The following diagram demonstrates how the Neutron API service interacts with the various plugins and agents responsible for constructing the virtual and physical network at a high level:
The preceding diagram demonstrates the interaction between the Neutron API, Neutron plugins and drivers, and services such as the L2 and L3 agents. For more information on the Neutron ML2 plugin architecture, please refer to the following URL: https://docs.openstack.org/neutron/pike/admin/config-ml2.html