BASIC_COMPUTER_NETWORKING (1).pdf

BASIC COMPUTER NETWORKING
BY PROFESSOR MBAIWA
COMPSYS (Pvt) Ltd

Outline
 Computer network or distributed system
 Types of networks
 Internet
 Why are networks useful ?
 Client/server and peer-to-peer models
 telephone networking in computing
 TCP / IP

INFORMATION NETWORKS
 Networking is an important
aspect of the modern computer
environment, allowing people
and companies to communicate
and share resources quickly and
cost-efficiently.

In order for computers to communicate
with each other and share resources,
they must be connected together.

Networks and the Internet
A network is a collection of computers and devices
connected together, either by wire cables, fibre optic
cables, microwave links or satellite. (communications
devices and transmission media )
 Collection of autonomous interconnected computers.
 Example : computers in a company
 Internet is not exactly a computer network but a network of networks.

_1) LAN
A LAN (Local Area Network) is a netwok system
whereby individual PCs are connected together within
a relatively limited area such as a building, university
campus, company or organization

BASIC_COMPUTER_NETWORKING (1).pdf

2) WAN
 A WAN (Wide Area Network) as the name implies a
computer network that covers a large geographical
area, allows you to connect to other computers over
wider area (i.e. the whole world).
 It can also be called a connection of so many Local A
Networks from different lacations, towns, cities and
countries.

THE INTRANET AND EXTRANET
INTRANET
 An intranet is a network designed for information
processing within a company or organization and is
accessible only by that organisation‟s members.
It enables you to use such services as document
distribution, software distribution, access to databases,
and training. You can also access applications
associated with the Internet, such as Web pages, Web
browsers, FTP sites, e-mail, newsgroups, and mailing lists.
It enables two or more branches of the same company
to share information via the internet, eg banks

AN EXTRANET
is an extension of your corporate intranet. However, an
extranet lets your customers, for example, have access to
your products or databases from outside the company.
They can do this by using the World Wide Web, and by
logging on with a user name and password. For example
e-banking, a customer can request his bank balance and
make payments from his account at home

THE INTERNET
 Internet is short for internetwork, and as such is any set of
interconnected networks that are linked together to
exchange data and distribute processing tasks.
The Internet is a public, cooperative, and self-sustaining
facility accessible to hundreds of millions of people
worldwide. Physically, the Internet uses a portion of the
total resources of the currently existing public
telecommunications networks. The two most popular uses
of the Internet are e-mail and surfing the World Wide Web
and e-commerce

World Wide Web:
A computer network system that allows users to browse
through information available on computers round the world.
It is more like a book with billions of pages which anyone can
read and write on.
The World Wide Web opened the Internet to millions of people
interested in finding information. There are over one million
Web sites around the world and the number is growing very
quickly.
The World Wide Web consists of documents called Web
pages that contain information on a particular topic. A Web
page might also contain one or more links that point to other
Web pages.

Using the Web, you have access to millions of pages of
information. Web surfing is done with a Web browser,
eg Firefox, chrome etc
Once you have accessed the Web using a browser, you
can use a search engine, to help you find particular sites.
Search engines are graphic interfaces that you can use to
search for a site using its Web address, or a keyword.
The Internet provides online users access to a practically
unlimited amount of information via the World Wide Web,
and allows users to contact one another cheaply and
easily

USES OF NETWORK / ADVANTAGES
 If ten people are working together within an office it makes sense for them
all to be connected. In this way the office can have a single printer. Even
more useful is the ability to share information when connected to a network.
 Cost effective in terms of stationery
 •
communicate with one another as well as others outside the organisation,
normally through the use of electronic messages
 •
access information and services supported on the World Wide Web •
share
documents and data
 •
support various work processes in the organisation based on the
automation of specific tasks.
 Faster,
 Flexible, informarion can be accessed from a remote location
 E-commerce, allows people to conduct business online

Client/server and peer-to-peer models
 A computer that is not connected to a network is referred to as a
stand-alone computer.
 When a computer is physically connected to a local area network,
using a cable or other communications channel, the computer
becomes a workstation on the network. Each device on the
network including workstations, servers, and printers is referred to
as a node.
Node: A processing location on a network.

Network server:
 A computer that is connected to the network and that ‘serves’ or
distributes resources to network users.
 Usually the server is a higher than average performance computer. The
server also controls the network access of the other computers which are
referred to as the 'client' computers or terminals.
 Networks use different kinds of servers to carry out specialized functions.
File server: A computer that serves or distributes application programs
and data files to workstations within a computer network. The hard drive
of the file server is shared by the workstations on the network.
 Any user on the network can store files on the server. Other types
of servers include a print server to manage one or more printers
and a database server to process database queries.

Client:
 A client is a common computer used to access remote data.
 The client sends a request over the network to the server.
 The server gets the request, does the job and sends back a reply.
 Example : access a page on the Web
 Server : remote Web server
 Client : Web browser

WHATS NEEDED
 Protocol
 A common language or protocol (TCP/IP /APPLE TALK) is a convention or
standard that controls or enables the connection, communication, and
data transfer between two computing endpoints. Sending and receiving
systems need to use the same protocol unless a gateway service sits
between networks and translates from one to the other.
Internet Protocol
 An IP number (also called IP address) identifies a machine on the network.
 A machine may host several applications. Each application is accessible
via a communication port.
 To send data to an application running on a specific machine, the IP
number and the application port number are required.

