What is dark fiber?

Dark fiber is an optical cable that is installed underground but is not being used. Also called unlit fiber, dark fiber is an alternative to the subscription model of network services. It is leased by an owner, usually a telecommunication company, to the end user simply as cable infrastructure. Any service on dark fiber, including the switching equipment, routers and Optical Network Terminals (ONT), is the sole responsibility of the party leasing it. Operating a network segment over any length of dark fiber also carries the responsibility of complete system management.

What is dark fiber used for?

Dark fiber is used to prepare for high-capacity network service to meet future contingencies. The placement of underground utilities in an established area with preexisting infrastructure can be a disruptive process. Cables are often pre-positioned speculatively in anticipation of future use. This is especially true with planned business centers. In addition to enterprises in campus environments, organizations running their networks on dark fiber include schools, hospitals and government agencies.

How does dark fiber work?

Dark fiber allows organizations to use pre-installed cable to create, control and manage high-speed network capacity. Possible configurations include point-to-point or multipoint. Internet service providers (ISPs) and network service providers are not required. Compared to lit services, costs are fixed, and it delivers almost limitless network capacity. Bandwidth can be further increased by Dense Wavelength Division Multiplexing (DWDM) technology, which allows multiple channels to be carried by the same glass optical strand.

Lit fiber vs. dark fiber

While dark fiber and lit fiber are identical in a physical sense, they are very distinguishable in the parties responsible for their activation and use. Lit fiber networks are what we commonly associate with a network service provider when they own and maintain the fiber and equipment at both ends. Dark fiber networks are the do-it-yourself approach to enterprise networks, with a user leasing a segment of fiber optic infrastructure beneath its feet and providing their equipment to light the fiber at both ends.

What are the benefits of dark fiber?

• Scalability: Future-proofing is a significant benefit of dark fiber for businesses anticipating growth. Customization is entirely under the control of the end-user of a dark fiber system.
• Increased security: Industries that rely on the most sensitive data can be assured that any other entity does not share the segment being leased.
• Enhanced control: Leasing dark fiber allows businesses to gain independence from the ISP. You get to manage your network your way.
• Reduced network latency: Since the only traffic on a dark fiber system is that of the enterprise leasing it, there is no competition for bandwidth. Allocation of capacity can be managed directly to prioritize critical processes with low latency requirements.
• Reliability: Downtime is minimal with a dark fiber system. The underlying technology is inherently stable and made even more reliable with the exclusive use and simplicity a dark fiber lease brings.
• Lower cost: Operational costs are directly borne by the end-user instead of in a fee package with a service level agreement (SLA) from a network service provider. This makes costs predictable, and even during an unanticipated surge in traffic, costs will remain stable.

How to set up a dark fiber network

The process begins with creating network design requirements tailored to your enterprise. The dark fiber lease agreement is the next step. The provider approaches the end-user with a proposal to lease pre-installed cable between the users and internet access points. This is the standard dark fiber design—a point-to-point system. Design with a multipoint system approach is common in dense urban areas with a large and complex amount of existing dark fiber available. Transmission equipment needs to be selected based on the cable requirements, the current network requirements and the anticipated future needs of the organization. Once installed, several aspects of the network need to be configured and tested.

Lumen offers dark fiber internet location and leasing services for any size of the organization. Our high-bandwidth, low-latency connectivity is quick to configure, simple to lease and helps meet long-term business needs while controlling costs.

Lumen is a global leader in internet solutions, recognized for scalability, availability and reliability. Contact us today to explore fast, reliable Lumen^® Dark Fiber access.

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