The ML2plugin class creates several RPC clients during the initialization:

• For the DHCP agent, to check the status.
• The OVO changes notifier.
• The agent notifier, including the DVR RPC, the security group RPC and the tunnel RPC.

These clients are not necessary when the cluster has not Neutron RPC agents and the configuration variable ``rpc_workers`` is set to 0. In this case, all RPC connections should be avoided and none of the notification should be issued.

LP bug: https://bugs.launchpad.net/neutron/+bug/2139063