Researches On QoS Multicast Routing Problems

The recent proliferation of QoS-aware group applications over the Internet, such as videoconferencing, news distributions, distance learning, software upgrading etc, has accelerated the need for scalable and efficient multicast support. Multicast is a more efficient transport mechanism than unicast on point-to-multipoints data transmitting. In the traditional unicast the source need to send an individual copy of the same data to each receiver, so a single stream may unnecessarily require a large portion of the available network bandwidth, if there are thousands of receivers, it maybe give rise to network congestion. While in the multicast there is only one copy of the same data on the main path links and the routers make copies only on the branches, so it uses the least network bandwidth. The multicast data transporting topology is a multicast tree and nowadays more and more multimedia applications require QoS guarantees, so how to build a multicast tree that meet the corresponding QoS constraints has emerged as one of the biggest challenges in the field of multicast research. Many researchers have been heavily involved in studying and designing QoS multicast routing algorithms and protocols. QoS multicast routing has been a topic of intense research and development efforts over the past couple of years. In this paper, Chapter 1 gives a general introduction on QoS multicast routing. First the preliminary knowledge of multicast is introduced, and then the multicast routing is analyzed. And in order to meet QoS constraints, we also discuss the research work related to QoS multicast routing. Finally existing problems in current QoS multicast routing are proposed. Chapter 2 focuses on the problems of QoS multicast routing. First the types of multicast tree and the characteristics of each type are described. Then we introduce several multicast routing protocols that are in common use and classify them into two kinds. Finally, the concept of QoS is introduced and on this point, we state the QoS definition, QoS metrics, QoS network model and QoS routing problem. In QoS multicast routing, to find a feasible path that meet multi-constraints is a NP-complete problem. In chapter 3, we propose an algorithm for delay and delay variation less cost multicast tree problem which bases on two ideas: Dijkstra algorithm on mixed weight and core based tree. In recent years, multi-path routing and mixed-path routing besides single-path routing have received more and more attention. In chapter 4 we analyze and compare the three routing methods and based on which we put forward a new algorithm for QoS multicast routing QoSMRA that makes use of local search, source search, single-path routing and multi-path...