Wavelength routing and optical network lalyer protection approaches against single link failures for multicast traffic on WDM networks

Abstract

As optical wavelength division multiplexing (WDM) networks are now widely recognized as the core of next generation broadband networks and multicasting is also increasingly becoming important in modern communication networks, this thesis investigates two significant problems of optical WDM networks on which multicast traffic is supported. As the first research problem, the multicast routing and wavelength assignment (MC-RWA) problem that refers to the problem of routing multicast traffic and assigning wavelengths to it on WDM networks is systemically analyzed. For the MC-RWA problem, mesh and multi-ring design approaches are intensively studied. Key aspects that are taken into consideration and comparison of those two design approaches include fiber requirements, fiber utilization, and complexity of network operation and management. Moreover, the influences of the maximal wavelengths multiplexed per fiber, splitting degree of optical power splitters, and wavelength conversion on fiber requirements are investigated in this thesis. Integer linear programming (ILP) formulations are derived and used as a solution technique to obtain the fiber requirement of each studied design approach. Finally, heuristic algorithms to perform wavelength allocation and a lower bound on the fiber requirement are discussed. As the second research problem of this thesis, the multicast optical protection problem that refers to the problem of provisioning protection systems to multicast traffic on WDM mesh networks is investigated. To solve this problem, two main categories of protection systems are considered. For the first category, six new multicast protection strategies against single link failures are designed and introduced. For another protection category, an extension of point-to-point protection techniques to protect multicast traffic is presented. In this category, five protection strategies are studied. The main objectives to study the optical protection problem are to examine the ease of restoration process, the working and spare fiber requirement of each studied protection approach, and also to compare those examined terms among studied protection approaches. Moreover, techniques for wavelength allocation and spare capacity placement for restorable WDM networks are comprehensively studied. To achieve the main objectives, ILP mathematical models are developed to minimize the working and/or spare fiber requirement. Finally, this thesis introduces wavelength allocation and ILP-based heuristic algorithms as alternative tools to obtain the working and spare fiber requirement. Based on network experiments, the numerical results demonstrate that the multicast protection methods generally require fewer fibers than the point-to-point protection methods. However, in an environment of networks supporting both unicast and multicast traffic simultaneously, additional fibers required for point-to-point protections are compensated by a single and simpler network protection control plane. This is in contrast to a network using a multicast protection system that requires an extra control plane for link restoration of multicast traffic. In addition, the network design outcomes show that the proposed ILP-based heuristic algorithm potentially generates near-optimal solutions for designing multicast WDM networks both with and without link protection.