Application Layer Multicast Forwarding Tree Reconstruction Technology

Multicast has been the hot topic in the research of Computer Network, as the point-to-multipoint data transfer applications arise. However, more than a decade after its initial proposal, deployment of IP Multicast has been limited and sparse due to some reasons. In order to resolve the problems, some researchers propose application level multicast (ALM). The non-leaf nodes in the tree are normal end hosts, which are potentially more susceptible to failures. Thus an important problem in ALM is how to recover from node departures. On the question, there are two approaches to the recovery of the application level multicast tree. One is the reactive approach. Another is the proactive approach, which plans for departures before they happen. With the aid of proactive approach, a new delivery tree can be quickly restored.The research work is centered on reconstruction of forwarding tree. In this thesis, there are two parts in the main work. First, base on the comparative analysis of approaches to the recovery of the overlay multicast tree, we choose the proactive approach as emphases. In the part, the realization of algorithm is important. Through simulation experiments, we have realized several algorithms of proactive approach and analyzed the advantages and disadvantages of these algorithms. Second, base on the comparative analysis, we proposed a new algorithm-PLA, the core of which is a pre-plan model based on the proactive approach. In this part, Experiments is an important part. The simulation experiments have been made based on the new algorithm and experimental results are analyzed. Through experimentation and research, the following conclusions are drawn: PLA algorithm can reconcile the contradiction of "join-cost" and "backup-link-delay"; PLA algorithm can raise the performance of multicast forwarding tree.