Cont …………………..
Router or Switch /Hub
 A router is a computer networking device that forwards data packets across
a network toward their destinations, through a process known as routing. A
router acts as a junction between two or more networks to transfer data
packets among them. A router is different from a switch.
 A switch connects devices to form a Local area network (LAN).
 A „Switch‟ used to switch the data from one point to another. Hubs are
outdated and are little used for new installations.

Cont …………………..
 You will also need network cables crimped with the RJ 45
connectors on both ends
RJ 45 Connector
Network Cable
 Lastly 2 or more computers that has an operating system which supports
networking

Server
Hub/Switch/ router
Client / terminal
Client / terminal
Client / terminal
Network Cable

DUMB TERMINAL AND INTELLIGENT TERMINAL
 An intelligent terminal is a client that has a processing capacity and
can do other processes independent of the server. It has its own
processor and memory, it only needs the server to access
information or resources that are shared by the server.
 Examples of intelligent terminals are the ones on the above diagram

 A dumb terminal is the complete opposite of an intelligent terminal, it
does not have processing capacity so it depends entirely on the server,
it does not have any memory,
 It consist of a monitor, keyboard and a mouse

PEER TO PEER NETWORK
 Every person can communicate with one or more other people.
 Commonly implemented where few computers are connected and where
security is not necessary. Peer-to-peer networks simply link a number of
PCs together with no network server. This is a cheaper and easy way of
networking All computers have the same status, hence the term 'peer',
and they communicate with each other on an equal footing. Files, can be
shared across the network and all the computers on the network can
share devices, such as printers or scanners, which are connected to any
one computer.
 A type of network in which each workstation has equivalent capabilities
and responsibilities.

 The term 'wireless network' refers to two or more computers communicating
using standard network rules or protocols, but without the use of cabling to
connect the computers together. Instead, the computers use wireless radio
signals to send information from one to the other.
 Wireless Access Point (WAP) A wireless access point (AP) is similar to an
Ethernet hub, but instead of relaying LAN data only to other LAN stations, an
access point can relay wireless data to all other compatible wireless
devices as well as to a single (usually) connected LAN device, in most
cases an Ethernet hub or switch, allowing wireless devices to communicate
with any other device on the LAN.
 A wireless router integrates a wireless access point with an Ethernet switch
and an Ethernet router. The integrated switch connects the integrated
access point and the integrated Ethernet router internally, and allows for
external wired Ethernet LAN devices to be connected as well as a (usually)
single WAN device such as a cable modem or DSL modem.
WIRELESS NETWORK

 Telephone technology, or telephony, is used in the modern computer
environment to connect computers.
 His is the use of telephone networks to interconnect computers and other
devices that work with computer coded data, so that data can be
transferred from one location to another
 For computers to be able to communicate via the telephone system
another device is needed which understand both the telephone
language and the computer language. This device is known as the
Modem

 A modem is a piece of hardware that allows computers to communicate
using telephone lines. A modem converts outgoing digital signals from a
computer or other digital device to analog signals.
 These analog signals can travel over a conventional telephone line to the
required destination. The receiving modem converts the incoming analog
signal to a digital signal for the receiving computer.
MODEM
(Modulator Demodulator)

 The PSTN operates using analog technology. Analog technology is based on
a signal that is continuously varying in strength or quantity, such as voltage.
Digital technology is based on discrete units, expressed as the binary digits 1
and 0.
 This is an example of a packet-switched network,
 The computer will be connected to the telephone line, this is usually called
Dial-up connection, and the speed is rather too slow and the major
disadvantage is that if you are connecting on internet you will not be able to
use the telephone services and vice- versa unless you have a second line.
PUBLIC SWITCHED TELEPHONE NETWORK

 ISDN is similar to PSTN except that it is a digital technology at higher data
rates with a much lower connection time. It also offers multiple channels.
 This is a technology of transmission that combines data, voice and video
signal meaning that people can talk on the telephone and also send data
between their computers, they can transit data much faster than a PSTN
and their transmission are more error free than ordinary telephone lines.
INTERGRATED SERVICE DIGITAL NETWORK

 ADSL stands for asymmetric digital subscriber line. ADSL offers you the
economical means of substantially increasing bandwidth in residences and
small offices. With ADSL, you can use the telephone and PC simultaneously
without a second line.
 This means that when you log on to the Internet, your telephone line will not be
engaged. Moreover, because you‟re transferring data back and forth at
higher rates, you‟ll notice the difference when you play interactive games,
work remotely, or have a video conference
 ADSL offers you speed and convenience. ADSL saves you time by giving faster
downloads and uploads. This means that you can send and receive larger files
and graphics at a faster rate without the worries of information bottlenecks that
may happen when you‟re accessing information at slower transfer rates.
 ADSL‟s connectivity is always in real-time because it‟s “always on,” and this
lets you receive data while you‟re away from your desk.
ASYMMETRIC DIGITAL SUBSCRIBER LINE

 Networking is an important aspect of the modern computer environment,
allowing people and companies to communicate and share resources
quickly and cost-efficiently.
 Every person can communicate with one or more other people. You just need
the right resources

BASIC_COMPUTER_NETWORKING (1).pdf

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