I'm guessing you are running the "status neutron-plugin-linuxbridge-agent" on your compute node, not the controller and it is running. If that's the case and neutron agent-list isn't showing anything, it means the agent does not communicate with the controller (the process is running on your compute node but it doesn't know where to connect to the controller or another similar issue). Can you check the neutron-linuxbridge-agent logs (on the compute node) ? Can you also check if you have the correct setting in /etc/neutron/neutron.conf on the controller node (the sections [keystone_authtoken] and the rabbit or qpid settings (whichever message bus you are using) ?