Design and provisioning of WDM networks for traffic grooming

Wavelength Division Multiplexing (WDM) is the most viable technique for utilizing the enormous amounts of bandwidth inherently available in optical fibers. However, the bandwidth offered by a single wavelength in WDM networks is on the order of tens of Gigabits per second, while most of the applications\u27 bandwidth requirements are still subwavelength. Therefore, cost-effective design and provisioning of WDM networks require that traffic from different sessions share bandwidth of a single wavelength by employing electronic multiplexing at higher layers. This is known as traffic grooming. Optical networks supporting traffic grooming are usually designed in a way such that the cost of the higher layer equipment used to support a given traffic matrix is reduced. In this thesis, we propose a number of optimal and heuristic solutions for the design and provisioning of optical networks for traffic grooming with an objective of network cost reduction. In doing so, we address several practical issues. Specifically, we address the design and provisioning of WDM networks on unidirectional and bidirectional rings for arbitrary unicast traffic grooming, and on mesh topologies for arbitrary multipoint traffic grooming. In multipoint traffic grooming, we address both multicast and many-to-one traffic grooming problems. We provide a unified frame work for optimal and approximate network dimensioning and channel provisioning for the generic multicast traffic grooming problem, as well as some variants of the problem. For many-to-one traffic grooming we propose optimal as well as heuristic solutions. Optimal formulations which are inherently non-linear are mapped to an optimal linear formulation. In the heuristic solutions, we employ different problem specific search strategies to explore the solution space. We provide a number of experimental results to show the efficacy of our proposed techniques for the traffic grooming problem in WDM networks

Multicast protection and energy efficient traffic grooming in optical wavelength routing networks.

Zhang, Shuqiang.Thesis (M.Phil.)--Chinese University of Hong Kong, 2010.Includes bibliographical references (p. 74-80).Abstracts in English and Chinese.Abstract --- p.i摘要 --- p.ivAcknowledgements --- p.vTable of Contents --- p.viChapter Chapter 1 --- Background --- p.1Chapter 1.1 --- Routing and Wavelength Assignment --- p.1Chapter 1.2 --- Survivability in Optical Networks --- p.3Chapter 1.3 --- Optical Multicasting --- p.4Chapter 1.3.1 --- Routing and Wavelength Assignment of Optical Multicast --- p.5Chapter 1.3.2 --- Current Research Topics about Optical Multicast --- p.8Chapter 1.4 --- Traffic Grooming --- p.10Chapter 1.4.1 --- Static Traffic Grooming --- p.11Chapter 1.4.2 --- Dynamic Traffic Grooming --- p.13Chapter 1.5 --- Contributions --- p.15Chapter 1.5.1 --- Multicast Protection with Scheduled Traffic Model --- p.15Chapter 1.5.2 --- Energy Efficient Time-Aware Traffic Grooming --- p.16Chapter 1.6 --- Organization of Thesis --- p.18Chapter Chapter 2 --- Multicast Protection in WDM Optical Network with Scheduled Traffic --- p.19Chapter 2.1 --- Introduction --- p.19Chapter 2.2 --- Multicast Protection under FSTM --- p.22Chapter 2.3 --- Illustrative Examples --- p.28Chapter 2.4 --- Two-Step Optimization under SSTM --- p.37Chapter 2.5 --- Summary --- p.40Chapter Chapter 3 --- Energy Efficient Time-Aware Traffic Grooming in Wavelength Routing Networks --- p.41Chapter 3.1 --- Introduction --- p.41Chapter 3.2 --- Energy consumption model --- p.43Chapter 3.3 --- Static Traffic Grooming with Time awareness --- p.44Chapter 3.3.1 --- Scheduled Traffic Model for Traffic Grooming --- p.44Chapter 3.3.2 --- ILP Formulation --- p.44Chapter 3.3.3 --- Illustrative Numerical Example --- p.48Chapter 3.4 --- Dynamic Traffic Grooming with Time Awareness --- p.49Chapter 3.4.1 --- Time-Aware Traffic Grooming (TATG) --- p.51Chapter 3.5 --- Simulation Results of Dynamic Traffic Grooming --- p.54Chapter 3.5.1 --- 24-node USNET: --- p.55Chapter 3.5.2 --- 15-node Pacific Bell Network: --- p.59Chapter 3.5.3 --- 14-node NSFNET: --- p.63Chapter 3.5.4 --- Alternative Configuration of Simulation Parameters: --- p.67Chapter 3.6 --- Summary --- p.71Chapter Chapter 4 --- Conclusions and Future Work --- p.72Chapter 4.1 --- Conclusions --- p.72Chapter 4.2 --- Future Work --- p.73Bibliography --- p.74Publications during M.Phil Study --- p.8

