From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan-Bernd Themann Subject: LRO with ip fragmentation Date: Tue, 11 Nov 2008 17:13:18 +0100 Message-ID: <4919AF1E.5060500@de.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit To: netdev@vger.kernel.org, Christoph Raisch , jb.billaud@gmail.com Return-path: Received: from mtagate6.uk.ibm.com ([195.212.29.139]:47113 "EHLO mtagate6.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751530AbYKKQNV (ORCPT ); Tue, 11 Nov 2008 11:13:21 -0500 Received: from d06nrmr1407.portsmouth.uk.ibm.com (d06nrmr1407.portsmouth.uk.ibm.com [9.149.38.185]) by mtagate6.uk.ibm.com (8.13.8/8.13.8) with ESMTP id mABGDJhP475640 for ; Tue, 11 Nov 2008 16:13:19 GMT Received: from d06av04.portsmouth.uk.ibm.com (d06av04.portsmouth.uk.ibm.com [9.149.37.216]) by d06nrmr1407.portsmouth.uk.ibm.com (8.13.8/8.13.8/NCO v9.1) with ESMTP id mABGDJ1k4309036 for ; Tue, 11 Nov 2008 16:13:19 GMT Received: from d06av04.portsmouth.uk.ibm.com (loopback [127.0.0.1]) by d06av04.portsmouth.uk.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id mABGDJ4R022496 for ; Tue, 11 Nov 2008 16:13:19 GMT Sender: netdev-owner@vger.kernel.org List-ID: Hi, Jean-Pascal Billaud pointed us to an interesting question: Currently we do not check in the LRO receive path whether TCP packets are ip fragmented. They are aggregated in any case which might be wrong. The question is: Is it possible that we can get fragmented TCP packets without the tcp stack changing the MSS size? How can this be easily intentionally provoked for testing (only by using an extra gateway?)? Regards, Jan-Bernd