Beker, Sergio Ariel (2004) Optimization Techniques for the Dimensioning and Reconfiguration of MPLS Networks. PhD thesis Informatique et Réseaux, ENST - INFRES Informatique et Réseaux, ENST.

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Abstract

The calculation of virtual topologies on mapped onto physical topologies is one of the main techniques in traffic engineering. For a given physical network topology with fixed capacities, and a traffic matrix to route, the problem is the one of finding a virtual topology which will optimally route the given traffic matrix over the physical topology. When the traffic matrix evolves on long timescales, we will need to recalculate such optimal layout. Our first contribution consists in the definition of cost functions which better represent the actual costs of operation from an operator's standpoint. The second contribution consists in taking into account the costs of reconfiguring the layout to adapt it to the new optimal layout. Considering actual operation and maintenance costs, it would be interesting to reduce the layout complexity, measured as a function of the number of virtual paths required by the layout. We have formulated different optimization problems minimizing layout complexity, under QoS constraints. This realistic model results in hard to solve problems. We have developped heuristic methods to approximatelly solve large network topologies. We have shown the interest of reducing the layout complexity compared to results obtained when optimizing the layout with classical cost functions. The layout reconfiguration induces first a cost of operation, and second a cost associated to the service disruption times needed to reconfigure. We have formulated a family of problems which take into account the reconfiguration costs when calculating the new layout. One of the above mentioned heuristics has been adapted to solve the reconfiguration problem.

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