Research On QoS-based Dynamic Multicast Routing

Multicast is a mechanism to efficiently support multi-point communications. IP multicast utilizes a tree delivery structure, on which data packets are duplicated only at fork nodes and are forwarded only once over each link. This approach makes IP multicast resource-efficient in delivering data to a group of members simultaneously and can scale well to support very large multicast groups. The core of multicast mechanism is routing problem, and designing & selecting appropriate multicast routing algorithm is very important to efficiently implement multicast routing. Multicast routing protocol is the key of solving routing problem, which is the implement of multicast routing algorithm, and provide the mechanism of deliverying member informations and the method in deliverying datagram. Many multicast routing algorithms and protocols had been proposed and developed, and several routing protocols have been standardized or are in the process of being standardized by IETF. As the network may very big, and the topological structure and large amounts of traffic are changing continuously, the mutlicast routing problem is becoming very important and difficult. Dynamic joining and leaving of member, the participation of QoS information, the need of network hierarchical routing are the obstacles to solve multicast routing problem. Network routing not only have to satisfy the need of user's different application, but also develop the resource-efficiency of whole network. QoS-based routing can enable more effective and efficient QoS support by allowing dynamic route selection based on network resource availability and QoS requirements. Many multicast application, such as network game, teleconferencing, etc., need be satisfied by quality of service.The multicast routing problem that finding the minimum cost multicast routing tree with many QoS constraints may be formalized to Steiner tree problem in network, which is a NP-complete problem that an algorithm that finds a Steiner tree can not get the best solution in polynomial time. Therefore, we would like to find approximation algorithms which can get a solution that close to optiumum in worst case and average case. There were large amount of valuable method on multicast routing algorithms and protocols that have been proposed these days. But these algorithms and protocols are so complex and unfit to need of actual network that they are not attain abroad application. Applications urge multicast routing to combine with correlating protocols, and develop the advantage of mutlicast routing.In this thesis, we mainly research the problem on QoS-based dynamic multicast routing, and analized many algorithms and protocols. At same time, we also proposed a protocol frame, and implement a QoS-obvioiusly multicast routing protocol—QoSMIC. In this thesis, some current dynamic multicast routing algorithms and protocols are researched and analized systemically, and the basic mathematic model that multicast routing algorithms and protocols used are summed up, and the mathematic model of QoS-based dynamic multicast routing problem is concluded, and the architecture of QoS-obviously multicast routing and the ralation of multicast routing protocols are highly gathered up. In this base, we proposed some problems that sould be solved: dynamic problem, QoS problem, and hierarchical problem, and provide some discuss in theory to solve these problems. These analysis and discuss are the base of later theory research and practice.In this thesis, we research two representative protocol:PIM-SM and QoSMIC protocol, and their implemention. We implement QoSMIC protocol in OPNET network simulation model, and described the detail of this implemention. These work make us attain further knowledge on QoS-based protocol, and make a base on later building multicast routing protocol. Firstly, this accumulates some experience on implementing protocols. Secondly, this provided a model that can contrast between other further protocol and this protocol. Thirdly, this accumulates our knowledge about QoS m...