Slide 1 Computer Confluence 7/e © 2006 Prentice-Hall, Inc.

Slide 1

Computer Confluence 7/e

© 2006 Prentice-Hall, Inc.

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Chapter 8

Networking and Telecommunication


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Computer Confluence 7/e Chapter 8Objectives

Describe the basic types of technology that make telecommunication possible

Describe the nature and function of local-area networks and wide-area networks

Discuss the uses and implications of email, instant messaging, teleconferencing, and other forms of online communication


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Computer Confluence 7/e Chapter 8

Objectives (continued)

Explain how wireless network technology is transforming the ways people work and communicate

Describe current and future trends in telecommunications and networking


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Arthur C. Clarke’s Magical Prophecy Clarke’s laws

If an elderly but distinguished scientist says that something is possible, he is almost certainly right, but if he says that it is impossible he is very probably wrong

The only way to find the limits of the possible is to go beyond them into the impossible

Any sufficiently advanced technology is indistinguishable from magic


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Arthur C. Clarke’s Magical Prophecy Arthur C. Clarke’s most famous work was the

monumental 1968 film 2001: A Space Odyssey, in which he collaborated with movie director Stanley Kubrick

Clarke’s most visionary work may be a paper published in 1945 in which he predicted the use of geostationary communications satellites—satellites that match the Earth’s rotation so they can hang in a stationary position relative to the spinning planet below, relaying wireless transmissions between locations on the planet


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Basic Network Anatomy

A computer network is any system of two or more computers that are linked together

How is networking important? People share computer hardware, thus reducing

costs People share data and software programs, thus

increasing efficiency and production People work together in ways that are otherwise

difficult or impossible


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Basic Network AnatomyNetworks Near and Far

A local area network (LAN): computers are physically close to each other, usually in the same building

In a wireless network each node has a tiny radio (or, less commonly, infrared) transmitter connected to its network port Sends and receives data through the air rather than through cables Computers are linked within a

building or cluster of buildings Each computer and peripheral is

an individual node on the network Nodes are connected by cables

which may be either twisted pair (copper wires) or coaxial cable


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Basic Network AnatomyMetropolitan area network (MAN) links two or more LANs within a cityA wide area network (WAN) extends over a long distance

Each network site is a node on the network Data transmitted over common pathways called a backbone


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Basic Network Anatomy Communication frequently happens between LANs and WANs

Bridges and gateways: hardware devices that can pass messages between networks Often translate messages so they can be understood by networks that obey

different software protocols Routers: hardware devices or software programs that route messages as they travel

between networks


Pretty soon you’ll have no more idea of what computer you’re using than

you have an idea of where your electricity comes from.

—Danny Hillis, computer designer

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Basic Network AnatomySpecialized Networks: From GPS to Financial Systems

Global Positioning System (GPS)

Specialized network developed by

U.S. Department of Defense Includes 24 satellites that circle the Earth Each satellite contains a computer, an atomic

clock, and a radio On the ground, a GPS receiver can use

signals broadcast by three or four visible

satellites to determine its position


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Networks that keep our global financial systems running: An Automated Teller Machine (ATM): a specialized terminal linked to a bank’s

main computer through a commercial banking network


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Basic Network AnatomyThe Network Interface

A network interface card (NIC) permits

direct network connection: Adds an additional serial port to the computer Controls the flow of data between the computer’s RAM

and the network cable

The most common types of networks today require some kind of Ethernet card or port in each computer Ethernet is a popular networking architecture developed in 1976 at Xerox Most newer PCs include an Ethernet port on the main circuit board, so they don’t

require NICs to connect to Ethernet networks


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Communication á la Modem

Modem: a hardware device that connects acomputer’s serial port to a telephone line (for remote access)

May be internal on the system board or external, sitting in a box linked to a serial port

Modem transmission speed is measured in bits per second (bps) and modems generally transmit at 28,000 bps to 56.6K bps

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Computers send digital signals The modem (modulator/demodulator) converts the digital signals to

analog so that the message can be transmitted through telephone lines

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Broadband connection—a connection with much greater bandwidth than modems have

DSL uses standard phone lines and is provided by phone companies in many areas

Cable modems provide fast network connections through cable television networks in many areas

