Dark Fiber and DWDM

Speculation of Google's national network owing to its buying of Dark Fiber and recent news about Google seeking vendors for DWDM implementations had raised my curiousity on what these terms mean.

Dark Fiber is essentially, optical fiber laid out by huge network companies in anticipation of a surging bandwidth demand during the 90s, but was never used or "lighted up". Hence the term, Dark Fiber.

Today optical fiber alongwith DWDM has become much cheaper and is hence eyed by enterprises to build their own networks. As this article from lightreading enlightens, now with optical fiber and DWDM technology becoming inexpensive, combined with the surge in anticipation of VoIP and IP-based applications, enterprises are seriously considering the option of their own networks.

For me, this explains a lot on the feasibility of Google's move. Stated below is an excerpt from the article which explains the contribution for the toning down of the cost of optical fiber. It now makes the picture clear to me.

Which brings us to fiber: It’s now substantially cheaper than it was in
1999. In the shadow of the bubble, huge global networks like Global Crossing Inc. (Nasdaq: GLBC - message board) and Group Telecom/360Networks went bankrupt. Through the process of reorganization, they were able to shed billions of dollars of debt and clean up their balance sheets. With that debt wiped clear, we were left with global fiber networks that now were available for pennies on the dollar.

For those curious about DWDM, here are some pointers:

1. A Webopedia definition
2. A tutorial from IEC
3. Detailed article on DWDM, applications and advantages from Cisco