This paper proposes DINloop (Data-In-Network loop) based multicast with GMPLS (generalized multiprotocol label switching) to overcome the scalability problems existing in current inter-domain multicast protocols. In our approach, multiple multicast sessions share a single DINloop instead of constructing individual multicast trees. DINloop is a special path formed using GMPLS to establish LSPs (Label Switched Paths) between DIN Nodes, which are core routers that connect to each intra-domain. We adopt link bundling method to use fewer labels. Packet Processing Module analyzes the coming multicast message and GMPLS Manager assigns a label to it. Then the multicast packet is fast forwarded using label. Simulations show that DINloopbased multicast uses the smallest message number needed to form the multicast structure compared with conventional inter-domain multicast protocols. In addition, the routing table size in core routers does not increase as the number of multicast group increases, ...