Nov. 26, 2002 COLUMBUS, Ohio – A terrorist attack or other disaster that destroyed key telecommunications equipment in major cities would disrupt the Internet much like severe storms at airline hubs ties up the nation's air traffic, a new study suggests.
Researchers at Ohio State University conducted experiments in which they simulated what would happen if a disaster crippled major nodes of the Internet – places that house the equipment where Internet traffic is collected and distributed.
The results showed that major cities that serve as Internet nodes would continue to have network access in most scenarios, although it would probably be much less functional. But smaller and medium sized cities that link to the Internet through these major hub cities could be disconnected from the entire network.
"The Internet functions much like our air traffic system," said Tony Grubesic, who co-authored the study as a doctoral student in geography at Ohio State. "If weather stops or delays traffic in a major airport hub, like Chicago's O'Hare, air passengers throughout the country may feel the effects – even if they are not traveling to Chicago. The same is true of the Internet hubs. They can affect Internet traffic through much of the country."
Grubesic, who is now an assistant professor of geography at the University of Cincinnati, conducted the study with Morton O'Kelly, professor, and Alan Murray, an associate professor, both in geography at Ohio State.
Their results appear in the February 2003 issue of the journal Telematics and Informatics.
The Internet has become more vulnerable in recent years as it has become more commercialized, Grubesic said. The earliest predecessor to the commercial Internet of today was ARPANET, a computer network developed by the Department of Defense. It was designed specifically to withstand a nuclear attack by having a decentralized network, meaning there were many routes to and from each point on the network.
But that decentralized network is expensive to build and maintain, Grubesic said. As the Internet has become commercialized, the major network providers have moved toward a "hub-and-spoke" model that funnels Internet connections through major hub cities.
"If you would pick up an octopus, all of its tentacles would come up with it," O'Kelly said. "The major Internet nodes have tentacles that connect to many other cities. If you destroyed a major Internet hub, you would also destroy all the links that are connected to it. It would have ripple effects throughout the Internet."
The biggest impact would be felt in the small and medium-size cities whose only or main connections to the Internet come through the major hub cities. Larger cities often have multiple connections to the Internet in and out of the city and would be harder to completely disconnect from the Internet.
The actual impact of a network disruption would depend on a variety of factors, such as the cities affected by the disruption. Grubesic said the most severe impacts would occur if telecommunications equipment were destroyed in the six largest Internet hubs: Los Angeles, New York, Atlanta, Dallas, Chicago, and Washington, DC.
For example, Los Angeles is a major hub location connecting other large cities in the South and West. If Los Angeles were eliminated as a node on the Internet, many other cities in California may not have Internet access. But it would also hurt Internet accessibility in Las Vegas, Phoenix, Tucson, Denver, Dallas and Houston, the study suggests.
A relevant glimpse of what could happen with the loss of a major Internet hub occurred with the Sept. 11, 2001 terrorist attack in New York City, Grubesic said. One major telecommunication hub was located at Ground Zero, and the loss of that hub disconnected three New York counties from the state of New York's computer system. In addition, several major Internet services and e-business providers were left without service for nearly two days.
Grubesic noted that there are more than 40 network provider companies that make up the backbone of the Internet. Many of these companies have agreements to help distribute each other's Internet traffic, which would help if one company's equipment was destroyed in a disaster. Still, most of the companies have hubs in the same cities and a major disaster could destroy the infrastructure of multiple networks.
For that reason, Grubesic said networks should not be concentrated too much in major cities.
"The ability for networks to re-route, re-connect and have redundancy is clearly important for the survival of the Internet in the face of disasters," Grubesic said. "That's why a more decentralized Internet had advantages over a hub-and-spoke model."
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