Dark Fiber — What Is It?

Dark fiber is optical fiber infrastructure that is in place but is not presently being utilized.  In the simplest terms, it is another name for optical glass fibers that have been installed, either underground or on poles, but do not have any electronics or lasers attached. As these installations are unused, they are described as "dark".

Dark fiber was once used exclusively by large telecommunications carriers who leased the fiber(s) and "lit" multiple circuits over a single path.  The benefit to carriers was that they could buy or lease strands of fiber and utilize their own electronics and turn up as much bandwidth, or as many customer circuits as they wanted� without the need to upgrade their networks every time a customer needed more bandwidth or wanted to add another circuit.

Today the cost of dark fiber and the associated electronics required to light dark fiber have become very affordable and easy to use. In fact, optical gear has become so easy to install and use, it has been compared to installing and managing a T1 router. Large and even medium sized corporations can utilize dark fiber and enjoy the same benefits and cost savings as the carriers.

Corporations are utilizing dark fiber to increase the capacity and flexibility of their WANs, or to connect to the telecommunications service provider(s) of their choosing. With customer provided dark fiber connecting to the carrier POPs, the customer can increase bandwidth, turn up additional circuits or even change service providers with a moment's notice.

And lastly, because dark fiber is just the medium on which the waves of light travel, it is technology neutral.  Any application and any protocol can be transmitted over it, so the investment is protected long into the future.