Research And Improvement On Reliable Multicast Protocol

With the development of Internet, more and more single-multipoint data transmission applications came into being. Multicast is better suited this one-to-many data transmission than the traditional unicast and broadcast. Traditional multicast has a good utilization of the network and a high saving the resources of the characteristics of the sender, but can not guarantee that all data are reliably and orderly delivered to each multicast member. Reliable multicast protocol multicast research has become a hot issue. Currently, there are many researches and improvements on reliable multicast, most of them research and improve on multicast in terms of the error control and recovery, congestion control. Error control and recovery is further divided into automatic repeat request ARQ, forward error correction FEC, ARQ and FEC mixed. Automatic repeat request ARQ is often used because it's relatively simple, but the feedback implosion which ARQ feedback mechanism arise brings challenges to the scalability of reliable multicast.This paper, starting from the basic concepts of multicast, described the working principle of multicast, the concepts and need of reliable multicast, and detailed information on the core technology for reliable multicast - error control and recovery and congestion control.Then in order to solve the problems which feedback implosion bring to the scalability of reliable multicast, the paper improves traditional reliable multicast protocol from the perspective of the NACK compression and puts forward the idea of setting the timer to the feedback, and reduces the number of NACK packets more effectively by making the feedback sent base on the length of packet. It sets the parameters, enhances the real-time system on the basis of avoiding feedback implosion effectively. The article also tests the significant effect on NACK compression of the improved protocol through the NS system simulation experiment.Finally, the paper introduces the application of the improved protocol in the intelligent public transport projects. The application of the protocol in the wireless download part of the monitoring center not only reduces the working hours of the monitoring center and the waiting time of car terminals, but also reduces the increased runoff of the network caused by the feedback, while enhancing the reliability of data transmission so that the system no longer worries about the data transmission errors caused by the instability of the wireless network when using of the convenience of wireless network data transmission.