Introduction to MIS - Chapter 3: Networks and Telecommunications

Introduction to MISChapter 3Networks and TelecommunicationsNetworksTeamworkCommunicationSchedulingSharingInternetSuppliersCustomersBanksInternalExternalOutlineIntroductionSharing DataSharing HardwareSharing SoftwareComponents of a NetworkComputersMediaConnection DevicesSoftwareNetwork StructureShared MediaSwitchedStandardsThe InternetHow the Internet WorksInternet 2Mobile CommerceGlobal TelecommunicationsTechnical ProblemsPolitical ComplicationsCultural IssuesCommentCases: Specialty RetailAppendix: Creating Web PagesSharing Data: TransactionsDatabase ManagementSystem and Web ServerInternetTeam DocumentFile Server and DatabaseData and ToolsReport andCommentsSharing Data: Decisions & SearchesDecisions & searchesTeamwork & joint authorshipSharing Data: E-mailInternet1. User creates e-mail message.2. Message transferred to account on server.3. Transferred via the Internet to the destination account.4. Message received when user checks e-mail.Sharing Data: Calendars 8:00 Mgt meeting 8:30 (open) 9:00 Staff meeting 9:30 Staff meeting10:00 new meetingHardware SharingPrintersStorageProcessorsFiles are transferred from workstations to the server.Software automatically copies files to tapes.LAN administrator can restore files if needed.Corporate orexternal computeraccessServerShared PrinterWorkstationstape drive(backup)VoiceComputerSent as packets: 1 2 3 4 5Sent as packets: A B C D EChicagoNew YorkDallasAtlantaE4CB2A15D3Packet-Switched NetworksData, Voice, VideoAll converted to packetsPacket has data, destination, and source addressSwitched servicesPackets routed as neededReassembled at destinationNetwork ComponentsComputersServersWork stationsMediaCablesFiber opticRadioInfraredConnection devicesLAN cardLAN cardLAN cardLAN cardShared PrinterServerPersonal ComputerPersonal ComputerRouter or SwitchInternetFirewallServer ScalabilitySun 10000Sun 3800Sun Ultra 5CompaqIncreasing performance within a product family.Server farms distribute the workload. Add more computers for more power.Rack mount server farm.Network Transmission MediaElectricityFiber opticsRadio wavesCoaxialExample:Cable TVShieldRadio or Micro WavesExample:Cellular phonesglass or plasticFiber Optic CableExample:Long distance phone linesantennaTwisted PairExample:Local phone linesreflective claddingFiber OpticsFasterMore dataLess magnetic interferenceLong stretches without repeaters900 copper wires can be replaced by one fiber optic line (for telephone connections).Frequency SpectrumAll waves behave similarlySoundRadioMicroLightFrequency differencesAmount of dataDistanceInterference / NoiseELFVLFLFMFHFVHFUHFMicrowaveOptical1001K100K1M10M100M1G10GHertzNavy/submarinesTV: 220M - 500 MHzAM: 550K - 1650 KHzPublic Safety: 150M - 160 MHzPublic Safety: 460M - 500 MHzCellular phones: 800 MHzCordless phones (some): 900 MHzPers. Com. Sys (PCS): 1.85 G - 2.2 GHz PCS ET: 2 GHzTV: 54M - 216 MHzFM: 88M - 108 MHz CapacityA thin fiber optic cable can carry as much data as 900 single copper wires, with minimal interference, and superior tensile strength.The Importance of BandwidthShared ConnectionsWith shared connections, machines have to take turns, and congestion can slow down all connections.With switched connections, each computer has the full bandwidth of the connection at all times. Performance depends on how fast the switch can handle connections.Time DivisionABDCtimeACACAComputers A and B split their messages into packets and sharethe transmission medium by taking turns sending the data.Frequency DivisionABDCfrequency3500 HzACComputers A and B split the frequency: A uses a higher spectrum.By listening only to the assigned frequency, multiple transmissionscan occur at the same time.Spread SpectrumABDCfrequencytimeSharing a medium by both frequency and time is one methodof spread spectrum transmission. It is efficient for many computersbecause the full bandwidth can be utilized over time and frequency.WirelessCommunicationMicrowave transmissions are used to provide communications for cellular phones and laptop computers. As prices of phones, portable computers, and communication costs decrease, increasing numbers of workers are choosing wireless technologies.Connecting NetworksThe need for standardsA