The OpenStack Neutron Modular Layer 2 (ML2) plugin allows OpenStack Neutron to simultaneously use different Layer-2 networking technologies. The plugin currently works with industry-standard Layer-2 solutions, including OpenvSwitch (OVS), linuxbridge, and HyperV L2.
The ML2 plugin is designed as a framework to allow you to add existing and future Layer-2 networking technologies quickly and easily.For more information about the OpenStack ML2 Layer 2 plugin, refer to: https://wiki.openstack.org/wiki/Neutron/ML2