Comment 2 for bug 1523398

The problem would arise in the following sequence:
- network A is not associated with any BGPVPN
- port is created on network A
- (the bagpipe BGPVPN driver does nothing, the agent does nothing related to BGPVPNs)
- network A is associated to a BGPVPN
- the driver sends a 'create_bgpvpn' RPC, informing all agents that network A has new RT import/exports for IPVPNs
- the agents would like to plug the port in a VRF, but will miss base network information (network_id, mac_address, ip_address, gateway_ip)
- FAIL

The network_id, mac_address and ip_address could be retrieved by the agent from get_device_details, but we would still miss gateway_ip. Sending everything in the BGPVPN RPC allows to avoid making too many RPCs.