2001 Prentice Hall, Inc. All rights reserved. Chapter 5, Internet Hardware, Software and Communications Outline 5.1Introduction 5.2Structure of the Internet

2001 Prentice Hall, Inc. All rights reserved.

Chapter 5, Internet Hardware, Software and Communications

Outline5.1 Introduction5.2 Structure of the Internet5.3 Hardware

5.3.1 Servers5.3.2 Communications Media5.3.3 Storage Area Networks (SANs)

5.4 Connecting to the Internet5.4.1 Digital Subscriber Lines (DSL)5.4.2 Broadband5.4.3 Integrated Services Digital Network (ISDN)5.4.4 T-1 and T-3 Lines

5.5 Internet25.6 Software

5.6.1 Application Service Providers (ASPs)5.6.2 Databases


Chapter 5, Internet Hardware, Software and Communications

Outline5.7 Operating Systems

5.7.1 UNIX5.7.2 Microsoft Windows5.7.3 Linux5.7.4 Mac OS X

5.8 Enhancing Business Communication5.8.1 Intranets and Extranets5.8.2 Streaming Audio and Video5.8.3 Internet Telephony5.8.4 Web Casting and Webconferencing


5.1 Introduction

• Connection media• Cost of connecting• Streaming media (audio and video)• Internet telephony • Technologies used to enhance online business

communications


5.2 Structure of the Internet

• IP address (Internet Protocol)– Computers use IP addresses to locate other computers on the

Internet

• Packet– Source address, a destination address, sequencing

information, error-control information and the data to be delivered to the destination address

• Router– Used to move packets across the Internet efficiently


5.3 Hardware

• The Internet employs many advanced hardware technologies – Various communications media used to connect hosts

– The roles hosts play on the Internet

• Servers• Communications Media• Storage Area Networks (SAN)


5.3.1 Servers

• Server– A host on the Internet that manages network resources and

fulfills requests from clients

– Web servers, e-mail servers, database servers and file servers

– A single server may provide multiple services

• A Web server stores Web pages and delivers the pages to clients upon request

• Protocols for delivering information over the Web– Hypertext transfer protocol (HTTP)

– File transfer protocol (FTP)

– Post office protocol (POP)

– Simple mail transfer protocol (SMTP)


5.3.2 Communications Media

• Communications medium – The hardware that connects computers and other digital

equipment

• Bandwidth– Indicates how much data can be transferred through the

medium in a fixed amount of time

– Usually measured in bits per second (bps)

• Copper wire– The primary communications medium



• Fiber-optic cable– Composed of flexible glass fiber, is thinner and lighter than

traditional copper wire, yet has much wider bandwidth – Uses short bursts of light to represent bits

• Optical modem– Modem stands for modulator and demodulator– Translates digital signals from computers into light through a

process called modulation

• Opto chip– Converts the most basic particle of light, the photon, into an

electric current – Allows tremendous amounts of data to be sent over fiber-

optic networks through particles 100 times smaller than the diameter of a human hair



• The strength of a signal transmitted over a communications medium is reduced as the signal travels farther and farther

• Repeater– Can be used to alleviate this problem by amplifying and

retransmitting the signal across segments of copper wire or fiber-optic cable

• Transmission costs– Fiber-optic cable is more expensive than copper wire

– Installation of fiber-optic cable is more complicated than installation of copper wire

– Fiber-optic cable requires fewer repeaters


5.3.3 Storage Area Networks

• Companies produce large volumes of data to support sales analysis tools, enterprise resource planning (ERP) systems, multimedia Web sites and e-commerce systems

• Storage Area Network (SAN)– Provides high-capacity, reliable data storage and delivery on

a network

– Allows network administrators to collect data in logical groups on data servers distributed throughout the network

– SAN devices store large volumes of data and may also provide backup and recovery services


5.3.3 Storage Area Networks

• Mirroring technology – A SAN device stores redundant copies of data, so that if one

copy is lost or damaged, a mirrored copy can be used

• Fiber-channel technology – A high-speed communications medium based on fiber-optic

technology that provides transfer rates of 100 Mbps

• Network storage devices providers – EMC

– Compaq

– StorageNetworks


5.4 Connecting to the Internet

• Most home users subscribe to an Internet Service Provider (ISP) to connect to the Internet – Some charge fixed monthly fees for Internet access– Some offer free Internet access in return for personal

demographic data

• Analog modem– User connects to an ISP using the modem, which then

connects the user to the Internet– Takes digital signals from the computer and turns them into

analog signals• Analog signals can be transmitted over a telephone line just

like a human voice

– A modem at the ISP then converts the sound back into a digital signal that can be transmitted over the Internet


