A computer network connects computers and devices together through communication devices and transmission media. It allows sharing of resources like printers, files, data and information. There are three main types of networks - local area networks (LANs) within a small geographical area, metropolitan area networks (MANs) within a city, and wide area networks (WANs) across large areas like countries. Network architecture refers to the overall design of a computer network and describes how it is configured and what strategies are used. The two main architectures are client/server, where a server provides services to clients, and peer-to-peer where all computers have equal capabilities without a central server.

1. CHAPTER 3: COMPUTER
NETWORKS AND
COMMUNICATIONS
Basic Concepts of Computer Networks

2. Definition of Computer Networks
A computer network is a Devices – printer,
scanner
collection of computers
Communication devices
and devices NIC Router
connected together via Hub ??
??
communication devices
Transmission Media
and transmission media.
For examples it may
Physical
connect computers,
Infrared
printers and scanners. Radiowave
Satellite

4. Definition of Communication
Communication describes a process in which two or
more computer or devices transfer data, instructions
and information.

5. The Importance/Advantage of
Computer Networks
s Sharing of devices such as printer and scanner
a Sharing of program/software
a Sharing of files
, Sharing of data
a Sharing of information
, Sharing of single high-speed internet connection
d Can access server centered database
B Better communication using internet services such
as email, mailing list and Internet Relat Chat (IRC)

7. Types of Computer Networks
A local area network is a network that connects
Local Area Network (LAN) computers and device in a limited geographical area
such as a home, school computer laboratory, office
building

8. A metropolitan area network (MAN) is a high speed
Metropolitan Area network that connects local area networks in a
Network (MAN) metropolitan area such as city or town and handles bulk
of communication activity across the region
A MAN typically includes one or more LAN but covers a
smaller geographic area than a WAN

9. A wide area network is a network that covers a large
Wide Area Network geographical area such country or the world
(WAN)
WAN combines many types of media such as telephone
lines, cables and radio wave. A WAN can be one large
network or can consist of two or more LANs connected
together
The internet is the worlds largest WAN

10. Differentiate between the types of
Computer Networks
Different LAN MAN WAN
Cost Low optic High Higher
Network Size Small Larger Largest
Speed Fastest Slower Slowest
Transmission Twisted-pair Twisted-pair Fiber optic
Media Fibre-optic cables Radio wave
Satellite
Number of Smallest Large Largest
Computers

11. Network Architecture
 Network architecture is the overall design of a computer
network that describes how a computer network is configured
and what strategies are being used.
 It is mainly focuses on the function of the networks.
 It is also known as network model or network design.
 Two main network architecture:

12. A server is a computer
that provides services
to clients and controls
access to hardware,
software and other
resources
A client is a computer
that request services
from a server computer

13. On a client/server network, one computer act as a server
Client/Server that provides services and the other computers (client) on
the network request services from the server.
A server is a computer that controls access to the
hardware, software and other resources on the network
and provides a centralized storage area for program.
A client is a computer that request services from a server
computer.
Peer-to-peer is a simple, inexpensive network that
Peer-to-Peer typically connects fewer than 10 computers. All computers
in the network have equal capabilities to use the resources
(hardware, software, data and file) available on the
network. With peer-to-peer networks, there is no central
server.

14. The Differences between Client/Server
and Peer-to-Peer
Client/Server Peer-to-Peer
1) Server has to control ability 1) All computers have equal
while client’s don’t ability
2) Higher cabling cost 2) Cheaper cabling cost
3) It is used in small and large 3) Normally used in small
networks networks with less than 10
4) Easy to manage computers
5) Install software only in the 4) Hard to manage
server while the clients share 5) Install software to every
the software computer
6) One powerful computer 6) No server is needed
acting as server