SIST EN 300 462-2-1 V1.2.1:2003
(Main)Transmission and Multiplexing (TM); Generic requirements for synchronization networks; Part 2-1: Synchronization network architecture based on SDH networks
- Abstract
For the revision of EN 300 462-2-1. To be put in line with DEN/TM-01080, and also cover activities on network wide synchroniszation, and interaction between SASE and SDH NEs.
- Status
- Published
- Publication Date
- 30-Nov-2003
- Current Stage
- 6060 - National Implementation/Publication (Adopted Project)
- Start Date
- 01-Dec-2003
- Due Date
- 01-Dec-2003
- Completion Date
- 01-Dec-2003
SIST EN 300 462-2-1 V1.2.1:2003 is the SIST adoption of ETSI EN 300 462-2-1, a European Telecommunications Standard for synchronization networks based on SDH networks. It specifies the architectural principles, clock functions and distribution rules for designing synchronization networks for SDH and PDH environments, so engineers can plan timing for SDH equipment, gateway nodes and connected digital networks.
What does SIST EN 300 462-2-1 V1.2.1:2003 specify?
SIST EN 300 462-2-1 V1.2.1:2003 specifies the architectural principles that should be applied when designing synchronization networks for SDH and PDH networks. It supports synchronization for SDH networks and for digital switching networks such as PSTN that are connected to SDH.
The standard applies to new synchronization networks. It gives rules and guidance for how synchronization should be built, while leaving detailed timing characteristics to the companion parts of the EN 300 462 series and to EG 201793.
The document is organized into a foreword, clauses 1 to 10, and informative Annex A. Clause 4 covers synchronization methods, clauses 5 to 10 cover the clock functions, architecture, modes, reference chain, evolution and robustness, and Annex A gives a bibliography.
What are the key requirements of SIST EN 300 462-2-1 V1.2.1:2003?
Clock hierarchy and timing flow
Clause 4 establishes master-slave synchronization as the model for SDH networks. The hierarchy runs from the Primary Reference Clock (PRC) at the top, through slave clocks, down to the SDH Equipment Clock (SEC), and higher-quality clocks should not be synchronized from lower-quality clocks in holdover mode. In practice, this means timing must flow in one direction through the hierarchy.
Clause 4 also says timing between hierarchical node clocks should avoid intermediate pointer processing. The document points to recovering timing from a received STM-N signal or from a synchronization trail not supported by an SDH network. That matters because pointer adjustments can disturb the downstream timing seen by other network elements.
PRC, SSU and SEC functions
Clause 5 defines the logical functions of the PRC, the Synchronization Supply Unit (SSU) and the SEC. The PRC generates the master clock, the SSU selects among multiple inputs, filters jitter and short-term wander, and distributes timing inside a node, and the SEC selects and filters timing for outgoing SDH STM-N interfaces. For a designer, this section shows which function belongs at each level of the network.
Clause 5 also describes holdover behavior. When synchronization inputs fail, the SSU and the SEC use an internal oscillator to maintain frequency stability for a limited time. That is important in real networks because it tells operators how the node behaves during loss of reference.
Network architecture and modes
Clause 6 sets the target architecture. Within a node, timing distribution follows a logical star pattern around the highest hierarchical clock in that node. Between nodes, the architecture is tree-like, and all network element clocks must remain traceable to a PRC.
Clause 7 identifies four synchronization modes: synchronous, pseudo-synchronous, plesiochronous and asynchronous. These modes describe whether the network shares one PRC, several PRCs, or has lost usable synchronization. For operations teams, the mode helps explain when pointer adjustments are expected and when traffic may be at risk.
Reference chains, evolution and robustness
Clause 8 describes the synchronization network reference chain and gives planning limits for the worst-case chain. The practical message is to keep the tandem chain as short as possible and verify that the design still meets the short-term stability requirements.
Clause 9 covers evolution of SDH networks and the move from earlier synchronization plans. Clause 10 then adds robustness measures: redundant trails, reconfiguration using the Synchronization Status Message (SSM), and management support for fault detection and controlled reconfiguration. In practice, these clauses tell operators to provide alternate timing paths, monitor quality, and avoid timing loops.
What terms does SIST EN 300 462-2-1 V1.2.1:2003 define?
- Primary Reference Clock (PRC) - the top-level clock function that provides the master timing reference for a network or part of a network.
- Synchronization Supply Unit (SSU) - a node function that selects a timing source, filters it and distributes the resulting clock inside the node.
- SDH Equipment Clock (SEC) - the timing source used by SDH equipment for outgoing SDH interfaces.
