From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: Bridge stays down until a port is added Date: Mon, 26 Sep 2011 17:43:19 -0700 Message-ID: <20110926174319.0fa59e1f@nehalam.linuxnetplumber.net> References: <20110811070659.GA21307@torres.zugschlus.de> <20110811081706.7307e8b2@nehalam.ftrdhcpuser.net> <20110917204257.GA2636@torres.zugschlus.de> <1316550027.1783.102.camel@dcbw.foobar.com> <20110925082504.GA32712@torres.zugschlus.de> <20110926084743.35cb2ccc@nehalam.linuxnetplumber.net> <4E80DA4D.3090404@gmail.com> <20110926130507.1435d76b@nehalam.linuxnetplumber.net> <4E80F8BD.4010401@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Nicolas de =?ISO-8859-1?B?UGVzbG/8YW4=?= , Marc Haber , netdev@vger.kernel.org To: Sven-Haegar Koch Return-path: Received: from mail.vyatta.com ([76.74.103.46]:44464 "EHLO mail.vyatta.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750788Ab1I0AnW convert rfc822-to-8bit (ORCPT ); Mon, 26 Sep 2011 20:43:22 -0400 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Tue, 27 Sep 2011 02:28:42 +0200 (CEST) Sven-Haegar Koch wrote: > On Tue, 27 Sep 2011, Nicolas de Peslo=FCan wrote: >=20 > > Le 26/09/2011 22:05, Stephen Hemminger a =E9crit : > > > On Mon, 26 Sep 2011 22:02:21 +0200 > > > Nicolas de Peslo=FCan wrote: > > [...] > > > > Stephen, > > > >=20 > > > > What do you think about a generic per-interface option that wou= ld cause > > > > bind() to accept tentative > > > > address hold by a particular interface? This of course violate = IPv6 > > > > principle, but we are talking > > > > about interfaces that are unable to do DAD, either permanently = or until > > > > something happens on the > > > > underlying device. > > > >=20 > > > > echo 1> /sys/class/net/br0/allow_bind_on_tentative_address > > > > echo 1> /sys/class/net/dummy0/allow_bind_on_tentative_address > > > > echo 1> /sys/class/net/wlan0/allow_bind_on_tentative_address > > > > and so on... > > > >=20 > > > > And we may possibly automatically reset this option to 0 if DAD= eventually > > > > causes the address to be > > > > considered duplicate. > > >=20 > > > The issue is that if DAD rejects a duplicate, the socket is dead = and > > > application is > > > out of luck. > >=20 > > Yes, and this is by design. Setting the option would state "I want = to allow > > early bind(), prior to DAD and I assume the fact that a possible du= plicate > > address will cause the corresponding socket to be dead and so the u= sing > > application." >=20 > How about a setting just completely disabling this=20 > duplicate-address-detection crap? > Already multiple ways to disable it: 1. Set /proc/sys/net/ipv6/XXX/accept_dad to 0 2. Set flag when assigning address with 'ip add add ... nodad'=20 3. Set IFF_NOARP on the interface (done by drivers)