[radvd-devel-l] Advertise Alternate link local address

[Seth Mos]

Hello,

I am a developer on the pfSense open source firewall based on FreeBSD 
and I need some help with radvd.

In pfSense one can use CARP for high availability so that failure of one 
machine does not result in interruption of service.

This means that there is a shared IPv6 address on the firewalls, just 
like IPv4 and I need to advertise this address to the clients.

That means I need to modify radvd to advertise the CARP link local and 
global address to the clients so the failover is seemless (< 2 seconds 
generally) and all tcp sessions survive.

Because of the nature of the CARP interface in FreeBSD I'm not able to 
run the radvd process on the CARP virtual IP interface as it can not 
currently participate in multicast groups.

That leaves me with the other option, which is run it on the parent 
interface, but advertise the CARP link local and global.

If one can give me some pointers on where to modify radvd for this 
purpose I would appreciate that.

Kind regards,

Seth Mos
pfSense developer