is there any sdn solution for openstack multi site sdn ?

I read something about network to network api extension for neutron presented in an openstack summit but it seems no more adopted.

Any help, please?

We have 3 separated openstack installations and I wonder if there is some solution for controlling network (vxlan to vxlan connection, sec groups airchestration and so on)

Openstack cascading seems only a dream.

Ignazio