A networking is any collection of independent computers
that communicate with one another over a shared network
medium. A computer network is a collection of two or
more connected computers. When these computers are
in a network, people can share files and peripherals such as
modems, printers, tape or CD-ROM
drives. When networks at multiple locations are connected
using services available from phone companies, people
can send e-mail, share links to the global Internet, or
conduct video conferences in real time with other remote
In the simple word if the more then two computer
connected to each other to share there resource (hared
ware and software) and they are able to send and receive
data and information from one location to another
Every networking includes
At least two computers Server or Client workstation.
Networking Interface Card's (NIC)
A connection medium, usually a wire or cable, although wireless
networked computers and peripherals is also possible.
Network Operating system software, such as Microsoft Windows NT or
2000, Unix and Linux.
Types of networkingComputer networking is divided in to two types:
On the Bases of architecture
On the bases of geographical area
On the Bases of architecture: On the bases of architecture
computer network is classified in to two types :
1- Client server network.
2- Peer to peer network.
Client server and peer to peer
Client server network: The client server networking there is a
dedicated server, A dedicated server function as a server only not as a
client. All the client computer are controlled and manage my server
Peer to peer network:
In peer to peer network there are no dedicated servers or hierarchy
among the computers. All of the computers are equal and therefore
as peers. Normally each computer serves as Client/Server and there is no
one assigned to be an administrator responsible for the entire network.
Peer-to-peer networks are good choices for needs of small organizations
where the users are allocated in the same general area.
On the bases of geographical are:
These network are classified in to three types they are
LAN: A network is any collection of independent computers that
communicate with one another over a shared network medium. LANs are
networks usually confined to a geographic area, such as a single building or a
college campus. It can be small, linking as few as three computers, but often
link hundreds of computers used by thousands of people. In the simple
word if more then two computers are interconnected to each other with in
building , office to share there resource and they are able to send and receive
the information from one location to another location and maximum
distance is 0 to 10 KM. For example Ethernet.
It stands for metropolitan Area network. A MAN is a network which is larger then a
LAN. It is called metropolitan because it covers area of city about 10 to 100 km.if the
more then two computers are able to share there resource and they send and receive
data with in city such type of network is called MAN for example Entrant.
WAN: It stands for wide area network. Wide area networking combines multiple
LANs that are geographically separate. This is accomplished by connecting
the different LANs using services such as dedicated leased phone lines, dial-up
phone lines (both synchronous and asynchronous), satellite links, and data
packet carrier services. Wide area networking can be as simple as a modem and
remote access server for employees to dial into, or it can be as complex as
hundreds of branch offices globally linked using special routing protocols and
filters to minimize the expense of sending data sent over vast distances. In the
simple word it is larger then MAN. WANS interconnected LANs which may be
opposite side of country. This is located around the world. For Example internet
The OSI Model
Open System Interconnection (OSI) reference model has
become an International standard and serves as a guide
for networking. This model is the best known and most
widely used guide to describe networking environments.
Vendors design network products based on the
specifications of the OSI model. It provides a description
of how network hardware and software work together in
a layered fashion to make communications possible. It
also helps with trouble shooting by providing a frame of
reference that describes how components are supposed
Physical Layer, is just that the physical parts of the network such as wires,
cables, and there media along with the length. Also this layer takes note of the
electrical signals that transmit data throughout system.
Data Link Layer, this layer is where we actually assign meaning to the
electrical signals in the network. The layer also determines the size and format
of data sent to printers, and other devices.
Network Layer, this layer provides the definition for the connection of two
Transport Layer, this layer allows data to be broken into smaller packages for
data to be distributed and addressed to other nodes (workstations).
Session Layer, this layer helps out with the task to carry information from
one node (workstation) to another node (workstation). A session has to be
made before we can transport information to another computer.
Presentation Layer, this layer is responsible to code and decode data sent to
Application Layer, this layer allows you to use an application that will
communicate with say the operation
Network protocols are standards that allow computers to communicate.
A protocol defines how computers identify one another on a network, the
form that the data should take in transit, and how this information is
processed once it reaches its final destination. In the simple word
protocol is a set of rules which is used to send and receive data and
information in the network. for example FTP,TCP/IP ,etc.
TCP/IP :TCP stands for Transmission Control Protocol and IP stands for
Internet Protocol. The term TCP/IP is not limited just to these two
protocols, however. Frequently, the term TCP/IP is used to refer to a
group of protocols related to the internet. This network is basically used
to control transmission information and data.
Telnet: Used to connect to a host and emulate a terminal that the remote
server can recognize in the network.
FTP Used to send and receive files from a remote host and it is used to
upload and download files from client to server and server to client.
HTTP:Used for the web to send documents that are encoded in HTML.
SMTP: It is used to E-Mail over the internet.
Telnet:Used to connect to a host and emulate a terminal that the remote
server can recognize in the network.
Network topologies describe the ways in which the elements of network
are mapped. They describe the physical and logical arrangement of the
network nodes. The physical topology of a network refers to the
configuration of cables, computers, and other peripherals. In the simple
way computer topology is a arrangement of computer, wires and
components in the network. There are six types of topology they are :
Types of topology
All the nodes (file server, workstations, and peripherals) on a bus topology are
connected by one single cable. A bus topology consists of a main run of cable
with a terminator at each end. All nodes (file server, workstations, and
peripherals) are connected to the linear cable. Popular on LANs because they
are inexpensive and easy to install.
Advantages of Bus Topology
It is Cheap, easy to handle and implement.
Require less cable
It is best suited for small networks.
Disadvantages of Bus Topology
The cable length is limited. This limits the number of stations that
can be connected.
This network topology can perform well only for a limited number of nodes.
