This thesis focuses on multi-domain routing for traffice engineering and survivability support in optical transport networks under the Generalized Multi-Protocol Label Switching (GMPLS) control framework. First, different extensions to the Border Gateway Protocol for multi-domain Traffic Engineering are designed and evaluated. Throughout the thesis three extensions are proposed: and end-to-end aggregated TE metric per destination, an extension for multi-path dissemination, and an AS-disjoint path selection modification. It is shown that simple TE metrics applied within the BGP path selection process are not enough for efficient TE in mesh multi-domain networks. Enhancing the protocol with multi-path dissemination capability, combined with the employment of an end-to-end TE metric proves to be a highly efficient solution. Simulation results show good performance characteristics of the proposed extensions, such as providing lower connection blocking and stable protocol overhead. Furthermore, different export policies for multi-path dissemination with the proposed BGP enhancements are designed and evaluated. Simulation results indicate that the amount of disseminated paths per destination is not as essential for improved network performance as the length of the provided paths. Second, the issue of multi-domain survivability support is analyzed. An AS-disjoint paths is beneficial not only for resilience support, but also for facilitating adequate network reactions to changes in the network, which trigger BGP protocol re-convergence. By notifying the proper network elements for changes in the network (e.g. failures), the connection blocking can be significantly reduced. Furthermore, novel restoration mechanisms, which provide differentiated failure handling, are proposed and evaluated. It is shown that the applied routing protocol and the topology of the multi-domain nework have very strong influence on the efficiency of the applied restoration techniques. Finally, different challenges of the integration of the GMPLS control framework with the novel Optical Burst Switching technology are analyzed. Existing integration architectures are discussed and categorized and solutions for different protocol extensions are proposed.
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Dittmann, Lars, Ellegård, Lars, Buron, Jakob Due, Ruepp, Sarah Renée