Ruiz Ramírez, Marc
Total activity: 36
Research group
GCO - Optical Communications Group
Department
Department of Computer Architecture
E-mail
mruizac.upc.edu
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1 to 36 of 36 results
  • Planning fixed to flexgrid gradual migration: drivers and open issues

     Ruiz Ramírez, Marc; Velasco Esteban, Luis; Lord, Andrew; Fonseca, Daniel; Pioro, Michal; Wessäly, Roland; Fernández-Palacios, Juan Pedro
    IEEE communications magazine
    Date of publication: 2014-01
    Journal article

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    Flexgrid technology has recently been presented as the most promising option for upgrading the currently operating fixed grid optical networks and extending their capacity to be able to deal with the massive traffic volumes forecast for the next decade. Although the current traffic is successfully supported on fixed grid networks, flexgrid technology brings features that are not offered by the fixed grid networks, such as transporting optical connections with a capacity beyond 100 Gb/s and elasticity against time-varying traffic. In light of this, a gradual fixed grid to flexgrid migration is generally accepted in order to add these useful features to the network. In this article, we study the migration process where flexgrid is deployed in the network progressively, and review the main drivers and open issues induced by its deployment.

  • Extending the flexgrid optical core towards the edges

     Velasco Esteban, Luis; Ruiz Ramírez, Marc; Castro Casales, Alberto; Comellas Colome, Jaume
    International Conference on Transparent Optical Networks
    Presentation of work at congresses

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    National IP/MPLS network have being designed on top of fixed-grid DWDM optical networks so to spread out covering large areas. Besides, multilayer IP/MPLS-over-DWDM networks take advantage from grooming to achieve high spectrum efficiency, filling the gap between users' flows and wavelength channels' capacity. The advent of the flexgrid technology providing a finer granularity makes possible to perform grooming also at the optical layer. We propose to flatten previous multilayer approaches and advance towards single layer networks consisting in a number of IP/MPLS areas connected through a flexgrid-based core network. A two-step procedure to design such flexgrid-based IP/MPLS national networks is proposed. In this paper, a future large flexgrid core network inter-connecting small areas is shown.

  • Impact of aggregation level on the performance of dynamic lightpath adaptation under time-varying traffic

     Asensio Carmona, Adrian; Klinkowski, Miroslaw; Ruiz Ramírez, Marc; Lopez, Victor Bohorquez; Castro Casales, Alberto; Velasco Esteban, Luis; Comellas Colome, Jaume
    International Conference on Optical Network Design and Modeling
    Presentation's date: 2013-04
    Presentation of work at congresses

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    In this article we focus on lightpath adaptation under time-varying traffic in a dynamic elastic optical network (EON) implementing flexgrid optical technology. In the considered scenario, a number of IP/MPLS metro area networks performing traffic aggregation are connected through a core EON. We explore the elastic spectrum allocation (SA) capability of EON and, in this context, we study the effectiveness of three alternative SA policies, namely Fixed, Semi-Elastic and Elastic. For each elastic SA policy, we develop a dedicated algorithm which is responsible for adaptation of spectrum allocated to lightpath connections in response to traffic changes. The evaluation is performed for a set of network scenarios, each one characterized by a different level of traffic aggregation, and hence different traffic variability. As simulation results show, the effectiveness of SA policies highly depends on both the aggregation level and maximum lightpath capacity. In particular, in our experiments up to 21% more traffic is served with the proposed elastic SA than with the fixed SA in a network with low aggregation and high lightpath capacity

    In this article we focus on lightpath adaptation under time-varying traffic in a dynamic elastic optical network (EON) implementing flexgrid optical technology. In the considered scenario, a number of IP/MPLS metro area networks performing traffic aggregation are connected through a core EON. We explore the elastic spectrum allocation (SA) capability of EON and, in this context, we study the effectiveness of three alternative SA policies, namely Fixed, Semi-Elastic and Elastic. For each elastic SA policy, we develop a dedicated algorithm which is responsible for adaptation of spectrum allocated to lightpath connections in response to traffic changes. The evaluation is performed for a set of network scenarios, each one characterized by a different level of traffic aggregation, and hence different traffic variability. As simulation results show, the effectiveness of SA policies highly depends on both the aggregation level and maximum lightpath capacity. In particular, in our experiments up to 21% more traffic is served with the proposed elastic SA than with the fixed SA in a network with low aggregation and high lightpath capacity.

