Networking connects computing devices together to share data. It allows devices to communicate through a mix of hardware like cables and wireless equipment, and software like communication protocols. Networks can be categorized based on their geographic reach - local area networks (LANs) span a small area like a home or office, while wide area networks (WANs) connect across cities, states or globally. The largest public WAN is the Internet. Networks also use common protocols like TCP/IP to define the language devices use to communicate. While wired networks were traditionally used, wireless networking has become more popular for new installations.

1. What is networking?
In the world of computers, networking is the practice of linking two or more
computing devices together for the purpose of sharing data. Networks are built
with a mix of computer hardware and computer software.
Area Networks
Networks can be categorized in several different ways. One approach defines the
type of network according to the geographic area it spans.Local area networks
(LANs), for example, typically reach across a single home, whereas wide area
networks (WANs), reach across cities, states, or even across the world.
The Internet is the world's largest public WAN.
Network Protocols
In networking, the communication language used by computer devices is called
the protocol. Yet another way to classify computer networks is by the set of
protocols they support. Networks often implement multiple protocols to support
specific applications. Popular protocols include TCP/IP, the most common protocol
found on the Internet and in home networks.
Wired vs Wireless Networking
Many of the same network protocols, like TCP/IP, work in
both wired and wireless networks. Networks with Ethernet cables predominated in
businesses, schools, and homes for several decades. Recently, however, wireless
networking alternatives have emerged as the premier technology for building
new computer networks.
Data communication
The distance over which data moves within a computer may vary from a
few thousandths of an inch, as is the case within a single IC chip, to as much
as several feet along the backplane of the main circuit board. Over such
small distances, digital data may be transmitted as direct, two-level
electrical signals over simple copper conductors. Except for the fastest
computers, circuit designers are not very concerned about the shape of the
conductor or the analog characteristics of signal transmission.

2. DIFFERENT NETWORK TOPOLOGIES
LAN NETWORKING
NETWORK TOPOLOGIES
TOPOLOGY – defines the structure of the network. There are two parts to the topology
definition: the physical topology which is the actual layout of the wire (media) and the logical
topology which defines how the media is accessed by the hosts. It refers also to how
computers are being connected with each other.
The types of topologies:
1. BUS TOPOLOGY
In the bus topology, the computers are connected through a common communication media. A
special type of central wire is used as communication media. This central wire is called Bus. The
computer are attached through the bus the ends of the bus are closed with the terminator .The
terminators are used to absorb signals. Bus topology use coaxial cables sections are connected
to the B. N. C connectors. B.N.C connectors are often use to connect the computer through the
main cable. These connectors can connect through two section of cable with the bus extending
in both directions. The end device on the bus have the terminals on one connectors of T
2.STAR TOPOLOGY
The star topology uses a separate cable for each work station as shown in fig.The cable
connects the work station to a central device typically a HUB. The configuration provides a more
reliable network that is easily expended. With star there is no central point of failure in the cable
.if there is a problem with the cable only the station connected to that cable is a effected .to add
more work stations simply connect another HUB
3.RING TOPOLOGY
In ring topology each computer is connected to the next computer and the last computer is
connected to the first computer. Thus a ring of computers is formed as shown in figure below.
4.MESH TOPOLOGY
A mesh network or mesh topology uses separate cable to connect each device to every other
device on the network, providing a straight communication path

3. HOSTS – devices that connect directly to a network segment. These hosts include
computers, both clients and servers, printers, scanners and many other devices. These
devices provide the users with connection to the network, with which the users share, create
and obtain information.
Network Interface Card (NIC) – is a printed circuit board that fits into the expansion slot of a
bus on a computer’s motherboard or peripheral device. It is considered to be found in Layer
2 devices because each individual NIC throughout the world carries a unique code, called
the Media Access Control (MAC) address.
You can build computer networks with many different media types. Each media has
advantages and disadvantages. What is an advantage for one media (category 5 cost) might
be a disadvantage for another (fiber optic cost). Some of the advantages and disadvantages
are:
Cost
Ease of installation
Cable length
REPEATER - is an electronic device that receives a signal and retransmits it at a higher
level and/or higher power, or onto the other side of an obstruction, so that the signal can
cover longer distances. It is used when the type of cable (CAT5 UTP) is long. CAT5 UTP
has a maximum length of 100 meters (approximately 333 feet). The purpose of a repeater is
regenerate and retimes network signals at the bit level to allow them to travel a longer
distance on the media.
HUB - is a device for connecting multiple twisted pair or fiber optic Ethernetdevices together
and thus making them act as a single network segment.
There are different classifications of hubs in networking:
1. The first classification is active or passive. Most modern hubs are active; they take energy
from a power supply to regenerate network signals. Some hubs are passive devices
because they merely split signal for multiple users, like using a “Y” cord on a CD player to
use more than one set of headphones.
2. Another classification of hubs is intelligent or dumb. Intelligent hubs have console ports,
which mean they can be programmed to manage traffic in the network. Dumb hubs simply
take an incoming networking signal and repeat it to every port without the ability to do any
management.
BRIDGE – refers to a device which has just two parts. It filters the frames and how this is
actually accomplished.
SWITCH – is to concentrate connectivity, while making data transmission more efficient. A
device that is able to combine the connectivity of a hub with the traffic regulation of a bridge
on each port.
ROUTER – the first device that you will work with that us at the OSI’s network layer, or other
known as Layer 3. The purpose of a router is to examine incoming packets, choose the best
path for them in a network and then switch them to the proper outgoing port

