Page 423 - StudyBook.pdf

Infrastructure Security: Devices and Media • Chapter 6 407

Fiber Optic

Fiber-optic cable (or fiber) is the latest and greatest in network cabling. Fiber is basi-
cally a very thin piece of glass or plastic that has been stretched out and encased in a
sheath. It is used as a transport media, not for electrons like the copper cable used in
coax or UTP/STP, but for protons. In other words, fiber-optic cables transport light.
An optical transmitter is located at one end of the cable with a receiver at the other
end.With this in mind, it takes a pair of fiber-optic lines to create a two-way com-
munications channel.
Fiber has many advantages over coax and UTP/STP. It can transfer data over
longer distances at higher speeds. In addition, it is not vulnerable to EMI/RFI
interference, because there is nothing metallic in the fiber-optic cable to conduct
current, which also protects it from lightning strikes. Unlike coax and UTP/STP,
fiber optics cannot succumb to typical eavesdroppers without actually cutting the
line and tapping in with a highly complex form of optical T-connector, and when
attempted creating a noticeable outage.
The complexity of making connections using fiber is one of its two major
drawbacks. Remember that these cables carry light that makes them rather unfor-
giving.The connection has to be optically perfect or performance will be down-
graded or the cable may not work at all.The other major drawback is cost. Fiber is
much more expensive than coax or UTP/STP, not only for the cable, but also for
the communications equipment.When dealing with optical equipment, costs usu-
ally at least double or triple.
The Security+ exam expects you to know about the advantages and disadvan-
tages of this type of network media.You will also need to know how fiber com-
pares and contrasts with coax and UTP/STP. Generally, fiber is used in data centers
or for runs between buildings, and UTP cabling is used for connections to users’
workstations.

EXAM WARNING
Choosing the right network media to use in a given situation is part of
the Security+ exam. There are always situations when one type of cable
is more appropriate than another type. For example, if you are putting
cabling into a location with a lot of EMI, you will want to use STP or
fiber to ensure that the network connection is reliable.
It is also important to keep safety in mind when installing cabling.
When the plastic sheath of some cabling catches on fire it releases toxic
fumes. There is a special type of sheathing material used to prevent this

www.syngress.com