1,720,978 research outputs found
Towards an automated framework to instantiate virtual networks in OpenFlow-based infrastructures
No full textThe explosion of cloud applications and data-centres technologies has recently renewed the interest of both academic and industrial research community on network virtualisation techniques. The increasing availability of programmable network devices and the pervasive adoption of a software-defined networking approach in all segments of the network are paving the way toward novel virtualisation approaches which aim at improving network management operations while guaranteeing a better utilisation of resources especially when compared to traditional overlay-based techniques widely used in data-centre settings. In this paper, the experience gained by the authors in the development and deployment of an innovative network virtualisation framework on an OpenFlow-based programmable experimental facility is provided and discussed in detail. Despite its specific application to a Future Internet testbed scenario, the proposed architecture is a first step toward a completely automatic management of virtual networks in OpenFlow-based software-defined networks
An Approach to Exposing and Sharing Network Services in Software-Defined Networking
No full textThe ecosystem of SDN controllers and programmable devices is
extremely fragmented: a number of controller platforms and companion
tools is available, each of them based on a very different
set of features. Moreover, most of the SDN controller frameworks
provide a limited set of functionalities to applications that can be
deployed on top (usually leveraging on a set of northbound APIs
Experimental Evaluation of YAMATO, a SDN Control Plane for Joint and Fractional-Joint Switched SDM Optical Networks
No full textManaging (Fractional) Joint Switching will enable the deployment of cost-effective SDM networks. This paper describes a network model and the first control plane implementation handling these paradigms. We show, using an emulated testbed, that the system is responsive and scalable
YAMATO: The First SDN Control Plane for Independent, Joint, and Fractional-Joint Switched SDM Optical Networks
No full textThe deployment of space division multiplexed (SDM) optical networks hinges on this technology being able to offer a beneficial ratio between the expected capacity gains and the resulting cost increase. In order to keep the cost of SDM low, several integrated devices have been proposed to perform the functions of transmission, reception, amplification, and switching; however, little or no work has been carried out in creating a network model to represent their behavior, and in actually managing and controlling them, especially with respect to those devices that are able to jointly switch multiple spatial dimensions. This paper describes YAMATO, the first control plane designed to handle any type of SDM fiber and switching paradigm. To do so, we present a network model capable of encoding any SDM link and node, and describe the design and functions of our network controller, which is based on the OpenDaylight framework. Furthermore, we investigate the additional complexity faced by optical restoration schemes for SDM compared to standard optical networks. We experimentally evaluate the proposed system via an emulated testbed, and report some performance measurements of our implementation
Demonstration of a Hybrid SDN/GMPLS Control Plane for Optical Virtual Private Networks with Restoration Capabilities
No full textCreating Optical Virtual Private Networks (OVPNs) over existing deployments is becoming an operator concern. This paper describes the first hybrid SDN/GMPLS implementation addressing this problem and demonstrates, through an emulated testbed, that the system is responsive and provides OVPN-specific restoration
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
A Proposal for End-to-End QoS Provisioning in Software-Defined Networks
Get PDFThis paper describes a framework application for the control plane of a network infrastructure; the objective is to feature end-user applications with the capability of requesting at any time a customised end-to-end Quality-of-Service profile in the context of dynamic Service-Level-Agreements. Our solution targets current and future real-time applications that require tight QoS parameters, such as a guaranteed end-to-end delay bound. These applications include, but are not limited to, health-care, mobility, education, manufacturing, smart grids, gaming and much more. We discuss the issues related to the previous Integrated Service and the reason why the RSVP protocol for guaranteed QoS did not take off. Then we present a new signaling and resource reservation framework based on the cutting-edge network controller ONOS. Moreover, the presented system foresees the need of considering the edges of the network, where terminal applications are connected to, to be piloted by distinct logically centralised controllers. We discuss a possible inter-domain communication mechanism to achieve the end-to-end QoS guarantee.</jats:p
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