High-speed wireless connections can connect computers to networks using radio waves rather than wires

Satellite dishes can deliver fast computer network connections as well as television programs

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Fiber Optic ConnectionsDSL and cable modems have nowhere near the bandwidth of the fiber optic

cables that are replacing copper wires in the worldwide telephone network A fiber optic network can rapidly and reliably transmit masses of multimedia data at

the same time that it’s handling voice messages

NETWORKS ARE BUILT ON PHYSICAL MEDIA

Type Uses Maximum Operating Principal Distance (without amplification)

Cost

Twisted pair Small LANs 300 feet Low

Coaxial cable Large LANs 600–2,500 feet Medium

Fiber optic Network backbones; WANs 1–25 miles High

Wireless/infrared LANs 3–1,000 feet (line of sight) Medium

Wireless/radio Connecting things that move Varies considerably High

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Wireless Network Technology

A lightning-fast network connection to your desktop is of little use if you’re away from your desk most of the time; when bandwidth is less important than mobility and portability, wireless technology can provide practical solutions The fastest growing wireless LAN

technology is known as Wi-Fi or 802.11b

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Another type of wireless technology is Bluetooth Named for a Danish king who overcame his country’s religious differences Overcomes differences between mobile phones, handheld computers, and PCs, making

it possible for all of these devices to communicate with each other regardless of operating system

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Chapter 8 Basic Network Anatomy


With Bluetooth it’s possible to create a personal area network (PAN)—a network that links a variety of personal electronic devices so they can communicate with each other

Bluetooth technology is currently limited to simple device connectivity, but in the future it will open up all kinds of possibilities: A pacemaker senses a heart attack and notifies the victim’s

mobile phone to dial 911 A car radio communicates with parking-lot video cameras

to find out where spaces are available

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A pen scans business cards and sends the information to a PDA inside a briefcase

A medical wristband transmits an accident victim’s vital information to a doctor’s handheld computer

A cell phone tells you about specials on clothes that are available in your size as you walk past stores in a mall

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Communication Software

Protocol is a set of rules for the exchange of data between a terminal and a computer or between two computers

Communication software establishes a protocol that is followed by the computer’s hardware

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Many forms: Network operating system (NOS)

Handles communications between many workstations Client/server model

One or more computers act as dedicated servers and all the remaining computers act as clients

Peer-to-peer model Every computer on the network is both client and server

Many networks are hybrids, using features of theclient/server and peer-to-peer models

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The Network AdvantageWhy do people use networks?

To share computer resources (hardware and software) To support working together in new and different ways

Microsoft Exchange, the most widely-used groupware product, combines email, scheduling, contacts, tasks, and other personal information management features to facilitate information sharing and workgroup collaboration

Exchange Server is the server end of a client/server solution that also includes Microsoft Outlook or its Web-based equivalent, Outlook Web Access (OWA), which is shown here

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Basic Network AnatomyA Home Computer Network


Firewall/router

USB Cable

DSL Modem

Wireless laptop

Multiplayer Games

Wireless access point

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Chapter 8 Email, Instant Messaging, and Teleconferencing:

Interpersonal Computing


The Many Faces of Email

Email system enables you to send and receive messages to others on the

network Web-based email systems and many older UNIX-based programs require that

read and unread messages be stored in post office boxes or folders on the remote mail servers

Many email messages are plain ASCII text

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Even if their software can display HTML mail, not all email users want HTML emailsHTML encoding can slow down an email programAn HTML email message can also carry a Web bug

Most email programs can send and receive formatted word processor documents, pictures, and other multimedia files as attachments to messages

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Mailing Lists Mailing lists enable you to participate in email discussion groups on special-

interest topicsSubscribing to a busy list might mean receiving hundreds of messages each

day To avoid being overwhelmed by incoming mail, many list members sign up to

receive them in daily digest form Some lists are moderated to ensure that the quality of the discussion remains high

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Network NewsNewsgroup: a public discussion on a particular subject

Notes written to a central Internet site Redistributed through a worldwide newsgroup network called USENET Listserv mail messages are delivered automatically to your mailbox, but you have

to seek out information in newsgroups Mailing list messages are sent to a specific group of people, whereas newsgroup

messages are available for anyone to seeModerated newsgroups contain only messages that have been filtered by

designated moderators

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Rules of Thumb: Online Survival Tips

