5. Conclusions and outlook

To cope with the emergence of multicast applications with high bandwidth, availability and tunneling constraints, the IETF has been working for the past 5 years to extend MPLS technology, initially defined ten years ago for transporting unicast traffic, to ensure efficient transport of multicast traffic in an MPLS network. The resulting MPLS multicast architecture enables the transport of IP multicast, IP VPN multicast and Layer 2 VPN multicast traffic (Ethernet, ATM, TDM). It defines LSPs with one source and several destinations, known as point-to-multipoint LSPs (P2MP) or MPLS trees. The RSVP-TE and LDP protocols have been extended to establish MPLS trees. These extensions are called MLDP and P2MP RSVP-TE respectively.

MLDP enables the establishment of leaf-initiated MPLS shortest-path trees. It scales very well, but does not offer traffic engineering or fast...