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. But the congestion control of multicast has not solved,this has been its bottleneck. As we know multicast mostly is UDP,which has no restriction during the transmission so as to it cannot live up to "best-effort",and that UDP can influence the transfers of TCP. Increasing UDP deteriorates the ability of TCP to control congestion and is a source of high drop rates. Face these questions this paper proposed an Efficient Congestion Avoidance Mechanism(ECAM) which start from basal theory. ECAM has SQ as feedback message so it reduced the request that reliability of the data. At the same time it combine RED is sensitive to incipient congestion and ECN is good at deal with congestion this make it deal with the congestion rapidly and effectively. We simulate ECAM on NS2 when choice different parameter and network,the results show that ECAM significantly reduces packet loss,enhance UDP to fairly coexist with TCP flows.