1. Introduction to LAN
Components.
(a) Cabling.
(b) Hubs.
(c) Switches.
(d) Transceivers.
(e) NIC Cards.
(f) Practical
Handling.
(g) Installation and
Troubleshooting.
2. Cabling. Some
sort of wire or cabling today connects the vast majority of networks, which act
as the network transmission medium carrying signals between computers. There is
a variety of cable that can meet the varying needs and sizes of networks, from
small to large. Cabling can be confusing. Belden, a leading cable manufacturer,
publishes a catalog that lists more than 2,200 types of cabling. These cable
are also known as (Adaptor User Interface (AUI) Cables. Fortunately, only three
major groups of cabling connect the majority of networks-
(a) Co-axial Cables.
(b) Twisted Pair
Cables .
(c) Fiber Optics .
3. Co-axial Cables.
Although no longer widely used to create new networks, coaxial cable is
commonly found on older networks. Coaxial cable must be linked using devices
called British Naval Connectors (BNCs). A BNC connector that links a computer
or other device .to a coaxial cable is called a T-connector.
4. Shielded Twisted Pair
Cable. Shielded Twisted Pair (STP) cable is similar to unshielded twisted
pair cable, except that shielded twisted pair cable includes a protective metal
or foil covering. A shielded twisted pair cable can contain a single pair of
wires or several pairs of wires.
5. Unshielded
Twisted-Pair Cables. Twisted-pair uses RJ-45 telephone connectors to
connect to a computer-
(a) Jack Couplers.
These single or double RJ-45 jacks snap into patch panels and wall plates and
support data rates to 100 Mbps.
(b) Wall Plates.
These support two or more couplers. Wall plates provide multiple outlets for
extension of LANs. Rj-45 is similar to the RJ-11 telephone connector. Although
they look alike at first glance, there are crucial differences between them.
The RJ-45 is slightly larger, and will not fit into the RJ-11 telephone jack.
The RJ-45 houses eight cable connections, while the RJ-11 only houses four.
6. Fiber
Optic Cable. In fiber-optic cable, optical fibers carry digital data
signals in the form of modulated pulses of light. This is a relatively safe way
to send data because no electrical impulses are carried over the fiber-optic
cable. This means that fiber-optic cable cannot be tapped and the data stolen,
which is possible with any copper-based cable
carrying data in the form
of electronic signals. Fiber-optic cable is good for very highspeed,
high-capacity data transmission because of the lack of attenuation and the
purity of the signal.
7. Fiber-Optic
Composition Optical fiber consists of an extremely thin cylinder of glass,
called the core, surrounded by a concentric layer of glass, known as the
cladding. The fibers are sometimes made of plastic. Plastic is easier to
install, but cannot carry the light pulses as far as glass. A reinforcing layer
of plastic surrounds each glass strand while Kevlar fibers provide strength.
Each glass strand passes signals in only one direction, so a cable consists of
two strands in separate jackets. One strand transmits and one receives. The
Kevlar fibers in the fiber-optic connector are placed between the two cables,
which are encased in plastic. Fiber-Optic Cable transmissions are not subject to
electrical interference and are extremely fast. They can carry a signal-the
light pulse-for miles.
8. HUBS . One
network component that is becoming standard equipment in more and more networks
is the hub. A hub is the central component in a star topology. There are three
types of Hubs.
(a) Active Hubs. Most
hubs are active in that they regenerate and retransmit the signals the same way
a repeater does. Active hubs require electrical power to run.
(b) Passive Hubs. Some
types of hubs are passive. They act as connection points and do not amplify or
regenerate the signal, the signal passes through the hub. Passive hubs do not
require electrical power to run.
(c) Hybrid Hubs. Advanced
hubs that will accommodate several different types of cables are called hybrid
hubs. A hub-based network can be expanded by connecting more than one hub.
9. Switches:-
(a) Switch is a device
that could support creating separate virtual or physical networking segments.
It has the ability to create separate collision domains either physically or
virtually.
(b) They operate at
the data link layer (or layer 2 in the OSI model), and higher in cases of a
multilayer switch. When operating at layer 2, a device has the ability to make
intelligent decisions on how to handle a given packet of data based on the
source and destination MAC (Media Access Control).
(c) A MAC address is
essentially a unique identifier that is hard-coded into every network device at
the time of production.
(d) Ethernet switches
are switch frames of data between ports Other network switches do exist for
example, frame relay switches are used largely by telecommunication carriers,
as are Asynchronous Transfer Mode (ATM) switches. ATM switches are differ
greatly from Ethernet switches in that they switch in cells and not frames.
(e) An Ethernet switch
may look similar to a hub, switches do not just receive a signal on one port and repeat to all other
ports.
10. Network Interface
Card (NIC). In networking the PC expansion board that plugs into a personal
computer or server and works with the network operating system to control the
flow of information over the network. The network interface card is connected
to the network cabling (twisted pair, coaxial or fiber optic cable), which in
turn connects al the network interface cards in the network
11. NIC Card
Installation :-
(a) Shut down the
computer, unplug its power cord and remove the chassis cover.
(b) Insert the Adaptor
card into the ISA/PCI expansion slot. Ascertain that the card is fully seated
in the expansion slot connector.
(c) Install the
bracket screw which secures the card to the computer chassis.
(d) Configure the card and run setup programme from
the installation CD/Floppy disk and then configure to the network.
