A dark fibre or unlit fibre is an unused optical fibre, available for use in fibre-optic communication. Dark fibre may be leased from a network service provider. Dark fibre originally referred to the potential network capacity of telecommunication infrastructure. Because the marginal cost of installing additional fibre optic cables is very low once a trench has been dug or conduit laid, a great excess of fibre. MotivationsMuch of the cost of installing cables is in the work required. This includes planning and routing, obtaining permissions, creating ducts and channels for the cables, and finally installation and connection. For many years would not sell dark fibre to end users, because they believed selling access to this core asset would cannibalize their other, more lucrative services. Incumbent. Dark fibre can be used to create a privately operated network that is run directly by its operator over dark fibre leased or purchased from another supplier. This is opposed to purchasing or capacity.
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