Dark Fibre Network

A dark fibre network or simply dark network is a privately operated optical fibre network that is run directly by its operator over dark fibre leased or purchased from another supplier, rather than by purchasing bandwidth or leased line capacity. Dark fibre networks may be used for private networking, or as Internet access or Internet infrastructure networking.

Dark fibre networks may be point-to-point, point-to-multipoint, or use self-healing ring or mesh topologies.

Because there is no intermediate resale of capacity, dark fibre networks can operate using the latest optical protocols using wavelength division multiplexing to add capacity where needed, and to provide an upgrade path between technologies without removing the network from service.

For example, many dark fibre metropolitan area networks use cheap Gigabit Ethernet equipment over CWDM, rather than expensive SONET ring systems.

They offer very high price-performance for network users who require high performance, such as Google, which has dark network capacities for video and search data, or wish to operate their own network for security or other commercial reasons.

However, dark fibre networks are generally only available in high-population-density areas where fibre has already been laid, as the civil engineering costs of installing fibre to new locations is often prohibitive. For these reasons, dark fibre networks are typically run between data centers and other places with existing fibre infrastructure.