E. Wainright Martin Carol V. Brown Daniel W. DeHayes Jeffrey A. Hoffer William C. Perkins MANAGINGINFORMATIONTECHNOLOGY FIFTH EDITION CHAPTER 4 TELECOMMUNICATIONS AND NETWORKING

© 2005 Pearson Prentice-Hall Chapter Sharing of technology resources Sharing of data Distributed data processing and client/server systems Enhanced communications Marketing outreach T HE N EED FOR N ETWORKING Page 96-97

© 2005 Pearson Prentice-Hall Chapter A N O VERVIEW OF T ELECOMMUNICATIONS AND N ETWORKING Page Networking – the electronic linking of geographically dispersed devices Telecommunications – communications (voice and data) at a distance

© 2005 Pearson Prentice-Hall Chapter Page 98 Table 4.1 Functions of a Telecommunications Network

© 2005 Pearson Prentice-Hall Chapter K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING Analog and Digital Signals Page Analog network uses continuous voltage varying as a function of time  Example: voice over telephone lines Digital network directly transmits two discrete states  Note: 0 for pulse off and 1 for pulse on

© 2005 Pearson Prentice-Hall Chapter K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING Analog and Digital Signals Page 99 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 Analog and Digital Signals Page 99 Figure 4.1 Use of Modem in Analog Network K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING

© 2005 Pearson Prentice-Hall Chapter K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING Speed of Transmission Page 100 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 K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING Speed of Transmission Page 100 Hertz – cycles per second Baud – number of signals sent per second Bits per second (bps) – number of bits sent per second When each cycle sends one signal that transmits exactly one bit of data (often the case), then the three terms are identical Note:

© 2005 Pearson Prentice-Hall Chapter K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING Types of Transmission Lines Page 101 Switched line system  Example: public telephone system  Uses switching centers to route signals along best possible path to destination 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 K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING Types of Transmission Lines Page 101 Simplex – data travels in one direction only Half-duplex – data can travel in both directions, but only one direction at a time Full-duplex – data travels in both directions at the same time

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

© 2005 Pearson Prentice-Hall Chapter Transmission Media Page 101 KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Typical Speeds Table 4.2 Telecommunications Transmission Speeds

© 2005 Pearson Prentice-Hall Chapter Transmission Media Page 102 KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Figure 4.3 Construction of a Coaxial Cable

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

© 2005 Pearson Prentice-Hall Chapter Transmission Media Page 102 KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Figure 4.4 Satellite Communications

© 2005 Pearson Prentice-Hall Chapter K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING Types of Transmission Lines Page 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 K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING Topology of Networks Page 106 Topology – term used to describe the configuration or arrangement of network devices and media

© 2005 Pearson Prentice-Hall Chapter Topology of Networks Page 106 KEY ELEMENTS OF TELECOMMUNICATIONS AND NETWORKING Figure 4.5 Network Topologies

© 2005 Pearson Prentice-Hall Chapter More Complex Networks Page 107 Figure 4.6 vBNS+ Network Map

© 2005 Pearson Prentice-Hall Chapter K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING Types of Networks Page 108 Computer Telecommunications Networks Private branch exchange (PBX) Networks Local Area Networks (LANs) Backbone Networks Wide Area Networks (WANs) Internet Internet2

© 2005 Pearson Prentice-Hall Chapter K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING Types of Networks Page 108 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 Page 108 Figure 4.7 Computer Telecommunications Network

© 2005 Pearson Prentice-Hall Chapter K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING Types of Networks Page 109 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 K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING Types of Networks Page 109 Private Branch Exchanges (PBX)  Advantages: Can connect ALL telecommunications devices in a building or campus Can use existing telephone wiring Can carry voice and data over same network Has a high-potential throughput

© 2005 Pearson Prentice-Hall Chapter Page 109 Figure 4.8 Schematic Representation of a PBX

© 2005 Pearson Prentice-Hall Chapter K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING Types of Networks Page 109 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 K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING Page 109 LAN Topologies and Standards  Contention bus design … IEEE  Token bus design … IEEE  Token ring design … IEEE  Wireless design … IEEE Local Area Networks

© 2005 Pearson Prentice-Hall Chapter K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING Local Area Networks Page 110 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 Page 109 Figure 4.9 Shared Ethernet Topology: Logical Bus, Physical Star

© 2005 Pearson Prentice-Hall Chapter K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING Page 110 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 Local Area Networks

