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Network Interface Cards And Cabling Types
There are 5 common
parts that every network generally contain. They are the
Nodes, the cables, the connectors, the Network Operating
System, and the Network Interface Card, or NIC. NICs are
the device that transfer the signals from the cables to the
nodes, and are one of the more important aspects of networking.
NICs
Network Interface
Cards provide a physical link for the network cabling into the
computer. More than this, they provide a logical link to
the node as well. NICs are as important for determining
network topology as the cabling itself, and each NIC has it's
own standards and architectures.
NIC's plug into
expansion slots on the motherboard, both PCI and ISA.
They come in both Plug-and-Play and non-PnP styles, with the
PnP-enabled cards being much easier to connect. Non-PnP
cards use either dip switches or software to program, and are
much more difficult to avoid conflicts with. Therefore,
if you have a PnP BIOS and operating system, use a PnP
NIC. It is also suggested that you always buy one
specific card brand for all the nodes in a
network. This is to avoid differences in
attenuation and electrical signaling that can slowly corrupt
one of the cards over time.
NICs are serial
devices, in that they transmit information one bit at a
time. The bus structure of a computer is parallel,
moving data up to 64 bits at a time. Much like a modem,
a NIC converts the parallel data stream into a serial stream
that the network cabling can transmit, and vice
versa.
Network
Cabling
There are four basic
types of cable connections used in networking today.
Coaxial and twisted pair cables transmit electrical signals
across copper wires. Fiber optic cables use light
transmitted across a glass or plastic filament. Radio
Wave signals don't use wires at all, and send signals through
the air. Each of these methods is described
below;
| Cable |
Formats |
Description |
| Coaxial |
Coaxial cable is much like the
cable that runs from your cable TV feed to your
Television, except it uses a different
impedance. |
| Thick Coaxial |
A solid center copper wire surrounded by a mesh
shielding wire, separated by a foam or plastic
insulator. This is called Thicknet, and uses
vampire clamps to connect to the transceiver
modules. This cable can be used in lengths up to
500 meters. |
| Thin Coaxial |
The same as thick coaxial cable, but thinner and
with less shielding and a core made of stranded
wire. It is called thinnet, and uses wires rated
as RG-58 A/U. It is capable of lengths of 185
meters, and is less expensive than
thicknet. |
| Twisted Pair |
Twisted pair cables look much like
your telephone cabling, with larger connectors.
This cable is twisted a certain number of times per
inch. |
| Unshielded Twisted Pair
(UTP) |
Four pairs of wires are wrapped in a plastic
sheath and connected with RJ-45 connectors. Each
set of wires twists a certain number of times per inch
to eliminate interference between wires and from outside
sources. The wires can be either stranded or
solid. |
| Shielded Twisted Pair
(STP) |
The same as UTP, except a metal shield wraps
around the the wire bundle to eliminate more
interference. STP is faster than UTP, but more
expensive. |
| Fiber-Optic |
Plastic Or Glass |
Fiber-Optic
cables use either glass or plastic to transfer a light
signal from end to end. Because it travels at the
speed of light, it is the fastest communication method,
but also the most expensive. It is resistant to
interference and small in size, but difficult to install
and requires more skill to use properly. |
| Wireless |
Wireless systems are used were
normal cabling can not be used. If great distances
must be traveled or cables can not be run, wireless
systems provide a necessary but expensive
solution. |
| Infra-red |
Using Infra-red emitters, these types of
connections can be used for small networks where cables
can not be laid as an entire network media, or as a
point-to-point signaling method over medium
distances. |
| Radio Frequency |
Radio frequency (RF) is used where longer
distances are needed or cables can not go. Signals
wary in strength (Amplitude) and tone (Frequency) in
order to offer a broad range of services, from
short-range to extremely long-range. |
| Microwave |
Microwave transmissions are normally used in
satellite communications, and are point-to-point
transmissions. They are meant for extremely
long-range communications, and are extremely
expensive. |
**Note - Twisted Pair
cables are rated by category, with higher numbers meaning
better protection from interference. Remember that you
must use at least Category 3 cabling, with Category 5e being
preferred.**
Connectors
There are three basic
connectors used by these cables. The BNC connector is
used to connect thinnet cabling, while vampire clamps are used
for thicknet. Finally, RF-45 connectors (they look like
a large phone connector with 8 connectors instead of 4) are
used on twisted pair cables. Fiber-optic and wireless
signals use their own proprietary connector that are dependant
on the NICs and other equipment used.
Network
Architectures
There are many
different network architectures, they are;
-
Ethernet -
The cheapest and most commonly used network
architecture. It can use coaxial, twisted pair, and
fiber cables, and can work at either 10Mbps or 100Mbps.
(Mbps = Megabits per second) 100Mbps is called fast
ethernet.
-
Token Ring -
Named after the Ring shape the network uses. It can
also use both copper and fiber cables, and operates at
either 4mbps or 16mbps. Token Ring networks have
self-healing properties that make them very reliable, but
can be difficult to install and troubleshoot.
-
FDDI (Fiber
Distributed Data Interface) - Used fiber optic cable to send
signals at 100Mbps and above. It an not be used for
copper cabling, and uses a ring topology. It is most
commonly used for backbone networks. (Networks using high
speeds to connect several smaller
networks.)
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