The Research And Design On Interactive Tele-Lecturing System Based On Multicast Agent

As the key component of E-Learning, the live teaching system is applied more and more extensively. Currently, IP multicast is the dominative mode in multimedia data transmission. Due to the deployment difficulties of IP multicast, it is necessary to find out a novel transmission mechanism.Breaking the restriction for network hardware, the application level multicast technology makes it possible in the large-scale deployment in wide area network, in which multicast are realized across application layer. But the application level multicast has disadvantages at delay and resource usage.This paper proposes a multicast agent mechanism without reworking quondam application systems over existing network. Considering that wide area network in teaching system is composed of local area networks, it is to deploy inner IP multicast in local ones which support IP multicast, and the multicast islands are connected by agents. Also the agents are fit for those local networks in which IP multicast is non-supported. Multicast agent servers are deployed the edge of multicast islands. For sending, inner multicast signals are transferred outer single signals. And for receiving, contrary processes are executed. All of agents build up a whole network to support live teaching system. Prevented from modifying source code, the old systems can be expediently scalable deployed in wide area network without the limit of hardware.The ITL system based on multicast agent is testified feasible to realize application level multicast. But there needs extra machine and circumscribes within multicast islands. All the same, the flexible multicast agent mechanism would be increasingly applied for its predominance to keep old systems from changing enormously.