Updated October 2026 · For IT leaders and larger businesses
Dark fiber and dedicated internet access both use fiber optic cable, but they are very different services. Dark fiber is unused fiber you lease and light yourself; dedicated internet access is a fully managed connection to the internet with guaranteed bandwidth.
Here is how they compare and which makes sense for your organization.
- Dark fiber gives full control but requires your own equipment and expertise.
- Dedicated internet access is managed by the provider with an SLA.
- Dark fiber suits large organizations linking their own sites.
- Most businesses are better served by dedicated internet or fixed wireless.
What Is Dark Fiber?
Dark fiber is fiber optic cable that has been installed but is not lit by a provider. You lease the strands and connect your own equipment at each end, deciding how fast to run them and what to send over them. It is commonly used to link a company’s own buildings or data centers.
What Is Dedicated Internet Access?
Dedicated internet access (DIA) is a connection to the internet with bandwidth reserved for your business, symmetrical speeds and a service level agreement. The provider manages the network and equipment. Cronus provides DIA over dedicated fiber and fixed wireless internet in Detroit.
Side-by-Side
| Dark fiber | Dedicated internet | |
|---|---|---|
| Who lights it | You | The provider |
| Internet included | No, separate | Yes |
| Equipment | Yours | Provider’s |
| Expertise needed | High | Low |
| Best for | Linking your own sites | Connecting a business to the internet |
Cost Considerations
Dark fiber can look inexpensive per strand, but it often requires long leases, construction to reach your buildings, optical equipment at each end, separate internet service and staff to manage it. Dedicated internet bundles all of that into one monthly service. For most businesses, the total cost of dedicated internet is lower.
Alternatives to Consider
- Private wireless links between your own buildings without leasing fiber.
- Virtual private networks or SD-WAN to connect sites over the internet securely.
- Fixed wireless DIA where fiber construction is slow or costly.
Questions to Ask Before Leasing Dark Fiber
- Where exactly does the fiber run, and how far is it from each building?
- Who pays for construction and building entry?
- How long is the lease, and what happens at renewal?
- Who repairs the fiber if it is cut, and how fast?
- Who will manage the optical equipment and monitoring?
Building Redundancy
Whether you choose dark fiber or dedicated internet, a single path is a single point of failure. Pair fiber with a diverse backup such as fixed wireless internet in Detroit or 5G SD-WAN so a construction accident does not take your sites offline.
Which Should You Choose?
Choose dark fiber if you have the expertise, need to link your own facilities and want full control. Choose dedicated internet access if you want a managed connection with guaranteed performance. Cronus can design either approach, including private wireless links between your buildings.
Frequently Asked Questions
What is the difference between dark fiber and lit fiber?
Dark fiber is unlit cable you light with your own equipment; lit fiber services are managed by the provider.
Is dark fiber faster than dedicated internet?
Dark fiber can carry very high speeds, but performance depends on your equipment. Dedicated internet guarantees a set bandwidth.
Does dark fiber include internet access?
No. Internet service must be purchased separately.
