Robust Energy Management for Green and Survivable IP Networks

Despite the growing necessity to make Internet greener, it is worth pointing out that energy-aware strategies to minimize network energy consumption must not undermine the normal network operation. In particular, two very important issues that may limit the application of green networking techniques concern, respectively, network survivability, i.e. the network capability to react to device failures, and robustness to traffic variations. We propose novel modelling techniques to minimize the daily energy consumption of IP networks, while explicitly guaranteeing, in addition to typical QoS requirements, both network survivability and robustness to traffic variations. The impact of such limitations on final network consumption is exhaustively investigated. Daily traffic variations are modelled by dividing a single day into multiple time intervals (multi-period problem), and network consumption is reduced by putting to sleep idle line cards and chassis. To preserve network resiliency we consider two different protection schemes, i.e. dedicated and shared protection, according to which a backup path is assigned to each demand and a certain amount of spare capacity has to be available on each link. Robustness to traffic variations is provided by means of a specific modelling framework that allows to tune the conservatism degree of the solutions and to take into account load variations of different magnitude. Furthermore, we impose some inter-period constraints necessary to guarantee network stability and preserve the device lifetime. Both exact and heuristic methods are proposed. Experimentations carried out with realistic networks operated with flow-based routing protocols (i.e. MPLS) show that significant savings, up to 30%, can be achieved also when both survivability and robustness are fully guaranteed

Energy management in communication networks: a journey through modelling and optimization glasses

The widespread proliferation of Internet and wireless applications has produced a significant increase of ICT energy footprint. As a response, in the last five years, significant efforts have been undertaken to include energy-awareness into network management. Several green networking frameworks have been proposed by carefully managing the network routing and the power state of network devices. Even though approaches proposed differ based on network technologies and sleep modes of nodes and interfaces, they all aim at tailoring the active network resources to the varying traffic needs in order to minimize energy consumption. From a modeling point of view, this has several commonalities with classical network design and routing problems, even if with different objectives and in a dynamic context. With most researchers focused on addressing the complex and crucial technological aspects of green networking schemes, there has been so far little attention on understanding the modeling similarities and differences of proposed solutions. This paper fills the gap surveying the literature with optimization modeling glasses, following a tutorial approach that guides through the different components of the models with a unified symbolism. A detailed classification of the previous work based on the modeling issues included is also proposed

Safety Critical Wide Area Network Performance Evaluation

The growing importance of real-time computing in numerous applications poses problems for network architectures, especially safety-critical Wide Area Networks (WANs). Assessing network performance in safety-critical real-time systems is difficult, and suggests the use of both human and technical performance criteria because of the importance of both dimensions in safety-critical settings. This research proposes a model that considers both technical and human performance in network evaluation

The paradigm-shift of social spambots: Evidence, theories, and tools for the arms race

Recent studies in social media spam and automation provide anecdotal argumentation of the rise of a new generation of spambots, so-called social spambots. Here, for the first time, we extensively study this novel phenomenon on Twitter and we provide quantitative evidence that a paradigm-shift exists in spambot design. First, we measure current Twitter's capabilities of detecting the new social spambots. Later, we assess the human performance in discriminating between genuine accounts, social spambots, and traditional spambots. Then, we benchmark several state-of-the-art techniques proposed by the academic literature. Results show that neither Twitter, nor humans, nor cutting-edge applications are currently capable of accurately detecting the new social spambots. Our results call for new approaches capable of turning the tide in the fight against this raising phenomenon. We conclude by reviewing the latest literature on spambots detection and we highlight an emerging common research trend based on the analysis of collective behaviors. Insights derived from both our extensive experimental campaign and survey shed light on the most promising directions of research and lay the foundations for the arms race against the novel social spambots. Finally, to foster research on this novel phenomenon, we make publicly available to the scientific community all the datasets used in this study.Comment: To appear in Proc. 26th WWW, 2017, Companion Volume (Web Science Track, Perth, Australia, 3-7 April, 2017