  • Optimization models for flexgrid elastic optical networks

     Zotkiewicz, Mateusz; Pioro, Michal; Ruiz Ramírez, Marc; Klinkowski, Miroslaw; Velasco Esteban, Luis
    International Conference on Transparent Optical Networks
    Presentation's date: 2013-06
    Presentation of work at congresses

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    In the paper we present integer programming (IP) optimization models for flexgrid elastic optical networks (EON). We consider several different basic assumptions regarding flexibility of EON that lead to a variety of IP formulations differing in precision and complexity. As usual, detailed models aiming at precisely describing technological aspects of EON suffer from tractability issues resulting from their greater complexity and have to be reasonably simplified. To achieve this, we consider cases where the bandwidth is divided into predefined slots, cases where the bandwidth is continuous and can be divided between demands with no restrictions, cases where a list of predefined paths is available, and finally cases where all the paths are indirectly taken into account. We present both compact and non-compact formulations. The non-compact formulations are accompanied with brief description of the dedicated column generation algorithms.

  • A traffic intensity model for flexgrid optical network planning under dynamic traffic operation

     Ruiz Ramírez, Marc; Velasco Esteban, Luis; Comellas Colome, Jaume; Junyent Giralt, Gabriel
    Optical Fiber Communication Conference and Exposition and National Fiber Optic Engineers Conference
    Presentation's date: 2013-03
    Presentation of work at congresses

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    We obtain a model to estimate the highest traffic intensity that a flexgrid-based network can support in dynamic scenarios. A design problem is introduced to illustrate its application. Numerical results validate both accuracy and utility.

  • A column generation approach for large-scale RSA-based network planning

     Ruiz Ramírez, Marc; Zotkiewicz, Mateusz; Velasco Esteban, Luis; Comellas Colome, Jaume
    International Conference on Transparent Optical Networks
    Presentation's date: 2013-06
    Presentation of work at congresses

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    In flexgrid-based optical networks, the problem of finding optimal route and spectrum allocation (RSA) for the demands in a traffic matrix becomes harder to solve than similar problems in fixed DWDM networks, mainly due to the finer spectrum granularity and the spectrum contiguity and continuity constraints. Additionally, the increasing traffic volumes and the size of real networks lead to network planning problem instances consisting of hundreds of thousands, or even millions, of (binary) variables. In this work, we present a column generation decomposition method to obtain feasible solutions for RSA-based network planning problems. Numerical results show the utility of this method for solving intractable instances.

  • Solving routing and spectrum allocation related optimization problems

     Velasco Esteban, Luis; Castro Casales, Alberto; Ruiz Ramírez, Marc
    European Conference and Exhibition on Optical Communication
    Presentation's date: 2013-09
    Presentation of work at congresses

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    We provide a comprehensible introduction to RSA-related problems in flexgrid networks. Starting from its formulation, we analyze network live cycle and indicate different solving methods for the kind of problems that arise at each network phase: from the initial network planning to network re-optimization, going through network operation.

  • A GRASP with path-relinking heuristic for the survivable IP/MPLS-over-WSON multi-layer network optimization problem

     Pedrola Escriba, Oscar; Ruiz Ramírez, Marc; Velasco Esteban, Luis; Careglio, Davide; Gonzalez de Dios, Oscar; Comellas Colome, Jaume
    Computers & operations research
    Date of publication: 2013-12
    Journal article

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    In this paper we deal with the survivable internet protocol (IP)/multi-protocol label switching (MPLS)-over-wavelength switched optical network (WSON) multi-layer network optimization problem (SIMNO). This problem entails planning an IP/MPLS network layer over a photonic mesh infrastructure whilst, at the same time, ensuring the highest availability of services and minimizing the capital expenditures (CAPEX) investments. Such a problem is currently identified as an open issue among network operators, and hence, its solution is of great interest. To tackle SIMNO, we first provide an integer linear programming (ILP) formulation which provides an insight into the complexity of its managing. Then, a greedy randomized adaptive search procedure (GRASP) with path-relinking (PR) together with a biased random-key genetic algorithm (BRKGA) are specifically developed to help solve the problem. The performance of both heuristics is exhaustively tested and compared making use of various network and traffic instances. Numerical experiments show the benefits of using GRASP instead of BRKGA when dealing with highly complex network scenarios. Moreover, we verified that the use of GRASP with PR remarkably improves the basic GRASP algorithm, particularly in real-sized, complex scenarios such as those proposed in this paper.

