The Research On Reliable Multicast Algorithms For Streaming Media Based On Active Network

The widely applied IP Multicast technique caters to demands for multicasting in large scales as well as brings about new problems; especially that it does not ensure reliability due to its"best-effort"nature. Reliable multicast technology has been developed to solve the problems of reliability. Streaming media will be the main application in the future, the streaming applications are more flexible to network loss than classical data application, but heavy packet losses will lower the media playback quality. Multicast reliable transmission is also very necessary for networked streaming media. It is more and more clear that assistance from routers would improve the performance of reliable multicast protocols, and active network technique is of advantage to reliable multicast.In this thesis, we firstly discuss the challenges of providing error recovery and congestion control for reliable multicast. At the same time, some related work is stated. Then thesis proposes two reliable multicast algorithms based on active network: ARMER for error recovery and ARMCC for congestion control.(1) ARMER is a reliable multicast algorithm that active router carry out error recovery with replier assisted. Our algorithm includes five mechanisms: loss detection, replier selection, NACK handling, local recovery and scoped retransmission, buffer management and periodical ACK feedback. ARMER makes the best of active service in active router; in addition, replier connected with active router assists retransmission, and relieves some pressure of active router. Our algorithm solves the problem of feedback implosion and retransmission nuisance, facilitates fast and efficient error recovery, has good scalability, and is suitable for large-scale multicast applications.(2) ARMCC is a router-assisted rate-based reliable multicast congestion control algorithm. Our algorithm includes five mechanisms: hierarchical RTT measurement, congestion detection, rate adjusting, and congestion smoothing buffer management. With flexible use of the resources in active router, ARMCC can not only let multicast flows have an adjustable share of bandwidth of bottleneck links with TCP flows, achieve inter-protocol fairness, but also limit the effect of congestion on a specific link to a small region,...