Neutron freeze when ovn_nb_connection set to tcp 6640

[Jorge Cabello]

When ovn_nb_connection is set to port 6640 instead of 6641 on ml2_conf.ini neutron seems to start correctly but doesn't reply to any command.

The command starts but never ends waiting for neutron reply:
openstack network list --debug
...
REQ: curl -g -i -X GET http://x.x.x.x:9696 -H "Accept: application/json" -H "User-Agent: osc-lib/1.9.0 keystoneauth1/3.4.0 python-requests/2.18.4 CPython/2.7.12"
Starting new HTTP connection (1): x.x.x.x

With debug activated neutron-server.log doesn't shows any ERROR, WARNING or DEBUG but continuous INFO messages:

2018-05-24 11:41:07.973 2216775 INFO networking_ovn.ovsdb.impl_idl_ovn [-] Getting OvsdbNbOvnIdl for WorkerService with retry
2018-05-24 11:41:07.993 2216778 INFO networking_ovn.ovsdb.impl_idl_ovn [-] Getting OvsdbNbOvnIdl for OvnWorker with retry
2018-05-24 11:41:07.993 2216768 INFO networking_ovn.ovsdb.impl_idl_ovn [-] Getting OvsdbNbOvnIdl for WorkerService with retry
2018-05-24 11:41:07.995 2216769 INFO networking_ovn.ovsdb.impl_idl_ovn [-] Getting OvsdbNbOvnIdl for WorkerService with retry
2018-05-24 11:41:08.006 2216776 INFO networking_ovn.ovsdb.impl_idl_ovn [-] Getting OvsdbNbOvnIdl for RpcWorker with retry
2018-05-24 11:41:08.006 2216773 INFO networking_ovn.ovsdb.impl_idl_ovn [-] Getting OvsdbNbOvnIdl for WorkerService with retry
2018-05-24 11:41:08.021 2216777 INFO networking_ovn.ovsdb.impl_idl_ovn [-] Getting OvsdbNbOvnIdl for RpcReportsWorker with retry