    In this paper we deal with the survivable internet protocol (IP)/multi-protocol label switching (MPLS)-over-wavelength switched optical network (WSON) multi-layer network optimization problem (SIMNO). This problem entails planning an IP/MPLS network layer over a photonic mesh infrastructure whilst, at the same time, ensuring the highest availability of services and minimizing the capital expenditures (CAPEX) investments. Such a problem is currently identified as an open issue among network operators, and hence, its solution is of great interest. To tackle SIMNO, we first provide an integer linear programming (ILP) formulation which provides an insight into the complexity of its managing. Then, a greedy randomized adaptive search procedure (GRASP) with path-relinking (PR) together with a biased random-key genetic algorithm (BRKGA) are specifically developed to help solve the problem. The performance of both heuristics is exhaustively tested and compared making use of various network and traffic instances. Numerical experiments show the benefits of using GRASP instead of BRKGA when dealing with highly complex network scenarios. Moreover, we verified that the use of GRASP with PR remarkably improves the basic GRASP algorithm, particularly in real-sized, complex scenarios such as those proposed in this paper.

  • Column generation algorithm for RSA problems in flexgrid optical networks

     Ruiz Ramírez, Marc; Pioro, Michal; Zotkiewicz, Mateusz; Klinkowski, Miroslaw; Velasco Esteban, Luis
    Photonic network communications
    Date of publication: 2013-10
    Journal article

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    Finding optimal routes and spectrum allocation in flexgrid optical networks, known as the RSA problem, is an important design problem in transport communication networks. The problem is NP-hard, and its intractability becomes profound when network instances with several tens of nodes and several hundreds of demands are to be solved to optimum. In order to deal with such instances, large-scale optimization methods need to be considered. In this work, we present a column (more precisely, path) generation-based method for the RSA problem. The method is capable of finding reasonable sets of lightpaths, avoiding large sets of precomputed paths, and leading to high-quality solutions. Numerical results illustrating effectiveness of the proposed method for obtaining solutions for large RSA problem instances are presented.

  • Elastic spectrum allocation for time-varying traffic in flexgrid optical networks

     Klinkowski, Miroslaw; Ruiz Ramírez, Marc; Velasco Esteban, Luis; Careglio, Davide; López Álvarez, Victor; Comellas Colome, Jaume
    IEEE journal on selected areas in communications
    Date of publication: 2013-01
    Journal article

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  • Design of green optical networks with signal quality guarantee

     Cavdar, Cicek; Ruiz Ramírez, Marc; Monti, Paolo; Velasco Esteban, Luis; Wosinska, Lena
    IEEE International Conference on Communications
    Presentation's date: 2012-06
    Presentation of work at congresses

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  • Path-based recovery in flexgrid optical networks

     Castro Casales, Alberto; Ruiz Ramírez, Marc; Velasco Esteban, Luis; Junyent Giralt, Gabriel; Comellas Colome, Jaume
    International Conference on Transparent Optical Networks
    Presentation's date: 2012
    Presentation of work at congresses

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    With the advent of flexgrid optical networks, the rigid wavelength-division multiplexing (WDM) technology will be enhanced by providing better spectrum efficiency and flexibility. In those future flexible optical networks, optical connections (lightpaths) can allocate a flexible number of spectrum slices, also known as frequency slots, so to match better with its requested bitrate. In this paper, we propose to take advantage of this flexible spectrum allocation in recovery mechanisms to be triggered when a failure occurs to provide recovery of part of the requested bitrate, i.e. the allocated spectrum by backup lightpaths could be lower than that of the working lightpaths provided that client service level agreements are fulfilled. This reduction in the recovered bitrate (bitrate squeezing) allows optimizing the use of network capacity. We propose path-based recovery alternatives, based on protection and restoration, specially designed for flexgrid networks. The performance of the proposed recovery mechanisms is exhaustively evaluated on a national reference network

  • On the performance of flexgrid-based optical networks

     Velasco Esteban, Luis; Ruiz Ramírez, Marc; Pedrola Escriba, Oscar; Castro Casales, Alberto; Klinkowski, Miroslaw; Careglio, Davide; Comellas Colome, Jaume
    International Conference on Transparent Optical Networks
    Presentation's date: 2012-07
    Presentation of work at congresses

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  • Elastic spectrum allocation for variable traffic in flexible-grid optical networks

     Velasco Esteban, Luis; Klinkowski, Miroslaw; Ruiz Ramírez, Marc; López Álvarez, Victor; Junyent Giralt, Gabriel
    Optical Fiber Communication Conference and Exposition and National Fiber Optic Engineers Conference
    Presentation's date: 2012-03
    Presentation of work at congresses

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  • Single-path provisioning with multi-path recovery in flexgrid optical networks

     Castro Casales, Alberto; Velasco Esteban, Luis; Ruiz Ramírez, Marc; Comellas Colome, Jaume
    International Congress on Ultra Modern Telecommunications and Control Systems and Workshops
    Presentation's date: 2012-05-03
    Presentation of work at congresses

