Passive access capacity estimation for QoS measurement

The passive estimation of Internet access capacity is interesting both from a scientific perspective, because it requires the development of techniques and tools to extract such a capacity from a noisy set of traffic measurements; and from an industrial perspective, because it supports, in principle, the possibility to measure the Service Levels of IP Access Service offered by Internet Service Providers. This paper proposes models, techniques and tools aimed at passively estimating the maximum achievable downlink network-layer rate (capacity) of an access link to the Internet from inside a network. We propose a method that extends the well-known packet-dispersion approach to network capacity estimation by considering longer TCP packet sequences to minimize the impact of measurement noise and to obtain reliable estimation without the need of a large amount of data. The proposed approach has been validated on some small-scale experiments performed on residential ADSL lines under different interfering traffic conditions.