Do I need Controllers and Neutron nodes to send requests on a bare metal machine in OpenStack? Can we send requests directly on a bare metal machine without passing them through controller/neutron nodes?
Provider networking allows you to attach Nova instances directly to existing layer 2 networks so that they do not need to transit the Neutron controller for either local or external network access. You can mix-and-match provider networks with normal OpenStack virtual networks depending on your needs and available network resources.
This same solution would allow baremetal machines to communicate without involving the Neutron host.