Availability-Guaranteed Service Function Chain Provisioning with Optional Shared Backups

The dynamic provisioning of Service Function Chain (SFC) using Virtual Network Functions (VNFs) is a challenging problem, especially for availability-constrained services. The provisioning of backup resources is often used to ensure that availability requirements are fulfilled. However, the assignment of backup resources should be carefully designed to avoid resource inefficiencies as much as possible.This paper proposes the Optional Backup with Shared Path and Shared Function (OBSPSF) strategy, which aims at improving resource efficiency while fulfilling the availability requirements of SFC requests. The strategy uses optional backup provisioning to ensure that backup resources are assigned only when strictly needed (i.e., when the SFC alone does not meet the availability constraint). Moreover, OBSPSF encourages backup sharing (among both connectivity and backup VNFs) to reduce the backup resource overhead. Results show that the strategy can accommodate orders-of-magnitude more services than benchmark heuristics from the literature

Storage Protection with Connectivity and Processing Restoration for Survivable Cloud Services

The operation and management of software-based communication systems and services is a big challenge for infrastructure and service providers.The challenge is mainly associated with the larger number of configurable elements and the higher dynamicity in the software-based systems compared to the classical ones. On the other hand, the modularity and programmability in software-based networks enabled by technologies like Software Defined Networking (SDN) and Network Function Virtualization (NFV) provide new opportunities for operators to realize advanced network and service management strategies beyond the classical techniques.In our work, we elaborate on these new opportunities and propose a novel strategy for the management of survivable cloud services.In particular, we leverage the flexibility of SDN and NFV to combine proactive protection and reactive restoration mechanisms and we put forward a novel strategy for enhancing the survivability of cloud services. Through comprehensive evaluations, we demonstrate that the proposed strategy offers significant benefits in terms of availability and restorability of services while reducing, at the same time, the overhead caused by the relocation of cloud services in case of failures

Restauração de serviços em nuvem óptica: uma abordagem tolerante à degradação de banda e ao atraso de restauração

Este artigo, aborda o problema de restauração de serviços na nuvem  com infraestrutura óptica na presença de falha em um único enlace. O algoritmo proposto, denominado R3D, leva em consideração dois parâmetros especificados em classes de serviço (tolerância ao atraso na restauração e degradação de banda passante) para fazer melhor uso dos recursos ópticos disponíveis durante o processo de restauração. Resultados, obtidos através de simulação, demonstram melhorias significativas na capacidade de restauração de serviços sem impactar de forma negativa a probabilidade de bloqueio

