optical network of SDH graduatethesiss.docx

optical network of SDH graduatethesiss.docx

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opticalnetworkofSDHgraduatethesiss

Abstract

Inrecentyears,withthedevelopmentoftheinformationsociety,theglobalInternetbusinessshowedanexplosivegrowthtrend.TheimplementationofthefiberopticalnetworkofSDHisonthebasisofthetransmissionplatformofZTEMP320,itcanprovideasimulationenvironmentfortheentireoptictransmissionnetwork.

ThispaperstudiesthetechniqueofSDHnetwork,describesthebasicprincipleofSDHmappingmultiplexing,structureofframe,categoriesoftopology,andresearchesthemethodsofprotectionoftheopticnetwork.Accordingtotheinstructionrequirement,anoptictransmissionnetworkwith9nodesissetup,theservicesbetweentwonodesareconfiguredthroughthenetworkwiththecostsorminimumresourcesofthenetwork.ThesystemtimeclockisconfiguredandchoosenodeDasprimaryclock.OfficewireiscompletedandchoosenodeDascontrollerofthenetwork.Multiplexingsectionprotectionandpathprotectionisfinished.Aftercarefuldesign,realizedsimulations,performancetestsshowthatthesynchronousdigitalhierarchynetworkisreasonable,itcanbeusedforpracticalengineering.

Keywords:

SDH;networks;opticaltransmission;STM-N;networking;multiplexing;opticalinterface

TableofContents

Chapter1Introduction1

1.1Background1

1.2CharacteristicsofSDHnetwork1

1.3Researchobjectivesandsignificance2

Chapter2SDHPrinciples4

2.1SDHsignalframestructureandmultiplexingsteps4

2.1.1SDHsignalframestructure4

2.1.2SDHmultiplexingstep6

2.2SDHequipmentlogicfunctionblocks5

2.3Thebasicnetworktopology6

2.4Self-healingnetwork8

Chapter3SDHNetworkArchitectures10

3.1Apoint-to-pointSDHlink10

3.2ASDHRingNetwork11

3.3Multi-RingSDHTopology12

3.4SDHRingProtectionMechanisms13

3.5TheRingProtectionArchitectures13

Chapter4RealizationofOpticTransmissionNetwork18

4.1Networktopology18

4.2Networkingrealization18

4.2.1Setupthenetworknodes19

4.2.2Installationoftheboardsinnodes20

4.3SystemClockconfigurations23

4.4Officewireconfigurations26

4.6Serviceconfiguration27

4.6.1AtoI2mb/s*10serviceconfiguration27

4.6.2Theresultsofservicesofnetwork30

4.7Serviceprotectionconfiguration32

4.7.1ServiceprotectionfromAtoB32

4.7.1Serviceprotectionresults35

4.8Multiplexingsectionprotection35

References39

Acknowledgements40

AppendixI41

Chapter1Introduction

Background

TheSDHisaninternationalstandardthatishighlypopularandusedforitshighspeeddatatransferofthetelecommunicationanddigitalsignals.Thissynchronoussystemhasbeenspeciallydesignedinordertoprovideasimpleandflexiblenetworkinfrastructure.Thissystemhasbroughtaconsiderableamountofchangeinthetelecommunicationnetworksthatwerebasedontheopticalfibersasfarasperformanceandcostwereconcerned.

CharacteristicsofSDHnetwork

SDHhasbeenabletorapidlydevelopandthisisitsowncharacteristicsareinseparable,anditsspecificfeaturesareasfollows:

（1）SDHtransmissionsystemsintheworldtohaveaunifiedframestructure,digitaltransmissionstandardrateandstandardopticalinterfaceisnetworkinterworkingsystem,andthereforehasgoodlateralcompatibility,itisfullycompatiblewiththeexistingPDH,andaccommodatesavarietyofnewtrafficsignals,theformationofaglobalunifiedstandarddigitaltransmissionsystemandimprovethereliabilityofthenetwork;（differentlevelsofthecodearrangement）

（2）SDHaccesssystemflowstructureofthepayloadareaoftheframeisveryregular,andthepayloadissynchronizedwiththenetwork,whichusessoftware,adirecthigh-speedsignalcandropoutofthelow-speedtributarysignalstoachievethecharacteristicsofamultiplexovercomePDHplesiochronousmultiplexedmannerforallthehigh-speedsignalmultiplexinggradualdecompositionandregenerationprocessisgreatlysimplifiedbecausetheDXC,reducingtheback-interfacemultiplexequipment,improvedtheservicedeliverynetworktransparency;

（3）Asaresultofthemoreadvancedadd-dropmultiplexer（ADM）,digitalcross-connect（DXC）,self-healingcapabilitiesandreassemblybranchnetworkbecomesstronger,withastrongsurvival.BecauseSDHframestructurearrangeda5percentoverheadbitsignal,itisparticularlypowerfulnetworkmanagementfunctions,andcanbeunifiedintoanetworkmanagementsystemforautomationnetworks,intelligent,channelutilizationandreducenetworkcostsandvascularviabilityplayedapositiverole;

（4）DuetoavarietyofSDHnetworktopology,thenetworkthatitconsistsofveryflexible,itcanenhancenetworkmonitoring,operationmanagementandauto-configurationcapabilities,optimizenetworkperformance,butalsotonetworkoperationandflexible,safeandreliable,sothenetworkisverycompleteanddiverse;

（5）SDHtransmissionandswitchingperformancehasfreecombinationoffunctionblockscomposedthroughitsfamilyofdevices,toachieveavarietyofdifferentlevelsandnetworktopologyisveryflexible;

（6）SDHdoesnotbelongtoatransmissionmediumwhichcanbeusedfortwistedpair,coaxialcable,butforthetransmissionofSDH.

