QoS Restoration using a Disjoint Path Group in ATM Networks

Abstract A QoS restoration scheme for VP-based ATM network is proposed and its related characteristics are evaluated. The proposed scheme is a state-independent restoration scheme using a disjoint path group. A VP assignment and capacity planning problem using disjoint path group are formulated. When a failure occurs, failed working VPs are switched to protection paths with the same QoS level using a simple and fast restoration algorithm. The simulated restoration characteristics of the proposed algorithm are presented. A scheme of excess capacity assignment to protection path for dynamic traffic demands is also presented and analyzed

Multi-Hour, Multi-Traffic Class Network Design for Virtual Path-based Dynamically Reconfigurable Wide-Area ATM Networks

Virtual Path (VP) concept has been gaining attention in terms of effective deployment of ATM (Asynchronous Transfer Mode) networks in recent years. In a recent paper, we have outlined a framework and models for network design and management of dynamically reconfigurable ATM networks based on the virtual path concept from a network planning and management perspective. Our approach has been based on statistical multiplexing of traffic within a traffic class by using a virtual path for the class and deterministic multiplexing of different virtual paths, and on providing dynamic bandwidth and reconfigurability through virtual path concept depending on traffic load during the course of the day. In this paper, we discuss in detail a multi-hour, multi-traffic class network (capacity) design model for providing specified quality-of-service in such dynamically reconfigurable networks; this is done based on the observation that statistical multiplexing of virtual circuits for a traffic class in ..

A study of network for multi hour traffic under splittable and non splittable flow conditions

Title from PDF of title page, viewed on June 15, 2012Thesis advisor: Deep MedhiVitaIncludes bibliographic references (p. 139)Thesis (M.S.)--School of Computing and Engineering. University of Missouri--Kansas City, 2012In a multi hour networking environment, there are different traffic matrices operating during different time periods of the day depending on the demand. It is applicable to traffic networks such as IP networks or optical networks. In this work, we attempt to analyze how the different networking objectives relate to or differ from each other under multi hour traffic conditions. In particular, we have used three different objectives for our study, namely minimum cost routing, load balancing optimization (minimize link utilization) and minimize average delay. We consider them under both Splittable and non-Splittable flows. Our study focuses on considering three demand conditions: low load, moderate load, and high load. Besides the objectives as specified, we also consider the following indicators: (1) Number of non-zero paths to observe how the model behaves in terms of satisfying the demand, (2) Number of demands taking more than one path to observe how likely a model tries to spread the demand to more than one paths, (3) A distance measure, which represents the difference in path allotment between Splittable and non-Splittable cases to observe how closely related the models are with respect to satisfying a demand. Through an extensive study with four different network topologies and demand scenarios, we observe that the minimum cost routing model tries to use a single path to satisfy a demand as much as possible, while the minimizing average delay model shows the most tendency to split the demand and use more than one paths. For the load balancing model, once it chooses a set of paths, it retains those paths unless the problem becomes infeasible.Introduction -- Materials and methods -- Optimization models -- Results -- Pre analysis -- Conclusions -- Appendix A. Model files for the objective

Topological Design of Multiple Virtual Private Networks UTILIZING SINK-TREE PATHS

With the deployment of MultiProtocol Label Switching (MPLS) over a core backbone networks, it is possible for a service provider to built Virtual Private Networks (VPNs) supporting various classes of services with QoS guarantees. Efficiently mapping the logical layout of multiple VPNs over a service provider network is a challenging traffic engineering problem. The use of sink-tree (multipoint-to-point) routing paths in a MPLS network makes the VPN design problem different from traditional design approaches where a full-mesh of point-to-point paths is often the choice. The clear benefits of using sink-tree paths are the reduction in the number of label switch paths and bandwidth savings due to larger granularities of bandwidth aggregation within the network. In this thesis, the design of multiple VPNs over a MPLS-like infrastructure network, using sink-tree routing, is formulated as a mixed integer programming problem to simultaneously find a set of VPN logical topologies and their dimensions to carry multi-service, multi-hour traffic from various customers. Such a problem formulation yields a NP-hard complexity. A heuristic path selection algorithm is proposed here to scale the VPN design problem by choosing a small-but-good candidate set of feasible sink-tree paths over which the optimal routes and capacity assignments are determined. The proposed heuristic has clearly shown to speed up the optimization process and the solution can be obtained within a reasonable time for a realistic-size network. Nevertheless, when a large number of VPNs are being layout simultaneously, a standard optimization approach has a limited scalability. Here, the heuristics termed the Minimum-Capacity Sink-Tree Assignment (MCSTA) algorithm proposed to approximate the optimal bandwidth and sink-tree route assignment for multiple VPNs within a polynomial computational time. Numerical results demonstrate the MCSTA algorithm yields a good solution within a small error and sometimes yields the exact solution. Lastly, the proposed VPN design models and solution algorithms are extended for multipoint traffic demand including multipoint-to-point and broadcasting connections

