An emulation tool for PlanetLab

Network testbeds have become very popular to support research on network protocols and distributed applications. To reproduce network behaviour, testbeds range between two extremes: use a fully emulated network, or distribute nodes on the real Internet. The former approach yields very reproducible results but might be a poor representation of reality; the latter gives more realistic but less reproducible scenarios. In this paper we present an emulation solution for the PlanetLab testbed, and provide a detailed de-scription of its feature and performance. Our system gives researchers the advantages of emulation while not giving up the opportunity of running experiments in a large and heterogeneous testbed with realistic network conditions. The work is based on a Linux version of the Dummynet network emulator, extended with specific features to improve efficiency on PlanetLab, and with custom configuration mechanisms to simplify its use. The system described in this paper, developed as part of the Onelab2 project, has been deployed on a large subset of PlanetLab nodes. The emulation code itself is also available for ordinary Linux systems