Traffic measurements are made to assess the delay and loss through a packet network, and to find the load and throughput of network elements. This is done by having several measurement points and observing and possibly time stamping packets as they pass by. The time stamping is done by using GPS synchronized clocks providing accuracy better than 100 ns (where GPS is the Global Positioning System). Comparing measurements from different points in the network enables the time delay and possible loss of packets to be found. These measurements are passive measurements and are done at high speed without any disturbance of the traffic. Another type of measurements are active or intrusive measurements. Here probe packets are injected into the network. These packets will inevitably load the network and disturb the traffic. The measurements form the basis for characterizing the traffic offered to the network and for making models. Traffic from video and audio sources is of particular interest. The metrics used here are different from those used to characterize the perceived QoS of audio and video.

Project coordinator: Professor Yuming Jiang and Professor Peder J. Emstad