Copyright © 2011 Pearson Education, Inc. publishing as Pre - PowerPoint Presentation

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Copyright © 2011 Pearson Education, Inc. publishing as Pre - PPT Presentation

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MANAGING INFORMATION TECHNOLOGY7th EDITION

CHAPTER 3

TELECOMMUNICATIONS AND NETWORKINGSlide2

2PART 1: IT BUILDING BLOCKSSlide3

3-3

NETWORKING AND TELECOMMUNICATIONS.

NETWORKING

The electronic linking of geographically dispersed devices

TELECOMMUNICATIONS

Communications at a distance, including voice and data

- Also referred to as: data communications, datacom,

teleprocessing, telecom, and networkingSlide4

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OVERVIEW OF TELECOMMUNICATIONS AND NETWORKINGTelecommunications and networking have become increasingly important to businesses because of distributed processing and globalizationSlide5

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THE TELECOMMUNICATIONS INDUSTRYThree Major Segments of Telecom Industry:Carriers who own or lease physical plant & sell the service of communications transmissionEquipment vendors who manufacture and sell telecommunications equipment

Service providers who operate and deliver network services or provide access to or deliver services via the InternetSlide6

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THE TELECOMMUNICATIONS INDUSTRYExample: AT&TOne of largest carriers in U.S. industry

In 1984, AT&T split into several companies as a result of a US Department of Justice antitrust lawsuit

Breakup of AT&T led to greater innovation through competition

But recent trend has been consolidation in the industrySlide7

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REASONS FOR NETWORKINGFive primary reasons for networkingSharing of technology resources

Sharing of data

Distributed data processing and client/server systems

Enhanced communications

Marketing outreachSlide8

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REASONS FOR NETWORKING1. Sharing of technology resources:Prior to networking capabilities, computers could not even share printers….Today, PCs share software, mainframes share storage devices, etc.

2. Sharing of data:

Enables retrieval of data stored on other nodes in the network

Allows efficient transactions between businesses, their suppliers, and their customers, based on up-to-date data

Some businesses share many terabytes of data per day

Sharing of data via Internet usersSlide9

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REASONS FOR NETWORKINGDistributed data processing and client/server systems: Distributed data processingInformation processing that uses multiple computers at multiple sites that are tied together through telecommunication lines

Client/server systems

A type of distributed system in which the processing power is distributed between a central server and a number of client computers

Client

Server

Transfer of DataSlide10

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REASONS FOR NETWORKING4. Enhanced communications:Telecommunication networks provide the ability to communicate through Email, Bulletin Boards, Blogs, Instant Messaging, Wikis, Social network sites, VideoconferencingLinks between organizations can lead to strategic alliancesSABRE airline reservation system

Electronic data interchange (EDI)

5. Marketing outreach:

Sharing data via the Internet with consumers = an important marketing and sales channelSlide11

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FUNCTIONS OF A TELECOMMUNICATIONS NETWORKA telecommunications network is more than a series of wires or wireless signals…

Table 3.1Slide12

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ANALOG AND DIGITAL SIGNALSAnalog Signals A signal in which some physical property continuously varies across time

Digital Signals

A signal that is not a continuous function of time, but rather a series of discrete values that represent ones and zerosSlide13

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ANALOG AND DIGITAL SIGNALSRepresentation of digital and analog signalsSlide14

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ANALOG AND DIGITAL SIGNALSDigital computer data does not naturally mesh with analog transmission; it must be converted from ones and zeros to analog signalsSolutions:

Modem (Modulator/Demodulator)

Digital networks

Advantages of lower error rates and higher speedsSlide15

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TYPES OF TRANSMISSION LINES Private (dedicated physical lines)Advantage:- Ensures quality of transmission

Disadvantage:

Costly

Switched (such as public telephone network)

Advantage:

- Less costly

Disadvantages:

- Message may take many different routes

- Quality of transmission may degrade Slide16

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TYPES OF TRANSMISSION LINESSimplex Data can only travel in one direction

Half Duplex

Data can travel in both directions, but not simultaneously

Full Duplex

Data can travel in both directions at onceSlide17

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TRANSMISSION MEDIATwisted PairLiterally, wires that are twisted to reduce interferenceCan be shielded (STP) or unshielded (UTP), but the most commonly used is UTPMedium used for public telephone networks Transmission speeds vary greatlySlide18

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TRANSMISSION MEDIACoaxial (Coax) CableBaseband- Inexpensive, designed for digital transmissionBroadband- Originally for analog, now used for digital

- Commonly used in television cable

Figure 3.2Slide19

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TRANSMISSION MEDIA WirelessNot truly a transmission medium, but rather a broadcast technology in which radio signals are sent through the air

Cordless telephones and cellular telephones now widely used

Wireless technologies:

Wireless LANs

Microwave

Line of sight

Satellite

Long distances

Line of sight

RFID

Bluetooth

Wireless CardsSlide20

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TRANSMISSION MEDIAWirelessWireless LANs- Growing in popularity- Useful when wiring is not possible

