The Research And Its Implement Of Simulation-Oriented Application Layer Multicast Technology

As the Internet grows up, the development of application requirements impels the production of new communication means, of which multicasting is one. At first the multicast functionality which was a basic communication means was proposed to be added to the network layer. Due to a variety of technical and non-technical reasons, the deployment of IP Multicast in Internet has been limited and sparse. Therefore some researchers in the recent past have revisited the issue whether the network layer is the best layer for implementing multicast functionality and have proposed application layer multicast (ALM) as a new approach . The basic advantage of ALM is that it requires no infrastructure support and can be easily deployed in the Internet.The paper presents a new simulation-oriented application layer multicast protocol which belongs to the mesh-first approach. By clustering technique, the protocol organizes all the end nodes into overlay with a three levels structure; Leader nodes run the link state routing algorithm to get the routing information to other nodes; The spanning tree is created dynamically with the group being created and members joining in the group; The packets are distributed by the tree to all members.The paper presents several measures to improve the system's robustness. Different measures are applied to the control topology and the data topology respectively which could reduce the performance losing by the failure of the nodes. Failure detecting and fast recovery are applied to the control topology while adding redundant virtual links (RVL) is applied to the data topology. Three different adding RVL strategies are used and are compared by simulated program. Experiment shows that adding RVLs can markedly improve the system's robustness.The packets' transmission latency is the key issue cared by applications, the paper also ameliorates the main part which brings on the latency. Four different partial improving steps are adopted to meliorate the sub tree formed by the leader nodes; Probabilistic transformation is used to adjust the sub tree in order to gain better result. Simulated experiment shows that the improving means do well, which can greatly reduce the packets' transmission latency.At last the paper presents the implementation of the application layer multicast system.