Network Interface Card and Cabling
To attach personal computers to the LAN, you must
install a network interface card (NIC) into an empty
expansion slot in the PC, install the appropriate
software, and attach the network cable to the NIC. The
other item you need to consider is what type of
connector to use. But before deciding the type of
connector to use, you need to know what type of cable
and architecture you will be using. The cables may be
twisted-pair cable, fiber optic cable, or coaxial cable.
l Twisted-pair cable The twisted-pair cable is
easy to install and costs little on a per-foot basis. In
some cases existing telephone cable may be used. Its
disadvantages include limitations in capacity and
speed. It is also susceptible to electrical interference
unless it is shielded.
l Fiber optic cable Fiber optic cable is the best
choice if a secure network is needed. Because the cable
transmits light, the transmissions are immune to
interference caused by electrical or electronic devices.
Also, if your network will run through an area of heavy
industrial activity or a work place with strong radio
frequency interference, fiber optic cable is the most
appropriate choice. Other advantages of the fiberoptic
cable are that it lasts longer than other cable and can
carry many more channels. Its disadvantages include its
high price, poor connectivity, and low flexibility.
l Coaxial cable Coaxial cable, also called coax,
networks have gained in popularity because of their use
in cable television. The quantities of cable and
connectors produced for cable television have greatly
reduced the prices of these components for network
users. Coaxial cable comes in various thicknesses and
is designated by a number: RG-11, RG-58, RG-59,
RG-62, etc. You can use either baseband or broadband
transmission methods with coaxial cable.
Baseband coaxial systems, which transmit digital
signals unchanged over a single channel, have several
advantages. They are inexpensive, simple, easy to
install, and have low maintenance. They also allow
very high data transmission rates. One disadvantage is
they are limited to transmitting digital signals only.
In contrast, broadband coaxial systems require
the digital signal to be converted to an analog signal
before transmission and then back to digital by modem
at the receiving device. Broadband systems support
data, voice, and video signals that may be transmitted
simultaneously. Disadvantages of broadband systems
are their higher installation costs and complex
maintenance.
Connectors
The connector provides the physical link between
two components. For example, a connector can link a
cable and a NIC, a cable and a transceiver, or two cable
segments.
Connectors differ in their shape, size, gender,
connection mechanism, and function. These features
influence and determine where a connector can be used.
Where necessary, special adapters may be used for
connections involving different connector
combinations.
Connectors also differ in how sturdy they are, how
easily and how often they can be attached and detached,
and in how much signal loss there is at the connection
point.
The type of connector needed in a particular
situation depends on the components involved and, for
networks, on the type of cable and architecture being
used.
CONNECTOR FUNCTIONS. A connector
may be passing the signal along or absorbing it. A
connector that passes a signal along may pass it
unmodified or may clean and boost it. Connectors can
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serve a variety of purposes, including the following:
Connect equal components, such as two
segments of thin coaxial cable
Connect almost equal components, such as thin
to thick coaxial cable
Connect unequal components, such as coaxial to
twisted-pair cable
Connect complementary components, such as a
NIC to a network
Terminate a segment
CONNECTOR SHAPES. Specially shaped
connectors are used for particular types of connections
or for connections in particular locations. For example,
a T-connector attaches a device to a cable segment; an
elbow connector allows wiring to meet in a corner or at a
wall.
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