Pair10-100Mbps100m

DirectLinkNetworks2/3/2020UIUC-CS/ECE438,Fall20062DirectLinkNetworksTwohostsconnecteddirectlyNoissuesofcontention,routing,…Keypoints:PhysicalConnectionsEncodingandModulationFramingErrorDetection2/3/2020UIUC-CS/ECE438,Fall20063InternetProtocolsPhysicalDataLinkHardware(networkadapter)Framing,errordetection,mediumaccesscontrolEncodingNetworkTransportKernelsoftwareApplicationPresentationSessionUser-levelsoftware2/3/2020UIUC-CS/ECE438,Fall20064OutlineHardwarebuildingblocksEncodingFraming2/3/2020UIUC-CS/ECE438,Fall20065HardwareBuildingBlocksNodesHosts:generalpurposecomputersSwitches:typicallyspecialpurposehardwareRouters:variedLinksCopperwirewithelectronicsignalingGlassfiberwithopticalsignalingWirelesswithelectromagnetic(radio,infrared,microwave,signaling)2/3/2020UIUC-CS/ECE438,Fall20066Links-CopperCopper-basedMediaCategory5TwistedPair10-100Mbps100mThinNetCoaxialCable10-100Mbps200mThickNetCoaxialCable10-100Mbps500mtwistedpaircoppercoreinsulationbraidedouterconductorouterinsulationcoaxialcable(coax)2/3/2020UIUC-CS/ECE438,Fall20067Links-OpticalOpticalMediaMultimodeFiber100Mbps2kmSingleModeFiber100-2400Mbps40kmglasscore(thefiber)glasscladdingplasticjacketopticalfiber2/3/2020UIUC-CS/ECE438,Fall20068Links-OpticalSinglemodeLowerattenuation(longerdistances)Lowerdispersion(higherdatarates)MultimodefiberCheaptodrive(LED’s)vs.lasersforsinglemodeEasiertoterminateO(100microns)thickcoreofmultimodefiber(samefrequency;colorsforclarity)~1wavelengththick=~1microncoreofsinglemodefiber2/3/2020UIUC-CS/ECE438,Fall20069Links-OpticalAdvantagesofopticalcommunicationHigherbandwidthsSuperiorattenuationpropertiesImmunefromelectromagneticinterferenceNocrosstalkbetweenfibersThin,lightweight,andcheap(thefiber,nottheoptical-electricalinterfaces)2/3/2020UIUC-CS/ECE438,Fall200610LeasedLinesPOTS64KbpsISDN128KbpsADSL1.5-8Mbps/16-640KbpsCableModem0.5-2MbpsDS1/T11.544MbpsDS3/T344.736MbpsSTS-151.840MbpsSTS-3155.250Mbps(ATM)STS-12622.080Mbps(ATM)2/3/2020UIUC-CS/ECE438,Fall200611WirelessCellularAMPS13Kbps3kmPCS,GSM300Kbps3km3G2-3Mbps3kmWirelessLocalAreaNetworks(WLAN)Infrared4Mbps10m900Mhz2Mbps150m2.4GHz2Mbps150m2.4GHz11Mbps80mBluetooth700Kbps10mSatellitesGeosynchronoussatellite600-1000MbpscontinentLowEarthorbit(LEO)~400Mbpsworld2/3/2020UIUC-CS/ECE438,Fall200612EncodingProblemswithsignaltransmissionAttenuation:SignalpowerabsorbedbymediumDispersion:AdiscretesignalspreadsinspaceNoise:Randombackground“signals”digitaldata(astringofsymbols)digitaldata(astringofsymbols)modulatordemodulatorastringofsignalsmodulatordemodulator2/3/2020UIUC-CS/ECE438,Fall200613EncodingGoal:UnderstandhowtoconnectnodesinsuchawaythatbitscanbetransmittedfromonenodetoanotherIdea:ThephysicalmediumisusedtopropagatesignalsModulateelectromagneticwavesVaryvoltage,frequency,wavelengthDataisencodedinthesignal2/3/2020UIUC-CS/ECE438,Fall200614Analogvs.DigitalTransmissionAdvantagesofdigitaltransmissionoveranalogReasonablylow-errorratesoverarbitrarydistancesCalculate/measureeffectsoftransmissionproblemsPeriodicallyinterpretandregeneratesignalSimplerformultiplexingdistinctdatatypes(audio,video,e-mail,etc.)Twoexamplesbasedonmodulator-demodulators(modems)ElectronicIndustriesAssociation(EIA)standard:RS-232(-C)InternationalTelecommunicationsUnion(ITU)V.329600bpsmodemstandard2/3/2020UIUC-CS/ECE438,Fall200615RS-232CommunicationbetweencomputerandmodemUsestwovoltagelevels(+15V,-15V),abinaryvoltageencodingDataratelimitedto19.2kbps(RS-232-C);raisedinlaterstandardsCharacteristicsSerial:onesignalingwire,onebitatatimeAsynchronous:linecanbeidle,clockgeneratedfromdataCharacter-based:senddatain7-or8-bitcharacters2/3/2020UIUC-CS/ECE438,Fall200616RS-232TimingDiagramidlestart1110000stopidle-15++15TimeVoltage2/3/2020UIUC-CS/ECE438,Fall200617RS-232OnebitperclockVoltageneverreturnsto0V0Visadead/disconnectedline-15Visbothidleand“1”initiatessendbypushingto15Vforoneclock(startbit)MinimumdelaybetweencharactertransmissionsIdleforoneclockat-15V(stopbit)Onecharacterleadsto2+voltagetransitionsTotalof9bitsfor7bitsofdata(78%efficient)Startandstopbitsalsoprovideframing2/3/2020UIUC-CS/ECE438,Fall200618VoltageEncodingCommonbinaryvoltageencodingsNon-returntozero(NRZ)NRZinverted(NRZI)Manchester(usedbyIEEE802.3—10MbpsEthernet)4B/5B2/3/2020UIUC-CS/ECE438,Fall200619Non-ReturntoZero(NRZ)SignaltoDataHigh1Low0CommentsTransitionsmaintainclocksynchronizationLongstringsof0sconfusedwithnosignalLongstringsof1scausesbaselinewanderBothinhibitclockrecoveryBits0010111101000010NRZ2/3/2020UIUC-CS/ECE438,Fall200620Non-ReturntoZeroInverted(NRZI)SignaltoDataTransition1Maintain0Bits0010111101000010NRZNRZICommentsStringsof0’sstillaproblem2/3/2020UIUC-CS/ECE438,Fall200621ManchesterEncodingSignaltoDataXORNRZdatawithclockHightolowtransition1Lowtohightransition0CommentsSolvesclockrecoveryproblemOnly50%efficient(1/2bitpertransition)Bits0010111101000010NRZClockManchester2/3/2020UIUC-CS/ECE438,Fall2006224B/5BSignaltoDataEncodeevery4con