Switch Placement Algorithms in Optical WDM Heterogeneous Networks

• Main Authors: Hsiao-Tse Chang, 張孝澤
• Other Authors: Yeong-Sung Lin
• Format: Others
• Language: en_US
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/21201778259612593231

碩士 === 國立臺灣大學 === 資訊管理學研究所 === 93 === With the rapid development of Wavelength Division Multiplexing (WDM), a fiber can carry more and more wavelengths, but the complexity and the cost of Optical Cross-connects (OXCs) also increase. To deal with the problem, General Multi-Protocol Labeling Switching (GMPLS) defines three kind of switching methods: fiber switch capable, waveband switch capable, and lambda switch capable. In a heterogeneous optical network, we allow each node to have one of the switching capabilities. OXCs contribute most to the planning cost of optical networks, and the cost of OXCs is in proportion to the number of ports. Therefore, while a fiber can carry hundreds of wavelengths, the cost of OXCs increases proportionally. Furthermore, there is still a shortage of ports in the OXC design. In this thesis, we allocate the switch nodes properly based on the lowest cost, and satisfy all the static traffic demand in a heterogeneous network. We model this problem as an integer programming problem with an objective function and several constraints, which is very complicated. Since the routing and wavelength assignment problem (RWA) is a well known NP-hard problem, and our problem contains the RWA problem, our problem is also NP-hard. As we cannot solve it in polynomial time by well known algorithms, we adopt Lagrangean relaxation as the solution approach. In addition, we propose a simple heuristic algorithm modified from an RWA problem, and conduct several experiments on different network topologies. We find that the experiment results of Lagrangean Relaxation are better then those of the simple heuristic algorithm.