34 research outputs found

    Scalable Layer-2/Layer-3 Multistage Switching Architectures for Software Routers

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    Software routers are becoming an important alternative to proprietary and expensive network devices, because they exploit the economy of scale of the PC market and open-source software. When considering maximum performance in terms of throughput, PC-based routers suffer from limitations stemming from the single PC architecture, e.g., limited bus bandwidth, and high memory access latency. To overcome these limitations, in this paper we present a multistage architecture that combines a layer-2 load-balancer front-end and a layer-3 routing back-end, interconnected by standard Ethernet switches. Both the front-end and the back-end are implemented using standard PCs and open- source software. After describing the architecture, evaluation is performed on a lab test-bed, to show its scalability. While the proposed solution allows to increase performance of PC- based routers, it also allows to distribute packet manipulation functionalities, and to automatically recover from component failures

    COVID‑19 mitigation by digital contact tracing and contact prevention (app‑based social exposure warnings)

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    A plethora of measures are being combined in the attempt to reduce SARS-CoV-2 spread. Due to its sustainability, contact tracing is one of the most frequently applied interventions worldwide, albeit with mixed results. We evaluate the performance of digital contact tracing for different infection detection rates and response time delays. We also introduce and analyze a novel strategy we call contact prevention, which emits high exposure warnings to smartphone users according to Bluetooth-based contact counting. We model the effect of both strategies on transmission dynamics in SERIA, an agent-based simulation platform that implements population-dependent statistical distributions. Results show that contact prevention remains effective in scenarios with high diagnostic/response time delays and low infection detection rates, which greatly impair the effect of traditional contact tracing strategies. Contact prevention could play a significant role in pandemic mitigation, especially in developing countries where diagnostic and tracing capabilities are inadequate. Contact prevention could thus sustainably reduce the propagation of respiratory viruses while relying on available technology, respecting data privacy, and most importantly, promoting community-based awareness and social responsibility. Depending on infection detection and app adoption rates, applying a combination of digital contact tracing and contact prevention could reduce pandemic-related mortality by 20–56%.publishedVersionFil: Soldano, GermĂĄn J. Universidad Nacional de CĂłrdoba. Facultad de Ciencias QuĂ­micas; Argentina.Fil: Soldano, GermĂĄn J. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Instituto de Investigaciones en FĂ­sico-quĂ­mica de CĂłrdoba; Argentina.Fil: Fraire Juan A. Universidad Nacional de CĂłrdoba. Facultad de Ciencias Exactas, FĂ­sicas y Naturales; Argentina.Fil: Fraire Juan A. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Instituto de Estudios Avanzados en ingenierĂ­a y TecnologĂ­a; Argentina.Fil: Fraire Juan A. Saarland University. Saarland Informatics Campus; SaarbrĂŒcken, Germany.Fil: Finochietto, Jorge M. Universidad Nacional de CĂłrdoba. Facultad de Ciencias Exactas, FĂ­sicas y Naturales; Argentina.Fil: Finochietto, Jorge M. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Instituto de Estudios Avanzados en ingenierĂ­a y TecnologĂ­a; Argentina.Fil: Quiroga; Rodrigo. Universidad Nacional de CĂłrdoba. Facultad de Ciencias QuĂ­micas; Argentina.Fil: Quiroga; Rodrigo. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Instituto de Investigaciones en FĂ­sico-quĂ­mica de CĂłrdoba; Argentina

    Short-term Fairness in Slotted WDM Rings

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    Single-hop WDM ring networks are promising architectures for future broadband access and metro networks. However, ring networks exhibit significant fairness issues, which must be handled by a fairness enforcing protocol. Fairness is usually ensured over a time window of several network propagation delays. Thus, data flows might experience large access delays which might be not compatible to support time-sensitive applications. We solve this issue proposing the Multi-Fasnet protocol, which is able to enforce fairness in a relative short time scale, in the order of few propagation delays, without trading off the aggregated throughput network performance. We discuss Multi-Fasnet limitations and propose several novel strategies that achieve high and fair network throughput as well as low, bounded and fair access delay

    Comparison in power consumption of static and dynamic WDM networks

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    This is the author’s version of a work that was accepted for publication in Optical Switching and Networking. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Optical Switching and Networking, 8, 3 (2011) DOI: 10.1016/j.osn.2011.03.005Greening of the Internet has become one of the main challenges for the research community. Optical networks can provide an energy efficient solution, but it has become crucial to assess its power efficiency. In this context, dynamic operation of WDM networks is expected to provide significant power savings when compared to static operation; however, its benefits need to be evaluated to determine its actual impact and to analyze future trends. In this paper, a general framework for evaluating energy consumption in WDM networks is introduced. The proposed framework enables the analysis of different node architectures, link capacities and network topologies. In particular, the case of three different node architectures is discussed and compared. Results show that dynamic operation can significantly reduce power consumption when either the traffic load is below 0.4 or when short-reach transponders consume significantly lower power than long-reach ones. In the latter case, dynamic operation shows significant benefits compared to the static case for traffic loads higher than 0.4. It is also shown that the transponders of the input/output stage of the nodes determine the benefit–in terms of power consumption–of an eventual migration from static to dynamic architecture rather than the transponders of the interface between the WDM and higher layers.This work was supported by the UAM-Banco Santander CEAL grant, the “Juan de la Cierva” postdoctoral research grant from The Spanish Ministry Ministerio de Ciencia e Innovación (MICINN), DGIP-UTFSM Scientific Initiation Scholarship, Conicyt and DGIP-UTFSM Scholarships for PhD studies, USM Project 23.09.70 and Centro Científico Tecnológico Valparaíso Project #FB/28AB/10
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