MANAGING INFORMATION TECHNOLOGY FIFTH EDITION CHAPTER 4 TELECOMMUNICATIONS

MANAGING INFORMATION TECHNOLOGY FIFTH EDITION CHAPTER 4 TELECOMMUNICATIONS AND NETWORKING E. Wainright Martin Carol V. Brown Daniel W. De. Hayes Jeffrey A. Hoffer William C. Perkins

THE NEED FOR NETWORKING n Sharing of technology resources n Sharing of data n Distributed data processing and client/server systems n Enhanced communications n Marketing outreach © 2005 Pearson Prentice-Hall Chapter 4 - 2 2 Page 96 -97

AN OVERVIEW OF TELECOMMUNICATIONS AND NETWORKING Networking – the electronic linking of geographically dispersed devices Telecommunications – communications (voice and data) at a distance © 2005 Pearson Prentice-Hall Chapter 4 - 3 3 Page 97 -98

© 2005 Pearson Prentice-Hall Chapter 4 - 4 Table 4. 1 Functions of a Telecommunications Network 4 Page 98

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Analog and Digital Signals n Analog network uses continuous voltage varying as a function of time Example: voice over telephone lines n Digital network directly transmits two discrete states Note: 0 for pulse off and 1 for pulse on © 2005 Pearson Prentice-Hall Chapter 4 - 5 5 Page 98 -100

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Analog and Digital Signals n Modem Device needed when transmitting data over analog lines Converts data from digital to analog to be sent over analog telephone lines Also reconverts data back to digital after data transmission Abbreviation for modulator/demodulator © 2005 Pearson Prentice-Hall Chapter 4 - 6 6 Page 99

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Analog and Digital Signals © 2005 Pearson Prentice-Hall Chapter 4 - 7 Figure 4. 1 Use of Modem in Analog Network 7 Page 99

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Speed of Transmission Bandwidth – • difference between highest and lowest frequencies (cycles per second) that can be transmitted on a single medium • common measure of a medium’s capacity © 2005 Pearson Prentice-Hall Chapter 4 - 8 8 Page 100

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Speed of Transmission n Hertz – cycles per second n Baud – number of signals sent per second n Bits per second (bps) – number of bits sent per second : Note. When each cycle sends one signal that transmits exactly one bit of data (often the case), then the three terms are identical © 2005 Pearson Prentice-Hall Chapter 4 - 9 9 Page 100

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Types of Transmission Lines n Switched line system Example: public telephone system Uses switching centers to route signals along best possible path to destination n Private (dedicated) lines Leased from companies such as MCI, Sprint, AT&T Use direct physical lines between source and destination © 2005 Pearson Prentice-Hall Chapter 4 - 10 10 Page 101

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Types of Transmission Lines n Simplex – data travels in one direction only n Half-duplex – data can travel in both directions, but only one direction at a time n Full-duplex – data travels in both directions at the same time © 2005 Pearson Prentice-Hall Chapter 4 - 11 11 Page 101

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Transmission Media © 2005 Pearson Prentice-Hall Chapter 4 - 12 12 Page 101

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Transmission Media © 2005 Pearson Prentice-Hall Chapter 4 - 13 Typical Speeds Table 4. 2 Telecommunications Transmission Speeds 13 Page 101

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Transmission Media © 2005 Pearson Prentice-Hall Chapter 4 - 14 14 Figure 4. 3 Construction of a Coaxial Cable Page 102

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Transmission Media Wireless – broadcast technology in which radio signals are sent out into the air n Cordless telephone n Microwave n Cellular phone n Satellite n Wireless LAN © 2005 Pearson Prentice-Hall Chapter 4 - 15 15 Page 102

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Transmission Media © 2005 Pearson Prentice-Hall Chapter 4 - 16 Figure 4. 4 Satellite Communications 16 Page 102

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Types of Transmission Lines n Fiber-optic cabling Newest transmission medium Transmits data by pulses of light through thin fiber of glass Much faster than other media Thinner … requires less space More secure … harder to tap © 2005 Pearson Prentice-Hall Chapter 4 - 17 Page 105 -106 17

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Topology of Networks Topology – term used to describe the configuration or arrangement of network devices and media © 2005 Pearson Prentice-Hall Chapter 4 - 18 18 Page 106

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Topology of Networks © 2005 Pearson Prentice-Hall Chapter 4 - 19 19 Page 106 Figure 4. 5 Network Topologies

More Complex Networks © 2005 Pearson Prentice-Hall Chapter 4 - 20 Figure 4. 6 v. BNS+ Network Map 20 Page 107

