Researchers at Ohio State University simulated outages at 14 cities over 41 networks, and found that removing some of those cities from the Internet--because of terrorist attack, natural disaster, or some other reason--would result in significant disruptions of Internet traffic elsewhere in the country.
Los Angeles proved to be the most important city: Removing Los Angeles from the Internet resulted in significant disruptions of traffic to Las Vegas, Phoenix, Tucson, Denver, Dallas, and Houston. Removal of any of five other cities would also result in significant disruptions: Atlanta, Chicago, Dallas, New York, and Washington.
The network most susceptible to outages caused by the removal of a single city was AT&T; it was followed by GTE.
The study, to be published in the journal Telematics and Informatics in February, was written by researchers Tony Grubesic, Morton O'Kelly, and Alan Murray of Ohio State's Department of Geography.
The researchers attributed the vulnerabilities to the evolution from the distributed network topology of the early Internet to a hub-and-spoke topology.
"Although transmission speeds and capacities of today's commercial Internet clearly surpass those of its predecessors, the economics of network survivability and reliability have also become more relevant," the authors say. "With thousands of businesses, corporations, universities, and governments relying on the Internet for day-to-day functions, major disruptions in service have the potential to be economically catastrophic."