A Service-Centric Multicast Architecture and Routing Protocol

In this paper, we present a new multicast architecture and the corresponding multicast routing protocol for providing efficient and flexible multicast services over the Internet. Traditional multicast protocols construct and update the multicast tree in a distributed manner, which may cause two problems: first, since each node has only local or partial information on the network topology and group membership, it is difficult to build an efficient multicast tree; second, due to lack of complete information, broadcast is often used for sending control packets and data packets, which consumes a great deal of network bandwidth. In the newly proposed multicast architecture, a few powerful routers, called m-routers, collect multicast-related information and process multicast requests based on the information collected. The m-routers handle most of multicast related tasks, while other routers in the network only need to perform minimum functions for routing. The m-routers are designed to be able to handle simultaneous many-to-many communications efficiently. The new multicast routing protocol, called the Service Centric Multicast Protocol (SCMP), builds a shared multicast tree rooted at the m-router for each group. The multicast tree is computed in the m-router by employing the Delay Constrained Dynamic Multicast (DCDM) algorithm which dynamically builds a delay constrained multicast tree and minimizes the tree cost as well. The physical construction of the multicast tree over the Internet is performed by a special type of self-routing packets in order to minimize the protocol overhead. Our simulation results on NS-2 demonstrate that the new SCMP protocol outperforms other existing protocols and is a promising alternative for providing efficient and flexible multicast services over the Internet.