Proactive defragmentation in elastic optical networks under dynamic load conditions

The final publication is available at Springer via http://dx.doi.org/10.1007/s11107-018-0767-7The main weakness of elastic optical networks (EON), under dynamic traffic conditions, stems from spectrum fragmentation. A lot of research efforts have been dedicated during recent years to spectrum defragmentation. In this work, a thorough study about proactive defragmentation is carried out. Effects of the different defragmentation parameters on the EON performance are analyzed, and appropriate values of the defragmentation period, which guarantee suitable network performance while keeping the network control complexity at reasonable values, are obtained by means of extensive simulations. Benefit obtained by applying different defragmentation strategies, in terms of increase in the supported load at a given bandwidth blocking probability, is also reported. Different traffic conditions and network topologies are simulated to assess the validity of the obtained results.Peer ReviewedPostprint (author's final draft

Network Virtualization Over Elastic Optical Networks: A Survey of Allocation Algorithms

Network virtualization has emerged as a paradigm for cloud computing services by providing key functionalities such as abstraction of network resources kept hidden to the cloud service user, isolation of different cloud computing applications, flexibility in terms of resources granularity, and on‐demand setup/teardown of service. In parallel, flex‐grid (also known as elastic) optical networks have become an alternative to deal with the constant traffic growth. These advances have triggered research on network virtualization over flex‐grid optical networks. Effort has been focused on the design of flexible and virtualized devices, on the definition of network architectures and on virtual network allocation algorithms. In this chapter, a survey on the virtual network allocation algorithms over flexible‐grid networks is presented. Proposals are classified according to a taxonomy made of three main categories: performance metrics, operation conditions and the type of service offered to users. Based on such classification, this work also identifies open research areas as multi‐objective optimization approaches, distributed architectures, meta‐heuristics, reconfiguration and protection mechanisms for virtual networks over elastic optical networks

A Study on Reactive and Proactive Push-Pull/Make-Before-Break Defragmentation For Dynamic RMSA

In this thesis, we investigate several defragmentation techniques, with both proactive and reactive triggering strategies, in the context of dynamic Routing, Modulation and Spectrum Assignment (RMSA) in optical flexible networks. Proactive defragmentation is executed periodically or according to some fragmentation degradation thresholds in order to maintain spectral defragmentation at an acceptable level, the defragmentation is independent of the request connection events. Reactive defragmentation, on the other hand, is performed when a new request is blocked due to insufficient spectral resources. In the context of dynamic traffic in a flexible optical network, we looked into different combinations of proactive/reactive push-pull and make-before-break defragmentations. Extensive numerical results show that reactive push-pull defragmentation performs quite well in terms of network throughput and request blocking ratio. Consequently, it is efficient in order to improve network throughput. For proactive push-pull defragmentation, we investigated two different triggering events, namely, time-driven and throughput-driven. We observed that both triggering strategies have a good performance on maintaining an efficient spectrum usage in networks. Throughput-driven strategy performs better when the network is heavily loaded, whereas time-driven strategy is a better option when the network is less loaded

Fairness versus efficiency in spectrum allocation on elastic optical networks

Orientador: Helio WaldmanDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de ComputaçãoResumo: O crescimento do tráfego na rede mundial de computadores tem impulsionado a pesquisa em tecnologias que consigam usar a infraestrutura já instalada da forma mais eficiente possível. Essa infraestrutura é, em maior parte, composta de fibra óptica. Para aumentar sua eficiência, foi proposto que a próxima geração de redes ópticas se utilize do paradigma flexível, que aumenta o aproveitamento do espectro em até 40%. Entretanto, a alocação eficiente de recursos gera diversos problemas, entre eles, a discriminação de classes de acesso para tráfego multiclasses. Dessa forma, nesse trabalho, as políticas de alocação espectral que visam a eliminação da discriminação de classes são estudadas e seu desempenho comparado com as políticas que visam somente a eficiência. Assim, o estudo apresenta uma análise quantitativa do trade-off entre eficiência espectral e imparcialidade na alocação espectral. Os resultados apontam que o uso de imparcialidade pode gerar ganho no tráfego total agregado médio de um sistema óptico para certas configurações e em carga de tráfego altaAbstract: The traffic growth on the global computer network have been boosting the research on technologies that are able to use the installed infrastructure in the most efficient way. This infrastructure is, in most part, composed by optical fiber. To improve its efficiency, it was proposed that the next generation of optical networks uses the flexible paradigm, which improves the spectrum use by up to 40%. However, the efficient use of resources generates several problems, between them, the discrimination of access classes on multiclass traffic. Thus, on this work, the spectrum allocation policies that aim to end the discrimination of classes are studied and their performance are compared with the policies that aim only efficiency. Therefore, the study presents a quantitative analysis on the trade-off between spectral efficiency and fairness on spectrum allocation. The obtained results showed that, by applying fairness in the spectrum allocation, the mean total throughput of the network can be increased for certain settings and high traffic loadMestradoTelecomunicações e TelemáticaMestre em Engenharia Elétrica159677/2015-7CNP

Efficiency and fairness in an elastic optical network under heavy traffic

Orientador: Helio WaldmanDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de ComputaçãoResumo: O crescimento do tráfego na rede mundial de computadores tem impulsionado a pesquisa em tecnologias que consigam usar a infraestrutura já instalada da forma mais eficiente possível. Essa infraestrutura é, em maior parte, composta de fibra óptica. Para aumentar sua eficiência foi proposta uma nova geração de redes ópticas, chamadas redes elásticas, que adotam um paradigma flexível de ocupação do espectro óptico aumentando substancialmente seu aproveitamento. Contudo, um ambiente heterogêneo no qual diferentes classes de tráfego convivem pode levar a uma competição e discriminação de algumas classes em detrimento de outras. Neste trabalho estudamos políticas de alocação espectral que visam garantir um eficiente uso da banda óptica, mantendo uma alta ocupação do espectro e eliminando a discriminação entre classes de acesso em uma rede sob alta carga de tráfegoAbstract: The traffic growth in the global computer network has driven the research on technologies that are able to use the infrastructure already installed as efficiently as possible. This infrastructure is, for the most part, composed of optical networks. In order to increase its efficiency, a new generation of optical networks, called elastic networks, was proposed adopting a flexible paradigm of optical spectrum occupancy, substantially increasing its utilization. However, a heterogeneous environment where different classes of traffic coexist can lead to competition and discrimination of some classes to the detriment of others. This work studies spectral allocation policies aimed at guaranteeing an efficient use of the optical bandwidth, maintaining a high spectral occupation and eliminating the discrimination between access classes in a network under a heavy trafficMestradoTelecomunicações e TelemáticaMestre em Engenharia Elétrica1554016CAPE