At A Glance – Dark Fibre

Dormant sections of fibre optic cable networks with big business implications

Dark fibre refers to parts of optical fibre infrastructure – such as cables, switches and repeaters – that are not currently in use. The term arises due to the fact that light is used to transport data through fibre optic networks. When data is not moved across certain parts of the infrastructure, the area remains dormant, no light passes through it, and the section can therefore be thought of as ‘dark’.

Dark fibre is a typical feature of most fibre optic networks – the backbone of our internet infrastructure. When telecommunications companies lay cabling into the ground, they traditionally put in more than is currently required for present day data transfer. This tactic is designed to future proof network infrastructures from the growing amounts of data that need to be transported: it’s much more cost effective to lay down more cable than is needed at the first instance than to repeatedly dig up the ground…

When combined with advances in the way that data is packaged, leading to more efficient data transfer, this extra cable means that there’s a lot of dormant network capacity under our feet. Network providers are taking advantage of this opportunity by leasing dark fibre to individual companies. This offers benefits in the form of added income to the network provider, as well as a bespoke, private and superfast connection for the company in question. Dark fibre is particularly valuable to companies who want full control over their networks, as it enables them to cut out the middleman of the telecoms provider. It can also be cheaper than paying internet providers to use their networks.

The upcoming age of 5G has further implications for dark fibre. Fibre optic infrastructure will remain crucial to the provision of the UK’s 5G network, however there are doubts that existing cable capacity will be enough to support the much greater volumes of data required. Telecoms companies such as O2, Vodafone and Three have therefore appealed to Ofcom – the communications regulator – for dark fibre access.

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