Connecting neutron networks with external networks at the layer-2 level

Neutron core currently has one mechanism to connect VMs in Networks to bare-metal servers in a physical L2 segment: the Provider Network extension.

This model has some limitations that were already tackled by the NVP’s Layer-2 Gateway vendor extension.

The NVP implementation has the following advantages:
1) It explicitly models the L2GW as an entity in the network. The Provider can create several L2GW objects and a Tenant can explicitly connect a network to a specific L2GW.
2) No assumption is made on the location of the external network, which may not be directly reachable from the hosts where the VMs are deployed
3) A network can be connected to multiple L2 Gateways

NVP’s Layer-2 Gateway is currently a vendor extension, the goal of this blueprint is to add a L2GW capability as a core extension.