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Types of Networks n Computer Telecommunications Networks n Private branch exchange (PBX) Networks n Local Area Networks (LANs) n Backbone Networks n Wide Area Networks (WANs) n Internet 2 © 2005 Pearson Prentice-Hall Chapter 4 - 21 21 Page 108

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Types of Networks n Computer Telecommunications Networks Emanates from a single medium or large computer Usually arranged as a tree Uses coaxial and twisted pair cabling Controlled by central computer Often has a front-end processor to handle all aspects of telecommunications © 2005 Pearson Prentice-Hall Chapter 4 - 22 22 Page 108

© 2005 Pearson Prentice-Hall Chapter 4 - 23 Figure 4. 7 Computer 23 Telecommunications Network Page 108

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Types of Networks n Private Branch Exchanges (PBX) Originally analog, today usually digital Can serve as the central device in a star or ring network Can function as front-end processor for mainframe © 2005 Pearson Prentice-Hall Chapter 4 - 24 24 Page 109

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Types of Networks n Private Branch Exchanges (PBX) Advantages: ü Can connect ALL telecommunications devices in a building or campus ü Can use existing telephone wiring ü Can carry voice and data over same network ü Has a high-potential throughput © 2005 Pearson Prentice-Hall Chapter 4 - 25 25 Page 109

© 2005 Pearson Prentice-Hall Chapter 4 - 26 Figure 4. 8 Schematic Representation of a PBX 26 Page 109

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Types of Networks n Local Area Networks Owned by a single organization Operate within area 2 -3 miles in diameter Contain a number of intelligent devices, usually microcomputers, that can process data … based on peer-to-peer relationship No part of telephone system, have their own wiring © 2005 Pearson Prentice-Hall Chapter 4 - 27 27 Page 109

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Local Area Networks n LAN Topologies and Standards Contention bus design … IEEE 802. 3 Token bus design … IEEE 802. 4 Token ring design … IEEE 802. 5 Wireless design … IEEE 802. 11 © 2005 Pearson Prentice-Hall Chapter 4 - 28 28 Page 109

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Local Area Networks n Contention Bus Design (Ethernet) Bus topology Implemented with coax or twisted pair Usually half-duplex All devices contend for use of cable Design now called Shared Ethernet … uses a contention bus as its logical topology and implemented with a physical star arrangement … © 2005 Pearson Prentice-Hall Chapter 4 - 29 29 Page 110

© 2005 Pearson Prentice-Hall Chapter 4 - 30 Figure 4. 9 Shared Ethernet Topology: Logical Bus, Physical Star 30 Page 109

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Local Area Networks n Switched Ethernet Newer variation, better performance, higher price Uses switch instead of hub Operates both logical and physical star Each device has own dedicated circuit © 2005 Pearson Prentice-Hall Chapter 4 - 31 31 Page 110

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Local Area Networks n Token Bus Employs bus topology, no contention Uses single token passed around to all devices in order Device can only transmit when has token Central to Manufacturing Automation Protocol (MAP) – connects robots and other machines on assembly line by a LAN © 2005 Pearson Prentice-Hall Chapter 4 - 32 32 Page 110

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Local Area Networks n Token Ring Device attached to ring must seize token before can send a message Collisions cannot occur Usual implementation is physical star, logical ring © 2005 Pearson Prentice-Hall Chapter 4 - 33 33 Page 111

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Local Area Networks n Wireless LAN Known as Wi-Fi (wireless fidelity) Growing in demand for corporate and home use Use IEEE 802. 11 standards with shared Ethernet design Requires use of wireless network interface card (NIC) Wireless Access Point (WAP) – radio transceiver that acts as a hub © 2005 Pearson Prentice-Hall Chapter 4 - 34 34 Page 111

© 2005 Pearson Prentice-Hall Chapter 4 - 35 Figure 4. 10 Wireless Local Area Network 35 Topology Page 112

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Types of Networks n Backbone Network In-between network that interconnects LANs in a single organization with each other and with organization’s WAN and the Internet © 2005 Pearson Prentice-Hall Chapter 4 - 36 36 Page 113

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Types of Networks n Backbone network terminology: Bridge – connects two LANs using same protocol Router (gateway) – connects two or more LANs that may use different protocols Switch – connects more than two LANs using the same protocols © 2005 Pearson Prentice-Hall Chapter 4 - 37 37 Page 113

© 2005 Pearson Prentice-Hall Chapter 4 - 38 Figure 4. 11 Sample Backbone Network 38 Page 112