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    The new flexgrid technology, in opposition to the fixed grid one traditionally used in wavelength switched optical networks (WSON), allows allocating the spectral bandwidth needed to convey heterogeneous client demand bitrates in a flexible manner so that the optical spectrum can be managed much more efficiently. In this paper we propose a new recovery scheme, called single-path provisioning multi-path recovery (SPP-MPR), specifically designed for flexgrid-based optical networks. It provisions single-paths to serve the bitrate requested by client demands and combines protection and restoration schemes to jointly recover, in part or totally, that bitrate in case of failure. We define the bitrate squeezed recovery optimization (BRASERO) problem to maximize the bitrate which is recovered in case of failure of any single fiber link. A mixed integer linear programming (MILP) formulation is provided. Exhaustive numerical experiments carried out over two network topologies and realistic traffic scenarios show that the efficiency of the proposed SPP-MPR scheme approaches that of restoration mechanisms while providing recovery times as short as protection schemes.

  • Modeling the routing and spectrum allocation problem for flexgrid optical networks

     Velasco Esteban, Luis; Klinkowski, Miroslaw; Ruiz Ramírez, Marc; Comellas Colome, Jaume
    Photonic network communications
    Date of publication: 2012-12
    Journal article

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  • Dynamic routing and spectrum (re)allocation in future flexgrid optical networks

     Castro Casales, Alberto; Velasco Esteban, Luis; Ruiz Ramírez, Marc; Klinkowski, Miroslaw; Fernández Palacios, Juan Pedro; Careglio, Davide
    Computer networks
    Date of publication: 2012-08-16
    Journal article

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  • Characterization, Design and Re-optimization on Multi-layer Optical Networks  Open access

     Ruiz Ramírez, Marc
    Defense's date: 2012-12-21
    Department of Computer Architecture, Universitat Politècnica de Catalunya
    Theses

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    L'augment de volum de tràfic IP provocat per l'increment de serveis multimèdia com HDTV o vídeo conferència planteja nous reptes als operadors de xarxa per tal de proveir transmissió de dades eficient. Tot i que les xarxes mallades amb multiplexació per divisió de longitud d'ona (DWDM) suporten connexions òptiques de gran velocitat, aquestes xarxes manquen de flexibilitat per suportar tràfic d’inferior granularitat, fet que provoca un pobre ús d'ample de banda. Per fer front al transport d'aquest tràfic heterogeni, les xarxes multicapa representen la millor solució. Les xarxes òptiques multicapa permeten optimitzar la capacitat mitjançant l'empaquetament de connexions de baixa velocitat dins de connexions òptiques de gran velocitat. Durant aquesta operació, es crea i modifica constantment una topologia virtual dinàmica gràcies al pla de control responsable d’aquestes operacions. Donada aquesta dinamicitat, un ús sub-òptim de recursos pot existir a la xarxa en un moment donat. En aquest context, una re-optimizació periòdica dels recursos utilitzats pot ser aplicada, millorant així l'ús de recursos. Aquesta tesi està dedicada a la caracterització, planificació, i re-optimització de xarxes òptiques multicapa de nova generació des d’un punt de vista unificat incloent optimització als nivells de capa física, capa òptica, capa virtual i pla de control. Concretament s'han desenvolupat models estadístics i de programació matemàtica i meta-heurístiques. Aquest objectiu principal s'ha assolit mitjançant cinc objectius concrets cobrint diversos temes oberts de recerca. En primer lloc, proposem una metodologia estadística per millorar el càlcul del factor Q en problemes d'assignació de ruta i longitud d'ona considerant interaccions físiques (IA-RWA). Amb aquest objectiu, proposem dos models estadístics per computar l'efecte XPM (el coll d'ampolla en termes de computació i complexitat) per problemes IA-RWA, demostrant la precisió d’ambdós models en el càlcul del factor Q en escenaris reals de tràfic. En segon lloc i fixant-nos a la capa òptica, presentem un nou particionament del conjunt de longituds d'ona que permet maximitzar, respecte el cas habitual, la quantitat de tràfic extra proveït en entorns de protecció compartida. Concretament, definim diversos models estadístics per estimar la quantitat de tràfic donat un grau de servei objectiu, i diferents models de planificació de xarxa amb l'objectiu de maximitzar els ingressos previstos i el valor actual net de la xarxa. Després de resoldre aquests problemes per xarxes reals, concloem que la nostra proposta maximitza ambdós objectius. En tercer lloc, afrontem el disseny de xarxes multicapa robustes davant de fallida simple a la capa IP/MPLS i als enllaços de fibra. Per resoldre aquest problema eficientment, proposem un enfocament basat en sobre-dimensionar l'equipament de la capa IP/MPLS i recuperar la connectivitat i el comparem amb la solució convencional basada en duplicar la capa IP/MPLS. Després de comparar solucions mitjançant models ILP i heurístiques, concloem que la nostra solució permet obtenir un estalvi significatiu en termes de costos de desplegament. Com a quart objectiu, introduïm un mecanisme adaptatiu per reduir l'ús de ports opto-electrònics (O/E) en xarxes multicapa sota escenaris de tràfic dinàmic. Una formulació ILP i diverses heurístiques són desenvolupades per resoldre aquest problema, que permet reduir significativament l’ús de ports O/E en temps molt curts. Finalment, adrecem el problema de disseny resilient del pla de control GMPLS. Després de proposar un nou model analític per quantificar la resiliència en topologies mallades de pla de control, usem aquest model per proposar un problema de disseny de pla de control. Proposem un procediment iteratiu lineal i una heurística i els usem per resoldre instàncies reals, arribant a la conclusió que es pot reduir significativament la quantitat d'enllaços del pla de control sense afectar la qualitat de servei a la xarxa.