Multicast Routing In Optical Access Networks

Widely available broadband services in the Internet require high capacity access networks. Only optical networking is able to efficiently provide the huge bandwidth required by multimedia applications. Distributed applications such as Video-Conferencing, HDTV, VOD and Distance Learning are increasingly common and produce a large amount of data traffic, typically between several terminals. Multicast is a bandwidth-efficient technique for one-to-many or many-to-many communications, and will be indispensable for serving multimedia applications in future optical access networks. These applications require robust and reliable connections as well as the satisfaction of QoS criteria. In this chapter, several access network architectures and related multicast routing methods are analyzed. Overall network performance and dependability are the focus of our analysis

Software Defined Applications in Cellular and Optical Networks

abstract: Small wireless cells have the potential to overcome bottlenecks in wireless access through the sharing of spectrum resources. A novel access backhaul network architecture based on a Smart Gateway (Sm-GW) between the small cell base stations, e.g., LTE eNBs, and the conventional backhaul gateways, e.g., LTE Servicing/Packet Gateways (S/P-GWs) has been introduced to address the bottleneck. The Sm-GW flexibly schedules uplink transmissions for the eNBs. Based on software defined networking (SDN) a management mechanism that allows multiple operator to flexibly inter-operate via multiple Sm-GWs with a multitude of small cells has been proposed. This dissertation also comprehensively survey the studies that examine the SDN paradigm in optical networks. Along with the PHY functional split improvements, the performance of Distributed Converged Cable Access Platform (DCCAP) in the cable architectures especially for the Remote-PHY and Remote-MACPHY nodes has been evaluated. In the PHY functional split, in addition to the re-use of infrastructure with a common FFT module for multiple technologies, a novel cross functional split interaction to cache the repetitive QAM symbols across time at the remote node to reduce the transmission rate requirement of the fronthaul link has been proposed.Dissertation/ThesisDoctoral Dissertation Electrical Engineering 201

On the Issues and Challenges of Fiber-Wireless (Fi-Wi) Networks

The objective of this article is to present various aspects of Fiber-Wireless (Fi-Wi) networks, which is a technology of current interest of the researchers. Fiber-wireless technology, known in short as “Fi-Wi,” is a combination of optical-fiber-based network and wireless network. Fi-Wi has recently come forward as one of the emerging future network technologies yet the term is often mixed up with wireless-fidelity (Wi-Fi) technology. In fact, Wi-Fi network could be included in a Fi-Wi architecture. Due to the unfamiliarity with the term, “Fi-Wi” and similar sounding commonly known “Wi-Fi,” many students, even academics and practitioners sometimes may not be able to differentiate between these. In the recent years, a good number of works on various issues of Fi-Wi have come out, but an overall survey with the latest advancements in the area is yet to be found. Hence, in this work, we analyze various issues and challenges of implementing Fi-Wi networks in practical scenarios to allow researchers to find future directions of research and general readers to understand the issues better

