From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ben Hutchings <bhutchings@solarflare.com>
Subject: Re: Bridge stays down until a port is added
Date: Mon, 26 Sep 2011 21:56:56 +0100
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Cc: Nicolas de =?ISO-8859-1?Q?Peslo=FCan?=
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To: Stephen Hemminger <shemminger@vyatta.com>
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On Mon, 2011-09-26 at 13:05 -0700, Stephen Hemminger wrote:
> On Mon, 26 Sep 2011 22:02:21 +0200
> Nicolas de Peslo=C3=BCan <nicolas.2p.debian@gmail.com> wrote:
[...]
> > What do you think about a generic per-interface option that would c=
ause bind() to accept tentative=20
> > address hold by a particular interface? This of course violate IPv6=
 principle, but we are talking=20
> > about interfaces that are unable to do DAD, either permanently or u=
ntil something happens on the=20
> > 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 eve=
ntually causes the address to be=20
> > considered duplicate.
>=20
> The issue is that if DAD rejects a duplicate, the socket is dead and =
application is
> out of luck.
>=20
> Has anyone looked at this issue in relation to systemd which does ear=
ly
> opportunistic binding of services?

I think it is recommended to use the IP_FREEBIND socket option.  Which
of course is not available for IPv6.

Ben.

--=20
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.