From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Sylvain Coutant" Subject: RE: Ethernet MTU Date: Wed, 16 Aug 2006 14:30:59 +0200 Message-ID: <00d401c6c12f$d53b8830$2f00a8c0@ELTON> References: <20060816121256.GR27734@skywalker.creative.net.au> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <20060816121256.GR27734@skywalker.creative.net.au> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: 'Adrian Chadd' Cc: 'xen-devel' List-Id: xen-devel@lists.xenproject.org > > Is there any plan to raise supported ethernet mtu above 1500 ? > Currently, packets are dropped above this point (tested against = xen-3.0.2- > testing). Even 802.1q tags require explicitly lowering the mtu to 1496 = to > work. >=20 > Keeping this -just- on xen-devel - >=20 > Which interface are you talking about being > 1500 bytes? My primary point is to support jumbo frames (9000 bytes mtu). My second = point is to trunk domU to an external switch. 1/ I am able to set up a linux bridge with 9000 bytes mtu without = trouble as long as it does not involve any Xen interface. And unable to = set the mtu on vifs to something larger than 1500 bytes. I would like to = configure my vifs to be compliant in mtu with the Ethernet network they = are connected to which is full jumbo. 2/ I tried several scenario such as managing tags in dom0's (and setup = as many bridges as vlans) or trunking vlan frames to domUs. In this = later case, I need to bring down the mtu to 1496 for the frames to be = forwarded across the bridge. Whatever code is rejecting the frames, it = could be avoided if Xen's vifs were able to support larger mtus.=20 BR, -- Sylvain COUTANT