When you say your use case is to have broadcast/multicast communication with the instances, does that mean the vpn IP needs to be within the same L2 domain? If so, then I don't see how going through Neutron IPAM can be avoided, whether it's in a pre-reservation capacity or on-demand.
When you say your use case is to have broadcast/multicast communication with the instances, does that mean the vpn IP needs to be within the same L2 domain? If so, then I don't see how going through Neutron IPAM can be avoided, whether it's in a pre-reservation capacity or on-demand.