G.: Virtualization Techniques in Network Emulation Systems

The continuous increase of computational power has made viable the implementation of more and more sophisti-cated virtualization techniques. The use of virtualization in cluster environments to build on-demand computing infras-tructures 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 applica-tions in realistic, synthetically generated network scenar-ios. Both large scale experimental testbeds (such as Planet-Lab) 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 com-pare different virtualization techniques already adopted in this kind of distributed systems and illustrate the peculiar virtualization requirements of a cluster-based network em-ulator. Furthermore, we show how Xen can be used to build a flexible and scalable network emulation system. 1