- Synchronization Status Message (SSM) - a timing-quality marking carried in section overhead to show the quality of the selected reference.
- Stand-Alone Synchronization Equipment (SASE) - a separate synchronization unit that can provide the synchronization function outside an integrated network element.
- Optical Transport Network (OTN) - the transport network context discussed in clause 9, where timing transparency of payload transport is considered.
- Synchronous Digital Hierarchy (SDH) - the network family for which the architecture and timing rules are written.
Who uses SIST EN 300 462-2-1 V1.2.1:2003?
Synchronization engineers, SDH network planners and transmission equipment designers use this standard to define timing architecture and clock hierarchy. Network operators use it when planning PRC placement, designing synchronization trails, selecting alternate paths and managing holdover behavior.
It is also relevant to vendors integrating SSU, SEC or SASE functions into SDH network elements or PSTN switches. Buyers and quality managers use it to check whether a proposed design follows the synchronization architecture expected for SDH-based networks.
What changed in SIST EN 300 462-2-1 V1.2.1:2003 from the previous edition?
This edition revises part 2-1 in several sections to reflect work done in EG 201793 and the current status of synchronization networks. The scope note also says the revision was intended to align the document with DEN/TM-01080 and extend coverage to network-wide synchronization and the interaction between SASE and SDH NEs.
Which standards are used with SIST EN 300 462-2-1 V1.2.1:2003?
- EN 300 462-1-1 - provides the definitions and terminology used in clause 3.
- EN 300 462-3-1 - covers control of jitter and wander and is used for timing performance limits.
- EN 300 462-4-1 - gives timing characteristics for slave clocks for SDH and PDH equipment.
- EN 300 462-5-1 - gives timing characteristics for SECs.
- EN 300 462-6-1 - gives timing characteristics for PRCs.
- EN 300 462-7-1 - gives timing characteristics for slave clocks used in local node applications.
- EN 300 147 - provides the SDH multiplexing structure.
- EG 201793 - adds synchronization network engineering guidance and examples.
- EN 300 417-6-1 - provides synchronization layer functions and the SSM handling used in the architecture.
What does the SIST EN 300 462-2-1 V1.2.1:2003 document contain?
The document contains clause-level guidance on synchronization architecture rather than detailed component test limits. Figures show the SSU and SEC clock functions, intra-node and inter-node architecture, the reference chain and a reconfiguration example.
It also explains how SDH networks should be introduced and evolved, how OTN payload transport relates to timing transparency, and how robustness is improved through redundancy, SSM and management. Annex A gives an informative bibliography, including ITU-T Recommendation G.783.
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Frequently Asked Questions
SIST EN 300 462-2-1 V1.2.1:2003 is a standard published by the Slovenian Institute for Standardization (SIST). Its full title is "Transmission and Multiplexing (TM); Generic requirements for synchronization networks; Part 2-1: Synchronization network architecture based on SDH networks". This standard covers: For the revision of EN 300 462-2-1. To be put in line with DEN/TM-01080, and also cover activities on network wide synchroniszation, and interaction between SASE and SDH NEs.
For the revision of EN 300 462-2-1. To be put in line with DEN/TM-01080, and also cover activities on network wide synchroniszation, and interaction between SASE and SDH NEs.
SIST EN 300 462-2-1 V1.2.1:2003 is classified under the following ICS (International Classification for Standards) categories: 33.040.20 - Transmission systems. The ICS classification helps identify the subject area and facilitates finding related standards.
