From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?ISO-8859-1?Q?Nicolas_de_Peslo=FCan?= Subject: Re: IPv6: autoconfiguration and suspend/resume or link down/up Date: Sat, 23 Jul 2011 16:31:21 +0200 Message-ID: <4E2ADB39.9070409@gmail.com> References: <20110719180222.GA7509@midget.suse.cz> <20110722.010628.1678943945721626312.davem@davemloft.net> <20110722092159.GA20722@gondor.apana.org.au> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: David Miller , jbohac@suse.cz, netdev@vger.kernel.org, shemminger@vyatta.com To: Herbert Xu Return-path: Received: from mail-ww0-f44.google.com ([74.125.82.44]:41305 "EHLO mail-ww0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752871Ab1GWObZ (ORCPT ); Sat, 23 Jul 2011 10:31:25 -0400 Received: by wwe5 with SMTP id 5so2940857wwe.1 for ; Sat, 23 Jul 2011 07:31:24 -0700 (PDT) In-Reply-To: <20110722092159.GA20722@gondor.apana.org.au> Sender: netdev-owner@vger.kernel.org List-ID: Le 22/07/2011 11:21, Herbert Xu a =E9crit : > On Fri, Jul 22, 2011 at 01:06:28AM -0700, David Miller wrote: >> >> Suspend is even more important because while we were suspended we >> could be on the same network but the routers present and available >> might have changed completely. > > Unfortunately virtual machine live migration also uses the suspend > & resume mechanism. In that case we don't wish to renegotiate > everything, since the goal is to minimise the outage window. > > This would suggest that putting the policy in user-space may be the > best option. =46or the particular situation where we use suspend/resume to migrate a= virtual machine, we might have=20 a kernel parameter or sysfs entry that instruct the kernel not to reneg= otiate anything on resume. That being said, the time to renegotiate a network setup sounds very sh= ort, compared to the time for=20 a full suspend-migrate-resume cycle. I'm not sure VM migration would re= ally suffer from such=20 renegotiation. And because the local network may change while we migrate the VM (in pa= rticular if the migration=20 happens because of some failover), I think we should enforce renegotiat= ion on resume anyway. Nicolas.