TY - GEN A1 - Orlowski, Sebastian A1 - Wessäly, Roland T1 - An Integer Programming Model for Multi-Layer Network Design N2 - We present an integer linear programming model for the design of multi-layer telecommunication networks. The formulation integrates hardware, capacity, routing, and grooming decisions in \emph{any} n umber of network layers. Practical hardware restrictions and cost can accurately be taken into account for technologies based on connection-oriented routing protocols. T3 - ZIB-Report - 04-49 KW - multi-layer networks KW - integer programming KW - network design KW - routing KW - grooming Y1 - 2004 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-8248 ER - TY - GEN A1 - Kröller, Alexander A1 - Wessäly, Roland T1 - Integrated Optimization of Hardware Configuration and Capacity. Dimensioning in SDH and opaque WDM networks N2 - We suggest a new model for the design of telecommunication networks which integrates decisions about the topology, configuration of the switching hardware, link dimensioning, and protected routing of communication demands. Applying the branch-and-cut-algorithm implemented in our network planning and optimization tool DISCNET, we demonstrate that real-world based network planning instances of such an enhanced model can be solved. T3 - ZIB-Report - 03-49 KW - Survivable Network Design KW - Integer Programming KW - Hardware Configuration KW - Routing KW - Network Models KW - Network Planning KW - Resource Allocation KW - Surviva Y1 - 2003 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-7714 ER - TY - GEN A1 - Bley, Andreas A1 - Koch, Thorsten A1 - Wessäly, Roland T1 - Large-scale hierarchical networks: How to compute an optimal architecture? N2 - In this article, we present a mathematical model and an algorithm to support one of the central strategic planning decisions of network operators: How to organize a large number of locations into a hierarchical network? We propose a solution approach that is based on mixed-integer programming and Lagrangian relaxation techniques. As major advantage, our approach provides not only solutions but also worst-case quality guarantees. Real-world scenarios with more than 750 locations have been solved within 30 minutes to less than 1\% off optimality. T3 - ZIB-Report - 04-04 KW - Hierarchical Networks KW - Mixed-Integer Programming KW - Lagrangian Relaxation Y1 - 2004 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-7799 ER - TY - GEN A1 - Koch, Thorsten A1 - Wessäly, Roland T1 - Hierarchical Infrastructure Planning in Networks N2 - In this article, strategical infrastructure planning problems in the design of large-scale telecommunication networks are discussed based on experiences from three projects with industrial partners: The access network planning of the German Gigabit-Wissenschaftsnetz (G-WiN) for DFN (Verein zur Förderung eines Deutschen Forschungsnetzes e.V.), the mobile network switching center location planning project for E-Plus Mobilfunk, and the fixed network switching center location planning project for TELEKOM AUSTRIA. We introduce a mathematical model for a hierarchical multi-commodity capacitated facility location problem, present adaptions of this basic model to the specific requirements within the different projects and discuss the individual peculiarities and model decisions made. Eventually, we present and discuss computational results of three associated case studies, illustrating '"how we did the job`` with mathematical methods. T3 - ZIB-Report - 04-42 KW - Facility Location KW - Telecommunication KW - Mixed Integer Programming Y1 - 2004 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-8174 ER - TY - GEN A1 - Orlowski, Sebastian A1 - Koster, Arie M.C.A. A1 - Raack, Christian A1 - Wessäly, Roland T1 - Two-layer Network Design by Branch-and-Cut featuring MIP-based Heuristics N2 - This paper deals with MIP-based primal heuristics to be used within a branch-and-cut approach for solving multi-layer telecommunication network design problems. Based on a mixed-integer programming formulation for two network layers, we present three heuristics for solving important subproblems, two of which solve a sub-MIP. On multi-layer planning instances with many parallel logical links, we show the effectiveness of our heuristics in finding good solutions early in the branch-and-cut search tree. T3 - ZIB-Report - 06-47 KW - multi-layer network design KW - integer programming KW - branch-and-cut KW - heuristics Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-9412 ER - TY - GEN A1 - Hülsermann, Ralf A1 - Jäger, Monika A1 - Koster, Arie M.C.A. A1 - Orlowski, Sebastian A1 - Wessäly, Roland A1 - Zymolka, Adrian T1 - Availability and Cost Based Evaluation of Demand-wise Shared Protection N2 - In this paper, we investigate the connection availabilities for the new protection scheme Demand-wise Shared Protection (DSP) and describe an appropriate approach for their computation. The exemplary case study on two realistic network scenarios shows that in most cases the availabilities for DSP are comparable with that for 1+1 path protection and better than in case of shared