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Three experimental environments traditionally support network and distributed systems research: network emulators, network simulators, and live networks. The continued use of multiple approaches highlights both the value and inadequacy of each. Netbed, a descendant of Emulab, provides an experimentation facility that integrates these approaches, allowing researchers to configure and access networks composed of emulated, simulated, and wide-area nodes and links. Netbed's primary goals are ease of use, control , and realism , achieved through consistent use of virtualization and abstraction.By providing operating system-like services, such as resource allocation and scheduling, and by virtualizing heterogeneous resources, Netbed acts as a virtual machine for network experimentation. This paper presents Netbed's overall design and implementation and demonstrates its ability to improve experimental automation and efficiency. These, in turn, lead to new methods of experimentation, including automated parameter-space studies within emulation and straightforward comparisons of simulated, emulated, and wide-area scenarios.

The success of ns highlights the importance of an infrastructure that enables efficient experimentation. Similarly, Netbed's automatic configuration and control of emulated and live network environments minimizes the effort spent configuring and running experiments. Learning from the evolution of these systems, in this paper we argue that a live wireless and mobile experimental facility focusing on ease of use and accessibility will not only greatly lower the barrier to research in these areas, but that the primary technical challenges can be overcome.The flexibility of Netbed's common abstractions for diverse node and link types has enabled its development from strictly an emulation platform to one that integrates simulation and live network experimentation. It can be further extended to incorporate wireless and mobile devices. To reduce the tedium of wireless and mobile experimentation, we propose automatically allocating and mapping a subset of a dense mesh of devices to match a specified network topology. To achieve low-overhead, coarse repeatability for mobile experiments, we outline how to leverage the predictability of passive couriers, such as PDA-equipped students and PC-equipped busses.

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