The basic philosophy of modern LAN wiring is the concept of structured cabling. The entire networking system is broken up into chunks that allow workstation wires to be concentrated.
In a typical enterprise LAN system, the fiber optic network consists of telecommunication rooms, backbone wiring, work areas and horizontal wiring.
Let's illustrate this with a 3 stories building.
On each floor, there will be a telecommunication room sitting on top of each other. These telecommunication rooms hold all network equipment such as routers, servers and switches. Telecommunication rooms are linked together with fiber optic cables passing through vertical shafts which are called backbone wiring/cabling or vertical wiring/cabling.
The backbone fiber optic cables typically run at 10Gbps Ethernet speed to provide enough bandwidth for the whole enterprise.
Work areas are work stations (PCs) divided into cubicles. These work areas are connected to each floor's telecommunication room with horizontal cabling. These horizontal copper/fiber optic cables typically run at 1Gbps Ethernet speed.
How to pull the fiber optic cable through vertical shaft
The backbone cabling used to be twisted pair copper cables. But now it is typically multimode fibers or even single mode fibers.
There are many tools available to pull the vertical backbone fiber cables. These include Gopher poles, cable caster pulling tools or fish tapes. And usually you need to install a pulling eye to protect the fiber cables and connectors while pulling the fiber cables.
How to terminate a backbone vertical fiber optic cable?
The backbone fiber optic cables come in without termination (connector). You usually need to terminate these fibers with fiber optic connectors such as ST, SC or LC connectors.
The termination steps are not extremely difficult but it does require some extensive training before you can do a fairly good job.
Fiber optic termination tools
The tools needed for fiber terminations are fiber optic cable strippers, Kevlar cutters, fiber cleavers, ST, SC, LC or MTRJ fiber optic connectors, fiber connector hand polishing puck, fiber polishing films and fiber inspection microscope.
Fiber optic cable termination steps
1. Strip the fiber
Fiber cables come with 3mm jacket, Kevlar strength member and 0.9mm buffer coating. To get to the 0.125mm fiber cladding, you need to remove the 3mm jacket with a fiber jacket stripper, then cut the Kevlar fibers with a Kevlar cutter, finally strip the 0.9mm buffer down to 0.125mm cladding with a fiber optic stripper.
2. Cleave the fiber
After stripping the fiber down to 0.125mm cladding, you insert the fiber into a SC, ST or LC connector, and then inject some fiber optic epoxy into the connector with a syringe.
You will then lay the connector into a hot oven to cure the fiber epoxy so it can hold the fiber tightly.
After the curing process, you cleave extra fibers from the connector tip with a fiber optic cleaver.
3. Hand polishing the fiber
In the next step, you put the connector (already with fiber fixed inside) into a hand polishing puck, which serves as a fixture while you polish the end face of the connector to get a high quality mirror like finish.
You then hold the polishing puck and polish the connector on a connector lapping film in a figure 8 shape for 10~15 times.
Repeat the hand polishing steps stepping from 12um, 3um and 0.5um lapping films.
4. Fiber termination quality inspection
The final step is to inspect the quality of your work. You insert the finished connector into a fiber optic inspection microscope which zooms to 200 to 400 time level to show you all the scratches and pits that may exist on the connector end face. If everything looks perfect, then you can connector your fiber into the network.
This only touches the surface of building a fiber optic network. We have tons of information on our web site. Follow the links below to discover even more!
Fiber Optic Network Design
Fiber optic cable termination can be divided into two major groups: factory termination and field termination.
Field technicians face important trade-offs in deciding which approach to choose. For tighter loss budget, the best approach is factory terminated cables since it is much easier to achieve loss loss and high quality connector terminations in a controlled factory environment. On the other hand, field terminations provide far more flexibility in meeting system requirements.
Pros of factory termination
1. The factory has to guarantee the quality. Fiber optic manufacturers have highly trained technicians and high quality equipment for the job. Factory technicians usually are expert on fiber connector polishing and they produce thousands of fiber optic patch cords and fiber pigtails on a daily basis.
2. Factory termination provides the lowest cost. Since factories produce mass quantity of fiber patch cords, they have reduced the cost to the lowest possible point. This is the most economic choice.
Cons of factory termination
Factory termination doesn't provide as much flexibility as field termination. You have to write down the list of fiber lengths and quantities and you have to make sure that you have enough spare length of cable for each termination.
Pros of field termination
1. Field termination provides the best flexibility in meeting system requirements. You can just pull the fiber cables and terminate them later.
2. You can do on-the-spot repairs wherever there is a defective fiber link. This is the biggest advantage of doing the termination yourself.
Cons of field termination
1. High cost. You need some polishing tools and supplies. Field termination quality are OK for multimode applications, but for single mode applications, you'd better leave that to factory termination.
2. The field termination technician must be highly skilled. He would have to practice a lot offline before doing the real work. A bad termination can cost you both time and money.
OK. You must already have a pretty clear idea on the choices for fiber cable installation now. Let's examine in more details on the available options for each category.
Factory termination choices:
1. Factory pre-terminated cables
For this type of job, you provide a list of cable types, lengths and quantities to the factory. The factory will deliver each pre-terminated cable on a reel. You just need to pull these cables through duct carefully with a cable netting to protect the connectors.
2. Factory pre-terminated pigtails and splicing (fusion splicing or mechanical splicing)
This is a intermediate approach. You order cable segments with factory-mounted connectors on one end only. You need to order some fiber pigtails (fiber cables with only one connector mounted) and then splice the pigtail to the unterminated end of the cable. This is a quick and easy approach. However, it requires that you already have the fusion splicers (which could cost you tens of thousands of dollars). Or you would have to choose the less reliable mechanical splicing.
Field Termination Choices:
1. Field installation of epoxy and polish connectors
Lots of experience technicians still prefer this way since it provides the best flexibility and the lowest possible cost. Epoxy and polish connectors are the same as used by factories. You pull the fiber first, and then terminate the fiber on the site. This involves fiber optic epoxy, high temperature curing oven, scribe tools, polishing films and fiber optic inspection microscopes. This approach needs you already have a termination kit that includes these items.
2. Field installation of quick termination connectors
Quick termination connectors are a god bless for emergency repairs. This type of connector functions like a fiber optic pigtail. It is pre-polished in the factory. It has a fiber stub in the connector body. You just need to cleave your fiber, insert it into the connector body, and lock it per the connector manufacturer's instruction. However, it doesn't provide as much long term reliability as the epoxy and polish connectors. Also, quick termination connectors are much more expensive then standard epoxy and polish connectors.
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