Improved performance robustness of DSP-enabled flexible ROADMs free from optical filters and O-E-O conversions

Utilizing Hilbert-pair-based digital filtering, intensity modulation, and passive optical coupling, digital signal processing (DSP) enabled flexible reconfigurable optical add/drop multiplexers (ROADMs) are reported, which are free from optical filters and optical-electrical-optical (O-E-O) conversions and offer excellent flexibility, color-lessness, gridlessness, contentionlessness, adaptability, and transparency to physical-layer network characteristics. In this paper, the ROADM performance robustness against variations in numerous network design aspects is, for the first time to the best of our knowledge, extensively explored in intensity-modulation- and direct-detection-based optical network nodes. Numerical results show that DSPs not only enable the ROADMs to dynamically and flexibly perform add/drop operations at wavelength, subwavelength, and spectrally overlapped orthogonal subband levels but also considerably improve the ROADM performance robustness against variations in modulation formats, transmission system characteristics/impairments, and terminal equipment configurations

Semiconductor optical amplifier based wavelength conversion of Nyquist-16QAM for flex-grid optical networks

We experimentally demonstrate semiconductor opti-cal amplifier (SOA) based wavelength conversion of 3×25 Gbaud Nyquist-16QAM signal for a flex-grid network. The conversion efficiency and power penalty of each of three channels during sin-gle pumped SOA wavelength conversion are studied with respect to three different channel spacings (or frequency grids). The BER performance of all converted channels fall below the FEC thresh-old of 3.8e-3, even with a 50 GHz grid. The results show the trade-off between channel spacing, conversion efficiency and BER power penalty. Closely packed channels, which clearly increase spectral efficiency, are also shown to decrease conversion power penalty, potentially counter balancing increased crosstalk levels. These re-sults can be used to optimize routing and spectrum allocation strategy when SOA wavelength converter(s) are present in the optical link

Experimental Validation of Time-Synchronized Operations for Software-Defined Elastic Optical Networks

Elastic optical networks (EON) have been proposed as a solution to efficiently exploit the spectrum resources in the physical layer of optical networks. Moreover, by centralizing legacy generalized multiprotocol label switching control-plane functionalities and providing a global network view, software-defined networking (SDN) enables advanced network programmability valuable to control and configure the technological breakthroughs of EON. In this paper, we review our recent proposal [Optical Fiber Communication Conf., Los Angeles, California, 2017] of time-synchronized operations (TSO) to minimize disruption time during lightpath reassignment in EON. TSO has been recently standardized in SDN, and here we discuss its implementation using NETCONF and OpenFlow in optical networks. Subsequently, we update our analytical model considering an experimental characterization of the WSS operation time. Then, we extend our previous work with an experimental validation of TSO for lightpath reassignment in a five-node metropolitan optical network test-bed. Results validate the convenience of our TSO-based approach against a traditional asynchronous technique given its reduction of disruption time, while both techniques maintain a similar network performance in terms of optical signal-to-noise ratio and optical power budget

OSNR Aware Composition of an Open and Disaggregated Optical Node and Network

A function programmable optical network has been recently proposed to enhance the flexibility of an optical transport based on architecture-on-demand (AoD). The flexible synthesis of optical node architectures provided by AoD enables an open and disaggregated optical layer thanks to the available deep programmability. However, previous studies have focused on how to synthesize a single node out of switching function blocks, thus neglecting the optical signal-to-noise ratio (OSNR) impact, power imbalance effects due to the diverse set of devices traversed per input–output configuration, and network-wide implications. In this work, we present an optical network-wide function synthesis (ONetFuS), which is an algorithm to compose AoD nodes that consider placement and configuration of both switches and amplifiers. ONeFuS minimizes OSNR degradation and deviation across channels and offers enhanced power balance performance. Moreover, ONetFuS addresses multiple-node scenarios to investigate cascading, transmission distance, and networking effects. We compare the number of optical cross-connections computed by our proposal against solutions in the literature. Results in network scenarios, including the number of components, power balance, OSNR variations, and OSNR penalty reductions, prove the suitability of our proposed ONetFuS for open and functional programmable optical networks

Control Plane in Software Defined Networks and Stateful Data Planes

L'abstract è presente nell'allegato / the abstract is in the attachmen

Análise comparativa entre o custo de implementação e o custo operacional numa rede core óptica

