On IP over WDM burst-switched long haul and metropolitan area networks

The IP over Wavelength Division Multiplexing (WDM) network is a natural evolution ushered in by the phenomenal advances in networking technologies and technical breakthroughs in optical communications, fueled by the increasing demand in the reduction of operation costs and the network management complexity. The unprecedented bandwidth provisioning capability and the multi-service supportability of the WDM technology, in synergy with the data-oriented internetworking mechanisms, facilitates a common shared infrastructure for the Next Generation Internet (NGJ). While NGI targets to perform packet processing directly on the optical transport layer, a smooth evolution is critical to success. Intense research has been conducted to design the new generation optical networks that retain the advantages of packet-oriented transport prototypes while rendering elastic network resource utilization and graded levels of service. This dissertation is focused on the control architecture, enabling technologies, and performance analysis of the WDM burst-switched long haul and Metropolitan Area Networks (MANs). Theoretical analysis and simulation results are reported to demonstrate the system performance and efficiency of proposed algorithms. A novel transmission mechanism, namely, the Forward Resource Reservation (ERR) mechanism, is proposed to reduce the end-to-end delay for an Optical Burst Switching (OBS)-based IP over WDM system. The ERR scheme adopts a Linear Predictive Filter and an aggressive reservation strategy for data burst length prediction and resource reservation, respectively, and is extended to facilitate Quality of Service (QoS) differentiation at network edges. The ERR scheme improves the real-time communication services for applications with time constraints without deleterious system costs. The aggressive strategy for channel holding time reservations is proposed. Specifically, two algorithms, the success probability-driven (SPD) and the bandwidth usage-driven (BUD) ones, are proposed for resource reservations in the FRRenabled scheme. These algorithms render explicit control on the latency reduction improvement and bandwidth usage efficiency, respectively, both of which are important figures of performance metrics. The optimization issue for the FRR-enabled system is studied based on two disciplines - addressing the static and dynamic models targeting different desired objectives (in terms of algorithm efficiency and system performance), and developing a \u27\u27crank back\u27\u27 based signaling mechanism to provide bandwidth usage efficiency. The proposed mechanisms enable the network nodes to make intelligent usage of the bandwidth resources. In addition, a new control architecture with enhanced address resolution protocol (E-ARP), burst-based transmission, and hop-based wavelength allocation is proposed for Ethernet-supported IP over WDM MANs. It is verified, via theoretical analysis and simulation results, that the E-ARP significantly reduces the call setup latency and the transmission requirements associated with the address probing procedures; the burst-based transport mechanism improves the network throughput and resource utilization; and the hop-based wavelength allocation algorithm provides bandwidth multiplexing with fairness and high scalability. The enhancement of the Ethernet services, in tandem with the innovative mechanisms in the WDM domain, facilitates a flexible and efficient integration, thus making the new generation optical MAN optimized for the scalable, survivable, and IP-dominated network at gigabit speed possible

An assembly and offset assignment scheme for self-similar traffic in optical burst switching

Includes bibliographical references.Optical Burst Switching (OBS) is a viable technology for the next generation core network. We propose an FEC-assembly scheme that efficiently assembles self-similar traffic and a Pareto-offset assignment rather than a constant offset assignment. Two buffers, a packet buffer and a burst buffer, are implemented at the Label Edge Router (LER), buffering traffic in the electronic domain. The assembler, between the packet and burst buffers, is served by the packet queue while the assembler serves the burst queue. We outline advantages of why burst assembly cannot be implemented independent of offset assignment. The two schemes must be implemented in a complementary way if QoS is to be realized in an OBS network. We show that there is a direct relation between OBS network performance with burst assembly and offset assignment. We present simulation results of the assembly and offset assignment proposals using the ns2 network simulator. Our results show that the combination of the proposed FEC-Based assembly scheme with the proposed Pareto-offset assignment scheme give better network performance in terms of burst drop, resource contention and delay. Key to any traffic shaping is the nature traffic being shaped. This work also compares performance of both traditional exponential traffic with realistic Self-Similar traffic of Internet traffic on the proposed assembly and offset assignment schemes. In our simulations, we assume that all Label Switch Routers (LSR) have wavelength converters and are without optical buffers. We use Latest Available Unused Channel with Void Filling (LAUC-VF) scheduling scheme and use Just Enough Time (JET) reservation scheme

Performance issues in optical burst/packet switching

The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-642-01524-3_8This chapter summarises the activities on optical packet switching (OPS) and optical burst switching (OBS) carried out by the COST 291 partners in the last 4 years. It consists of an introduction, five sections with contributions on five different specific topics, and a final section dedicated to the conclusions. Each section contains an introductive state-of-the-art description of the specific topic and at least one contribution on that topic. The conclusions give some points on the current situation of the OPS/OBS paradigms