    The explosion of IP traffic due to the increase of IP-based multimedia services such as HDTV or video conferencing poses new challenges to network operators to provide a cost-effective data transmission. Although Dense Wavelength Division Multiplexing (DWDM) meshed transport networks support high-speed optical connections, these networks lack the flexibility to support sub-wavelength traffic leading to poor bandwidth usage. To cope with the transport of that huge and heterogeneous amount of traffic, multilayer networks represent the most accepted architectural solution. Multilayer optical networks allow optimizing network capacity by means of packing several low-speed traffic streams into higher-speed optical connections (lightpaths). During this operation, a dynamic virtual topology is created and modified the whole time thanks to a control plane responsible for the establishment, maintenance, and release of connections. Because of this dynamicity, a suboptimal allocation of resources may exist at any time. In this context, a periodically resource reallocation could be deployed in the network, thus improving network resource utilization. This thesis is devoted to the characterization, planning, and re-optimization of next-generation multilayer networks from an integral perspective including physical layer, optical layer, virtual layer, and control plane optimization. To this aim, statistical models, mathematical programming models and meta-heuristics are developed. More specifically, this main objective has been attained by developing five goals covering different open issues. First, we provide a statistical methodology to improve the computation of the Q-factor for impairment-aware routing and wavelength assignment problems (IA-RWA). To this aim we propose two statistical models to compute the Cross-Phase Modulation variance (which represents the bottleneck in terms of computation time and complexity) in off-line and on-line IA-RWA problems, proving the accuracy of both models when computing Q-factor values in real traffic scenarios. Second and moving to the optical layer, we present a new wavelength partitioning scheme that allows maximizing the amount of extra traffic provided in shared path protected environments compared with current solutions. Specifically, we define several statistical models to estimate the traffic intensity given a target grade of service, and different network planning problems for maximizing the expected revenues and net present value. After solving these problems for real networks, we conclude that our proposed scheme maximizes both revenues and NPV. Third, we tackle the design of survivable multilayer networks against single failures at the IP/MPLS layer and WSON links. To efficiently solve this problem, we propose a new approach based on over-dimensioning IP/MPLS devices and lightpath connectivity and recovery and we compare it against the conventional solution based on duplicating backbone IP/MPLS nodes. After evaluating both approaches by means of ILP models and heuristic algorithms, we conclude that our proposed approach leads to significant CAPEX savings. Fourth, we introduce an adaptive mechanism to reduce the usage of opto-electronic (O/E) ports of IP/MPLS-over-WSON multilayer networks in dynamic scenarios. A ILP formulation and several heuristics are developed to solve this problem, which allows significantly reducing the usage of O/E ports in very short running times. Finally, we address the design of resilient control plane topologies in GMPLS-enabled transport networks. After proposing a novel analytical model to quantify the resilience in mesh control plane topologies, we use this model to propose a problem to design the control plane topology. An iterative model and a heuristic are proposed and used to solve real instances, concluding that a significant reduction in the number of control plane links can be performed without affecting the quality of service of the network.