- Slower than some wired solutions

- Allow mobile devices to connect to networkSlide21

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TRANSMISSION MEDIAWirelessMicrowave- Widespread use for several decades

- Line of sight transmission

- Limited to 25-50 mile distances because of curvature of the earth

- Expensive, but less costly than fiber optic cables

Microwave TowerSlide22

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TRANSMISSION MEDIAWireless

Satellite

Geostationary Earth Orbit (GEO)

- Remains stationary relative to earth

Low Earth Orbit ( LEO)

- 400 to 1000 miles above earth

Figure 3.3Slide23

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TRANSMISSION MEDIALEO projects beginning in 1990sIridium

First major LEO project with 66 satellites

- Faced high operating costs which resulted in bankruptcy

Mostly military subscribers

Globalstar

LEO project with 40 satellites that does not provide global coverage

Teledesic

Ambitious project with original plans to launch 840 satellites

- This was later cut to 288 satellites, then 30, and then the program was cancelledSlide24

24TRANSMISSION MEDIAWirelessRFID- Acronym for Radio Frequency Identification

- An old technology that became popular in business after Wal-Mart required the use of RFID by some of its suppliers to improve inventory and supply chain management

Wal-Mart and RFID

Wal-Mart CIO on RFID

Wal-Mart gets tough with suppliers about RFIDSlide25

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TRANSMISSION MEDIAWirelessRFIDTwo Broad Types of RFID tags:- Active – these tags have their own power supply and can transmit messages continuously, on request, or on a schedule

Cost over $1.00

- Passive – these tags only send a response to an incoming radio signal

Cost in the $0.08 - $0.20 rangeSlide26

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TRANSMISSION MEDIAWirelessBluetoothNamed after Danish King who united DenmarkShort-range radio technology

Designed to consume very little electrical power and be produced at a low cost

Found in a growing number of devices such as cell phones, laptops, headsets, keyboards, mice, and home appliances

Thousands of Bluetooth products in use today

Bluetooth DevicesSlide27

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TRANSMISSION MEDIAFiber OpticsLight pulses through a thin fiber of glass or silicaFaster and more reliable than other media

Large diameter fiber is multimode (multiple light rays at the same time) while smaller diameter is single mode

But smaller diameter fiber has larger capacity due to light rays bouncing less….Slide28

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NETWORK ACCESS FOR INDIVIDUALSInternet Service Providers (ISPs) sell access to the InternetConsumers now have more options including faster broadband connections

- Digital Subscriber Line (DSL) is a connection through a telephone company

- Cable modem is a connection through a cable television company

- Satellite

With one-way service, individuals must obtain uplink service from another provider

Other

Wireless

access may be through a municipal carrier or a private company

Pricing methods for personal Internet access

- Fixed price (usually monthly plans)

But hotels, airports, cafes, etc. now offer Internet access for short periods of time

- Cost based on usage (data transferred)

- Also offered “free” to customers in various locations Slide29

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NETWORK TOPOLOGYNetwork topology = configuration or arrangement of the devices

Figure 3.4

Bus

- All devices are attached to one cable

- Single-point failure

Ring

- Similar to bus, but ends are attached

- Not susceptible to single-point failure

Star

- All nodes are attached to central device

- Susceptible to failure of central device, but easy to identify cable failure

Tree

- Similar to the star, but with a hierarchical structure

Mesh

- Devices link to multiple other devices

- A failure has little impact on the network, but costlySlide30

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NETWORK TYPES Six types: Computer Telecommunications Networks

Local Area Networks (LANs)

Backbone Networks

Wide Area Networks (WANs)

The Internet

Internet2Slide31

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NETWORK TYPESComputer Telecommunications Networks:This was the only type of network until the 1980s

Commonly used in mainframe architectures

Figure 3.5Slide32

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NETWORK TYPESLocal Area Networks (LANs)Standards developed by the Institute for Electrical and Electronic Engineering (IEEE) IEEE 802 is a family of standards for LANs and metropolitan area networks

- Five types of LANs in common use today – 3 wired, 2 wireless

Contention Bus (IEEE 802.3)

Token Bus (IEEE 802.4)

Token Ring (IEEE 802.5)

Wi-Fi (IEEE 802.11)

WiMAX (IEEE 802.16e)Slide33

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NETWORK TYPES - LANContention Bus (IEEE 802.3)- Developed by Xerox- Usually called Ethernet after the original Xerox version- Half-duplex

- All devices must con

tend to use

CSMA/CD protocol for collisionsSlide34

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NETWORK TYPES - LANToken Bus (IEEE 802.4)- A token (special message) is passed among devices- Only the device with the token can transmit a messageImportant for Manufacturing Automation Protocol (MAP)

Token Ring (IEEE 802.5)

- Developed by IBM

Combination of ring topology with use of tokens (used the same way as in token bus

)Slide35

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NETWORK TYPES - LANWi-Fi (IEEE 802.11)- Short for Wireless Fidelity Most common wireless LAN type today

