What Is the Difference Between Lit Fiber and Dark Fiber?

Lit vs. Dark Fiber: A Guide to Help You Decide Which is Best for Your Business

Leaving cable and dial-up in the dust, fiber-optic connectivity is the fastest and most reliable service available today. Traveling at nearly the speed of light, fiber connectivity transmits data at rates up to one hundred Gbps (gigabits per second). That’s equivalent to 100,000 megabits per second, which is significantly faster than cable Internet with download speeds ranging anywhere between 5 Mbps and 1 Gbps.

Offering more bandwidth and higher speeds over longer distances, businesses are taking note and making the switch to fiber at a rapid pace. In fact, the fiber-optic cable market size is estimated at nearly $13 billion in 2024 and is expected to reach more than $19 billion by 2029, according to Mordor Intelligence.

What Is the Difference Between Lit Fiber and Dark Fiber?

Deciding to go with fiber as your business’s connectivity solution is a great first step, but you have another choice to make. You have a choice between two fiber options: lit fiber and dark fiber.

So, what’s the difference between lit fiber and dark fiber? Simply put, lit fiber refers to fiber-optic cables that are currently in use, meaning they are “lit” by a service provider to transmit data. “Dark” fiber, on the other hand, refers to those fiber cables that aren’t in use.

Another common difference between lit and dark fiber is that lit fiber refers to fiber-optic infrastructure in which a service provider is utilizing to provide rate-limited services to an entity. Where-as a dark fiber product refers to leasing the physical fiber-optic infrastructure to an entity who can “light” the fiber themselves utilizing their own infrastructure.

Here, we take a closer look at the benefits and drawbacks of each to help you understand which option is best for your business.

A Closer Look at Lit Fiber

If you are looking for a convenient option for fiber-based connectivity, lit fiber is the way to go. From installation to operation and everything in between, the service provider manages the connectivity, giving you access to the high-speed and reliable service you need without having to worry about what’s going on behind the scenes.

• Convenience – Managed by service providers, lit fiber networks are ready for you to plug and play without much hassle or long ramp-up periods. Plus, the service provider takes on the liability of managing the connectivity for you, so you can focus on doing what you do best — running your business. And another good thing? Lit fiber networks tend to have broader coverage, including rural areas, as the Federal Government continues to invest in broadband expansion projects.
• Growing Capacity – Need a lot of bandwidth? No problem. Lit fiber capacities continue to grow, currently reaching to above 100 Gbps.
• Affordability – Unlike dark fiber (more on this later), your service provider handles the whole shebang for one monthly fee. From installation to maintenance and upgrades, managing your fiber connectivity is one thing you can keep off your to do list.

Deciding to go with lit fiber is almost like hitting the “easy button.” However, there are a few potential challenges to consider.

• Less Control – When utilizing lit fiber, the service provider delivers a specified and restricted amount of bandwidth capability, which can be limiting as your business grows. In addition, you will not have direct control over service/maintenance windows that are required to keep the network operating at optimal levels.
• Increased Cost for Additional Bandwidth – If you need to increase your network bandwidth in the future, the service provider may increase the rates associated with your service to adjust for the added capacity.

A Deeper Dive Into Dark Fiber

When you think about dark fiber, it’s like a blank slate. The fiber is exclusively yours, giving you full control to design and manage your network in a way that works best for your unique business needs. Dark fiber service provides virtually unlimited bandwidth and is highly secure. Let’s take a closer look at the advantages of dark fiber.

• Scalability – As your business grows and evolves, you may need to give your bandwidth a boost over time. The ultra-scalable bandwidth of dark fiber means that scaling up can require low effort with no concerns about running out of capacity since the speed is controlled by the electronics you choose to utilize.
• Reliability – As the sole user and manager of your network, you are in complete control. You don’t have to worry about relying on another provider to complete maintenance and upgrades. Instead of waiting on an external vendor, your own IT team can schedule service when it is most convenient for your business.
• More Affordable than Building Your Own Network – If you are certain dark fiber is the best option for your business, utilizing infrastructure that is already buried and ready for use is much more cost-effective than starting from scratch and installing new optic cables on your own.

Just like lit fiber, there are a few things to keep in mind with dark fiber.

• Management – While having complete control over your network can be a very good thing, it can also come with challenges. You are in charge of the network, so it’s important to make sure your business has the resources and IT expertise to operate your dark fiber efficiently.
• Cost – Having full control of your network also comes with some costs to consider. You’ll be responsible for the electronics fees associated to light the network and ongoing support required to keep it operating, and this can be costly to maintain and upgrade. Lastly, dark fiber is a commitment, it is often leased for longer periods of time.
• Availability – Currently used by K-12 schools, city and government entities, large corporations and enterprises for the most part, dark fiber is more prominent in populated urban areas.

To sum it up, both lit and dark fiber have a lot to offer — and no matter which option you choose, your business will benefit from higher speeds, more reliability and expanded bandwidth.

Want to learn more about Lit and Dark Fiber Services? Learn more about dark fiber and check out our network maps.