Esquema de controlo para redes multicast baseadas com classes

Doutoramento em Engenharia ElectrotécnicaThe expectations of citizens from the Information Technologies (ITs) are increasing as the ITs have become integral part of our society, serving all kinds of activities whether professional, leisure, safety-critical applications or business. Hence, the limitations of the traditional network designs to provide innovative and enhanced services and applications motivated a consensus to integrate all services over packet switching infrastructures, using the Internet Protocol, so as to leverage flexible control and economical benefits in the Next Generation Networks (NGNs). However, the Internet is not capable of treating services differently while each service has its own requirements (e.g., Quality of Service - QoS). Therefore, the need for more evolved forms of communications has driven to radical changes of architectural and layering designs which demand appropriate solutions for service admission and network resources control. This Thesis addresses QoS and network control issues, aiming to improve overall control performance in current and future networks which classify services into classes. The Thesis is divided into three parts. In the first part, we propose two resource over-reservation algorithms, a Class-based bandwidth Over-Reservation (COR) and an Enhanced COR (ECOR). The over-reservation means reserving more bandwidth than a Class of Service (CoS) needs, so the QoS reservation signalling rate is reduced. COR and ECOR allow for dynamically defining over-reservation parameters for CoSs based on network interfaces resource conditions; they aim to reduce QoS signalling and related overhead without incurring CoS starvation or waste of bandwidth. ECOR differs from COR by allowing for optimizing control overhead minimization. Further, we propose a centralized control mechanism called Advanced Centralization Architecture (ACA), that uses a single state-full Control Decision Point (CDP) which maintains a good view of its underlying network topology and the related links resource statistics on real-time basis to control the overall network. It is very important to mention that, in this Thesis, we use multicast trees as the basis for session transport, not only for group communication purposes, but mainly to pin packets of a session mapped to a tree to follow the desired tree. Our simulation results prove a drastic reduction of QoS control signalling and the related overhead without QoS violation or waste of resources. Besides, we provide a generic-purpose analytical model to assess the impact of various parameters (e.g., link capacity, session dynamics, etc.) that generally challenge resource overprovisioning control. In the second part of this Thesis, we propose a decentralization control mechanism called Advanced Class-based resource OverpRovisioning (ACOR), that aims to achieve better scalability than the ACA approach. ACOR enables multiple CDPs, distributed at network edge, to cooperate and exchange appropriate control data (e.g., trees and bandwidth usage information) such that each CDP is able to maintain a good knowledge of the network topology and the related links resource statistics on real-time basis. From scalability perspective, ACOR cooperation is selective, meaning that control information is exchanged dynamically among only the CDPs which are concerned (correlated). Moreover, the synchronization is carried out through our proposed concept of Virtual Over-Provisioned Resource (VOPR), which is a share of over-reservations of each interface to each tree that uses the interface. Thus, each CDP can process several session requests over a tree without requiring synchronization between the correlated CDPs as long as the VOPR of the tree is not exhausted. Analytical and simulation results demonstrate that aggregate over-reservation control in decentralized scenarios keep low signalling without QoS violations or waste of resources. We also introduced a control signalling protocol called ACOR Protocol (ACOR-P) to support the centralization and decentralization designs in this Thesis. Further, we propose an Extended ACOR (E-ACOR) which aggregates the VOPR of all trees that originate at the same CDP, and more session requests can be processed without synchronization when compared with ACOR. In addition, E-ACOR introduces a mechanism to efficiently track network congestion information to prevent unnecessary synchronization during congestion time when VOPRs would exhaust upon every session request. The performance evaluation through analytical and simulation results proves the superiority of E-ACOR in minimizing overall control signalling overhead while keeping all advantages of ACOR, that is, without incurring QoS violations or waste of resources. The last part of this Thesis includes the Survivable ACOR (SACOR) proposal to support stable operations of the QoS and network control mechanisms in case of failures and recoveries (e.g., of links and nodes). The performance results show flexible survivability characterized by fast convergence time and differentiation of traffic re-routing under efficient resource utilization i.e. without wasting bandwidth. In summary, the QoS and architectural control mechanisms proposed in this Thesis provide efficient and scalable support for network control key sub-systems (e.g., QoS and resource control, traffic engineering, multicasting, etc.), and thus allow for optimizing network overall control performance.