Abstract
Simulation, emulation, and wide-area testbeds exhibit differ-
ent strengths and weaknesses with respect to fidelity, scalability, and man-
ageability. Fidelity is a key concern since simulation or emulation inaccura-
cies can lead to a dramatic and qualitative impact on the results. For exam-
ple, 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 profil-
ing tool which integrates the popular ns-2 simulator with the Click mod-
ular 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 fu-
ture work plans for using our data to create high-fidelity networksimula-tion/emulation models that are not computationally prohibitive.