Delay-throughput curves for timer-based OBS burstifiers with light load

The OBS burstifier delay-throughput curves are analyzed in this paper. The burstifier incorporates a timer-based scheme with minimum burst size, i. e., bursts are subject to padding in light-load scenarios. Precisely, due to this padding effect, the burstifier normalized throughput may not be equal to unity. Conversely, in a high-load scenario, padding will seldom occur. For the interesting light-load scenario, the throughput delay curves are derived and the obtained results are assessed against those obtained by trace-driven simulation. The influence of long-range dependence and instantaneous variability is analyzed to conclude that there is a threshold timeout value that makes the throughput curves flatten out to unity. This result motivates the introduction of adaptive burstification algorithms, that provide a timeout value that minimizes delay, yet keeping the throughput very close to unity. The dependence of such optimum timeout value with traffic long-range dependence and instantaneous burstiness is discussed. Finally, three different adaptive timeout algorithms are proposed, that tradeoff complexity versus accuracy.This work was funded by Spanish Ministry of Education and Science (projects CAPITAL TEC2004-05622-C04-04 and PINTA TEC2004-06437-C05-03

Effect of number of burst assemblers on TCP performance in optical burst switching networks

Burst assembly mechanism is one of the fundamental factors that determine the performance of an optical burst switching (OBS) network. In this paper, we investigate the influence of number of burstifiers on TCP performance for an OBS network. An ns2-based OBS network simulator is developed for simulating the optical network. The goodput of TCP flows between an ingress and an egress nodes traveling through an optical network is studied for different values of the number of assembly buffers per destination. First, the losses resulting from the congestion in the core OBS network are modeled using a burst independent Bernoulli loss model. Then, a background burst traffic is generated to create contention at a core node in order to realize a burst dependent loss model. Simulation results show that for an OBS network employing timer-based assembly algorithm, TCP goodput increases as the number of burst assemblers is increased for both types of loss models. The improvement from one burstifier to moderate number of burst assemblers is significant (15-50% depending on the burst loss probability, processing delay and the TCP version), but the goodput difference between moderate number of buffers andperflow aggregation is relatively small, implying that a cost-effective OBS edge switch implementation should use moderate number of assembly buffers per destination for enhanced TCP performance. © 2006 IEEE

QoS Considerations in OBS Switched Backbone Net-Works

Optical Burst Switching (OBS) was proposed as a hybrid switching technology solution to handle the multi-Terabit volumes of traffic anticipated to traverse Future Generation backbone Networks. With OBS, incoming data packets are assembled into super-sized packets called data bursts and then assigned an end to end light path. Key challenging areas with regards to OBS Networks implementation are data bursts assembling and scheduling at the network ingress and core nodes respectively as they are key to minimizing subsequent losses due to contention among themselves in the core nodes. These losses are significant contributories to serious degradation in renderable QoS. The paper overviews existing methods of enhancing it at both burst and transport levels. A distributed resources control architecture is proposed together with a proposed wavelength assignment algorithm

Prévision du trafic Internet : modèles et applications

Avec l'essor de la métrologie de l'Internet, la prévision du trafic s'est imposée comme une de ses branches les plus importantes. C'est un outil puissant qui permet d'aider à la conception, la mise en place et la gestion des réseaux ainsi qu'à l'ingénierie du trafic et le contrôle des paramètres de qualité de service. L'objectif de cette thèse est d'étudier les techniques de prévision et d'évaluer la performance des modèles de prévision et de les appliquer pour la gestion des files d'attente et le contrôle du taux de perte dans les réseaux à commutation de rafales. Ainsi, on analyse les différents paramètres qui permettent d'améliorer la performance de la prévision en termes d'erreur. Les paramètres étudiés sont : la quantité de données nécessaires pour définir les paramètres du modèle, leur granularité, le nombre d'entrées du modèle ainsi que les caractéristiques du trafic telles que sa variance et la distribution de la taille des paquets. Nous proposons aussi une technique d'échantillonnage baptisée échantillonnage basé sur le maximum (Max-Based Sampling - MBS). Nous prouvons son efficacité pour améliorer la performance de la prévision et préserver l'auto-similarité et la dépendance à long terme du trafic. \ud Le travail porte aussi sur l'exploitation de la prévision du trafic pour la gestion du trafic et le contrôle du taux de perte dans les réseaux à commutation de rafales. Ainsi, nous proposons un nouveau mécanisme de gestion de files d'attente, baptisé α_SNFAQM, qui est basé sur la prévision du trafic. Ce mécanisme permet de stabiliser la taille de la file d'attente et par suite, contrôler les délais d'attente des paquets. Nous proposons aussi une nouvelle technique qui permet de garantir la qualité de service dans les réseaux à commutation de rafales en termes de taux de perte. Elle combine entre la modélisation, la prévision du trafic et les systèmes asservis avec feedback. Elle permet de contrôler efficacement le taux de perte des rafales pour chaque classe de service. Le modèle est ensuite amélioré afin d'éviter les feedbacks du réseau en utilisant la prévision du taux de perte au niveau TCP. \ud ______________________________________________________________________________ \ud MOTS-CLÉS DE L’AUTEUR : Modélisation et prévision du trafic, techniques d'échantillonnage, gestion des files d'attente, réseaux à commutation de rafales, contrôle du taux de perte, qualité de service, l'automatique

