"One if by land, two if by sea" was Paul Revere's cipher, but after the Wright Brothers he would have to add "three if by air," and after Sputnik, "four if by outer space." Now a fifth threat has arisen: "five if by cyberspace." The threat of attacks on our global computer and communications networks has the U.S. Department of Defense moving its war games into cyberspace using emulations called software virtual networks. SVNs are already trickling down into the private sector too, enabling all sorts of commercial application developers—from Microsoft to NTT—to test their planned network rollouts before they are deployed.

"Cyber-warfare caused us to come up with the software virtual network definition and concept," said Steve Norry, director of engineering at Scalable Network Technologies (Los Angeles), during the recent MilCom 2009 conference (Oct. 19-21, Boston). "But lots of different kinds of companies are using software virtual networks now because it allows the nondestructive testing of everything in a network—from the applications all the way down to the physical devices."

For instance, Microsoft is using SVNs to test the Wi-Fi protocols in its mobile operating system. And NTT's DoCoMo—the main mobile phone operator in Japan—uses SVNs to emulate its base stations countrywide. Scalable Network Technologies' customer list now reads like a who's-who list of Fortune 500 companies, all using SVNs to emulate networks under real-world conditions.

"In the simulations that network designers use, the message always gets through to the recipient," said Norry. "But if you want to test whether interference or dropped packets or any number of real-world problems are going to adversely affect your network before you deploy it, then you need to use the real-time emulation of our software virtual network."

For the military, the software virtual network allows them to release their nastiest viruses, worms and other malware, then test them against their countermeasures. The military tests all sorts of real-world attack scenarios, such as network intrusions, wormholes, blind denial of service, simulated RF jamming and every other conceivable hack. SVNs allow cyber-warriors to stress-test applications for vulnerabilities, close security gaps and pinpoint routines that need to be rewritten.

"Cyber-warrior activities, whether it's malicious intent or countermeasures or defensive posture, can be an expensive proposition for a physical network as they hack away at it to see what can be destroyed and what can be preserved," said Norry. "So being able to create an emulation in synthetic space gives you a nondestructive infrastructure where you can do multiple iterations, multiple variations, and not have to consume a lot of time and dollars and hardware just to do those tests."

For commercial customers, instead of viruses and worms, it's tall buildings blocking reception, interference from nearby TV towers or a thousand other facts-on-the-ground about where and how a network will be deployed that need to be emulated.