Introduction to Information Technology Turban, Rainer and Potter Chapter 6

Introduction to Information TechnologyTurban, Rainer and Potter

Chapter 6 Telecommunications and Networks

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CHAPTER 6TELECOMMUNICATIONS

AND NETWORKS



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Learning Objectives Describe the components of a telecommunications system Describe the five basic types of communication media,

including their advantages and disadvantages Classify the major types of networks Differentiate among the three types of distributed

processing Identify seven telecommunications applications and

describe how they help the organization attain competitive advantage



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Chapter OverviewTelecommunications Systems• Signal•Communications processors•Communications media and channels•Communications carriers and services

Networks

• Local area networks•Wide area networks

Network Communication Software• Network operating system•Network management software•Protocols•Types of data transmission

Network Processing Strategies

• Organizational distributed processing•Open systems and enterprise networking

Telecommunications Applications

• Electronic mail•Video conferencing•Electronic data interchange•Electronic funds transfer•Facsimile•Telecommuting•Distance learning



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Case : Network Managementat Southwest Airlines

The Business Problem

The Solution Network Health

to predict the possible ramifications of shifting network traffic to virtually add and subtract applications and make theoretical changes in transmission capacity through-out the

network to help the network managers monitor network usage

it had to make the transition from its legacy applications to client/severtechnology to maintain service levels and keep up with network traffic volume

The Results Save almost $100,000 in staffing costs in the first year Able to smooth network traffic among reservations centers Shorten customers’ waiting time



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What have we learned from this case??

Case (continued…)

Exchange of data - facilitated by telecommunications technologies - brings a number of very significant changes

Take management of resources very seriously Bring disastrous losses in revenues and customer satisfaction

by minor disruption in telecommunications traffic Understand technology in order to gain and maintain

competitive advantage

Rarely in modern companies do computers work in isolation



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The Telecommunications System Hardware - all types of computers and communication

processors Communications media - the physical media through which

electronic signals are transmitted ,including wireless media Communications networks- the links among computers

and communications devices Communications software- software that controls the

telecommunications system and the entire transmission process Data communications providers- regulated utilities or

private firms that provide data communications services Communications protocols- the rules for transmitting

information across networks Communications applications- electronic data

interchange, teleconferencing, videoconferencing, electronic mail, facsimile, and electronic funds transfer, as well as others



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The Telecommunications System (continued …)

ComputerCommunications

ProcessorCommunications

ProcessorComputer

NetworkSoftware

Communications Channels and Media

Transmitter

Receiver



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Communication Processors

Modem an analog network to carry voice signals or sounds in

an analog wave format Multiplexer

an electronic device that allows a single communications channel to carry data transmissions simultaneously from many sources

Front-end-Processor a small secondary computer dedicated solely to

communication in computer system



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Communication Media and Channels

Cable Media Twisted-pair wire Coaxial cable

base band transmission broad band transmission

Fiber optics optical networking

Copper versus fiber the price differential between copper (cheap) and fiber

(expensive) is beginning to narrow



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Communication Media and Channels (continued …)

Wireless Media Microwave - transmission stations : usually not spaced

more than 30 miles apart Satellite - digital transmission

Geostationary earth orbit (GEO) - 22,300 miles Medium earth orbit (MEO) - 6,000 miles Low earth obit (LEO) - 400 to 1,000 miles Global positioning system - 10,900 miles

Radio use when you do not have to depend on microwave or satellite

links, especially for short ranges



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Wireless Media (continued ...) Infrared

red light not commonly visible to human eyes commonly used in television or videocassette remote

control units Cellular radio technology

transfers calls from one cell to another Mobile computing

occurs on Radio-based networks that transmit data to and from mobile computers

Personal communication services uses lower-power and higher-frequency means



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Characteristics of Communications Media Transmission speed

Bandwidth - range of frequencies available

Baud rate Measured in bits per second (bps)

Transmission mode Asynchronous or Synchronous



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Telecommunications Carriers Common Carriers

the long-distance telephone companies Value-added Carriers

have developed private telecommunications systems and provide services for a fee

Switched Lines a person can access from his or her computer to transmit

data to another computer Dedicated

provide a constant connection between two devices and require no switching or dialing



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Telecommunications Services

Wide-area Telecommunications Services (WATS) method for billing customers who use voice band media extensively

Telephone and Dialing Services Automatic Number Identification (ANI)

Integrated Services Digital Network (ISDN) transfer voice, video, image, and data simultaneously

Digital Subscriber Line (DSL) provide high-speed, digital data transmission



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Networks

Local Area Network (LAN) - connect two or more communicating devices within 2,000 feet LAN Technology

the network gateway connects the LAN to public networks or other corporate networks so that the LAN can exchange information with networks external to it

Private Branch Exchanges (a type of LAN) controls telephone switching at a company site carry both voice and data perform call waiting, call forwarding, and voice mail



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Network TypologiesStar network

Ringnetwork

Bus network

Hierarchicalnetwork Mainframe

Mini-computers

Desktop computers



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Networks (continued …)

Wide Area Network (WAN) - long-haul, broadband (analog) networks covering wide geographic area Value-added Networks (VANs)

private, data-only networks add message storage, tracking, and relay services as well as

teleconferencing services Virtual Private Networks (VPNs)

allow an organization to leverage the robust, shared communication infrastructure of the internet

provide a gateway between a corporate LAN and the Internet allow access to a corporate network’s e-mail, shared files, or intranet, via

an Internet connection



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Network Communications Software

Network Operating Systems Network Management Software Protocols

set of rules and procedures governing transmission of data across a network

line access and collision avoidance identify each device in the communication path example : Ethernet10 BaseT and Transmission Control

Protocol/Internet Protocol (TCP/IP) Open System Interconnection (OSI)



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Seven Layers of the OSI Model1) Physical Layer

Transmits raw bits over a communication channel. Its purpose is to provide a physical connection for the transmission of data among network entities and the means by which to activate and deactivate a physical connection.

