January 18, 2018 | by Wayne Smith

Dark Fiber: Nebulous Fiber Network

We have noticed a lot of puzzled faces recently when a project being discussed is a “dark fiber” project. Throughout the years, Vertex Innovations has managed thousands of communications projects that could be categorized under this imprecise identification. Vertex is currently actively managing hundreds of projects that are being referred to as “dark fiber” projects. One would think that being so deeply involved with these projects would eliminate internal confusion about the definition of “dark fiber,” however it doesn’t. The reality is the seemingly technical term “dark fiber” encompasses many project variations associated with fiber optic networks. The listener must understand the context of the discussion to understand the specific “dark fiber” meaning being used.

An Evolving Definition

When fiber networks were first introduced to the communications industry, the term “dark fiber” specifically referred to an unused fiber network infrastructure. Within the network infrastructure the fiber was either lit-up or unlit (dark). It is called dark because it is not used or lit-up with light waves that carry data. This is clearly a technical definition. The definition of “dark fiber” generally extended to include all of the unused network equipment including the actual fiber optic cable, data switches and so on. Most installations of fiber optic cable include a portion of dark fiber since the actual fiber cable and equipment cost is minor in relation to the total installation cost of the network. It has been, and still is, financially beneficial to install additional, unlit network capacity for future growth.

You will note the original definition does not address the ownership and/or any business relationship to the fiber cable. Over time the definition of “dark fiber” has evolved to include the business relationship between the parties with interests in the end-to-end fiber optic infrastructure. This relationship usually consists of at least one party who owns the fiber, the lessor and one party who wants to lease its use, the lessee. It’s important to distinguish that this is not leasing shared capacity of an active fiber optic network where the network owner (lessor) operates the network for the lessee. Instead the lessee will be leasing the cable, related equipment and all of its capacity to operate it as part of its own privately-operated network. The lessee will assume all functions of managing the network. The lessor of the network can be a telecommunications carrier, a building owner or another third-party fiber network provider. The lessee can also be any one of these parties. As you can see, this definition depends on the business relationship between the interested parties.

The key is a “dark fiber” project can mean different things to different parties depending upon the context of the project. It can be a strictly technical definition, a business relationship definition or a combination of both.

Different Types of Dark Fiber Projects

Limiting oneself to the simple definitions of “dark fiber,” either unlit or leased from a third party, has the tendency to lead to confusion. It should be made more apparent that the term’s actual meaning is dependent upon the technical environment and business relationship being discussed. to really understand what type of “dark fiber” project is being discussed, it’s important to ask reasonable questions such as type of outcome intended for the project.

Vertex works almost exclusively on dark fiber projects where the fiber network is being leased from a third party and will be operated as a private network. Although seemingly similar in final use, the projects can vary considerably. Here are four different examples of dark fiber projects. It is common for Vertex to work on a project that is expanding the quantity of fiber cables that service a specific location like a cell site or building. These projects may require the replacement of existing conduit with larger conduit, needed to support more fiber cables, in addition to pulling new cable through the conduit. This project may be necessary for the operator to increase capacity or redundancy. A second example is a project where Vertex is managing the installation of new conduit and fiber to replace an older wire infrastructure that is currently servicing a cell site. Currently, there remain lots of cell sites not yet supported by fiber optic links. A third example is the installation of conduit and fiber in a new build cell site. Today virtually all new build cell sites utilize fiber optic links. Lastly is a project that requires activating third party fiber optic cable that links buildings to outside fiber networks. Linking buildings to the outdoor fiber cables opens up the possibility for providers to offer broadband services inside large buildings that currently may not be supported, except by competitors.

To recap, one should be aware that there are many different types of fiber projects that can be categorized as “dark fiber”. Our recommendation to always ask a few questions about the project to get a clear understanding about the actual tasks required by the project. And, because of our involvement in a variety of different types of projects, the experts at Vertex Innovations are able to manage nearly any type of dark fiber project. Just ask us how!