Light-tree based protection strategies for multicast traffic in transport WDM mesh networks with multifiber systems

In this paper, we consider the problem of how to manage faults in multicast WDM mesh networks in which the multiple fiber system is employed. By using the concept of light-tree to support multicast sessions, four new multicast protection strategies against single link failures are proposed, namely, light-tree reconfiguration (LR), light-tree-interrupted reconfiguration (LIR), optical branch (OB), and optical-branch-fixed (OBK) protection strategies. The proposed multicast protection strategies are comprehensively analyzed and compared in aspects of the total wavelength capacity requirements to make networks restorable, the ease of restoration management and operation, and the practical feasibility. To guarantee 100% network survivability, we provide mathematical formulations for achieving optimal multicast routing and wavelength assignment (MC-RWA) so as to determine the minimum spare capacity requirement in each proposed protection scheme. Finally, in this paper, the influences of the number of wavelengths multiplexed in a fiber and the limited splitting degree of optical power splitters on the wavelength capacity usage are also intensively investigated.