Networking and

Telecommunications

9

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Chapter Outline

• Linking Up: Network Basics

• Electronic Mail, Teleconferences, and Instant Messages: Interpersonal Computing

• Converging Communication Technologies: From Messages to Money

“Any sufficiently advanced technology is indistinguishable from magic.”

Arthur C. Clarke

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Linking Up: Network Basics

• Cost– allows people to share hardware

• Efficiency & Productivity– allows people to share data and software

• Opportunity– allows people to work together in ways

that are otherwise difficult or impossible

Why is networking important?

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Basic Network Anatomy

• A computer network is anycomputer system that linkstwo or more computers

• There are three essentialcomponents in a network:

– Hardware

– Software

– People

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The Network Interface

• A Network Interface Card (NIC):– Is needed to connect directly to a

network

– Adds an additional port to the computer

– Controls the flow of data between the computer’s RAM and the network cable

– Converts the computer’s digital signals into the type required for the particular network

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• A modem is needed to connect a computer to a phone line

Communication á la Modem

• The computer communicates with digital signals

• The telephone system was designed to transmit voice signals, which are analog

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aa

Terminal

Modem

Modem

Analogsignals

Phone line

Digitalsignals

Digitalsignals

Computer

The word modem comes from theterms modulation and demodulation

How a Modem Works

ModulationDemodulation

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A modem:

– Converts the digital stream of information from a computer to an analog stream in order to send a message on the telephone network

Communication á la Modem

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A modem:

– Converts the analog stream of information received over the telephone network into the digital form that the computer understands

Communication á la Modem

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WAN(Wide Area Network)

LAN(Local Area Network)

Networks Near and Far

There are two general types of computer networks:

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LAN (Local Area Network)

A LAN is a network in which the computers are physically close to each other

– They typically share peripherals (printers and servers)

– Each computer and shared peripheral isa node on the LAN

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A WAN is a network in which the computers are a great distance from one another

WAN (Wide Area Network)

– Connections are made via telephone lines, satellites, and/or microwave relay towers

– Each network site is a node

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WAN (Wide Area Network)

WANs are often made up of LANs

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Communication software includes:

Communication Software

– Software that allows the hardware to interact with various networks

– A network operating system (NOS) which controls information shared between the dedicated server andclient machines

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Client/Server Model

Client software sends requests from the user to the server

Server software responds to client requests by providing data

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• The peer-to-peer model allows every computer on the network to be both client and server

Peer-to-Peer Model

• Peer-to-peer networking is built into some operating systems

• Many networks use a hybrid of client/server and peer-to-peer

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The Network Advantage

Networks allow people to:

– Share computer resources (hardware and software)

– Share data

– Work togetherin new ways

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E-Mail, Teleconferences, & IM: Interpersonal Computing

• Electronic mail, teleconferencing, and Instant messaging (IM) allow communication between two or more computer users

• People can communicate in real time or delayed time

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Real-Time vs.Delayed Communication

Real-time communication (synchronous):

– participants meet in real time

– participants see each other’s typedmessages as they are typed

– examples: Talk and Chat

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Real-Time vs.Delayed Communication

Delayed communication (asynchronous):

– Participants type, post,and read messages attheir convenience

– Participants share an electronic mailboxrelated to the group’spurpose

– Examples: email and Newsgroups

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The Postal Alternative

• Speed

• Accessibility

• Facilitates group communication

• Allows messages to be edited and combined with other documents

• Less intrusive than the telephone

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Advantages of E-mail and Video/Teleconferencing

• Allows decisions to evolve over time

• Emphasizes the message, not the messenger

• Makes long-distance meetings possible through video and tele-conferencing

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Disadvantages of E-mailand Teleconferencing

• Vulnerable to machine errors, human errors, and security breaches

• Can pose a threat to privacy

• Can be faked

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Disadvantages of E-mailand Teleconferencing

• Works only if the recipient responds

• Can be overwhelming

• Both filter out many human components of communication

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Rules of Thumb: On-line Survival Tips

• Work offline unless you must be connected

• Avoid peak hours

• Let the system simplify and streamline your work

• Store names and addresses in an on-line address book

• Protect your privacy

• Cross-check on-lineinformation sources

• Be aware of the amount of time youspend on-line

• Avoid informationoverload

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Converging Communication Technologies:

From Messages to Money

Alternative Technologies:

On-line Information Services • AOL, CompuServe, MSN,

Prodigy

• Members pay a fee for these services

Fax Machines and Modems

“Never in history has distance meant less.”

Alvin Toffler

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Alternative Technologies

Voice Mail and Computer Telephony

Global Positioning System

Video Teleconferencing

E-Money

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Building Bandwidth

The quality of information transmitted through a communication medium depends upon bandwidth.

– Increased bandwidth means faster transmission speed

– Bandwidth is affected by the amount of network traffic, software protocols, and type of network connection

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Fiber Optic Cables

• Fiber optic cables are replacing aging copper lines

• They use light waves to carry information

• They provide data rates over one billion bits per second

• They offer extremely low error rates

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Digital Communication Comes Home

Digital communication lines will soon be available in homes. They will provide us:

• Multi-person video phone conversations

• Universal e-mail

• Customized digital newspapers

• Automatic utility metering

• A variety of entertainment options