Project Description

Broadly, our goal is to assess network link characteristics in order to develop methods for quality assurance against network failure and security from malicious attack. We focus on estimating link loss rates and delay distributions using end-to-end measurements made across several links. We do this by transmitting end-to-end probe packets from a sender node to collections of receiver nodes. For example, in the simple network shown here, we might send a number of probe packets from the sender <0> to each set in the collection of receiver pairs <4,5>, <5,6>, and <6,7>. Based on the measured end-to-end losses and delays of these packet probes, we can reconstruct the loss rates and delay distributions for each individual link in the network. Along these lines we have pursued several goals. We have established a necessary and sufficient identifiability condition for the collection of experiments. We have also developed fast estimation algorithms with a goal of real-time monitoring for intrusion and anomaly detection. There are several current and future directions we are pursuing. We have begun work on estimating and/or characterizing continuous distributions using moment estimating equations and quasi-likelihood techniques. Additionally, we have started to consider the situation in which the link characteristics vary with time. These improvements further enhance our ability to make accurate assessments of the network and thereby improve our ability to monitor it.