From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarek Poplawski Subject: Re: LRO/GSO interaction when packets are forwarded Date: Wed, 23 Apr 2008 10:38:10 +0000 Message-ID: <20080423103809.GB3994@ff.dom.local> References: <20080422160130.0b84959a@speedy> <20080423060018.GA3946@ff.dom.local> <20080423061538.GB3946@ff.dom.local> <20080423100702.GS21637@solarflare.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Stephen Hemminger , Kieran Mansley , Stephen Hemminger , netdev@vger.kernel.org To: Ben Hutchings Return-path: Received: from nf-out-0910.google.com ([64.233.182.184]:22184 "EHLO nf-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751884AbYDWKfT (ORCPT ); Wed, 23 Apr 2008 06:35:19 -0400 Received: by nf-out-0910.google.com with SMTP id g13so967089nfb.21 for ; Wed, 23 Apr 2008 03:35:17 -0700 (PDT) Content-Disposition: inline In-Reply-To: <20080423100702.GS21637@solarflare.com> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, Apr 23, 2008 at 11:07:04AM +0100, Ben Hutchings wrote: > Jarek Poplawski wrote: > > On Wed, Apr 23, 2008 at 06:00:18AM +0000, Jarek Poplawski wrote: > > > On 23-04-2008 01:01, Stephen Hemminger wrote: > > > ... > > > >>>> First off, no hardware should ever do LRO on non-local packets. If the > > > >>>> hardware isn't smart enough to do this, I guess the bridge code to have > > > >>>> an API to turn it off. IP should also turn it off if ip_forwarding > > > >>>> is enabled on that device. > > > > > > Could you explain this more? (I can't see any obvious reason why > > > forwarding between local networks should differ here from bridging?) > > > > ...and the second question: is only ip_forwarding flag checking right > > way to disable something destined for local packets? > > "Non-local" here simply means destined for another host. It doesn't > matter whether that host is on the same LAN or not. Thanks for explanation! I'd still like to know why it's wrong, and why we should turn this off on a device with ip_forwarding enabled without checking how smart this hardware is? Regards, Jarek P.