NET NEWS: Mapping the Internet's Terra Nova

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Science  16 Oct 1998:
Vol. 282, Issue 5388, pp. 375
DOI: 10.1126/science.282.5388.375c

The information superhighway is nothing like a real highway in one key respect: It has no maps. If traffic gets snarled, it's impossible to find out where the congestion is or predict how traffic will change if, say, an arterial network is added. But researchers at the Cooperative Association for Internet Data Analysis (CAIDA) at the University of California, San Diego, have now unveiled the first large-scale views of the Net.

The maps, which can be seen at, are produced with a kind of cyber-radar called Skitter. Five source computers send out tiny packets of data programmed to travel a certain number of “hops” along the computers that route Internet traffic. The last router sends an error message back to the origin when the data expires, allowing Skitter to determine a packet's route. By sending out about 300,000 packets an hour to 20,000 preselected destinations, the scientists were able to produce maps such as this treelike picture depicting countries (the United States is blue, Germany red). Each branching point represents a hop.

Skitter's creators admit that the maps aren't very useful yet: “They're really messy and hard to interpret,” says Daniel McRobb, who wrote the program. But the group plans to add a third dimension that would make the maps easier to understand. They also plan to track how traffic patterns shift from minute to minute. Says project manager K. C. Claffy, “We're trying to get the tools to better understand this behavior.”

Despite their shortcomings, the new maps are “absolutely top-notch,” says Massachusetts Institute of Technology Internet researcher Carl Malamud. He has started a company, called Invisible Worlds Inc., that will sift through the terabytes of CAIDA data to produce interactive maps for members of the general public who might want to know, for example, where to mine financial info. “It's all about creating spaces that people can see,” says Malamud. “It's like the lights have been off on the information highway.”

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