Introduction to the Internet and the World Wide Web History, Structure, and Getting Connected Tutorial 1

Introduction to the Internet and the World Wide Web

History, Structure, and Getting Connected

Tutorial 1

Objectives

• Obtain an overview of the information and tools that are available on the Internet

• Learn what computer networks and internets are and how they work

• Find out how the Internet and the World Wide Web began and grew

• Compare different methods for connecting to the Internet

Internet and World Wide Web:Amazing Developments

• The Internet is a large collection of computers all over the world connected to one another.

• One of the most amazing technological developments of the 20th century.

• The World Wide Web is a subset of computers on the Internet that has helped make Internet resources available to people who are not computer experts.


• New Ways to Communicate– E-mail– Electronic discussions– Instant messaging

• Information Resources and Software– Newspapers & magazines– Government documents– Research reports & books– Software download sites


• Doing Business Online– Electronic storefronts– Coordinate worldwide operations– Recruit employees

• Entertainment– Review restaurants, movies, theater, musical

events and books.– Interactive games– Follow sports teams

Antivirus

• Won’t learn till later, but you should have antivirus software (and firewall) on your computer.– Norton– McAfee– Etc.

• May be provided by your ISP

Computer Networks

• Network: a collection of connected computers.

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

• Server: computer that accepts requests and shares some or all of its resources with computers to which it is connected.

Client/Server Local Area Networks

• Client: computer connected to a server.

• Network Operating System: software that runs on a server.

• Client/Server Networks: one server computer sharing its resources with multiple client computers.

• Local Area Network (LAN): network of computers located close to each other.

New Perspectives on the Internet, 5eTutorial 1

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Client/Server LAN

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 process large amounts of work.

Connecting Computers to a Network – Types of Cable

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

• Coaxial Cable: 20 times faster than Category 1, more expensive

• Category 5: carries signals between 10 & 100 times faster than coaxial cable, easy to install.

• Fiber-optic cable: most expensive, transmits pulsing beams of light through very thin strands of glass, fastest transmission rate.

Types of Cable


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TWISTED-PAIR

COAXIAL

FIBER-OPTIC

Wireless Networks

• Becoming more common as costs drop.

• Old buildings -- expensive to install wiring.

• Companies which use laptop computers.

• Schools -- classrooms, libraries, and study lounges.

• Homes.

Wide Area Networks

• WAN: a network of networks or an internet.

• Internet: a worldwide collection of interconnected networks; owners have voluntarily agreed to share resources and network connections.

Connectivity: Circuit 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 carries the signal.

Connectivity: Packet Switching

• Packet-switching: files and messages broken down into packets and labeled electronically with codes for their origin and destination.

• Packets travel from computer to computer along the network until they reach their destination.

• Routers determine the best way for a packet to move towards its destination.

Connectivity: Packet Switching

• Datagram – packet with routing info.

• Packet-switched networks more reliable:– rely on multiple routers instead of

central point of control.

– each router can send individual packets along different paths if parts of the network are not operating.

Origins of the Internet

• DARPA (Defense Advanced Research Projects Agency) researchers connected first computer switches in 1969.

• ARPANET grew over next three years to include over 20 computers. Grandpa of Internet.

Open Architecture Philosophy

– Independent networks should not require any internal changes to be connected to the Internet.

– Packets that do not arrive at their destinations must be retransmitted from their source network.

– The router computers do not retain information about the packets they handle.

– No global control will exist over the network.


• Protocol: Rules for formatting, ordering, and error-checking data sent across a network.

• New set of protocols developed in 1970 by Vincent Cerf 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.

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

• Vincent Cerf considered to be the father of the Internet by many.

Birth of E-Mail:A New Use for Networks

• Ray Tomlinson, an ARPANET researcher, wrote a program that could send and receive messages over the network in 1972.

• E-mail was born and rapidly became widely used in the computer research community.

• ARPANET continued to develop faster and more effective network technologies.

• Began sending packets by satellite in 1976.

More New Uses for Networks Emerge

• File Transfer Protocol (FTP) - transfer files between computers.

• Telnet - users log in to their computer accounts from remote sites.

• Mailing lists (LISTSERV), information posting areas (Usenet), and adventure games among new applications appearing on the ARPANET.

Commercial Interest Increases

• National Science Foundation (NSF) prohibited commercial network traffic on its networks.

• Larger firms built TCP/IP-based WANs that used leased telephone lines to connect field offices to corporate headquarters.

• NSF permitted commercial access. Initially there was resentment but business invested much money, speed increased and costs fell.

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

• Extranet: an intranet that allows selected outside parties to connect.

• ARPANET grew from 4 computers in 1969 to over 300,000 by 1990.

Commercial Interest Increases

Growth of the Internet

• Formal definition of Internet was adopted in 1995 by the Federal Networking Council (FNC).

From Research Project to Information Infrastructure


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Growth in number of Internet hosts

Growth of the Internet

• Number of hosts connected to Internet includes only computers directly connected to the Internet.

• Internet traffic now carries more files that contain graphics, sound, and video, so Internet files have become larger.

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 access to the Internet through their NAPs to organizations and businesses.

• The NSFnet still exists for government and research use.


• More than 180 million connected host computers and more than 700 million worldwide Internet users.

• TCP/IP numbering system that identifies users on the Internet is running short of numbers.