changing environmentBackbone fiber opticHubSwitchHubRadio-based networkInternetRouters or SwitchesShared-Media NetworkShared MediaTapSwitched NetworkSwitchServersWorkstations/PCsBuilding 1Building 2Enterprise NetworkSwitchServersWorkstations/PCsFiber opticInternet – ISPFirewallSubsidiaryClient/Server NetworkClient serverPeer-to-peerOperating systemMultitaskingServerServerClientsClientsWorkgroup PrinterWorkgroup PrinterTCP/IP Reference ModelMessageHeader 3Trailer 3MessageHeader 3Trailer 3MessageHeader 3Trailer 3MessageHeader 2Trailer 2Header 3Trailer 3MessageHeader 3Trailer 3MessageHeader 2Trailer 2Header 1Trailer 14. Application3. Transport (TCP)2. Internet (IP)1. PhysicalTCP/IP ReferenceApplicationMail, Web, FTPAuthentication, compression, user servicesTransportPacketize data and handle lost packetsEstablish connections through numbered portsInternet Protocol (IP)Route packets to destinationRequires unique host addresses: IPv4=32-bit; IPv6=128-bitRequires standards and cooperationSubnetPhysical connectionsTransfers bits with some form of error correctionISO-OSI Reference ModelApplicationPresentationSessionTransportNetworkData LinkPhysicalLayer 7Layer 6Layer 5Layer 4Layer 3Layer 2Layer 1ApplicationPresentationSessionTransportNetworkData LinkPhysicalPhysical MediaOriginal DataTranslateSign on and resourcesData PacketRAdd routing dataRACAddresses &Error CheckRACRACThe InternetIntroduction to the InternetNo controlServicesMailTelnetFTPWWWWEB searchingAltaVistaHotBotLycosWebCrawlerYahooHow the Internet WorksIndividualInternetserviceprovider (ISP)PhonecompanyNetworkserviceprovider (NSP)BackbonenetworkPhonecompanyCompanyWeb siteDial-up: 33.3 - 56 KbpsISDN: 128 KbpsDSL: 256 Kbps - 6 MbpsCable: 1 to 10 MbpsCablecompanyT1: 1.544 MbpsT3: 44.736 MbpsOC3: 155.52 MbpsOC12: 622 MbpsInternet ConnectionsBackbone providersAT&TGTEWorldcom/MCISprintQwestNetwork service providers1998: 39AGISAT&TCable & WirelessIBMMCI/WorldcomQwestSprintUUNetPhone companiesRegional Bell operating companies (RBOCs) (6)Competitive local exchange carriers (CLECs) (new)Cable companiesAT&TCablevisionRegional.SatelliteDirect SatelliteStarbandInternet service providersAmerica OnlineMicrosoft NetworkEarthlinkM-CommerceInternet access everywhereCell phonesPDAsLaptopsGreat potentialLimited usabilityBetter than voice?Cell Phones and Wireless CommunicationWireless cells work by handing off the wireless connection to the next tower as the caller moves.Connections to multiple towers at one time enables the system to triangulate to get a fairly precise location of the cellular device--even when it is not in a call.Location knowledge will make it possible (although perhaps not desirable) to offer new business opportunities as people move into range.Global TelecommunicationsTechnical problemsMultiple standardsLanguageDeveloping nationsTime zonesLimits to space & wavesPolitical complicationsTransborder data flowsTaxesPrivacyAccessibilityCultural issuesWhat is an object?Management & controlCases: Specialty RetailCases: Ben & Jerry’sAppendix: Creating Web PagesDetermine the content.Define a style.Create each page.TextGraphicsLink the pages.Test your work.Transfer pages to a Web site.Appendix: Style Sheets BODY { margin-left: 5px; font: 10pt "Times New Roman", Times, serif; color: black; text-align: left; background-color: #e0ffff; } P { margin-left: 0px; font: 10pt "Times New Roman", Times, serif; color: black; background: transparent; } H1 { margin-left: 0px; font: 16pt "Times New Roman", Times, serif; color: black; font-weight: bold; background: transparent; }Page 3Page 2Page1Style SheetBody { }P {}Appendix: Sample HTMLSample HTML PageSection OneThis is a sample paragraph on a sample page.Appendix: Publishing FilesYour computerWeb serverInternet or intranetInitialpagesAccessibleWebpagesTransfer methods: Microsoft Front Page extensions FTP: file transfer protocolWeb Development HintsStart with a tool like Microsoft Word (or Front Page, etc.).Get a good graphics packageKeep page size small30,000 - 50,000 bytes typically takes 8 - 15 secondsFirst develop the pages on your own computer.Test all links.Transfer later.Use style sheets.Consistency.Ease of change.Study design elements and art.Formal training/art classes.Study other sites.Watch for and create trends.