Optimality of a Network Monitoring Agent and Validation in a Real Probe

Abstract

The evolution of commodity hardware makes it possible to use this type of equipment to implement traffic monitoring systems. A preliminary empirical evaluation of a network traffic probe based on Linux indicates that the system performance has significant losses as the network rate increases. To assess this issue, we consider a model with two tandem queues and a moving server. In this system, we formulate a three-dimensional Markov Decision Process in continuous time. The goal of the proposed model is to determine the position of the server in each time slot so as to optimize the system performance which is measured in terms of throughput. We first formulate an equivalent discrete-time Markov Decision Process and we propose a numerical method to characterize the solution of our problem in a general setting. The solution we obtain in this problem has been tested for a wide range of scenarios and, in all the instances, we observe that the optimality is close to a threshold type policy. We also consider a real probe and we validate the good performance of threshold policies in real applications.