Multi-layer traffic engineering in optical networks under physical layer impairments

Ankara : The Department of Electrical and Electronics Engineering and the Institute of Engineering and Sciences of Bilkent University, 2010.Thesis (Ph. D.) -- Bilkent University, 2010.Includes bibliographical references leaves 153-165.We study Traffic Engineering (TE) in Multiprotocol Label Switching (MPLS)/Wavelength Division Multiplexing (WDM) networks and propose a multi-layer TE method. MPLS provides powerful TE features for IP networks and is widely deployed in backbone networks. WDM can increase the transmission capacity of optical fibers to tremendous amounts, therefore it has been the dominant multiplexing technology used in the optical layer. The proposed multi-layer TE solution facilitates efficient use of network resources where the TE mechanisms in the MPLS and WDM layers coordinate. We consider a static WDM layer and available traffic expectation information. The TE problem arising in the considered scenario is the Virtual Topology Design (VTD) problem, which involves the decision of WDM lightpaths to be established, calculation of MPLS Label Switched Paths (LSPs) on the resulting virtual topology, and calculation of the routes and wavelengths in the physical topology that correspond to the lightpaths in the virtual topology. We assume a daily traffic pattern changing with the time of day and aim to design a static virtual topology that satisfies as much of the offered traffic as possible, over the whole day. In our proposed solution, the multi-layer VTD problem is solved by decomposing it into two sub-problems, each involving in a single layer. The decomposition approach is used in the thesis due to the huge computational burden of the combined solution for real-life networks. The sub-problem in the MPLS layer is the design of the lightpath topology and calculation of the LSP routes on this virtual topology. This problem is known to be NP-complete and finding its optimum solution is possible only for small networks. We propose a Tabu Search based heuristic method to solve two versions of this problem, resource oriented and performance oriented. Integer Linear Programming (ILP) relaxations are also developed for obtaining upper and lower bounds. We show that the gap between the produced solutions and the lower and upper bounds are around 10% and 7% for the resource and performance oriented problems, respectively. Since the actual traffic can show deviations from the expected values, we also developed an MPLS layer online TE method to compensate the instantaneous fluctuations of the traffic flows. In the proposed method, the LSPs are rerouted dynamically using a specially designed cost function. Our numerical studies show that using the designed cost function results in much lower blockings than using commonly used Widest Shortest Path First and Available Shortest Path First approaches in the literature. The corresponding sub-problem of the multi-layer VTD problem in the WDM layer is the Static Lightpath Establishment (SLE) problem. Along with the capacity and wavelength continuity constraints, we also consider the Bit Error Rate (BER) constraints due to physical layer impairments such as attenuation, polarization mode dispersion and switch crosstalk. This problem is NP-complete even without the BER constraints. We propose a heuristic solution method and develop an exact ILP formulation to evaluate the performance of the proposed method for small problem sizes. Our proposed method produces solutions close to the optimum solutions for the cases in which the ILP formulation could be solved to optimality. Then, these solution methods for the single layer sub-problems are combined in a multi-layer TE scheme to solve the VTD problem in both layers jointly. The proposed TE scheme considers the physical layer limitations and optical impairments. This TE scheme can be applied by keeping each layer’s information hidden from the other layer, but our simulations show that it can produce more effective and efficient solutions when the physical layer topology information is shared with the MPLS layer. We also investigate the effect of non-uniform optical components in terms of impairment characteristics. The numerical results show that more traffic can be routed when all the components in the network have moderate impairment characteristics, compared to the case in which some components have better and some have worse impairment characteristics.Şengezer, NamıkPh.D

Statistical analysis of network traffic for anomaly detection and quality of service provisioning

