Business Data Communications and Networking - Chapter 1: Introduction to Data Communications

Business Data Communications and Networking 8th Edition Jerry Fitzgerald and Alan DennisJohn Wiley & Sons, Inc Prof. M. UlemaManhattan CollegeComputer Information Systems1Copyright 2005 John Wiley & Sons, IncChapter 1Introduction to Data Communications2Copyright 2005 John Wiley & Sons, IncOutlineBrief 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 services3Copyright 2005 John Wiley & Sons, IncInformation 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  Globalization4Copyright 2005 John Wiley & Sons, IncCollapsing Information Lag1900195020041850 huge 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)5Copyright 2005 John Wiley & Sons, IncThree 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 network6Copyright 2005 John Wiley & Sons, IncAdvances in Phone Technology1876Phone inventedfirst trans-continental and transatlantic phone connections19151919Strowger (stepper) switch, rotary dial phones(enabling automatic connections)1948Microwave trunk lines (Canada)1962Telstar (Telecommunications via satellite), Fax services, digital transmission (T-carriers)1969Picturefone (failed commercially)1976Packet-switched data communications1984Cellular telephone7Copyright 2005 John Wiley & Sons, IncInvention to Regulation1900millions of phones in use in the USRegulation began in the USA (ICC)1934FCC established1968Carterfone court decision allowing non-Bell CPE1970MCI wins court case; begins providing some long distance services1984Consent decree by US federal court 1996US Telecom Act A time for technological change1885AT&TPhone invented (rapid acceptance)1876Bell System: de facto monopoly19108Copyright 2005 John Wiley & Sons, Inc1984 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 monopoly9Copyright 2005 John Wiley & Sons, IncUS 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 recently10Copyright 2005 John Wiley & Sons, IncWorldwide 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 USA11Copyright 2005 John Wiley & Sons, IncHistory of Information SystemsData communications over phone lines (became common and mainframes became multi-user systems)Batch processing mainframesNetworking everywherePC LANs become common195019601990200019701980Online real-time, transaction oriented systems (replaced batch processing. DBMSs become common)PC revolution12Copyright 2005 John Wiley & Sons, IncInternet MilestonesOriginally called ARPANET, the Internet began as a military-academic network1969Over 240 million servers and 400 million users20011990commercial access to the Internet beginsARPANET splits:Milnet - for militaryInternet - academic, education and research purposes only1983NSFNet created as US Internet backbone1986Government funding of the backbone ends 199413Copyright 2005 John Wiley & Sons, IncDatacom BasicsBroadband CommunicationsTelecommunicationstransmission of voice, video, data, imply longer distances- broader termData Communicationsmovement of computer information by means of electrical or optical transmission systemsconvergence14Copyright 2005 John Wiley & Sons, IncPrint ServerWeb ServerFile ServerPrinterHUBRouterClient ComputersTo other networks(e.g., Internet)Components of a Local Area NetworkServersCircuits15Copyright 2005 John Wiley & Sons, IncNetwork 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)Same as MAN except wider scale16Copyright 2005 John Wiley & Sons, IncLAN vs. BN vs. MAN vs. WAN Figure 1.2 goes here17Copyright 2005 John Wiley & Sons, IncIntranet 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 extranet18Copyright 2005 John Wiley & Sons, IncImplementation of Communications FunctionsApplicationsOSApplicationsOSMulti layer implementationBreaking down into smaller componentsEasier to implementSingle layer implemen-tation ApplicationsOSCommunicationApplicationsOSCommunication19Copyright 2005 John Wiley & Sons, IncMulti-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 70’sDeveloped to solve to the problem of internetworkingBased on 5 layersBased on Transmission Control Protocol/ Internet Protocol (TCP/IP) suite20Copyright 2005 John Wiley & Sons, Inc7-Layer Model of OSIApplication 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 Steve’s Pet AlligatorPhysical DataLink Network Transport Session Presentation Application21Copyright 2005 John Wiley & Sons, Inc7-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 network22Copyright 2005 John Wiley & Sons, IncInternet’s 5-Layer ModelApplication 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 Application23Copyright 2005 John Wiley & Sons, IncComparison of Network Models24Copyright 2005 John Wiley & Sons, IncMessage Transmission Using LayersApplicationsApplicationssenderreceiverA receiving layer wraps incoming message with an envelope Adds layer related addressing informationA receiving layer removes the layer related envelope and forwards the message up25Copyright 2005 John Wiley & Sons, IncProtocolsUsed by Network model layersSets of rules to define how to communicate at each layer and how to interface with adjacent layersreceiversenderLayer NLayer N-1Layer N+1Layer NLayer N-1Layer N+126Copyright 2005 John Wiley & Sons, IncMessage Transmission Example27Copyright 2005 John Wiley & Sons, IncImportant 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)28Copyright 2005 John Wiley & Sons, IncStandardsImportanceProvide 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 body29Copyright 2005 John Wiley & Sons, IncStandardization 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 accepted30Copyright 2005 John Wiley & Sons, IncMajor Standards BodiesISO (International Organization for Standardization) Technical recommendations for data communication interfacesComposed of each country’s 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)31Copyright 2005 John Wiley & Sons, IncMajor 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.org32Copyright 2005 John Wiley & Sons, IncSome Data Comm. StandardsLayerCommon Standards5. Application layerHTTP, HTML (Web)MPEG, H.323 (audio/video)IMAP, POP (e-mail)4. Transport layerTCP (Internet)SPX (Novell LANs)3. Network layerIP (Internet)IPX (Novell LANs)2. Data link layerEthernet (LAN)Frame Relay (WAN)PPP (dial-up via modem for MAN)1. Physical layerRS-232c cable (LAN)Category 5 twisted pair (LAN)V.92 (56 kbps modem)33Copyright 2005 John Wiley & Sons, IncEmerging Trends in NetworkingPervasive NetworkingIntegration of Voice, Video and DataNew Information Services34Copyright 2005 John Wiley & Sons, IncPervasive NetworkingMeans “Network access everywhere”Exponential 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)35Copyright 2005 John Wiley & Sons, IncRelative Capacities of Telephone, LAN, BN, WAN, and Internet Circuits.36Copyright 2005 John Wiley & Sons, IncIntegration of Voice, Video & DataAlso called “Convergence”Networks 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 video37Copyright 2005 John Wiley & Sons, IncNew 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)38Copyright 2005 John Wiley & Sons, IncImplications 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 39Copyright 2005 John Wiley & Sons, IncCopyright 2005 John Wiley & Sons, Inc. 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