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  • Experimental assessment of bulk path restoration in multi-layer networks using PCE-based global concurrent optimization

     Castro Casales, Alberto; Martínez, Ricardo; Casellas, Ramón; Velasco Esteban, Luis; Muñoz González, Raul; Vilalta, Ricard; Comellas Colome, Jaume
    Journal of lightwave technology
    Date of publication: 2014-01-01
    Journal article

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    GMPLS-based multi-layer networks (MLN) combining packet and optical switching lead to jointly leverage intrinsic per-layer benefits such as statistical multiplexing and huge transport capacity. By doing so, efficient network resource utilization is attained through MLN TE strategies, i.e. grooming. In this context, an optical link failure may cause the disruption of multiple groomed packet LSPs. Thereby, efficient recovery schemes such as restoration are required. In dynamic restoration, the centralized Path Computation Element (PCE) sequentially computes backup paths for the set of failed packet LSPs using the TE database (TED). Since the TED is not updated until an LSP is actually set up, it is very likely that the PCE assigns the same network resources to different backup paths. This does increase resource contention and not fully exploits the potential grooming opportunities among the backup LSPs; consequently, the restorability metric performs poorly. To improve this, a designed PCE Global Concurrent Optimization (GCO) architecture is implemented favoring grooming and lowering resource contention. The addressed problem, referred to as Bulk pAth REstoration in Multi-layer Optical networks (BAREMO), is formally modeled and stated using a MILP formulation. Then, a heuristic algorithm solving the BAREMO problem is devised. The experimental performance evaluation is conducted within the ADRENALINE testbed. Besides validating the PCE GCO architecture, its performance is compared with a sequential PCE for several traffic loads and failure rates. The results show that the PCE GCO improves remarkably restorability compared to the sequential PCE at the expenses, however, of increasing the restoration time.

  • Dynamic restoration in multi-layer IP/MPLS-over-flexgrid networks

     Castro Casales, Alberto; Velasco Esteban, Luis; Comellas Colome, Jaume; Junyent Giralt, Gabriel
    Design of Reliable Communication Networks (DRCN)
    Presentation's date: 2013-03
    Presentation of work at congresses

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    The recent advances in photonic technology will allow deploying flexgrid-based optical core networks in the near future. Although that technology favors more efficient spectrum utilization, multilayer IP/MPLS-over-flexgrid networks would still be needed to groom together client flows, coming from access and metro networks, into optical connections. In this scenario, multi-flow transponders (MF-TPs) will provide additional flexibility allowing reconfiguration of optical connections to be performed. To be operated, a distributed control plane together with a centralized Path Computation Element (PCE) could be used. In the event of a failure, tens or hundreds of client flows could become disconnected and thus, restoration routes need to be found by the PCE for these flows. In standard restoration, path computation for each client flow is performed which derives into resource contention as a result of several connections trying to use some common resources, and poor resource utilization as a result of the reduction of grooming levels. In this paper, we deal with these problems and solve the DYNamic restorAtion in Multi-layer IP/MPLS-over-flexgrid Optical networks (DYNAMO) problem. Client flows' restoration requests are grouped into a single bulk in the PCE. Afterwards, a Global Concurrent Optimization (GCO) module solves the DYNAMO problem finding routes for all the flows in the bulk. The DYNAMO problem is modeled by using mathematical programming. However, as a consequence of its complexity and the stringent times within which the problem has to be solved, a GRASP-based heuristic is used. Exhaustive simulation results performed on two national core topologies show that a PCE with a GCO module solving DYNAMO highly improves restorability and reduces remarkably the number and capacity of MF-TPs, at the expense of some increment in restoration times.

  • 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.

  • 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.

