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The Sliceable Bandwidth-Variable Transponder (SBVT) enables greater flexibility in elastic optical networks (EON), providing energy efficiency and reducing the resource wastage. Another feature offered by SBVTs is the ability to perform optical grooming. Along with electric grooming and a multilevel adaptive modulation, it provides many possibilities in dynamic traffic engineering. A key problem is how to coordinate all these features while promoting energy efficiency and good network performance. In this paper, an unprecedented integer linear programming (ILP) model is developed to optimally solve this problem. The model covers all traffic engineering characteristics in translucent SBVT enabled EONs with electrical and optical grooming for dynamic traffic scenarios. Due to the non-scalability of the ILP model, a corresponding heuristic algorithm based on the auxiliary graph (AG) model is proposed. It can support various traffic engineering policies for different purposes by adjusting the weights of AG edges. Comprehensive comparisons are performed for the ILP model, the AG heuristic, and other online algorithms from the literature. Numerical results show that the AG heuristic provides a gain of two orders of magnitude in the bandwidth blocking ratio and achieves a gain of up to 51% in energy efficiency compared to literature proposals.

Software Defined Networks (SDN) emerged as a new paradigm for network management, defining an architecture the physically decouples the control and data planes. An SDN architecture based on a central controller does not scale and neither is fault-tolerant since it presents a single point of failure. Distributed SDN controllers based on an eventually consistent model for the network state also bring serious drawbacks: a complex programming model for network applications; and it can lead to network anomalies. Consequently, solutions considering a consistent model for the network state are emerging. In these approaches, the distributed controllers use a consistent and fault-tolerant data store that keeps relevant network and applications state. Unfortunately, these approaches do not consider security requirements for the SDN. This work aims to design, implement and evaluate a secure and consistent model for the control plane based on DepSpace, a secure tuple space implementation used to coordinate distributed processes. Experimental results show the practical feasibility of the proposed architecture.

O consumo energético nas redes de núcleo atualmente é impactado pelas aplicações de Bulk Data Transfer (BDT) entre os principais Centros de Dados (CDs) da Internet. Isso ocorre porque essas aplicações consomem a maior parte dos recursos disponíveis e o fazem por longos períodos de tempo. Devido ao aumento do tráfego na rede, que ocorre a cada ano, um dos principais desafios para os provedores de serviço em nuvem é a eficiência energética. Para servir à crescente demanda, o paradigma das Redes Ópticas Elásticas (EON) têm sido proposto com o objetivo de atender requisições com maior flexibilidade, aproveitando melhor o espectro de frequência. Este artigo propõe a solução Energy Efficient Aware-BDT in EON (EEABE), um algoritmo de Roteamento e Alocação de Espectro (RSA) ciente de eficiência energética para realizar BDT inter-CD (ICD), que é capaz de escalonar requisições BDT e implementar a técnica de sleep mode para reduzir o consumo energético dos elementos comutadores na rede óptica.

Elastic optical networks enter as a promising technology for the future of high-capacity networks. Its features provide flexibility and superior scalability in spectrum allocation following the growing demands of Internet traffic. In this letter, we propose a novel approach to address the routing, modulation level, and spectrum allocation (RMLSA) problem through the use of a distance-adaptive modulation scheme that enables the routing of traffic through multiple hops in virtual topology, enabling smoothing out the spectrum continuity and transmission distance constraints. The results showed that the use of the proposed scheme provide a gain of up to 82% in the bandwidth blocking rate using 7% less spectral resources in the network compared with the literature. This proposal opens a new avenue for future research, allowing new solutions for RMLSA problem.

The technology used for data transmission in optical networks is going through significant changes in response to the rapid growth of Internet traffic and emerging high performance applications, boosting research on how to satisfy the increasing demands with the available resources. In this scenario, the elastic optical networks paradigm enables improved provisioning through flexibility and scalability in spectrum assignment. This work proposes data and optical grooming and the use of spectral modulation control as a solution to the Routing, Modulation Level, and Spectrum Allocation problem in a dynamic traffic context. The proposed algorithm obtains the greatest spectrum aggregation possible using higher modulation levels through multiple hops in the virtual topology. Experiments show that this approach results in reduced blocking without impacting the use of the network's resources.

Dissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Exatas, Departamento de Ciência da Computação, 2015. A tecnologia de redes ópticas elásticas surge como uma solução promissora para o futuro da transmissão óptica de alta velocidade. Suas características proporcionam uma flexibilidade e escalabilidade superior na alocação de espectro para os diversos serviços emergentes acompanhando a crescente demanda do tráfego da Internet. Em redes ópticas elásticas as demandas de tráfego são transmitidas usando um número arbitrário de subportadoras OFDM, e um nível de modulação adequado, levando em conta a distância de transmissão. Esta dissertação descreve as principais características do paradigma de redes ópticas elásticas, apresenta as principais linhas de pesquisa encontradas na literatura e propõe soluções para o problema de roteamento e atribuição de espectro com modulação adaptativa (Routing, Modulation Level, and Spectrum Allocation - RMLSA) que visam potencializar o uso da modulação adaptativa com roteamento em múltiplos saltos para o cenário dinâmico de tráfego. Dentre as soluções propostas destacam-se (i) uma abordagem RMLSA que procura realizar a maior quantidade de agregação de tráfego possível usando os níveis de modulação mais altos da rede e (ii) a criação de um esquema de modulação adaptativa, acoplável a qualquer algoritmo RSA, que viabiliza o roteamento do tráfego através de múltiplos saltos na topologia virtual. Os resultados obtidos apresentam uma redução significativa na taxa de bloqueio para diversas soluções RSA da literatura sem comprometer a utilização dos recursos na rede. The elastic optical networks technology emerges as a promising solution for the future of high-speed optical transmission. It provides flexibility and superior capability in spectrum allocation for the various emerging services along the increasing demand of Internet traffic. In Elastic Optical Networks the traffic demands are transmitted using an arbitrary number of OFDM sub carriers, and a suitable modulation level, taking into consideration the transmission distance. This dissertation describes the main characteristics of the Elastic Optical Network paradigm, presents the main areas of research in the literature and proposes solutions that solve the Routing, Level Modulation, and Spectrum Allocation (RMLSA) problem which seeks enhancing the use of adaptive modulation with multihop routing in the dynamic traffic scenario. Among the solutions developed stands out (i) an RMLSA approach that seeks to achieve the greatest possible amount of traffic grooming using the highest modulation levels in network and (ii) the creation of an adaptive modulation scheme, that work along with any RSA algorithm, that enables the multihop routing traffic. The results showed an important reduction in blocking rate for various RSA approaches from the literature without compromising the use of resources in the network.

A VoIP communication infrastructure may need to serve a substantial number of users with an acceptable voice quality. This paper investigates the suitability of the Asterisk PBX server to provide VoIP communication capabilities with an acceptable Mean Opinion Score (MOS) quality to a large number of users. The blocking probability metric is used to measure the capacity of the PBX server while MOS is used to assess the quality of the voice calls. Analytical results show the suitability of the Erlang-B model in characterizing the capacity of the Asterisk PBX server considered in this work. Experimental results have shown that the Asterisk PBX can effectively handle more than 160 concurrent voice calls with a blocking probability of less than 5% while providing voice calls with average MOS above 4.