  • Industry-Driven Elastic and Adaptive Lambda Infrastructure for Service and Transport Networks

     Ruiz Ramírez, Marc; Castro Casales, Alberto; Comellas Colome, Jaume; Junyent Giralt, Gabriel; Gifre Renom, Lluis; Velasco Esteban, Luis
    Participation in a competitive project

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  • Enhanced optical networks featuring adaptable and highly scalable multi-granular transport services

     Ruiz Ramírez, Marc; Junyent Giralt, Gabriel; Comellas Colome, Jaume; Gené Bernaus, Joan M.; Conesa Fernandez, Josep; Velasco Esteban, Luis; Perello Muntan, Jordi; Agraz Bujan, Fernando; Hernandez Sola, Guillem; Pages Cruz, Albert; Khodashenas, Pooria Saiyad; Spadaro, Salvatore
    Participation in a competitive project

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  • CAPEX study for a multilayer IP/MPLS-over-flexgrid optical network

     Pedrola Escriba, Oscar; Castro Casales, Alberto; Velasco Esteban, Luis; Ruiz Ramírez, Marc; Careglio, Davide
    Journal of optical communications and networking
    Date of publication: 2012-08
    Journal article

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  • A linearized statistical XPM model for accurate Q-factor computation

     Ruiz Ramírez, Marc; Velasco Esteban, Luis; Monti, Paolo; Wosinska, Lena
    IEEE communications letters
    Date of publication: 2012
    Journal article

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  • Statistical approach for fast impairment-aware provisioning in dynamic all-optical networks

     Velasco Esteban, Luis; Jirattigalachote, Amo; Ruiz Ramírez, Marc; Monti, Paolo; Wosinska, Lena; Junyent Giralt, Gabriel
    Journal of optical communications and networking
    Date of publication: 2012-02
    Journal article

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  • Optical network net present value optimization in shared path protection environments

     Ruiz Ramírez, Marc; Velasco Esteban, Luis; Comellas Colome, Jaume; Junyent Giralt, Gabriel
    Design of Reliable Communication Networks
    Presentation's date: 2011-10-10
    Presentation of work at congresses

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    Network operators are facing hard competition for opportunities in the telecommunications market, thus network investments must be carefully evaluated from the costs and revenues viewpoint before the decision making process. Since a great part of core network operators’ revenues comes from the provisioned connectivity services, in this work we study the value expected to generate by optical networks when provisioning differentiated services in Shared Path Protection (SPP) environments. In this regard, two wavelength partitioning schemes are compared: the shared (sh-WS) and the differentiated (diff-WS). The benefits of both schemes are evaluated from an economic perspective defining costs and revenues models and using Net Present Value (NPV). We define the Optical Network NPV Optimization (OVALO) problem as a NPV maximization problem. To solve OVALO, a linearized version of NPV is proposed as objective function of the Integer Linear Programming (ILP) model and an iterative algorithm is used to finally solve OVALO. The partitioning schemes are numerically compared on two network topologies. From the results, we show that diff-WS maximizes resource utilization in the network without significantly increasing network costs, thus maximizing the network’s value.

  • NORMA: Network Operator Revenues Maximization

     Velasco Esteban, Luis; Ruiz Ramírez, Marc; Comellas Colome, Jaume; Junyent Giralt, Gabriel
    International Conference on Transparent Optical Networks
    Presentation's date: 2011-05-27
    Presentation of work at congresses

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    A great part of core network operators’ gross profit comes from the provisioned connectivity services. In this work, we analyze the provisioning of differentiated services in current Shared Path Protection (SPP) environments. This analysis concludes that, with current resource assignment policies, only a very poor grade of service can be provided to the carried best effort traffic. Hence, we propose diff-WS, a resource partitioning scheme that differentiates those wavelengths supporting each class of service in the network. The benefits of diff-WS in front of current resource assignment policies are afterwards evaluated from an economic perspective. To this goal, we define the NORMA problem as a revenue maximization problem. To solve NORMA, we introduce statistical models to obtain, for a given grade of service, the highest traffic intensity for each supported class of service and resource assignment scheme. From the numerical results, we show that diff-WS maximizes resource utilization in the network and, thus, network operator’s profit.

  • A GRASP-based heuristic to design the GMPLS control plane network topology with resilience guarantees

     Ruiz Ramírez, Marc; Velasco Esteban, Luis; Junyent Giralt, Gabriel; Comellas Colome, Jaume
    International Conference on Transparent Optical Networks
    Presentation's date: 2011-06-28
    Presentation of work at congresses

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    The control plane topology has traditionally followed that of the data plane and therefore the design of the former, as well as its resilience, has been addressed in the latter's one. Owing to the fact that a clear separation between control and data planes is a main GMPLS architectural requirement, the control plane in GMPLS networks may describe a different topology than the data plane, even realized over a separated IP network. As a consequence of this, data and control network design become no more linked in such scenarios. In this paper, we design a heuristic algorithm to obtain the optimal GMPLS control plane design, minimizing the network Capital Expenditures (CAPEX) while matching specific resilience requirements. The performance of the heuristic algorithm is compared with exact solutions obtained by solving an Integer Linear Programming (ILP) model on several reference network scenarios. Furthermore, its benefits in terms of total execution time are also highlighted.