In a ring network, every device has exactly two neighbors for communication purposes. All
messages travel through a ring in the same direction. A failure in any cable or device breaks the
loop and can take down the entire network. To implement a ring network we use the Token
Ring technology token, or small data packet, is continuously passed around the network.
When a device needs to transmit, it reserves the token for the next trip around, then attaches
its data packet to it.
Advantage of Ring Topology
Very orderly network where every device has access to the token and the opportunity to
Easier to Mange than a Bus Network
Good Communication over long distances
Disadvantages of Ring Topology
The failure of a single node of the network can cause the entire network to fail.
The movement or changes made to network nodes affects the performance of the entire
In a star network, each node (file server, workstations, and peripherals) is connected to a
central device called a hub. The hub takes a signal that comes from any node and passes
it along to all the other nodes in the network. Data on a star network passes through the
hub, switch. The hub, switch, or concentrator manages and controls all functions of the
network. The star topology reduces the chance of network failure by connecting all of the
system to a central node.
Advantages of Star Topology
Easy to manage
Easy to locate problems (cable/workstations)
Easier to expand than a bus or ring topology.
Easy to install and wire.
Easy to detect faults and to remove parts.
Disadvantages of Star Topology
Requires more cable length than a linear topology.
If the hub or concentrator fails, nodes attached are disabled.
More expensive because of the cost of the concentrators.
A tree topology (hierarchical topology) can be viewed as a collection of star
networks arranged in a hierarchy. This tree has individual peripheral nodes which
are required to transmit to and receive from one other only and are not required to
act as repeaters or regenerators. The tree topology arranges links and nodes into
distinct hierarchies in order to allow greater control and easier troubleshooting.
This is particularly helpful for colleges, universities and schools so that each of the
connect to the big network in some way.
Advantages of a Tree Topology
Point-to-point wiring for individual segments.
Supported by several hardware and software vendors.
All the computers have access to the larger and their immediate networks.
Disadvantages of a Tree Topology
Overall length of each segment is limited by the type of cabling used.
If the backbone line breaks, the entire segment goes down.
More difficult to configure and wire than other topologies.
In this topology, each node is connected to every other node in the network.
Implementing the mesh topology is expensive and difficult. In this type of network,
each node may send message to destination through multiple paths. While the data
is travelling on the Mesh Network it is automatically configured to reach the
destination by taking the shortest route.
Advantage of Mesh Topology
No traffic problem as there are dedicated links.
It has multiple links, so if one route is blocked then other routes can be used for
Points to point links make fault identification easy.
Disadvantage of Mesh Topology
There is mesh of wiring which can be difficult to manage.
Installation is complex as each node is connected to every node.
Cabling cost is high.
A combination of any two or more network topologies. A hybrid topology
always accrues when two different basic network topologies are connected. It is
a mixture of above mentioned topologies. Usually, a central computer is
attached with sub-controllers which in turn participate in a variety of
Advantages of a Hybrid Topology
It is extremely flexible.
It is very reliable.
Disadvantages of a Hybrid Topology
Various physical media can used for actual transmission of information from
one place to another place. The transmission media generate path way between
sender and receiver. Each transmission media has its own properties like
speed,cost,error rate. In the simple word transmission media is path way
networked entities use to connect each other.
The transmission media includes cable and wireless technology that allow
networked device to contact each other. But transmission cannot guarantee
that other network device will understand a message. it is divided in to two
types : Guided and unguided media
Guided media, which are those that provide a conduit from one device to
another, include twisted-pair cable, coaxial cable, and fiber-optic cable. In
guided media the
Communication happen throw wires and cable is called guided media. it is
further divided in to three types.
Types Of Guided Media
The wires in Twisted Pair cabling are twisted together in pairs. Each pair
would consist of a wire used for the signal. Any noise that appears on 1 wire of
the pair would occur on the other wire. This wire is a common schema using e
for using copper wire as a telecommunication cable. This cable consist of two
insulated strands of copper wire which are twisted with each other.
Coaxial cable is made of two conductors that share a common axis
Coaxial Cable consists of 2 conductors. The inner conductor is held
inside an insulator with the other conductor woven around it providing
a shield. An insulating protective coating called a jacket covers the
outer conductor. The outer shield protects the inner conductor from
outside electrical signals. The excellent control of the impedance
characteristics of the cable allow higher data rates to be transferred
than Twisted Pair cable.
Fiber optic cable
optic cable is made of a glass or plastic core surrounded by
more glass which is called cladding. A fiber optic cable
consist of a bundle of glass threads, each of which is
capable of transmitting message modulated on to light
The unguided media we have microwave system, communication
satellite system which are used connect other component in the
network. In the simple word Unguided media transport
electromagnetic waves without using a physical conductor. This type of
communication is often referred to as wireless communicate.
Types of unguided media
A satellite is an object built and placed by human in
earth orbit. These are also called artificial satellite
because these man made. These satellite uses
microwave transmission frequency . Satellites are used
for different purpose ,common type include military,
communication,weatherforcasting and research.
Microwaves are used for uncast communication such as cellular
telephones, satellite networks, and wireless LANs.Higher
frequency ranges cannot penetrate walls. Use directional
antennas -point to point line of sight communications.
Infrared signals can be used for short-range communication in a
closed area using line-of-sight propagation.
Mode of communication
The mode of communication shows how . two or
more devices communicate each other. They are three
Simplex: in simplex communication one of the
communicating devices can only send data where
other can only receive it.Radia, TV are the example of
Half Duplex: Half Duplex refers to two way
communication but only one can transmit data at a
time. when one device sending data the other device
only receive and vice versa. walkie talkie.
Full Duplex: in full duplex both devices are capable of
sending and receive the data at the same time
.Bidirectional communication at the same time.