Overview of Networking
2-12
The Classification of Networks
Fiber optic cabling is made up of a glass strand, the core, which allows for the
easy transmission of light; the cladding, a glass layer around the core which helps
keep the light within the core; and a plastic buffer which protects the cable.
Figure 2-5. Fiber Optic Cable Cross-Section
There are two basic types of fiber optics: multimode and single mode. The names
come from the types of light used in the transmission process.
Multimode Fiber Optics
Multimode fiber optic cabling uses inexpensive Light Emitting Diodes (LEDs) to
produce the signals that travel through the core of the cable. Due to the nature of
the LED, the signal produced is made up of a number of differing wavelengths of
light, fired outward from the center of the LED. Not all the rays of light enter the
fiber, and those that do often do so at an angle, which reduces the amount of
distance the signal can effectively cover.
Single Mode Fiber Optics
Single mode fiber optics, driven by the concentrated beams of light which can
only be produced by lasers, are constructed in the same fashion as multimode
fiber optics, but may use a narrower core strand. The use of lasers to drive the
signal greatly increases the expense involved in producing single mode fiber optic
devices as opposed to multimode fiber optic devices. The expense involved in
single mode fiber optic equipment often causes it to be reserved for applications
requiring its ability to traverse much greater distances than multimode fiber
optics.
Single mode fiber optics and their hardware can transmit and receive signals at
distances of 3 kilometers (1.8 miles) or more. As such, it is often best reserved for
extremely long-distance LAN communications.
NOTE
While the media is capable of supporting these distances, the
technology being used may not be able to function with a link of
that distance. Be sure to remain within the maximum distances and
limitations imposed on any network technology by the appropriate
IEEE or ANSI standard.
Transmissive Core
Cladding
PVC Buffer (Jacketing)
1706n05
Summary of Contents for MMAC-5FNB
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