Internet Tutorial.01

8/3/2019 Internet Tutorial.01

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New Perspectives on the Internet, 5eTutorial 1

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Introduction to the Internet and the

World Wide Web

History, Structure, andGetting Connected

Tutorial 1


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Objectives

Obtain an overview of the information andtools that are available on the Internet

Learn what computer networks and internetsare and how they work

Find out how the Internet and the World WideWeb began and grew

Compare different methods for connecting tothe Internet


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Internet and World Wide Web:Amazing Developments

The Internet is a large collection of computers all overthe world connected to one another.

One of the most amazing technological developmentsof the 20th century.

The World Wide Web is a subset of computers on the

Internet that has helped make Internet resourcesavailable to people who are not computer experts.


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New Ways to Communicate

E-mail

Electronic discussions

Instant messaging

Information Resources and Software

Newspapers & magazines

Government documents

Research reports & books

Software download sites


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Doing Business Online

Electronic storefronts

Coordinate worldwide operations

Recruit employees

Entertainment

Review restaurants, movies, theater, musical

events and books.

Interactive games

Follow sports teams


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Computer Networks

Network Interface Card (NIC): a card used to connecta computer to a network of other computers.

Server: computer that accepts requests and sharessome or all of its resources with computers it isconnected to.


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Client/Server Local Area Networks

Server: runs software that coordinates informationflow among other computers.

Client: computers connected to a server.

Network Operating System: software that runs on aserver.

Client/Server Networks: one server computersharing its resources with multiple client computers.

Local Area Network (LAN): network of computerslocated close to each other.


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Client/Server LAN


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Client/Server Local Area Networks

Node or network node: each computer,printer, or other device connected to a

network.

Minicomputer and mainframe computer:larger, more expensive computers used by

businesses and organizations to processlarge amounts of work.


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Connecting Computersto a Network Types of Cable

Twisted Pair: oldest type, used by telephone companies,usually Category 1.

CoaxialCable: 20 times faster than Category 1, moreexpensive

Category5: carries signals between 10 & 100 timesfaster than coaxial cable, easy to install.

Fiber-opticcable: most expensive, transmits pulsingbeams of light through very thin strands of glass, fastesttransmission rate.


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Types of Cable


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TWISTED-PAIR

COAXIAL

FIBER-OPTIC


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Connecting Computersto a Network Wireless Networks

Becoming more common as costs continue to drop.

Welcome in organizations that occupy old buildings.

Popular with companies whose employees uselaptop computers.

Used by schools in classrooms, libraries, and studylounges.

Used in homes.


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Wireless Home Network



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Wide Area Networks

WAN: a network of networks or an internet.

Internet: a worldwide collection ofinterconnected networks; owners havevoluntarily agreed to share resources andnetwork connections.


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Origins of the Internet

Early 1960s by the U.S. Department of Defense (DOD).

Major research project authorized as a part of national

security.

Explored ways to connect large mainframe computers andweapons installations distributed all over the world.

Defense Advanced Research Projects Agency (DARPA)charged with the task


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Connectivity: Circuit Switchingvs Packet Switching

Circuit switching:

centrally controlled

single-connection method

used by most local telephone traffic today

Vulnerable to destruction of signal control

point or any link in the single path that carriesthe signal.


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Packet-switching: files and messages broken downinto packets and labeled electronically with codes fortheir origin and destination.

Packets travel from computer to computer along thenetwork until they reach their destination.

Routers determine the best way for a packet to movetowards its destination.


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Routers use routing algorithms programs todetermine best path for packets.

Packet-switched networks more reliable:

rely on multiple routers instead of central point ofcontrol.

each router can send individual packets along different

paths if parts of the network are not operating.


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Origins of the Internet

DARPA researchers connected first computer switchesin 1969.

ARPANET grew over next three years to include over20 computers.

Computers communicated to other computers on thenetwork by using NetworkControlProtocol (NCP).

Protocol: collection of rules for formatting, ordering,and error-checking data sent across a network.


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Open Architecture Philosophy

Four Key Points:

Independent networks should not require any internalchanges to be connected to the Internet.

Packets that do not arrive at their destinations mustbe retransmitted from their source network.

The router computers do not retain information aboutthe packets they handle.

No global control will exist over the network.


