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Virtualization is defined as the process consisting of building a virtual resource on top of one or several physical resources, depending on the selected paradigm: aggregation or partitioning. From the net- working perspective, over the recent years virtualization became a hot topic in networking research, although the term is not new, neither for networking nor for Information Technology (IT). In virtualization environments, the most significant challenge to be addressed is the virtual infrastructure allocation or embedding one. The problem appears over any networking technology, from wired to wireless domains, including converged physical infrastructures as well as coupled IT and networking infrastructures. This problem has re-gained importance in the last years due to the emergence of novel software- based abstractions, which provide fully-operational interfaces on top of those virtual resources, enabling the emergence of novel business models. The election of the physical resources upon which the virtual infrastructure will be instantiated becomes fundamental for the virtual infrastructure operation in those virtualized environments, i.e. the election of the physical resources over which the virtual ones will be allocated. In fact, the virtual infrastructure allocation system might be seen as a policy-based system, where, based on the physical infrastructure available, and the set of requests, it will create different virtual infrastructures as a function of the policy, which will indicate the metric to optimize when creating those Virtual Infrastructures (VIs). For example, the infrastructure provider, who is responsible for leasing those virtual infrastructures, may want to optimize the economical cost of the different instantiated virtual slices, or even the overall energy consumption of the slices. The problem acquires different dimensions when considering heterogeneous resources (e.g. optical network resources and wireless resources) in order to create cros, La virtualización se define como el proceso consistente en la construcción de recursos lógicos o virtuales sobre uno o varios elementos físicos, dependiente del paradigma seleccionado: agregación o partición. Desde la perspectiva de la red, en los últimos años la virtualización se ha convertido en un tema recurrente, aunque el término virtualización no sea algo nuevo en entornos de red y entornos IT. El problema más significativo a resolver, aunque no el único, en entornos donde se considera la virtualización es el problema de asignación de recursos virtuales sobre los físicos, esto es, decidir qué recursos de la capa física se asignan a las distintas peticiones de infraestructuras virtuales. El problema aparece sobre distintas tecnologías de red, desde redes fijas hasta redes de acceso sin cable, incluyendo dominios integrados acceso metro, y recursos de computación y almacenamiento integrados con la red. El problema ha vuelto a actualizarse y ganar más importancia aún en los últimos años con la aparición de nuevas abstracciones basadas en software, las cuáles proveen interfaces completamente operables sobre los recursos virtuales, al mismo tiempo que se habilitan nuevos modelos de negocio.Por lo tanto, la selección de los recursos físicos sobre los que se construirán e instanciarán las infraestructuras virtuales se convierte en un elemento fundamental para la operación efectiva y eficiente en entornos virtualizados. De hecho, el sistema de virtualización se puede entender cómo un sistema basado en políticas, en el cuál, a partir de una descripción de la infraestructura física y un conjunto de peticiones de infraestructuras virtuales, se crearán diferentes infraestructuras virtuales en función de la política, que en esencia indicará la métrica a ser optimizada en el sistema cuándo se crean las distintas infraestructuras virtuales. Además del análisis del estado del arte del problema de la virtualización, centrado en redes ópticas y entornos donde los recursos IT se, Postprint (published version)

The Cloud Enabled Small Cell (CESC) concept proposed in EU funded project SESAME has emerged as a promising solution to form a multi-tenant, multi-service architecture at the network edge according to 5G needs. It allows several operators/service providers to engage in a sharing model of both radio access capacity and Mobile Edge Computing (MEC) capabilities. From a business perspective, the shared ecosystem guarantees benefits such as easy system upgrades and CAPEX/OPEX reduction. However, depending on the adapted model which is reflected at Service Level Agreement (SLA) between involved stakeholders, cost and benefit of each party are subject to change. This paper is an effort to identify and analyse different radio and cloud models and pricing schemes for the joint provisioning of radio access capacity and MEC services in a multi-tenant Radio Access Network (RAN)., Peer Reviewed, Postprint (published version)

Software-Defined Networking and Network Functions Virtualisation has brought a revolution within the telecom market landscape. Initial proof-of-concept prototypes for NFV-enabled solutions are being developed at the same time SDN models are identified as the futures solutions within the telecom realm. We provide in this article an overview of the SDN/NFV technologies over optical networks, as well as we provide the first formalisation model for the virtual network function complex scheduling problem. The article aims at being used as starting point in order to optimally solve the scheduling problem of virtual network functions that compose network services to be provisioned within the SDN paradigm., Postprint (published version)

