What if I had two IPv6-capable ISPs for my home, and a /64 or a /56 from each of them? Is it possible to setup a backup link this way?
I know that my home router can advertise multiple global IPv6 prefixes into the LAN, but how will LAN hosts failover to the backup gateway if the primary ISP fails? They will have IPv6 addresses from both blocks, which should they choose for their outgoing src address?
With two IPv4 ISPs and NAT, the setup is rather trivial, outgoing connections will work via either of the ISPs because the hosts needn't be aware of the failure, and their src private IP is always the same.