• A computer network or data network is

a telecommunications network that

allows computers to exchange data.

• In computer networks, networked computing

devices pass data to each other along data

connections.

• Data is transferred in the form of packets. The

connections (network links) between nodes are

established using either cable media or wireless

media.

• The best-known computer network is the Internet.

Computer Networking

Making devices talk to each other for the

purposes of communication is nothing new. Early

forays into telephony such as the telegraph and

telephone have since evolved

into more complicated devices, and now a

computer can be networked to the Internet, another

PC, or even a home stereo.

In the early 1960s, individual computers had

to be physically shared, making the sharing of data

and other information difficult. Seeing this was

impractical, researchers developed a way to

“connect” the computers so they could share their

resources more efficiently. Hence, the early

computer network was born.

Brief History of Networking

• 1961: Kleinrock - queuing theory showseffectiveness of packet-switching

• 1964: Baran - packet-switching in militaryapplications for survivable networks

• 1967: ARPAnet conceived by Advanced ResearchProjects Agency

History: Networking

• 1969: First ARPAnet node operational

–Prof.Kleinrock sends a message across fromUCLA to Stanford

• 1972:

–ARPAnet demonstrated publicly

–NCP (Network Control Protocol) first host-hostprotocol

–First e-mail program

–ARPAnet has 15 nodes

History: Networking

• Time sharing became difficult since different machineshad different operating systems, versions and programs–however, these led to development of Internet

• Vinton Cerf. Bob Kahn, Bob Braden and Jon Pesteldeveloped TCP/IP

• Cerf and Kahn’s internetworking principles:

– minimalism, autonomy - no internal changes requiredto interconnect networks

– best effort service model

– stateless routers

– decentralized control define today’s Internetarchitecture

History: Networking

• 1978: TCP/IP v4 was released

– Aimed to interconnect different kinds of networks

• 1979: ARPAnet has 200 nodes

• 1983: deployment of TCP/IP in ARPAnet

• 1983: SMTP e-mail protocol defined

• 1983: DNS defined for name-to-IP-address

translation

• 1985: FTP protocol defined

• 1988: TCP congestion control

100,000 hosts connected to confederation of networks

History: Networking

• 1970: ALOHAnet satellite network in Hawaii

(CSMA developed), later connects to ARPANet

• 1973: Bob Metcalfe’s PhD thesis proposes

Ethernet (CSMA/CD developed)

• 1974: Cerf and Kahn - architecture for

interconnecting networks: the word “Internet”

makes its appearance from Cerf’s writings

History: Networking

• Early 1990’s: ARPAnet decommissioned

• Early 1990s: WWW

– Hypertext (1945 Bush: “As We May Think” article, TedNelson, Engelbert, Andries in 1968 )

– HTTP: Tim Berners-Lee develops WWW an Internet basedhypermedia initiative at CERN, specifies URLs, HTTP andHTML which became basis for today’s WWW

– 1994: Mosaic (Univ. of Illinois), later Netscape the majorbrowsers until late 1990’s

– late 1990’s: commercialization of the WWW, with introductionof HTTPS e-commerce is realized

Late 1990’s:

• est. 50 million computers on Internet

• est. 100 million+ users

• backbone links running at 1 Gbps

History: Networking

• Worldwide collection of networks,

gateways, servers and computers using a

common set of telecommunication

protocols to link them together.

• It is a system connecting millions of

computers around the world. Which also

known as information super highway.

What is Internet?

1960’sUS government seeks nuclear war proof communications, briefs project to ARPA

1969 Universities and researches connected to ARPAnet

1977 ARPAnet engineers realize the network is going to

grow beyond expectations

1983 ARPAnet switched to TCP/IP

1989Tim Berners-Lee proposes a new set of Internet

protocols

1995 US government releases Internet

for commercial use

Ethical rules for Computer Users

Some of the rules that individuals should

follow while using a computer are listed

below:

o Do not use computers to harm other

users

o Do not use computers to steal others

information

o Do not access files without the

permission of the owner

o Do not copy copyrighted software

without the author’s permission.

o Always respect copyright laws and

policies.

o Complain about illegal communication and activities,

if found, to Internet service Providers and local law

enforcement authorities

o Users are responsible for safeguarding their User ID

and Passwords. They should not write them on

paper or anywhere else for remembrance

o Users should not intentionally use the computers to

retrieve or modify the information of others, which

may include password information, files, etc..

o Respect the privacy of others, just as you expect

the same from others

o Do not use other user's computer resources

without their permission

o Use Internet ethically

Internet Ethics

Internet Ethics - means acceptable behavior for

using internet. We should be honest, respect the

rights and property of others on the internet.

Acceptance

One has to accept that Internet is not a value free-zone .It means World Wide Web is a place where valuesare considered in the broadest sense so we musttake care while shaping content and services and weshould recognize that internet is not apart from universalsociety but it is a primary component of it.

Sensitivity to National and Local CulturesIt belongs to all and there is no barrier of national

and local cultures. It cannot be subject to one set ofvalues like the local TV channel or the localnewspaper We have to accommodate multiplicity ofusage.

While using e-Mail and chattingInternet must be used for communication with familyand friends. Avoid chatting with strangers andforwarding e-mails from unknown people /strangers. Andwe must teach children about risks involved in chattingand forwarding e-mails to strangers.

