The pre_live_migration() method calls setup_networks_on_host() in nova's internal network api. It is the version of that method in the api specialised for neutron that is empty. The nova network version of that method does something.
We need to populate setup_networks_on_host() with code that will call neutron. That method is in the file: nova/network/neutronv2/api.py
Oops, correction to above comment:
The pre_live_ migration( ) method calls setup_networks_ on_host( ) in nova's internal network api. It is the version of that method in the api specialised for neutron that is empty. The nova network version of that method does something.
We need to populate setup_networks_ on_host( ) with code that will call neutron. That method is in the file: nova/network/ neutronv2/ api.py