Research & Improvement On Reliable Multicast Protocol

With the development of current Internet, more and more applications require data to be delivered reliably from one sender to many receivers. Under this circumstance, reliable multicast protocols are better suited for this one-to-many communication than conventional transport layer unicast protocols. The applications in Internet often involve hundreds to tens of thousands of recivers, so how can we make the reliable multicast protocols adapt to network and membership changes, that is to say how to make the reliable multicast protocols more scalable is the core problem that many researchers try to solve. Especially in the time-sensitive applications, they require the scalable reliable multicast can provide both low recovery latency and high bandwith utilization. However, the recovery latency and bandwith utilization are a great tradeoff. Although the previous researches on reliable multicast protocols have made some efforts on the scalability, yet it can not solve the implosion and exposure problem on the basis, which reduces the bandwith utilization.This thesis began with the basic concept of multicast, described the principles, merits together with flaws of most IP multicast routing protocols and gave the summary of source specific routing protocols and shared tree routing protocols. Then the author analyzed the problem on current scalable reliable multicast protocols and the improvement as well as limitations of previous works in great detail. Afterwards.the author adoped the light weight multicast service ideal and improved the Tree Based Multicast Transport Protocol which was used widely in data dissemination.In this thesis,the new protocol was named HRMS (Hierarchical Recovery using MBTrace and Subcasting) that based on the hierarchy which was used in TMTP. HRMS added a little extension to the network layer of the multicast routers, which made the logical recovery fusion tree consistent with the multicast transmission tree, at the same time, it employed an efficient recovery multicasting mode named subcasting, all these eliminated the problems concerned with implosion and exposure. At the end of the thesis, the author gave the simulation results of several reliable multicast protocols that did some improvement on scalability.We can conclude that HRMS makes a better tradeoff between the packet delivery latency and the traffic load.