From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chuck Anderson Subject: Re: [PATCH] IPv6: DAD from bonding iface is treated as dup address from others Date: Fri, 7 Oct 2011 02:13:26 -0400 Message-ID: <20111007061326.GL23845@angus.ind.WPI.EDU> References: <1317873550-1677-1-git-send-email-Yinglin.Sun@emc.com> <20111006110047.GA22462@hmsreliant.think-freely.org> <27199.1317927933@death> <7122.1317949193@death> 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 MAIL1.WPI.EDU ([130.215.36.91]:49395 "EHLO MAIL1.WPI.EDU" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758214Ab1JGGN3 (ORCPT ); Fri, 7 Oct 2011 02:13:29 -0400 Received: from MAIL1.WPI.EDU (MAIL1.WPI.EDU [130.215.36.91]) by MAIL1.WPI.EDU (8.14.5/8.14.5) with ESMTP id p976DS2U023753 for ; Fri, 7 Oct 2011 02:13:28 -0400 Received: from SMTP.WPI.EDU (SMTP.WPI.EDU [130.215.36.186]) by MAIL1.WPI.EDU (8.14.5/8.14.5) with ESMTP id p976DSVU023750 for ; Fri, 7 Oct 2011 02:13:28 -0400 Received: from angus.ind.WPI.EDU (ANGUS.IND.WPI.EDU [130.215.130.21]) by SMTP.WPI.EDU (8.14.4/8.14.4) with ESMTP id p976DRYp020325 for ; Fri, 7 Oct 2011 02:13:27 -0400 (envelope-from cra@WPI.EDU) Received: from angus.ind.WPI.EDU (angus.ind.WPI.EDU [127.0.0.1]) by angus.ind.WPI.EDU (8.14.2/8.14.2) with ESMTP id p976DRQU001444 for ; Fri, 7 Oct 2011 02:13:27 -0400 Received: (from cra@localhost) by angus.ind.WPI.EDU (8.14.2/8.14.2/Submit) id p976DQJ9001442 for netdev@vger.kernel.org; Fri, 7 Oct 2011 02:13:26 -0400 Content-Disposition: inline In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Thu, Oct 06, 2011 at 06:24:36PM -0700, Yinglin Sun wrote: > On Thu, Oct 6, 2011 at 5:59 PM, Jay Vosburgh wrote= : > > =A0 =A0 =A0 =A0Why are you setting up the port channel after config= uring the > > bond? > > > > =A0 =A0 =A0 =A0As a possible workaround, if you have control over t= he setup > > process (perhaps it's some sort of manual process), adding one slav= e to > > the bond, leaving the other soon-to-be slaves down, then setting up= the > > switch, and finally adding the remaining slaves should work around = the > > issue, since if the bond has only one slave it won't see any looped > > packets. > > > > =A0 =A0 =A0 =A0Or you could bring the bond up as active-backup, the= n change the > > mode to balance-xor once the switch is configured. > > > > =A0 =A0 =A0 =A0Ultimately, though, the problem stems from the setti= ngs mismatch > > between the switch and the bonding system; balance-xor is meant to > > interoperate with etherchannel, and when the switch is not configur= ed > > properly, correct behavior is difficult to guarantee. > > >=20 > Jay, >=20 > Thanks a lot for the suggestion. >=20 > It's mainly about usability. We would like to provide customers with > consistent IPv6 configuration procedures as IPv4. Such workarounds > could be confusing and generate customer calls. You've created/encouraged your customers to create a broken network configuration by connecting two bonded links to a non-bonded, non-etherchannel switch port pair. This type of misconfiguration, when applied to inter-switch trunks, can cause major network issues, like looping and broadcast storms, taking down the entire network unless something like Spanning Tree is enabled to protect against such accidental loops. It should be avoided at all costs. Luckily, if the Linux host in this case is not being used as a switch/bridge, the impact of this might not be so bad--perhaps limited to the IPv6 DAD issue you report. If you want better usability and plug-n-play bonding, then require LACP/802.3ad to be used. Please don't encourage your customers to connect misconfigured devices to the network, thanks.