it is used in an Ethernet bridge). Ok, sorry i missed this bit. I didnt realize that the bridge device had such draconian enforcement. Bridge picks whatever the lowest common denominator is for MTU (I suspect so as to not keep track of all the interfaces; good policy, IMO, should allow a user to shoot themselves in the toe while defaulting to the min mtu). >>From the looks of it, this enforcement could be changed with a one line patch - but not being privy to the reasoning it would be unfair of me to do so from my comfortable couch. Stephen? > To reproduce the > problem, I did a very simple setup with two machines (A & B) connected > with an Ethernet cable (so no router between them). > > On machine A : > # ip link add gre0 type gretap local remote > # ifconfig gre0 mtu 1500 What i meant is try to ifconfig gre0 to something small like 1420B cheers, jamal