Minimization of the network availability upgrade cost with geodiverse routing for disaster resilience

Telecommunication networks are a critical infrastructure of our society. Wide area backbone communication networks are based on optical networks, where each fiber has a very large capacity. These networks must offer high end-to-end availability and a high resilience to large-scale disasters. Routing with geodiversity can mitigate the impact of disasters but will result in longer paths, making it difficult to achieve the availability levels required by critical services. In this paper, we consider a given core optical network such that the current availability and the cost of upgrading it to a higher value are known for each network link (or edge). Then, the problem of selecting a set of edges to be upgraded at a minimum cost, while guaranteeing desired values of end-to-end availability and geodiversity, is considered and formulated as an arc based integer non-linear programming model. The non-linear constraints of the model are approximated and linearized, resulting in a new ILP based heuristic. A filtering procedure is proposed for decreasing (if possible) the cost and the number of upgraded edges of the solutions obtained by previously proposed greedy heuristics and also by the ILP based heuristic. The relative performance of the heuristics is evaluated using different geodiverse distances and end-to-end availability values in two reference core optical networks.publishe

Fundamental schemes to determine disjoint paths for multiple failure scenarios

Disjoint path routing approaches can be used to cope with multiple failure cenarios. This can be achieved using a set of k (k>2) link- (or node-) disjoint path pairs (in single-cost and multi-cost networks). Alternatively, if Shared Risk Link Groups (SRLGs) information is available, the calculation of an SRLG-disjoint path pair (or of a set of such paths) can protect a connection against the joint failure of the set of links in any single SRLG. Paths traversing disaster-prone regions should be disjoint, but in safe regions it may be acceptable for the paths to share links or even nodes for a quicker recovery. Auxiliary algorithms for obtaining the shortest path from a source to a destination are also presented in detail, followed by the illustrated description of Bhandari’s and Suurballe’s algorithms for obtaining a pair of paths of minimal total additive cost. These algorithms are instrumental for some of the presented schemes to determine disjoint paths for multiple failure scenarios.info:eu-repo/semantics/publishedVersio

Hierarchical Multiobjective Routing Model in MPLS Networks with Two Service Classes – A Comparison Case Study, Journal of Telecommunications and Information Technology, 2012, nr 2

A two-level hierarchical multicriteria routing model for multiprotocol label switching networks with two service classes (QoS, i.e., with quality of service requirements, and best effort services) and alternative routing is reviewed in this paper. A heuristic resolution approach, where nondominated solutions are obtained throughout the heuristic run and kept in an archive for further analysis is also reviewed. In this paper, an extensive analysis of the application of this procedure to two reference test networks for various traffic matrices is presented. Also a comparison of the results of our method with a lexicographic optimization approach based on a multicommodity flow formulation using virtual networks is carried out. Finally, results of a stochastic discrete event simulation model developed for these networks will be shown to illustrate the effectiveness of the resolution approach and to assess the inaccuracies of the analytic results

Um modelo de encaminhamento hierárquico multi-objectivo em redes MPLS, com duas classes de serviço

Tese de doutoramento em Engenharia Electrotécnica (Telecomunicações e Electrónica) apresentada à Fac. de Ciências e Tecnologia da Univ. de Coimbr

Mathematical Based Models for Group Decision Support in Telecommunication Network Design and Management—Challenges and Trends

The extremely rapid evolutions of telecommunication network technologies and services and their interactions with complex socio-economic environments, justify the increasing importance in applying, in certain areas of network planning, design and management, group decision approaches. In fact, there is a significant number of decision problems focused on issues of network planning and design, of multiple natures, where more than one decision maker intervenes or where it is possible to develop mathematical formulations of the problems considering multiple DMs, representing entities of the network itself. Moreover, the evolution of these networks and related industries leads to a great variety of multifaceted and complex problems, usually involving multiple dimensions, very frequently of conflicting nature. These factors justify the interest in addressing the applications of mathematical based models for group decision support in telecommunications. Although mathematical based models have been developed in the framework of operations research, systems science, game theory, etc., and they are an essential part of group decision and negotiation support systems, the scope of this study is limited to multicriteria models and game theory models. In fact, we believe these methodologies are adequate to discuss the challenges and trends of formal models for telecommunication applications. An outline of more relevant evolutions of telecommunication network technologies and services will be presented, followed by a brief overview of major concepts concerning multicriteria group decision (MCGD) and game theory (GT) approaches and methods, relevant to these areas. After identifying the major domains of application of MCGD and GT approaches in telecommunications, an overview of representative contributions in these areas, based on MCGD and GT methodologies, will be put forward. Finally, an analysis and outline discussion of current and future research trends and challenges concerning the use of MCGD and GT approaches in this broad area of decision support, also focusing on some relevant methodological issues, will be presented.This work was funded by ERDF Funds through the Centre’s Regional Operational Program and by National Funds through the FCT—Fundação para a Ciência e a Tecnologia, I.P. under the project CENTRO-01-0145-FEDER-029312. This work was also partially supported by FCT under project UIDB/00308/2020

A note on cascading failures in communication networks and power grids

An overview of recent works regarding the main aspects of cascading failures in interdependent power grids and communication networks, is presented. Modelling approaches to cascading failures propagation and strategies to mitigate the impact of those cascading effects are discussed. The identification of critical elements and robust design against cascading failures are also reviewed. Finally some concluding remarks regarding the need for a more realistic representation of the interaction between both networks are put forward.info:eu-repo/semantics/publishedVersio