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Normally one user
can use only one Computer (Micro-Computer or PC); similarly a PC (Personal
Computer) can handle only one user’s task at a time.
In large
organization, where several Computers (PCs) are installed; there we often need
to transfer files/packages etc. from one Computer to another, we have to
communicate with each other and above all we have to centralize our data (all
data at one place/Computer).
For this purpose we
connect all installed PCs through special wires with each other. One of these
PCs (comparatively powerful and having large capacity hard disk) becomes master
Computer while other ones slave Computers. This wiring etc. is done in such a
way that when we use these slave Computers, all data/packages are retrieved
from master Computer. Similarly when we save our files, so these files are
automatically saved in master Computer.
Technically master
Computer is called File Server while Slave Computers are called Workstations or
Clients. This whole setup is called Network. A network system becomes active in
presence of a special Software called Network Operating System (NOS).
1) LAN (Local Area
Network)
2) WAN (Wide Area
Network)
Talking about
definition of LAN; it is a network of Computers connected by special types of
transmission media (such as cables) and network adapters and overseen by any of
number of network operating systems that support all necessary communications
protocols and standards.
A LAN typically
spans single office or workgroup, a few floors in a building, or a few
buildings in a campus-like setting.
In WAN Computers of
the entire world (if network facility is available) are connected to each other
and it is easy to communicate with each other all around the world
A network either
allows one or multiple computers to connect to each other (LAN for Local Area
Network), or it allows them to connect to the Internet (WAN or Wide Area
Network). Some networks are configured to allow both. In domestic applications,
networking usually consists of allowing the computers in a household to share
the same printer, to send and receive files between computers in the house, and
to connect the computers to the Internet.
In order for a
computer to be able to talk to other computers, or to an Internet service
provider, it needs what is called a Network Interface Card, or NIC. This
card, usually found inside the computer, is the gateway into which you plug an
ethernet cable. The ethernet cable resembles a telephone wire, though slightly
larger in diameter and its end is about twice the size of a standard RJ11 jack.
An ethernet cable is standard for connecting your computer to a high-speed
Internet modem, or to a network within your home.
Network Topology
The physical
configuration of a network that determines how the network's computers are
connected. Common configuration include the bus topology, mesh topology, ring
topology, star topology, and tree topology. See each of these topology
definitions for additional information and a visual examples.
Bus
topology
A type of network
setup where each of the computers and network devices are connected to a single
cable. Below is a visual example of a simple computer setup on a network using
the bus topology.
Mesh
topology
A type of network
setup where each of the computers and network devices are interconnected with
one another allowing for most transmissions to be distributed even if one of
the connections go down. This type of topology is not commonly used for most
computer networks as it is difficult and expensive to have redundant connection
to every computer. However, this type of topology is commonly used for wireless
networks. Below is a visual example of a simple computer setup on a network
using a mesh topology.
Ring
topology
Also known as a
ring network, the ring topology is a type of computer network configuration
where each network computer and device are connect to each other forming a
large circle (or similar shape). Each packet is sent around the ring until it
reaches its final destination. Today the ring topology is seldom used. Below is
a visual example of a simple computer setup on a network using a ring topology.
Star topology
Also known as a
star network a star topology is one of the most common network setups where
each of the devices and computers on a network connect to a central hub. A
major disadvantage of this type of network topology is that if the central hub
fails all computers connected to that hub would be disconnected. Below is a
visual example of a simple computer setup on a network using the star topology.
Tree topology
Also known as a star
bus topology, tree topology is one of the most common types of network
setups that is similar to a bus topology and a star topology. A tree topology
connects multiple star networks to other star networks. Below is a visual
example of a simple computer setup on a network using the star topology.
Hub
NIC
ABCs
A NIC, or Network Interface Card,
is a circuit board or chip, which allows the computer to communicate to other
computers on a Network. This board, when connected to a cable or other method
of transferring data such as infrared, can share resources, information and
computer hardware. Local or Wide area networks are generally used for large
businesses as well as are beginning to be found in homes as home users begin to
have more than one computer. Utilizing network cards to connect to a network
allow users to share data such as companies being able to have the capability
of having a database that can be accessed all at the same time, send and
receive e-mail internally within the company, or share hardware devices such as
printers.
CONNECTORS
Network cards have three main types
of connectors. Below is an example of what a network card may look like.
BNC - As illustrated in the above picture, the
BNC connector is a round connector which is used for Thinnet or 10Base-2 Local
Area Network.
DB9 (RJ45 JACK) - The DB9 connector, not to be confused with
the Serial Port, or sometimes referred to as the RJ45 JACK, not to be confused
with the RJ45 connection, is used with Token Ring networks.
DB15 - The DB15 connector is used for a Thicknet or
10Base-5 Local area network.
RJ45 - Today, one of the most popular types of
connections used with computer networks. RJ45 looks similar to a phone
connector or RJ11 connector but is slightly larger.
LED -The LEDs, as shown in the above
illustration, indicates if it detects a network; generally by a green light
which may flash as it communicates, and then a red light which indicates
collisions which will generally flash or not flash at all.
CABLES
Below is a few examples of some of
the more commonly used types of cables found with networks.
As illustrated in the above
picture, you can see three of the main types of cables used today. The first
two pictures illustrate Unshielded and Shielded twisted pair cables. Unshielded
twisted-pair cable is generally found in phone cables today and are used more
often than shielded twisted pair today as it has been found that simply
twisting the cable provides more efficient means of protection against
interference. In addition, shielded twisted-pair cable required the one end of
the cable to be grounded. If both ends were to be grounded, this would cause a
grounding loop causing low voltage and infinite amperage and various other
hazards to the network.
The third picture in the above
illustration shows a coaxial cable which is the most commonly used and known
types of cables. This cable can be found for cable TV and when used with
networks utilizes the BNC connector.
TCP/IP
Short for Transmission
Control Protocol/Internet Protocol, TCP/IP was developed by the U.S.
Department of Defense and is a language governing communications among all
computers on the Internet.