A virtual time system for virtualization-based network emulations and simulations

Abstract

Simulation and emulation are commonly used to study the behaviour of communication networks, owing to the cost and complexity of exploring new ideas on actual networks. Emulations executing real code have high functional fidelity, but may not have high temporal fidelity because virtual machines usually use their host's clock. To enhance temporal fidelity, we designed a virtual time system for virtualization-based network emulations and simulations, such that virtual machines perceive time as if they were running concurrently in physical world. Our time virtualization is not exact: there exist temporal errors primarily due to scheduler timeslice, which is tunable in our system. We then study the tradeoff between temporal fidelity and execution speed under different lengths of timeslices, both experimentally and analytically. We demonstrate that our virtual time system is flexible such that it can achieve different level of temporal accuracy at the cost of different execution speed.

Keywords:

• network emulation
• virtual time
• virtual machines

Acknowledgements

This material is based upon worked supported under Dept. of Energy under Award Number DE-0E00000097, and under support from the Boeing Corporation. This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favouring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.