  • An elastic networks OMNeT++-based simulator

     Asensio Garcia, Adrian; Castro Casales, Alberto; 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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    An increasing number of studies about flexgrid-based elastic optical networks are currently being carried out by industry as well as academic research teams. As access to real test-beds is limited, there is a lack of effective tools that emulate realistic scenarios for testing algorithms and network architectures. In this paper, we present a simulation framework based on an active stateful Path Computation Element (PCE) with Global Concurrent Optimization (GCO) for flexgrid optical networks. The simulator is fully configurable and allows implementing and testing new algorithms and architectures easily and quickly.

  • Global concurrent optimization: advantages and opportunities in flexgrid-based networks

     Castro Casales, Alberto; Velasco Esteban, Luis; Comellas Colome, Jaume; Junyent Giralt, Gabriel
    International Conference on Transparent Optical Networks
    Presentation's date: 2013-06
    Presentation of work at congresses

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    In future flexgrid core networks the amount of lightpaths might increase significantly as a consequence of the finer granularity in the use of the optical spectrum. Different spectrum bandwidth can be allocated to each lightpath as a function of, among others, the bitrate amount to be conveyed and the modulation format used. As result, spectrum fragmentation might appear leading to non-optimal resource utilization. In addition, a failure in a fibre link could trigger hundreds, or even thousands, of path computations requests to a centralized Path Computation Element (PCE). Latter examples can benefit from using the recently standardized Global Concurrent Optimization (GCO), which enhances PCE's computation capabilities. In this paper we present two opportunities to take advantage of the PCE+GCO architecture: spectrum defragmentation and restoration.

  • Experimental validation of dynamic restoration in GMPLS-controlled multi-layer networks using PCE-based global concurrent optimization

     Martínez, Ricardo; Castro Casales, Alberto; Casellas, Ramón; Muñoz González, Raul; Velasco Esteban, Luis; Vilalta, Ricardo; Comellas Colome, Jaume
    Optical Fiber Communication Conference and Exposition and National Fiber Optic Engineers Conference
    Presentation's date: 2013
    Presentation of work at congresses

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    An experimental validation of a PCE-based GCO architecture for dynamic restoration in GMPLS multi-layer networks is presented. This solution better addresses the concurrence of multiple connection requests favoring grooming objectives and attaining higher restorability.

  • 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.

  • 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.

  • Characterization and design of coherent optical OFDM transmission systems based on Hartley Transform

     Chochol, Marcin
    Defense's date: 2013-11-25
    Department of Signal Theory and Communications, Universitat Politècnica de Catalunya
    Theses

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  • 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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  • 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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  • 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.

  • Experimental evaluation of a dynamic PCE-based regenerator-efficient IA-RWA algorithm in translucent WSON

     Castro Casales, Alberto; Martínez, Ricardo; Velasco Esteban, Luis; Casellas, Ramón; Muñoz González, Raul; Comellas Colome, Jaume
    European Conference and Exhibition on Optical Communication
    Presentation's date: 2012-09
    Presentation of work at congresses

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    Abstract (40-Word Limit): We devise a novel dynamic PCE-based impairment-aware RWA algorithm in translucent GMPLS WSON that minimizes regenerator usage. Experimental evaluation carried out on the Open GMPLS/PCE control plane of CTTC ADRENALINE test-bed shows that significant improvements (>340%) are attained in terms of the offered traffic load.

  • 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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  • Value optimization of survivable multilayer IP/MPLS-over-WSON networks

     Velasco Esteban, Luis; González de Dios, Óscar; Ricciardi, Sergio; Castro Casales, Alberto; Muñoz, Fernando; Careglio, Davide; Comellas Colome, Jaume
    Photonic network communications
    Date of publication: 2012-05-01
    Journal article

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  • Cross-layer optimization in Optical Networks  Open access

     Angelou, Marianna
    Defense's date: 2012-04-16
    Department of Computer Architecture, Universitat Politècnica de Catalunya
    Theses