4. OSI model
The Open Systems Interconnection (OSI) model is a product of the Open Systems
Interconnection effort at the International Organization for Standardization. It is a prescription
of characterising and standardising the functions of a communications systemin terms
of abstraction layers. Similar communication functions are grouped into logical layers. A
layer serves the layer above it and is served by the layer below it.
OSI layers
OSI Model
Data unit Layer Function
Host
layers
Data
7. Application Network process to application
6. Presentation
Data representation, encryption and decryption,
convert machine dependent data to machine
independent data
5. Session
Interhost communication, managing sessions
between applications
Segments 4. Transport
End-to-end connections, reliability and flow
control
Media
layers
Packet/Datagram 3. Network Path determination and logical addressing
Frame 2. Data link Physical addressing
Bit 1. Physical Media, signal and binary transmission
LAN - Local Area Network
A LAN connects network devices over a relatively short distance. A networked
office building, school, or home usually contains a single LAN, though sometimes
one building will contain a few small LANs (perhaps one per room), and
occasionally a LAN will span a group of nearby buildings. In TCP/IP networking, a
LAN is often but not always implemented as a single IP subnet.

5. In addition to operating in a limited space, LANs are also typically owned,
controlled, and managed by a single person or organization. They also tend to
use certain connectivity technologies, primarily Ethernet and Token Ring.
WAN - Wide Area Network
As the term implies, a WAN spans a large physical distance. The Internet is the
largest WAN, spanning the Earth.
A WAN is a geographically-dispersed collection of LANs. A network device called
a router connects LANs to a WAN. In IP networking, the router maintains both a
LAN address and a WAN address.
A WAN differs from a LAN in several important ways. Most WANs (like the
Internet) are not owned by any one organization but rather exist under
collective or distributed ownership and management. WANs tend to use
technology like ATM, Frame Relay and X.25 for connectivity over the longer
distances.
Metropolitan Area Network
a network spanning a physical area larger than a LAN but smaller than a
WAN, such as a city. A MAN is typically owned an operated by a single entity
such as a government body or large corporation.
 ADVANTAGES AND DISADVANTAGES OF ROUTERS
Advantage of Router -
a) Router limits the collision domain.
b) Router can function on LAN & WAN>
c) Router can connects different media & architectures.
d) Router can dtermine best path/route for data to reach
the destination.
e) Router can filter the broadcasts.
Disadvantage of Router -
a) Router is more expensive than Hub, Bridge & Switch.
b) Router only waork with routable protocol.
c) Routing updates consume bandwidth.
d) Increase latency due to greater degree of packet
filtering.
 ADVANTAGES AND DISADVANTAGES OF BRIDGES
Advantages of Bridge:
· Simple bridges are inexpensive
· Simple configuration modes
· Isolate collision domains with micro-segmentation
· It increase network length

6. · Access control and network management capabilities
· Bandwidth scales as network grows
Disadvantages of Bridge:
· Does not limit the scope of broadcast
· Does not scale to extremely large networks
· Extremely large networks cannot rely on bridges
· Buffering and processing introduces delays
 ADVANTAGES AND DISADVANTAGES OF HUB
Advantage:
Hub is less expensive product.
it is used for connect the multiple devices.
Disadvantages:
It will broadcast to all the ports
It runs half duplex
If 10 Ports in a hub it will share bandwidth of 100 MbPs.
So each port share 10 Mbps
MODEM
A modem (modulator-demodulator) is a device that modulates an analog carrier signal to
encode digital information, and also demodulates such a carrier signal to decode the
transmitted information. The goal is to produce a signal that can be transmitted easily and
decoded to reproduce the original digital data. Modems can be used over any means of
transmitting analog signals, from light emitting diodes to radio. The most familiar example is
a voice band modem that turns the digital data of a personal computer into
modulatedelectrical signals in the voice frequency range of a telephone channel. These
signals can be transmitted over telephone lines and demodulated by another modem at the
receiver side to recover the digital data.
SUBNET
A subnetwork, or subnet, is a logically visible subdivision of an IP network.[1]
The practice of
dividing a network into two or more networks is calledsubnetting.
All computers that belong to a subnet are addressed with a common, identical, most-
significant bit-group in their IP address. This results in the logical division of an IP address
into two fields, a network or routing prefix and the rest field or host identifier. The rest field is
an identifier for a specific host or network interface.

7. Cisco Packet Tracer
Cisco Packet Tracer is a powerful network simulation program that allows students to
experiment with network behavior and ask “what if” questions. As an integral part of the
Networking Academy comprehensive learning experience, Packet Tracer provides
simulation, visualization, authoring, assessment, and collaboration capabilities and facilitates
the teaching and learning of complex technology concepts.
 Packet Tracer supplements physical equipment in the classroom by allowing
students to create a network with an almost unlimited number of devices,
encouraging practice, discovery, and troubleshooting. The simulation-based learning
environment helps students develop 21st century skills such as decision making,
creative and critical thinking, and problem solving. Packet Tracer complements the
Networking Academy curricula, allowing instructors to easily teach and demonstrate
complex technical concepts and networking systems design.
Packet Tracer features
The current version of Packet Tracer supports an array of simulatedApplication Layer
protocols, as well as basic routing with RIP, OSPF, and EIGRP, to the extent required by the
current CCNA curriculum. While Packet Tracer aims to provide a realistic simulation of
functional networks, the application itself utilizes only a small number of features found
within the actual hardware running a current Cisco IOS version. Thus, Packet Tracer is
unsuitable for modeling production networks. With the introduction of version 5.3, several
new features were added, including BGP. BGP is not part of the CCNA curriculum, but part
of the CCNP curriculum.
Packet Tracer
Cisco Packet Tracer 5.0 in Windows 7
Operating
system
Microsoft
Windows and Debian-
Like Linux