We have a medium sized network with IPv4 and IPv6 across it, and our upstream provider is making IPv6 go away for two weeks while they do... something. (It's "experimental" and we don't pay for it, but it's been stable for years so we turned it on across the board.)
We have 150ish hosts on our network of at least a dozen different operating systems, plus a wireless network for people's phones and laptops, so disabling IPv6 on all our devices is a non-starter.
I would like to avoid too much of the classical broken IPv6 behaviour with long timeouts before failover to IPv4, and I am wondering what the best way of doing that is.
- Should I block outgoing IPv6 packets at the border and return an unreachable message, or will that cause hosts to be marked unreachable without falling back to IPv4?
- Is disabling AAAA resolution through our BIND nameserver feasible (and if so, how), and if so, is it sensible?
- Alternatively, will turning off RADVD do the job? We do use static configuration on some of our servers, but there's few enough of those to do them by hand.