© 2005 Pearson Prentice-Hall Chapter K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING Page 110 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 Local Area Networks

© 2005 Pearson Prentice-Hall Chapter K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING Page 111 Token Ring  Device attached to ring must seize token before can send a message  Collisions cannot occur  Usual implementation is physical star, logical ring Local Area Networks

© 2005 Pearson Prentice-Hall Chapter K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING Page 111 Wireless LAN  Known as Wi-Fi (wireless fidelity)  Growing in demand for corporate and home use  Use IEEE standards with shared Ethernet design  Requires use of wireless network interface card (NIC)  Wireless Access Point (WAP) – radio transceiver that acts as a hub Local Area Networks

© 2005 Pearson Prentice-Hall Chapter Page 112 Figure 4.10 Wireless Local Area Network Topology

© 2005 Pearson Prentice-Hall Chapter K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING Types of Networks Page 113 Backbone Network In-between network that interconnects LANs in a single organization with each other and with organization’s WAN and the Internet

The backbone.

Figure 2.16 Packet switching.

© 2005 Pearson Prentice-Hall Chapter K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING Types of Networks Page 113 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 Page 112 Figure 4.11 Sample Backbone Network

© 2005 Pearson Prentice-Hall Chapter K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING Types of Networks Page 114 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 K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING Types of WANs Page 115  Switched-circuit Direct distance dialing (DDD) Wide Area Telephone Service (WATS) Integrated Service Digital Network (ISDN)  Dedicated-circuit Leased lines Satellite

© 2005 Pearson Prentice-Hall Chapter K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING Page 116  Packet-switched Shared private lines using store-and-forward data transmission Permits multiple connections to exist simultaneously over the same physical circuit Types of WANs

© 2005 Pearson Prentice-Hall Chapter K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING Page 117  ATM – fast packet switching with short, fixed-length packets  Virtual Private Networks (VPNs) – provide same as private packet-switched network using the public Internet Types of WANs

© 2005 Pearson Prentice-Hall Chapter K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING Types of Networks Page 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: Electronic mail Remote login Discussion groups Sharing of data resources

© 2005 Pearson Prentice-Hall Chapter Page 118 Table 4.4 Internet Applications

© 2005 Pearson Prentice-Hall Chapter K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING DSL, Cable Modem, and Satellite Page 120 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 K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING Intranets Page 122 Intranet – a network operating within an organization that uses the TCP/IP protocol

Intranet, Extranet, and VPN Technologies

© 2005 Pearson Prentice-Hall Chapter K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING Page 122 Internet2 – 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 K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING Page 123 Primary goals of Internet2:  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 K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING Network Protocols Page 124 Protocol – agreed-upon set of rules governing communication among layers or levels of a network

© 2005 Pearson Prentice-Hall Chapter K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING Page 124 LAN protocols:  Contention bus  Token bus  Token ring  Wireless IBM’s own protocol – Systems Network Architecture (SNA) Network Protocols

© 2005 Pearson Prentice-Hall Chapter K EY E LEMENTS OF T ELECOMMUNICATIONS AND N ETWORKING Page International Organization for Standardization (ISO) network protocol – Open Systems Interconnection Reference Model (OSI)  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 Network Protocols

The TCP/IP Protocol Suite

Using TCP/IP protocols to download a page.

© 2005 Pearson Prentice-Hall Chapter Page 126 Figure 4.17 Data Transmission Based on OSI Model

© 2005 Pearson Prentice-Hall Chapter T HE E XPLODING R OLE OF T ELECOMMUNICATIONS AND N ETWORKING Page Online Operations Connectivity Electronic Data Interchange (EDI) and Electronic Commerce Marketing

© 2005 Pearson Prentice-Hall Chapter T HE T ELECOMMUNICATIONS I NDUSTRY Carriers  Own or lease the physical plant – cabling, satellites, cellular towers, etc.  Sell service of transmitting communication from one location to another Page 130

© 2005 Pearson Prentice-Hall Chapter T HE T ELECOMMUNICATIONS I NDUSTRY Equipment vendors  Manufacture and sell LAN software and hardware  Includes routers, hubs, wireless access points, digital switches, multiplexers, cellular telephones, modems Page 130

© 2005 Pearson Prentice-Hall Chapter T HE T ELECOMMUNICATIONS I NDUSTRY Page 130 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