From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jay Vosburgh Subject: Re: Bonding ALB sends bogus packets Date: Thu, 30 Jul 2009 13:28:19 -0700 Message-ID: <22132.1248985699@death.nxdomain.ibm.com> References: <20090730130656.680e9152@nehalam> Cc: Ben Greear , bonding-devel@lists.sf.net, netdev@vger.kernel.org To: Stephen Hemminger Return-path: Received: from e33.co.us.ibm.com ([32.97.110.151]:52119 "EHLO e33.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752635AbZG3U2V (ORCPT ); Thu, 30 Jul 2009 16:28:21 -0400 Received: from d03relay02.boulder.ibm.com (d03relay02.boulder.ibm.com [9.17.195.227]) by e33.co.us.ibm.com (8.14.3/8.13.1) with ESMTP id n6UKQXf2015350 for ; Thu, 30 Jul 2009 14:26:33 -0600 Received: from d03av03.boulder.ibm.com (d03av03.boulder.ibm.com [9.17.195.169]) by d03relay02.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id n6UKSKQa128638 for ; Thu, 30 Jul 2009 14:28:20 -0600 Received: from d03av03.boulder.ibm.com (loopback [127.0.0.1]) by d03av03.boulder.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id n6UKSHWx028550 for ; Thu, 30 Jul 2009 14:28:20 -0600 In-reply-to: <20090730130656.680e9152@nehalam> Sender: netdev-owner@vger.kernel.org List-ID: Stephen Hemminger wrote: >The bonding ALB mode builds packets with type, ETH_P_LOOP. > >Well ETH_P_LOOP is defined as 0x0060 which looks completely bogus. >All Ethernet types less than 1536 are interpreted as 802.2 frames. >The result is that the resulting packet looks like a bogus 802.2 >frame to the other host (or switch). I have no idea what the >initial design was or what the purpose of this code is, but it >should either send a real packet or nothing at all. I've looked at that code before, too, although I hadn't noticed that ETH_P_LOOP is under the limit for interpretation as a length instead of a type. I believe the purpose of the code is to update the switch's MAC address table for the port and insure it's correct, since the alb mode can move MAC addresses around amongst the set of slaves. -J --- -Jay Vosburgh, IBM Linux Technology Center, fubar@us.ibm.com