Cloned from launchpad blueprint https://blueprints.launchpad.net/neutron/+spec/gateway-api-extension.

Description:

Abstract:

Neutron already provides an abstract Router API extension for routing between cloud tenants virtual networks. Its main useful purpose is to enable NATing of IP addresses of the unlimited number of VMs to a limited pool of external/public IPv4 addresses. However, routing between virtual networks subnets adds some complexity (at least for the simple tenant abstract API) in automating the mandatory /subnet IP subnet address design of virtual networks belonging to the same tenant, in sharing various L2 services (usually by configuring helper services in routers), and in moving VMs with zero downtime (usually with extra tunneling if not in the same L2).

We propose to add optional Bridging operations to the Router object so that we abstract both Router and Bridge in a Gateway object managed by Cloud Tenants Admins. This will provide a simple REST interface to bridge virtual networks together and with physical networks while the underlying plugin will focus on programmatically controlling the L2 broadcast regardless of all the heterogeneous virtual networking technologies. This broadcast is usually emulated using L2oL3 tunnels overlays between virtual switches if native tagging is not provided, but other schemes could also be used. With this API, we will be able to easily stitch Neutron Networks to benefit from various existent services in enterprise data centers that are not managed by OpenStack:
enterprise DHCP servers, PXE boot software provisioning servers, L2VPN gateways to elastic WANs, to only cite few.

Specification URL (additional information):

https://wiki.openstack.org/wiki/Gateway