Mechanisms for service-oriented resource allocation in IoT

Albeit several IoT applications have been recently deployed in several fields, including environment and industry monitoring, Smart Home, Smart Hospital and Smart Agriculture, current deployments are mostly host-oriented, which is undoubtedly limiting the attained benefits brought up by IoT. Indeed, future IoT applications shall benefit from service-oriented communications, where the communication establishment between end-points is not dependent on prior knowledge of the host devices in charge of providing the service execution. Rather, an end-user service execution request is mapped into the most suitable resources able to provide the requested service. Furthermore, this model is a key enabler for the design of future services in Smart Cities, e-Health, Intelligent Transportation Systems, among other smart scenarios. Recognized the benefits of this model in future applications, considerable research effort must be devoted for addressing several challenges yet unsolved, such as the ones brought up by the high dynamicity and heterogeneity inherent to these scenarios. In fact, service-oriented communication requires an updated view of available resources, mapping service requests into the most suitable resources taking several constraints and requirements into account, resilience provisioning, QoS-aware service allocation, just to name a few. This thesis aims at proposing and evaluating mechanisms for efficient resource allocation in service-oriented IoT scenarios through the employment of two distinct baseline technologies. In the first approach, the so-called Path Computation Element (PCE), designed to decouple the host-oriented routing function from GMPLS switches in a centralized element, is extended to the service-oriented PCE (S-PCE) architecture, where a service identifier (SID) is used to identify the service required by an end-user. In this approach, the service request is mapped to one or a set of resources by a 2-steps mapping scheme that enables both selection of suitable resources according to request and resources characteristics, and avoidance of service disruption due to possible changes on resources¿ location. In the meantime, the inception of fog computing, as an extension of the cloud computing concept, leveraging idle computing resources at the edge of the network through their organization as highly virtualized micro data centers (MDC) enabled the reduction on the network latency observed by services launched at edge devices, further reducing the traffic at the core network and the energy consumption by network and cloud data center equipment, besides other benefits. Envisioning the benefits of the distributed and coordinated employment of both fog and cloud resources, the Fog-to-Cloud (F2C) architecture has been recently proposed, further empowering the distributed allocation of services into the most suitable resources, be it in cloud, fog or both. Since future IoT applications shall present strict demands that may be satisfied through a combined fog-cloud solution, aligned to the F2C architecture, the second approach for the service-oriented resource allocation, considered in this thesis, aims at providing QoS-aware resource allocation through the deployment of a hierarchical F2C topology, where resource are logically distributed into layers providing distinct characteristics in terms of network latency, disruption probability, IT power, etc. Therefore, distinct strategies for service distribution in F2C architectures, taking into consideration features such as service transmission delay, energy consumption and network load. Concerning the need for failure recovery mechanisms, distinct demands of heterogeneous services are considered in order to assess distinct strategies for allocation of protection resources in the F2C hierarchy. In addition, the impact of the layered control topology on the efficient allocation of resources in F2C is further evaluated. Finally, avenues for future work are presented.Aunque son ya varias las aplicaciones que se han desarrollado en el área de IoT, especialmente en el campo ambiental, Smart Home o Smart Health, las implementaciones actuales son en su mayoría ¿host-oriented¿, lo que sin duda limita sus potenciales beneficios. Una posible estrategia para reducir esos efectos negativos se centra en que las futuras aplicaciones se beneficien de las comunicaciones orientadas a servicios, ¿service-oriented¿, donde el establecimiento de comunicación entre puntos finales no depende del conocimiento previo de los hosts a cargo de proporcionar la ejecución del servicio. En este escenario, una solicitud de ejecución de servicio se asigna a los recursos más adecuados capaces de proporcionar el servicio solicitado. Este modelo se considera clave para el despliegue de futuros servicios en Smart Cities, e-Health, Intelligent Transportation Systems, etc. Reconocidos los beneficios de este modelo en las aplicaciones futuras, un substancial esfuerzo de investigación es necesario para abordar varios desafíos aún no resueltos, como los surgidos por la alta dinámica y heterogeneidad inherente a estos escenarios. De hecho, la comunicación service-oriented requiere una vista actualizada de los recursos disponibles, así como la asignación de solicitudes de servicio en los recursos más adecuados teniendo en cuenta varias restricciones y requisitos. Esta tesis tiene como objetivo proponer y evaluar mecanismos para la asignación eficiente de recursos en escenarios IoT orientados a servicios a través del empleo de dos tecnologías básicas distintas. En el primer enfoque, el llamado Path Computation Element (PCE), diseñado para desacoplar la función de enrutamiento de los conmutadores GMPLS hacia un elemento centralizado, se extiende generando la arquitectura service-oriented PCE (S-PCE). En S-PCE se utiliza un identificador de servicio (SID) para identificar el servicio requerido por un usuario final, y la solicitud se asigna, bien a uno o bien a un conjunto de recursos, mediante un esquema de asignación de 2 pasos que permite la selección de los recursos adecuados, evitando la interrupción del servicio debido a posibles cambios en la ubicación de los recursos. Mientras tanto, el inicio de Fog computing, como una extensión de Cloud computing, basado conceptualmente en aprovechar la infraestructura y los recursos inactivos en el extremo de la red a través de su organización como micro data centers (MDC), ha supuesto la reducción de la latencia de la red para los servicios lanzados por dispositivos localizados en el extremo de la red, reduciendo el tráfico en el centro de la red (backbone) así como el consumo de energía, además de otros beneficios. Asumiendo las ventajas de la utilización distribuida y coordinada de los recursos fog y cloud, la arquitectura Fog-to-Cloud (F2C) ha sido recientemente propuesta, destinada a potenciar la asignación distribuida de servicios en los recursos más adecuados, sea en cloud, fog o ambos. Dado que las futuras aplicaciones IoT deben presentar demandas que podrían ser satisfechas a través de una solución alineada con la arquitectura F2C, el segundo enfoque para la asignación de recurso orientado a servicio, considerado en esta tesis, tiene como objetivo proporcionar una asignación de recursos mediante el despliegue de una topología F2C, donde los recursos se distribuyen lógicamente en capas que proporcionan características distintas en términos de latencia de red, probabilidad de interrupción, etc. Así, se proponen distintas estrategias para la distribución de servicios, teniendo en cuenta características tales como QoS y consumo de energía. Con respecto a la necesidad de mecanismos de recuperación de fallos, se evalúan distintas estrategias para la asignación de recursos de protección en la jerarquía F2C. Además, se evalúa el impacto de la topología de control en capas sobre la asignación eficiente de recursos en F2C. Finalmente, las sugerencias para trabajos futuros son presentadas