2) Data Link Layer

Provides a reliable means of transmitting data across a physical link;break up the input data into data frames sequentially and processes the acknowledgement frames sent back by data into data frames sequentially and processes the acknowledgement frames sent back by the receiver

3) Network Layer

Routes information from one network computer to another; accepts messages from source host and sees to it that they are directed toward the destination. Computers may be physically located within the same network or within another network that is interconnected in some fashion.



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Seven Layers of the OSI Model (continued …)

5) Session Layer

Provides user’s interface into network; where user must negotiate to establish connection with process on another machine. Once the connection is established, the session layer can manage the dialogue in an orderly manner.

6) Presentation Layer

Translates message to and from the format used in the network to a format used at the application layer

7) Application Layer

Includes activities related to users, such as supporting file transfer, handling messages, and providing security.

4) Transport Layer

Provides a network-independent transport service to the session layer, accepts data from session layer, splits it up into smaller units as required, passes these to the network layer, and ensures all pieces arrive correctly at other end.



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Types of Data Transmission Packet Switching

breaks up blocks of text into small, fixed bundles of data called packets

Fiber Distributed Data Interface (FDDI) passes data around a ring, but with a bandwidth of

100 Mbps

Asynchronous Transfer Mode (ATM) divides data into uniform cells eliminates the need for protocol conversion

Switch Hub Technologies turns many small LANs into one big LAN



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Network Processing Strategies Types of Organizational Distributed Processing

Terminal-to-Host Processing File Server Processing Client/Server Architecture and Processing

links two or more computers in an arrangement organizations can make their systems faster and save

money five models of client/server implementation that partition

the three components between the server and the client



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Client/Server ConfigurationTYPES OF CLIENT/SERVER COMPUTING

SEVERS:Distributed

PresentationRemote

PresentationDistributed

Function

RemoteData

Management

DistributedData

ManagementData

ManagementData

ManagementData

ManagementData

ManagementData

Management

Function Function Function

Presentation

PresentationPresentation Presentation Presentation Presentation

FunctionFunction Function

DataManagementNetwork Network Network Network

CLIENTS:Difficult Difficult

MoreDifficult

MoreDifficult

ExtremelyDifficult



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Benefits and Limitations of Client/Server Architecture for Network Processing

BenefitsBenefits The network is not overloaded

with entire files being transferred back and forth

File integrity is much easier to maintain because only the server actually updates the files. File security easier to maintain with server in full control of file data

LimitationsLimitations Microcomputers with

independent processing power are more difficult to coordinate and administer on a network.

There is difficulty in writing software that divides processing among clients and servers.

Specific servers can be slowed when too many clients need service.



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Types of Organizational Distributed Processing

Client/Server Architecture and Processing Peer-to-peer processing

allows two or more computers to pool their resources benefits

» there is no need for a network administrator

» the network is fast and inexpensive to set up and maintain

» each computer can provide backup copies of its files to other computers for security

» it is the easiest network to build



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Open Systems and Enterprise Networking

Open Systems - allows any computing device to be seamlessly connected to and interact with any other computing device, regardless of size, operating system, or application

Connectivity - ability of the various computer resources to communicate with each other through network devices

Enterprise-wide Network

Manu-facturing

Finance

Marketing

Account-ing

AdministrativeServices

and HRM

Corporate BackboneWAN

(Fiber optic cables;FDDI protocol)

Mainframe

EmbeddedLAN

EmbeddedLAN

EmbeddedLAN

EmbeddedLAN

Backbone wide area network

File server for backbone

WAN



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Telecommunications Applications Electronic Mail (e-mail) - computer-based messages

transmitted through telephone wires or wireless networks Videoconferencing - allows people to have “face-to-

face” communications with a group in another location Electronic Data Interchange (EDI) - electronic

transmission of routine, repetitive business documents directly between the computer systems

Electronic Funds Transfer (EFT) - electronically routing funds, debits and credits, and charges and payments



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Telecommunications Applications (continued …)

Facsimiles (FAX) - convert modulated signals into white and black areas for printing

Telecommuting - work at home, using personal computers and telecommunications technology to communicate via electronic mail with other workers, and to send and receive business work

Distance Learning - the students are able to see and hear the professor, and the professor can hear the students off-site; students may be able to see each other



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For Accounting Corporate accountants perform cost/benefit

analyses on the telecommunications infrastructure of the firm

For Finance Financial managers use corporate networks to

transfer and receive funds, complete transactions, and use EFT

What’s in IT for Me?



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What’s in IT for Me? (continued …)

For Marketing Modern telecommunications technologies open

huge conduits of information to and from an organization, and provide great strategic advantage to the marketing function

For Production/Operations Management Telecommunications can make the linkage

between the customer and the production function much more direct, making possible different manufacturing strategies



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What’s in IT for Me? (continued …)

For Human Resource Management Human resource managers utilize their

corporate networks extensively for posting job openings, and use internal corporate networks to publish corporate policies, company newsletters and job openings

Documents

Introduction to Information Technology Turban, Rainer and Potter Chapter 6