Migration strategies toward all optical metropolitan access rings

This paper was published in Journal of Lightwave Technology and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the IEEE website: http://dx.doi.org/10.1109/JLT.2007.901325. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.Nowadays, network operators are steadily deploying optical circuit switching (OCS) equipment in their metropolitan networks in order to cope with traffic increase and, most importantly, in order to reduce capital expenditures and operational expenditures of existing active technologies. On the other hand, optical burst switching (OBS) technology is expected to become mature in the medium term, and it may be used as an alternative to current OCS networks due to its potential advantages in terms of bandwidth allocation granularity. While OBS is being extensively studied in the literature, little attention has been paid in conducting a comparative analysis of OBS versus OCS, especially concerning cost analysis. In this paper, we provide a comparative analysis of OBS versus OCS as an evolutionary technology for all-optical rings in the metropolitan-access network. This paper is specifically targeted toward optimizing the number of optoelectronic receivers and wavelengths with real traffic matrices from the metropolitan rings in Madrid, Spain. Such matrices also include traffic projections of foreseeable broadband services, which are based on a market analysis from the largest operator in Spain. Our findings show that OCS might be more efficient than OBS in the metro-access segment, which is characterized by a highly centralized traffic pattern. However, the more distributed the traffic is, the more efficient the OBS is as well. Consequently, OBS might be better suited to metro-core networks, which show a more distributed and dynamic traffic pattern.The authors would like to thank the e-Photon/ONe+ network of excellenc

Flow control and service differentiation in optical burst switching networks

Cataloged from PDF version of article.Optical Burst Switching (OBS) is being considered as a candidate architecture for the next generation optical Internet. The central idea behind OBS is the assembly of client packets into longer bursts at the edge of an OBS domain and the promise of optical technologies to enable switch reconfiguration at the burst level therefore providing a near-term optical networking solution with finer switching granularity in the optical domain. In conventional OBS, bursts are injected to the network immediately after their assembly irrespective of the loading on the links, which in turn leads to uncontrolled burst losses and deteriorating performance for end users. Another key concern related to OBS is the difficulty of supporting QoS (Quality of Service) in the optical domain whereas support of differentiated services via per-class queueing is very common in current electronically switched networks. In this thesis, we propose a new control plane protocol, called Differentiated ABR (D-ABR), for flow control (i.e., burst shaping) and service differentiation in optical burst switching networks. Using D-ABR, we show with the aid of simulations that the optical network can be designed to work at any desired burst blocking probability by the flow control service of the proposed architecture. The proposed architecture requires certain modifications to the existing control plane mechanisms as well as incorporation of advanced scheduling mechanisms at the ingress nodes; however we do not make any specific assumptions on the data plane of the optical nodes. With this protocol, it is possible to almost perfectly isolate high priority and low priority traffic throughout the optical network as in the strict priority-based service differentiation in electronically switched networks. Moreover, the proposed architecture moves the congestion away from the OBS domain to the edges of the network where it is possible to employ advanced queueing and buffer management mechanisms. We also conjecture that such a controlled OBS architecture may reduce the number of costly Wavelength Converters (WC) and Fiber Delay Lines (FDL) that are used for contention resolution inside an OBS domain.Boyraz, HakanM.S

Dynamic threshold-based algorithms for communication networks

Ankara : The Department of Electrical and Electronics Engineering and the Institute of Engineering and Sciences of Bilkent University, 2009.Thesis (Master's) -- Bilkent University, 2009.Includes bibliographical references leaves 68-72.A need to use dynamic thresholds arises in various communication networking scenarios under varying traffic conditions. In this thesis, we propose novel dynamic threshold-based algorithms for two different networking problems, namely the problem of burst assembly in Optical Burst Switching (OBS) networks and of bandwidth reservation in connection-oriented networks. Regarding the first problem, we present dynamic threshold-based burst assembly algorithms that attempt to minimize the average burst assembly delay due to burstification process while taking the burst rate constraints into consideration. Using synthetic and real traffic traces, we show that the proposed algorithms perform significantly better than the conventional timer-based schemes. In the second problem, we propose a model-free adaptive hysteresis algorithm for dynamic bandwidth reservation in a connection-oriented network subject to update frequency constraints. The simulation results in various traffic scenarios show that the proposed technique considerably outperforms the existing schemes without requiring any prior traffic information.Toksöz, Mehmet AltanM.S