<P> The availability of wavelength - division multiplexing further reduced the demand for fibre by increasing the capacity that could be placed on a single fibre by a factor of as much as 100 . As a result, the wholesale price of data traffic collapsed . A number of these companies filed for bankruptcy protection as a result . Global Crossing and Worldcom are two high - profile examples in the US . According to Gerry Butters, the former head of Lucent's Optical Networking Group at Bell Labs, the amount of data that could be carried by an optical fibre was doubling every nine months at the time . This progress in the ability to carry data over fiber reduced the need for more fibres . </P> <P> Just as with the Railway Mania, the misfortune of one market sector became the good fortune of another, and this overcapacity created a new telecommunications market sector . </P> <P> For many years incumbent local exchange carriers would not sell dark fibre to end users, because they believed selling access to this core asset would cannibalise their other, more lucrative services . Incumbent carriers in the US were required to sell dark fibre to competitive local exchange carriers as Unbundled Network Elements (UNE), but they have successfully lobbied to reduce these provisions for existing fibre, and eliminated it completely for new fibre placed for fibre to the premises (FTTP) deployments . </P> <P> Competitive local carriers were not required to sell dark fibre, and many do not, although fibre swaps between competitive carriers are quite common . This increases the reach of their networks in places where their competitor has a presence, in exchange for provision of fibre capacity on places where that competitor has no presence . This is a practice known in the industry as "coopetition". </P>

What is the difference between dark fiber and lit fiber