We introduce a novel passive network monitoring architecture which enables us to capture and integrate data from different levels of the protocol stack using a probe which can be placed at any arbitrary point in the network. We subject the data gathered to off-line analysis and show how, by modelling the dynamics of the protocols observed, we are able to extract information which would not be available using existing means. We show how the technique can be used to passively measure Web server response latency. Experiments are described which use artificially generated loads to validate the techniques used, and results obtained from the observation of real traffic are presented.

In the management of a modern LAN or campus network, two issues are of key importance, namely network performance and capacity planning. In this paper we report on results from an experimental programme which aims to quantify the performance that can be achieved with a real distributed application running over a range of different network technologies, including Ethernet, ATM, FDDI, and a 100 Mb/s packet-switched LAN. In particular we analyse the contribution of each of the various application and network components to the overall performance experienced by applications.

In the management of a modern LAN or campus network, two issues are of key importance, namely network performance and capacity planning. In this paper we report on results from an experimental programme which aims to quantify the performance that can be achieved with a real distributed application running over a range of different network technologies, including Ethernet, ATM, FDDI, and a 100 Mb/s packet-switched LAN. In particular we analyse the contribution of each of the various application and network components to the overall performance experienced by applications. This information will facilitate planning and management of new networks, and permit the identification of "hidden costs" which prevent currently deployed applications from fully exploiting high bandwidth networks.