Pretending to be someone elseWe must not use internet to fool others by pretendingto be someone else. Hiding our own identity to foolothers in the Internet world is a crime and may also be arisk to others. It’s our responsibility to teachchildren the same.

Avoid Bad languageWe must not use rude or bad language while using e-mail, chatting, blogging and social networking, We needto respect their views and should not criticize anyoneon the internet and the same should be taught tochildren.

Hide personal informationWe should teach children not to give personal details

like home address, phone numbers, interests, passwords. Nophotographs should be sent to strangers and they should beasked to hide their personal details from strangers because itmight be misused and shared with others without theirknowledge.

While DownloadingInternet is used to listen and learn about music , It is also

used to watch videos and play games We must not use itto download them or share copyrighted material. The sameshould be taught to children, and they must be aware of theimportance of copyrights and issues of copyright.

SupervisionYou should know what children are doing on the

internet and the sites they visit on the internet andshould check with whom they are communicating.Restrict them browsing inappropriate sites. Parentalinvolvement is essential when a child is using theinternet in order to make him follow the rules.

Encourage children to use InternetWe must encourage children, students and

others to gain the knowledge from the internet and useit wisely. Internet is a great tool where we can gatherinformation which can be used for learning.

Access to InternetThe internet is a time-efficient tool for everyone that

enlarges the possibilities for curriculum growth.Learning depends on the ability to find relevant and

reliable information quickly and easily, and to select, understandand assess that information. Searching for information on theinternet can help to develop these skills.

Classroom exercises and take-home assessment tasks,where students are required to compare website content, areideal for alerting students to the requirements of writing fordifferent audiences, the purpose of particular content,identifying and judging accuracy and reliability.

Since many sites adopt particular views about issues, theinternet is a useful tool for developing the skills of distinguishingfact from opinion and exploring subjectivity and objectivity.

Internet, Intranet and

Extranets

What is Internet ?

• It is a Global network of computers, (servers or clients).to exchange information.

• It is a "network of networks" that includes millions ofprivate and public, academic, business, and governmentnetworks (local or Global),

linked by copper wires, wireless connections, and othertechnologies.

Hardware and Software of Internet

Variety of hardware and software are used to make

Internet functional.

• Modem

Device that enables computers to communicatethrough phone lines.

When we start internet the our modem communicatesto modem of ISP.

• Computer

In addition to a modem, you need a client capable ofhandling multiple data types.

• Software

Two types of software’s required to enable your PC as anInternet PC.

• Communication software to establish connection

• Client software for browsing, e-mail, news.

these software’s are provided with windows itself.

Continued…

Applications Of Internet

• Download programs and files

• E-Mail

• Voice and Video Conferencing

• E-Commerce

• File Sharing

• Information browsing

• Search the web addresses for access through search engine

• Chatting and many more…

Disadvantages of Internet

• Theft of personal information such as name, address, credit cardnumber etc.

• Virus threats nothing but a program which disrupts the normalfunctioning of your system.

• Spamming refers to receiving unwanted e-mails in bulk, whichprovide no purpose and needlessly obstruct the entire system.

• Pornography This is perhaps the biggest threat related to children’shealthy mental life. A very serious issue concerning the Internet.

Though, internet can also create havoc, destruction andits misuse can be very fatal,the advantages of it outweigh its disadvantages.

Intranet

What is Intranet ?

• Internal company network that uses Internet standards(HTML, HTTP & TCP/IP protocols) & software.

• Accessed only by authorized persons, especially members oremployees of the organization

Intranet Security

Two levels of Security required:

• Internal

It can be imposed by Public Key Security & Encryption Key.

• External

Through Firewall.

What is Firewall ?

• Security device located between firm’s internal network(intranet) & external network (internet).

• Regulates access into & out of a company’s network based ona set of rules.

Note : needs to be upgraded from time to time to check latest potentialsecurity problems.

Applications of Intranet

• Sharing of company policies/rules & regulations

• Access employee database

• Distribution of circulars/Office Orders

• Access product & customer data

• Sharing of information of common interest

• Launching of personal/departmental home pages

• Submission of reports

• Corporate telephone directories

Disadvantages

Information overload lowers productivity

True purpose of the Intranet is unknown to many employees/departments

Hidden or unknown complexity and costs

Productivity

problem

Unauthorized access

Abuse of access

Denial of service

Security

problem

A company may not have person to update their

Fear of sharing information and the loss of control

Limited bandwidth for the business

Management

problem Intranet on a routine basis

Extranet

What is Extranet ?

• Extranet is an Intranet for outside authorized users usingsame internet technology.

• Inter-organizational information system.

• Enable outsiders to work together with company’semployees.

• Open to selected suppliers, customers & other businesspartners

Examples..

• Dealers/distributors have access to product files such as :-

1. product specification,

2. pictures,

3. images, etc.

to answer the queries of the customer.

Benefits of Extranet

• Improved quality.

• lower travel costs.

• lower administrative & other overhead costs.

• reduction in paperwork.

• delivery of accurate information on time.

• improved customer service.

• better communication.

• overall improvement in businesseffectiveness.

Disadvantages

• The suppliers & customer who don’thave technical knowledge feel problem.

• Faceless contact.

• Information can be misused by other competitors.

• Fraud may be possible.

• Technical Employees are required.

Clients, partners, customers

Layered System View

Intranet

Extranet

Internet

Corporate members

Global society: competitors

THE END

Thank You