ETSI EN 300 462-3-1 V1.1.1 (1998-05)

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Transmission and Multiplexing (TM); Generic requirements for synchronization networks; Part 3-1: The control of jitter and wander within synchronization networks33.040.20Prenosni sistemTransmission systemsICS:Ta slovenski standard je istoveten z:EN 300 462-3-1 Version 1.1.1SIST EN 300 462-3-1 V1.1.1:2003en01-december-2003SIST EN 300 462-3-1 V1.1.1:2003SLOVENSKI
STANDARD



SIST EN 300 462-3-1 V1.1.1:2003



EN 300 462-3-1 V1.1.1 (1998-05)European Standard (Telecommunications series)Transmission and Multiplexing (TM);Generic requirements for synchronization networks;Part 3-1: The control of jitter and wander withinsynchronization networksSIST EN 300 462-3-1 V1.1.1:2003



ETSIEN 300 462-3-1 V1.1.1 (1998-05)2ReferenceREN/TM-03017-3-1 (4a0r9ico.PDF)KeywordsSynchronization, transmission, networkETSIPostal addressF-06921 Sophia Antipolis Cedex - FRANCEOffice address650 Route des Lucioles - Sophia AntipolisValbonne - FRANCETel.: +33 4 92 94 42 00
Fax: +33 4 93 65 47 16Siret N° 348 623 562 00017 - NAF 742 CAssociation à but non lucratif enregistrée à laSous-Préfecture de Grasse (06) N° 7803/88Internetsecretariat@etsi.frhttp://www.etsi.frhttp://www.etsi.orgCopyright NotificationNo part may be reproduced except as authorized by written permission.The copyright and the foregoing restriction extend to reproduction in all media.© European Telecommunications Standards Institute 1998.All rights reserved.SIST EN 300 462-3-1 V1.1.1:2003



ETSIEN 300 462-3-1 V1.1.1 (1998-05)3ContentsIntellectual Property Rights.4Foreword.41Scope.62Normative references.63Definitions, symbols and abbreviations.73.1Definitions.73.2Symbols.73.3Abbreviations.74Basic philosophy for the control of jitter and wander.75Synchronization interfaces.86Synchronization reference network.97Network limits for jitter and wander at synchronization interfaces.97.1Network limits for jitter.107.2Network limits for wander.107.2.1Network limits for wander at PRC outputs.117.2.2Network limits for wander at SSU outputs.127.2.3Network limits for wander at SEC outputs.147.2.4Network limits for wander at PDH distribution outputs.15Annex A (normative):Anti-aliasing filter to be used for the measurement of MTIE andTDEV.17A.1Measurement philosophy.17A.2Filter specification, sampling time and measurement interval.17Annex B (informative):Network model underlying the network limit.19B.1Introduction.19B.2Considerations on the network model.19B.3Information regarding the simulations.21History.23SIST EN 300 462-3-1 V1.1.1:2003



ETSIEN 300 462-3-1 V1.1.1 (1998-05)4Intellectual Property RightsIPRs essential or potentially essential to the present document may have been declared to ETSI. The informationpertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be foundin ETR 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in respect ofETSI standards", which is available free of charge from the ETSI Secretariat. Latest updates are available on the ETSIWeb server (http://www.etsi.fr/ipr or http://www.etsi.org/ipr).Pursuant to the ETSI Interim IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. Noguarantee can be given as to the existence of other IPRs not referenced in ETR 314 (or the updates on the ETSI Webserver) which are, or may be, or may become, essential to the present document.ForewordThis European Standard (Telecommunications series) has been produced by the Transmission and Multiplexing (TM)Technical Committee.The present document has been produced to provide requirements for synchronization networks that are compatible withthe performance requirements of digital networks. It is one of a family of documents covering various aspects ofsynchronization networks:Part 1-1:"Definitions and terminology for synchronization networks";Part 2-1:"Synchronization network architecture";Part 3-1:"The control of jitter and wander within synchronization networks";Part 4-1:"Timing characteristics of slave clocks suitable for synchronization supply to Synchronous DigitalHierarchy (SDH) and Plesiochronous Digital Hierarchy (PDH) equipment";Part 4-2:"Timing characteristics of slave clocks suitable for synchronization supply to Synchronous DigitalHierarchy (SDH) and Plesiochronous Digital Hierarchy (PDH) equipment ImplementationConformance (ICS) Statement";Part 5-1:"Timing characteristics of slave clocks suitable for operation in Synchronous Digital Hierarchy(SDH) equipment";Part 6-1:"Timing characteristics of primary reference clocks";Part 6-2:"Timing characteristics of primary reference clocks Implementation Conformance (ICS)Statement";Part 7-1:"Timing characteristics of slave clocks suitable for synchronization supply to equipment in localnode applications".Parts 1-1, 2-1, 3-1 and 5-1 have previously been published as ETS 300 462 Parts 1, 2, 3 and 5, respectively.Additionally, parts 4-1 and 6-1 completed the Voting phase of the Two Step Approval procedure as ETS 300 462 Parts4 and 6, respectively.It was decided to prepare ICS proformas for several of the parts and this necessitated a re-numbering of the individualdocument parts. It was also decided to create a new part 7-1.This in turn led to a need to re-publish new versions of all six parts of the original ETS. At the same time, theopportunity was taken to convert the document type to EN.This has involved no technical change to any of the documents. However part 5-1 has been modified, due to editorialerrors which appeared in ETS 300 462-5.SIST EN 300 462-3-1 V1.1.1:2003



ETSIEN 300 462-3-1 V1.1.1 (1998-05)5Transposition datesDate of adoption3 January 1997Date of latest announcement of this ETS (doa):30 April 1997Date of latest publication of new National Standardor endorsement of this ETS (dop/e):31 October 1997Date of withdrawal of any conflicting National Standard (dow):31 October 1997NOTE:The above transposition table is the original table from ETS 300 462-3 (January 1997, see History).SIST EN 300 462-3-1 V1.1.1:2003



