A Local Area Networks connects computers together to
exchange data. Apart from the computers, and other devices like printers and
faxes, a LAN has to have six essential components to function.
Network Adapter
A
computer needs a network adapter to connect to a network. It converts computer
data into electronic signals. It listens for silence on the network cable and
applies the data to it when it has an opportunity. The network access element
of its job is called Media Access Control, or MAC. The physical address of
every computer on a network is called its MAC address. The MAC address is the
network adapter's serial number. Most computers are shipped with the network
adapter integrated into the motherboard. However, early PCs didn't include this
function and computer owners had to buy it separately and fit it into an
expansion slot on the motherboard. These were called "network cards"
because they were sold on a separate card. Although network adapters are now
integrated, the name network card is still used. The wireless equivalent is
called a Wireless Network Interface Controller.
Network Medium
Wired
networks need cable. The most common form of
cable used in networks is called
the "Unshielded Twisted Pair." In PC shops, it is generally just
referred to as "network cable" or "Ethernet cable."
Ethernet is the most widely implemented set of standards for the physical
properties
of networks. UTP is so closely identified with Ethernet that it is
often given that name. Other cable types used for networks are twin-axial,
Shielded Twisted Pair and single-mode and multi-mode fiber optic cable.
Wireless networks don't need cable; they send data on radio waves generated by
the WNIC.
Cable Connectors
In
wired networks, the most common form of connector is the RJ45. Every computer
with networking capabilities has an RJ45 port. This is sometimes called a
"network port" or an "Ethernet port." The RJ45 plug looks
like a slightly larger telephone plug and connects the Unshielded Twisted Pair
or the Shielded Twisted Pair cable.
Power Supply
Both
wired and wireless networks need a power supply. A wireless network uses the
current to generate radio waves. A cabled network sends data interpreted as an
electronic pulse.
Hub/Switch/Router
In
wired networks, one computer cannot connect to many others without some form of
splitter.
A hub is little more than a splitter. It repeats any signals coming
into one of its ports out onto all its other ports. A cable leads from each
port to one computer. A switch is a more sophisticated version of a hub. It
only sends the signal on to the computer with the address written in the
arriving message. Routers are much more complicated and are able to forward
messages all over the world. Larger networks sometimes use routers for their
LAN traffic. The wireless networking device is called a "wireless
router."
Network Software
Software
on a communicating computer packages data into segments and puts that data into
a structure called a "packet." The source and destination addresses
of the packet are written into the header of the packet. The receiving computer
needs to interpret these packets back into meaningful data and deliver it to
the appropriate application.
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