2. History and Overview of Networks
Each of the past three centuries was
dominated by a single new technology.
The 18th century was the era of the Industrial
Revolution.
The 19th century was the age of the steam
engine.
3. The 20th century, the key technology was information
gathering, processing, and distribution.
Among other developments, we saw
The installation of worldwide Telephone networks,
The invention of radio and television,
The birth and unprecedented growth of the computer
industry,
The launching of communication satellites, and, of
course, the Internet.
4. What is a Network?
A network consists of two or more computing
systems connected together, and they can
communicate and share resources (e.g.
information)
5. Applications of Computer Networks
Computer systems and peripherals are connected
to form a network. They provide numerous
advantages:
Resource and Information sharing.
Centralized administration
Communication using emails over internet.
Access to remote information.
Video conferences
Electronic commerce(e.g. Amazon,ebay).
Interactive entertainments(e.g. Netflix).
6.
7. Disadvantages of computer network
Security issues
-Computer hackers can get access to our system
using different tools.
-Hackers are someone who break our system
and have unauthorized access.
Virus attack vulnerability increase
Expensive setup cost
– Cost of hardware and technician
Dependency on the main server(single point of
failure)
8. How many kinds of networks?
Depending on different perspectives , we can
classify networks in different ways:
Based on network size/Geo-area coverage
(LAN,MAN & WAN)
Based on management method/functionality
(peer-to-peer & client-server)
Based on physical layout/shape/topology
(bus, star, ring, mesh etc)
9. Network Architectures
A communication network can be categorized
into two broad models depending upon its
architecture.
1. Peer-to-peer network model
2. Client-Server network model
10. Peer-to-peer architecture
In a p2p network, all computers on the
network are considered equal, with
each workstation offering access to
resources and data(e.g Bluetooth
connection).
11. Client-Server architecture
The client-server model structure is a
centralized network in which the server hosts,
provides, and maintains the majority of the
client’s data and services(e.g Database server
for SMIS).
12. Servers
A server commonly has multiple processors, large
hard drives, and large amounts of RAM.
A server provides centralized management of
resources, security, and expanded access to
networked resources in a network.
Two types
Non-dedicated – provides many different services
to its client computers such as file retrieval,
printing, and emailing.
Dedicated – provides only one type of resource to
its clients, such as printing.
14. Other network components
Shared peripherals – a device that is connected
to a computer and controlled by its
microprocessor(e. g printers)
Media – physical pieces used to transport data
from one computer to another computer or
peripheral on the network(e.g. network cables).
Data – packets
16. Transmission Medium
On basis of physical medium, there are 2
types of networks:
(a) Wired Network and
(b) Wireless Network
17. Wired Network
“Wired” as the name suggests refers to
any physical medium connected through
wires and cables.
The wires/cables can be copper wire,
twisted pair or even fiber optic.
Wired connectivity is responsible for
providing high security with high
bandwidth provisioned for each user.
18. Benefits of wired network
Greater speed
Higher resistance to noise
Highly reliable
Greater security
19. Wireless Network
“Wireless” as the term refers, uses air as
a medium to send electromagnetic
waves or infrared waves.
Wireless devices have antennas for
communication.
Wireless becomes more useful in areas
where wires can’t be reached. E.g. Wi-Fi,
Bluetooth, etc.
20. Benefits of wireless network
Greater mobility
No difficulty of network cables
Best for mobile devices
Easy installation and management