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Types of Networks n Wide Area Networks (WANs) Communicate voice and data across greater distances Usually owned by several organizations (including user organization and common carrier) Employ point-to-point transmission Often rely on public telephone network © 2005 Pearson Prentice-Hall Chapter 4 - 39 39 Page 114

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Types of WANs Switched-circuit ü Direct distance dialing (DDD) ü Wide Area Telephone Service (WATS) ü Integrated Service Digital Network (ISDN) Dedicated-circuit ü Leased lines ü Satellite © 2005 Pearson Prentice-Hall Chapter 4 - 40 40 Page 115

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Types of WANs Packet-switched ü Shared private lines using store-and-forward data transmission ü Permits multiple connections to exist simultaneously over the same physical circuit © 2005 Pearson Prentice-Hall Chapter 4 - 41 41 Page 116

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Types of WANs ATM – fast packet switching with short, fixed-length packets Virtual Private Networks (VPNs) – provide same as private packet-switched network using the public Internet © 2005 Pearson Prentice-Hall Chapter 4 - 42 42 Page 117

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Types of Networks n The Internet Network of networks that use the TCP/IP protocol Contain gateways to computers that do not use TCP/IP Provides four basic functions: ü ü © 2005 Pearson Prentice-Hall Electronic mail Remote login Discussion groups Sharing of data resources Chapter 4 - 43 Page 117 -118 43

© 2005 Pearson Prentice-Hall Chapter 4 - 44 Table 4. 4 Internet Applications 44 Page 118

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING DSL, Cable Modem, and Satellite n Internet access services: Digital subscriber line (DSL) – service offered by telephone companies using copper wire already installed in homes … moving data over wires without disturbing voice traffic Cable modem – connection obtained from cable TV company using existing home coaxial cable Satellite – most expensive, but may be only option for customers in rural areas © 2005 Pearson Prentice-Hall Chapter 4 - 45 45 Page 120

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Intranets Intranet – a network operating within an organization that uses the TCP/IP protocol © 2005 Pearson Prentice-Hall Chapter 4 - 46 46 Page 122

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Internet 2 – not-for-profit consortium of over 200 universities, working with over 60 technology companies and the U. S. government, to develop and deploy advanced network applications and technologies © 2005 Pearson Prentice-Hall Chapter 4 - 47 47 Page 122

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING n Primary goals of Internet 2: Create a leading-edge network capability for the national research community Enable revolutionary Internet applications based on a much higher-performance Internet that we have today Ensure the rapid transfer of new network services and applications to the broader Internet community © 2005 Pearson Prentice-Hall Chapter 4 - 48 48 Page 123

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Network Protocols Protocol – agreed-upon set of rules governing communication among layers or levels of a network © 2005 Pearson Prentice-Hall Chapter 4 - 49 49 Page 124

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Network Protocols n LAN protocols: n Contention bus Token ring Wireless IBM’s own protocol – Systems Network Architecture (SNA) © 2005 Pearson Prentice-Hall Chapter 4 - 50 50 Page 124

KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Network Protocols n International Organization for Standardization (ISO) network protocol – Open Systems Interconnection Reference Model (OSI) n Thought to become the only standard for networking Gained momentum until Internet explosion Transmission Control Protocol/Internet Protocol (TCP/IP) Has become the de facto standard for networking today © 2005 Pearson Prentice-Hall Chapter 4 - 51 Page 124 -125 51

© 2005 Pearson Prentice-Hall Chapter 4 - 52 Figure 4. 17 Data Transmission Based on OSI Model 52 Page 126

THE EXPLODING ROLE OF TELECOMMUNICATIONS AND NETWORKING n Online Operations n Connectivity n Electronic Data Interchange (EDI) and Electronic Commerce n Marketing © 2005 Pearson Prentice-Hall Chapter 4 - 53 Page 128 -129 53

THE TELECOMMUNICATIONS INDUSTRY n Carriers Own or lease the physical plant – cabling, satellites, cellular towers, etc. Sell service of transmitting communication from one location to another © 2005 Pearson Prentice-Hall Chapter 4 - 54 54 Page 130

THE TELECOMMUNICATIONS INDUSTRY n Equipment vendors Manufacture and sell LAN software and hardware Includes routers, hubs, wireless access points, digital switches, multiplexers, cellular telephones, modems © 2005 Pearson Prentice-Hall Chapter 4 - 55 55 Page 130

THE TELECOMMUNICATIONS INDUSTRY n Service providers Operate networks and deliver services through the network Provide access to or services via the Internet (such as AOL, Microsoft Network, Yahoo!, and many ISPs © 2005 Pearson Prentice-Hall Chapter 4 - 56 56 Page 130