Research On The Multicast Grooming Algorithm Of Light-path And Light-tree Combination

In recent years, with the rapid development of multicast applications such as the conference call, remote conference, IPTV, the traffic in the Internet increases rapidly, the communication network of bandwidth and capacity requirements are also getting higher and higher. Due to multicast request only need part of the capacity of a wavelength, we could multiplex several low-speed requests into a high-speed wavelength link through the way of traffic grooming.All of existing multicast grooming algorithm, the multicast grooming algorithm based on light-path has higher link utilization, and use less wavelengths, but with more grooming ports and larger energy consumption. Although the multicast grooming algorithm based on light-tree use less grooming ports and lower energy consumption, but the link utilization is low, and the use of splitter will reduce the signal-to-noise ratio. After analyzing and summarizing these two kinds of multicast grooming methods in detail, a new multicast grooming algorithm is proposed to improve the network performance, which absorbs the advantages of them and avoids their shortcomings.The main work of this thesis is as follows:(1) Propose a light-path and light-tree combination multicast grooming algorithm. In the grooming algorithm, choose optical domain multicast routing at the bottom of multicast tree to reduce the level of optical splitter of light-tree, and ensure the quality of the signal, reduce grooming port number; and electrical domain multicast routing at the upper to increase the link utilization. The simulation result shows that the new algorithm in most cases, could improve the network performance, but in some cases, improve only little effect. So a new advanced algorithm is proposed by optimizing the selection of the root node of established light-tree. On the one hand use the built light-path as far as possible to save grooming ports and improve the link utilization, on the other hand, ensure the validity of the new tree, prevent the new light-tree from selecting the improper root node and being abate, thereby improving the performance of the network. The simulation results show that this algorithm can achieve good results in different network environment.(2) Two energy-saving strategies are proposed based on the light-path and light-tree combination multicast traffic grooming algorithm. Strategy one by changing the structure of multicast grooming tree, to enable multicast traffic priority through the built light-path to route, and let isolated nodes through the nearest node connected to the multicast grooming tree, so that the length of the new light-path the is shortest, achieve the purpose of improving link utilization and saving the grooming ports. Also avoid obstruction in the source node caused by using too much grooming ports, thereby reduce the energy consumption. In strategy two, the splitter is added in the bifurcation point of multicast tree, through the splitter to realize multicast signal copy, save the grooming port and energy. The simulation results show that the two methods can achieve good energy-saving effect.