Current Efforts Concerning ICT Security of the Power Grid

GRID is a Coordination Action funded under the Trust and Security objective of the IST Programme of the 6th Framework to achieve consensus at the European level on the key issues involved by power systems vulnerabilities, in view of the challenges driven by the transformation of the European power infrastructure and ICT integration. GRID wants to assess the needs of the EU power sector on these issues, so as to establish a Roadmap for collaborative research in this area. The present report provides a survey on current efforts somewhat related to the objectives of GRID. Similar to GRID, a number of European and US endeavours have attempted in recent years to draw a Road Map so as to coordinate efforts concerning energy transport/distribution research and CIP.JRC.G.6-Sensors, radar technologies and cybersecurit

Semi-Markov Models for Performance Evaluation of Telecommunication Networks in the Presence of Failures

Planning and deployment of next generation telecommunication networks based on the Third Generation Partnership Project IP Multimedia Subsystem (IMS) must take into account the occurrence of random failures causing performance degradations, in order to assess and maintain the Quality of Service offered by telecommunication service providers to their subscribers. In particular, core network signalling servers of IMS can be modelled as repairable multi-state elements where server states correspond to different performance levels. In this paper, we evaluate IMS signalling network performance in terms of the number of sessions handled by the network per time unit, by adopting a semi-Markov model for the IMS servers, which allows as well for non-exponential probability distributions of sojourn times, as often observed in practical network scenarios. Furthermore, a redundancy optimisation problem is solved in an IMS-based realistic scenario, to the aim of minimizing the deployment cost of a telecommunication network with a given availability requirement

Compilation of Development Metrics Applicable to Wave Energy Converters (WECs): Current Status and Proposed Next Steps

As for any novel technology, the need to consider, identify and formulate performance requirements and related assessment criteria has been an important subject in the development of Wave Energy Converters (WECs). These allow the characterisation of each technology through techno-economic indicators, which in turn allow comparisons between different technologies, and an assessment of alternative solutions throughout all the development stages. Such assessment is ideally carried out through the application of metrics, which should comply with several attributes, such as being objective, quantitative, specific, measurable, repeatable, and independent. In the present work, more than 50 metrics to monitor the development of WECs are compiled, explained, and discussed. These metrics are divided in the following evaluation areas: 1) Performance; 2) Reliability; 3) Survivability; 4) Techno-economics. In addition, the important evaluation area of Environmental Impact is briefly discussed concerning the need for common metrics. The compilation summarised in this paper and its discussion aim to provide a practical reference source concerning metrics for WEC development, which is currently unavailable in the published literature in terms of broadness and condensed presentation. Such compilation includes multiple formulations from the wave energy sector and other relatable industries (e.g. wind energy) that are typically diluted among specialist literature, standards, guidelines and recommendations, scientific papers, and project reports. The paper is concluded with a reflection of any salient gaps that are not addressed by current metrics, in a context of accelerating the development of WEC technologies

Regenerator Location Problem and survivable extensions: A hub covering location perspective

Cataloged from PDF version of article.In a telecommunications network the reach of an optical signal is the maximum distance it can traverse before its quality degrades. Regenerators are devices to extend the optical reach. The regenerator placement problem seeks to place the minimum number of regenerators in an optical network so as to facilitate the communication of a signal between any node pair. In this study, the Regenerator Location Problem is revisited from the hub location perspective directing our focus to applications arising in transportation settings. Two new dimensions involving the challenges of survivability are introduced to the problem. Under partial survivability, our designs hedge against failures in the regeneration equipment only, whereas under full survivability failures on any of the network nodes are accounted for by the utilization of extra regeneration equipment. All three variations of the problem are studied in a unifying framework involving the introduction of individual flow-based compact formulations as well as cut formulations and the implementation of branch and cut algorithms based on the cut formulations. Extensive computational experiments are conducted in order to evaluate the performance of the proposed solution methodologies and to gain insights from realistic instances. (C) 2014 Elsevier Ltd. All rights reserved