Information Technology Reference
In-Depth Information
Fiber optics has an important place in LAN wiring. Fiber can generally support
faster applications over longer distances than copper cabling. Fiber is also the first
medium chosen for implementing new high-speed technologies, such as gigabit and
10 Gigabit Ethernet. Fiber-optic cabling occupies an increasingly important place in
the networking arena and it is important to understand this key technology.
Optical fiber was initially used for intercity telecommunications links to
replace antiquated and overloaded microwave links at a lower cost than satellite
links. In this application, T-carrier links, and later SONET links, provided exten-
sions of the telecommunications services over long distances. The intercity fiber fea-
tured advantages of long range, wide bandwidth, interference immunity, and
relatively low installation cost, compared to the bandwidth provided. In fact, it was
this lower-cost, relatively high bandwidth fiber-optic technology that fueled the
modern wide area communications revolution.
In the wide area, the availability of right-of-way for fiber cable installation was the
key to building a fiber network. One of the earliest implementers utilized partnerships
with railway companies to place fiber along rail lines from coast to coast. International
communications also benefited from this technology, as literally thousands of fibers of
fiber-optic cable were placed along the ocean beds between continents.
The development of this high-volume intercity fiber network required signifi-
cant advancements in the technology of both optical fiber and optical transceivers.
As the technology moved forward, devices and materials became available for use
in the bandwidth-hungry LAN domain as well.
LANs have quickly adopted faster data transmission technologies during the
same period of time. These data topologies, such as gigabit and 10 Gigabit Ethernet,
require high transmission bandwidths and have really put twisted-pair copper to the
test. Fiber-optic cable, in contrast, has a vastly superior bandwidth capability, par-
ticularly at the shorter distances prevalent in LANs.
The focus of this chapter will be to provide a concise explanation of the utility of
fiber-optic technology in the LAN environment. We will explore the many facets of
fiber-optic technology as they relate to LAN applications. Some of these topics overlap
wiring technologies that are covered in other parts of this topic. We will repeat the key
points here with reference to chapters in the topic for supplementation where appro-
priate. Fiber-optic components are an integral part of structured cabling and may be
used in concert with copper components, with each technology doing what it does best.
Before we delve into the LAN applications, let's review the basics of fiber-optic tech-
nology. We need to understand how optical transmission works and what the key
terms and parameters are.
