Dark fiber is fiber in the ground with no light on it. When you lease dark fiber you are leasing the physical strands between two points; you supply the transmission equipment at each end, so the capacity, protocol, and encryption are entirely your decisions rather than a provider's product tier.
The optics at both ends, the spares, the monitoring, and the fault isolation above the fiber layer. The provider remains responsible for the physical plant — locates, maintenance, and repair after a cut — but you will usually be the one who notices a problem, because you own the equipment that sees it.
Across a short metro span, dark fiber needs little more than a pair of matched optics. Over long distances it needs amplification and dispersion management, and beyond a certain reach, regeneration. That is why dark fiber economics look completely different for a campus link than for a hundred-mile regional route, and why the equipment estimate matters as much as the lease rate.
Dark fiber is normally sold as a multi-year lease or an IRU, priced against route distance, strand count, and term rather than against bandwidth — because bandwidth is not the provider's to sell you. The long horizon is intrinsic: the value of the arrangement is control over many years.
Dark fiber suits organizations that already operate network equipment and want the capacity ceiling and upgrade schedule under their own control — carriers, utilities, research and campus networks, and data-centre operators. For organizations without that capability it transfers work that a lit service absorbs, and the total cost of ownership usually favours lit service.
Dark Fiber is one of the specifications these comparisons turn on.
Describe the requirement and an engineer will tell you which service actually fits — without a rate card or a sales script in the way.
Service availability depends on location, network proximity, capacity, and engineering review. Share an address and we will confirm what can be delivered there.