Cloud computing service emerged as an essential component of the Enterprise IT infrastructure. Migration towards a full range and large-scale convergence of Cloud and network services has become the current trend for addressing requirements of the Cloud environment. Our approach takes the infrastructure as a service paradigm to build converged virtual infrastructures, which allow offering tailored performance and enable multi-tenancy over a common physical infrastructure. Thanks to virtualization, new exploitation activities of the physical infrastructures may arise for both transport network and Data Centres services. This approach makes network and Data Centres' resources dedicated to Cloud Computing to converge on the same flexible and scalable level. The work presented here is based on the automation of the virtual infrastructure provisioning service. On top of the virtual infrastructures, a coordinated operation and control of the different resources is performed with the objective of automatically tailoring connectivity services to the Cloud service dynamics. Furthermore, in order to support elasticity of the Cloud services through the optical network, dynamic re-planning features have been provided to the virtual infrastructure service, which allows scaling up or down existing virtual infrastructures to optimize resource utilization and dynamically adapt to users' demands. Thus, the dynamic re-planning of the service becomes key component for the coordination of Cloud and optical network resource in an optimal way in terms of resource utilization. The presented work is complemented with a use case of the virtual infrastructure service being adopted in a distributed Enterprise Information System, that scales up and down as a function of the application requests. © 2014 Elsevier B.V., Peer Reviewed, Postprint (published version)

Optical network infrastructures can be partitioned into multiple parallel, dedicated virtual networks for a physical infrastructure sharing purpose. However, different transport technologies may impact in both the amount and the characteristics of the different virtual instances that can be built on top of a single physical infrastructure. To analyse the impact of the transport technology in this regard, we present exact Integer Linear Programming (ILP) formulations that address the off-line problem of optimally allocate a set of virtual networks in two kind of substrates: wavelength switching and spectrum switching. Both formulations serve the purpose to provide opaque transport services from the virtual network point of view, where electronic terminations are assumed in the virtual network nodes. We carry out a series of experiments to validate the presented formulations and determine which is the impact of both substrates in the number of virtual networks that can be optimally allocated in the transport network., Postprint (author’s final draft)

This paper presents a multi-tenancy model based on infrastructure resource capability virtualisation. The model, namely Resources, Ownership, Roles and Actors or RORA, approaches network and IT infrastructure virtualisation seamlessly, thus enabling complex provisioning workflows for Cloud services and network services attached., Peer Reviewed, Postprint (published version)

MANTICORE es un proyecto cuyos principales objetivos son: Proveer de un servicio que permita gestionar y configurar las redes IP de un usuario o organización. Mediante la aplicación, el propietario de la red IP debe ser capaz de realizar la gestión de sus redes IP. En este sentido, debe ser capaz de crear ó eliminar redes IP; debe ser capaz de decidir qué recursos forman qué redes; así como también debe ser capaz de decidir qué direccionamiento usan sus redes ó que protocolos de enrutamiento configura. Además, también ha de ser posible para dos usuarios distintos realizar peering entre sus redes IP. Proveer de un servicio mediante el cuál diversas organizaciones puedan compartir recursos entre otras. El caso más claro en el que queda latente este servicio, es cuando, por ejemplo, un proveedor de infraestructura física quiere ceder un conjunto de sus recursos a un proveedor de servicio ú a cualquier otra organización. Proveer de un servicio para gestionar y configurar dispositivos de red que trabajen a nivel 3 del modelo OSI. El usuario ha de ser capaz de crear particiones lógicas de un mismo dispositivo físico. Por ejemplo, en una interfaz de tipo Fast Ethernet, mediante MANTICORE, el usuario ha de poder crear interfaces lógicas basadas en vlan-id. Además, uno de los objetivos principales y más destacados, desde el punto de vista de la investigación, de este proyecto es la posibilidad que tiene el usuario de crear enrutadores lógicos dentro de un mismo enrutador; aprovechando así al máximo los recursos ofrecidos por el dispositivo y generando, al mismo tiempo, un aislamiento entre enrutadores lógicos que facilita el hecho de que distintas organizaciones compartan el mismo sustrato físico.