Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756482AbZCEXAJ (ORCPT ); Thu, 5 Mar 2009 18:00:09 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755418AbZCEW7x (ORCPT ); Thu, 5 Mar 2009 17:59:53 -0500 Received: from mx1.aecom.yu.edu ([129.98.1.51]:52715 "EHLO mx1.aecom.yu.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755265AbZCEW7w (ORCPT ); Thu, 5 Mar 2009 17:59:52 -0500 X-AuditID: 816201a0-a8de3bb000001567-0c-49b05966f8fa Mime-Version: 1.0 Message-Id: In-Reply-To: References: Date: Thu, 5 Mar 2009 17:58:59 -0500 To: "Brandeburg, Jesse" , "linux-kernel@vger.kernel.org" From: Maurice Volaski Subject: RE: e1000 is subtly incompatible with jumbo frames Cc: "Kirsher, Jeffrey T" Content-Type: text/plain; charset="us-ascii" ; format="flowed" X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1707 Lines: 36 At 2:38 PM -0800 3/5/09, Brandeburg, Jesse wrote: >Maurice Volaski wrote: >> I have a system using the e1000 driver with the MTU set to 9000. If I >> try FTP to get a file, the transfer does not start. Something about >> the 9000 MTU is preventing the NIC from receiving packets back from >> the FTP server. (The FTP server is on the same subnet and its NIC >> also has MTU 9000.) The 9000 MTU NIC works fine in every other >> respect, even allowing me to access the system via ssh. When I change >> the MTU to 1500, then FTP works fine. The problem is common to >> numerous kernel versions including 2.6.24 through 2.6.29-rc5. > >This sounds like you have not configured the MTU the same on both ends >or some station in between is having issues with the large packets > >please double check your configuration. > Oh, sorry to trouble you, but I got tricked. I've been testing systems under VMWare Fusion on my Mac and it doesn't support jumbo frames. I got tricked because the identical OS running on real hardware was behaving identically, but the new switch it's connecting to had jumbo frames turned off, so naturally it shows the same problem. With jumbo frames turned on, it's now transferring fine. At least anyone now if anyone else has an odd problem with FTP, they'll know to what to check. -- Maurice Volaski, mvolaski@aecom.yu.edu Computing Support, Rose F. Kennedy Center Albert Einstein College of Medicine of Yeshiva University -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/