Researches On Multicast Congestion Control Technologies

The global information infrastructure has witnessed explosive growth in recent years. It has transformed society and pervaded every aspect of our lives, from business and communication to education and entertainment. This has given rise to an ever-increasing need to new applications, and especially applications involving the reliable transfer of large volumes of data from a source to multiple destinations across wide-area networks are expected to become increasingly important in the near future. A few examples are point-to-multipoint ftp, news distributions, Web caching and software updates. Multicast technology promises to enhance the capabilities of wide-area networks for supporting these applications. Multicast transport mechanisms have been a topic of intense research and development efforts over the past couple of years. Both the Internet Engineering and Internet Research Task Forces (IETF and IRTF) have been heavily involved in coordinating multicast transport protocol research, development and standardization.However, congestion control for multicast protocols has emerged as one of the biggest challenges in the large-scale deployment of multicast applications in the Internet. It also is a hard problem and an active research area. Since developing congestion control mechanisms is crucial to enable reliable multicast transport protocols to be deployed for the Internet, the IRTF Reliable Multicast working group has considered it a priority area. At present, there are no standardized, Internet-based multicast transport protocols that provide effective, dynamic congestion control methods for safe wide-scale deployment of end-to-end rate adaptive applications. The IETF has pointed out that effective congestion control mechanisms must be proposed before standardizing multicast protocols. Recent researches and standardization efforts are addressing these issues.In this paper, Chapter 1 gives a general introduction to multicast congestion control. First the background and the cause of multicast congestion are introduced, and then the necessity of implementing multicast congestion control is analyzed. We also discuss the research work related to multicast congestion control. Finally existing problems in current multicast congestion control are proposed.Chapter 2 focuses on the principal problems such as TCP-friendly, scalability, fairness, and discusses kinds of solutions. Then we describe the lastest researches and developments on multicast congestion control algorithms and classify them from different aspects. Furthermore,different algorithms are analyzed and compared, and some problems are pointed out. To order to solve above problems, we design a novel rate-based multicast congestion control scheme - RBMCC, which uses the active explicit congestion indication and representative-based feedback control scheme to inform the source of the status of the network, and alternate the send rate by adjusting the packet intervals between packets. The goal of the dynamic congestion control algorithm is to make the entire system responsive to the changes as rapidly as possible in the offered loads or available bandwidth without getting into an oscillating behavior.We also present a number of simulations to demonstrate and evaluate the efficiency and performance of RBMCC in Chapter 4, including analysis TCP fairness, responsiveness, scalability and so on. The simulation results show that RBMCC improves the dynamics and sensitivity to response, and can adequately make use of the available resource of the network . Besides, it also has good TCP-friendliness.Although congestion control is required by all applications to ensure network safety, different applications have various constraints in speed, quality and consistency of data delivery. For example, real-time video applications can trade quality for speed, while applications for software distributions can trade latency for reliability. One can not make a single multicast congestion control scheme to meet requirements of all applications. RBMCC is to a...