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  • Copyright 2005 John Wiley & Sons, Inc1 - *Chapter 1

    Introduction to Data Communications

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *OutlineBrief historyCommunications, Information Systems and the Internet Data Communications NetworksNetwork components, network typesNetwork ModelsOSI model, Internet model, LayersNetwork StandardsStandards making, common standardsFuture TrendsPervasive networking, integration of voice, video, and data, new information services

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *Information AgeFirst Industrial RevolutionIntroduction of machineryNew organizational methodsChanged the way people workedSecond Industrial Revolution Information AgeIntroduction of computersIntroduction of networking and data communicationChanged the way people worked againFaster communication Collapsing Information lagBrought people together Globalization

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *Collapsing Information Laghuge quantities of information transmitted in a fraction of a second.telegraphInformation took days or weeks to be transmittedInformation transmitted in minutes or hoursElectronic communicationssped up the rate of transmission of information,growth of telecommunications and especially computer networksglobalization phenomenon (WWW)

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *Three Faces of NetworkingFundamental concepts of networkingHow data moves from one computer to another over a networkTheories of how network operateTechnologies in use todayHow theories are implemented, specific productsHow do they work, their use, applicationsManagement of networking technologiesSecurityNetwork DesignManaging the network

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *Advances in Phone Technology

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *Invention to Regulation

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *1984 Consent Decree Divestiture: AT&T broken up into a long distance company (AT&T) & 7 Regional Bell Operating Companies (RBOCs)Deregulation:Competitive long distance (IXC) market; MCI & Sprint enter LD market (among others)Local Exchange Carrier (LEC) service markets remained under RBOC monopoly

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *US Telecom Act of 1996Replaced all current laws, FCC regulations, 1984 consent decree, and overrules state lawsMain goal: open local markets to competitionTo date, though, local competition slow to take holdLarge IXCs expected to move into the local markets, happening only recentlyLikewise, RBOCs expected to move into long distance markets, happening only recently

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *Worldwide Competitive MarketsInternet marketExtremely competitive with more than 5000 Internet Service Providers (ISPs) in the US alone. Heavy competition in this area may lead to a shake out in the near future.World Trade Organization (WTO) agreement (1997)commitments by 68 countries to open, deregulate or lessen regulation in their telecom marketsMulti-national telecom companiesUS companies offering services in Europe, South AmericaEuropean companies offering services in USA

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *History of Information Systems

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *Internet Milestones

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *Datacom BasicsBroadband CommunicationsTelecommunicationstransmission of voice, video, data, imply longer distances- broader termData Communicationsmovement of computer information by means of electrical or optical transmission systemsconvergence

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *Print ServerWeb ServerFile ServerPrinterHUBRouterClient ComputersTo other networks(e.g., Internet)Components of a Local Area NetworkServersCircuits

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *Network Types (based on Scale) Local Area Networks (LANs) - room, buildinga group of PCs that share a circuit.Backbone Networks - less than few kmsa high speed backbone linking the LANs at various locations.Metropolitan Area Networks (MAN) - (< few 10 kms)connects LANs and BNs at different locations leased lines or other services used to transmit data.Wide Area Networks (WANs) - (> few 10 kms)Same as MAN except wider scale

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *LAN vs. BN vs. MAN vs. WAN Figure 1.2 goes here

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *Intranet vs. Extranet IntranetA LAN that uses the Internet technologiesOpen only those inside the organizationExample: insurance related information provided to employees over an intranetExtranetA LAN that uses the Internet technologiesOpen only those invited users outside the organizationAccessible through the InternetExample: Suppliers and customers accessing inventory information in a company over an extranet

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *Implementation of Communications Functions

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *Multi-layer Network ModelsThe two most important such network models: OSI and InternetOpen Systems Interconnection ModelCreated by International Standards Organization (ISO) as a framework for computer network standards in 1984Based on 7 layersInternet ModelCreated by DARPA originally in early 70sDeveloped to solve to the problem of internetworkingBased on 5 layersBased on Transmission Control Protocol/ Internet Protocol (TCP/IP) suite

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *7-Layer Model of OSI

    Application Layerset of utilities used by application programs Presentation Layerformats data for presentation to the userprovides data interfaces, data compression and translation between different data formatsSession Layerinitiates, maintains and terminates each logical session between sender and receiverPlease Do Not Touch Steves Pet AlligatorPhysical DataLink Network Transport Session Presentation Application

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *7-Layer Model of OSITransport Layerdeals with end-to-end issues such as segmenting the message for network transport, and maintaining the logical connections between sender and receiverNetwork Layerresponsible for making routing decisionsData Link Layerdeals with message delineation, error control and network medium access controlPhysical Layerdefines how individual bits are formatted to be transmitted through the network

