Bab3-computer network

CHAPTER 3

COMPUTER NETWORK AND
COMMUNICATIONS

Basic concepts of computer networks
and communications
Define computer networks
 is a system of interconnected computers and
peripheral devices.
 For example, it may connect
computers, printers, scanners and cameras

Define computer communications
 is about the transfer of information from a
sender, across a distance, to a receiver.
 Using electricity, radio waves or
light, information and data in the form of codes
are transmitted through a physical medium such
as wire, cable, or even the atmosphere.
 The information that is transmitted (sent) can be
text, voice, sound, video, graphics and
images, or a combination of all these, which we
call multimedia.

Online
education

The importance
of computer E-
E-business banking
networks and
communications

Long Distance
communications

Online education
 With a network connections, online education is made
possible. Students at any location around the world can
participate in an online classroom, download tutorial
questions and submit their assignments.

E-business
 Is refers to conducting business transactions on the
internet, not only limited to buying and selling but
also servicing customers and collaborating with
business partners.

E-banking
 handles all types of banking transactions like
account management, fund transfer and payments
primarily over the internet.

Long Distance communications
 is made easy via network availability.
 Communication is possible via voice, text or video.

Types of computer network

Local Area
network
(LAN)
Metropolitan Area
Network
(MAN)
Wide Area Network
(WAN)

Metropolitan Area Network (MAN)
 can be defined as a group of computers and
network devices connected together within a large
physical area.
 WANis the largest network of all network types.
 The Internet is the largest WAN in the world.
 WAN generally covers large distances such as
states, countries or continents.

Local Area network (LAN)
 is a group of computers and network devices
connected together, usually within the same building.
 It is the smallest network compared to the other two
networks.
 The simplest form of LAN is to connect two
computers together.
 Inexpensive hardware used in LAN previously
include twisted pair, coaxial cables and the higher
end is fiber optic or wireless

Wide Area Network (WAN)
o WAN is a group of MANs or LANs or the mixture of both networks.

o WANis the largest network of all network types. The Internet is the largest WAN
in the world.

o WAN generally covers large distances such as states, countries or continents.

o A device called a router is needed to connect the MANs and LANs all over a large
physical area.
o A router is a special networking device that connects two or more different
networks and keeps data flowing between them.

Types Network Architecture

Client
/Server Peer- to -
peer

Client/server
 is a network in which the shared files and applications are
stored in the server but network users (clients) can still
store files on their individual PCs.

Peer-to-peer
 a network with all the nodes acting as both servers and
clients. A PC can access files located on another PC and
can also provide files to other PCs.

3 types of network topology

Bus topology

Ring topology

Star topology

Bus topology
 consists of a single central cable to which all computers
and other devices connect

Ring topology
 consists of all computers and other devices that are
connected in a loop
Star topology
consists of a central host which acts as the centre, and all
nodes connect to the host.

Types of network communications
technology

internet extranet intranet

Internet
 is the worldwide, publicly accessible system of interconnected
computer networks that transmit data by packet switching using
the standard Internet Protocol (IP).

Extranet
 is a private network that uses Internet protocols, network
connectivity, and possibly the public telecommunication system
to securely share part of a business’s information or operations
with suppliers, vendors, partners, customers or other businesses.
Intranet
 is an internal network that uses Internet technologies and it is a
small version of the Internet that exists within an organisation.

Devices needed in computer
communications network

Network Wireless Modem
interface Card Network (internal and
(NIC) Interface Card external)

Hub /switch Router

Functions

Network interface Card (NIC)
 is an adapter card or PC card that enables the computer
to access the network
Wireless Network Interface Card
 is a network card that provides wireless data
transmission
Modem (internal and external)
 There are two types of modem, internal modem and
external modem. An internal modem only works in
stand-alone computers.

Hub /switch
 is a common connection point for devices in a network.
 Hubs are commonly used to connect segments of a LAN.
Router
 is a communications device that connects multiple
computers or other routers together and transmits data
to the correct destination

Medium
Types of Cables

Unshielded Shielded
Twisted Twisted
Pair Pair
(UTP) (STP)

Fibre Optic
Cable

Bab3-computer network

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