5.4 Connecting to the Internet

• Free Internet access providers– NetZero– IsFree.com– ACI– Address.com

• Web TV– A low-cost technology for connecting to the Internet through

the user’s television, instead of a PC

– WebTV users can dial into an ISP through a modem to surf the Web, send and receive e-mail and chat with other people

– The basic WebTV system includes a wireless keyboard, an 8.6-GB, a hard drive and a 56-Kbps modem


5.4.1 Digital Subscriber Lines

• Digital Subscriber Lines (DSL)– Offers high-bandwidth Internet access over existing copper

telephone lines

– Splits your phone line into three information-carrying channels

– DSL connections require special hardware at the local telephone company’s central office and at the user’s location



• IAD (integrated access device)– Provides network connections for high-speed Internet

access, as well as connections for multiple voice telephone lines

• ADSL (asymmetric DSL) – the connection speed for sending data to the Internet

(upstream) is slower than the connection speed for receiving data from the Internet (downstream)

• VoDSL (voice over DSL)– Provides voice telephone services and high-speed data

access over a single standard telephone line

• SDSL (symmetric DSL)– Transfers data at the same speed both upstream and

downstream



Method Speed (Kbps) Send Speed = Receive Speed

Cost Availability for Businesses

Modem 33–56 No Very low Universal

Cable modem 64–1500 No Medium Very limited

ISDN 56–128 Yes High Widely available

xDSL 384–55,000 No Low Limited

Frame relay/T1 64–1544 Yes Very high Widely available Fig. 5.1 Internet connection comparison chart. (Courtesy of GLINK, LLC.)


5.4.2 Broadband

• Broadband– A category of high-bandwidth Internet service provided

mainly by cable television and telephone companies to home users

– Can handle voice, data and video information

– Enables videoconferencing, real-time voice and streaming-media applications

– Always connected, eliminating the need to dial into an ISP

• Cable modem– Translates digital signals for transmission over the same

cables that bring cable television to homes and businesses

– Connections is shared among many users


5.4.3 Integrated Services Digital Network (ISDN)

• ISDN (Integrated Services Digital Network)– Provides high-speed connections to the Internet over both

digital and standard telephone lines

– Limited service

– Costly connection

– Divided into three channels that each perform different tasks• Two bearer channels each support data transfers, while the

data channel is used to transmit routing information

– ISDNZone


5.4.4 T-1 and T-3 Lines

• T-1 line– A dedicated connection that supports data rates of 1.544 Mb

per second

– Made up of 24 channels

• T-3 line– Supports data rates of 43Mbps and is made up of 672

channels that each support 64Kbps

• T-1 and T-3 lines can be used for both voice and data communication

• Everythingt1.com


5.5 Internet2

• Consortium developing next generation of the Internet – Abeline

• A high-speed network currently used by Internet2 consortium members, will soon be able to transfer 2.4 gigabits of data per second

– Teleimmersion• Allows users in different locations to share information in real

time—even 3D images

– Virtual laboratory• Enable researchers worldwide to collaborate on projects

– Digital libraries • Storage of audio and video files, enabling a search for a

movie by a line from its soundtrack.


5.6 Software

• Application Service Providers• Databases


5.6.1 Application Service Provider

• Provide customized business software applications over the Internet

• Maintains and updates the application as necessary• Companies can eliminate the costs associated with

developing and maintaining business applications• Virtual private networks (VPNs)

– Allow customers to connect to their applications securely over the Internet

– VPNs use the point-to-point tunneling protocol (PPTP) to create a secure channel of communication between the customer and the ASP


5.6.2 Databases

• Database– An integrated collection of data

• Database management system (DBMS) – Provides mechanisms for storing and organizing data in a

manner that facilitates satisfying sophisticated queries and data manipulations

• Structured Query Language (SQL– Almost universally used with relational database systems to

make queries (i.e., to request information that satisfies given criteria) and manipulate data


5.6.2 Databases

• Relational database model – A logical representation of the data that allows the

relationships between the data to be considered independently of the physical implementation of the data structures

• Popular enterprise-level relational database systems:– Microsoft Sequel Server

– Oracle

– Sybase

– DB2

– Informix


5.7 Operating Systems

• Operating system (OS) – Software that manages the resources on a computer – Multiuser OS

• Allows more than one user to run programs simultaneously

– Multiprocessor OS • Controls a computer that has many hardware CPUs

– Multitasking OS • Allows multiple applications to run simultaneously

– Multithreading OS • Allows an individual program to specify that several activities

should be performed in parallel

• Major operating systems used in desktop computers are UNIX , Linux , Macintosh and Windows


5.7.1 Unix

• Multics– “All things to all people”

– Bell Laboratories, General Electric and Project MAC

• Unix– Developed by Bell Laboratories after leaving the Multics

project

– First version written in assembly language

– Unique design and coherence

– Met the needs of programmers who were building software and of administrators who control software development efforts


5.7.1 Unix

• University of California at Berkley– From time sharing to systems appropriate for studying

distributed computing environments

• Sun Microsystems– Sun OS

– Include facilities for supporting a graphics, window-based, mouse-oriented interface

– Provided facilities for diskless workstations to use the network for file storing, sharing and paging

• The Open Group– Controls the specification for UNIX and holds the trademark

– www.unix-systems.org


5.7.2 Microsoft Windows

• The most popular operating system in the world• Introduced in 1984 with graphical user interface

(GUI) added to the DOS system • Windows 2.0

– Failed to make a large impact in the market– Took too long to open applications, change screens, etc.

