A couple weeks ago, The Wall Street Journal published an article with the headline "Why the Glut in Fiber Lines Remains Huge." One of the statistics cited in the story is that 85% of available fiber optic lines are currently unused. Since that is true it seems that no one would be able to give new optical fiber away these days. Why, then, did Corning (NYSE:GLW) recently report a strong quarter, partly because of fiber sales that were up by more than 50% over a year ago? Verizon (NYSE:VZ) was one of its big customers.

Well, you probably won't be surprised that the picture is more complicated than the Journal's headline suggests. The fiber glut is primarily limited to long-haul routes that connect different cities and even different countries. Lots of fiber was laid on these routes during the '90s boom. After all, since the cost of installing a single fiber isn't much less than the cost of installing 100 fibers you might as well place enough that you won't run out soon. As a result, most of this fiber is sitting there unused, or "dark," as The Wall Street Journal article reported.

As you might guess, Verizon is not buying fiber to install on long-haul routes. Instead, it and some competitors are trying to eliminate the biggest bottleneck in the network; the connection of your home to the Internet. While some are skeptical about how long this can continue, Verizon has big plans to run optical fiber to the front doors of its customers (fiber-to-the-premises, or FTTP), which will enable the delivery of the "triple play": high-speed Internet, voice over Internet protocol (VoIP), and video services.

While the Journal article didn't mention FTTP, it did present a couple reasons for telecom equipment stockowners to be hopeful, despite the gloomy headline. For example, Internet traffic has grown at an impressive rate, even through the downturn. Andrew Odlyzko, a University of Minnesota professor and former AT&TCorp. (NYSE:T) researcher, estimates that Internet traffic has grown by 75% per year over the last 10 years. Here is how to better appreciate the magnitude of this growth rate. If you were able to achieve a 75% return in your investments over 10 years, $1,000 would grow to more than $269,000!

Also, James Crowe, CEO of Level 3 Communications (NASDAQ:LVLT), was attributed as saying that he expects the overcapacity of "lit," or active, fiber to be absorbed in less than a couple years. Putting unused fiber to use will require the purchase of equipment to transmit, receive, and amplify optical signals.

Growth in Internet traffic is likely to continue even if it grows more slowly than 75% annually. Continued penetration of FTTP in the U.S. as well as growth in Asia and elsewhere should ensure that traffic keeps increasing. While I don't expect a boom there is a chance now for network equipment manufacturers to grow after the huge contraction during the last four or five years. Growth coupled with much lower valuations may add up to good returns in the future.

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Fool contributor Dan Bloom doesn't own shares of any stock mentioned in this article, but he does own shares in several companies involved in networking.