Youneedtousehighdatarateopticalfiber.Thisfeatureindicates,SDHtrunkchannelssuitableforboth,butalsoforregionalchannels.Forexample,China'snationalandprovincialtrunkcablenetworkisusingSDH,anditisalsoeasytomixcompatiblewithfiber-opticcablenetwork（HFC）.

（7）SDHisstrictlysynchronizedtoensurethattheentirenetworkisstableandreliable,lesserror,andeasyadjustmentandmultiplexing.

Researchobjectivesandsignificance

Overtheyears,intelligentopticaltransmissiontechnologyhasbeenofconcernfortheindustry,ithopestobuildintelligentopticaltransmissionnetworktosolvetheproblemseveralaspectsoftheexistingtransmissionnetworkexist:

first,thetraditionalfast-growingonlinenetworkisdifficulttoadaptthedataservicewithunpredictability,dynamicallocationofnetworkbandwidth.Second,thetraditionalopticaltransmissionnetworkmainlyrelyonmanualconfigurationofnetworkconnections,time-consuminganddifficulttoadapttothemodernnetworkexpansionneedsnewbusiness.Third,inordertoimprovethereliabilityofbearerservices,thetraditionalopticaltransportnetworksneedtosetasidealargeamountofsparecapacity,reducingtheefficiencyofthetransportnetworkbandwidthusage.

Inaddition,thetraditionalwaytoprotectbusinessnetworksisrelativelysimple,thelackofadvancedprotection,restorationandroutingfunctions.SynchronousDigitalHierarchy（SDH）iswidelyusedworldwidemetrobackbonenetwork,telecommunicationnetworkandWAN.

SDHtransmissionsystemisacombinationofhigh-speedlarge-capacityopticaltransmissiontechnologyandintelligentnetworktechnology.Itprovidesconvenientandeffectivedatamultiplexinganddemultiplexingfunctions,andcanreliablytransmitdata.

Chapter2SDHPrinciples

2.1SDHsignalframestructureandmultiplexingsteps

2.1.1SDHsignalframestructure

TheSTM-N（SynchronousTransportModulelevel-1）isthefiberopticnetworktransmissionstandard.Ithasabitrateof155.52Mbit/s.Higherlevelsgoupbyafactorof4atatime:

theothercurrentlysupportedlevelsareSTM-4,STM-16,STM-64andSTM-256.Beyondthiswehavewavelength-divisionmultiplexing（WDM）commonlyusedinsubmarinecabling.

Framestructure

TheSTM-1frameisthebasictransmissionformatforSDH（SynchronousDigitalHierarchy）.ASTM-1framehasabyte-orientedstructurewith9rowsand270columnsofbytes,foratotalof2,430bytes（9rows*270columns=2430bytes）.Eachbytecorrespondstoa64kbit/schannel.

TOH:

TransportOverhead（RSOH+AU4P+MSOH）

MSOH:

MultiplexSectionOverhead

RSOH:

RegenerationSectionOverhead

AU4P:

AU-4Pointers

VC4:

VirtualContainer-4payload（POH+VC-4Data）

POH:

PathOverhead

Framecharacteristics

TheSTM-1baseframeisstructuredwiththefollowingcharacteristics:

Length:

270column×9row=2430bytes

Byte:

1-byte=64kbit/sspeechchannel

Duration（Framerepetitiontime）:

125μsi.e.8000frame/s

Rate（Framecapacity）:

2430×8×8000=155.520Mbit/s

Payload=2349bytes×8bits×8000frames/sec=150.336Mbit/s

Fig.2.1StructureofSDHframe

SDHframestructureusedtocarryablockofinformation,eachframeiscomposedoflongitudinalandtransverserows9columns270×Nbytes,eachbytecontaining8bit,theframestructureisdividedintoasectionoverhead（SectionOverhead,SOH）area,STM-Npayloadareaandsnap-pointer（AUPTR）threeregionaldistrict.

TheabovemethodcanbeobtainedwhenNisanarbitraryvaluewhentherate14,16,64,256.AscanbeseenfromFigure1,theentireframestructureisdividedintothreeregions:

thesectionoverhead（SOH）totheinformationpayloadareaandsnappointer.Sectionoverhead（SOH）istheSDHframestructureinordertoensurethenormaltransmissionofinformationandadditionalbytesfornetworkoperation,managementandmaintenanceofuse,itslocationintheSTM-Nframestructureisthefirst1~9×Ncolumnsthefirst.

ThefiguredescribesbasicSDHframeconsistingof9rowsand90columns.SDHframeiscomposedof810octets（bytes）.Transmissioniscarriedoutrowwisefromlefttorightandfromtoptobottom.Bitsaretransmittedserially.

TheSTS-1frameofSDHiscomposedofsectionoverhead,transportoverhead,payloadoverheadanddatapart.TheframestartswithfixedA1/A2bitpatternof0xf628usedforbit/octetsynchronization.SDHisreferredasoctetsynchronous.ThefirstthreecolumnsofSDHframeisreferredastransportoverhead.Thenext87columnsofthef