What’s Dark Fiber?

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Dark fiber refers to unused fiber optic cable, which is abundant in the US due to oversupply in the late 1990s. Prices have fallen, making it practical for companies to buy and run their own networks. This has led to increased ownership by banks and colleges, as well as independent groups like Internet2 and National LambdaRail. The abundance of dark fiber provides unique opportunities for dedicated network capacity.

Dark fiber is a term used to describe fiber optic cable that is not used at the moment. The amount of unused fiber, particularly in the United States, is very high. This is in contrast to active fiber optic cable, often referred to as illuminated cable.

In the past, dark fiber was hardly ever sold. Telecommunications companies viewed it as their main asset, and selling it would be like selling your business. Due to a staggering glut in the market, however, cable selling has become extremely lucrative and is now a practice of many major telecommunications companies.

In the late 1990s, telecommunications companies created massive amounts of fiber optics. The economy of scale is particularly significant in the construction of fiber optic networks, where a large part of the cost is associated with the physical construction of the conduits, while the actual amount of cable is a minimal cost. Furthermore, the dot-com boom of the 1990s led many telecommunications companies to anticipate a future market much larger than what would actually exist, prompting them to build huge networks. Wavelength-Division Multiplexing (WDM) technology, developed in the mid-1980s and popularized in the late 1990s, dramatically increased the amount of data a fiber-optic cable could carry, further reducing the need for cabling.

The oversupply of dark fiber has driven prices down to levels where many companies that traditionally lease or lease live cable find it practical to buy unused cable in bulk and run it. Banks, in particular, which have huge traffic and infrastructure needs, are finding it increasingly convenient to own their own networks.

Even colleges are buying up dark fiber in never-before-seen numbers, building their own networks. Independent groups such as Internet2 and the National LambdaRail group are also buying it. In the case of the National LambdaRail group, the amount of dark fiber purchased is truly astounding, comprising over 9,000 miles of track (14,484km).
Prices at the peak of demand were around US$1,200 (USD) for a mile (1.6 km), but have since fallen dramatically, leaving no doubt as to what is causing the massive buying rush. With literally hundreds of thousands of miles of dark fiber having been laid down in the late 1990s, the market will likely be around for some time.
Many people look to this abundance to provide a unique opportunity for educational and research groups that might not otherwise be able to afford their own networks. Some envision a system in which universities are on independent networks, linked to each other and to the Internet. Others see great potential in connecting particle physicists directly from their research institutions to massive reactors like the Stanford Linear Accelerator Center (SLAC) or the Large Hadron Collider (LHC) at CERN.
However much dark fiber is used in the future, it is undeniable that the staggering amounts of unused cable provide a number of exciting possibilities in terms of dedicated network capacity.




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