Comment 2 for bug 1663317

All the discussion can be found in https://bugs.launchpad.net/neutron/+bug/1302080

Basically, it was possible to reach from a guest perspective the hypervisor in case the bridge was also IPv6. The solution was rather to stop using IPv6 for that bridge automatically.

That doesn't mean that you can't use IPv6 IMHO, just that the bridge won't use it automatically.

Anyway, the above bug report I provided to you seems the best for discussing about your problem, I'd like to put this one as Opinion as I'm not sure Nova can help here.