Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 6-1 Introduction to Information Technology 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. Chapter 6: Telecommunications and Networks Prepared by: Roberta M. Roth, Ph.D. University of Northern Iowa

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 6-2 Chapter Preview  In this chapter, we will study:  The basic components of a telecomm system  The technologies used in telecomm systems  Various ways to configure networks  Various ways that businesses use networks today

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 6-3 The Telecommunications System  The hardware and software that transmits information from one location to another  Components include:  Hardware  Media  Networks  Software  Data comm providers  Protocols  Applications

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 6-4 Telecommunication Signals  Analog signals  Continuous waves  Information conveyed by changing wave characteristics (amplitude and frequency)  Digital signals  Discrete pulses  Information conveyed in binary form (on or off pulses)  Easily understood by computer

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 6-5 Communication Processors  Hardware devices utilized in data transmission and reception  Modem - device that converts analog signals to digital (and vice versa); enables signal transmission over telephone system  Multiplexor - device that transmits multiple signals over single medium  Front-end processor – specialized computer dedicated to managing communication tasks

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 6-6 Wire-based Communication Channels  Twisted-pair wire (telephone wire)  Cheap and easy to work with  Slow; subject to interference; low security  Coaxial cable  Carries more data; shielded from interference  More expensive; harder to work with; low security

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 6-7 Wire-based Communication Channels (continued)  Fiber-optic cable  Transmit information as light waves through glass fiber  Fast; high-capacity; secure; not subject to interference  Hard to work with

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 6-8 Wireless Communication Channels  Microwave  High capacity; inexpensive relative to wire  Requires line of sight transmission towers; subject to environmental interference  Satellite  Very high capacity; large coverage area  Expensive; propagation delay; requires encryption for security

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 6-9 Wireless Communication Channels (continued)  Radio  Suitable for short distance communication; inexpensive; easy to install; high speed  Interference problems; insecure  Cellular radio technology  Infrared

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc Understanding Communication Media  Transmission speed  Bandwidth – the range of frequencies available in a channel  More bandwidth, more channel capacity  Transmission mode  Character by character (asynchronous)  Streams of characters (synchronous)  Transmission accuracy  Accuracy controls added to messages  Error detection and correction required

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc Telecomm Carriers and Services  Telecomm carriers – provide telecomm technology and services for data communication  Common carriers – long-distance phone companies  Value-added carriers – provide private telecomm systems and services for a fee

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc Telecomm Carriers and Services (continued)  Telecomm services  Switched lines – transmission is routed along path to destination  Dedicated lines – continuous connection is established  Wide-area Telecomm Service (WATS) – lower cost long distance telephone service  Integrated Services Digital Network (ISDN) – high speed data transmission over existing phone lines  Digital Subscriber Lines (DSL) - high speed digital transmission over existing phone lines

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc Network Basics  Network – the communication devices, media, and software needed to connect two or more computer systems.  Local area networks (LANs) – a network that spans a relatively small geographic distance  Wide area networks (WANs) – network that spans a large geographic distance

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc Local Area Networks  Connect computers and other devices enabling resource sharing  Variety of topologies can be used, each with performance strengths and weaknesses  Several LANs can be connected via bridges  LANs can be connected to external networks via gateways

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc LAN Basics  Required technology:  Cables or wireless technology  Network interface adaptor cards  Network management software  Chosen topology is implemented by selection of software, interface cards, and wiring strategy.

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc Wide Area Networks  Service provided by common carriers  Internet is a public WAN  Value-added networks (VAN) – private, data-only networks managed by third party; accessed via subscription.  Virtual private network (VPN) – secure gateway between corporate systems and the Internet.

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc Network Communication Software  Needed to provide a number of network functions:  Check for errors  Format messages  Maintain communication logs  Ensure data security and privacy  Provide message translation

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc Network Communication Software (continued)  Components  Network Operating System – enables all devices on network to communicate  Network Management Software – simplifies human network management tasks  Protocols – specify rules that govern device communication over the network

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc Network Communication Software (continued)  Types of Protocols  Ethernet Most common protocol May be 10BaseT (10 Mbps); Fast Ethernet 100BaseT (100Mbps); Gigabit Ethernet (1Gbps)  Transmission Control Protocol/Internet Protocol (TCP-IP) Sends large files accurately over different systems Standard of the Internet

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc Network Communication Software (continued)  Data Transmission Options to improve network performance  Packet-switching  Frame relay  Fiber Distributed Data Interface (FDDI)  Asynchronous Transfer Mode (ATM)  Switched Hub Technologies  Synchronous Optical Network (SONET)  T-carrier System

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc Network Processing Strategies  IS managers strive to provide good network response time and network availability  Distributed processing enables computers in various locations to communicate over telecomm links  Terminal-to-host processing  File server processing  Client/server architecture and processing

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc Network Processing Strategies (continued)  Client/server processing  Applications can be divided into presentation, applications, and data management components  Components can be partitioned between the server and the clients to form different implementations

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc Network Processing Strategies (continued)  Peer-to-peer processing  Simplified form of client/server  Devices attached to network have access to all other devices  No file server involved  Simple set up and maintenance  Implemented in many operating systems such as Windows 2000 and Windows XP

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc Network Processing Strategies (continued)  Open Systems – ideal not fully achieved  Any device can be seamlessly connected to any other device, regardless of size, operating system, or application  Connectivity – ability of computer resources to communicate without human intervention  Enterprise-wide network – spans entire organization because of open systems and connectivity

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc Telecomm Applications  Electronic Mail – computer- based messaging  Videoconferencing – group meetings between separate locations  Electronic Data Interchange – electronic transmission of routine business transactions  Electronic Funds Transfer – electronic processing of financial transactions  Facsimiles – electronic document transmittal  Telecommuting – working at home via telecomm links  Distance Learning – classes offered on same time/different place, or different time/ different place basis  Telematics

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc Chapter Summary  Components of a telecomm system  Types of communication media used in telecomm systems  Types of networks  Ways to organize network processing  Ways to utilize networks in businesses today

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