BGP Transport VPNs

This document specifies a mechanism, referred to as "service mapping", to express association of overlay routes with underlay routes using BGP. The document describes a framework for service mapping, and specifies BGP protocol procedures that enable dissimination of the service mapping information that may span across administrative domains. It makes it possible to advertise multiple tunnels to the same destination. A new BGP transport address family is defined for this purpose that uses BGP-VPN [RFC4364] technology and follows MPLS- BGP [RFC8277] NLRI encoding. This new address family is called "Transport-VPN".