Dark Fibre Explained

What is Dark Fibre? Simply put, its fibre optic cables (for a leased line, for example) that have been laid, but which aren’t transferring data. Its called dark because its not “lit up” so no light passes through, which is how the data is transmitted through fibre services like leased lines.

The reason unused fibre is laid is because most of the cost for providers comes from the physical installation. So, if they are already installing a fibre line for a customer it makes sense to put more than one in for future cost saving, instead of having to install a new line they would simply “light” the dark one up for the new customers.

To understand dark fibre its important to know the difference and when broken down its relatively easy comparing the two main fibre optic network options – Dark fibre & Active or lit fibre. The key difference is active fibre is usually sold by internet service providers & means the infrastructure provider will deliver the cable itself and the equipment at each end to make it work.

Dark Fibre, however, is rented just as the fibre cable itself and the company renting would then be responsible for putting the equipment on & creating/monitoring a network on the line. This kind of work is not for your every day business & would require specialist IT departments to deploy.

Dark Fibre products are usually only needed by data centres or backhaul technical operations & requires a high level of IT expertise and maintenance to work effectively. Most standard businesses would not need or want a dark fibre connection.

Dark Fibre Network Benefits

Despite the work involved setting up & maintaining a dark fibre network, there are some benefits that are particularly useful. These apply to everyone using it, but is particularly important to certain industries like data centre providers & wealth management/fintech companies.

1. Bandwidth Future proofing & scaling– Having dark fibre puts you in control of the bandwidth you need & can be scaled up accordingly. This is a relatively easy process and can effectively make your network almost limitless for its capacity. In the UK with everyone using more bandwidth having a private line can really help put your business one step ahead.
2. Route Diversity – Because you design your own network you can ensure it travels a route you require, eg. noit touching anyone elses network. You are also able to create a secondary diverse route which can also help with disaster recovery plans.
3. Security – The main reason companies install a dark fibre network is to manage their security. The dark fibre is physically laid to your location & at no point shared with anyone else or any other network. This makes the line more secure & helps certain industries prove regulatory compliance is being followed.

Why Do Dark Fibre Networks Exist?

Fibre leased lines are still a relatively new concept, which means that availability can be a concern for businesses. Businesses are able to have a leased line cable installed, but unless there is already an existing network, there can be some construction costs — and a fair amount of time — involved in the process.

With demand for leased lines increasing, we’re starting to be a little more proactive, and if a fibre optic cable needs to be laid, it is likely that a second cable with being laid simultaneously where possible, for use in the future. This minimises the work involved and can help to reduce costs, too.

This means there are already miles of dark fibre in the ground across the UK and allows dark fibre offers to be pretty competitive. However, for business owners thinking you could save money on a standard leased line its important to understand the cost of setting up a private network & maintaining it with a team of experts and not a decision that should be taken lightly.

What is dark fibre used for?

There are two possible uses for dark fibre networks. Firstly, internet service providers like BT and Virgin Media may look at purchasing these cables in the future to meet demand. Some providers may install dark fibre for this very reason, although its more likely they would want to build their own network & futureproof for that growth.

Secondly, businesses themselves may consider purchasing the cable for the operation of their own private leased line.Most businesses would already know if they needed and could maintain a dark fibre line, so if you don’t its likely you would be better on a internet leased line.

A Lucky Mistake

Interestingly, the dark fibre industry emerged quite by accident. Previously, companies would pay for more cables than was necessary for an attempt to future-proof themselves and protect against potential overcapacity. However, as the amount of data that was able to be carried by an optical fibre steadily increased over the years, these backups became largely obsolete.

It was this abundance of unused cables that sparked what is arguably one of the sector’s biggest and most promising advancements: dark fibre. IT experts and professionals were quick to move on them and find a use.

It is anticipated that access to dark fibre networks will soon become easier in the UK thanks to new Ofcom regulations which stipulate that BT must enable competitors to utilise their dormant cables. This would allow more internet service providers to offer affordable leased lines for their customers.