Evaluation of restoration techniques incorporating optimal principle in WDM optical networks

Numerous researchers have proposed restoration techniques incorporating the concept of shortest disjoint paths in Wavelength Division Multiplexing (WDM) optical networks. The concept of shortest disjoint paths that obeys the strong optimal principle and the weak optimal principle is very important because shorter wavelength mileage including optical fiber distances is a dominant factor for the design of a survival WDM optical network. Even if restoration techniques incorporating the concept of shortest disjoint paths are faster, simpler, and easier than any other restoration techniques, we need to evaluate how well the concept of shortest disjoint paths is incorporated for the design of a survivable WDM optical network. In this paper, topology dependencies related to the concept of shortest disjoint paths are first developed. Then, seven objective functions that yield objective goals significant to the optimal design of a survivable WDM optical network are proposed and mathematically formulated. Finally, we develop ASDP (Near-Optimally Annealed k-Shortest Disjoint Path Restoration) and BBD (Branch-and-Bound with Dynamic Programming Principle) restoration algorithms that examine the proposed objective functions. Numerical results by experimenting ASDP and BBD algorithms show that the concept of shortest disjoint paths yields the best performance in terms of total and average restoration time. However, the concept of shortest disjoint paths does not seem to be an optimal technique in terms of significant optimal objective goals: minimal wavelengths, minimal wavelength link distance, minimal wavelength mileage costs, and even distribution of traffic flows.