Data And Computer Communications - Philadelphia

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16-Jul-17Data and ComputerCommunicationsCHAPTER 1Tenth Editionby William StallingsData Communications, Data Networks,and the InternetData and Computer Communications, TenthEdition by William Stallings, (c) PearsonEducation - Prentice Hall, 2013“The fundamental problem ofcommunication is that of reproducing atone point either exactly or approximately amessage selected at another point”Data Communications, DataNetworks, and the Internet - The Mathematical Theory ofCommunication,Claude Shannon Data and Computer Communications, Ninth Edition byWilliam Stallings, (c) Pearson Education - Prentice Hall,2011Data Communications and Networking for Today’s EnterpriseTrendsData Transmission and Network Capacity RequirementsConvergenceA Communications ModelData Communications A Data Communications Model The Transmission of InformationNetworks Wide Area Networks Local Area Networks Wireless NetworksThe Internet Origins of the Internet Key Elements Internet Architecture1

16-Jul-17Technological AdvancementDriving ForcesNotable TrendsTrend toward faster andcheaper, in both computing andcommunication More powerful computers supportingmore demanding applications The increasing use of optical fiber andhigh-speed wireless has broughttransmission prices down and greatlyincreased capacityThe Internet, the Web, andassociated applications haveemerged as dominant featuresfor both business and personalnetwork landscapes “Everything over IP” Intranets and extranets are being used toisolate proprietary informationToday’s networks are more“intelligent” Differing levels of quality of service(QoS) Variety of customizable services in theareas of network management andsecurityMobility iPhone, Droid, and iPad have becomedrivers of the evolution of businessnetworks and their use Enterprise applications are now routinelydelivered on mobile devices Cloud computing is being embracedData and Computer Communications, Ninth Edition byWilliam Stallings, (c) Pearson Education - Prentice Hall,20112

16-Jul-17Changes in NetworkingTechnologyEmergence of High-Speed LANs * Emergence of high-speed LANsTwosignificanttrends alteredtherequirementsof the LAN* Corporate WAN needs* Digital electronicsPersonal computers and microcomputerworkstations have become an essential tool foroffice workersExplosive growth Corporate Wide AreaNetworking NeedsGrowing use of telecommutingNature of the application structure has changedIntranet computingMore reliance on personal computers, workstations, and serversMore data-intensive applicationsMost organizations require access to the InternetTraffic patterns have become more unpredictableAverage traffic load has risenLANs have beenrecognized as aviable andessentialcomputingplatformExamples of requirements that call for higherspeed LANs: creationof highspeedWANsof speed andcomputing powerof personalcomputersCentralized server farmsPower workgroupsHigh-speed local backboneDigital Electronics The rapid conversion of consumer electronicsto digital technology is having an impact onboth the Internet and corporate intranets Image and video traffic carried by networks isdramatically increasing Because of their huge storage capacity digital versatiledisks (DVDs) are being incorporated into Web sites Digital camcorders have made it easier to make digitalvideo files to be placed on corporate and Internet WebsitesMore data is transported off premises and into the wide areaData and Computer Communications, Ninth Edition byWilliam Stallings, (c) Pearson Education - Prentice Hall,20113

16-Jul-17Convergence The merger of previouslydistinct telephony andinformation technologies andmarkets Involves: Moving voice into adata infrastructure Integrating all the voiceand data networksinside a userorganization into asingle data networkinfrastructure Then extending thatinto the wireless arena Layers:ApplicationsThese are seenby the end usersEnterprise servicesServices theinformationnetwork suppliesto s available tothe enterpriseFoundation is packetbased transmissionusing the InternetProtocol (IP)Increases the functionand scope of both theinfrastructure and theapplication baseTable 1.1Communications TasksData and Computer Communications, Ninth Edition byWilliam Stallings, (c) Pearson Education - Prentice Hall,20114

