The Internet, intranets, extranetsCh-7-

The Internet

• The largest computer network in the world• Is a network of networks owned by governments,

universities, nonprofit groups, and companies.• Exchange information by using the same open,

nonproprietary standards and protocols.• Connected via high-speed, long-distance backbone

networks.• Forms a massive electronic communications

network among businesses, consumers, government agencies, schools, and other organizations worldwide.

The evolution of the Internet

• The Internet began as one network, called the ARPANET in 1969.• ARPANET for military and scientific activities (defense

research).• ARPANET was split into two networks in 1980.• UUCP, worldwide UNIX communications network, and

USENET for academic and commercial organizations.• CSNET and BITNET nationwide networks for academic

and research activities.• NSFNET linked researchers across the country with five

supercomputer centers.

The Internet Today• In 1998, less than 2 percent of the world’s adults had access to

the Internet.• In 2001, 500 million people worldwide were Internet users• In June 2012,

Internet Divide 2013

• Countries with a higher gross domestic product per person will have higher rates of personal computer ownership and higher Internet adoption rates than those with lower GDP figures.

Infrastructure of the Internet

• Commercial communications companies provide largely the physical network backbone of the Internet.

• U.S government and the National Science Foundation (NSF) contribute some funds to essential administrative processes, such as standards development and the domain name system (DNS), through contracts with private organizations that perform these functions.

• The Internet infrastructure is supplied by network service providers such as UUNET, MCI WorldCom company, GTE Internetworking, etc.• Businesses and individual subscribers connect to

the Internet through these and other smaller Internet Service providers.• The provider may be a large backbone provider,

or may be a smaller local company connecting to the larger network service provider.• ISP: Internet service providers are both

backbone and access providers.

• Backbone providers should be connected to one another and to access providers over backbone networks.

How the Internet work?

WorldCom

Frontier

FrontierZip

MCI

Sprint

ISP

Fred

Peer Customer

Peer

Peer

Peer

Peer

Susan

Public Peering Point

How The Internet Works?

• The ISP maintains a pool of modems for their dial-in customers. • This is managed by some form of

computer (usually a dedicated one), which controls data flow from the modem pool to a backbone or dedicated line router. This setup may be referred to as a port server, as it 'serves' access to the network. Billing and usage information is usually collected here as well.

• After the packets traverse the phone network and the ISP's local equipment, they are routed onto the ISP's backbone or a backbone the ISP buys bandwidth from. • From here the packets will usually journey

through several routers and over several backbones, dedicated lines, and other networks until they find their destination, the computer with address 5.6.7.8 (for example).

(IP) Internet Protocol

• The set of rules used to send and receive packets from one machine to another over the Internet.• The IP and TCP protocols are

commonly used together that they are referred to as the TCP/IP protocol.• The Internet is packet-switching

network.

Internet Addresses

• Each computer connected to the Internet has a unique address called IP address (IP stands for Internet Protocol) .• Internet addresses are in the form ###.###.###.###

where ### must be a number from 0 - 255. • If you connect to the Internet through an Internet

Service Provider (ISP), you are usually assigned a temporary IP address for the duration of your dial-in session. • If you connect to the Internet from a local area network

(LAN) your computer might have a permanent IP address or it might obtain a temporary one from a DHCP (Dynamic Host Configuration Protocol) server.

Here are some example IP Addresses:

• 64.54.23.198

• 244.32.121.100

• 209.178.41.76

• 132.62.128.91

Domain Name

• Consist of multiple parts, separated by dots, and are translated from right to left.• For example: “software.ibm.com”:Com is the name of the top-level specification or the zone.Ibm is the name of the company Software is the name of the computer within the company to which the message is being sent.• The rightmost two letters in a domain name, if present,

represent the country of the website.• For example:“us”, ”ru”, ”it”, ”uk”, ”ca”, ”fr”

Domain Name

• "DNS" is "Domain Name service," and it provides a facility to substitute more human-friendly names for IP Addresses• DNS was designed to map IP Addresses to computer

names• DNS names typically have three parts:The computer's name, also called the "hostname."The responsible organization's name or

abbreviation.A suffix that identifies the type of organization or its

country of origin.

Domain Name

• Network names, such as 'unc.edu,' are commonly referred to as 'Domain Names' or just 'Domains.' • Full/specific names, such as 'www.unc.edu,' are

often referred to as 'fully-qualified hostnames' or just 'hostnames.‘• When an organization decides it needs a Domain

Name for its network, a representative of that organization contacts a 'Domain Name Registrar' to register the name.

• This Domain Name Registrar is an organization (usually a commercial company) that has the ability to save new Domain Names to the Top-Level Servers and ensure their uniqueness. • Organizations are not allowed to choose a Domain

Name that is already in use, and they cannot permanently own those names. Domain Names are leased, like automobile leases. In order to keep a Domain Name, an organization must continue to renew the lease before it expires. If a lease expires without being renewed, the Domain Name becomes available for other organizations to lease it.

Accessing the Internet

• Connect via LAN server

• Connect Via Serial Line Internet Protocol/Point-to-Point Protocol (SLIP/PPP)

• Connect via online service.

Connect via LAN server• The user’s computer must have a communications stack• Communications stack: Is specialized software that provides a set of communications protocols that perform the complete functions of the seven layers of the OSI communications model.• Speed of 56kbps or faster• Expensive but cost spread over many users.

Connect via SLIP/PPP• Users should have modem and specialized software that

allows them to dial into a SLIP/PPP server through a service provider .

• Company’s intranet or employees who work at home.

Connect via online service• Requires a modem, standard communications software, and

an online information service account with an Internet service provider.

How can you connect to the Internet?

