Quality of service analysis of internet links with minimal information

Tesis doctoral inédita. Universidad Autónoma de Madrid, Escuela Politécnica Superior, julio de 201

On the real impact of path inflation in networks under production

Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. F. Mata, R. Gonzalez-Rey, J. L. García-Dorado, and J. Aracil, "On the real impact of Path Inflation in networks under production", in 8th International Wireless Communications and Mobile Computing Conference (IWCMC), 2012 , p. 53 - 58The research community has proved the existence and studied the root causes of Path Inflation on the Internet - end-to-end paths significantly longer than necessary. However, it has been typically ignored that the popularity of traffic destinations and, consequently, of network paths, is clearly heterogeneous - some destinations are popular while others are barely accessed. In this paper, we propose a trace-driven methodology to measure the Path Inflation accounting for the popularity of Internet destinations from a given network, thus evaluating the implications that Path Inflation exerts on real networks under production. This information is important for network operators because it allows them to objectively stand out those destinations whose connection analysis must be prioritized. The results of applying this methodology to the Spanish academic network show that the most critical regions to focus on are Spain's closest countries, which either are very popular or have large Path Inflation as a consequence of the use of transatlantic links as intermediate nodes, or both.The authors would like to thank the support of the Spanish Ministerio de Ciencia e Innovaci´on (MICINN) to this work, under project ANFORA (TEC2009-13385) and the FPU fellowship program that has funded this research wor

Factor analysis of Internet traffic destinations from similar source networks

This article is (©) Emerald Group Publishing and permission has been granted for this version to appear here (http://www.emeraldinsight.com/doi/full/10.1108/10662241211199951). Emerald does not grant permission for this article to be further copied/distributed or hosted elsewhere without the express permission from Emerald Group Publishing Limited.Purpose – This study aims to assess whether similar user populations in the Internet produce similar geographical traffic destination patterns on a per-country basis. Design/methodology/approach – We have collected a country-wide NetFlow trace, which encompasses the whole Spanish academic network, which comprises more than 350 institutions and one million users, during four months. Such trace comprises several similar campus networks in terms of population size and structure. To compare their behaviors, we propose a mixture model, which is primarily based on the Zipf-Mandelbrot power law to capture the heavy-tailed nature of the per-country traffic distribution. Then, factor analysis is performed to understand the relation between the response variable, number of bytes or packets per day, with dependent variables such as the source IP network, traffic direction, and country. Findings – Surprisingly, the results show that the geographical distribution is strongly dependent on the source IP network. Furthermore, even though there are thousands of users in a typical campus network, it turns out that the aggregation level which is required to observe a stable geographical pattern is even larger. Consequently, our results show a slow convergence rate to the domain of attraction of the model, specifically, we have found that at least 35 days worth of data are necessary to reach stability of the model’s estimated parameters. Practical implications – Based on these findings, conclusions drawn for one network cannot be directly extrapolated to different ones. Therefore, ISPs’ traffic measurement campaigns should include an extensive set of networks to cope with the space diversity, and also encompass a significant period of time due to the large transient time. Originality/value – Current state of the art includes some analysis of geographical patterns, but not comparisons between networks with similar populations. Such comparison can be useful for the design of Content Distribution Networks and the cost-optimization of peering agreements.This work has been partially funded by the Spanish Ministry of Education and Science under project ANFORA (TEC2009-13385), European Union CELTIC initiative program under project TRAMMS, European Union project OneLab, and the F.P.U. and F.P.I. Research Fellowship programs of Spain. The authors would also like to thank the anonymous reviewers who helped us to improve the quality of the paper

Traffic monitoring for assuring quality of advanced services in future internet

The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-642-21560-5_16Services based on packet switched networks are becoming dominant in telecommunication business and both operators and service providers must evolve in order to guarantee the required quality. Increasing bandwidth is no longer a viable solution because of the business erosion for network operators which cannot expect revenues due to the large investments required to satisfy new applications demand of bandwidth. This paper presents devices and a specific architecture of services monitoring platform that allows network operators and service providers to analyze the perceived quality of service and check their service level agreements. Thus, a cost-effective service management, based on direct IP traffic measuring, can be supported on integrated monitoring systems to provide network-centric mechanisms for differentiated quality of service, security and other advanced services.This work has been partially developed in the framework of the Celtic and EUREKA initiative IPNQSIS (IP Network Monitoring for Quality of Service Intelligent Support)

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Multiparametric magnetic resonance imaging-guided salvage radiotherapy in prostate cancer

Aim: To analyse the efficacy and toxicity of postprostatectomy SRT in patients with a BCR evaluated with mpMRI. Background: Multiparametric magnetic resonance imaging (mpMRI) has the ability to detect the site of pelvic recurrence in patients with biochemical recurrence (BCR) after radical prostatectomy (RP). However, we do not know the oncological outcomes of mpMRI-guided savage radiotherapy (SRT). Results: Local, lymph node, and pelvic bone recurrence was observed in 13, 4 and 2 patients, respectively. PSA levels were significantly lower in patients with negative mpMRI (0.4 ng/mL [0.4]) vs. positive mpMRI (2.2 ng/mL [4.1], p = 0.003). Median planning target volume doses in patients with visible vs. non-visible recurrences were 76 Gy vs. 70 Gy. Overall, mean follow-up was 41 months (6-81). Biochemical relapse-free survival (bRFS) at 3 years was 82.3% and 82.5%, respectively, for the negative and positive mpMRI groups (p = 0.800). Three-year rates of late grade ≥2 urinary and rectal toxicity were 14.8% and 1.9%, respectively; all but one patient recovered without sequelae. Conclusion: SRT to the macroscopic recurrence identified by mpMRI is a feasible and well-tolerated option. In this study, there were no differences in bRFS between MRI-positive and MRI-negative patients, indicating effective targeting of MRI-positive lesions.Sin financiaciónNo data JCR 20190.412 SJR (2019) Q3, 247/372 OncologyNo data IDR 2019UE