A few fiber optic cable networking terms
Andrew Moore-Crispin • July 13, 2018if( has_post_thumbnail( $post_id ) ): ?>
Mystified by fiber optic cable terminology?
We try our best to avoid industry jargon. There are certain concepts, though, where jargon is the only concise way to say a thing. “Fiber blowing,” for example, beats “shoot air down a tube to reduce friction such that a fiber optic cable can be pushed as opposed to pulled through the conduit, lessening the risk of damage.”
We’ll continue to avoid jargon. That said, if your interest in the building out of a fiber network goes beyond “when will it be in my neighborhood?” there are a few terms and concepts it would be beneficial to understand.
The central office or CO is where the fiber switching smarts live and where all network traffic is sent to and received from the larger Internet and routed. If you’ve ever seen a server room, it looks a lot like that; thousands of wires and fiber strands coming into the structure and getting connected to high tech equipment, mounted in tall metal racks.
If you’ve never seen a server room, think about your home’s main electrical panel. A centralized unit routing power behind the walls, all over your house so that you can flip a switch and have light without even thinking about it.
Conduit is the rigid tubing that we place underground to house and protect the individual fiber strands that make up the network. Many smaller conduit tubes (called “micro ducts”) can live within a larger orange conduit. The configuration is determined by capacity needs.
Directional boring uses a steerable horizontal drill that creates a small, conveniently conduit-sized tunnel under obstacles like roads and utilities. Once the tunnel is in place, conduit can be pulled back through.
To ensure conduit can be located underground again, either by Ting, by the city or by a utility, a copper tracer line is placed along with the conduit. This line easily be found by any locate crew.
Locate / locates
There’s a lot of infrastructure underground. Water lines, sewer lines, gas lines, all kinds of stuff. We need to get an accurate map of what’s already there before we do any underground work at all. Finding and marking these utilities is called (appropriately enough) locating. We need to get these utility locates completed before we can do anything at all underground. Locates need to be done by the utilities themselves, by the city or by specialist companies. They can be a bottleneck in the process.
Where directional boring uses a horizontal drill over long distances, stitch boring uses an autonomous pneumatic missle. Stitch boring is an effective across short distances, which is how we use it. Where the directional bore can go under a wide road, a stitch bore is more suitable for going under a driveway.
A handhole is basically a small pit that’s dug to give access below ground. Directional boring and stitch boring both require a handhole be dug. Wherever possible, we dig handholes where a flower pot will be placed to minimize disruption.
Flower pot is an industry term for a buried access hatch. Many utilities use flower pots. They’re so common you may have ceased to notice them. A flower pot gives us access to the conduit that’s underground. A flower pot is where our network team makes the splices the individual fiber that runs up to a home or business to bring crazy fast fiber Internet.
Fiber is glass and so joining multiple strands together isn’t as simple as twisting them together like you would a copper wire. Instead, a specialized piece of equipment called a splicer is required. A splicer takes two pieces of fiber and fuses them together with a tiny and very nearly optically perfect laser weld.
The Splice Dome is where fiber technicians face off gladiator style to test their fiber splicing skills. Only one technician, the victor, emerges from the Splice Dome.
In network terms, a splice dome is where fiber branches out in multiple directions to allow for individual connections off the main trunk of fiber. Numerous splices are completed and the splice dome consolidates and protects these connections.
With conduit in the ground, the smaller fiber optic cables can be routed. Using a line fish and piece of highly specialized equipment called a “rope,” (in the industry parlance) these fiber cables are physically pulled into and through the existing underground conduit.
Fiber pulling is effective over short distances only. Attempting to pull fiber over long distances is difficult and can even put strain on the cables themselves.
Fiber blowing is a technique that allows fiber optic cable to be sent through the underground conduit while greatly reducing any risk of damage. Rather than being pulled, fiber is pushed. “Blowing” refers to air that is sent through the underground conduit to lessen friction. Wheels on the fiber blowing machine also help to push the fiber optic cable forward.
Using fiber blowing, fiber can be sent many hundred feet at a time without issue. Ting was the first company to popularize fiber blowing in North America.
Microtrenching uses a specialized machine to cut a small slot about 12 to 18 inches deep running parallel to the curb. The fiber, in its protective condtuit, is laid in the resulting slot. This process is relatively quick and much less disruptive to the surrounding area compared to traditional construction.