Trabalho final de mestrado para obtenção do grau de Mestre em Engenharia de Electrónica e TelecomunicaçõesCada vez mais os operadores olham para os custos/consumos que as redes core actuais têm, sendo que este assunto tem sido recorrente em investigações académicas nos últimos anos. Actualmente os serviços de rede utilizam uma elevada largura de banda colocando o ónus nos operadores de rede de modo a fazerem uso dos recursos de rede de forma eficiente. Os grupos de standarização estão a fazer um progresso significativo ao tentar passar dos canais ópticos disponíveis, com velocidades de 10, 40 e 100 Gbps, até aos esperados 400 Gbps e ou até 1 Tbps nas redes core. Recorrendo à plataforma de simulação IMB ILOG CPLEX (software que simula modelos matemáticos), este trabalho permitirá efectuar o estudo comparativo entre os diferentes modelos de optimização de custo de implementação e custo operacional para redes core IP (Internet Protocol) sobre WDM (Wavelength Division Multiplexing), com foco em técnicas de encaminhamento eficientes, tal como o bypass óptico. Tendo por base as topologias fixed-grid e flex-grid, as tecnologias em questão possibilitarão a utilização de canais com diferentes velocidades de transmissão da mesma fibra óptica (MLR). De modo a poder-se simular uma abordagem realista, utilizou-se uma rede Alemã fazendo uso da matriz de tráfego IP e da sua previsão de crescimento de tráfego anual (CAGR), segundo o VNI da Cisco, com base em informação estatística. Comparando os diferentes modelos, conclui-se que tanto o custo de implementação como para o operacional nas redes flex-grid, estes são menores nas tradicionais redes fix-grid. Verificou-se que o custo de implementação reduziu 17.0% enquanto que o custo operacional reduziu 175.8%, face às redes fix-grid. As redes flex-grid permitem assim, o transporte de volumes de tráfego mais elevados de forma mais eficiente devido à sua maior capacidade, eficiência energética e espectral dos canais de transmissão associados a este tipo de redes.More and more operators look at the costs / consumptions that current core networks have, and this subject has been recurrent in academic research in recent years. Currently network services use a high bandwidth by placing the burden on network operators to make efficient use of network resources. Standarization groups are making significant progress in moving from the available optical channels, with speeds of 10, 40 and 100 Gbps, up to the expected 400 Gbps and up to 1 Tbps in the core networks. Using the IMB ILOG CPLEX simulation platform, this work will allow the comparative study of the different implementation cost optimization and operational cost models for Wavelength Division Multiplexing (WDM) Internet core networks. efficient routing techniques, such as optical bypass. Based on the fixed-grid and flex-grid topologies, the models in question will allow the use of channels with different transmission speeds of the same optical fiber (MLR). In order to simulate a realistic approach, a German network using the IP traffic matrix and its annual traffic growth forecast (CAGR), according to Cisco's VNI, was used based on statistical information. Comparing the different models, it is concluded that both the implementation cost and the operational cost in the flex-grid networks is lower than in the traditional fix-grid networks. The cost of implementation was reduced to 17.0% while the operational cost reduced 175.8% compared to the fixed grid networks. Flex-grid networks thus allow the transport of higher traffic volumes more efficiently due to their greater capacity, energy efficiency and spectral transmission channels associated with this type of networks.N/

Modelo para establecer la migración de red de transporte óptico para soportar futuros servicios basados en la nube y requerimientos de redes móviles de quinta generación

RESUMEN : El aumento en el número de usuarios y la aparición de tecnologías de acceso móvil y fijas con conexiones de alta velocidad permite a los operadores de red y contenido ofrecer servicios alternos a sus usuarios finales, como es el caso de los servicios basados en la nube como IaaS, SaaS y PaaS, donde un usuario final puede acceder a software o almacenamiento de punta solo con una conexión a internet de alta capacidad, sin necesidad de realizar grandes inversiones en hardware o software. Esto a su vez está forzando a los operadores de contenido a implementar centros de datos regionales para tener el contenido más cerca de los usuarios finales y optimizar las latencias de la red, por lo tanto las tradicionales redes de transporte están migrando hacia redes de interconexión de data centers o redes intercloud para satisfacer las demandas actuales del mercado. El objetivo de este trabajo es plantear una metodología de migración desde las redes de transporte actuales hacia las redes intercloud con el fin de que los operadores adapten sus redes para mantener productivas las inversiones y seguir vigentes en el mercado.ABSTRACT: The increase in the number of users and the appearance of mobile and fixed access technologies with high-speed connections allows network and content operators to offer alternative services to their end users, such as cloud-based services such as IaaS, SaaS and PaaS, where an end user can access software or state-of-the-art storage with only a high-capacity Internet connection, without the need to invest heavily in hardware or software. This in turn is forcing content operators to implement regional data centers to have the content closer to end users and optimize network latencies, therefore traditional transport networks are migrating to interconnection networks. data centers or inter-cloud networks to satisfy thedemand of the market. The objective of this paper is to propose a migration methodology from the current transport networks to the intercloud networks in order for the operators to adapt their networks to take care of the investments and remain in force in the market