  • GMPLS control plane network design with resilience guarantees

     Ruiz Ramírez, Marc; Perello Muntan, Jordi; Velasco Esteban, Luis; Spadaro, Salvatore; Comellas Colome, Jaume; Junyent Giralt, Gabriel
    Journal of lightwave technology
    Date of publication: 2011-01-01
    Journal article

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    A one-to-one association between data and control channels has traditionally existed in transport networks. Being the control plane embedded in the data plane, the design of the former, as well as its resilience, has been addressed in the latter’s one. However, a main GMPLS architectural requirement is to provide a clean separation between control and data planes. In this sense, the control plane in GMPLS networks may describe a different topology than the data plane, even realized over a separated IP network. As a consequence of this, data and control network design become no more linked in such scenarios. To the best of our knowledge, no works in the literature have addressed an independent design of the control plane in GMPLS-enabled networks regardless of the data plane. In this paper, we provide a method to obtain the optimal GMPLS control plane design, minimizing the network Capital Expenditures (CAPEX) while matching specific resilience requirements. To this goal, the problem of finding an optimal control plane topology that ensures a certain resilience level is formulated as a non-linear combinatorial model. This model, however, does not scale properly for large backbone networks. In view of this, a constructive linear method is also presented and its optimality validated through simulations on several reference network scenarios. Furthermore, its benefits in terms of total execution time are also highlighted.

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    Service and resource differentiation in shared-path protection environments to maximize network operator's revenues  Open access

     Velasco Esteban, Luis; Ruiz Ramírez, Marc; Perello Muntan, Jordi; Spadaro, Salvatore; Comellas Colome, Jaume
    Journal of optical communications and networking
    Date of publication: 2011-02
    Journal article

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    Network operators are facing hard competition for opportunities in the telecommunications market, forcing network investments to be carefully evaluated before the decision-making process. A great part of core network operators’ revenues comes from the provisioned connectivity services. Taking this premise as our starting point, we first examine the provisioning of differentiated services in current shared-path protection (SPP) environments. This analysis reveals that current resource assignment policies are only able to provide a very poor grade of service to the supported best-effort traffic. Aiming to improve this performance, a novel resource partitioning scheme called diff-WS is proposed, which differentiates those wavelengths supporting each class of service in the network. As a major goal of this paper, the benefits of diff-WS over current resource assignment policies are assessed from an economic perspective. For this purpose, the network operator revenues maximization (NORMA) problem is presented to design the optical network such that the operator’s revenues are maximized. To solve NORMA, we derive statistical models to obtain, given a certain grade of service, the highest traffic intensity for each class of service and resource partitioning scheme. These models turn NORMA into a nonlinear problem, which is finally addressed as an iterative approach, solving an integer linear programming (ILP) subproblem at each iteration. The obtained numerical results on several network topologies illustrate that diff-WS maximizes resource utilization in the network and, thus, the network operator’s profit.

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    Survivable IP/MPLS-Over-WSON multilayer network optimization  Open access

     Ruiz Ramírez, Marc; Pedrola Escriba, Oscar; Velasco Esteban, Luis; Careglio, Davide; Fernández Palacios, Juan Pedro; Junyent Giralt, Gabriel
    Journal of optical communications and networking
    Date of publication: 2011-08-01
    Journal article

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    Network operators are facing the problem of dimensioning their networks for the expected huge IP traffic volumes while keeping constant or even reducing the connectivity prices. Therefore, new architectural solutions able to cope with the expected traffic increase in a more cost-effective way are needed. In this work, we study the survivable IP/multi-protocol label switching (MPLS) over wavelength switched optical network (WSON) multilayer network problem as a capital expenditure (CAPEX) minimization problem. Two network approaches providing survivability against optical links, IP/MPLS nodes, and opto-electronic port failures are compared: the classical overlay approach where two redundant IP/MPLS networks are deployed, and the new joint multilayer approach which provides the requested survivability through an orchestrated interlayer recovery scheme which minimizes the over-dimensioning of IP/MPLS nodes. Mathematical programming models are developed for both approaches. Solving these models, however, becomes impractical for realistic networks. In view of this, evolutionary heuristics based on the biased random-key genetic algorithm framework are also proposed. Exhaustive experiments on several reference network scenarios illustrate the effectiveness of the proposed approach in minimizing network CAPEX.

