ToMaTo - a network experimentation tool Dennis Schwerdel 1 , David Hock 2 , Daniel Günther 1 , Bernd Reuther 1 , Paul Müller 1 and Phuoc Tran-Gia 2 1 Integrated Communication Systems Lab, University of Kaiserslautern, Germany {schwerdel,guenther,reuther,pmueller}@informatik.uni-kl.de 2 University of Würzburg, Germany {david.hock,trangia}@informatik.uni-wuerzburg.de Abstract. Networks are an important field of research in information technology and experimental facilities are key instruments to enable prac- tical research in this area. In the context of the German-Lab project, the topology management tool “ToMaTo” has been developed to be used as experimental facility software. This paper describes the features and the design of ToMaTo and evaluates it by identifying common experiment types and matching their requirements to the properties of ToMaTo. 1 Introduction The Internet has a large economic influence but is based on legacy mechanisms and algorithms from the 70’s and 80’s. The rapid evolution of applications and transport technologies demands for changes even of core technologies of the Internet. A lot of research work has been done on improving isolated aspects of the Internet but in the last years also a lot of holistic research efforts investigate concepts and technologies for future networks in general[7]. All of these research projects need ways to evaluate their ideas and results. In the beginning of the projects, theoretical models and simulations might be sufficient but at some stage a more realistic environment is needed. Real net- works and real hardware show unforeseen effects that cannot be modeled. New protocols and architectures will have to work with legacy components, i.e. cur- rently widespread hardware and software, which have often unpublished behavior details. Experimental facilities aim to provide a realistic environment for experiments using emulation techniques. In experimental facilities, there is always a trade- off between realism, concurrency and repeatability. Realistic environments show unforeseen and random effects that cannot be repeated. To be able to run concur- rent experiments on the facility, the access of each experiment must be restricted to sharable or virtualized resources which in turn limits the realism. A lot of software for experimental facilities has been developed and each one works at a certain level of realism, concurrency and repeatability. The German- Lab experimental facility allows its researchers to choose from various experimen- tal facility software. An experimental facility software called Topology Manage- ment Tool (ToMaTo) has been developed in the German-Lab project. ToMaTo