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Results from Running an Experiment as a Service Platform for Mobile Networks
Get PDFIn this paper we present a selection from a vast range of experiments run with MONROE, our experiment as a service platform open to external researchers. We show that the platform can be used to benchmark network performance in a repeatable and controlled manner thanks to the collection of a rich set of geotagged meta- data and the execution of discretionary user experiments. Indeed, with the sheer amount of data collected from 12 commercial mobile operators across Europe, MONROE offers an unprecedented opportunity to monitor, analyze and ultimately improve the status of current and future mobile broadband networks. We also show how flexibly the platform allows combining metadata and experimental data series during the experiments or by means of post-processing, and show results produced by our own experiments as well as by external research groups and developers that have been granted access to the platform.TRUEpu
Four Years Tracking Unrevealed Topological Changes in the African Interdomain
Get PDFThe complete text of this publication is available at: https://doi.org/10.1016/j.comcom.2017.02.014
Paper history: Received 23 August 2016, Revised 22 December 2016, Accepted 19 February 2017, Available online 1 March 2017.Despite extensive studies on the Internet topology, little is still known about the AS level topology of the African Internet, especially when it comes to its IXP substrate. The main reason for this is the lack of vantage points that are needed to obtain the proper information. From 2013 to 2016, we enhanced the RIPE Atlas measurement infrastructure in the region to shed light on both IPv4 and IPv6 topologies interconnecting local ISPs. We increased the number of vantage points in Africa by 278.3% and carried out measurements between them at random periods. To infer results that depict the behavior of ISPs in the region, we propose reproducible traceroute data analysis techniques suitable for the treatment of any set of similar measurements. We first reveal a large variety of ISP transit habits and their dependence on socio-economic factors. We then compare QoS within African countries, European countries, and the US to find that West African networks in particular need to promote investments in fiber networks and to implement traffic engineering techniques. Our results indicate the remaining dominance of ISPs based outside Africa for the provision of intra-continental paths, but also shed light on traffic localization efforts. We map, in our traceroute data, 62.2% of the IXPs in Africa and infer their respective peers. Finally, we highlight the launch of new IXPs and quantify their impacts on end-to-end connectivity. The study clearly demonstrates that to better assess interdomain routing in a continent, it is necessary to perform measurements from a diversified range of vantage points.pu
Early Prediction and Variable Importance of Certificate Accomplishment in a MOOC
Get PDFThe emergence of MOOCs (Massive Open Online Courses) makes available big amounts of data about students' interaction with online educational platforms. This allows for the possibility of making predictions about future learning outcomes of students based on these interactions. The prediction of certificate accomplishment can enable the early detection of students at risk, in order to perform interventions before it is too late. This study applies different machine learning techniques to predict which students are going to get a certificate during different timeframes. The purpose is to be able to analyze how the quality metrics change w
hen the models have more data available. From the
four machine learning techniques applied finally we choose a boosted trees model which provides stability in the prediction over the weeks with good quality metrics. We determine the variables that are most important for the prediction and how they change during the weeks of the course.TRUEpu
Adaptive Scheduling over a Wireless Channel under Constrained Jamming
No full textWe consider in this talk the problem of packet scheduling over an unreliable wireless communication channel. A setting with a single pair of nodes is considered, a sender and a receiver. The sending station transmits packets to a receiving station over the channel that can be jammed, which corrupts the packet being transmitted. The jamming is controlled by a constrained adversary. The constrained power of the adversary is modeled by an Adversarial Queueing Theory (AQT) approach, defined with two main parameters; ρ, the error availability rate, and σ, the maximum batch of errors available to the adversary at any time. In this problem, the scheduling algorithms must decide on the length of the packets to be transmitted, with the objective of maximizing the goodput rate; the rate of successfully transmitted load. It is seen, that even for the simplest settings, finding an optimal algorithm is not trivial, but efficient solutions can be found.FALSEpu
Network Simplification Preserving Bandwidth and Routing Capabilities
Get PDFWe introduce structural transformations that allow simplifying a given network while preserving its original
“bandwidth” and “routing” capabilities, transparently to specific allocations. We minimize a certain objective such as the aggregate capacity of network links, number of nodes, or number of links, in such a way that all the bandwidth that could be routed in the original network can also be routed in the reduced one. This improves cost-efficiency for both inter- and intra-datacenter connections and simplifies network management. We also identify a fundamental tradeoff between extra added capacity and simplicity of representation for a given network. Our analytic results are supported by extensive simulation results on hundreds of real network topologies. One of its results is that by adding 10-30%
extra capacity to evaluated real-world networks one can simplify them to a star topology with a single switch, while all routing and bandwidth allocation decisions on the simplified topology can be mapped back to the original network. This is an important step towards simplifying network management via a reduced virtualized network infrastructure.TRUEpu
On the Energy-Proportionality of Data Center Networks
Get PDFData centers provision industry and end users with the necessary computing and communication resources to access the vast majority of services online and on a pay-as-you-go basis. In this paper, we study the problem of energy proportionality in data center networks (DCNs). Devices are energy proportional when any increase of the load corresponds to a proportional increase of energy consumption. In data centers, energy consumption is concern as it considerably impacts on the operational expenses (OPEX) of the operators. In our analysis, we investigate the impact of three different allocation policies on the energy proportionality of computing and networking equipment for different DCNs, including 2-Tier, 3-Tier and Jupiter topologies. For evaluation, the size of the DCNs varies to accommodate up to several thousands of computing servers. Validation of the analysis is conducted through simulations. We propose new metrics with the objective to characterize in a holistic manner the energy proportionality in data centers. The experiments unveil that, when consolidation policies are in place and regardless of the type of architecture, the size of the DCN plays a key role, i.e., larger DCNs containing thousands of servers are more energy proportional than small DCNs.pu