Lit Fiber vs. Dark Fiber: What’s the Difference?


Fiber optic cables are designed for high-performance data networking and telecommunications. When working with fiber optic cables, you may hear terms such as “lit fiber” and “dark fiber”. So what’s the difference between lit fiber and dark fiber? 

The Difference Between Lit Fiber and Dark Fiber

Lit fiber refers to fiber optic cables that are currently in use by a service provider to transmit data. On the other hand, dark fiber refers to fiber optic cables that are currently not in use. Even though the fiber optic cables in lit fiber networks have constant light pulses streaming through them and carry data, the cables in dark fiber networks don’t have any light pulses passing through them. 

Also, lit fiber refers to a fiber optic infrastructure that a service provider utilizes to provide rate-limited services to an entity.  In comparison, dark fiber refers to leasing the physical fiber optic infrastructure to a business that can light the fiber themselves by using their own infrastructure.

What is Lit Fiber? 

For businesses that need a convenient solution for fiber-based connectivity, lit fiber is ideal. Lit fiber networks are active, using light pulses to transmit data through fiber optic cables containing thin strands of glass. Furthermore, lit fiber carries data much faster compared to traditional copper cables that use slower electrical signals. 

In most scenarios, lit fiber networks are installed and operated by a service provider. Lit fiber enables businesses to provide data-intensive applications, cloud applications and other bandwidth connections with the speed required. From installation to operation, the service provider will manage the connectivity and provide access to the high-speed and reliable service. This means that you won’t have to worry about what’s going on behind the scenes. 

Benefits of Lit Fiber

Lit fiber provides a managed service so that you aren’t required to purchase, establish, maintain, or operate the equipment. By using lit fiber, it will reduce administrative costs and technical burdens for IT teams. The benefits of lit fiber include convenience, capacity, and costs. 

  1. Convenience – Lit fiber networks are managed by service providers, so you won’t have to deal with inconveniences or long ramp-up times. Since the service providers will take liability for managing the connectivity, you can focus on managing your business operations. 
  2. Bandwidth Capacity – Lit fiber provides a high bandwidth connection. If you need to increase your network bandwidth and avoid downtime, lit fiber capacities are always continuing to grow but can come with a cost if you need immediate changes. By determining if your bandwidth needs are well-defined, not likely to immediately change, or requires low bandwidth, a lit option is your key to cost savings.
  3. Costs – The responsibility for fiber network operations and maintenance is given to service providers Overall, lit fiber is a beneficial choice for businesses that don’t have specific security and ownership needs. By understanding and evaluating your business needs, it will help you save on administrative costs for your business.

What is Dark Fiber? 

If your business requires high-speed and high capacity, then dark fiber is ideal. Dark fiber optic cables are inactive, which have been laid underground and do not have service or traffic running on the fiber strands. It is typically used for telecom and network communications. Ultimately, dark fiber provides the maximum level of control and security for businesses, allowing you to use your preferred protocol and manage your own equipment.

Businesses can lease a dark fiber infrastructure and provide their own equipment to light the fiber. They will be able to deploy and operate the equipment required to “light” the fiber and use it for Internet access and communications. If your business has specific network requirements, then dark fiber is ideal for those that need control of their network infrastructure and require near zero response times for point to point communication.

Benefits of Dark Fiber

With a dark fiber network, the operator can act as their own ISP and avoid service delays that cause negative ISP to customer relationships. The benefits of dark fiber include scalability, network latency, security, and reliability. 

  1. Scalability: By investing in dark fiber, your business can increase its bandwidth capacity to upgrade the equipment powering the fiber. You’ll be able to access near unlimited bandwidth and won’t have to deal with additional monthly fees or service delays from the ISP.
  2. Network Latency: Low network latency is crucial  for businesses that depend on fast communication between different point to point communications portals or between large data centers that need to quickly communicate with each other. Dark fiber speed is controlled by the owner of the lease, so businesses using the technology don’t have to worry about sharing bandwidth with other customers. 
  3. Increased Security: Dark fiber networks are privately owned and operated by the lease owner, so outside entities can’t track or record the data and information being transmitted through the fiber. This is important for businesses and organizations that need to constantly transmit sensitive materials over a secure network.
  4. Reliability: With a dark fiber network, you have control of the system and can resolve the issue yourself instead of contacting ISP to send out a technician. You will also be able to minimize downtime if any problems occur, which is crucial for companies that want to lower costs. 
  5. Cost: Operators who use dark fiber networks can be reassured that the costs for running the network will be beneficial long-term. If your organization has a lot of data that needs to be moved around, it will save you more money to bring up your own dark fiber network rather than paying a large sum for an Internet provider. 

RackSolutions Server Racks, Cabinets, and Accessories

Fiber optic networks are constantly growing, so the demand is also increasing for high-performance data networking within data centers. You can read more about how to manage fiber optic cables in a server rack here

If you need an additional server rack or rack accessories to purchase for your network needs, feel free to contact us. RackSolutions provides a variety of server racks, colocation cabinets, hypershelves, and rack accessories that are ready to order. With our high-quality, in house manufacturing, you will be confident that you are buying the best rack possible for your data center! 

RS148 Data Center Server Cabinet


Lit Fiber vs. Dark Fiber: What's the Difference?
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Lit Fiber vs. Dark Fiber: What's the Difference?
Lit fiber provides a managed service so that you aren’t required to purchase, establish, maintain, or operate the equipment. With a dark fiber network, the operator can act as their own ISP and avoid service delays that cause negative ISP to customer relationships.
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Fiber Optic Cable Management