SIST EN 300 462-2-1 V1.2.1:2003 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Transmission and Multiplexing (TM); Generic requirements for synchronization networks; Part 2-1: Synchronization network architecture based on SDH networks33.040.20Prenosni sistemTransmission systemsICS:Ta slovenski standard je istoveten z:EN 300 462-2-1 Version 1.2.1SIST EN 300 462-2-1 V1.2.1:2003en01-december-2003SIST EN 300 462-2-1 V1.2.1:2003SLOVENSKI
STANDARD
ETSIEN300462-2-1V1.2.1(2002-06)EuropeanStandard(Telecommunicationsseries)TransmissionandMultiplexing(TM);Genericrequirementsforsynchronizationnetworks;Part2-1:SynchronizationnetworkarchitecturebasedonSDHnetworksSIST EN 300 462-2-1 V1.2.1:2003
ETSIETSIEN300462-2-1V1.2.1(2002-06)2ReferenceREN/TM-01092Keywordsarchitecture,SDH,synchronization,transmissionETSI650RoutedesLuciolesF-06921SophiaAntipolisCedex-FRANCETel.:+33492944200Fax:+33493654716SiretN°34862356200017-NAF742CAssociationàbutnonlucratifenregistréeàlaSous-PréfecturedeGrasse(06)N°7803/88ImportantnoticeIndividualcopiesofthepresentdocumentcanbedownloadedfrom:http://www.etsi.orgThepresentdocumentmaybemadeavailableinmorethanoneelectronicversionorinprint.Inanycaseofexistingorperceiveddifferenceincontentsbetweensuchversions,thereferenceversionisthePortableDocumentFormat(PDF).Incaseofdispute,thereferenceshallbetheprintingonETSIprintersofthePDFversionkeptonaspecificnetworkdrivewithinETSISecretariat.Usersofthepresentdocumentshouldbeawarethatthedocumentmaybesubjecttorevisionorchangeofstatus.InformationonthecurrentstatusofthisandotherETSIdocumentsisavailableathttp://portal.etsi.org/tb/status/status.aspIfyoufinderrorsinthepresentdocument,sendyourcommentto:editor@etsi.frCopyrightNotificationNopartmaybereproducedexceptasauthorizedbywrittenpermission.Thecopyrightandtheforegoingrestrictionextendtoreproductioninallmedia.©EuropeanTelecommunicationsStandardsInstitute2002.Allrightsreserved.DECTTM,PLUGTESTSTMandUMTSTMareTradeMarksofETSIregisteredforthebenefitofitsMembers.TIPHONTMandtheTIPHONlogoareTradeMarkscurrentlybeingregisteredbyETSIforthebenefitofitsMembers.3GPPTMisaTradeMarkofETSIregisteredforthebenefitofitsMembersandofthe3GPPOrganizationalPartners.SIST EN 300 462-2-1 V1.2.1:2003
ETSIETSIEN300462-2-1V1.2.1(2002-06)3ContentsIntellectualPropertyRights.4Foreword.41Scope.62References.63Definitionsandabbreviations.73.1Definitions.73.2Abbreviations.74Synchronizationmethods.75Functionaldescriptionofclocktypes.85.1PrimaryReferenceClock(PRC).85.2SynchronizationSupplyUnit(SSU).85.3SDHEquipmentClock(SEC).96Synchronizationnetworkarchitecture.107Synchronizationmodes.118Synchronizationnetworkreferencechain.129Synchronizationnetworkevolution.149.1SDHnetworks.149.2OpticalTransportNetworks.1410Synchronizationnetworkrobustness.1410.1General.1410.2Trailredundancy.1410.3Synchronizationstatusmessage.1510.4Management.15AnnexA(informative):Bibliography.16History.17SIST EN 300 462-2-1 V1.2.1:2003
ETSIETSIEN300462-2-1V1.2.1(2002-06)4IntellectualPropertyRightsIPRsessentialorpotentiallyessentialtothepresentdocumentmayhavebeendeclaredtoETSI.TheinformationpertainingtotheseessentialIPRs,ifany,ispubliclyavailableforETSImembersandnon-members,andcanbefoundinETSISR000314:"IntellectualPropertyRights(IPRs);Essential,orpotentiallyEssential,IPRsnotifiedtoETSIinrespectofETSIstandards",whichisavailablefromtheETSISecretariat.LatestupdatesareavailableontheETSIWebserver(http://webapp.etsi.org/IPR/home.asp).PursuanttotheETSIIPRPolicy,noinvestigation,includingIPRsearches,hasbeencarriedoutbyETSI.NoguaranteecanbegivenastotheexistenceofotherIPRsnotreferencedinSR000314(ortheupdatesontheETSIWebserver)whichare,ormaybe,ormaybecome,essentialtothepresentdocument.ForewordThisEuropeanStandard(Telecommunicationsseries)hasbeenproducedbyETSITechnicalCommitteeTransmissionandMultiplexing(TM).Thepresentdocumenthasbeenproducedtoproviderequirementsforsynchronizationnetworksthatarecompatiblewiththeperformancerequirementsofdigitalnetworks.Itisoneofafamilyofdocumentscoveringvariousaspectsofsynchronizationnetworks.Thepresentdocumentispart2-1ofamulti-partdeliverablecoveringgenericrequirementsforsynchronizationnetworks,asidentifiedbelow:Part1-1:"Definitionsandterminologyforsynchronizationnetworks";Part2-1:"SynchronizationnetworkarchitecturebasedonSDHnetworks";Part3-1:"Thecontrolofjitterandwanderwithinsynchronizationnetworks";Part4-1:"TimingcharacteristicsofslaveclockssuitableforsynchronizationsupplytoSynchronousDigitalHierarchy(SDH)andPlesiochronousDigitalHierarchy(PDH)equipment";Part4-2:"TimingcharacteristicsofslaveclockssuitableforsynchronizationsupplytoSynchronousDigitalHierarchy(SDH)andPlesiochronousDigitalHierarchy(PDH)equipment;ImplementationConformanceStatement(ICS)proformaspecification";Part5-1:"TimingcharacteristicsofslaveclockssuitableforoperationinSynchronousDigitalHierarchy(SDH)equipment";Part6-1:"Timingcharacteristicsofprimaryreferenceclocks";Part6-2:"Timingcharacteristicsofprimaryreferenceclocks;ImplementationConformanceStatement(ICS)proformaspecification";Part7-1:"Timingcharacteristicsofslaveclockssuitableforsynchronizationsupplytoequipmentinlocalnodeapplications".Part2-1hasbeenrevisedinseveralsectionswithregardtotheworkdoneinEG201793[7]andtoreflectthepresentstatusofsynchronizationnetworks.SIST EN 300 462-2-1 V1.2.1:2003
ETSIETSIEN300462-2-1V1.2.1(2002-06)5NationaltranspositiondatesDateofadoptionofthisEN:31May2002DateoflatestannouncementofthisEN(doa):31August2002DateoflatestpublicationofnewNationalStandardorendorsementofthisEN(dop/e):28February2003DateofwithdrawalofanyconflictingNationalStandard(dow):28February2003SIST EN 300 462-2-1 V1.2.1:2003
ETSIETSIEN300462-2-1V1.2.1(2002-06)61ScopeThepresentdocumentspecifiesthearchitecturalprinciplesthatshouldbeappliedforthedesignofsynchronizationnetworksthataresuitableforthesynchronizationofSynchronousDigitalHierarchy(SDH)andPlesiochronousDigitalHierarchy(PDH)networks.Itsupportstheconstructionofsynchronizationnetworksthatsupportboththeshort-termstabilityrequirementsofSDHnetworksandthelong-termstabilityrequirementsofdigitalswitchingnetworks(e.g.PSTN)connectedtotheSDHnetwork.Itappliestothedesignofnewsynchronizationnetworks.ItdoesnotcharacterizeexistingsynchronizationnetworksbasedonPDHnetworks.Thepresentdocumentspecifiestherulesandarchitecturalprinciplestheimplementationofsynchronizationnetworksshallfollow.ThisinformationissupplementedbyEG201793[7].Itgivesguidanceandexampleshowtheserulesandarchitecturalprinciplescanbeusedtosetupasynchronizationschemeforvariousnetworkconfigurations.2ReferencesThefollowingdocumentscontainprovisionswhich,throughreferenceinthistext,constituteprovisionsofthepresentdocument.• Referencesareeitherspecific(identifiedbydateofpublicationand/oreditionnumberorversionnumber)ornon-specific.• Foraspecificreference,subsequentrevisionsdonotapply.• Foranon-specificreference,thelatestversionapplies.[1]ETSIEN300462-1-1:"TransmissionandMultiplexing(TM);Genericrequirementsforsynchronizationnetworks;Part1-1:Definitionsandterminologyforsynchronizationnetworks".[2]ETSIEN300462-3-1:"TransmissionandMultiplexing(TM);Genericrequirementsforsynchronizationnetworks;Part3-1:Thecontrolofjitterandwanderwithinsynchronizationnetworks".[3]ETSIEN300147:"TransmissionandMultiplexing(TM);SynchronousDigitalHierarchy(SDH);Multiplexingstructure".[4]ETSIEN300462-5-1:"TransmissionandMultiplexing(TM);Genericrequirementsforsynchronizationnetworks;Part5-1:TimingcharacteristicsofslaveclockssuitableforoperationinSynchronousDigitalHierarchy(SDH)equipment".[5]ETSIEN300462-6-1:"TransmissionandMultiplexing(TM);Genericrequirementsforsynchronizationnetworks;Part6-1:Timingcharacteristicsofprimaryreferenceclocks".