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    Network planning and operation in core optical networks require processes that lead to a cost-effective network able to effectively accommodate the given traffic demands. Crosslayer techniques that exploit information coming from the transport plane to serve either the network planning or the operation phases have been proposed to achieve optimal resource utilization and network performance. Dynamic impairment-aware networking refers to a solution that utilizes the dynamicity as well as the valuable physical-layer information of a reconfigurable WDM network to provide a smooth transition from the quasi-static networking of today to an intelligent reconfigurable and physical impairment-aware architecture. The concept of physical layer awareness allows intelligent techniques to offer optimal planning, dynamic configuration and management of the network while ensuring strong quality of transmission (QoT). A physical-layer performance estimating tool called Q-tool, has been designed and developed to deliver fast and accurate QoT assessments in dynamic single line-rate WDM networks employing 10 Gb/s OOK systems. The Q-tool was developed so as to feed with QoT evaluations the various cross-layer modules including offline RWA, monitor placement, regenerator placement, online RWA and failure handling. The significance of the physical-layer awareness and the role of Q-tool in the online routing strategy have been experimentally investigated using an impairment-enabled control-plane testbed. A cross-layer module that utilizes physical layer information to optimize the planning phase of single line-rate networks has been also developed; a monitor placement scheme was designed that takes into account partial monitoring information coming from the physical layer to decide the optimum number and locations of the optical monitoring devices. A techno-economic analysis was also conducted to explore the cost implications stemming from the resource optimization of a dynamic single line-rate network. Impairment aware and impairment-unaware algorithms along with the developed QoT tool were used to compare the planning solutions in terms of CapEx and OpEx. The challenges arising in the core networks of the next generation have also been addressed. Flexible optical networking has been introduced by the research community as a way to offer efficient utilization of the available optical resources while offering ultra-high speed rates. As opposed to the rate-specific and fixed-grid solution of a mixed line-rate (MLR) network, flexible networks are bandwidth agnostic and have the ability to adapt on- demand the delivered bit-rate. Yet, the increased level of flexibility imposes complex requirements; during network operation traffic is changing with time, leaving windows of spectrum of variable size unused. Moreover, interference from the neighbouring channels has to be taken into account and sufficient guard-bands ought to be considered. In such context the physical layer requirements for a spectrum-flexible optical superchannel were experimentally investigated by implementing a set of networking scenarios. The importance of the result is that it can act as input for cognitive algorithms that will enable a novel networking paradigm. Finally next generation core networks were evaluated from a cost, spectral and energy perspective so as to give a comprehensive view of the potential of the proposed technologies. The resource optimization achieved by flexible networks has been compared to single and mixed line-rate networks under the prism of cost and energy efficiency. It was shown that the capability of flexible networks to allocate efficiently the available spectrum, counterbalances the additional capital expenditures that are required to migrate to a multi-carrier system. In addition flexible networks achieve low energy per bit as they use just the amount of network resources needed for the given input traffic.

  • 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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  • 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.

  • Scalable hybrid path computation procedure for PCE-based

     Hernandez Sola, Guillem; Perello Muntan, Jordi; Agraz Bujan, Fernando; Spadaro, Salvatore; Comellas Colome, Jaume; Junyent Giralt, Gabriel
    International Conference on Transparent Optical Networks
    Presentation's date: 2011-06-27
    Presentation of work at congresses

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  • 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.

  • Scalable hybrid path computation procedure for PCE-based multi-domain WSON networks

     Hernandez Sola, Guillem; Perello Muntan, Jordi; Agraz Bujan, Fernando; Spadaro, Salvatore; Comellas Colome, Jaume; Junyent Giralt, Gabriel
    International Conference on Transparent Optical Networks
    Presentation's date: 2011
    Presentation of work at congresses

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    In the Hierarchical Path Computation Element (H-PCE) architecture, an optimum end-to-end path is computed using a hierarchical relationship among PCEs. An H-PCE-based path computation procedure provides low network blocking probability meanwhile it results on a great amount of control overhead messages. In this paper we propose a hybrid path computation procedure based on the H-PCE architecture and the Backward Recursive PCE-Based Computation (BRPC). Extensive simulation results show that the proposed approach performs better than H-PCE in terms of network control overhead.