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New set of protocols developed in 1970 by VincentCerf and Robert Kahn:

Transmission Control Protocol

Internet Protocol

(TCP/IP)

TCP: rules used by computers on a network to

establish and break connections.

IP: rules for routing of individual data packets.


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TCP/IP used today in LANs and on the Internet.

Term Internet first used in a 1974 article about theTCP protocol written by Cerf and Kahn.

Vincent Cerf considered to be the father of theInternet by many.


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Birth of E-Mail:A New Use for Networks

Ray Tomlinson, an ARPANET researcher, wrote aprogram that could send and receive messages overthe network in 1972.

E-mail was born and rapidly became widely used inthe computer research community.

ARPANET continued to develop faster and moreeffective network technologies.

Began sending packets by satellite in 1976.


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More New Uses forNetworks Emerge

File Transfer Protocol (FTP) - transfer files betweencomputers.

Telnet - users log in to their computer accounts fromremote sites.

Mailing lists (LISTSERV), information posting areas

(Usenet), and adventure games among newapplications appearing on the ARPANET.


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Interconnecting the Networks


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Commercial Interest Increases

National Science Foundation (NSF) prohibitedcommercial network traffic on networks it funded.

Businesses turned to commercial e-mail services.

Larger firms built TCP/IP-based WANs that used leasedtelephone lines to connect field offices to corporateheadquarters.

NSF permitted two commercial e-mail services, MCIMail and CompuServe, to establish limited connectionsto the Internet in 1989.


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Intranet: LANs or WANs that use TCP/IP protocolbut do not connect to sites outside the firm.

Extranet: an intranet that allows selected outsideparties to connect.

Internet Engineering Task Force (IETF): a self-organized group that makes technical contributions tothe engineering of the Internet and its technologies.

ARPANET grew from 4 computers in 1969 to over300,000 by 1990.

Commercial Interest Increases


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Growth of the Internet

Formal definition of Internetwas adopted in 1995 by theFederal Networking Council(FNC).


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From Research Project toInformation Infrastructure


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Growth in number of Internet hosts


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Growth of the Internet

Number of hosts connected to Internet includes onlycomputers directly connected to the Internet.

Internet traffic now carries more files that containgraphics, sound, and video, so Internet files havebecome larger.


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New Perspectives on the Internet, 5eTutorial 1 31

New Structure for the Internet

Organized around four network access points(NAPs), operated by four different tele-communications companies.

The four companies and their successors sell accessto the Internet through their NAPs to organizationsand businesses.

The NSFnet still exists for government and researchuse.


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More than 180 million connected host computers andmore than 700 million worldwide Internet users.

TCP/IP numbering system that identifies users on theInternet is running short of numbers.

IP version 4 provides a maximum of about 4 billionaddresses.

IP version 6 approved in 1997 by the IETF allows existingusers to continue accessing the Internet while new system isbeing implemented.


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The Internet has become one of the most amazingtechnological and social accomplishments of thecentury.

Computers linked to this interconnected network arelocated in almost every country of the world.

Billions of dollars change hands every year over theInternet.


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World Wide Web

World Wide Web: a way of thinking aboutinformation storage and retrieval.

Web: software that runs on some of the computersconnected to each other through the Internet.

Two important innovations played key roles:

hypertext

graphical user interfaces (GUIs)


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Origins of Hypertext

1945: Vannevar Bush speculated engineers wouldeventually build a machine that would store apersons books, records, letters, and research results

on microfilm. Mechanical aids would help retrieve.

1960: Ted Nelson described similar system wheretext on one page links to text on other pages. Hecalled it hypertext.

1960s: Douglas Engelbart created first experimental hypertext system on one of the large computers.


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Hypertext and Graphical UserInterfaces Come to the Internet

Hypertext Markup Language (HTML): a languagethat includes a set of codes (or tags) attached to text.

Hypertext Server: a computer that stores fileswritten in HTML; other computers connect to it andread files.

Hypertext Link (hyperlink): points to anotherlocation in the same or another HTML document.


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Web Browser: software that lets users read HTMLdocuments and move from one HTML document toanother through hypertext link tags in each file.

HTML: a subset of Standard Generalized MarkupLanguage (SGML).

