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Multicast is an efficient mechanism for delivering data to multiple receivers. However conventional multicast routing suffers from a linear scalability problem that impedes the deployment of IP multicast in the Internet. The number of forwarding states maintained in the network layer increases linearly with the number of existing multicast channels in the network. MPLS coexists with many existing network protocols and can provide scalability for how these protocols are used in today's networks. In this paper, we propose a new scalable multicast solution in MPLS networks to reduce the number of forwarding states in the network layer. In previously existing solutions, forwarding states are removed from non-branching routers on multicast trees and packets are label switched by MPLS LSPs in non-branching routers. Our new solution proposes a new algorithm for multicast tree construction and a new channel sharing scheme to further reduce the number of forwarding states in branching routers. Simulation results show that the new solution can achieve 85%-97% reduction in the number of multicast forwarding states in MPLS networks over network layer multicast schemes, and 45%-90% reduction over the existing MPLS multicast tree based multicast.