In recent IP/MPLS network

the LSPs set up through RSVP-TE can guarantee the quality of paths.However

this kind of LSP is point-to-point（P2P）

which has low efficency while transporting data to multi-user.The RSVP- TE P2MP technique combines the MPLS traffic engineering and broadcast

choosing branch LSR to copy the traffic

guaranteeing the quality of transport

and lowering whose cost.This article introduces the principle and key technique of MPLS P2MP.