Study On IP Dynamic Multicast Routing Algorithm

In computer network, multicast technique is an important approach of communication, in which a sender concurrently transmits data to multiple receivers. The approach has been widely used in real time multimedia applications such as video/audio conferencing, video on demand, remote education and so on. Multicast routing can be classified into static multicast routing and dynamic multicast routing. Study of dynamic multicast routing is an important focus in this field. After careful analysis of some existing non-rearrangeable dynamic multicast routing algorithms, this paper presents firstly a non-rearrangeable dynamic multicast routing algorithm, named as DCSMP, based on a unique special minimal path, and extends it to an algorithm with delay and bandwidth constraints. DCSMP takes advantage of those destination cost optimization algorithms while overcomes the latter's disadvantage in optimizing network cost. DCSMP can not be affected by randomized unpredictable changes in multicast members during multicast communications, and avoids the serious degradation in multicast performance, as is the case in greedy algorithm. In addition, in case of a node joining a multicast group, DCSMP preferentially choose special minimal path including key nodes under some conditions, thereby, making it possible for subsequent multicast nodes on their way to multicast tree passing through these key nodes. More link share is implemented and multicast tree cost is reduced. Simulation results show that DCSMP is of good performance. In terms of maximum cost competitiveness, DCSMP is smaller than that of both GA and SP, indicating more stable performance. Secondly, after careful study of several existing rearranged-type dynamic multicast routing algorithms, say, completely rearranged, partially rearranged, and trigger rearranged, this paper presents a new trigger rearranged dynamic multicast routing algorithm, named as CRKDMR, and extends it to an algorithm with delay and bandwidth constraints. CRKDMR uses triggering to do routing rearrangement, which avoids the frequent changes of routing tables and removes associated influence on network stability, which would occur in complete rearrangement and partial rearrangement. It eliminates unnecessary routing rearrangement as well. Moreover, in comparison with existing trigger rearranged algorithms, CRKDMR would preferentially choose the shortest path including key nodes on certain conditions when a node joins a multicast group, thereby making it possible for subsequent multicast nodes also going through these key nodes on their way to multicast tree. This added possibility can be beneficial to implementing more link share and reducing multicast tree cost. Furthermore, trigger function of CRKDMR is more comprehensive and reasonable than that of existing trigger rearranged dynamic multicast routing algorithms. It reflects more the influence of changing multicast members on the quality of multicast tree in every aspect, while takes link share into account when subsequent nodes join multicast group in the long term. Simulation results show that performance of CRKDMR is better than that of other algorithms. Cost competitiveness and average tree change of CRKDMR are smaller, in the meantime, CRKDMR can achieve a better balance between performance of multicast tree and change of tree.