- Uses a shared Ethernet design

- CSMA/CA Protocol

Similar to CSMA/CD, but with less collisions

- Commonly used in offices to supplement wired Ethernet networks and support mobile devices, or in areas where adding hardwiring is problematic

- Many U.S. cities are offering Wi-Fi networksSlide36

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NETWORK TYPESWiMAX (802.16e)- Newest of the network typesSimilar to Wi-Fi, but operates over longer distances and at higher speeds

- Can use both licensed and non-licensed frequencies

Clearwire

= leading vendor at this timeSlide37

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NETWORK TYPESWireless Local Area Networks: Some Implementation Problems - More difficult to secure than other network types- Organizations that offer wireless access to entice customers have problems with non-customers or unprofitable customers overusing the network

- Unauthorized wireless use is also problematic in condos and apartments

Multiple Unsecured Wireless NetworksSlide38

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NETWORK TYPES3. Backbone NetworksConnect LANsKey to internetworking

Figure 3.8Slide39

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BACKBONE NETWORK DEVICESHardware devices for backbone (middle-distance) networks

Hub:

Simple device that forwards all messages to every device attached to it

Wireless Access Point:

Central device that connects wireless LAN to other networks

Bridge:

Connects two LAN segments and only forwards messages that need to go to other segment

Switch:

A multiport bridge; connects two or more LAN segments

Router:

Connects two ore more LANs and only forwards messages that go to the other LANSlide40

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NETWORK TYPES4. Wide Area Networks (WANs)Similar to LANs, but cover greater distances (“long-haul”)

We will consider the following three general types of WANs because they each have advantages and disadvantages:

- Switched Circuit

Dedicated Lines

Packet-switchedSlide41

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NETWORK TYPES - WANSwitched Circuit (or circuit-switched):A single physical path is temporarily created between two nodes for their exclusive communication

Most widely available means of implementing a WAN using a switched circuit connection is to use the ordinary telephone network

Advantages

- Easy to set up

Disadvantages

- Low speed

- High error rates

There are two different pricing schemes available for this service

- Direct Distance Dialing (DDD) - pay for usage

- Wide Area Telephone Service (WATS) - fixed rateSlide42

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NETWORK TYPES - WANDedicated Lines:These are permanent channels exclusive to the business

Advantages

- High capacity

- Low error rates

Disadvantages

Expensive

Two different types of dedicated circuits:

- Leased lines are cable, microwave, or fiber connections

- Satellite circuits are popular for organizations with many global locations

- SONET lines are high-capacity leased fiber lines

Table 3.3

Wide Area NetworksSlide43

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Packet-switched: Multiple connections exist simultaneously over the same physical circuitMessages are broken up into packetsBusinesses use PADs (Packet assembly/disassembly devices) to connect their networks to a common carrier network

Figure 3.9

Advantages

Efficient use of network

- Can be high capacity

Disadvantages

Packets may arrive in different order or with delay

NETWORK TYPES - WANSlide44

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NETWORK TYPES5. The InternetNetwork of networks that use the TCP/IP protocol

Similar to an enormous WAN

733 million hosts as of January 2010

Began with ARPANET and NSFNET

ARPANET (Advanced Research Projects Agency Network) was created by the US Department of Defense

NSFNET (National Science Foundation Network) was created to link supercomputers for research

Each of these were

largescale

, packet-switching networks that led to the creation of the Internet

ARPANET

NSFNETSlide45

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NETWORK TYPESInternet ApplicationsSlide46

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NETWORK TYPES6. Internet2Not-for-profit consortium made up of over 200 universities, as well as industry and government partners, to develop and deploy advanced network applications and technologies for research and commercial purposes

Goals

Create a leading-edge network capability for the national research community

Enable revolutionary Internet applications based on a much higher-performance Internet than we have today

Ensure the rapid transfer of new network services and applications to the broader Internet communitySlide47

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NETWORKING PROTOCOLSNetwork ProtocolsAn agreed-upon set of rules or conventions governing communication among elements of a network

Open Systems Interconnection (OSI) Reference Model

Skeleton for standards developed by International Organization for Standardization (ISO)

Conceptual framework to understand how communications in networks take place

Figure 3.11Slide48

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NETWORKING PROTOCOLSTransmission Control Protocol/Internet Protocol (TCP/IP)Created to link different types of networks (e.g., satellite and ground packet networks) together into a network of networksHas become de facto

standard protocol for networking

-TCP is responsible for the reliable and ordered transmission of messages

- IP is responsible for routing individual packets based on their individual addresses (IP addresses)

Roughly corresponds to network and transport layers of OSI modelSlide49

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NETWORKNG HAS BECOME CRITICAL TO DO BUSINESSNetworking and Telecommunications have become necessary for businesses to functionIncreasing access to the Internet in developing countries due to new lines being funded by private and public organizations

Impact of cut Internet cables

in Middle

East

- 2008Slide50

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CopyrightAll rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher. Printed in the United States of America.

Publishing as Prentice Hall