Comment 17 for bug 1953165

Clearly my suspicion in comment #4 was wrong. But because of that, this issue fell off my radar. Sorry for that.

I'm looking to reproduce the side/followup effect mentioned by Kamil in comment #6 in my dev environment. But until I can do that, if you can, please tell me, for this side effect to happen:

1) How many dhcp-agents do you have?
2) What dhcp_agents_per_network setting do you use?

My current thinking goes:
If we have only one agent scheduled to a network, then we cannot have DAD failures.
If we have more than one agent scheduled to a network, then (at least initially) one will work okay and the rest will have DAD failures and because of that will have the followup problems too.

But this means we should only lose the redundancy of dhcp, not dhcp service itself. Of course I can imagine situations in which this leads to loss of dhcp later: for example having two agents, initially one okay, one with the DAD failure and after turning off the okay one, the other cannot recover and produce a successful failover.

But I'd like really to understand in which ways (maybe multiple) we may get to losing all dhcp.

Regarding workarounds mentioned:

* enable_isolated_metadata=False should be safe if you can live with l3-agent's metadata
* net.ipv6.conf.all.disable_ipv6=1 should be safe if you can live without ipv6