[libvirt] IPv6 subnet on virbr0

[Daniel P. Berrange]

On Fri, Jun 05, 2009 at 02:29:24PM +0200, Bernie Innocenti wrote:
> On 06/05/09 12:43, Daniel P. Berrange wrote:
> > I'm not sure that we should automatically run radvd, because this has
> > potential implications for the host as a whole. It is hard to restrict
> > scope to just the virbr0 interface, as we do with IPv4 using NAT.
> 
> We could run a separate instance of radvd using a custom configuration
> file (-C option), limiting it to the bridge interface, like so:

Oh sure, what I meant was that simply running radvd & setting an
IPv6 addr on virbr0 isn't sufficient in all case. You need to turn
on IPv6  forwarding, but you can't do this if the primary LAN interfaces
are using IPv6 auto-config.  So in most 'out of the box' scenarios
you won't be able to get routable IPv6 configs working on virbr0. It'll
only work if the admin has configured their host with non-autoconf
addresses and enabled forwarding. 

> 
> interface virbr0
> {
> 	IgnoreIfMissing on;
> 	AdvSendAdvert on;
> 	MinRtrAdvInterval 30;
> 	MaxRtrAdvInterval 100;
> 	AdvDefaultPreference low;
> 	AdvHomeAgentFlag off;
> 
> 	#bernie: we actually have a /48, thus 65536 /64 subnets
> 	prefix 2001:4978:243:1::0/64
> 	{
> 		AdvOnLink on;
> 		AdvAutonomous on;
> 	};
> };


Regards,
Daniel
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