Network traffic can become harder to manage as a company adds more applications, cloud services, storage, and data. When more data needs to move between different locations, an existing network may not have enough capacity. This can make expansion harder and increase network costs. A data center interconnect can help by connecting separate data centers through a dedicated fiber link.
The right network can make it easier to handle more data as needs grow. It can also give teams better control over their connections and help them plan for future needs. For this reason, it is useful to understand how data center interconnect work and how dark fiber can support it. The first step is to understand what dark fiber means.
What is dark fiber?
Dark fiber is unused fiber that has already been installed but is not carrying data. For a data center interconnect, a company can lease this fiber and use its own network equipment to send data through it.
The fiber provider takes care of the physical fiber route. The customer manages the equipment that sends data through the fiber. This gives the customer more control over the network and the capacity it uses.
This is different from a lit fiber service. With lit fiber, the provider activates the fiber and manages the connection for the customer. With dark fiber, the physical fiber and active network equipment are managed separately.
What is a data center interconnect?
A data center interconnect is a network connection that links two or more data centers. It allows them to exchange data, applications, storage, and other network services.
For example, a company may have one data center for its main systems and another for backup. The connection between them allows data to move from one site to the other. This can support backup, disaster recovery, cloud services, and other workloads.
Cisco also describes DCI solutions that connect data center equipment through high-speed optical links. This shows how fiber can provide the connection between separate data center locations.
With this basic idea in place, the next step is to see how dark fiber fits into the connection.
How dark fiber and DCI work together?
Dark fiber provides the physical path between two locations. Optical equipment then sends data through that path. In a data center interconnect, network equipment at each data center connects to optical equipment that sends signals across the fiber.
The equipment used for the data center interconnect depends on the distance and capacity needed. A short connection may use a simple optical link. A longer connection may use DWDM, which lets several signals travel through the same fiber pair.
Cisco’s DCI documentation shows that 400G optical connections can run over dark fiber. Its point-to-point design can cover up to 40 km without amplification and can reach much farther with the right equipment.
This means the fiber provides the path and the equipment controls how data moves across it. This separation gives organizations more choice when planning their network.
Benefits of using dark fiber for DCI
Dark fiber gives organizations more control over their data center interconnect network. It also gives them more room to grow as they need to move more data.
Here are some of the main benefits:
- More control: Customers can choose the equipment they want to use and manage it themselves.
- Easy to upgrade: When more capacity is needed, customers can upgrade their equipment instead of changing the fiber route.
- Dedicated fiber: The fiber is used for the customer’s own connection.
- Fits their needs: Customers can build the network based on how much data they need to move.
- Ready for the future: The same fiber route can be used with newer equipment as technology changes.
These benefits make dark fiber useful for organizations with growing data needs. Still, dark fiber is not the only data center interconnect option. The right choice depends on the organization’s network needs, budget, and future plans.
How much bandwidth does dark fiber DCI support?
Dark fiber does not have one fixed bandwidth limit. The capacity depends on the optical equipment, distance, fiber quality, and network design used for the connection.
Modern optical equipment can support 100G, 400G, 800G, and higher speeds for data center interconnect (DCI). Multiple wavelengths can also be used on the same fiber pair to increase the total capacity. The actual capacity depends on the equipment and network design used for the connection, according to Cisco and Nokia.
This means the same fiber route may support higher capacity later if the optical equipment used for the data center interconnect is upgraded. As a result, the physical fiber does not always need to be replaced when traffic increases.
Why does future data growth matter?
Data use continues to grow across digital networks. According to the Ericsson Mobility Report, global mobile network data traffic passed 220 exabytes per month in Q2 2026 and grew 23% from the same period a year earlier. This figure is for mobile traffic, not DCI traffic, but it shows how much data is moving across networks.
For a data center interconnect, this wider growth is a useful reason to plan for future capacity instead of focusing only on current traffic.
That is why capacity planning should be part of the network decision from the start. Planning ahead can make future upgrades easier and reduce the need for major network changes.
Key features to look for in a dark fiber DCI network
When choosing a data center interconnect fiber network, there are several important points to check:
- Route diversity: Check if different physical routes are available. A second route can provide another path if the main route has a problem.
- Fiber quality: Ask about fiber type, distance, and test results.
- Scalability: Check if the fiber can support higher speeds in the future.
- Data center reach: Make sure the provider can reach the data centers you need.
- Service support: Review repair times, maintenance plans, and service commitments.
- Network information: Ask for enough route information to support network planning.
- Coverage: Check if the provider can support other locations you may need later.
These points help teams look beyond the first connection. They also make it easier to compare different providers using the same requirements.
Deployment challenges to consider
Dark fiber can provide strong network control, but it needs careful planning. The fiber route is only one part of the solution. Organizations also need the right optical equipment, power, cooling, monitoring, and technical support.
Distance is another factor. Longer routes may need extra optical equipment or amplification. Fiber quality can also affect the distance and speed that the connection can support.
For a data center interconnect, teams should review the fiber route and optical design at the same time. A route may look suitable based on distance alone but may need extra equipment to reach the required capacity.
Good planning at this stage can help avoid changes later. It also makes the next step, choosing a provider, easier.
Choosing the right fiber infrastructure partner
The right data center interconnect solution should meet an organization’s current needs and support future growth. Important factors include how much data the fiber can carry, the number of available routes, network coverage, access to data centers, future expansion, and how much control the customer needs.
ARNet provides fiber network solutions for organizations that need to connect different locations. Its dark fiber solutions include metro fiber, long haul fiber, and last mile fiber. ARNet also has network coverage across Malaysia, Indonesia, Singapore, and Thailand. More information is available on the ARNet website, dark fiber solutions, and network coverage pages.
Organizations that handle more data, AI workloads, and growing digital needs need a fiber network that can support this growth. A reliable fiber route can provide stable connections between locations and support higher data needs over time. ARNet’s regional fiber network can help organizations build a strong connection between their locations while allowing room for future growth.
About the Author
Nabila Choirunnisa, Digital Marketing Executive at ARNet