Network-wide traffic analysis and monitoring in large-scale networks is a challenging and expensive task. In this thesis work we have proposed to analyze the traffic of a large-scale IP network from aggregated traffic measurements, reducing measurement overheads and simplifying implementation issues. We have provided contributions in three different networking fields related to network-wide traffic analysis and monitoring in large-scale IP networks. The first contribution regards Traffic Matrix (TM) modeling and estimation, where we have proposed new statistical models and new estimation methods to analyze the Origin-Destination (OD) flows of a large-scale TM from easily available link traffic measurements. The second contribution regards the detection and localization of volume anomalies in the TM, where we have introduced novel methods with solid optimality properties that outperform current well-known techniques for network-wide anomaly detection proposed so far in the literature. The last contribution regards the optimization of the routing configuration in large-scale IP networks, particularly when the traffic is highly variable and difficult to predict. Using the notions of Robust Routing Optimization we have proposed new approaches for Quality of Service provisioning under highly variable and uncertain traffic scenarios. In order to provide strong evidence on the relevance of our contributions, all the methods proposed in this thesis work were validated using real traffic data from different operational networks. Additionally, their performance was compared against well-known works in each field, showing outperforming results in most cases. Taking together the ensemble of developed TM models, the optimal network-wide anomaly detection and localization methods, and the routing optimization algorithms, this thesis work offers a complete solution for network operators to efficiently monitor large-scale IP networks from aggregated traffic measurements and to provide accurate QoS-based performance, even in the event of volume traffic anomalie

Dimensionamento de redes ATM multi-serviço : modelos de programação linear inteira

Engenharia ElectrotécnicaEsta tese aborda o problema do dimensionamento de redes ATM (Asynchronous Transfer Mode) num cenário multi-serviço de suporte a serviços com diferentes características de tráfego: serviços conversacionais, serviços de consulta e serviços ponto-multiponto. O problema estudado considera a perspectiva de um operador de telecomunicações que tem como objectivo a determinação da rede física com o menor custo de operação e manutenção possível e que seja capaz de suportar o tráfego esperado para os diferentes serviços com a qualidade de serviço necessária. Os problemas de dimensionamento abordados consideram serviços comutados em que cada serviço é suportado por uma rede lógica constituída por VPCs (Virtual Path Connections) do tipo DBR (Deterministic Bit Rate) e o encaminhamento é fixo (uni-horário e multi-horário). O primeiro problema endereçado é o dimensionamento de redes ATM em que as redes lógicas de suporte a todos os tipos de serviços são constituídas exclusivamente por VPCs extremo-a-extremo. Esta arquitectura tem como principal vantagem a simplificação dos mecanismos de CAC (Call Admission Control) da rede. São propostos modelos de Programação Inteira para este problema. Os modelos desenvolvidos extendem modelos previamente conhecidos para serviços conversacionais de modo a poder ser considerado tráfego assimétrico (característico dos serviços de consulta e serviços pontomultiponto) e a modelização de VPCs em que um dos extremos não é conhecido à partida (característico dos serviços de consulta quando existem múltiplos servidores na rede). É proposto um algoritmo heurístico baseado na técnica da Relaxação Lagrangeana com Optimização por Sub-Gradiente para a resolução dos modelos desenvolvidos em redes de grande dimensão. No entanto, uma arquitectura baseada em VPCs extremo-a-extremo conduz a uma utilização pouco eficiente dos recursos da rede e, para redes de maiores dimensões, torna-se impraticável pelo elevado número de VPCs que exige. Como alternativa, são propostas duas arquitecturas diferentes. Para serviços conversacionais, é proposta uma arquitectura hierarquizada a 2 níveis para as redes lógicas de suporte. Esta arquitectura permite reduzir significativamente o número total de VPCs que é necessário configurar na rede sem contudo permitir que o número máximo de VPCs atravessados por cada ligação seja maior que três (um factor determinante para serviços comutados em que o tempo de estabelecimento de chamada é um parâmetro de qualidade de serviço a ter em consideração). Para serviços ponto-multiponto, é proposta uma arquitectura em árvore para as redes lógicas de suporte. São propostos modelos de Programação Inteira e Programação Inteira Mista para os problemas de dimensionamento da rede com as redes lógicas segundo as arquitecturas propostas. A resolução dos modelos propostos através de um algoritmo de branch-and-bound permite demonstrar que as arquitecturas alternativas propostas conduzem a ganhos significativos nos custos das redes obtidas quando comparados com os custos que se obtêm com redes lógicas baseadas em VPCs extremo-a-extremo

A flexible, abstract network optimisation framework and its application to telecommunications network design and configuration problems

