| Optical networks consisting of optical cross-connects (OXCs) arranged in some arbitrary topology are emerging as an integral part of the Internet infrastructure. The main functionality of these networks will be to provide reliable end-to-end lightpath connections to large numbers of electronic label switched routers (LSRs). We consider two problems that arise in building such networks. The first problem is related to the topology design of optical networks that can grow to Internet scales, while the second is related to the light-tree routing for the provision of optical multicast services.; In the first part of the thesis, we present a set of heuristic algorithms to address the combined problem of physical topology design (i.e., determine the number of OXCs required for a given traffic demand and the fiber links among them) and logical topology design (i.e., determine the routing and wavelength assignment for the lightpaths among the LSRs). We then extend our study to take protection into consideration, and we present a detailed analysis and comparison of different protection strategies. In order to characterize the performance of our algorithms, we have developed lower bounds which can be computed efficiently. We present numerical results for up to 1000 LSRs and for a wide range of system parameters such as the number of wavelengths per fiber, the number of transceivers per LSR, and the number of ports per OXC.; In the second part of the thesis, we study the problem of constructing light-trees under optical layer power budget constraints, with a focus on algorithms which can guarantee a certain level of quality for the signals received by the destination nodes. We define a new constrained light-tree routing problem by introducing a set of constraints on the source-destination paths to account for the power losses at the optical layer. We investigate a number of variants of this problem, we characterize their complexity, and we develop a suite of corresponding routing algorithms. We find that, in order to guarantee an adequate signal quality and to scale to large destination sets, light-trees must be as balanced as possible. Our algorithms are designed to construct balanced trees which, in addition to having good performance in terms of signal quality, they also ensure a certain degree of fairness among destination nodes. |