Slow-speed technology

Slow-speed technology

Dial-up accessmodem in your computer uses a

standard telephone line to connect to the Internet

Dial-up accessmodem in your computer uses a

standard telephone line to connect to the Internet

Connection must be established each time you log on. Slow but inexpensive

Connection must be established each time you log on. Slow but inexpensive

High-speed connection

High-speed connection

Digital subscriber line (DSL), cable telephone Internet

services (CATV), cable modem,fixed wireless, and satellite modems

Digital subscriber line (DSL), cable telephone Internet

services (CATV), cable modem,fixed wireless, and satellite modems

Connection is always on—whenever the computer

is running

Connection is always on—whenever the computer

is running

Most Internet access methods used in homes involve a small hardware unit called a modem that connects to a physical medium supporting one of these fixed location services: • phone line (for DSL) • cable Internet (CATV) line • fiber optic cable • wireless antenna (for satellite and wireless broadband

services)

• Portable computers, like tablets, can be connected to fixed location networks inside a home, but they additionally support mobile broadband Internet access via cellular networks that can be used at home and while traveling.

• outside the home, portable computers can also reach the Internet via Wi-Fi hotspots, hardware access points installed in fixed locations that are in turn networked to Internet service through one of the other above methods.

Who controls the Internet?No onec—cit is a public, cooperative, and

independent networkSeveral organizations set standards

World Wide Web Consortium (W3C)

Oversees research, sets standards and guidelines

Tim Berners-Lee, director

Internet2 (I2)Internet-related research

and development project

Develops and tests advanced Internet

technologies

What is the World Wide Web?

A worldwide collection of electronic documents

Each electronic document is called a Web page

Also called the Web

Can contain text, graphics, sound, video, and built-in connections

A Web site is a collection of related Web pages

World Wide Web• The Internet functions as the transport mechanism• www or W3 is an application that uses those transport

functions.• E-mail is another application run on the Internet.• Web is a system with universally accepted standards for

storing, retrieving, formatting and displaying information via a client/server architecture.

• Web uses GUI.• Web is based on a standard hypertext language called

Hypertext Markup Language (HTML)

• Offering information through the Web requires establishing a home page.

• Home page : is a text and graphical screen display that usually welcomes the user and explains the organization that has established the page.

• Home page lead users to other pages.• Web site: is all the pages of a particular company or individual.• Uniform Resource Locator (URL): is the address of a specific

resource on the Web, e.g. : URL for Microsoft is http://www.microsoft.com

• URL: Unique address for a Web page:A web server delivers the Web page to your computer

• HTTP: Hypertext Transport Protocol which is the communications standard used to transfer pages across the WWW.

• HTTP: defines how messages are formatted and transmitted and what actions Web servers and browsers should take in response to various commands.

• Browser: is a software application used by users to access the Web.

• A Browser is able to communicate via HTTP, managing HTML, and displaying different data types.

What is a Web browser?

• Program that allows you to view Web pages

MicrosoftInternetExplorer

Netscape

MozillaOpera

Safari

Internet Regulation• Technical organizations such as the Internet Engineering Task

Force and the World Wide Web Consortium, define the standards that govern the Internet’s functionality.

• Regulate the content of Internet-connected computers:Privacy, security and the legal liability of service providers.• Some content providers have addressed these issues with:Filters, ratings, and restricted address.

Internet Expansion• Slowdowns in retrieval time, unreliable transmission of

streamed data, and denial of service by overloaded servers.• Causes of slowdowns:Improperly configured networksOverloaded serversRapidly changing Internet usage patternsToo much traffic for available bandwidth• Solutions:Installing high-speed transmission mediaBigger, faster routersMore sophisticated load balancing and management softwareLocal caching of frequently requested Web pages to improve

response time

Internet Privacy• Websites collect information with and without consumers’

knowledge.• Through: registration (Amazon.com)• Clickstream data: Information about where people go within a Web site and the content they see.• Clickstream data are collected by cookies.• Cookie:Is a small data file placed on users’ hard drives when they first visit a site.

Intranet• A private network that uses Internet software and TCP/IP

protocols.• A private Internet , or group of private segments of the public

Internet network, reserved for use by people who have been given the authority to use that network.

• Common applications on intranets:Document sharingCorporate telephone directories Human resources formsTraining programsSearch enginesCustomer databases

Intranet security• Public key security ( encryption and certificate authorities)• Encryption: scrambles outgoing data • Digital certificate: like electronic Identification cards to ensure

that the person trying to access is a valid user.• ValiCert is the leader in the certificate authority market.• Firewall: is a device located between a firm’s internal network

and external networks.• Firewall regulates access into and out of a company’s network.• Firewall examines only the header of a packet• Assured pipeline examines the entire request for data and

then determines whether the request is valid.

Extranet• Interorganizational information system• Enable people who are located outside a company to work

together with the company’s internally located employees.• Networks that link business partners to one another over the

Internet.• Extranet= extended intranet• Closed to the general public• Extranet uses virtual private network (VPN) technology to

make communications over the Internet more secure.

Types of extranets• A company and its dealers, customers, or suppliers• An industry’s extranet: the major players in an industry may team up to create an extranet that will benefit all.• Joint ventures and other business partnerships:Several companies partner on a joint venture and use the extranret as a vehicle for communications and collaboration

Enterprise Information Portals• EIP:Web-based applications that enable companies to access internally and externally stored information, and provide users a single point of access to personalized information needed to make informed business decisions.• EIPs integrate:Content management, business intelligence, data warehouse, data mart and data management applications.

Mobile Internet• Refers to the use of wireless communications technologies to

access network-based information and applications from mobile devices.

• Mobile Internet= wireless Web

How do handheld computers and cellular telephones access

the Web?Use a microbrowser that displays Web pages that

contain mostly textMust be Web-enabled