16-Jul-17Transmission LinesTransmission MediumsCapacityThe basic building block ofany communications facilityis the transmission lineThe business manager isconcerned with a facilityproviding the requiredcapacity, with acceptablereliability, at minimum costTwo mediums currently drivingthe evolution of data communicationstransmission are:ReliabilityFiber optic transmissionsCostandTransmissionLineWireless transmissionsNetworksTransmission Services Remain the most costly component of acommunications budgetTwo major approaches to greater efficiency: By2016 there is over 20 billion fixed andmobile networked devices This affects traffic volume in a number ofways: It enables a user to be continuously consumingnetwork capacity Capacity can be consumed on multiple devicessimultaneously Different broadband devices enable differentapplications which may have greater trafficgeneration capabilityData and Computer Communications, Ninth Edition byWilliam Stallings, (c) Pearson Education - Prentice Hall,20115

16-Jul-17NetworkingAdvances in technology have led to greatlyincreased capacity and the concept ofintegration, allowing equipment andnetworks to work simultaneouslyWide Area Networks (WANs) Span Require RelyVoiceDataImageVideoa large geographical areathe crossing of public right-of-waysin part on common carrier circuits Typicallyconsist of a number ofinterconnected switching nodesCircuit Switching UsesWide Area NetworksAlternative technologies used include: Circuit switchingPacket switchingFrame relayAsynchronous Transfer Mode (ATM)Data and Computer Communications, Ninth Edition byWilliam Stallings, (c) Pearson Education - Prentice Hall,2011a dedicated communications path Connected sequence of physical linksbetween nodes Logical channel dedicated on each link Rapid transmission The most common example of circuitswitching is the telephone network6

16-Jul-17Packet Switching Dataare sent out in a sequence of smallchunks called packets Packets are passed from node to nodealong a path leading from source todestination Packet-switching networks are commonlyused for terminal-to-terminal computer andcomputer-to-computer communicationsAsynchronous Transfer Mode(ATM)Frame Relay Developedto take advantage of high datarates and low error rates Operates at data rates of up to 2 Mbps Key to achieving high data rates is to stripout most of the overhead involved witherror controlLocal Area Networks (LAN) Referredto as cell relay Culmination of developments in circuitswitching and packet switching Uses fixed-length packets called cells Works in range of 10s and 100s of Mbpsand in the Gbps range Allows multiple channels with the data rateon each channel dynamically set ondemandData and Computer Communications, Ninth Edition byWilliam Stallings, (c) Pearson Education - Prentice Hall,20117

16-Jul-17The Internet Internetevolved from ARPANET Developed to solve the dilemma ofcommunicating across arbitrary, multiple,packet-switched networks Foundation is the TCP/IP protocol suiteTable 1.2Internet Terminology Central Office (CO) Telecommunications equipmentthat is located on the customer’spremisesInternet Service Provider (ISP) A company that provides othercompanies or individuals withaccess to, or presence on, theInternetNetwork Access Point (NAP) Customer PremisesEquipment (CPE) The place where telephonecompanies terminate customerlines and locate switchingequipment to interconnect thoselines with other networksNetwork Service Provider(NSP) One of several major Internetinterconnection points thatserve to tie all the ISPs togetherA company that providesbackbone services to anInternet service provider (ISP)Point of Presence (POP) A site that has a collection oftelecommunications equipment,usually refers to ISP ortelephone company sites(Table can be found on page 27 in textbook)Data and Computer Communications, Ninth Edition byWilliam Stallings, (c) Pearson Education - Prentice Hall,20118

16-Jul-17Summary Transmission mediums Internet Data and Computer Communications, Ninth Edition byWilliam Stallings, (c) Pearson Education - Prentice Hall,2011Wide Area NetworksLocal Area NetworksWireless NetworksOriginKey elementsInternet architectureTrends challengingdata communications: Network categories: Fiber opticWireless Traffic growthDevelopment of newservicesAdvances intechnologyData Transmissionand Network CapacityRequirementsConvergence9

Data and Computer Communications, Ninth Edition by William Stallings, (c) Pearson Education - Prentice Hall, 2011 4 Convergence The merger of previously distinct telephony and information technologies and markets Enterprise servicesInvolves: Moving voice into a data infrastructure Integrating all the voice and data networks inside a user