Multicast applications over IP are becoming popular. Linking multicast sources and receivers over a wide area network has become a reality. Multicast source discovery protocol (MSDP), along with sparse mode version of Protocol Independent Multicast (PIM-SM) has been instrumental in achieving this inter-domain multicast routing. MSDP model periodically exchanges multicast source active information across the multicast domains based on flooding technique. This mechanism has intrinsic problems of flooding, high bandwidth consumption at the core of the Internet and subjects the routers to unnecessary computation. As a long term solution, Border Gateway Multicast Protocol (BGMP) has been proposed earlier. This protocol is not yet ready for deployment. Whereas, MSDP model is based on existing functional protocols and widely deployed in the Internet. Hence improving scalability and performance in the current version of MSDP is of utmost importance. In this thesis we study the problems with the existing protocol (MSDP) and propose an efficient model called "efficient MSDP or EMSDP". Our approach is based on an incremental source active updates and explicit withdraw techniques. EMSDP solves the above-mentioned problems and improve the performance to a great extent. Analysis of results and comparison with the existing model will be made to demonstrate the effectiveness of our approach.