On the schedulability of measurement conflict in overlay networks

Abstract

Network monitoring is essential to the correct and efficient operation of overlay networks, and active measurement is a key design problem in network monitoring. Unfortunately, almost all active probing algorithms ignore the measurement conflict problem: Active measurements conflict with each other - due to the nature of these measurements, the associated overhead, and the network topology - which results in reporting incorrect results. In this paper, we consider the problem of scheduling periodic QoS measurement tasks in overlay networks. We first show that this problem is NP-complete, and then propose a conflictaware scheduling algorithm whose goal is to maximize the number of measurement tasks that can run concurrently, based on a well known approximation algorithm. Simulation results show that our algorithm achieves 25% better schedulability over the existing algorithm. Finally, we discuss various practical considerations, and identify several interesting research problems in this context. © IFIP International Federation for Information Processing 2007.