National Geographic : 2000 Jan
NATIONAL GEOGRAPHIC Mapping Cyberspace A bug amid a tangled orb, National Geographic's website is one of 88,000 endpoints in this sprawling map of the Internet created by Bill Cheswick and Hal Burch at Bell Laboratories. Mapping the Internet repre sents huge challenges. Wires and fiber-optic lines interconnect thousands of "routers," com puters that pass on electronic messages from source toward destination. This map shows only the most central routers: An endpoint above might represent a gateway to thousands of other machines. Most routers don't tout their presence or location. To find them, Cheswick sent out a bliz zard of electronic tracers, or packets, from his New Jersey computer. The messages were designed to "die" as they reached way points or destina tions. The machines at which the tracers perished sent back elec tronic death notices. Burch's program analyzed the notices to build the map, which the team jokingly calls a packet morgue. Burch and Cheswick's map shows only interconnectivity, but through painstaking detec tive work Tamara Munzner of Stanford University and her col leagues found the cities in which routers are physically located and created an interactive map that shows connectivity and geography (left). Why make such maps? "Maps help you think about things," says Munzner. Bill Cheswick agrees, adding that maps reveal patterns that generate questions for further research. TEXT BY ALLEN CARROLL ChiefCartographer JANUARY 2000 Colors represent different Internet service providers, organizations that maintain the "tin cans and string" of the Internet. For more maps visit www.national geographic.com.