Ethernet_signaling

FAETrainingApril23rd,2001SanJose,CAEthernetSignalingOzdalBarkan2Overview-EthernetSignalingSamplewaveformsGig100M10MAuto-NegMDC/MDIOEthernetLineCodesNRZ,NRZI,MLT-3,ManchesterLineCodeexercise3Overview(Continued)Whatisalinecodevs.PCSCoding?Whatarethe3“codings”doneona100BASE-TXwaveform?EthernetFrameStructureStudyEthernetFrameusing10MwaveformsGigabitcodingandsignalingMDC/MDIOprotocolandwaveformsAuto-Negotiationprotocolandwaveforms41000BASE-Tand100BASE-TXWaveformsGigabit.100M.5Gigabit802.3abTestWaveforms610Mpacketdata710Base-TManchesterDifferential+2.5,-2.52010.5EthernetNomenclatureBlockEncodingLineSignalingVoltageLevelsSymbolRate/Pair(Baud)XmitPairsEfficiency(Bits/Baud)100Base-TX4B/5BMLT-3+1,0,-112510.81000Base-T4D-PAM5PAM5+1,+0.5,0,-0.5,-112542.01000Base-SX8B/10BDifferentialHigh/LowIntensity125010.81000Base-Toperationis2.0x4x125=1000Mb/sEthernetCodingandSignaling8EthernetLineCodes1101101NRZ1101101NRZI1101101MLT-31101101ManchesterNRZ-1=High,0=LowNRZI-1Changepreviouslevel,0SameaspreviouslevelMLT-3-SameasNRZI,buteveryother+1Vis-1VManchester-Eachbittimeisdividedintotwooppositehalves.Thesecondhalfmatchesbitvalue.i.e.1=secondhalfishigh,firsthalfislow.9Quiz-EthernetLineCodesNRZNRZIMLT-3ManchesterQUIZonlinecodes:Determinethebitsequenceforeachofthewaveformsabove.Notethatthefirstthreehavebittimesdefinedbythedottedlines.Manchesterencodedlinehasnobittimesdefined,it'sforyoutofigureoutwherethebittimesare.10EthernetFrameFormat1110Mpacketwaveforms&EthernetPacketFormat10MwaveformsPreambleDAandpacketdataEndofPacket10Mlinkpulses10McodingandwaveformshapingManchestercodingfordata.(seewaveshapingbelow)EndoflinecodingWaveshaping•The100nswidepulsesare“pre-equalized”.Funnyshapesecondhalfisloweramplitude.•The50nsnarrowpulsesarenotpre-equalized.1210Mbeginningofpacket1310Mpacketdata1410Mendofpacket1510Mb/sLinkPulse16100Mpacketwaveforms&coding100Mcoding(3differentkindsofcoding!!)4B/5BScramblingLinecoding100MwaveshapingRiseandfalltime3-5ns174B/5Bcoding18KeyIdeasin4B/5BcodingAllthe5Bcodesassignedtoeach4Binputdata,havebitstogglingbetween“1”and“0”GuaranteesthatPLLcanseeedgesandextractclockThereare32possiblecodewordsforeachpossible16dataword.16ofthe32codewordsareassignedtothe16possibledatainputs.Theremaining16canbeusedtodetecterrorsorforcontrol.8B/10Bencodingusedin1000BASE-X,SGMII,and10GigabitEthernet,usessimilarideas.19KeyIdeasin4B/5Bcoding(continued)Becauseofthe4B/5Bor8B/10Bcoding,thereis25%redundancyadded.Requiresthat100BASE-TXtransmits125Mb/sdataonthewire.RequiresthatMidwayPHYtransmits3.125Gb/stohandle2.5Gb/sofdata.RequiresthatSGMIIoperatesat1.25Gb/sfor1000Gb/soperation.20Quiz--4B/5BAssumingthatthescramblingisturnedoff,showhowthe100BASE-TXMLT-3waveformswilllooklikefor:IdlesDatapatternof343434…...211000BASE-Tpacketwaveforms&coding1000BASE-Tcoding(3differentkindsofcoding!!)4B/PAM5ScramblingLinecoding(PartialResponseCoding)1000MwaveshapingIEEEtemplates221000BASE-Tand100BASE-TXWaveformsGigabit.100M.231000BASE-Tsignaling-FAQQ:Ithoughtthat1000BASE-Tusedfivevoltagelevels(+1,+0.5,0,-0.5,-1V).Ilookonthescope,anditdoesn’tlookanythinglikeit?1000BASE-Tusespartialresponsecoding(seenextquestion)whichconvertsthe5levelsto17.Inaddition,1000BASE-Tisfullduplexsothatthevoltagelevelssentbythetwolinkpartnersaddup.Q:Howdoespartialresponsecodingconvertthe5levelsto17levels?Whatisitanyway?ToreduceEMIemissions,aweightedaverageisusedasfollows:Vout[n]=0.75*x[n]+0.25*x[n-1]wherex[n]andx[n-1]arethepresentandpreviousvalues.Forexampleifthepresentvaluex[n]=0.5Vandthepreviousvaluex[n-1]=-1VthenVout[n]=+0.125VIfyougothroughallthe25possiblecombinationsofx[n]andx[n-1],youwillseethat17uniqueVout[n]valuesresult.Q:Whatdoyoumeanby“forfullduplexoperationthevoltagelevelssentbythetwolinkpartnersaddup”?Ifonelinkpartnerissendingout.125Vwhiletheotherissendingout1Vshouldn’ttherebeaconflict?Ifthevoltagesourceshadzeroohmsourceimpedance,thenofcoursetherewouldhavebeenaconflict.Howeverthedrivershave100ohmdifferentialsourceimpedance.Thevoltageismeasuredonthewire,andnotonthedriversideofthesourceimpedance.IftwovoltagesourcesV1andV2eachhavesourceimpedanceofRsthenthevoltagemeasuredonthelinewillbe(V1+V2)/2.24Quiz--1000BASE-TsignalingHomeworkexerciseCreateatablewith5columnsand5rows.Therowsandcolumnsheadersshowthe5possiblevoltageassignmentsforx[n]andx[n-1].Thereare25tableentries.Usingtheformulaeforpartialresponsecoding:Vout[n]=0.75*x[n]+0.25*x[n-1]showthatthereare17uniquevaluesforeachoutput.25Auto-NegotiationAuto-NegwaveformsAuto-NegprotocolQuizLookatanyEthernetdatasheetforregister4.IdentifywhichbitareusedtoadvertisewhatcapabilitiesLookattheFLPburstnextpage.Determinewhichcapabilitiesareadvertised.26AsingleFLPburst27FLPbursts16ms+/-8ms28Auto-NegotiationPulses29FLPtiming30MDC/MDIOMDC/MDIOwaveformsMDC/MDIOprotocolLabExerciseWritetoaregisterlocationandobserveMDIO.31Questions:(a)Pleasedetermineifthisisareadorawrite?WhatisthePHYaddressshownfromthiswaveform?MDC/MDIOwaveforms32MDC/MDIOprotocol