[6]ETSIEN300462-4-1:"TransmissionandMultiplexing(TM);Genericrequirementsforsynchronizationnetworks;Part4-1:TimingcharacteristicsofslaveclockssuitableforsynchronizationsupplytoSynchronousDigitalHierarchy(SDH)andPlesiochronousDigitalHierarchy(PDH)equipment".[7]ETSIEG201793:"TransmissionandMultiplexing(TM);Synchronizationnetworkengineering".[8]ETSIEN300462-7-1:"TransmissionandMultiplexing(TM);Genericrequirementsforsynchronizationnetworks;Part7-1:Timingcharacteristicsofslaveclockssuitableforsynchronizationsupplytoequipmentinlocalnodeapplications".[9]ETSIEN300417-6-1:"TransmissionandMultiplexing(TM);Genericrequirementsoftransportfunctionalityofequipment;Part6-1:Synchronizationlayerfunctions".SIST EN 300 462-2-1 V1.2.1:2003
ETSIETSIEN300462-2-1V1.2.1(2002-06)73Definitionsandabbreviations3.1DefinitionsForthepurposesofthepresentdocument,thetermsanddefinitionsgiveninEN300462-1-1[1]apply.3.2AbbreviationsForthepurposesofthepresentdocument,theabbreviationsdefinedinEN300462-1-1[1]andthefollowingapply:ADMAddDropMultiplexerAISAlarmIndicationSignalNENetworkElementOTNOpticalTransportNetworkPDHPlesiochronousDigitalHierarchyppmpartspermillionPRCPrimaryReferenceClockPSTNPublicSwitchedTelephoneNetworkSASEStand-AloneSynchronizationEquipmentSDHSynchronousDigitalHierarchySECSDHEquipmentClockSETGSDHEquipmentTimingGeneratorSETSSDHEquipmentTimingSourceSSUSynchronizationSupplyUnitSSMSynchronizationStatusMessageSTM-NSynchronousTransportModuleN4SynchronizationmethodsMaster-slavesynchronizationisappropriateforsynchronizingSDHnetworksandthefollowingmaterialoffersguidanceonusingthismethod.Master-slavesynchronizationusesahierarchyofclocksinwhicheachlevelofthehierarchyissynchronizedwithreferencetoahigherlevel.Therearefourqualitiesofclockinthesynchronizationhierarchyshownbelow:-PrimaryReferenceClock(PRC):seeEN300462-6-1[5];-slaveclock(transitnode):seeEN300462-4-1[6];-slaveclock(localnode):seeEN300462-7-1[8];-SDHEquipmentClock(SEC):seeEN300462-5-1[4].ThePRCisthehighestqualityhierarchicalclockandtheSECisthelowestqualityclock.Higherqualityclocksshallnotbesynchronizedbylowerqualityclocksinholdovermode,butclocksinholdovermodecanbeusedtosynchronizeclocksofthesamequality.Therearelimitsonthenumberofclocks,whichcanbeconnectedinasynchronizationdistributiontrail(seeclause8).Clockreferencesignalsaredistributedbetweenlevelsofthehierarchyviaadistributionnetwork,whichmayusethefacilitiesofthetransportnetwork.ThetransportnetworkmaycontainSECs.Thedistributionoftimingbetweenhierarchicalnodeclocksshallbeperformedusingamethod,whichavoidsintermediatepointerprocessing.Twopossiblemethodsareasfollows:a)recovertimingfromareceivedSynchronousTransportModuleN(STM-N)signal(thisavoidstheunpredictableeffectofapointeradjustmentonthedownstreamslaveclock);b)derivetimingfromasynchronizationtrailthatisnotsupportedbyaSDHnetwork.Themaster-slavemethodusesasingle-endedsynchronizationtechniquewiththeslaveclockselectingthesynchronizationtrailtobeusedasitsreferenceandchangingtoanalternativeiftheoriginaltrailfails.Thisisaunilateralcontrolscheme.SIST EN 300 462-2-1 V1.2.1:2003
ETSIETSIEN300462-2-1V1.2.1(2002-06)85Functionaldescriptionofclocktypes5.1PrimaryReferenceClock(PRC)ThePRCisalogicalfunctionconformingtotherequirementsofEN300462-6-1[5].Itgeneratesthemasterclockforanetworkorpartofanetwork.ThePRCequipmentmayeither:-implementitsownfreerunningoscillator(e.g.Caesiumtubeoscillator);or-beaslaveclockbeingsynchronizedtoahighaccuracyfreerunningclockbyterrestrialorsatelliteradiosignals(e.g.GPS).5.2SynchronizationSupplyUnit(SSU)ASSUisalogicalfunctionconformingtotherequirementsofEN300462-4-1[6]orEN300462-7-1[8].It:-acceptssynchronizationinputsfromanumberofsources;-selectsoneoftheseinputs;-f
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