Dynamic subcarrier allocation for multipoint-to-point optical connectivity

A mathematical programming model is proposed to dynamically allocate subcarriers in the upstream direction of point-to-multipoint connections based on Digital Subcarrier Multiplexing. Numerical results show significant capital and energy cost reduction.The research leading to these results has received funding from the H2020 B5G-OPEN (G.A. 101016663), the MICINN IBON (PID2020-114135RB-I00), and the ICREA Institution.Peer ReviewedPostprint (author's final draft

Static resource allocation for dynamic traffic

A flexible offline probabilistic (FOP) algorithm is designed to aggressively accommodate random bandwidth traffic demands in long-haul networks. Compared to algorithms that configure demands according to their maximum bandwidth, the FOP algorithm can save 15% of the spectrum used, accommodating over 99% of the throughput demand

Software‐Defined Optical Networking (SDON): Principles and Applications

Featured by the advantages of high capacity, long transmission distance, and low energy consumption, optical network has been deployed widely as the most important infrastructure for backbone transport network. With the development of Internet, datacenter has become the popular infrastructure for cloud computing, which needs to be connected with high bitrate transport network to support heterogeneous applications. In this case, optical network also becomes a promising option for intra and inter‐datacenter networking. In the networking field, software‐defined networking (SDN) has gained a lot of attention from both academic and industry, and it aims to provide a flexible and programmable control plane. SDN is applicable to optical network, and the optical network integrated with SDN, namely software‐defined optical network (SDON), are expected as the future transport solutions, which can provide both high bitrate connectivity and flexible network applications. The principles and applications of SDON are introduced in this chapter

Elastic networks of the future : benefits for the Colombian internal telecommunication network

RESUMEN: El continuo crecimiento de la demanda de datos está dirigiendo la investigación para dar luz a una red eficiente en el uso de la fibra óptica y el espectro radioeléctrico. La próxima generación de redes será el resultado de una convergencia entre el dominio óptico e inalámbrico para reunir cada una de sus virtudes en una vasta red de telecomunicaciones más resiliente y más simplificada. Colombia no estará marginada de estos avances ya que actualmente despliega fibra óptica por gran parte del territorio nacional y por tal motivo debe estar informada de los progresos actuales en lo referente a redes de telecomunicaciones de nueva generación y orientar de mejor forma los lineamientos legales del ministerio de TIC (Tecnologías de la Información y las Comunicaciones) para traer en consecuencia grandes beneficios a la regulación de la red interna de telecomunicaciones en cuanto a lo decretado acerca de los inmuebles de propiedad horizontal. En este trabajo se plasman los avances en investigación concernientes a transmisiones por fibra óptica, incluyendo el nuevo paradigma de redes híbridas de fibra óptica con redes inalámbricas que permitirán simplificar la red global de telecomunicaciones. Las redes elásticas del futuro sugieren que las redes internas de telecomunicaciones serán más reducidas, simples y versátiles, lo cual facilitará la libre competencia entre los proveedores de servicios de comunicaciones, evitando el monopolio de espacios dentro de edificios de propiedad horizontal. Palabras clave: FI-WI, PON, redes elásticas, redes malla, supercanales, WDM.ABSTRACT: The continuous growth in data demand is leading research to bring to light an efficient network using fiber optics and radioelectric spectrum. The next generation of networks will be the result of a convergence between the optical and wireless domain with the purpose to gather all of their virtues in a vast telecommunications network more resilient and more simplified. Colombia will not be marginalized of these advances because actually has deployed optical fiber in most of the country and therefore they must be informed of current progress in terms of new generation of telecommunications networks and guide in a better way the legal guidelines of the Ministry of ICT (Information and Communications Technology) to bring great benefits to the regulation of internal telecommunications network, concerning what was decreed about the immovable of horizontal property. In this paper, research advances are reflected concerning optical fiber transmission, including the new paradigm of hybrid fiber optic networks with wireless networks that will simplify the global telecommunications network. The elastic networks of the future suggest that internal telecommunications networks will be smaller, simple, and versatile, which will facilitate competition between communication service providers, avoiding the monopoly of spaces within horizontal property buildings. Keywords: Elastic networks, FI-WI, mesh networks, PON, superchannels, WDM

An?lise do impacto de t?cnicas de sobreviv?ncia em redes ?pticas el?sticas de telecomunica??es