path protection. T3 - ZIB-Report - 06-15 KW - demand-wise shared protection KW - network availability KW - network optimization Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-9080 ER - TY - GEN A1 - Gruber, Claus G. A1 - Koster, Arie M.C.A. A1 - Orlowski, Sebastian A1 - Wessäly, Roland A1 - Zymolka, Adrian T1 - A new model and a computational study for Demand-wise Shared Protection N2 - This report combines the contributions to INOC 2005 (Wessälly et al., 2005) and DRCN 2005 (Gruber et al., 2005). A new integer linear programming model for the end-to-end survivability concept deman d-wise shared protection (DSP) is presented. DSP is based on the idea that backup capacity is dedicated to a particular demand, but shared within a demand. It combines advantages of dedicated and shared protection: It is more cost-efficient than dedicated protection and operationally easier than shared protection. In a previous model for DSP, the number of working and backup paths to be configured for a particular demand has been an input parameter; in the more general model for DSP investigated in this paper, this value is part of the decisions to take. To use the new DSP model algorithmically, we suggest a branch-and-cut approach which employs a column generation procedure to deal with the exponential number of routing variables. A computational study to compare the new resilience mechanism DSP with dedicated and shared path protection is performed. The results for five realistic network planning scenarios reveal that the best solutions for DSP are on average 15\% percent better than the corresponding 1+1 dedicated path protection solutions, and only 15\% percent worse than shared path protection. T3 - ZIB-Report - 05-55 KW - demand-wise shared protection KW - resilience KW - network design KW - integer linear programming Y1 - 2005 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-8880 ER - TY - CHAP A1 - Eisenblätter, Andreas A1 - Koch, Thorsten A1 - Martin, Alexander A1 - Achterberg, Tobias A1 - Fügenschuh, Armin A1 - Koster, Arie M.C.A. A1 - Wegel, Oliver A1 - Wessäly, Roland ED - Anandalingam, G. ED - Raghavan, S. T1 - Modelling Feasible Network Configurations for UMTS T2 - Telecommunications Network Design and Management Y1 - 2003 UR - http://opus.kobv.de/zib/volltexte/2002/684/ PB - Kluver ER - TY - CHAP A1 - Bley, Andreas A1 - Koch, Thorsten A1 - Wessäly, Roland ED - Kaindl, H. T1 - Large-Scale hierarchical networks: How to compute an optimal architecture? T2 - Networks 2004 Y1 - 2004 SN - 3-8007-2840-0 SP - 429 EP - 434 PB - VDE Verlag CY - Berlin ER - TY - CHAP A1 - Koch, Thorsten A1 - Wessäly, Roland ED - Elmer, Carl-Friedrich ED - von Hirschhausen, Christian T1 - Hierarchical Infrastructure Planning in Networks T2 - Proceedings of the 3rd Conference on Applied Infrastructure Research, 9. October 2004, Berlin Y1 - 2004 UR - http://opus.kobv.de/zib/volltexte/2004/818/ ER - TY - GEN A1 - Alevras, Dimitris A1 - Grötschel, Martin A1 - Wessäly, Roland T1 - Cost-Efficient Network Synthesis from Leased Lines N2 - Given a communication demand between each pair of nodes of a network we consider the problem of deciding what capacity to install on each edge of the network in order to minimize the building cost of the network and to satisfy the demand between each pair of nodes. The feasible capacities that can be leased from a network provider are of a particular kind in our case. There are a few so-called basic capacities having the property that every basic capacity is an integral multiple of every smaller basic capacity. An edge can be equipped with a capacity only if it is an integer combination of the basic capacities. We treat, in addition, several restrictions on the routings of the demands (length restriction, diversification) and failures of single nodes or single edges. We formulate the problem as a mixed integer linear programming problem and develop a cutting plane algorithm as well as several heuristics to solve it. We report on computational results for real world data. T3 - ZIB-Report - SC-97-22 Y1 - 1997 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-2912 ER - TY - GEN A1 - Alevras, Dimitris A1 - Grötschel, Martin A1 - Wessäly, Roland T1 - Capacity and Survivability Models for Telecommunication Networks N2 - Designing low-cost networks that survive certain failure situations is one of the prime tasks in the telecommunication industry. In this paper we survey the development of models for network survivability used in practice in the last ten years. We show how algorithms integrating polyhedral combinatorics, linear programming, and various heuristic ideas can help solve real-world network dimensioning instances to optimality or within reasonable quality guarantees in acceptable running times. The most general problem type we address is the following. Let a communication demand between each pair of nodes of a telecommunication network be given. We consider the problem of choosing, among a discrete set of possible capacities, which capacity to install on each of the possible edges of the network in order to (i) satisfy all demands, (ii) minimize the