engleski

Heuristic Algorithms for Virtual Topology Design and Routing and Wavelength Assignment in WDM Networks

This thesis investigates the problem of designing virtual topologies in wavelength routed WDM (Wavelength Division Multiplex) optical networks. In such networks, a virtual topology is created over the physical optical network by establishing all-optical connections, called lightpaths, between pairs of nodes. Transport via a lightpath is entirely in the optical domain. A virtual topology can also be composed of a set of light-trees which optically connect a subset of nodes in the network. In order to establish a virtual topology, it is necessary to determine a set of lightpaths/light-trees, find for them corresponding paths in the physical topology and assign wavelengths to them. Finally, packet-switched traffic is routed over the virtual topology. The thesis focuses on the problem of routing and assigning wavelengths to lightpaths and light-trees, and the virtual topology design problem in WDM networks. These problems are NP-complete so heuristic algorithms are needed to help solve them. Proposed are efficient heuristic algorithms for the Routing and Wavelength Assignment (RWA) of static and scheduled lightpath demands. Furthermore, developed is a heuristic for multicast routing and algorithms for static multicast RWA. Virtual Topology Design is investigated considering various objective criteria, and an additional objective criterion is proposed. Efficient heuristic algorithms are developed to help solve this problem. To assess the quality of the solutions obtained by the proposed algorithms, new analytical lower bounds for the corresponding problems are developed.

WDM; wavelength routed optical networks; routing and wavelength assignment; virtual topology design; heuristic algorithms; lightpaths/light-trees; bin packing; optical multicasting; tabu search; GRASP

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