Comment 27 for bug 1302080

Tore, I think I've found the code path, perhaps you could confirm based on the debug messages in your log files.

The nova vif driver (nova/virt/libvirt/vif.py) plug_bridge() method will be called, which will ensure the bridge exists. For this it will call over to ensure_bridge() in nova/network/linux_net.py. That code does not disable ipv6 :(

The hybrid case used when OVS is the bridge calls plug_ovs_hybrid(), which uses the code that was added to disable ipv6.

That's my guess without actually setting it up, so might just be a one-line change?