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *Internets 5-Layer Model

    Application Layerused by application program Transport Layer responsible for establishing end-to-end connections, translates domain names into numeric addresses and segments messagesNetwork Layer - same as in OSI modelData Link Layer - same as in OSI modelPhysical Layer - same as in OSI model*Please Do Not Touch AlligatorPhysical DataLink Network Transport Application

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *Comparison of Network Models

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *Message Transmission Using LayerssenderreceiverA receiving layer wraps incoming message with an envelope Adds layer related addressing informationA receiving layer removes the layer related envelope and forwards the message up

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *ProtocolsUsed by Network model layersSets of rules to define how to communicate at each layer and how to interface with adjacent layers

    receiversenderLayer NLayer N-1Layer N+1Layer NLayer N-1Layer N+1

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *Message Transmission Example

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *Important Points to ObserveMany different software packages (protocols) and many different packets (at different layers)Easy to develop new softwareSimple to change the software at any levelMatching layers communicate at different computersAccomplished by standardse.g., Physical layer at the sending computer must be the same in the receiving computerSomewhat inefficientInvolves many software layers and packet typesPacket overhead (slower transmission, processing time)

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *StandardsImportanceProvide a fixed way for hardware and/or software systems (different companies) to communicateHelp promote competition and decrease the price Types of StandardsFormal standards Developed by an industry or government standards-making bodyDe-facto standards Emerge in the marketplace and widely usedLack official backing by a standards-making body

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *Standardization ProcessesSpecificationDeveloping the nomenclature and identifying the problems to be addressedIdentification of choicesIdentifying solutions to the problems and choose the optimum solutionAcceptanceDefining the solution, getting it recognized by industry so that a uniform solution is accepted

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *Major Standards BodiesISO (International Organization for Standardization) Technical recommendations for data communication interfacesComposed of each countrys national standards orgs.Based in Geneva, Switzerland (www.iso.ch)ITU-T (International Telecommunications Union Telecom Group Technical recommendations about telephone, telegraph and data communications interfaces Composed of representatives from each country in UNBased in Geneva, Switzerland (www.itu.int)

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *Major Standards Bodies (Cont.)ANSI (American National Standards Institute)Coordinating organization for US (not a standards- making body)www.ansi.orgIEEE (Institute of Electrical and Electronic Engineers)Professional society; also develops mostly LAN standardsstandards.ieee.orgIETF (Internet Engineering Task Force) Develops Internet standardsNo official membership (anyone welcomes)www.ietf.org

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *Some Data Comm. Standards

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *Emerging Trends in NetworkingPervasive NetworkingIntegration of Voice, Video and DataNew Information Services

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *Pervasive NetworkingMeans Network access everywhereExponential growth of Network useMany new types of devices will have network capabilityExponential growth of data rates for all kinds of networkingBroadband communicationsUse circuits with 1 Mbps or higher (e.g., DSL)

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *Relative Capacities of Telephone, LAN, BN, WAN, and Internet Circuits.

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *Integration of Voice, Video & DataAlso called ConvergenceNetworks that were previously transmitted using separate networks will merge into a single, high speed, multimedia network in the near futureFirst step (already underway)Integration of voice and data Next Step Video merging with voice and data Will take longer partly due to the high data rates required for video

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *New Information ServicesWorld Wide Web basedMany new types of information services becoming availableServices that help ensure quality of information received over wwwApplication Service Providers (ASPs)Develop specific systems for companiesProviding and operating a payroll system for a company that does not have one of its ownInformation Utilities (Future of ASPs)Providing a wide range of info services (email, web, payroll, etc.) (similar to electric or water utilities)

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *Implications for ManagementEmbrace change and actively seek to apply networks to improve what you doInformation moved quickly and easily anywhere and anytimeInformation accessed by customers and competitors globallyUse a set of industry standard technologiesCan easily mix and match equipment from different vendorsEasier to migrate from older technologies to newer technologiesSmaller cost by using a few well known standards

    Copyright 2005 John Wiley & Sons, Inc

  • Copyright 2005 John Wiley & Sons, Inc1 - *Copyright 2005 John Wiley & Sons, Inc.All rights reserved. Reproduction or translation of this work beyond that permitted in section 117 of the 1976 United States Copyright Act without express permission of the copyright owner is unlawful. Request for further information should be addressed to the Permissions Department, John Wiley & Sons, Inc. The purchaser may make back-up copies for his/her own use only and not for distribution or resale. The Publisher assumes no responsibility for errors, omissions, or damages caused by the use of these programs or from the use of the information herein.

    Copyright 2005 John Wiley & Sons, Inc

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