Virtualization techniques in network emulation systems

The continuous increase of computational power has made viable the implementation of more and more sophisticated virtualization techniques. The use of virtualization in cluster environments to build on-demand computing infrastructures is a recent trend with a great potential. Cluster-based network emulators are a specific class of cluster-based systems whose main purpose is to help researchers evaluate the effectiveness of new protocols and applications in realistic, synthetically generated network scenarios. Both large scale experimental testbeds (such as PlanetLab) and cluster-based network emulation systems (such as Emulab) use virtualization techniques at the basis of their resource management mechanisms to achieve isolation and concurrent experiments execution. In this paper, we compare different virtualization techniques already adopted in this kind of distributed systems and illustrate the peculiar virtualization requirements of a cluster-based network emulator. Furthermore, we show how Xen can be used to build a flexible and scalable network emulation system.