À medida que as Tecnologias de Informação (TIs) se tornaram parte integrante da nossa sociedade, a expectativa dos cidadãos relativamente ao uso desses serviços também demonstrou um aumento, seja no âmbito das atividades profissionais, de lazer, aplicações de segurança crítica ou negócios. Portanto, as limitações dos projetos de rede tradicionais quanto ao fornecimento de serviços inovadores e aplicações avançadas motivaram um consenso quanto à integração de todos os serviços e infra-estruturas de comutação de pacotes, utilizando o IP, de modo a extrair benefícios económicos e um controlo mais flexível nas Redes de Nova Geração (RNG). Entretanto, tendo em vista que a Internet não apresenta capacidade de diferenciação de serviços, e sabendo que cada serviço apresenta as suas necessidades próprias, como por exemplo, a Qualidade de Serviço - QoS, a necessidade de formas mais evoluídas de comunicação tem-se tornado cada vez mais visível, levando a mudanças radicais na arquitectura das redes, que exigem soluções adequadas para a admissão de serviços e controlo de recursos de rede. Sendo assim, este trabalho aborda questões de controlo de QoS e rede com o objetivo de melhorar o desempenho do controlo de recursos total em redes atuais e futuras, através da análise dos serviços de acordo com as suas classes de serviço. Esta Tese encontra-se dividida em três partes. Na primeira parte são propostos dois algoritmos de sobre-reserva, o Class-based bandwidth Over-Reservation (COR) e uma extensão melhorada do COR denominado de Enhanced COR (ECOR). A sobre-reserva significa a reserva de uma largura de banda maior para o serviço em questão do que uma classe de serviço (CoS) necessita e, portanto, a quantidade de sinalização para reserva de recursos é reduzida. COR e ECOR consideram uma definição dinâmica de sobre-reserva de parâmetros para CoSs com base nas condições da rede, com vista à redução da sobrecarga de sinalização em QoS sem que ocorra desperdício de largura de banda. O ECOR, por sua vez, difere do COR por permitir a otimização com minimização de controlo de overhead. Além disso, nesta Tese é proposto também um mecanismo de controlo centralizado chamado Advanced Centralization Architecture (ACA) , usando um único Ponto de Controlo de Decisão (CDP) que mantém uma visão ampla da topologia de rede e de análise dos recursos ocupados em tempo real como base de controlo para a rede global. Nesta Tese são utilizadas árvores multicast como base para o transporte de sessão, não só para fins de comunicação em grupo, mas principalmente para que os pacotes que pertençam a uma sessão que é mapeada numa determinada árvore sigam o seu caminho. Os resultados obtidos nas simulações dos mecanismos mostram uma redução significativa da sobrecarga da sinalização de controlo, sem a violação dos requisitos de QoS ou desperdício de recursos. Além disso, foi proposto um modelo analítico no sentido de avaliar o impacto provocado por diversos parâmetros (como por exemplo, a capacidade da ligação, a dinâmica das sessões, etc), no sobre-provisionamento dos recursos. Na segunda parte desta tese propôe-se um mecanismo para controlo descentralizado de recursos denominado de Advanced Class-based resource OverprRovisioning (ACOR), que permite obter uma melhor escalabilidade do que o obtido pelo ACA. O ACOR permite que os pontos de decisão e controlo da rede, os CDPs, sejam distribuídos na periferia da rede, cooperem entre si, através da troca de dados e controlo adequados (por exemplo, localização das árvores e informações sobre o uso da largura de banda), de tal forma que cada CDP seja capaz de manter um bom conhecimento da topologia da rede, bem como das suas ligações. Do ponto de vista de escalabilidade, a cooperação do ACOR é seletiva, o que significa que as informações de controlo são trocadas de forma dinâmica apenas entre os CDPs analisados. Além disso, a sincronização é feita através do conceito proposto de Recursos Virtuais Sobre-Provisionado (VOPR), que partilha as reservas de cada interface para cada árvore que usa a interface. Assim, cada CDP pode processar pedidos de sessão numa ou mais árvores, sem a necessidade de sincronização entre os CDPs correlacionados, enquanto o VOPR da árvore não estiver esgotado. Os resultados analíticos e de simulação demonstram que o controlo de sobre-reserva é agregado em cenários descentralizados, mantendo a sinalização de QoS baixa sem perda de largura de banda. Também é desenvolvido um protocolo de controlo de sinalização chamado ACOR Protocol (ACOR-P) para suportar as arquitecturas de centralização e descentralização deste trabalho. O ACOR Estendido (E-ACOR) agrega a VOPR de todas as árvores que se originam no mesmo CDP, e mais pedidos de sessão podem ser processados sem a necessidade de sincronização quando comparado com ACOR. Além disso, E-ACOR introduz um mecanismo para controlar as informações àcerca do congestionamento da rede, e impede a sincronização desnecessária durante o tempo de congestionamento quando os VOPRs esgotam consoante cada pedido de sessão. A avaliação de desempenho, através de resultados analíticos e de simulação, mostra a superioridade do E-ACOR em minimizar o controlo geral da carga da sinalização, mantendo todas as vantagens do ACOR, sem apresentar violações de QoS ou desperdício de recursos. A última parte desta Tese inclui a proposta para recuperação a falhas, o Survivability ACOR (SACOR), o qual permite ter QoS estável em caso de falhas de ligações e nós. Os resultados de desempenho analisados mostram uma capacidade flexível de sobrevivência caracterizada por um tempo de convergência rápido e diferenciação de tráfego com uma utilização eficiente dos recursos. Em resumo, os mecanismos de controlo de recursos propostos nesta Tese fornecem um suporte eficiente e escalável para controlo da rede, como também para os seus principais sub-sistemas (por exemplo, QoS, controlo de recursos, engenharia de tráfego, multicast, etc) e, assim, permitir a otimização do desempenho da rede a nível do controlo global

