Using GRASP and GA to design resilient and cost-effective IP/MPLS networks

The main objective of this thesis is to find good quality solutions for representative instances of the problem of designing a resilient and low cost IP/MPLS network, to be deployed over an existing optical transport network. This research is motivated by two complementary real-world application cases, which comprise the most important commercial and academic networks of Uruguay. To achieve this goal, we performed an exhaustive analysis of existing models and technologies. From all of them we took elements that were contrasted with the particular requirements of our counterparts. We highlight among these requirements, the need of getting solutions transparently implementable over a heterogeneous network environment, which limit us to use widely standardized features of related technologies. We decided to create new models more suitable to fit these needs. These models are intrinsically hard to solve (NP-Hard). Thus we developed metaheuristic based algorithms to find solutions to these real-world instances. Evolutionary Algorithms and Greedy Randomized Adaptive Search Procedures obtained the best results. As it usually happens, real-world planning problems are surrounded by uncertainty. Therefore, we have worked closely with our counterparts to reduce the fuzziness upon data to a set of representative cases. They were combined with different strategies of design to get to scenarios, which were translated into instances of these problems. Finally, the algorithms were fed with this information, and from their outcome we derived our results and conclusions

Optimización de costos en redes multicapa robustas.

Fibras ópticas, transporte óptico (DWDM), transporte TDM (SDH), redes ATM, IP y MPLS, con distintos grupos de operación brindándose servicios entre sí. Los overlays tanto tecnológicos (distinto tipo de equipos) como administrativos (distintos grupos de operación), son una realidad instaurada desde hace un buen tiempo en las redes. Ya sea por: razones históricas, conveniencia organizacional (distintos negocios de una misma empresa que se arriendan recursos entre sí), justificación económica (una empresa que arrienda recursos de otra de mayor escala o penetración) o imposición regulatoria; esta situación es presente y debemos acostumbrarnos a pensar que las redes se brindan servicios entre sí. Este trabajo da una aproximación para resolver el problema de como desplegar una red, haciendo uso de recursos de un overlay inferior, en forma robusta1 y a costo óptimo. Adelantamos que los resultados obtenidos han colmado ampliamente nuestras expectativas. En lo económico; de poder llevarse a cabo la mitad de los cambios propuestos, este proyecto se pagaría con los ahorros generados en 2 semanas. En lo académico, hemos encontrado diversos resultados teóricos interesantes. En lo estratégico, hemos identificado algunos problemas estructurales en las redes del cliente, que suponemos dispararán su análisis y solución, antes que representen un problema importante

Optimal design of a Multi-Layer Network :An IP/MPLS over DWDMapplication case

In this paper we study a network design problem arising from the deployment of an IP/MPLS network over an existing transport infrastructure. The goal is to find a minimum cost installation of links such that traffic demands can resiliently be accomplished. We present an integer programming formulation for our problem and metaheuristics to find good quality solutions. This work is based on a real application case for a telecommunications compan

Optimal design of an IP/MPLS over DWDM network

Different approaches for deploying resilient optical networks of low cost constitute a traditional group of NP-Hard problems that have been widely studied. Most of them are based on the construction of low cost networks that fulfill connectivity constraints. However, recent trends to virtualize optical networks over the legacy fiber infrastructure, modified the nature of network design problems and turned inappropriate many of these models and algorithms. In this paper we study a design problem arising from the deployment of an IP/MPLS network over an existing DWDM infrastructure. Besides cost and resiliency, this problem integrates traffic and capacity constrains. We present: an integer programming formulation for the problem, theoretical results, and describe how several metaheuristics were applied in order to find good quality solutions, for a real application case of a telecommunications company