  • 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.

  • Solutions for building service oriented optical networks

     Escalona Zorita, Eduard
    Defense's date: 2011-05-04
    Department of Signal Theory and Communications, Universitat Politècnica de Catalunya
    Theses

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  • Characterization and desing of multifunction photonic devices for next-generation fiber-to-the-home optical network units  Open access

     Schrenk, Bernhard
    Defense's date: 2011-04-28
    Department of Signal Theory and Communications, Universitat Politècnica de Catalunya
    Theses

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    El estudio e investigación en el campo de las redes ópticas de acceso han sido fomentadas en años recientes debido a la continua migración de Servicios multimedia que son ofrecidos a través de Internet. Aunque los dispositivos utilizados para implementar Fiber-to-the-Home (fibra a casa), que reemplazan las soluciones tradicionales basadas en cable de cobre, están basadas aún en micro-óptica, se puede prever una evolución hacia integración fotónica. Todavía queda la pregunta acerca de los diseños necesarios para este paso importante de integración, que debe ser optimizado en términos del desempeño de transmisión, eficiencia energética y costo con el fin de lograr todos los requerimientos de las redes fotónicas de siguiente generación. Como elemento más crítico en las redes de acceso ópticas es el equipo en los clientes, este trabajo se centra en éste. Los temes cubiertos abarcan una gama amplia e incluyen: el reciclado de longitudes de onda para transmisión de datos en full-dúplex a través de una sola frecuencia óptica; la generación de formatos de modulación avanzados con moduladores semiconductores de bajo costo y factor pequeño de integración; soporte de amplificación óptica a través de técnicas de sembrado y el soporte de funcionalidades de capes superiores en la capa física. Después de la prueba principal de las técnicas propuestas, se resaltan los beneficios, impedimentos y caminos de reemplazo hacia sistemas fotónicos multifuncionales a través de casos de estudio. Por su parte, los diseños más representativos se profundizan más sobre todo por su posibilidad de ser integrados fotónicamente.

    Optical access technology has experienced a boost in the last years, thanks to the continuously migrating multimedia services that are offered over the internet. Though the devices used for deploying Fiber-to-the-Home instead of traditional copper-based solutions are still based on micro-optics, an evolution towards photonic integration can be foreseen. What remains is the question about the exact designs for this important step of integration, which should be optimized in terms of transmission performance, energy efficiency and cost to address all requirements of next-generation photonic networks. As the most critical element in optical access, the customer premises equipment is in primary focus of this discussion. The covered topics span over a wide range and include wavelength recycling for full-duplex data transmission on a single optical frequency, the generation of advanced modulation formats with low-cost semiconductor modulators with small form factor, support for optical amplification by means of seeding techniques and the support of higher layer functionality at the physical layer. Next to the principal proof of the proposed techniques, the benefits, impediments and upgrade paths towards multifunctional photonic systems are highlighted in different case studies, while the most representative designs are further discussed in their capability of being photonically integrated.

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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.

  • Mixed integration of CDIO skills into telecommunication engineering curricula

     Sayrol Clols, Elisa; Bragos Bardia, Ramon; Alarcon Cot, Eduardo Jose; Cabrera Bean, Margarita Asuncion; Calveras Auge, Ana M.; Comellas Colome, Jaume; O'callaghan Castella, Juan Manuel; Pegueroles Valles, Josep Rafel; Pla, E; Prat Viñas, Luis; Saez Moreno, German; Sardà ., J; Tallon Montoro, Carme
    Elektronika ir elektrotechnika
    Date of publication: 2010
    Journal article

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  • Proceso de inversión de competencias genéricas en los nuevos planes de estudios de grado de la ETSETB de acuerdo con el modelo CDIO

