Multipoint measurement technique for bottleneck localization on E2E path

In a converged network environment, Internet protocol packets travel over a multitude of fixed and wireless networks before reaching the user application. If a user experiences poor quality of service, it is necessary to pin-point which part of the end-to-end path causes the degradation. In this work, a novel method and a measurement system prototype were developed to gather performance information from links and nodes in the network path. The heart of the system is a software called the Multipoint QoS measurement data Collector (MQC). It controls and collects network performance data (delay, throughput, jitter, packet loss) from commercial network protocol analyzer and QoS measurement tools located at the end nodes of the path. The system is able to perform one-way delay measurements, which provides a clear benefit over traditional round-trip time measurements. The laboratory measurements show that the accuracy of the GPS-synchronized system is in the order of tens of microseconds. That is, it is suitable for Ethernet and wireless network measurements. By performing measurements with the system over an HSDPA network, it was possible to localize a performance bottleneck in a UMTS radio access network. The measurements in a public Wi-Fi network showed that the system can also be used effectively in a public network environment. The system is in daily use at the VTT Converging Networks Laboratory and has shown technical and commercial benefits for customers. It will be developed further to improve the calculation of the QoS metrics and to enhance usability.