From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jay Vosburgh Subject: Re: balance-alb and arp-reply stomping Date: Tue, 08 Jan 2013 09:14:39 -0800 Message-ID: <31979.1357665279@death.nxdomain> References: Cc: netdev@vger.kernel.org To: "Matthew O'Connor" Return-path: Received: from e34.co.us.ibm.com ([32.97.110.152]:42126 "EHLO e34.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756231Ab3AHRPQ (ORCPT ); Tue, 8 Jan 2013 12:15:16 -0500 Received: from /spool/local by e34.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 8 Jan 2013 10:15:15 -0700 Received: from d03relay05.boulder.ibm.com (d03relay05.boulder.ibm.com [9.17.195.107]) by d03dlp03.boulder.ibm.com (Postfix) with ESMTP id 821F719D805F for ; Tue, 8 Jan 2013 10:15:08 -0700 (MST) Received: from d03av06.boulder.ibm.com (d03av06.boulder.ibm.com [9.17.195.245]) by d03relay05.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r08HEl4K077782 for ; Tue, 8 Jan 2013 10:14:55 -0700 Received: from d03av06.boulder.ibm.com (loopback [127.0.0.1]) by d03av06.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id r08HGtGq029696 for ; Tue, 8 Jan 2013 10:16:56 -0700 In-reply-to: Sender: netdev-owner@vger.kernel.org List-ID: Matthew O'Connor wrote: >Hi! I've encountered what appears to be a known "issue" with >balance-alb, whereby when a bond configured thus is put into a bridge >with virtual ethernet adapters, on reply to arp requests the bond >appears to "stomp" the MAC of the outgoing replies with one of its own >adapters' MACs. The consequence seems to be intermittent >connectivity, easily witnessed by ping-loss early in a virtual >adapter's life. Checking the ARP cache on another machine shows that >the virtual adapter's MAC has been replaced with one of the bond >slaves'. Other bonding modes do not exhibit this behavior. > >I was wondering if this is something that had been brought up before >for fixing, and whether or not you would accept a patch if an >appropriate fix was implemented? My naive understanding would suggest >checking the outgoing reply against a table of known slaves, and if >the MAC did not exist there then map it to a slave and transmit the >reply unmodified. This should be fixed in current kernels (to have balanace-alb mode not modify ARPs that do not originate locally); I see the patch in the 3.8-rc2 source, but not in the linux-3.7.1 source. You could apply the patch to an older kernel, it's pretty simple. The patch itself can be found here: http://git.kernel.org/?p=linux/kernel/git/stable/linux-stable.git;a=patch;h=567b871e503316b0927e54a3d7c86d50b722d955 -J --- -Jay Vosburgh, IBM Linux Technology Center, fubar@us.ibm.com