A flexible, generic network optimisation framework is described. The purpose of this framework is to reduce the effort required to solve particular network optimisation problems. The essential idea behind the framework is to develop a generic network optimisation problem to which many network optimisation problems can be mapped. A number of approaches to solve this generic problem can then be developed. To solve some specific network design or configuration problem the specific problem is mapped to the generic problem and one of the problem solvers is used to obtain a solution. This solution is then mapped back to the specific problem domain. Using the framework in this way, a network optimisation problem can be solved using less effort than modelling the problem and developing some algorithm to solve the model. The use of the framework is illustrated in two separate problems: design of an enterprise network to accommodate voice and data traffic and configuration of a core diffserv/MPLS network. In both cases, the framework enabled solutions to be found with less effort than would be required if a more direct approach was used

Análisis estadístico del tráfico de red para la detección de anomalías y la calidad del servicio

Network-wide traffic analysis and monitoring in large-scale networks is a challenging and expensive task. In this thesis work we have proposed to analyze the traffic of a large-scale IP network from aggregated traffic measurements, reducing measurement overheads and simplifying implementation issues. We have provided contributions in three different networking fields related to network-wide traffic analysis and monitoring in large-scale IP networks. The first contribution regards Traffic Matrix (TM) modeling and estimation, where we have proposed new statistical models and new estimation methods to analyze the Origin-Destination (OD) flows of a large-scale TM from easily available link traffic measurements. The second contribution regards the detection and localization of volume anomalies in the TM, where we have introduced novel methods with solid optimality properties that outperform current well-known techniques for network-wide anomaly detection proposed so far in the literature. The last contribution regards the optimization of the routing configuration in large-scale IP networks, particularly when the traffic is highly variable and difficult to predict. Using the notions of Robust Routing Optimization we have proposed new approaches for Quality of Service provisioning under highly variable and uncertain traffic scenarios. In order to provide strong evidence on the relevance of our contributions, all the methods proposed in this thesis work were validated using real traffic data from different operational networks. Additionally, their performance was compared against well-known works in each field, showing outperforming results in most cases. Taking together the ensemble of developed TM models, the optimal network-wide anomaly detection and localization methods, and the routing optimization algorithms, this thesis work offers a complete solution for network operators to efficiently monitor large-scale IP networks from aggregated traffic measurements and to provide accurate QoS-based performance, even in the event of volume traffic anomalies.El monitoreo y el análisis del tráfico de red en redes de gran escala es una tarea costosa y desafiante. En este trabajo de tesis nos hemos propuesto analizar el tráfico de una red IP de gran escala a partir de mediciones de tráfico agregado, reducciendo gastos de monitoreo y simplificando problemas de implementación. Hemos obtenido resultados importantes en tres áreas diferentes relacionadas con el monitoreo y el análisis del tráfico de red en redes IP a gran escala. El primer resultado concierne el modelado y la estimación de la matriz de tráfico (TM), donde hemos propuesto nuevos modelos estadísticos y nuevos métodos de estimación para analizar la flujos Origen-Destino (OD) de una TM a gran escala, a partir de mediciones de volumen en los enlaces de red, fácilmente obtenibles en los sistemas de monitoreo de red de gran escala disponibles en la actualidad. El segundo aporte corresponde con la detección y localización automática de anomalías de volumen en la TM, donde hemos introducido nuevos métodos con sólidas propiedades de optimalidad y cuyo desempeño supera el de las técnicas actualmente propuestas en la literatura para detección de anomalías de red. La última contribución considera la optimización de la configuración del enrutamiento en redes IP a gran escala, especialmente cuando el tráfico en la red es altamente variable y difícil de predecir. Utilizando las nociones de optimización robusta del enrutamiento en la red, hemos propuesto nuevos enfoques para la provisión de calidad de servicio en escenarios donde el tráfico de red es altamente variable e incierto. Con el fin de proporcionar pruebas sólidas sobre la relevancia de nuestras contribuciones, todas los métodos propuestos en este trabajo de tesis han sido evaluados y validados utilizando mediciones de tráfico real en distintas redes operativas. Al mismo tiempo, su desempeño ha sido comparado contra el obtenido por técnicas bien conocidas en cada área, mostrando mejores resultados en la mayoría de los casos. Tomando el conjunto de técnicas desarrolladas respecto del modelado de la TM, la detección y localización óptima de anomalías de red, y los algoritmos de optimización robusta del enrutamineto en la red, este trabajo de tesis ofrece una solución completa para el monitoreo eficiente de redes IP de gran escala a partir de medidas de tráfico agregado, así como también un mecanismo automático para proporcionar niveles de calidad de servicio en caso de anomalías de tráfico