Adding emulation to planetlab nodes

Network testbeds have become very popular to support research on network protocols and distributed applications. When it comes to reproduce network behaviour, testbeds range between two extremes: use a fully emulated network, as in EmuLab, which yields very reproducible experiments but might be a poor representation of reality; or communicate through the real Internet, as in PlanetLab, resulting in more realistic but less reproducible scenarios. Having both features available in the same testbed, and being able to choose and mix the two at will, is clearly interesting for researchers. In this paper we present an extension of the PlanetLab testbed to add emulation capabilities to all nodes. The work is centered around the Dummynet emulator, which we ported to Linux as part of this project.