     Bragos Bardia, Ramon; Alarcon Cot, Eduardo Jose; Cabrera Bean, Margarita Asuncion; Calveras Auge, Ana M.; Comellas Colome, Jaume; O'callaghan Castella, Juan Manuel; Pegueroles Valles, Josep Rafel; Prat Viñas, Luis; Saez Moreno, German; Sardà ., J; Sayrol Clols, Elisa
    Congreso de Tecnologías Aplicadas a la Enseñanza de la Electrónica
    Presentation's date: 2010-04-13
    Presentation of work at congresses

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    Performance evaluation of a hybrid OBS/OCS network with QoS differentiation based on packet loss/delay requirements  Open access

     Perello Muntan, Jordi; Guinea, Nuria de; Spadaro, Salvatore; Junyent Giralt, Gabriel; Comellas Colome, Jaume
    International Conference on Transparent Optical Networks
    Presentation's date: 2010-06-28
    Presentation of work at congresses

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    This paper introduces and evaluates a hybrid OBS/OCS switch for Quality of Service (QoS) differentiation in next-generation all-optical transport networks. Depending on their QoS requirements, incoming IP packets are collected in delay-sensitive or loss-sensitive assembly queues. Once assembled, those departing delay or losssensitive bursts are sent to the destination over a parallel all-optical hybrid network, where a set of switch ports and wavelengths are dedicated to delay-sensitive OBS-like transmission based on Just Enough Time (JET), whereas the remainder are dedicated to loss-sensitive OCS-like transmission. The obtained results validate the differentiated transport services in the deployed reference network scenario. Moreover, they show that circuit set-up retries are mandatory in OCS to carry loss-sensitive traffic efficiently.

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    Analysis of traffic engineering information dissemination strategies in PCE-based multi-domain optical networks  Open access

     Spadaro, Salvatore; Perello Muntan, Jordi; Hernandez Sola, Guillem; Moreno, A.; Agraz Bujan, Fernando; Comellas Colome, Jaume; Junyent Giralt, Gabriel
    International Conference on Transparent Optical Networks
    Presentation's date: 2010-06-28
    Presentation of work at congresses

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    This paper presents and compares different TE information dissemination strategies between Path Computation Elements (PCEs) in multi-domain optical networks. In such network context, recent studies have found that path computation only with local domain visibility yields poor network performance. Accordingly, certain visibility between domains seems necessary. Aiming to fit the confidentiality requirements of the composing domains while improving the final network blocking probability, novel link aggregation techniques have been proposed, which summarize the state of network domains resources efficiently. This aggregated link information is afterwards disseminated to all the remainder domains in the network. To this end, we introduce different update triggering policies to make a good trade-off between routing information scalability and inaccuracy. The performance of all contributions has been supported by illustrative simulation results.

  • Scalable path computation flooding approach for PCE-based multi-domain networks

     Perello Muntan, Jordi; Hernandez Sola, Guillem; Agraz Bujan, Fernando; Spadaro, Salvatore; Comellas Colome, Jaume
    ETRI journal
    Date of publication: 2010-08
    Journal article

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  • Using updated neighbor state information for efficient contention avoidance in OBS networks

     Perello Muntan, Jordi; Agraz Bujan, Fernando; Spadaro, Salvatore; Comellas Colome, Jaume; Junyent Giralt, Gabriel
    Computer communications
    Date of publication: 2010-01
    Journal article

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  • 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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  • Homodyne OLT-ONU design for access optical networks

     Fabrega Sanchez, Josep Maria
    Defense's date: 2010-05-17
    Department of Signal Theory and Communications, Universitat Politècnica de Catalunya
    Theses

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  • Scalable, Tunable and Resilient Optical Networks Guaranteeing Extremely-high Speed Transport

     Spadaro, Salvatore; Sole Pareta, Josep; Perello Muntan, Jordi; Careglio, Davide; Velasco Esteban, Luis; Junyent Giralt, Gabriel; Comellas Colome, Jaume
    Participation in a competitive project