  • Deployment and validation of GMPLS-controlled multi-layer integrated routing over the ASON/GMPLS CARISMA test-bed

     Agraz Bujan, Fernando; Velasco Esteban, Luis; Perello Muntan, Jordi; Ruiz Ramírez, Marc; Spadaro, Salvatore; Junyent Giralt, Gabriel; Comellas Colome, Jaume
    Journal of networks
    Date of publication: 2010-11
    Journal article

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  • Maximización del valor actual neto en redes ópticas

     Velasco Esteban, Luis; Ruiz Ramírez, Marc; Cid Mena, Cecilia
    Date of publication: 2010-06-01
    Book

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  • Resources optimization in GMPLS-based optical multilayer networks

     Ruiz Ramírez, Marc; Velasco Esteban, Luis; Spadaro, Salvatore; Comellas Colome, Jaume; Junyent Giralt, Gabriel
    European Conference on Networks and Optical Communications
    Presentation's date: 2009-06-12
    Presentation of work at congresses

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    An experimental GMPLS-controlled network test-bed enabling sub-wavelength connection provisioning  Open access

     Agraz Bujan, Fernando; Velasco Esteban, Luis; Perello Muntan, Jordi; Ruiz Ramírez, Marc; Spadaro, Salvatore; Junyent Giralt, Gabriel; Comellas Colome, Jaume
    International Conference on Transparent Optical Networks
    Presentation's date: 2009-06-20
    Presentation of work at congresses

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    The efficient accommodation of sub-wavelength client flows on optical channels is a current challenge for resources use optimization in GMPLS controlled optical networks. While optical channels capacity usually exceeds 10 Gbit/s, client connections requests show finer granularity. This paper concentrates on the design and implementation of a GMPLS-controlled grooming capable transport infrastructure on the ASON/GMPLS CARISMA test-bed. Through the paper, the operation of a GMPLS-controlled multi-layer network architecture is introduced, subsequently highlighting implementation issues that come into light. The contributions proposed in the paper are supported by illustrative experimental results.

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    An analytical model for GMPLS control plane resilience quantification  Open access

     Ruiz Ramírez, Marc; Perello Muntan, Jordi; Velasco Esteban, Luis; Spadaro, Salvatore; Comellas Colome, Jaume
    IEEE communications letters
    Date of publication: 2009-12
    Journal article

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    This paper concentrates on the resilience of the Generalized Multi-Protocol Label Switching (GMPLS) enabled control plane. To this end, the problem of control plane resilience in GMPLS-controlled networks is firstly stated and previous work on the topic reviewed. Next, analytical formulae to quantify the resilience of generic meshed control plane topologies are derived. The resulting model is validated by simulation results on several reference network scenarios.

  • ENGINEERING NEXT GENERATION OPTICAL TRANSPORT NETWORKS

     Junyent Giralt, Gabriel; Gené Bernaus, Joan M.; Velasco Esteban, Luis; Comellas Colome, Jaume; Conesa Fernandez, Josep; Perello Muntan, Jordi; Ruiz Ramírez, Marc; Spadaro, Salvatore
    Participation in a competitive project

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    Design and implementation of a GMPLS-controlled grooming-capable optical transport network  Open access

     Agraz Bujan, Fernando; Velasco Esteban, Luis; Perello Muntan, Jordi; Ruiz Ramírez, Marc; Spadaro, Salvatore; Junyent Giralt, Gabriel; Comellas Colome, Jaume
    Journal of optical communications and networking
    Date of publication: 2009-07
    Journal article

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    Aiming at better resource utilization, an important requirement of future optical transport networks is the capability to accommodate subwavelength client flows efficiently. This can be put into action thanks to the enhanced traffic engineering (TE) protocols provided within the generalized multiprotocol label switching (GMPLS) standardization. The present paper concentrates on the design and implementation of a GMPLS-controlled grooming-capable transport infrastructure, namely, the automatically switched optical network (ASON)ÕGMPLS CARISMA test bed. Through the paper, the operation of a GMPLS-controlled multilayer network architecture is introduced, subsequently highlighting implementation issues that come to light. Special attention is devoted to a centralized flow reallocation module deployed in the CARISMA test bed to minimize the overall network cost. In this context, an integer linear programming (ILP) formulation to obtain its optimal cost is derived and low-weighted metaheuristics providing a nearly optimal solution are additionally proposed. All contributions in the paper are supported by illustrative experimental results.