The Research Of Single-Source Multicast Based On Internet

Multicast based on Internet is facing slow development although it is a hotly debated topic since more than a decade. Lots of routers on Internet still only support unicast, which will last for many years. As a main reason that leads to this status, multicast technology should be improved. This thesis begined with the basic concepts and principles of multicast, analyzed the merits and flaws of most IP multicast routing Protocols and reliable multicast Protocols, then this thesis did some research work on single-source multicast based on Internet.This thesis brought forward a new scheme of multicast routing protocol, aiming at widely using single-source multicast on current Internet and making it more effective. In this scheme, A group is identified by unicast IP addresses and port number insteading of class D IP address, data packet is forwarded to other routers by unicast, and multicast routers forward data to members in local network by local multicast. The main advantages of this scheme are as follows. First, with unicast address, data packets can go through unicast clouds randomly, and no tunnel is demanded. Second, this identification makes the maximum number of simultaneously active multicast groups increases dramatically. Third, it constructs a shortest path tree. Not like other protocols, it can automatically reconstruct SPT when the shortest path changes and a member leaves, and no data packet is discarded or repeared in the transition.At last, this thesis advanced a reliable multicast scheme based on the new routing protocol, this thesis analyzed the reliability of multicast forwarding trees, and divided the trees into two classes-one was reliable tree and another was unreliable tree. With the two classes, different means are used to send some packets. This scheme can implement reliable multicast without buffering packets in middle nodes, and make recovering packets sent to some areas, but not to the whole group. In addition, two acknowledgement messages are used in this scheme, which makes multicast source sending packets more effectively.