Juniper Networks Cisco Systems Cisco Systems Huawei Technologies Alcatel-Lucent Ericsson The Multicast Virtual Private Network (MVPN) specifications require the use of multicast tunnels ("P-tunnels") that traverse a Service Provider's backbone network. The P-tunnels are used for carrying multicast traffic across the backbone. A variety of P-tunnel types are supported. Bit Index Explicit Replication (BIER) is a new architecture that provides optimal multicast forwarding through a "multicast domain", without requiring intermediate routers to maintain any per-flow state or to engage in an explicit tree-building protocol. This document specifies the protocol and procedures that allow MVPN to use BIER as the method of carrying multicast traffic over an SP backbone network.