Measuring and analyzing service levels: a scalable passive approach” Quality of Service

Internet service providers are increasingly trying to differentiate themselves in terms of ser-vice performance that they provide to their users. To measure and quantify the service per-formance from end-users perspective, proper metrics and measurement methods are needed. Traditional measurement techniques are not sufficient for this purpose. In this paper, we have developed a scalable service level monitoring methodology to assess user satisfaction without injecting any measurement traffic. Specifically, we suggest web throughput as a service level metric, outline possible ways to measure it and discuss advan-tages of passive observations of actual user activity. We further propose a statistical data analysis method that analyzes passive throughput measurements, and quantifies user satis-faction/dissatisfaction and the confidence that the provider may have on the collected data, i.e. data reliability. The proposed technique is based on the premise that the service provider is interested in continuously monitoring the service levels being offered to a majority of the users over a long enough time. We present results of a real-world experiment that demon-strates that with careful data analysis, passive measurements are effective in detecting ser-vice problems. Our experiments also indicate that 90 % of the time, the results of reliabl