Hi Hugo,

Since OpenDaylight has atleast 3 Neutron based south-bounds (OVSDB, OpenDove & VTN), we centralized the Neutron NB-API
on the controller project. And each of the above 3 south-bound plugin provides common services for handling Network, Subnet and Port events.
You can see all of these under the controller projects :
-> networkconfig.neutron
-> networkconfig.neutron.implementation
-> networkconfig.neutron.northbound

On the OVSDB side, Please take a look @
-> ovsdb.neutron

- NetworkHandler (handles Network creation events)
- PortHandler (VM / Port creation events).

Now, which hypervisors are part of the tenant network is something that can derive out of the above 2 events and the
centralized cache maintained in the networkconfig.neutron plugin.

BTW, I dont like to maintain caches in OVSDB unless it is strictly necessary (fearing the caches going out-of-sync and chasing those problems are nightmare).
So, I depend on events and dont mind CPU cycles to form the picture every time an event happens.
So, we dont have a DB, that will give the info on all the hypervisors that are part of a tenant network.
All you get is all the Ports belong to a Network. From the Neutron Port and the OVSDB Port database, we can derive the
exact set of hypervisors / nodes that make a given tenant network.

Thanks,
Madhu