http://hdl.handle.net/2117/3130 2013-05-25T12:19:13Z http://hdl.handle.net/2117/17637 Title: A novel impairment aware RWA algorithm with consideration of QoT estimation inaccuracy Authors: Azodolmolky, Siamak; Pointurier, Yvan; Angelou, Marianna; Careglio, Davide; Solé Pareta, Josep; Tomkos, Ioannis Abstract: In all-optical networks the physical layer impairments accumulate along a lightpath and also vary dynamically, and a number of impairment aware routing and wavelength assignment (IA-RWA) techniques have been proposed in order to mitigate the physical layer impairments and find lightpaths that meet a required quality of transmission (QoT) constraint predefined by the network operator. However, in order to compute lightpaths, IA-RWAs typically rely on analytical models, which cannot be guaranteed to be fully accurate, and hence acceptance of lightpaths with poor QoT or rejection of lightpaths with acceptable QoT may ensue. We present a novel IA-RWA algorithm that not only considers the impact of physical impairments on RWA decisions, but also, for the first time, accounts for inaccuracy of the QoT estimators. The performance of our algorithm is compared with algorithms selected from the recent literature. All algorithms are evaluated through simulations in a realistic scenario. Our proposed novel algorithm outperforms the selected algorithms in terms of blocking rate and also the amount of required resources for achieving a very low (i.e., 5 £ 10¡6) blocking rate under similar assumptions. In addition we show that accounting for QoT estimation inaccuracy changes the performance of the proposed IA-RWA substantially, and hence that the QoT estimator inaccuracy is an important design parameter in transparent optical networking. 2013-02-11T15:03:22Z http://hdl.handle.net/2117/16105 Title: Service and resource differentiation in shared-path protection environments to maximize network operator's revenues Authors: Velasco Esteban, Luis Domingo; Ruiz Ramírez, Marc; Perelló Muntan, Jordi; Spadaro, Salvatore; Comellas Colomé, Jaume Abstract: 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. 2012-06-20T10:23:08Z http://hdl.handle.net/2117/15965 Title: A novel offline physical layer impairments aware RWA algorithm with dedicated path protection consideration Authors: Azodolmolky, Siamak; Klinkowski, Miroslaw; Pointurier, Yvan; Angelou, Marianna; Careglio, Davide; Solé Pareta, Josep; Tomkos, Ioannis Abstract: Physical layer impairments accumulate as light propagates through a lightpath in the transparent optical networks. Therefore, it is possible to provision a lightpath, while its quality of transmission (QoT) does not meet the required threshold. Considering the physical layer impairments in the network planning phase gives rise to a set of offline Impairments Aware Routing and Wavelength Assignment (IA-RWA) algorithms. There are very few offline IA-RWA algorithms that consider dedicated path protection demands. In this work we propose a novel offline IA-RWA algorithm, called Rahyab and perform a comparative performance evaluation study, which considers two enhanced algorithms from the literature. Simulation results indicates that demand pre-processing, diverse routing, and adaptive wavelength assignment are the main reasons of lower blocking rate of Rahyab algorithm compared to the selected algorithms. 2012-06-05T07:58:28Z http://hdl.handle.net/2117/15941 Title: Physical channel characterization for medium-range nanonetworks using flagellated bacteria Authors: Gregori, Maria; Llatser Martí, Ignacio; Cabellos Aparicio, Alberto; Alarcón Cot, Eduardo José Abstract: Nano-networks are the interconnection of nano-machines and as such expand the limited capabilities of a single nano-machine. Several techniques have been proposed so far to interconnect nano-machines. For short dis- tances (nm-mm ranges), researchers are proposing to use molecular motors and calcium signaling. For long distances (mm-m), pheromones are envisioned to transport information. In this work we propose a new mechanism for medium-range communications (nm- m): agellated bacteria. This technique is based on the transport of DNA-encoded information between emitters and receivers by means of a bacterium. We present a physical channel characterization and a simulator that, based on the previous characterization, simulates the transmission of a DNA-packet between two nano-machines. 2012-05-30T08:53:26Z http://hdl.handle.net/2117/14467 Title: N3Sim: A simulation framework for diffusion-based molecular communication Authors: Llatser Martí, Ignacio; Pascual, Iñaki; Garralda, N.; Cabellos Aparicio, Alberto; Alarcón Cot, Eduardo José Abstract: We designed N3Sim in order to simulate a set of nanomachines which communicate through molecular diffusion in a fluid medium. 2012-01-11T11:30:03Z http://hdl.handle.net/2117/14370 Title: GMPLS control plane network design with resilience guarantees Authors: Ruiz Ramírez, Marc; Perelló Muntan, Jordi; Velasco Esteban, Luis Domingo; Spadaro, Salvatore; Comellas Colomé, Jaume; Junyent Giralt, Gabriel Abstract: 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. 