– IP version 4 provides a maximum of about 4 billion addresses.

– IP version 6 approved in 1997 by the IETF allows existing users to continue accessing the Internet while new system is being implemented.


• The Internet has become one of the most amazing technological and social accomplishments of the century.

• Computers linked to this interconnected network are located in almost every country of the world.

• Billions of dollars change hands every year over the Internet.

World Wide Web

• World Wide Web: a way of thinking about information storage and retrieval. Can view multimedia documents (text, graphics, audio, and video.

• Web: software that runs on some of the computers connected to each other through the Internet.

• In 1990, Tim Berners-Lee of CERN developed the World Wide Web.

• HTTP: Protocol that transfers Web pages.

Hypertext

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

• Hypertext Server: a computer that stores files written in HTML; other computers connect to it and read files.

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

Hypertext

• Web Browser: software that lets users read HTML documents and move from one HTML document to another through hypertext link tags in each file.

• HTML is a subset of Standard Generalized Markup Language (SGML) which has been used for many years to manage large document-filing systems.

GUI

• GUI (graphical user interface): a way of presenting program output using pictures, icons, and other graphical elements.

• e.g. CoreFTP vs. command line• Much easier to learn and use• Point and click

Hypertext and Graphical UserInterfaces Come to the Internet

• Mosaic: first GUI program to read HTML and use HTML documents’ hyperlinks to navigate from page to page on computers anywhere on the Internet.

Commercializationof the Internet

• Businesses quickly recognized profit-making potential offered by a world-wide network of easy-to-use computers.

• The Netscape Navigator Web browser was an instant success.

• Internet Explorer Web browser entered the market soon after Netscape’s success became apparent.


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Growth of the World Wide Web

Connection Options

• NAPs (network access points) offer connections to large organizations and businesses.

• Those businesses provide Internet access to other business 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 perform other Internet-related functions.


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Hierarchy of Internet Service Providers

Connection Bandwidth

• Bandwidth: amount of data that can travel through a communications circuit in one second.

• Bandwidth depends on the type of connection ISP has to the Internet and the kind of connection you have to the ISP.

• Available bandwidth for any type network connection between two points is limited to narrowest bandwidth that exists in any part of the network.

Connection Bandwidth

• Bandwidth measured in bits per second (bps).

• When you extend your network beyond a local area, the speed of the connection depends on type of connection used.

• POTS (or plain old telephone service) is one way to connect computers or networks over longer distances. 28-56 kbps

Connection Bandwidth• Digital Subscriber Line (DSL): higher grade of

service offered by some telephone companies.

• Integrated Services Digital Network (ISDN): first technology developed using a DSL protocol; offers bandwidths up to 256 Kbps.

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

• T1 or T3 connections: often used by businesses and large organizations; much more expensive than POTS or ISDN connections.

Connection Bandwidth• Cable connection: increasingly available in the

U.S.; can deliver 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-point wireless connections: offered by some companies– technology similar to wireless LANs– limited and more expensive.

Internet2

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

• Develop new technologies that will be rapidly deployed to expand the Internet.

http://www.internet2.edu/about/

• Internet2 is a consortium being led by 207 universities working in partnership with industry and government to develop and deploy advanced network applications and technologies, accelerating the creation of tomorrow's Internet. Internet2 is recreating the partnership among academia, industry and government that fostered today´s Internet in its infancy.

• The primary goals of Internet2 are to: – Create a leading edge network capability for the national

research community – Enable revolutionary Internet applications – Ensure the rapid transfer of new network services and

applications to the broader Internet community.

Connecting Through YourSchool or Employer

• Many universities and employers offer Internet access to their students, faculty members, and employees.

• Most schools and employers have an acceptable use policy (AUP) that specifies the conditions under which you can use their Internet connections.– possibly least expensive option– should carefully consider if limitations placed on

use of the Internet are greater than the benefits

Connecting Through anInternet Service Provider

• Reliable connectivity at a reasonable price.

• Terms of AUPs usually less restrictive.

• Offer modem connections to individuals and higher speed connections to businesses. May also offer DSL connections to individual and business customers.

• Quality of service may deteriorate significantly over time if ISP adds many new customers without expanding bandwidth.

Connecting Through a DSL Provider

• Connections increasingly available in the U.S. and a few other countries.

• Significantly faster connection that dial-up service.

• Speeds and subscription rates similar to cable modems.

• Sometimes long delays in installation and repair services.

Connecting Through YourCable Television Company

• Cable modem converts digital signals into radio-frequency analog signals similar to television transmission signals.

• Signals travel over the same lines that carry cable television signals.

• Cable connection is up to 170 times faster than a telephone line connection.

• Cable connection is not available in all areas.

Connecting by Satellite

• Satellite Internet connections may be only option available in rural areas.

• Speeds and monthly fees similar to those of cable and DSL providers.

• Installation fee usually considerably higher because the dish must be installed and aimed at the satellite.

Summary• The Internet and the Web began in the military and

research communities.

• The Internet and the Web have become an important worldwide infrastructure.

• The Internet and the Web support many resources through one of the most powerful communication tools the world has ever known.

• There are a number of options for connecting your computer and the computers of businesses and other organizations to the Internet.

Documents

Introduction to the Internet and the World Wide Web History, Structure, and Getting Connected Tutorial 1