Design For Living: Fiber Optic Network Design

By Jim Hayes | Feb 15, 2017




Last month, I discussed the growing pains I have seen in fiber optics. Some of the problems have been issues with incompetent subcontractors, but poor network design seems to cause just as many issues. Why is that?

Fiber optic network design is a subset of a project. That venture may be a major building project or just the cabling being planned. But the project needs a manager who works with the team to create a scope of work that defines the goals of the entire project. Then the designer can start working.

Fiber optic network design is not simply sitting down with a CAD program and laying out cable routes for either outside plant (OSP) or premises cabling systems. It’s a lot more than knowing how to use software. The fiber optic network designer needs to have a broad knowledge of fiber optics and several other topics from communications systems to geology and codes.

A fiber optic network design begins with the communications requirements. Is the system an OSP link for a telecom or internet carrier, or is it a grid management system for an electrical utility? Is it cabling for a metro network for city communications, traffic management and security CCTV cameras? Maybe it’s premises cabling for a local area network or a mega data center. 

Every system is different and requires different design approaches. The designer must understand the needs of the network user and be able to translate that into a cable plant design.

Understanding the physical route of the network cabling is one of the most important parts of the design process. A site visit is absolutely necessary to understand the route the cable must take and the obstacles in its way. Outdoors, it means driving and walking the entire route, taking pictures along the way to document the physical environment the cable plant will take. A smartphone or a digital camera with geographic location recording is your best tool here.

Underground cables will require documenting where conduit and manholes already exist and where trenching is necessary. If there is any question about the soil conditions for trenching, a geologic survey may be necessary. Locations of poles and pole ownership need to be established if aerial cable is planned.

Access to poles is another thing to note. I’ve been working with a rural electrical co-op on an aerial fiber project, and finding locations for splice closures in the mountains and desert was only possible by following current electrical lines.

Choosing components is another important task for the fiber optic network designer. Correct choices will make the project easier and cheaper without compromising quality, but making those choices means having knowledge and experience with these kinds of components. The designer should get input from others beyond salesmen, such as experienced contractors that have worked with them before on successful projects. Contractors always have opinions on what works best based on their experience. Be wary of unfamiliar new products. Look for references to satisfied users and contractors before committing to something unknown.

Now is the time to start working on a project schedule. Usually the scope of work will include a timeline for finishing the project, but the designer needs to survey the site, design the route and have most of the actual cable plant design done before the schedule can be updated based on component deliveries and realistic installation times.

If the project goes out for bids, the design must be complete and the project scheduled for bids to be realistic. If it’s a design/build project, the designer will work closely with the contractor (or maybe for the contractor) to finalize details. If it’s open bids, the designer should be part of the group evaluating bids.

This is where things can get busy. Components need to be ordered. The proper construction equipment needs to be scheduled. Planning for storage of delivered components can be forgotten. The electrical co-op I have been working with found it needed to clear one of its storage buildings to make room for 60 miles of fiber optic cable, which came on 15 4-foot wooden reels!

Keep documentation up to date and do a final review before installation begins. Details such as the test plan—the requirements for testing and documenting the results—need to be completed. The final documentation should show where the cables run, photos at every splice location or other work site, where every fiber in every cable is connected and what were the final test results.

We’re about ready to begin installation, so the project responsibility falls on the project manager. I’ll cover that next month.

About The Author

HAYES is a VDV writer and educator and the president of the Fiber Optic Association. Find him at

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