2011-12-30T09:30:58Z http://hdl.handle.net/2117/13515 Title: Offline routing and regenerator placement and dimensioning for translucent OBS networks Authors: Pedrola Escribà, Òscar; Careglio, Davide; Klinkowski, Miroslaw; Solé Pareta, Josep Abstract: The deployment of translucent optical networks is considered the most promising short term solution to decrease costs and energy consumption in optical backbone networks. In fact, translucent wavelength switched optical networks (WSONs) have recently received great attention from the research community due to their technological maturity. However, the inflexibility and coarse granularity of WSONs is(re)-fostering research interest in sub-wavelength switching technologies such as optical burst switching (OBS). In OBS, however, the majority of research works neglect the impact of physical layer impairments by considering either fully transparent (i.e., with optical 3R regeneration)or opaque (i.e., with electrical 3R regeneration) networks. For this very reason, in this paper we present a translucent OBS (T-OBS) network architecture which aims at bridging the gap between the transparent and opaque solutions. In the T-OBS network the problem of routing and regenerator placement and dimensioning (RRPD) emerges. Joint RRPD is a complex problem and, in order to approach it, we propose to decompose it into the routing and RPD subproblems. As a consequence, we provide a mixed integer linear programming formulation of the routing problem and several heuristic strategies for the RPD problem. Illustrative numerical results prove the effectiveness of these methods at minimizing the number of electrical 3R regenerators deployed in the network. Considering a broad range of network topologies, we show that the proposed RPD heuristics ensure a proper quality of transmission performance whilst at the same time providing a cost-effective T-OBS network architecture. 2011-10-17T08:33:26Z http://hdl.handle.net/2117/13389 Title: Large-scale measurement experiments of P2P-TV systems insights on fairness and locality Authors: Silverston, Thomas; Jakab, Lorand; Cabellos Aparicio, Alberto; Fourmaux, Olivier; Salamatian, Kavé; Kenjiro, Cho Abstract: P2P-TV is an emerging alternative to classical television broadcast systems. Leveraging possibilities offered by the Internet, several companies offer P2P-TV services to their customers. The overwhelming majority of these systems, however, is of closed nature, offering little insight on their traffic properties. For a better understanding of the P2P- TV landscape, we performed measurement experiments in France, Japan, Spain, and Romania, using different commercial applications. By using multiple measurement points in different locations of the world, our results can paint a global picture of the measured networks, inferring their main properties. More precisely, we focus on the level of collaboration between peers, their location and the effect of the traffic on the networks. Our results show that there is no fairness between peers and that is an important issue for the scalability of P2P-TV systems. Moreover, hundreds of Autonomous Systems are involved in the P2P-TV traffic and it points out the lack of locality-aware mechanisms for these systems. The geographic location of peers testifies the wide spread of these applications in Asia and highlights their worldwide usage. 2011-09-29T10:50:31Z http://hdl.handle.net/2117/13243 Title: Enhanced domain disjoint backward recursive TE path computation for PCE-based multi-domain networks Authors: Hernández Sola, Guillem; Perelló Muntan, Jordi; Agraz Bujan, Fernando; Velasco Esteban, Luis Domingo; Spadaro, Salvatore; Junyent Giralt, Gabriel Abstract: The ability of computing optimal routes poses new challenges when extending it to larger multi-domain network scenarios, as the quality of these computed endto-end inter-domain routes depends on the selection of the domain sequence to be traversed. In the scope of the Internet Engineering Task Force (IETF), the Path Computation Element (PCE) Working Group has not provided definitive solutions to address the domain sequence selection problem, being still a work in progress. To this goal, the Path Computation Flooding (PCF) approach appears as a possible extension to Backward Recursive PCE-based Computation (BRPC) to calculate optimal end-to-end inter-domain paths without requiring a pre-configured domain sequence. Nonetheless, PCF presents major scalability issues in terms of network control overhead and path computation complexity, thus pleading for more accurate domain sequence selection techniques. This paper describes two novel mechanisms to establish inter-domain paths calculating the sequence of domains to be crossed when it is not known in advance. Both procedures make a good trade-off between the control overhead introduced and the accuracy of the computed end-to-end route. The obtained simulation results show the benefits of the proposed contributions, drastically reducing the control overhead while keeping the connection blocking probability close to the optimal values. 2011-09-19T12:20:16Z http://hdl.handle.net/2117/13086 Title: Survivable IP/MPLS-Over-WSON multilayer network optimization Authors: Ruiz Ramírez, Marc; Pedrola Escribà, Òscar; Velasco Esteban, Luis Domingo; Careglio, Davide; Fernández Palacios, Juan Pedro; Junyent Giralt, Gabriel Abstract: 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. 