From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gertjan Hofman Subject: VLAN and ARP failure on tg3 drivers Date: Thu, 22 Oct 2009 21:52:42 -0700 (PDT) Message-ID: <93821.71108.qm@web32607.mail.mud.yahoo.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE To: netdev@vger.kernel.org Return-path: Received: from web32607.mail.mud.yahoo.com ([68.142.207.234]:43210 "HELO web32607.mail.mud.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751041AbZJWEwi convert rfc822-to-8bit (ORCPT ); Fri, 23 Oct 2009 00:52:38 -0400 Sender: netdev-owner@vger.kernel.org List-ID: Dear Kernel developers, A couple of weeks ago we tried to migrate from a 2.6.24=A0 kernel to a = 2.6.29 kernel and noticed our VLAN application no longer works.=A0 The = problem is easy to replicate: 1. connect 2 PC's with a cross-over cable 2. set up a fixed IP address to both PC's=A0 (say 192.168.0.[1,2]) 3. create a vlan:=A0 vconfig=A0 add eth0 0. 4. set IP addresses on the VLAN devices=A0 (say 192.168.1.[1,2]) 5. try ping one machine from the other. I tried to dig into the problem by using un-patched kernel.org kernels = with Ubuntu .config files.=A0 Kernels up to 2.6.26 work fine, kernels a= fter and including 2.6.27 fail. The problem is that ARP messages are be= ing dropped. If the ARP table is updated by hand on each machine, the c= ommunication across the VLAN works fine. At first I thought the kernel VLAN code was the problem (we had an earl= ier issue with a regression in 2.6.24) but it looks like the problem is= actually with the tg3 driver.=A0 Our system uses Broadcom ethernet chi= ps. I tried the same experiments with combination of boards that have B= roadcom and none-Broadcom and the only time I see it fail is with the t= g3=A0 driver loaded. Snooping with WireShark shows that a ARP request from the non-Broadcom = machine is seen and even answered, but never appears back on the networ= k. If the Broadcom machine orginates the ARP message, it never arrives = at the destination. I tried lowering the size of the MTU to 1492 as wel= l as giving each VLAN device a different MAC. No deal. I tried to look at tg3 patch changes from 2.6.26 to 2.6.27 but I am not= familiar enough with the Git system to extract the appropiate changes.= =A0 I am a bit surprised that I am not seeing any references to this on= the web, the combination of >2.6.27 kernels, Broadcom and VLAN cant be= that uncommon. I would be happy to provide more information and to try tests if any on= e can suggest them. Sincerely, Gertjan =20