Studies On QoS Multicast Routing Technology In IP Networks

With the development of computer network technology, multimedia is enormously applied to real time video conference, VoD and long-distance teaching, etc. Their common feature is to transmit information from one or multiple source nodes to multiple destination nodes. As these real-time operations are sensitive to delay, delay-jitter, packet-loss and cost in the network transmission, they are liable to be affected by the operation portfolios of FTP and HTTP, and thus demand QoS to assure real time communications. Traditional internet routing protocols, such as OSPF and RIP, are routing technology based on "shortest path algorithm" in which the route is optimized with a single metric, and just offer "best-effort" service rather than QoS. Meanwhile, the theoretic research and realization of the multicast routing algorithms and protocols based on QoS have become a major research topic with the rapid development of such high-powered network technologies as mobile networks and AON All Optical Network and the progressive expansion of the scopes of their applications.QoS routing is how to select network routes with sufficient resources for the requested QoS parameters. In comparison with best-effort routing, QoS routing has some constraints and mostly is NP complete problem. Multicast routing is a network-layer function. A fundamental issue in multicast communication is how to determine an effcient message route (multicast routing). Tree construction is a commonly used approach in solving the multicast routing prolem. multicast routing algorithms are used to compute multicast trees that satisfy QoS requirements.Now, the propsed heuristic algorithms can't meet the QoS requirements for computation complexity, and adapt to large groups with member join dynamically for their expansibility. A method for the QoS multicast routing is presented based on the summary of the algorithms and protocols proposed in the past. The research mainly concentrates on the algorithms and protocols of QoS multicast routing, ant algorithms and the mobile agent optimization routing in IP networks. In detail, the contributions of this paper include the following.1)Firstly, the analysis on the strategy of QoS routing and QoS multicast routing problem in IP networks are done by studying the status quo of QoS multicast routing. Secondly, based on the definition and mechanism of IP QoS , the research on the IntServ, RSVP, DiffSer, MPLS, the comprehensive implementation strategy of QoS in IP network and the implementation of IP QoS in Linux are conducted. Finally, an approach to QoS multicast routing algorithmsand protocols in NS2 is presented by studying QoS multicast routing mechanism.2)It discusses multicast routing problem with multiple QoS constraints of delay, delay jitter, bandwidth and cost metrics, describes a network model for researching the routing problem, and presents a dynamic multicast routing algorithm with multiple QoS constraints (DMRAQoS). In DMRAQoS, a multicast group member can dynamically join or leave a multicast session with no disruption of the multicast tree. Simulation results demonstrate that DMRAQoS provides an effective path for the research on multicast routing with multiple QoS constraints.3)The objective of multicast routing optimization is to make network resources utilization more effective by a connected mode to find an algorithm or strategy in the case of given network and multicast request. In this paper, firstly, genetic algorithms, simulated annealing and neural network are discussed and a globally optimal multicast routing algorithm (MROAQoS) is presented based on the ant colony ability of finding a shortcut between their nest and food sources in the process of hunting for food. Secondly the MROAQoS is modified according to application demand. Lastly, a mobile agent multicast routing algorithm with multiple QoS constraints (MAMRQoS) is presented, the mobile agent model in NS2 is designed and the validity and effectiveness of the MAMROoS is demonstrated.4)It presents a multicast routing protocol with multiple QoS constraints (MRPMQoS) based on the analysis on the protocols of YAM, QoSMIC and QMRP. The MRPMQoS does not maintain global network state but only requires the local state information of the link (or node). The MRPMQoS effectively decreases the overhead for constructing a multicast tree, diminishes the delay of the nodes join, and improves the success ratio of seeking links by combining single-branch search and multi-branch search. Simulation results show that the MRPMQoS provides an available means to implement multicast routing, and can adapt to all kinds of the topology networks and has good expansibility.5)It describes a network model for the hierarchical multicast routing with multiple QoS constraints, persents a QoS-based on hierarchical multicast routing protocol(HMRPQoS), which is based on the analysis on hierarchical routing and hierarchical QoS multicast routing algorithms. HMRPQoS solves the expansibility of the large scale networks.This paper is supported by Natioal Natural Science Foundation of China(90304018,60172035).