building cost of the network. \noindent In addition to determining the network topology and the edge capacities we have to provide, for each demand, a routing such that (iii) no path can carry more than a given percentage of the demand, (iv) no path in the routing exceeds a given length. \noindent We also have to make sure that (v) for every single node or edge failure, a certain percentage of the demand is reroutable. \noindent Moreover, for all failure situations feasible routings must be computed. The model described above has been developed in cooperation with a German mobile phone provider. We present a mixed-integer programming formulation of this model and computational results with data from practice. T3 - ZIB-Report - SC-97-24 Y1 - 1997 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-2931 ER - TY - GEN A1 - Alevras, Dimitris A1 - Grötschel, Martin A1 - Jonas, Peter A1 - Paul, Ulrich A1 - Wessäly, Roland T1 - Survivable Mobile Phone Architectures: Models and Solution Methods N2 - In the highly competitive area of telecommunications, cost, quality, and network management are among the most important aspects to be considered when designing a network. We study the problem of dimensioning a telecommunication network that is still operating in case of a failure of a network component. Given a demand between each pair of nodes of a telecommunication network and a finite set of possible capacities for each edge of the network, we consider the problem of deciding what capacity to install on each edge of the network in order to minimize the building cost of the network and to satisfy the demand between each pair of nodes, even if a network component fails. The routing of the demands must satisfy the following additional restrictions: (a) there is a maximum number of nodes allowed in each path between any pair of nodes (path length restriction), and (b) there is a maximum percentage of the demand between each pair of nodes that can be routed through any network component (diversification restriction). Moreover, the chosen capacities must be such that, for every single node or single edge failure, a certain percentage of the demand between any pair of nodes is reroutable (i.e. it ``survives'' the particular failure). We formulate the problem as a mixed integer linear programming problem and present a cutting plane algorithm as well as several heuristics for its solution. Furthermore, we discuss several ways to implement survivability into a telecommunication network. T3 - ZIB-Report - SC-96-48 Y1 - 1996 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-2582 ER - TY - GEN A1 - Alevras, Dimitris A1 - Grötschel, Martin A1 - Wessäly, Roland T1 - A Network Dimensioning Tool N2 - Designing low cost networks that survive certain failure situations belongs to one of the prime tasks in the telecommunications industry. In this paper we describe a mathematical model combining several aspects of survivability that are elsewhere treated in a hierarchical fashion. We present mathematical investigations of this integrated model, a cutting plane algorithm, as well as several heuristics for its solution. Moreover, we report computational results with real world data. The problem we address is the following. Suppose, between each pair of nodes in a region, a communication demand is given. We want to determine the topology of a telecommunication network connecting the given nodes and to dimension all potential physical links. For each link, the possible capacities are restricted to a given finite set. The capacities must be chosen such that the communication demands are satisfied, even if certain network components fail, and such that the network building costs are as small as possible. Moreover, for each pair of nodes and each failure situation, we want to determine the paths on which the demand between the nodes is routed. T3 - ZIB-Report - SC-96-49 Y1 - 1996 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-2591 ER - TY - GEN A1 - Bley, Andreas A1 - Grötschel, Martin A1 - Wessäly, Roland T1 - Design of Broadband Virtual Private Networks: Model and Heuristics for the B–WiN N2 - We investigate the problem of designing survivable broadband virtual private networks that employ the Open Shortest Path First (OSPF) routing protocol to route the packages. The capacities available for the links of the network are a minimal capacity plus multiples of a unit capacity. Given the directed communication demands between all pairs of nodes, we wish to select the capacities in a such way, that even in case of a single node or a single link failure a specified percentage of each demand can be satisfied and the costs for these capacities are minimal. We present a mixed--integer linear programming formulation of this problem and several heuristics for its solution. Furthermore, we report on computational results with real-world data. T3 - ZIB-Report - SC-98-13 KW - Telecommunication Network Design KW - Survivable Networks KW - Network Capacity Planning KW - OSPF Routing KW - Shortest Path Routing KW - Heuristics Y1 - 1998 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-3565 ER -