SGML: has been used by organizations for many years to

manage large document-filing systems.

GUI (graphical user interface): a way of presentingprogram output using pictures, icons, and other graphicalelements.


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Mosaic: first GUIprogram to read HTMLand use HTMLdocuments hyperlinks to

navigate from page topage on computersanywhere on the Internet.


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The Web and Commercializationof the Internet

Businesses quickly recognized profit-making potentialoffered by a world-wide network of easy-to-usecomputers.

The Netscape Navigator Web browser was an instantsuccess.

Internet Explorer Web browser entered the marketsoon after Netscapes success became apparent.


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Growth of the World Wide Web


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Connection Options

NAPs (network access points) offer connections tolarge organizations and businesses.

Those businesses provide Internet access to otherbusiness and individuals as ISPs.

Internet service providers (ISPs) provide customers

with software to connect to the ISP, browse the Web,send and receive e-mail messages, and performother Internet-related functions.


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Hierarchy of Internet Service Providers


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Connection Bandwidth

Bandwidth: amount of data that can travel through acommunications circuit in one second.

Bandwidth depends on the type of connection ISPhas to the Internet and the kind of connection youhave to the ISP.

Available bandwidth for any type network connectionbetween two points is limited to narrowest bandwidththat exists in any part of the network.


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Bandwidth measured in bits per second (bps).

When you extend your network beyond a local area,

the speed of the connection depends on type ofconnection used.

POTS (or plain old telephone service) is one way toconnect computers or networks over longer

distances.


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Digital Subscriber Line (DSL): higher grade of serviceoffered by some telephone companies.

Integrated Services Digital Network (ISDN): first

technology developed using a DSL protocol; offersbandwidths up to 256 Kbps.

Asymmetric Digital Subscriber Line (ADSL): offerstransmission speeds ranging from 16 Kbps to 9 Mbps.

T1 or T3 connections: often used by businesses andlarge organizations; much more expensive than POTS orISDN connections.


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Internet 2: operated by group of research universities andthe NSF; has backbone bandwidths greater than 10 Gbps.

Cableconnection: increasingly available in the U.S.; candeliver up to 10 Mbps to an individual user.

Satellite connection: appealing to users in remote areas;can download at a bandwidth of approximately 400 Kbps.

Fixed-pointwirelessconnections: offered by somecompanies

technology similar to wireless LANs

limited and more expensive.


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Connecting Through YourSchool or Employer

Many universities and community colleges offer Internet accessto their students, faculty members, and other employees.

Your employer might offer you a connection to the Internetthrough the computer you use in your job.

Most schools and employers have an acceptable use policy(AUP) that specifies the conditions under which you can usetheir Internet connections.

possibly least expensive option

should carefully consider if limitations placed on use of theInternet are greater than the benefits


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Connecting Through anInternet Service Provider

Reliable connectivity at a reasonable price.

Terms of AUPs usually less restrictive.

Offer modem connections to individuals and higherspeed connections to businesses. May also offerDSL connections to individual and businesscustomers.

Quality of service may deteriorate significantly overtime if ISP adds many new customers withoutexpanding bandwidth.


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Connecting Through aDSL Provider

Connections increasingly available in the U.S. and afew other countries.

Significantly faster connection that dial-up service.

Speeds and subscription rates similar to cablemodems.

Sometimes long delays in installation and repairservices.


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Connecting Through YourCable Television Company

Cable modem converts digital signals into radio-frequencyanalog signals similar to television transmission signals.

Signals travel over the same lines that carry cable televisionsignals.

Cable connection can provide very fast downloads to yourcomputer from the Internet (up to 170 times faster than atelephone line connection).

Greatest disadvantage for most people is that cable connectionis not available in all areas.


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Connecting by Satellite

Satellite Internet connections may be only optionavailable in rural areas.

Speeds and monthly fees similar to those of cableand DSL providers.

Installation fee usually considerably higher because

the dish must be installed and aimed at the satellite.


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Summary

The Internet and the Web began in the military and researchcommunities.

The Internet and the Web have become an important worldwideinfrastructure.

The Internet and the Web support many resources through oneof the most powerful communication tools the world has everknown.

There are a number of options for connecting your computerand the computers of businesses and other organizations to theInternet.

Documents

Internet Tutorial.01