2011-08-22T18:56:03Z http://hdl.handle.net/2117/12822 Title: On the benefits of optical gain-clamped amplification in optical burst switching networks Authors: Zannin, Marcelo; Ennser, Karin; Taccheo, Stefano; Careglio, Davide; Solé Pareta, Josep; Aracil Rico, Javier Abstract: This paper investigates the performance of an all-optical method for amplification gain control to be applied in the next generation of optical networks. An erbium-doped fiber amplifier is implemented in a simple and passive all-optical configuration known as optical gain-clamped optical amplifier (OA). The paper investigates the dynamic performance of the OA and discusses the interplay of amplifier dynamics with different traffic statistics. The investigation concerns exhaustive characterization of bit error rate performances under typical optical burst switching (OBS) traffic as well as special case of sudden power variation at the amplifier input. All obtained results show a reduction in the amplifier output power overshot compared to the case where the same OA operates without any gain stabilization technique. As an example, in the typical OBS traffic scenario, a reduction of 3 dB is observed. 2011-06-23T11:49:37Z http://hdl.handle.net/2117/10817 Title: Performance overview of the offset time emulated OBS network architecture Authors: Klinkowski, Miroslaw; Careglio, Davide; Solé Pareta, Josep; Marciniak, Marian Abstract: Optical burst switching (OBS) control architecture considers two different models for the management of the offset time in the network. The conventional OBS (C-OBS) introduces the offset time in soft-way by delaying the transmission of the burst relative to its control packet in the edge node. Another idea for an OBS architecture (E-OBS) comes from optical packet switching world and it intends to emulate offset time by means of an additional fiber delay unit introduced in the data path at the input port of the nodes. Although C-OBS has attracted lots of attention, in this paper we highlight that it possesses many difficulties that can be entirely removed in E-OBS. Issues such as unfairness in resource reservation, efficiency and complexity of burst scheduling, difficulty with alternative and backup routing, and quality of service (QoS) provisioning are studied. Moreover, E-OBS facilitates the application of several enhanced mechanisms. As an example, in this paper we analyze a QoS application based on a preemption window mechanism, which expands look-ahead processing window technique to the burst preemption context. Results show that this mechanism can achieve the performance of the conventional preemption scheme while avoiding the well-known problem of phantom burst generation. 2010-12-29T11:57:24Z http://hdl.handle.net/2117/10813 Title: Reactive and proactive routing in labelled optical burst switching networks Authors: Klinkowski, Miroslaw; Careglio, Davide; Solé Pareta, Josep Abstract: Optical burst switching architectures without buffering capabilities are sensitive to burst congestion. The existence of a few highly congested links may seriously aggravate the network throughput. Proper network routing may help in congestion reduction. The authors focus on adaptive routing strategies to be applied in labelled OBS networks, that is, with explicit routing paths. In particular, two isolated alternative routing algorithms that aim at network performance improvement because of reactive route selection are studied. Moreover, a nonlinear optimisation method for multi-path source-based routing, which aims at proactive congestion reduction is proposed. Comparative performance results are provided and some implementation issues are discussed. 2010-12-29T10:06:06Z http://hdl.handle.net/2117/10812 Title: Non-linear optimization for multi-path source routing in OBS networks Authors: Klinkowski, Miroslaw; Pioro, Michal; Careglio, Davide; Marciniak, Marian; Solé Pareta, Josep Abstract: Optical Burst Switching (OBS) architectures without buffering capabilities are sensitive to burst losses. A proper routing strategy may help to reduce such congestion. In this letter we present a novel approach for OBS multi-path source routing problem. Our solution is based on non-linear optimization with a straightforward calculation of partial derivatives. Simulation results demonstrate that optimized routing effectively reduces the overall burst loss probability with respect to shortest path and deflection routing. 2010-12-29T09:50:28Z http://hdl.handle.net/2117/10810 Title: Research in optical burst switching within the e-Photon/ONe network of excellence Authors: González de Dios, Óscar; Aracil Rico, Javier; Akar, Nail; Bjornstad, Steinar; Casoni, Maurizio; Christodoulopoulos, K.; Careglio, Davide; Fernández Palacios, Juan; Gauger, C.; Tosi Beleffi, Giorgio M.; Stol, Norvald; Simeonidou, Dimitra; Raffaelli, Carla; Overby, Harald; Nejabati, Reza; Morató, Daniel; Klinkowski, Miroslaw; Karasan, Ezhan; Hu, Guoqiang; Vlachos, K. Abstract: This paper presents a summary of Optical Burst Switching (OBS) research within the VI framework program e-Photon/ONe network of excellence. The paper includes network aspects such as routing techniques, resilience and contention resolution, together with burst switch architectures. On the other hand, we also discuss traffic analysis issues, Quality of Service (QoS) schemes, TCP/IP over OBS and physical layer aspects for OBS. 2010-12-29T09:29:45Z