A blocking in optical networks is an event where a requested is not established due to network unavailability of resources. It is often used as a parameter for evaluate the network performance. A high blocking rate indicates that the network is not suitable for a given traffic demand. Survivability is a characteristic of actual telecommunication networks, which allow the operation even in the event of link or node failures. In order to a network survive, spare capacity is employed to avoid blocking. The amount of spare capacity must be planned in order to cope with the expected performance, costs of maintenance, complexity of control and capital expenditure. In the recent Elastic Optical Networks, the routing and spectrum assignment problem evolved to a more complex problem, that is the routing, modulation and spectrum assignment. This problem imposes new constraints to the traffic engineering task. In this work we investigated the relationship between protection strategies to the network with other properties affected by it. We compare the blocking rate and resource utilization rate considering both shared and dedicated protection strategies. Furthermore, we analyze special characteristics of the blocking events to both type of protection. In the most of simulated networks, the blocking rate of the shared protection was around 0,5 of the dedicated protection. In some cases, the rate was 0,3. With respect to the resource utilization there is not a considerable difference between two strategies, in a absolute perspective. However, bringing the comparsion to blocking rate and link fragmentation, we saw that the impact was very significant. With the dedicated protection, some networks was a fragmentation around 0,8, while in shared protection the fragmentation was around 0,6, 0,5 and 0,3. Using shared protection, the networks Memorex, Metrona and RNP was average load increased by around 50% in comparsion to dedicated protection. These results allow us say that dedicated protection causes a high impact in the network and requires a large amount of resources to allow a equivalent performance.Nas redes ?pticas de telecomunica??es, o bloqueio ? um evento de n?o estabelecimento de uma conex?o requisitada e ? frequentemente utilizado como par?metro de avalia??o do desempenho da rede. Quanto menor o bloqueio, mais a rede est? capacitada a suportar a demanda de tr?fego que recebe. Uma caracter?stica presente nas redes atuais ? a sobreviv?ncia, que possibilita conex?o entre quaisquer n?s da rede, mesmo quando h? uma situa??o de falha. No entanto, a sobreviv?ncia necessita de uma quantidade consider?vel de recursos para ser provida e isto pode impactar na ocorr?ncia de eventos de bloqueio. Tornar uma rede sobrevivente imp?e v?rias tarefas que interferem na sua performance, no custo e tamb?m na complexidade do seu controle. Nas eminentes redes ?ticas el?sticas, o problema de rotear e alocar o tr?fego da rede evoluiu para um problema ainda mais complexo que nas redes fixas tradicionais. Nestas ?ltimas, devem estar satisfeitas as restri??es de continuidade e contiguidade, cuja severidade ? maior que nas anteriores. Considerando que estas novas caracter?sticas podem ocasionar efeitos diferenciados no funcionamento da rede, o objetivo deste estudo foi avaliar a rela??o entre estrat?gias de prote??o e outras propriedades afetadas por estas estrat?gias. Comparamos as taxas de bloqueio e de utiliza??o de recursos para prote??o dedicada e compartilhada de caminho. Tamb?m observamos caracter?sticas espec?ficas dos eventos de bloqueio para as duas estrat?gias de prote??o. Na maioria das redes simuladas, a raz?o da taxa de bloqueio entre prote??o compartilhada e prote??o dedicada ficou em torno de 0,5. Em algumas redes a diferen?a foi ainda maior, chegando a uma raz?o de 0,3. Quanto ? utiliza??o de recursos, n?o verificou-se uma diferen?a consider?vel entre as duas estrat?gias de prote??o, do ponto de vista absoluto de utiliza??o de recursos. Por?m, ao avaliar os efeitos sobre a taxa de bloqueio, fragmenta??o e carga da rede, percebeu-se que o impacto foi grande. A fragmenta??o com prote??o dedicada chegou a 0,8 em algumas redes, enquanto que, na prote??o compartilhada, a fragmenta??o m?xima foi de 0,6. Algumas redes apresentaram fragmenta??o entre 0,3 e 0,5. Al?m disso, as redes Memorex, Metrona e RNP tiveram aumento da carga m?dia suportada em quase 50% com o uso de prote??o compartilhada. Estes resultados nos permitem afirmar que a prote??o dedicada compromete a rede de uma forma muito mais impactante do que a prote??o compartilhada e necessita de um conjunto maior de recursos para manter uma performance equivalente

Cross-layer static resource provisioning for dynamic traffic in flexible grid optical networks

Flexible grid networks need rigorous resource planning to avoid network over-dimensioning and resource over-provisioning. The network must provision the hardware and spectrum resources statically, even for dynamic random bandwidth demands, due to the infrastructure of flexible grid networks, hardware limitations, and reconfiguration speed of the control plane. We propose a flexible online–offline probabilistic (FOOP) algorithm for the static spectrum assignment of random bandwidth demands. The FOOP algorithm considers the probabilistic nature of random bandwidth demands and balances hardware and control plane pressures with spectrum assignment efficiency. The FOOP algorithm uses the probabilistic spectrum Gaussian noise (PSGN) model to estimate the physical-layer impairment (PLI) for random bandwidth traffic. Compared to a benchmark spectrum assignment algorithm and a widely applied PLI estimation model, the proposed FOOP algorithm using the PSGN model saves up to 49% of network resources

