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RFC-130 NetworknimerProtocol Versionroso s.dt Marchr992 0 0 0 0 - 1. S 0 r isc - I Thi alocument constitutescaogrmalspecification@ofghedNetworko imedProtogold(NTP)Versiond whichdiscusseddocsynchronizedimekeepingamongoosetwofali ributeddimedserver, andcclient defines thearchitectures, calgorithms, entities guideprotocolsaiseddyNTP andisintended primarily for( mplementors.oAocompanionodocumento MJL91a]o ummarizes theo equirements,canalytical models, algorithmicanalys andperformanceminderoypicalonternetconditionsAnotherdocument [MIL91b] describesohe«NTP timescalepandørrelationshippo@thero andardoimescalesmowo use NTP was firstodescribedoinoRFC-9580[MIJ_85c],obut hasosinceqevolvedoinosignificantoways culminatingandheonostcrecen NTP Versiongalescribedono 1119{{MIL89].otdiscbuilt ondhe Internet(Protocolo IP) [DAR81a]and@UserDatagramo rotocol (UDP) [POS80], which provideo connectionlessoransport mechanism; however, it isoeadilyadaptabledo@ther protocolosui es NT is@volvedoromahedimedProtocoloPOS83b]candoheoCM imestampo essageQDAR81b],dutos pathsonvolvingonultiple gateways chighlyci persivealelays andoinreliablemets. Theoserviceœenvironment consistsoofothecimplementationomodeloandoserviceomodelodescribedin Section@2.d'heomplementationonodelosbasedonao ultiple-processoperatingsystemarchitecture, althoughotherarchitecturescouldbeaisedaas well.o hecserviceo odelsbasedoncoeturnable-time designowhichodependsoonlyoono easuredoclockooff et butodoes noto equineo eliableomessage delivery.ot hecsynchronization subnetaises ao elf-organizing, chierarchical-master-slavecconfigura tioff, with synchronization paths determined bycamminimum-weightcspanningoree. Whileomulti le master (primarycservers)onay@exist, dheredsmocrequirement forcan election protocol NTP tselfgsalescribedandSection3.dt providesche protocolamechanismsdocsynchronizedi edin 0 0 y principleoopreci ons inoheorderofmanoseconds whilepreservingomnon-ambiguous dateovellonto themextcentury. he protocolincludes provisionso ocspecifythexcharacteri icscandcesti atedhe errorinfithedocaloclocksandotheotimeoserver toowhithoitomaybeo ynchronized. dtoalsoincludes poovi ons or@operationovithcamnumber of mutually suspicious, hierarchicallyadistributed primar rdferdnotetsourcessualcs radio-synchronizedælocks. S 0 S Sectionelalescribesalgorithm usefuldor deglitchingandomoqthing@lock-offseto amplescollected oncacontinuousbas Mesecalgorithm @volveddromohosedsugges edindMIL85a], wererefine ascheo esultsoof experimentsodescribedcino MIL85b]canddfurtherœevolvedainderdypical@opera ing conditions over heoas hreecyears. noaddition, as theoesultaofexperiencedin@operatingamultiple server subnetsincludingo adioclockscato eversilesitesindhedJ.S. andowith@cuistotsindhedJ. . cand Europe, oeliablealgorithm ordselectinggood@locksdromopopulation@poss blyoincludingbroken oneschavedeenalevelopetidDEC89],d Lola]aindarealescribedonSectMM. Themaccuracies achievablebycNTPadependostronglycondhecprecision@ofahedocal-clockchardwar sl ando ringent controloof devicecand processdatencies Provi ons mustbedecludeddocadj the softwaredogical-clockdimecandofrequencydinoresponsedocorrections producedbyNTP.Sectiondh describesodocal-clockadesignœvolvedorom the Fuzzball implementationodescribeddino L83b] ando L88b].oThisodesignoincludesooffset- ewing,ofrequencyocompensationoandodeglitching Mills gent
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