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  • projecte GEYSERS

     Junyent Giralt, Gabriel; Spadaro, Salvatore; Comellas Colome, Jaume; Perello Muntan, Jordi
    Participation in a competitive project

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  • Experimental UpdateLess Evolutive Routing

     Junyent Giralt, Gabriel; Comellas Colome, Jaume; Cabellos Aparicio, Alberto; Careglio, Davide; Perello Muntan, Jordi; Sole Pareta, Josep; Spadaro, Salvatore
    Participation in a competitive project

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  • A Dynamic Impairment-Awate Networking Solution for Transparent Mesh Optical Networks

     Comellas Colome, Jaume; Sole Pareta, Josep
    IEEE communications magazine
    Date of publication: 2009-05
    Journal article

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    Burst contention avoidance schemes in hybrid GMPLS-enabled OBS/OCS optical networks  Open access

     Perello Muntan, Jordi; Spadaro, Salvatore; Comellas Colome, Jaume; Junyent Giralt, Gabriel
    International Conference on Optical Networking Design and Modeling
    Presentation's date: 2009-02-18
    Presentation of work at congresses

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    Hybrid optical network architectures, combining benefits of optical circuit and burst switching technologies, become a natural evolution to improve overall network performance while reducing related costs. This paper concentrates on preventive contention avoidance schemes to decrease burst loss probability at the OBS layer of such hybrid network scenarios. Into operation, the proposed solution locally reacts to highly loaded downstream node situations by preventively deflecting bursts through a less loaded neighbor. Two different approaches for disseminating adjacent nodes state information are presented and extensively evaluated. In the first approach, current node state information is propagated downstream in the burst control packet, keeping pace with OBS traffic dynamics. The second approach targets at lower control overhead. In this case, averaged node state statistics are included in the Hello messages of the GMPLS Link Management Protocol (LMP) protocol, which are exchanged between neighboring nodes over the OCS control layer every 150 ms. The obtained results validate the applicability of both approaches. Moreover, they indicate that, depending on the mean burst size, either one or the other approach is favorable.

  • 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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    Some open issues in multi-domain/multi-operator/multi-granular ASON/GMPLS networks  Open access

     Spadaro, Salvatore; Velasco Esteban, Luis; Perello Muntan, Jordi; Agraz Bujan, Fernando; Comellas Colome, Jaume; Junyent Giralt, Gabriel
    International Conference on Transparent Optical Networks
    Presentation's date: 2009-06-29
    Presentation of work at congresses

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    Large optical backbone networks may be composed of several domains, each one controlled by different administrators/operators. Besides, the bandwidth granularity of these domains may be different. Label Switched Paths (LSPs) provisioning in multi-domain/multi-operators/multi-layer network scenarios is a challenging problem actually, which has to be properly faced. In this paper, some open issues related to end-to-end bandwidth provisioning are discussed. Among others, the grooming problem in multi-layer/multi-domain optical networks and the performance degradation of recovery mechanisms due to limited inter-domain knowledge are analyzed.

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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.

  • RESOURCE MANAGEMENT IN gmPLS-CONTROLLED HYBRID OBS/OCS TRANSPORT NETWORKS.

     Perello Muntan, Jordi
    Defense's date: 2009-06-19
    Department of Signal Theory and Communications, Universitat Politècnica de Catalunya
    Theses

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  • RECOVERY MECHANISMS IN ASON/GMPLS NETWORKS.

     Velasco Esteban, Luis
    Defense's date: 2009-05-29
    Department of Signal Theory and Communications, Universitat Politècnica de Catalunya
    Theses

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  • Wavelength Selective Switches time requirements for shared path protection in ASON/GMPLS rings

     Velasco Esteban, Luis; Spadaro, Salvatore; Comellas Colome, Jaume; Junyent Giralt, Gabriel
    European Conference on Optical Communication
    Presentation of work at congresses

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