Research On Algorithm Of ALM Route For Stream Media Over Peer-to-Peer

With the development of multimedia and network technology, application and research of stream media which is a cross-subject have made considerable progress. Multimedia has large data and demands wide bandwidth. Conventional stream media try to save bandwidth by using IP-multicast to transmit media data .However, IP-multicast depends much on devices in IP layer, and it needs to adjust or upgrade every device in IP layer. So it's unpractical to use IP-multicast widely. Therefore IP-multicast has not been largely applied for a long time. Application level multicast implements multicast in application layer, thereby it is convenient to use ALM by installing software rather than adjusting the structure of present networks. So that P2P stream media based on ALM has mushroomed.Theory of P2P networks ALM technology and stream media technique are summarized. Algorithm for construct ALM spanning tree which is applied in stream media living broadcast is introduced. The service ability of each node is difference and they may join or quit randomly while stream media is strict with scheduling when playing. So research on peer-to-peer live stream media confront with many challenge which is the key problem. A bandwidth considered proactive route maintenance method is given. In this method every non-leaf node maintains backup route for its children nodes before it leaves. So children nodes can quickly switch to backup route when their current parent node leaves. In order to improve the stability of the spanning tree it selects the node having the max service capability when computing backup route.The performance of our bandwidth considered proactive approach is evaluated using simulations. Simulation results indicate that the recovery time of our approach is much less than reactive method and is approximately equal to Yang's approach. The control overheads are smaller than Yang's approach and even smaller than reactive method in some special cases. Though the data delivery delay is a little larger than other methods the difference between them becomes smaller as the degrees of nodes increase.