已阅读5页,还剩5页未读, 继续免费阅读
版权说明:本文档由用户提供并上传,收益归属内容提供方,若内容存在侵权,请进行举报或认领
文档简介
173CHAPTER8TRAFCMANAGEMENTANDCONTROL81INTRODUCTIONCOMMUNICATIONSTRAFCMANAGEMENTANDCONTROLISINMANYWAYSSIMILARTOMANAGINGANDCONTROLLINGVEHICULARTRAFCINALARGECITYTHINKOFTHEMAINAVENUESASARTERIALTRAFCBEARINGLINKSTHATBRINGTRAFCVEHICLESANDPEDESTRIANSTOINTERSECTIONSWITHTRAFCLIGHTSINTHISCASE,TRAFCLIGHTSMAYBECONSIDEREDTHEEQUIVALENTOFTRAFCSWITCHINGNODES,WHEREASVEHICLESANDPEDESTRIANSARETHEEQUIVALENTOFPACKETSOFINFORMATIONINCOMMUNICATIONSIFTRAFCLIGHTSAREWELLSYNCHRONIZEDANDTHEYTURNGREENANDREDFORTHECORRECTAMOUNTOFTIMEACCORDINGTOVOLUMEOFVEHICLESORPEDESTRIANSATTHEQUEUES,THENTRAFCFRUSTRATINGJAMSAREELIMINATEDORATLEASTMINIMIZEDBUTHOWDOWECONTROLALLLIGHTSTOACCOMPLISHTHISCURRENTLY,INLARGECITIES,INTELLIGENTCAMERASMONITORTHEOWOFCARSANDTHEQUEUESATTHEINTERSECTIONS,ANDBASEDONATRAFCALGORITHM,LIGHTSCONTROLTHEOWTOMINIMIZEATLEASTINTHEORYCONGESTIONHOWEVER,CURRENTLYTHISREQUIRESHUMANINTERVENTION,ANDITISNOTCOMPLETELYAUTOMATICINFACT,THESCENARIOOFCOMPUTERCONTROLLINGTRAFCLIGHTSHASINSPIREDAHOLLYWOODMOVIETHISCITYTRAFCPARADIGM,ASCOMPLEXASITMAYSEEM,ISMUCHSIMPLERTHANACOMMUNICATIONSSWITCHINGNODE,WHERETHEREAREMANYINPUTANDOUTPUTBERS,EACHBERHASMANYOPTICALCHANNELS,ANDEACHOPTICALCHANNELCARRIESASIGNALEG,OC48,WHICHISTHEMULTIPLEXOFMANYTRIBUTARIESINTHISSCENARIO,SOMESIGNALSMAYNEEDTOBESWITCHEDINTACT,WHEREASSOMEOTHERSNEEDTOBEDEMULTIPLEXEDSINCEDIFFERENTTRIBUTARIESNEEDTOBESWITCHEDTODIFFERENTOUTPUTPORTSMOREOVER,THESIGNALMAYCONTAINSYNCHRONOUSPAYLOADSVOICE,VIDEOANDASYNCHRONOUSIP,ETHERNET,ANDOTHERDATASPECICTHATIS,THEREAREDIFFERENTPROTOCOLSTOBEEXECUTEDANDDIFFERENTREQUIREMENTSSEEFIGS419AND426THUS,SOMEPAYLOADSNEEDTOBESWITCHEDWITHOUTDELAY,WHEREASSOMEOTHERSMAYBETEMPORARILYBUFFEREDWITHSUCHCOMPLEXITY,THECITYTRAFCCONTROLPROBLEMSUDDENLYSEEMSVERYSIMPLECOMPAREDWITHTHECOMMUNICATIONSTRAFCCONTROLBASEDONTHISCOMMUNICATIONSPARADIGM,INDWDMOPTICALNETWORKS,THEREARETWOMAJORMANAGEMENTTYPESONEISCONCERNEDWITHTHEWAVELENGTHMANAGEMENTACROSSTHENETWORKANDTHEOTHERWITHCLIENTBANDWIDTHMANAGEMENTINTHEFOLLOWING,WEASSUMETHATCONTROLMESSAGESTHATAREREQUIREDFORBANDWIDTHMANAGEMENTANDCONNECTIVITYESTABLISHMENTAREACCOMPLISHEDUSINGSPECICMESSAGESANDALGORITHMSBASEDONONEOFTHESEVERALWELLKNOWNMETHODSDISTRIBUTEDORCENTRALIZEDCONTROLANDINCHANNELOROUTOFCHANNELMESSAGESCENTRALIZEDCONTROLIMPLIESTHATALLNODESSENDCONGURATIONANDSTATEMESSAGESTOACENTRALIZEDSYSTEMTHATOVERSEESTHEOPERATIONANDCONNECTIVITYESTABLISHMENTACROSSTHEOVERALLNETWORK,FIG81ALTHOUGHCENTRALIZEDCONTROLISEFCIENT,ANAGREEMENTMUSTEXISTAMONGALLNETWORKOPERATORSIFDIFFERENTONCOMMONNETWORKPARAMETERS,PERFORMANCEOBJECTIVES,ANDPROTOCOLLANGUAGESDISTRIBUTEDCONTROLIMPLIESTHATALLNODESINTHEOVERALLNETWORKPARTAKEINTHENETWORKCONTROL,FIG82THISISACCOMPLISHEDWITHEXTENSIVEPROTOCOLSTONDTHEBESTROUTEINTHENETWORKASWELLSVKARTALOPOULOS,NEXTGENERATIONINTELLIGENTOPTICALNETWORKS,CSPRINGER20081748TRAFCMANAGEMENTANDCONTROLNMSEMS/NMSSTANDARDINTERFACEEMSAEMSBEMSNVENDORSPECIFICORSTANDARDINTERFACENENENENENENENENENEMULTIVENDORNETWORKFIG81CENTRALIZEDCONTROLOFAMULTIVENDORNETWORKENVIRONMENTCONSISTSOFINTERCONNECTEDNETWORKELEMENTSNETHATCOMPRISENETWORKDOMAINS,ANDEACHDOMAINISCONNECTEDWITHTHENETWORKMANAGEMENTSYSTEMNMSVIAELEMENTMANAGEMENTSYSTEMSEMSASTOMANAGETHEHEALTHOFTHENETWORKANDTRAFCEFCIENCYFOREXAMPLE,THEHOPBYHOPROUTEDISCOVERYANDOODINGTHENETWORKARETWOWELLKNOWNALGORITHMS1BECAUSEDISTRIBUTEDCONTROLUSESEXTENSIVEPROTOCOLSANDALGORITHMS,ANAGREEMENTMUSTEXISTAMONGALLNETWORKOPERATORSIFDIFFERENTONCOMMONNETWORKINTERFACEPROTOCOLSANDPERFORMANCEOBJECTIVESINCHANNELMESSAGESAREMESSAGESEMBEDDEDINTHEOVERHEADOFTHESAMECHANNELORPACKETTHATTRANSPORTSCLIENTDATAFOREXAMPLE,INSONET/SDH,SPECICCONTROLMESSAGESFORERRORCONTROLANDPROTECTIONTOSWITCHINGAREINCLUDEDINTHEOVERHEADCONVERSELY,OUTOFCHANNELMESSAGESAREMESSAGESTHATUSESPECICALLYALLOCATEDCHANNELSORPACKETSFOREXAMPLE,THISISTHECASEINATMWHICHUSESSPECICATMCELLSFORCALLADMISSIONCONTROLANDSERVICELEVELAGREEMENTNEGOTIATION,ANDINTHEOTNCASE,ITUSESASEPARATESUPERVISORYCHANNEL,FIG83NETWORKNCISUBNETWORKDOMAINONNINCIONNIOPTNETTONETINTERFACENCINETWORKTOCLIENTINTERFACEFIG82INDISTRIBUTEDCONTROL,ALLNODESPARTAKEINTHEDISCOVERYOFTHEBESTOPTICALROUTEACROSSTHEOVERALLNETWORK,WHICHMAYCONSISTOFSUBNETWORKSORDOMAINS83WAVELENGTHMANAGEMENTFIG83INOTN,OVERHEADINFORMATIONABOUTSECTION,PATH,ANDTANDEMCONNECTIONISTRANSPORTEDWITHANOUTOF175OCHSECTIONOCHTCOPTICALSUPERVISORYCHANNELOSCOCHPATHOCHPAYLOADTRANSPORTEDOVEROTMNTCTANDEMCONNECTIONOCHOVERHEADTRANSPORTEDOVEROSC82CLIENTBANDWIDTHMANAGEMENTCLIENTBANDWIDTHMANAGEMENTISAFUNCTIONTHATISREQUIREDBYALLTYPESOFCOMMUNICATIONSYSTEMSANDNETWORKS,VOICEORDATA,SMALLORLARGETHISFUNCTIONMUSTASSURETHATCLIENTSDATAISDELIVEREDRELIABLY,SECURELY,TIMELY,ANDWITHTHEAGREEDQUALITYOFSERVICE2,REGARDLESSOFTHEMETHODITISTRANSPORTED,NAMELY,BYMEANSOFTRIBUTARYORCONTAINERUNITSASINSYNCHRONOUSTRAFC,ORDIRECTLYMAPPEDORBULKLLEDINTHESYNCHRONOUSPAYLOADSEEFIG210,ORPACKETIZEDANDTRANSPORTEDBYMEANSOFADAPTATIONCLIENTBANDWIDTHMANAGEMENTHASTWOOBJECTIVES1DELIVERTHECLIENTSBANDWIDTHACCORDINGTOSERVICELEVELAGREEMENTANDQUALITYOFSERVICEAND2INCREASETHENETWORKBANDWIDTHEFCIENCYBYLLINGTHEPAYLOADENVELOPEORTHENETWORKBANDWIDTHCAPACITYWITHTHECLIENTDATAASMUCHASPOSSIBLEHOWEVER,ASTRAFCBECOMESMOREELASTIC3,ASTHEAGGREGATEBANDWIDTHDEMANDINCREASES,ASFAULTSANDSEVEREDEGRADATIONSOCCURINNODES,ONBERLINKS,ANDINOPTICALCHANNELS4,TRAFCMANAGEMENTBECOMESMORECHALLENGING83WAVELENGTHMANAGEMENTINMODERNDWDMSYSTEMS,EACHWAVELENGTHOFTHEITUTGRIDISUSEDASASEPARATEOPTICALPATH,ALSOCALLEDALIGHTPATH,WHICHLIKEAHIGHWAYCARRIESMANYCLIENTSIGNALSESTABLISHINGENDTOENDCONNECTIVITYCURRENTLY,THEREARETWOFUNDAMENTALLYDIFFERENTMETHODSFORESTABLISHINGLIGHTWAVECONNECTIVITYTHERSTMETHODCONSIDERSAPATHFORWHICHTHESAMEWAVELENGTHOVERTHEENTIREENDTOENDPATHISASSIGNEDEVENIFTHELIGHTPATHISACROSSSEVERALSUBNETWORKS,EACHMANAGEDBYDIFFERENTNETWORKOPERATORTHISCASEISKNOWNASSINGLEWAVELENGTHPATHCONNECTIVITY,FIG84ALTHOUGHATRSTGLANCETHISMETHODMAYSEEMSIMPLISTIC,INAMULTINODENETWORK,ITISCOMPLEX,ANDITMAYRESULTINWAVELENGTHCONTENTIONORBLOCKINGANDTHUSNETWORKINEFCIENCYTHESECONDMETHODCONSIDERSDIFFERENTWAVELENGTHSTHATARECONCATENATEDOVERACOMPLETEPATHTHISMETHODISNETWORKB2B1SUBNETWORKFIG84AMESHNETWORKMAYESTABLISHCONNECTIVITYDOMAINUSINGTHESAMEWAVELENGTHENDTOENDORMULTIPLECONCATENATEDWAVELENGTHSA1A21768TRAFCMANAGEMENTANDCONTROLKNOWNASMULTIWAVELENGTHPATHCONNECTIVITYTHELATTERMETHODREQUIRESEITHERWAVELENGTHCONVERTERSATEACHNODEORNODESTHATAREOPTICALELECTRICALOPTICALOEOTHISMETHODHASTHEADDEDADVANTAGEOFUTILIZINGDIFFERENTWAVELENGTHSOFTHEITUTGRIDONTHELINKSTHATMAKEUPTHEPATHANDTHUSITINCREASESWAVELENGTHUTILIZATIONANDEFCIENCYHOWEVER,THISMETHODADDSTONODEDESIGNCOMPLEXITYANDCOSTOFCOMPONENTSSUBSTANTIALLY,ANDTHUSTOFAILUREMODES,PROVISIONING,ANDMAINTENANCEWAVELENGTHMANAGEMENTFORTHESINGLEWAVELENGTHPATHCONNECTIVITYMETHODISSIMPLERALTHOUGHLIMITEDANDBANDWIDTHINEFCIENTTHEREASONISTHATTHENETWORKMAYBEUNABLETONDTHESAMEWAVELENGTHFROMSOURCETODESTINATIONFORALLPOSSIBLEROUTESLEADINGTOPOTENTIALWAVELENGTHBLOCKINGFOREXAMPLE,IFWECONSIDERAMESHDWDMNETWORK,THEBLOCKINGPROBABILITYISAFUNCTIONOFTOPOLOGY,NUMBEROFBERSPERNODEANDNUMBEROFWAVELENGTHSOPTICALCHANNELSPERBER,ANDALSONUMBEROFDROPPEDANDADDEDCHANNELSATEACHNODEWEASSUMETHATNODESINAMESHNETWORKAREALSOOPTICALADDDROPMULTIPLEXINGNODESOADMTHUS,ASTHENUMBEROFBERSPERNODEANDWAVELENGTHSPERBERINCREASE,THEPROBABILITYFORBLOCKINGDECREASESTHEKEYOBJECTIVEINTHISCASEISBANDWIDTHEFCIENCY5WAVELENGTHMANAGEMENTFORTHEMULTIWAVELENGTHPATHCONNECTIVITYMETHODISMORECOMPLEXALTHOUGHMOREBANDWIDTHEFCIENTANDBECAUSEOFTHEADDEDHARDWARECOMPLEXITYADDEDWAVELENGTHCONVERTERS,ITISCOSTLIERINTHISCASE,IFWECONSIDERAMESHDWDMNETWORKWITHWAVELENGTHCONVERTERSINEACHNODE,THEBLOCKINGPROBABILITYISAFUNCTIONOFTOPOLOGY,NUMBEROFBERSPERNODEANDNUMBEROFWAVELENGTHSOPTICALCHANNELSPERBER,NUMBEROFDROPPEDANDADDEDCHANNELSATEACHNODE,ANDALSONUMBEROFCONVERTERSINEACHNODETHUS,ASTHENUMBEROFBERSPERNODEANDWAVELENGTHSPERBERINCREASES,THEREQUIREDNUMBEROFCONVERTERSINEACHNODEINCREASES,THEPROBABILITYFORBLOCKINGISALMOSTELIMINATEDALTHOUGHTHECOSTOFTHENETWORKANDWAVELENGTHMANAGEMENTINCREASESDRAMATICALLYASARESULT,THEOBJECTIVEINTHISCASEISTOBALANCEBANDWIDTHEFCIENCYANDOPTIMIZECOSTAHYBRIDMETHODMAYBEUSEDTOACCOMPLISHTHISALLOCATEANUMBEROFWAVELENGTHSTHATPROVIDESINGLEWAVELENGTHCONNECTIVITYOVERSELECTEDPATHSANDALLOCATETHEREMAININGWAVELENGTHSFORTHEMULTIWAVELENGTHCONNECTIVITYPATHMETHODTHISMETHODELIMINATESSEVERALWAVELENGTHCONVERTERS,ANDITSIMPLIESNODEDESIGNANDWAVELENGTHMANAGEMENTACONSEQUENCETHATALSONEEDSTOBEADDRESSEDISPROTECTIONSTRATEGY,ATTHEBERLEVELASWELLASATTHEWAVELENGTHLEVELDUETOSEVEREDEGRADATIONORCOMPONENTHARDFAILUREPROTECTIONMAYBESIMPLEORCOMPLEX,DEPENDINGONTHEADAPTEDPROTECTIONSTRATEGY,11,11,1N,ANDSOONINDWDM,ANOTHERISSUEHASAROSE,NAMELYWAVELENGTHCOLLISIONINTRADITIONALSINGLEWAVELENGTHNETWORKS,WAVELENGTHCOLLISIONHASNOTBEENANISSUESINCETHEOPTICALCHANNELWASONLYONEAT1,310ORAT1,550NMTHUS,MOVINGTHISCHANNELFROMONEBERTOANOTHER,ITWASASTRAIGHTFORWARDOPERATION,ASLONGASAPROTECTIONBERWASAVAILABLEINDWDM,WHEREONESYSTEMINONEDOMAINISINTERCONNECTEDWITHASYSTEMINANOTHERDOMAINWHEREDOMAINSMAYBEOPERATEDBYDIFFERENTNETWORKPROVIDERS,WAVELENGTHCOLLISIONMAYOCCUR,FIG85,WAVELENGTHCONVERSIONISNEEDEDANDALSOWAVELENGTHMANAGEMENTOVERTHECOMPLETEENDTOENDPATHHERE,WAVELENGTHCOLLISIONISDENEDASTHEACTIONBYWHICHONEOPTICALCHANNELASSOCIATEDWITHAPARTICULARWAVELENGTHOVERANETWORKB2B1SUBNETWORKFIG85SOMESAMEWAVELENGTHLIGHTPATHSDOMAINMAYOVERLAPOVERONEORMORELINKSCAUSINGWAVELENGTHCOLLISIONA1A284TRAFCMANAGEMENT177LINKISSWITCHEDFROMLINKATOLINKB,WHEREINLINKBTHESAMEWAVELENGTHISALREADYINUSEFORADIFFERENTPATHTHISDENITIONISEXTENDABLETOMORETHANONEWAVELENGTHASARESULT,ASUBSTANTIALEFFORTHASBEENSPENTTODETERMINETHEBLOCKINGPROBABILITYFORDIFFERENTNETWORKTOPOLOGIES,NODECOMPLEXITIES,ANDTRAFCCHARACTERISTICSANDALSOUNDERSTATICAND/ORDYNAMICCONDITIONSINTHISPURSUE,SEVERALALGORITHMSWEREDEVELOPEDTOESTABLISHTHERULESTHATOPTIMIZEWAVELENGTHASSIGNMENTPROCEDURESANDTHUSTRAFCROUTINGANDNETWORKTHROUGHPUT612831PATHSWITHROADMSWDMOPTICALPOINTTOPOINT,MESHORRINGNETWORKSHAVENODESTHATARECAPABLEOFDROPINGANDADDINGWAVELENGTHS,HENCEKNOWNASOPTICALADDDROPMULTIPLEXINGNODESOADMTHEADDED/DROPPEDWAVELENGTHSCARRYTRAFCTOBEDELIVEREDTOCUSTOMERSATTHELOCATIONOFTHEOADMCURRENTLY,THISISACCOMPLISHEDBYDESIGNATINGAPRIORIWHICHWAVELENGTHSOFTHEGRIDISTOBEDROPPEDASWELLASTHENUMBEROFWAVELENGTHSDEPENDINGONAPPLICATION,FROM1TO4,THISISKNOWNASXEDOADMCONGURABILITYTHENEXTGENERATIONINTELLIGENTNETWORKHOWEVERNEEDSTOBEABLETODROPANDADDEXIBLETRAFC,ANDTHUSOADMNODESNEEDTOBERECONGURABLEASDESCRIBEDIN13THATIS,OADMNODESMUSTBEABLETOBEPROGRAMEDEITHERLOCALLYORREMOTELYANDBEABLETODROPANDADDFROM1TONWAVELENGTHS,ASNEEDARISESSUCHNODESAREKNOWNASRECONGURABLEOADMSROADMHOWEVER,BECAUSEOFTHEDYNAMICNATUREOFRECONGURABILITY,ROADMSNEEDTOBEFAST,RELIABLE,ANDVERIABLEWESHOULDALSOPOINTOUTTHATMESHNETWORKSWITHROADMSADDANADDITIONALLEVELOFCOMPLEXITYONTHEPATHORROUTENDINGALGORITHMSBECAUSEWAVELENGTHSTHATAREAVAILABLEFORESTABLISHINGCONNECTIVITYMAYHAVETOBEUSEDBYROADMSANDTHUSTHENUMBEROFWAVELENGTHSFORENDTOENDCONNECTIVITYNEEDTOBERECALCULATEDADDITIONALLY,RECONGURABILITYADDSTONODEDESIGNCOMPLEXITYBECAUSECERTAINRECONGURABLEORREASSIGNEDWAVELENGTHSAREDROPPEDANDADDEDINSTEADOFCONTINUINGTHROUGHORVICEVERSATHUS,THISMAYREQUIREOPTICALPOWERBUDGETRECALCULATIONANDWAVELENGTHEQUALIZATIONANDDISPERSIONCOMPENSATIONANOTHERNODECOMPLEXITYISADDEDIFATTHEROADMCERTAINWAVELENGTHSAREREASSIGNEDTOBEDROPPEDANDADDEDINORDERTOCARRYMULTIPLEXEDTRAFCSUCHASSONET/SDH,INWHICHSOMEVTSNEEDTOPASSTHROUGHHOWEVER,THISISSIMPLIEDIFTRAFCISPACKETIZEDOPTIMIZINGTRAFCEFCIENCYFORDIFFERENTTRAFCTYPESISTHESUBJECTOFCURRENTRESEARCH84TRAFCMANAGEMENTTRAFCMANAGEMENTISRELATEDTOCLIENTTRAFCANDTHEREFORE,ALTHOUGHRELATEDTOBANDWIDTHMANAGEMENT,HASMORESPECICTASKSTOPERFORMFOREXAMPLE,ALTHOUGHBANDWIDTHMANAGEMENTADDRESSESTHEDISTRIBUTIONOFTRAFCEVENLYOVERNETWORK,ALSOKNOWNASBANDWIDTHBALANCING,TRAFCMANAGEMENTISMORECONCERNEDWITHCLIENTTRAFCSOTHATITMEETSTHEEXPECTEDQUALITYOFSERVICE,EXPECTEDREALTIMEDELIVERY,ANDALSOCLIENTBANDWIDTHONDEMANDTRAFCMANAGEMENTASSURESTHATINCOMINGTRAFCISMONITORED,ITISPROPERLYCONNECTED,ANDITSQUALITYLEVELISMAINTAINEDTHISISACCOMPLISHEDBYPOLICINGINCOMINGCLIENTTRAFCATTHEEDGENODESASACONSEQUENCE,TRAFCPOLICINGREQUIRESCONTINUOUSMONITORINGFORTRAFCPARAMETERCOMPLIANCEWITHTHESERVICELEVELAGREEMENTSLA,ASWELLASMONITORINGFORCONNECTIONPARAMETERVIOLATIONS,ANDUSEREQUIPMENTMALFUNCTIONING,AFUNCTIONKNOWNINATMASCONNECTIONMONITORINGTHEATMFORUMANDTHEITUTHAVEDENEDPARAMETERSTOMAINTAINTHEAGREEDTRAFCQOSITHASALSODENEDALGORITHMSFORPOLICINGTHETRAFCATTHEUSERNETWORKINTERFACEUNIFORBOTHCONSTANTBITRATECBRANDVARIABLEBITRATEVBRTHISALGORITHMISKNOWNASTHEGENERICCELL1788TRAFCMANAGEMENTANDCONTROLRATEALGORITHMGCRATHEGCRAISIMPLEMENTEDWITHTHECONTINUOUSSTATELEAKYBUCKETANDITISBASEDONTWOPARAMETERSTHEINCREMENTIANDTHELIMITLTHEIPARAMETERAFFECTSTHECELLRATETHELPARAMETERAFFECTSTHECELLBURSTFOREXAMPLE,THEPARAMETERSUTILIZEDINATMFORTRAFCMANAGEMENTAREPEAKCELLRATEPCRFORCBRANDVBRCONNECTIONS,SUSTAINABLECELLRATESCRFORVBRCONNECTIONS,ANDMAXIMUMBURSTSIZEMBSFORVBRCONNECTIONSTHESEPARAMETERSAREPROVIDEDBYTHEUSERDURINGTHECONNECTIONADMISSIONCONTROLCACATUNIINADDITION,THEBURSTTOLERANCEBTPARAMETERPUTSARESTRICTIONONTHEADDITIONALTRAFCABOVETHESCR,BEFOREITISTAGGEDEXCESSIVETRAFC85CONGESTIONMANAGEMENTFAILURESANDSEVERECOMPONENTDEGRADATIONSCANBESTATISTICALLYPREDICTABLEACCORDINGTOMANUFACTURERSFAILUREINTIMEFITDATAHOWEVER,THEREAREALSOUNPREDICTABLEFAILURES,SUCHASBERCUTSEITHERWAY,FAILURESANDDEGRADATIONSCAUSESTATISTICALUCTUATIONSOFTRAFCOWINTHENETWORKINANATTEMPTTOBYPASSTHEFAULTTHUS,THEREISANITEPROBABILITYTHATTRAFCTHROUGHANODEORLINKREACHESTHEMAXIMUMCAPACITYESTABLISHINGACONGESTIONCONDITIONMANIFESTEDBYNODEORLINKOVERLOAD,BANDWIDTHLOST,OREVENNETWORKCRASHINGENERAL,CONGESTIONMANAGEMENTISDENEDASANETWORKELEMENTSTATEUNABLETOMEETTHENEGOTIATEDNETWORKPERFORMANCEANDQUALITYOFSERVICEQOSOBJECTIVESASSUCH,CONGESTIONMANAGEMENTISSERIOUSLYADDRESSEDINDWDM,CONGESTIONMANAGEMENTISVERYIMPORTANTBECAUSESEVERELYDEGRADEDCOMPONENTSORFAULTYNODESANDLINKSAFFECTAHUMONGOUSAMOUNTOFTRAFCTHEREFORE,TRAFCREROUTINGNEEDSTOBEEXECUTEDEXPEDIENTLYANDEFCIENTLYTHUS,CONGESTIONMANAGEMENTNEEDSTOCONSIDERTHETYPEOFFAULTASEACHFAULTINUENCESBANDWIDTHOWATADIFFERENTLEVEL,TYPESOFSERVICESSUPPORTEDBYTHENETWORKASEACHTRAFCTYPEHASDIFFERENTREQUIREMENTS,NETWORKTOPOLOGYASEACHTOPOLOGYHASDIFFERENTSERVICESURVIVABILITYCHARACTERISTICS,SIZEOFNETWORK,INBOTHBANDWIDTHCAPACITYANDNUMBEROFNODES,ANDINTERNETWORKINGASTHEOVERALLPATHMAYCROSSSEVERALNETWORKPROVIDERDOMAINS,EACHCONSISTINGOFNODESWITHDIFFERENTSYSTEMCAPABILITIES86ROUTINGALGORITHMSINDWDMOPTICALNETWORKS,ALIGHTPATHCONNECTSASOURCEWITHADESTINATIONANDITMAYCONSISTOFTHESAMEWAVELENGTHFROMONEENDTOTHEOTHERENDORITMAYCONSISTOFSEVERALCONCATENATEDWAVELENGTHS,WHEREBYAWAVELENGTHCHANGESTOANOTHERBYMEANSOFWAVELENGTHCONVERTERSAMESHNETWORKWITHMANYNODESHASALARGENUMBEROFPOSSIBLESOURCETODESTINATIONPATHSADWDMMESHTOPOLOGYMAYBETHOUGHTASTHESUPERPOSITIONOFMANYMESHSINGLEWAVELENGTHTOPOLOGIESINDWDMOPTICALMESHNETWORKS,ONEPATHMAYOVERLAPWITHANOTHERPATHOVERONEORMORELINKSTHISMAKESTHEROUTINGALGORITHMMORECOMPLEXASTHESAMEWAVELENGTHFROMTWODIFFERENTSOURCESCANNOTCOEXISTOVERTHESAMEBERLINKIFTHISOCCURS,CROSSTALKSEVERELYDEGRADESTHETWOCHANNELSSOMESOLUTIONSUSEPOLARIZATIONSTATESTOMINIMIZECROSSTALKBUTTHELINKMUSTBEABLETOMAINTAINTHETWOPOLARIZATIONSTATESOVERITSFULLLENGTHTHUS,ATSETUPTIME,THEREISANITEPROBABILITYOFWAVELENGTHBLOCKING,PARTICULARLYWHENWAVELENGTHSAREDYNAMICALLYASSIGNEDINORDERTOMINIMIZETHEBLOCKINGPROBABILITYEFCIENTLY,OPTICALNODESREQUIRESPECICCONGURATION17987DISCOVERYOFOPTICALNETWORKTOPOLOGYFEATURES,WAVELENGTHCONVERSIONSTRATEGY,ANDSWITCHINGCAPABILITIESTHISISACCOMPLISHEDWITHTHEUSEOFROUTINGANDWAVELENGTHASSIGNMENTRWAALGORITHMSRWAALGORITHMSARECLASSIEDASSTATICANDDYNAMIC14DYNAMICRWAALGORITHMSASSIGNANDREMOVELIGHTPATHSRANDOMLYACCORDINGTONETWORKCONNECTIONREQUESTS,TRAFCUTILIZATION,ANDCONGESTIONSTATESTOINCREASENETWORKBANDWIDTHPERFORMANCE,ANODEADVERTISESITSSTATUSANDWAVELENGTHAVAILABILITYTOOTHERNODESBYMEANSOFPACKETSSUCHASADDRESSABLE,SHARED,CHANNELIZED,ANDHYBRIDTHISINCLUDESGLOBALNETWORKSTATEPARAMETERSONLINKSWITHINTHENETWORK,ASWELLASLOCALNODESTATUSTWODYNAMICROUTINGALGORITHMSARETHEALTERNATEPATHROUTINGANDUNCONSTRAINEDPATHROUTINGALTERNATEPATHROUTINGASSUMESTHATEVERYNODESTORESTHERSTNSHORTESTANDPREDETERMINEDPATHSTOEACHDESTINATIONBYUTILIZINGGLOBALANDLOCALNODELINKINFORMATIONCONGESTIONISDETERMINEDINPARTBYTHENUMBEROFWAVELENGTHSAVAILABLEPERPATHORLINKUNCONSTRAINEDROUTINGCONSIDERSALLPATHS,ANDITISBASEDONTHECOSTFUNCTIONOFALLLINKSWITHINTHENETWORKTODETERMINETHEOPTIMALENDTOENDPATHINGENERAL,DYNAMICROUTINGALGORITHMSPROCESSGLOBALNETWORKSTATEINFORMATIONTODETERMINETHEENDTOENDPATHALTERNATIVELY,THEDEECTIONORALTERNATEROUTINGALGORITHMISLIMITEDTOSTATEINFORMATIONFROMNEIGHBORINGNODESONLY,INWHICHCASELINKSARECHOSENONAHOPBYHOPBASISACCORDINGTOIT,ATEACHINTERMEDIATENODE,ACONTROLMESSAGEISPROCESSEDBEFOREBEINGFORWARDEDTOTHENEXTNODETHISCONTINUESONEHOPATATIMEUNTILTHEDESTINATIONNODECOMPLETESTHENALPROCESSOFTHECONTROLMESSAGEANDSENDSITBACKTOTHESOURCENODEDECISIONSONWAVELENGTHASSIGNMENTAREBASEDONTHESHORTESTPATHRST,FOLLOWEDBYALTERNATIVEROUTECONSIDERATIONSIFASPECICWAVELENGTHISUNAVAILABLETHELEASTCONGESTEDDEECTIONROUTINGSCHEMECHOOSESFROMALISTOFOUTGOINGLINKSBASEDONTHELARGESTNUMBEROFFEASIBLEWAVELENGTHSTHESHORTESTPATHRSTMETHODRESULTSINLOWERBLOCKINGWITHLESSTRAFCWHILEALEASTCONGESTEDPOLICYRESULTSINLOWERBLOCKINGATHEAVIERTRAFCLOADSTHOSEROUTINGSCHEMESAREAPPLICABLETOSINGLEBERMESHTOPOLOGY,ASWELLASMULTIBERNETWORKS87DISCOVERYOFOPTICALNETWORKTOPOLOGYWAVELENGTHASSIGNMENTALGORITHMSPROVIDETHEOPTIMALWAVELENGTHCONNECTIVITYTOACONNECTIONREQUESTWAVELENGTHASSIGNMENTISCLASSIEDASSTATICANDDYNAMICFORSTATICWAVELENGTHASSIGNMENT,ASEQUENTIALGRAPHCOLORINGAPPROACHISUSEDTONDTHEMINIMUMWAVELENGTHSCOLORSFOROVERAPATHFORTHEOPTICALNETWORKTOROUTEOPTICALCHANNELS,THEPHYSICALANDTHELOGICALLAYERTOPOLOGYOFTHENETWORKMUSTBEKNOWNTHATIS,EACHSWITCHINGNODEMUSTKNOWTHECHARACTERISTICSOFTHEADJACENTSWITCHINGNODESASWELLASTHEINTERCONNECTEDPORTSAMONGADJACENTSWITCHINGNODESTYPICALLY,THISISACCOMPLISHEDWITHSELFDISCOVERYPROTOCOLSSUCHPROTOCOLSUSESIGNALINGMESSAGESTHATLEARNANDSHARENODECONGURATIONANDTRAFCINFORMATIONUSINGSIGNALINGMESSAGES,APROTOCOLENABLESTHENODESTOESTABLISHANDMAINTAINANADJACENCYDATABASETHATREECTSTHESTATEOFTHENETWORKABOUTANODETHESEDATABASESAREREFRESHEDWHENEVERACHANGEINT
温馨提示
- 1. 本站所有资源如无特殊说明,都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
- 2. 本站的文档不包含任何第三方提供的附件图纸等,如果需要附件,请联系上传者。文件的所有权益归上传用户所有。
- 3. 本站RAR压缩包中若带图纸,网页内容里面会有图纸预览,若没有图纸预览就没有图纸。
- 4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
- 5. 人人文库网仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对用户上传分享的文档内容本身不做任何修改或编辑,并不能对任何下载内容负责。
- 6. 下载文件中如有侵权或不适当内容,请与我们联系,我们立即纠正。
- 7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。
最新文档
- 2024年饭店转让合同常用版(三篇)
- 2024年借款保证合同范文(四篇)
- 2024年个人货物买卖合同标准范本(3篇)
- 2024年股权转让合同范本(3篇)
- 2024年设备技术服务合同标准版本(二篇)
- 展厅合作协议
- 仓库消防应急预案火灾预防措施、应急处理与疏散办法
- 2024年保洁临时工劳动合同(二篇)
- 2024年技术入股的协议(二篇)
- 2024年工程居间合同格式版(三篇)
- 线束加工外观的检验规范
- 《鼓励孩子的方法》课件
- 模具设计精益生产技术培训
- 011(1)-《社会保险人员减员申报表》
- 医美护理课件
- 《系统集成项目管理工程师教程》(教材解读)
- 预防校园欺凌法治知识竞答题库及答案
- (完整版)北师大小学数学四年级下册用方程解应用题练习题
- 医院审批流程优化方案
- 充电桩招标文件:技术要求
- 生产异常处理时效及流程图
评论
0/150
提交评论