@misc{BauschertBuesingD'Andreagiovannietal.2013, author = {Bauschert, Thomas and B{\"u}sing, Christina and D'Andreagiovanni, Fabio and Koster, Arie M.C.A. and Kutschka, Manuel and Steglich, Uwe}, title = {Network Planning under Demand Uncertainty with Robust Optimization}, issn = {1438-0064}, doi = {10.1109/MCOM.2014.6736760}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-42557}, year = {2013}, abstract = {The planning of a communication network is inevitably depending on the quality of both the planning tool and the demand forecast used. In this article, we show exemplarily how the emerging area of Robust Optimization can advance the network planning by a more accurate mathematical description of the demand uncertainty. After a general introduction of the concept and its application to a basic network design problem, we present two applications: multi-layer and mixed-line-rate network design. We conclude with a discussion of extensions of the robustness concept to increase the accuracy of handling uncertainties.}, language = {en} } @inproceedings{OrlowskiKosterRaacketal.2007, author = {Orlowski, Sebastian and Koster, Arie M.C.A. and Raack, Christian and Wess{\"a}ly, Roland}, title = {Two-layer Network Design by Branch-and-Cut featuring MIP-based Heuristics}, booktitle = {Proceedings of the INOC 2007, Spa, Belgium, also ZIB Report ZR-06-47}, publisher = {International Network Optimization Conference}, address = {Spa, Belgium}, year = {2007}, language = {en} } @inproceedings{RaackKosterOrlowskietal.2007, author = {Raack, Christian and Koster, Arie M.C.A. and Orlowski, Sebastian and Wess{\"a}ly, Roland}, title = {Capacitated network design using general flow-cutset inequalities}, booktitle = {Proceedings of the INOC 2007, Spa, Belgium, also ZIB Report ZR-07-14}, publisher = {International Network Optimization Conference}, address = {Spa, Belgium}, year = {2007}, language = {en} } @incollection{KosterOrlowskiRaacketal.2008, author = {Koster, Arie M.C.A. and Orlowski, Sebastian and Raack, Christian and Baier, Georg and Engel, Thomas}, title = {Single-layer Cuts for Multi-Layer Network Design Problems}, booktitle = {Telecommunications Modeling Policy and Technology, also ZIB Report ZR-07-21}, publisher = {Springer}, address = {College Park, MD, U.S.A.}, pages = {1 -- 23}, year = {2008}, language = {en} } @incollection{KosterOrlowskiRaacketal.2009, author = {Koster, Arie M.C.A. and Orlowski, Sebastian and Raack, Christian and Baier, Georg and Engel, Thomas and Belotti, Pietro}, title = {Branch-and-cut techniques for solving realistic two-layer network design problems}, booktitle = {Graphs and Algorithms in Communication Networks}, publisher = {Springer Berlin Heidelberg}, pages = {95 -- 118}, year = {2009}, language = {en} } @inproceedings{KosterKutschkaRaack2010, author = {Koster, Arie M.C.A. and Kutschka, Manuel and Raack, Christian}, title = {Towards Robust Network Design using Integer Linear Programming Techniques}, booktitle = {Proceedings of the NGI 2010, Paris, France}, publisher = {Next Generation Internet}, address = {Paris, France}, year = {2010}, language = {en} } @inproceedings{KosterRaack2009, author = {Koster, Arie M.C.A. and Raack, C.}, title = {A packing integer program arising in two-layer network design}, booktitle = {Proceedings of the INOC 2009, Pisa, Italy}, publisher = {International Network Optimization Conference}, address = {Pisa, Italy}, year = {2009}, language = {en} } @misc{ConiglioGrimmKosteretal.2015, author = {Coniglio, Stefano and Grimm, Boris and Koster, Arie M.C.A. and Tieves, Martin and Werner, Axel}, title = {Optimal offline virtual network embedding with rent-at-bulk aspects}, arxiv = {http://arxiv.org/abs/1501.07887}, pages = {9}, year = {2015}, abstract = {Network virtualization techniques allow for the coexistence of many virtual networks (VNs) jointly sharing the resources of an underlying substrate network. The Virtual Network Embedding problem (VNE) arises when looking for the most profitable set of VNs to embed onto the substrate. In this paper, we address the offline version of the problem. We propose a Mixed-Integer Linear Programming formulation to solve it to optimality which accounts for acceptance and rejection of virtual network requests, allowing for both splittable and unsplittable (single path) routing schemes. Our formulation also considers a Rent-at-Bulk (RaB) model for the rental of substrate capacities where economies of scale apply. To better emphasize the importance of RaB, we also compare our method to a baseline one which only takes RaB into account a posteriori, once a solution to VNE, oblivious to RaB, has been found. Computational experiments show the viability of our approach, stressing the relevance of addressing RaB directly with an exact formulation.}, language = {en} } @misc{KosterOrlowskiRaacketal.2007, author = {Koster, Arie M.C.A. and Orlowski, Sebastian and Raack, Christian and Bayer, Georg and Engel, Thomas}, title = {Single-layer Cuts for Multi-layer Network Design Problems}, issn = {1438-0064}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-9641}, number = {07-21}, year = {2007}, abstract = {We study a planning problem arising in SDH/WDM multi-layer telecommunication network design. The goal is to find a minimum cost installation of link and node hardware of both network layers such that traffic demands can be realized via grooming and a survivable routing. We present a mixed-integer programming formulation that takes many practical side constraints into account, including node hardware, several bitrates, and survivability against single physical node or link failures. This model is solved using a branch-and-cut approach with problem-specific preprocessing and cutting planes based on either of the two layers. On several realistic two-layer planning scenarios, we show that these cutting planes are still useful in the multi-layer context, helping to increase the dual bound and to reduce the optimality gaps.}, language = {en} } @misc{KosterKutschkaRaack2011, author = {Koster, Arie M.C.A. and Kutschka, Manuel and Raack, Christian}, title = {Robust Network Design: Formulations, Valid Inequalities, and Computations}, issn = {1438-0064}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-13890}, number = {11-34}, year = {2011}, abstract = {Traffic in communication networks fluctuates heavily over time. Thus, to avoid capacity bottlenecks, operators highly overestimate the traffic volume during network planning. In this paper we consider telecommunication network design under traffic uncertainty, adapting the robust optimization approach of Bertsimas and Sim [2004]. We present three different mathematical formulations for this problem, provide valid inequalities, study the computational implications, and evaluate the realized robustness. To enhance the performance of the mixed-integer programming solver we derive robust cutset inequalities generalizing their deterministic counterparts. Instead of a single cutset inequality for every network cut, we derive multiple valid inequalities by exploiting the extra variables available in the robust formulations. We show that these inequalities define facets under certain conditions and that they completely describe a projection of the robust cutset polyhedron if the cutset consists of a single edge. For realistic networks and live traffic measurements we compare the formulations and report on the speed up by the valid inequalities. We study the "price of robustness" and evaluate the approach by analyzing the real network load. The results show that the robust optimization approach has the potential to support network planners better than present methods.}, language = {en} }