• Windows 3.0 – Achieved widespread success

• Windows 95– Introduced a new graphical user interface and increased

performance

• Windows 98, Windows NT and Windows 2000


5.7.3 Linux

• Linux– A UNIX-like operating system that has been developed by

volunteers worldwide

– Initially developed by Linus Torvalds

– Greatest success on the server-side

• Version 1.0– Released in 1994, gained market share to become one of the

world’s most widely used operating systems

• The Gnome Foundation– Founded to develop a free Linux-based desktop environment

and a free application framework to compete with Microsoft Office for the desktop-computer environment


5.7.3 Linux

• Open source software– Freely available source code, so that anyone can use, customize

and make updates to the software

• Kernel– The core of the operating system

• Most of the applications that run on Linux are freely available over the Internet and on many CD-ROM distributions

• GNU General Public License (GPL) – One of the most widely used open-source licenses

– Requires that the source code for GPL-licensed software, as well as the source code for any modifications or improvements to that software, is made freely available to the public


Microsoft.NET

• Microsoft.NET– Weaves together the operating system, the Internet and each

device to create applications and services to be accessed anytime, anywhere, from any device

– Could potentially support UNIX and Linux

• Building and maintaining .NET components– Windows.NET

– Visual Studio.NET

– Integrated development environment (IDE)

– .NET Enterprise Servers and the .NET framework

• .NET applications will be built with XML


5.7.4 Mac OSX

• Achieved great success in the 1980s, dominating the market for GUI-based personal computers

• One of the first widely available systems to use a window-based (i.e., a GUI) interface, a mouse and icons

• Release of Windows challenged MacIntosh sales• Mac OS X operating system

– Core was built using industry open standards based on Unix

• Aqua– New Mac OS X interface


Internet Appliances

• Internet appliances – Desktop devices designed specifically for connecting to the

Internet

– iPAQ Home Internet Appliance

– Netpliance i-opener

• Devices allow you to browser the Web, send and receive e-mail and access streaming media online

• Limited functionality


5.8 Enhancing Business Communication

• Intranets• Extranets• Streaming audio and video • Internet telephony

– Makes PC-to-PC and PC-to-phone calls possible, dramatically reducing the cost of communication

• Web casting• Virtual conferencing• Wireless technology


5.8.1 Intranets and Extranets

• Intranet– An organization’s internal network that uses the TCP/IP

protocols of the Internet

– Only authorized parties, such as the organization's employees, have access to an organization’s intranet

– Used to store internal information

• Extranet – An intranet that is also accessible by authorized external

parties who are not members or employees of the organization

– Members or employees might have unrestricted access to information on the extranet, whereas customers or vendors might have access to a limited subset of that information


5.8.2 Streaming Audio and Video

• Streaming technologies– Allow users to send and process audio and video data

continuously

– Allows users to start playing the audio or video file while it is still downloading

– Users can play music over the Internet

– Users can watch a small video on a Web site


5.8.2 Streaming Audio and Video

RealPlayer dialog. (Copyright© 1995-2000 Realnetworks, Inc. All Rights Reserved. RealNetworks, Real.com, RealPlayer are trademarks registered trademarks of of RealNetworks, Inc.)


5.8.3 Internet Telephony

• Internet telephony– Enables communication over the Internet, allowing you to

use your PC as a telephone

– Cost efficient

• Net2Phone– Service allows you to make free PC-to-telephone calls

within the United States, and international calls at discounted rates

– Net2Phone and other Internet telephony services are not always compatible with systems running firewalls

– ClickTogether service allows companies to add personalized voice capabilities to a Web site


5.8.4 Webcasting and Web Conferencing

• Webcasting – Broadcasting over the Web

– Businesses can stream seminars, conferences, shows, sales presentations and more though their Web sites

– Live or prerecorded

• Web conferencing– Allows businesses to meet and collaborate online, in real

time from anywhere in the world

• Evoke– Webcasting and Web conferencing

Documents

2001 Prentice Hall, Inc. All rights reserved. Chapter 5, Internet Hardware, Software and Communications Outline 5.1Introduction 5.2Structure of the Internet