A Black-box Router Profiler

Simulation, emulation, and wide-area testbeds exhibit different strengths and weaknesses with respect to fidelity, scalability, and manageability. Fidelity is a key concern since simulation or emulation inaccuracies can lead to a dramatic and qualitative impact on the results. For example, high-bandwidth denial of service attack floods of the same rates have very different impact on the different platforms, even if the experimental scenario is supposedly identical. This is because many popular simulation and emulation environments fail to account for realistic commercial router behaviors, and incorrect results have been reported based on experiments conducted in these environments. In this paper, we describe the architecture of a black-box router profiling tool which integrates the popular ns-2 simulator with the Click modular router and a modified network driver. We use this profiler to collect measurements on a Cisco router. Our preliminary results demonstrate that routers and other forwarding devices cannot be modeled as simple output port queues, even if correct rate limits are observed. We discuss our future work plans for using our data to create high-fidelity network simulation/emulation models that are not computationally prohibitive.