Inter-Datacenter Connectivity in Flexgrid-based Optical Networks

The huge energy consumption of datacenters (DC) requires an elastic resource management, e.g. by turning servers off when they are not used or turning them on to satisfy increments in the demand. Thanks to virtualization, jobs (e.g., web applications) can be encapsulated in virtual machines (VM) mixed with other workloads and consolidate them in the most proper server according to their performance goals. Local resource managers in DCs can migrate VMs from one server to another looking for reducing energy consumption while ensuring the committed quality of experience (QoE). Additionally, cloud providers can create DC federations based on a geographically distributed infrastructure so they can manage appropriately green energy resources available in each DC, thus reducing energy expenditure. Scheduling algorithms can perform VM migration not only within a single DC but also transferring a huge amount of raw data from one DC to another to minimize operational costs while ensuring the QoE. Since traffic between DCs is generated by VM migration, the connectivity required between two DCs highly varies along the day, presenting dramatic differences in an hourly time scale. Therefore, using a flexgrid-based optical network to interconnect DCs is an option to be considered since that technology provides fine and multiple granularity. In flexgrid optical networks the available optical spectrum is divided into frequency slices of fixed spectrum width. Optical connections can be allocated into a variable number of these slices, and its capacity can be dynamically managed by allocating or releasing slices provided that the spectrum allocated to an optical connection remain contiguous. Network providers can facilitate the interconnection among federated DCs by allowing them to request connections’ set up on demand with the desired bitrate, while tearing down those connections when they are not needed. With this aim, in the last years, huge standardization work has been done defining control plane architectures and protocols to automate connection provisioning. The Internet Engineering Task Force (IETF) is defining the Application-Based Network Operations (ABNO) architecture, which is based on standard components such as the active stateful Path Computation Element (PCE). This thesis is devoted to characterize, evaluate and analyze the problem providing optimal VM placement so as to minimize operational costs assuming that those costs are dominated by energy and communication costs. To this aim, analytical models to optimize energy consumption in DC federations are provided. Both cloud and core optical network control architectures are explored and new connectivity models for elastic operations are proposed. Mixed integer linear programming models as well as heuristic algorithms are developed and simulations are carried out. More specifically, the main objective has been attained by developing three goals covering different open issues. First we propose the Elastic Operations in Federated Datacenters for Performance and Cost Optimization (ELFADO) problem for scheduling workload and orchestrating federated DCs. A distributed and a centralized approach are studied. Second we propose architectures based on ABNO, using cross-stratum orchestration and carrier SDN, as well as elastic connectivity models supported: the dynamic elastic model and a transfer mode model respectively. Finally, we consider the centralized ELFADO and both the dynamic elastic and transfer mode connectivity models proposed and evaluate their performance

Optimization, Design, and Analysis of Flexible-Grid Optical Networks with Physical-Layer Constraints

The theme of this thesis is the optimization, design, and analysis of flexible-grid optical networks that are constrained by physical-layer impairments (PLIs). We consider three flexible-grid network scenarios. The networks in the first class are static nonlinear transparent backbone networks where physical-layer resources are allocated to each traffic demand. The networks in the second class are traffic-variable nonlinear translucent backbone networks where regenerator sites are necessary to recover optical signals from the accumulated noise in long-distance transmission. The third class is data-center networks based on optical spatial division multiplexing. Within each class, our focus is primarily on an efficient and balanced allocation of network resources. Both optimization formulations and heuristic algorithms are proposed for each class. The contributions of this thesis can thus be categorized into three topics, as outlined below.First, we consider the optimization of network resources in the presence of PLI. The PLI between optical connections is characterized by the Gaussian noise (GN) model and incorporated into resource allocation algorithms. As an example, for a link-level optical communication system, the spectrum usage can be reduced by roughly up to 22% by accurately modelling the PLIs and assigning proper modulation formats and spectrum to optical connections. For resource allocation in the network level, the power spectral density of each optical connection is optimized in addition to the previously mentioned resources.As a second topic, the design of flexible-grid optical networks is studied. Specifically, we consider the regenerator location problem in traffic-variable translucent backbone networks. Due to the constantly changing traffic, the PLIs suffered by optical connections are also stochastic and, thus, have to be handled from a probabilistic perspective. A statistical network assessment process is used to characterize the noise distributions suffered by optical connections on each link, based on which a heuristic algorithm is proposed to select a set of regenerator sites with the minimum blocking probability.Finally, we study the trade-off between the blocking probability and total throughput in the modular data center networks (DCNs) based on different optical spatial division multiplexing switching schemes. This performance trade-off is caused by the coexistence of traffic demands with extremely different data rates and number of requests in DCNs. A heuristic resource allocation algorithm is proposed to enable flexible tuning of the objective function and achieve a balanced network performance