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 COLUMN
Qwest is testing its lambda switching Net backbone with Corvis and Qtera THE LONG MARCH toward an all-optical Internet broke into a sprint last month with Qwest Communications' announcement of a year-2000 deployment of "lambda switching" in its backbone.
In physics, lambda denotes the length of waves, including light, sound, and Ethernet waves. Lambda appears in the fundamental wave equation, which holds that the velocity (v) of a wave is equal to its frequency (f) times its wavelength (lambda), or v=f*lambda. When talking about light or Ethernet waves, v is near the speed of light, which in a vacuum is a constant, c, of about 300 million meters per second. Fiber-optic transmissions usually have lambdas between 750 and 2,500 nanometers. These lambdas are "near infrared," invisibly just to the left of red, the left-most color in the visible spectrum. With c=f*lambda, the frequencies of optical transmissions are around 100,000 billion cycles per second, or 100 terahertz (THz). I laid all this out for our son, Max. Next thing I know, he prints a page from his room and races down the hall into my office, arriving just before my printer starts up -- "faster than the speed of light." Try explaining the speed of software to a 10-year-old. Anyway, recent advances have led to the multiplexing of many optical signals on a single fiber -- dense wave division multiplexing. It's a near-term industry goal to transmit 100 lambdas, each carrying 10Gbps, for a total per fiber of one terabit per second (1Tbps). Remember not to confuse terabits with terahertz. Qwest (www.qwest.com) just announced current testing and imminent deployment of lambda switching. By this they mean equipment that is able to receive, switch, and transmit optical signals without converting them into electrons for switching and back into photons for transmission -- equipment that switches photons instead of electrons. So imagine that Qwest's optical switches spread across the United States. Imagine them in a mesh of 18,500 miles of optical fibers, each carrying a bunch of lambdas. Imagine needing bandwidth between two cities. You connect to Qwest's network control center with a browser, you specify how many lambdas you need between which cities, and the switches reconfigure to deliver them a few milliseconds later. You can use your lambdas to carry whatever bits you want, although Qwest expects most of them will be Internet packets. Vab Goel, vice president of emerging technologies, says Qwest is testing optical networking products from Corvis (www.corvis.com) and Qtera (www.qtera.com), but not yet from Lucent Technologies (www.lucent.com). Visit the Web sites of these companies and find all claiming to be first in optical backbone networking, which is great. And these are of course not the only three. Competition continues to drive Internet backbone transmission and switching costs down. Small point, but I must object to what Lucent calls its marvelous new 256 x 256 optical cross-connect -- LambdaRouter. Sorry, but it does not do what any Internet engineer would call routing. It switches lambdas. It doesn't even know if the lambdas are carrying Internet Protocol. Foul! I recently got a chance to speak with Cherry Murray, research director at Lucent. She had a lot of interesting things to say, but what struck me the most is her estimate that optical fibers are these days being deployed at Mach 3. Mach 1 is the speed of sound -- 1,125 kilometers per hour at sea level. Even if you assume there's more than one truck involved, Mach 3, or 1,974 miles per hour, is a lot of fiber going into the ground. Hurray! So it would seem, if the copper monopolies can be shoved aside, a rainbow of lambdas will be switching into your home pretty soon, maybe even in my lifetime. Tune in next week for another letter of the week: the at sign (@). It isn't Greek, but ASCII. And you see it a lot in e-mail addresses. Technology pundit Bob Metcalfe hopes you appreciate the extension he arranged on the bursting of the Internet stock bubble. But if you've not sold yet, you're on your own, and no complaints at metcalfe@idg.net.  RELATED SUBJECTS  Network HardwareMORE > SPONSORED WHITE PAPERS 
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