Design and protection algorithms for path level aggregation of traffic in WDM metro optical networks

Wavelength Division Multiplexing (WDM) promises to offer a cost effective and scalable solution to meet the emerging demands of the Internet. WDM splits the tremendous bandwidth latent in a fiber into multiple non-overlapping wavelength channels, each of which can be operated at the peak electronic rate. Commercial systems with 128 wavelengths and transmission rates of up to 40 Gbps per wavelength have been made possible using state of the art optical technologies to deal with physical impairments. Systems with higher capacities are likely to evolve in the future. The end user requirements for bandwidth, on the other hand, have been ranging from 155 Mbps to 2.5 Gbps. Dedicating a wavelength for each end user will lead to severe underutilization of WDM channels. This brings to forefront the requirement for sharing of bandwidth in a wavelength among multiple end users.;The concept of wavelength sharing among multiple clients is called grooming. Grooming can be done purely at the optical layer (optical grooming) or it can be done with support from the client layer (electronic grooming). The advantage of all optical grooming is the ease of scalability due to its transparency as opposed to electronic grooming which is constrained by electronic bottlenecks. Efforts towards enhancing optical grooming is pursued through increasing optical switching speeds. However, technologies to make optical switches with high speeds, large port counts and low insertion losses have been elusive and may continue to remain so in the near future.;Recently, there have been some research into designing new architectures and protocols focused on optical grooming without resorting to fast optical switching. Typically, this is achieved in three steps: (1) configure the circuit in the form of a path or a tree; (2) use optical devices like couplers or splitters to allow multiple transmitters and/or receivers to share the same circuit; and (3) provide an arbitration mechanism to avoid contention among end users of the circuit. This transparent sharing of the wavelength channel utilizes the network resources better than the conventional low-speed circuit switched approaches. Consequently, it becomes important to quantify the improvement in achieved performance and evaluate if the reaped benefits justify the cost of the required additional hardware and software.;The contribution of this thesis is two fold: (1) developing a new architecture called light-trails as an IP based solution for next generation WDM optical networks, and (2) designing a unified framework to model Path Level Aggregation of Traffic in metrO Optical Networks (PLATOONs). The algorithms suggested here have three features: (1) accounts for four different path level aggregation strategies---namely, point to point (for example, lightpaths), point to multi-point (for example, source based light-trails), multi-point to point (for example, destination based light-trails) and multi-point to multi-point (for example, light-trails); (2) incorporates heterogenous switching architectures; and (3) accommodates multi-rate traffic. Algorithms for network design and survivability are developed for PLATOONs in the presence of both static and dynamic traffic. Connection level dedicated/shared, segregated/mixed protection schemes are formulated for single link failures in the presence of static and dynamic traffic. A simple medium access control protocol that avoids collisions when the channel is shared by multiple clients is also proposed.;Based on extensive simulations, we conclude that, for the studied scenarios, (1) when client layer has no electronic grooming capabilities, light-trails (employing multi-point to multi-point aggregation strategy) perform several orders of magnitude better than lightpaths and (2) when client layer has full electronic grooming capabilities, source based light-trails (employing point to multi-point aggregation strategy) perform the best in wavelength limited scenarios and lightpaths perform the best in transceiver limited scenarios.;The algorithms that are developed here will be helpful in designing optical networks that deploy path level aggregation strategies. The proposed ideas will impact the design of transparent, high-speed all-optical networks.</p

Heterogeneous Wireless Networks: An Analysis of Network and Service Level Diversity

Future wireless systems will be a collection of symbiotic and hierarchical networks that address different aspects of communication needs. This architectural heterogeneity constitutes a network level diversity, where wireless domains can benefit from each other's spare resources in terms of bandwidth and energy. The dissertation investigates the network diversity through particularly interesting scenarios that involve capacity-limited multi-hop ad hoc networks and high-bandwidth wired or wireless infrastructures. Heterogeneity and infrastructures not only exist at the level of networking technologies and architectures, but also at the level of available services in each network domain. Efficient discovery of services across the domains and allocation of service points to individual users are beneficial for facilitating the actual communication, supplying survivable services, and better utilizing the network resources. These concepts together define the service level diversity, which is the second topic studied in our dissertation. In this dissertation, we first focus on a large-scale hybrid network, where a relatively resource abundant infrastructure network overlays a multi-hop wireless network. Using a random geometric random graph model and defining appropriate connectivity constraints, we derive the overall transport capacity of this hybrid network. In the sequel, we dwell upon hybrid networks with arbitrary size and topology. We develop a Quality of Service (QoS) based framework to utilize the joint resources of the ad hoc and infrastructure tier with minimal power exposure on other symbiotic networks that operate over the same radio frequency bands. The framework requires a cross-layer approach to adequately satisfy the system objectives and individual user demands. Since the problem is proven to be intractable, we explore sub-optimal but efficient algorithms to solve it by relying on derived performance bounds. In the last part of the dissertation, we shift our attention from network level diversity to service level diversity. After investigating possible resource discovery mechanisms in conjunction with their applicability to multi-hop wireless environments, we present our own solution, namely Distributed Service Discovery Protocol (DSDP). DSDP enables a highly scalable, survivable, and fast resource discovery under a very dynamic network topology. It also provides the necessary architectural and signaling mechanisms to effectively implement resource allocation techniques