Dark Fiber for Data Center Interconnect: A Complete Guide
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: 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: 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
What Is DCI? A Simple Guide to Data Center Interconnection
A growing company does not stay inside one building for long. Over time, it opens new offices in new places. Along the way, it gains more customers each year. As a result, it also saves more data each year. Eventually, the company ends up using more than one data center. Because of this, these data centers need a strong link. That link lets them work as one system. This is where DCI, or data center interconnection, comes in. DCI is a group of links and tools. Together, these links connect separate data centers. Once connected, the data centers share data safely. In turn, a company can move data between places fast, even when those places sit far apart. Meanwhile, more businesses move their work online. As they do, they save more and more data. Because of this, the need for a strong link between sites keeps growing. The part below explains this need. What is DCI? DCI stands for data center interconnection, which means the links that join two or more data centers. Through these links, the data centers share data smoothly. Fiber cables, switches, and other tools build these links. Together, the tools move large amounts of data from one place to another. Today, most companies run their systems across more than one site. They use multiple sites for backup, speed, and storage. As a result, a company can no longer skip this kind of link. Skipping it slows things down, loses data, and makes systems fall out of sync. Grand View Research found the world market for this technology was worth USD 10.12 billion in 2024. By 2030, the market will reach USD 20.37 billion. In other words, it grows at a rate of 13.1 percent each year. What are the main types of DCI? There are a few common types of DCI. Businesses pick a type based on their needs and budget. Some types focus on speed. Others, however, focus on low cost or more flexibility. The list below shows the main types. Building a stronger connection between your data centers DCI plays a big part in keeping modern businesses connected. More and more companies now use many data centers for storage, backup, and daily work. Even so, no two businesses move data the same way. The right setup depends on distance, budget, and speed. As data keeps building up every year, a clear plan for linking data centers becomes a basic part of running a strong network. Picking the right network partner matters just as much as picking the right technology. ARNet is a dark fiber provider that links data centers with its own fiber lines. Specifically, its network covers dark fiber, long haul fiber, metro fiber, and last mile fiber. Together, these fiber types connect data centers from site to site. Beyond that, ARNet works across Southeast Asia. It offers service in Malaysia, Indonesia, Singapore, and Thailand. As a result, ARNet helps growing businesses and large digital platforms move heavy data traffic. Check its dark fiber services here. See its full network coverage on this page. ARNet stands out for its wide fiber reach. Beyond that, it keeps a steady focus on network reliability. Its fiber lines carry heavy traffic without losing speed. This matters most when a business needs a constant link between its sites. Because the network reaches several countries in the region, companies get room to grow their connection over time. In addition, they do not need to start from scratch. Learn more on ARNet’s about page or its main site. About the Author Nabila Choirunnisa, Digital Marketing Executive at ARNet