If you don’t have to be on line, go off lineAvoid peak hoursLet your system do as much of the work as possibleStore names and addresses in an on-line address bookProtect your privacyCross-check on-line information sourcesBe aware and awakeAvoid information overload

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Instant Messaging and Teleconferencing:Real-Time Communication

Mailing lists and newsgroups are delayed or asynchronous communication The sender and the recipients don’t have to be logged in at the same time

Instant messaging (IM) has been possible since the days of text-only Internet access

Newer, easier to use messaging systems from AOL, Microsoft, Yahoo, Apple, and others have turned instant messaging into one of the most popular Internet activities

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Online services also offer chat rooms—public or private virtual conference rooms where people with similar interests or motivations can type messages to each other and receive near instant responses

Several IM programs make it possible to carry on two-way video teleconferences

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Computer Telephony Voice mail: a messaging system with the ability to store, organize, and forward

messages An example of a growing trend toward computer telephony integration (CTI)—the

linking of computers and telephones to gain productivity

It’s also possible to send voice signals through a LAN, a WAN, or the Internet, bypassing the phone companies (and their charges) altogether

Handheld PDA computers use software to integrate the functions of a PDA, a phone, and an Internet terminal

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Online communication enables decisions to evolve over timeOnline communication makes long-distance meetings possibleEmail and instant messaging emphasize the message over the messenger

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Online Issues: Reliability, Security, Privacy, and Humanity

Email and teleconferencing are vulnerable to machine failures, network glitches, human errors, and security breaches

Email can be overwhelmingEmail can be unsolicitedEmail can pose a threat to privacy

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Email can be faked Email works only if everybody plays Email and instant messaging filter

out many “human” components of communication

Problems notwithstanding, email and electronic messaging have become fixtures in businesses, schools, and government offices everywhere

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Digital Communication in PerspectiveMany services we take for granted today—video rentals, cable TV,

newspapers, and magazines, for example—will be transformed or replaced by digital high-bandwidth interactive delivery systems of the future

At the same time, entirely new forms of communication are likely to emerge

Telecommunications technology is rapidly changing our lives, and the changes will accelerate as the technology improves

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Rules of Thumb: Netiquette Say what you mean, say it with care and keep it short Proofread your messages Don’t assume you’re anonymous Learn the “nonverbal” language of the Net Keep your cool Don’t be a source of spam Send no-frills mail Check your FAQs Give something back

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Chapter 8 Inventing the Future: A World Without Wires

© 2006Prentice-Hall, Inc.

Most of us connect to the Internet through wiresWi-Fi, or 802.11b, a wireless multiband LAN technology

Built on Ethernet’s data packets and Internet protocols Turning up in home networks, public buildings, and neighborhood freenets

Several other promising technologies are being tested and refined in research labs Ultrawideband Mesh networks Adaptive radio Software-defined radio

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Chapter 8 Inventing the Future: A World Without Wires

© 2006Prentice-Hall, Inc.

We stand at the brink of a transformation. It is a moment that echoes the birth of the Internet in the mid-’70s…This time it is not wires but

the air between them that is being transformed. — Chris Anderson, Editor in Chief, Wired

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Lesson Summary

Networking is one of the most important trends in computing todayLANs are made up of computers that are close enough to be directly

connected with cables or wireless radio transmitters/receiversMost LANs include shared printers and file servers

WANs are made up of computers separated by considerable distanceMany computer networks are connected together through the Internet so

messages and data can pass back and forth among themSome specialized networks, including global positioning systems and

financial systems serve unique functions


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Lesson Summary (continued)

Most computer networks today use the Ethernet architecture; an Ethernet port is a standard feature on most modern PCs

Communication software takes care of the details of communication between machines—details like protocols that determine how signals will be sent and received

Email, instant messaging, and teleconferencing are the most common forms of communication between people on computer networks

It’s not clear how all of these emerging technologies will converge; what is clear is that the wireless revolution is far from over


Slide 1 Computer Confluence 7/e © 2006 Prentice-Hall, Inc.

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