Virtual Time Machine for Reproducible Network Emulation

Abstract

Reproducing network emulation experiments on diverse physical platforms with varying computation and communication resources is non-trivial. Many state-of-the-art network emulation testbeds do not guarantee timing fidelity. Consequently, results obtained from these testbeds can be misleading, especially when insufficient physical resources are provided to run the experiments. Reproducibility is far from being the norm. In this paper, we present a novel approach that can guarantee reproducible results for network emulation. Our system, called the Virtual Time Machine (VTM), takes advantage of both time dilation and carefully controlled scheduling of the virtual machines. Time dilation allows sufficiently scaled resources to run the experiments in virtual time, and controlled VM scheduling prescribes the precise timing of message passing for distributed applications---independent of the resource provisioning of the underlying physical testbed. Preliminary experiments show that VTM can guarantee reproducible results with varying time dilation, resource subscription, and VM scheduling scenarios.