June 2001

Building a Better Backbone

Surging Internet growth has put pressure on telecom networks to keep up. Their most advanced R&D is going toward expanding the capacity of the long-haul cables that cross continent

By Neil Savage

On a giant screen at the Corning Museum of Glass in upstate New York, video images flash by-news footage of a war, an inauguration, a spaceshot, a game show-along with real-time projections of museumgoers staring up in wonder. The source of all these images? A strand of glass, thinner than a human hair, yet wide enough to carry more information than three million copper wires, the technology it replaced. Cor-ning is justified in showing off its invention: optical-fiber technology ranks as one of the technological miracles of the 20th century.

Too bad we're in constant need of new miracles to keep up with the voracious network demands that this century is placing on these thin glass fibers. Fiber optics is, after all, a pre-Web technology; and much of the fiber that carries-in addition to telephone conversations-today's e-mail messages, music downloads and video streams was installed before most people were even aware of those media. What used to seem like a shameless waste of capacity now seems woefully inadequate. Our appetite for bandwidth is growing at an exponential rate, with no sign of slowing. Tracey Vanik, technical director at telecommunications consulting firm RHK, compares the Internet to Star Trek's voracious Borg: "Whatever bandwidth is made available, the Internet will swallow."

Optical fiber made by Corning, Lucent Technologies and other giant telecom suppliers is found throughout the telecommunications system, connecting us when we browse our favorite Web sites or place calls to Tokyo. But much of the cutting-edge research being done today on fiber optics goes into improving the capacity of the system's "backbone": the fattest of the fat data pipes, which whip data across continents and connect urban centers.

"Backbone" is a convenient metaphor-but it gives too neat a picture. A vertebrate organism has a single backbone, but the telecom system doesn't; no single company owns these high-capacity interurban cables, and no one organization makes sure they are up to the challenge of meeting worldwide bandwidth demands. In some cases telecommunications companies-the WorldComs and Sprints and AT&Ts of the world-will seek to cover high-traffic routes with their own cables, laying spaghetti-like strands parallel to one another along highway and railroad rights-of-way, linking metropolitan loops across continents and oceans. In other cases, carriers lease optical-fiber cables from other carriers; indeed, some carriers are solely in the business of leasing backbone capacity.

All carriers, though, are faced with the same challenge: how to stay ahead of the bandwidth demand curve. Research at Corning and elsewhere shows that every improvement in performance comes at a price; building a better backbone seems to be a question of choosing just the right trade-offs.