Dimensioning Optical Clouds with Shared-Path Shared-Computing (SPSC) Protection

Service relocation represents a promising strategy to provide flexible and resource efficient resiliency from link failures in the optical cloud environment. However, when a failure affects a node hosting a datacenter (DC), service relocation from the affected DC is not possible. One alternative to protect against DC failures relies on using design strategies that duplicate the IT (i.e., storage and processing) resources in a backup DC at the expense of increasing resource overbuild (i.e., cost) of the network. This work proposes a dimensioning strategy based on the shared-path shared-computing (SPSC) concept able to protect against any single link, server, or DC failure scenario with minimal resource overbuild for the network and IT infrastructures. SPSC is based on the intuition that only storage units need complete replication in backup DC, while processing units can be instantiated only after the occurrence of a failure, leaving the design strategy some leeway to minimize their number. As result, the proposed SPSC design shows a considerable reduction in the amount of backup resources when compared to the dedicated protection strategies.QC 20170704</p

Energy Efficient Network Function Virtualisation in 5G Networks

Once the dust settled around 4G, 5G mobile networks become the buzz word in the world of communication systems. The recent surge of bandwidth-greedy applications and the proliferation of smart phones and other wireless connected devices has led to an enormous increase in mobile traffic. Therefore, 5G networks have to deal with a huge number of connected devices of different types and applications, including devices running life-critical applications, and facilitate access to mobile resources easily. Therefore given the increase in traffic and number of connected devices, intelligent and energy efficient architectures are needed to adequately and sustainably meet these requirements. In this thesis network function virtualisation is investigated as a promising paradigm that can contribute to energy consumption reduction in 5G networks. The work carried out in this thesis considers the energy efficiency mainly in terms of processing power consumption and network power consumption. Furthermore, it considers the energy consumption reduction that can be achieved by optimising the locations of virtual machines running the mobile 5G network functions. It also evaluates the consolidation and pooling of the mobile resources. A framework was introduced to virtualise the mobile core network functions and baseband processing functions. Mixed integer linear programming optimisation models and heuristics were developed minimise the total power consumption. The impact of virtualisation in the 5G front haul and back haul passive optical network was investigated by developing MILP models to optimise the location of virtual machines. A further consideration is caching the contents close to the user and its impact on the total power consumption. The impact of a number of factor on the power consumption were investigated such as the total number of active users, the backhaul to the fronthaul traffic ratio, reduction/expansion in the traffic due to baseband processing, and the communication between virtual machines. Finally, the integration of network function virtualisation and content caching were introduced and their impact on improving the energy efficiency was investigated

Satellite Communications

This study is motivated by the need to give the reader a broad view of the developments, key concepts, and technologies related to information society evolution, with a focus on the wireless communications and geoinformation technologies and their role in the environment. Giving perspective, it aims at assisting people active in the industry, the public sector, and Earth science fields as well, by providing a base for their continued work and thinking

Feasibility study for a numerical aerodynamic simulation facility. Volume 1

A Numerical Aerodynamic Simulation Facility (NASF) was designed for the simulation of fluid flow around three-dimensional bodies, both in wind tunnel environments and in free space. The application of numerical simulation to this field of endeavor promised to yield economies in aerodynamic and aircraft body designs. A model for a NASF/FMP (Flow Model Processor) ensemble using a possible approach to meeting NASF goals is presented. The computer hardware and software are presented, along with the entire design and performance analysis and evaluation