ETSIEN 300 462-3-1 V1.1.1 (1998-05)61ScopeThe present document outlines requirements for the control of jitter and wander within synchronization Networks thatare constructed according to the architectural principles described in EN 300 462-2-1 [2]. A synchronization networkthat complies with the network limits for jitter and wander specified in the present document will be suitable for thesynchronization of Synchronous Digital Hierarchy (SDH) and Public Switched Telephone Network (PSTN) networks. Itcombines the short term stability requirements of SDH networks with the long term stability requirements of the PSTN.The values specified in the present document refer to the design of new synchronization networks. They do notnecessarily represent the performance of existing PSTN synchronization networks.The network limits specified in the present document form the network requirements from which the clock specificationsin EN 300 462-4-1 [3], EN 300 462-5-1 [4] and EN 300 462-6-1 [5] have been derived.2Normative referencesThe following documents contain provisions which, through reference in this text, constitute provisions of the presentdocument.· References are either specific (identified by date of publication, edition number, version number, etc.) ornon-specific.· For a specific reference, subsequent revisions do not apply.· For a non-specific reference, subsequent revisions do apply.· A non-specific reference to an ETS shall also be taken to refer to later versions published as an EN with the samenumber.[1]EN 300 462-1-1: "Transmission and Multiplexing (TM); Generic requirements for synchronizationnetworks; Part 1-1: Definitions and terminology for synchronization networks".[2]EN 300 462-2-1: "Transmission and Multiplexing (TM); Generic requirements for synchronizationnetworks; Part 2-1: Synchronization network architecture".[3]EN 300 462-4-1: "Transmission and Multiplexing (TM); Generic requirements for synchronizationnetworks; Part 4-1: Timing characteristics of slave clocks suitable for synchronization supply toSynchronous Digital Hierarchy (SDH) and Plesiochronous Digital Hierarchy (PDH) equipment".[4]EN 300 462-5-1: "Transmission and Multiplexing (TM); Generic requirements for synchronizationnetworks; Part 5-1: Timing characteristics of slave clocks suitable for operation in SynchronousDigital Hierarchy (SDH) equipment".[5]EN 300 462-6-1: "Transmission and Multiplexing (TM); Generic requirements for synchronizationnetworks; Part 6-1: Timing characteristics of primary reference clocks".[6]ITU-T Recommendation G.822: "Controlled slip rate objectives on an international digitalconnection".[7]ITU-T Recommendation G.823: "The control of jitter and wander within digital networks whichare based on the 2 048 kbit/s hierarchy".[8]ITU-T Recommendation O.171: "Timing jitter measuring equipment for digital systems".[9]ITU-T Recommendation G.783: "Characteristics of synchronous digital hierarchy (SDH)equipment functional blocks".SIST EN 300 462-3-1 V1.1.1:2003



ETSIEN 300 462-3-1 V1.1.1 (1998-05)73Definitions, symbols and abbreviations3.1DefinitionsFor the purposes of the present document, the definitions given in EN 300 462-1-1 [1] apply.3.2SymbolsFor the purposes of the present document the symbols and diagrammatic conventions described in EN 300 462-1-1 [1]apply.3.3AbbreviationsFor the purposes of the present document the abbreviations given in EN 300 462-1-1 [1], together with the following,apply:MTIEMaximum Time Interval ErrorPDHPlesiochronous Digital HierarchyPSTNPublic Switched Telephone NetworkPRCPrimary Reference ClockSDHSynchronous Digital HierarchySECSDH Equipment ClockSSUSynchronization Supply UnitSTM-NSynchronous Transport Module, level NTDEVTime DEViationUTCUniversal Time Co-ordinated4Basic philosophy for the control of jitter and wanderThe present multi-part document describes the synchronization network as a logically distinct network layer with its ownplanning rules and performance requirements. The philosophy for the control of jitter and wander in the synchronizationnetwork layer is the same as applied to the payload carrying layers of the transport network, which can be found inITU-T Recommendation G.823 [7]. It is based on the need to recommend a maximum network limit that should not beexceeded at any synchronization interface. This network limit represents the worst case accumulation of jitter andwander within the synchronization network reference chain shown in figure 5 of EN 300 462-2-1 [2]. The main purposefor defining a network limit is that it provides the maximum amount of jitter and wander that any synchronizationelement in the network may experience at its input, since the network limit should not be exceeded at the output of asynchronization element anywhere in the network. The network limits therefore provide indirectly the requirements forthe lower limit of maximum tolerable jitter and wander at the input of synchronization elements.The wander tolerance of the large installed base of 64 kbit/s digital switches, i.e. the differential wander that a switchwill tolerate before giving rise to controlled slip, together with the slip performance objectives stated in ITU-TRecommendation G.822 [6], have to be respected when introducing new transport technologies in the network. Thisdifferential wander is the cumulative effect of wander in the synchronization network and the wander that the transportof the data between switches may introduce. In the case of SDH, in most implementations, the latter is dependent on thewander that the SDH network elements experience at their synchronization inputs. The wander in a synchronizationnetwork that is also suitable for the synchronization of SDH therefore needs to be controlled to a level that is compatiblewith the slip performance objectives of the 64 kbit/s switched network.It should be noted that the implication of the network limit definition is, that in practical networks the jitter and wandervalues at most synchronization interfaces should be well within the network limits, because the network limits will onlyappear at the end of a synchronization chain that is as long as the reference chain.SIST EN 300 462-3-1 V1.1.1:2003



ETSIEN 300 462-3-1 V1.1.1 (1998-05)85Synchronization interfacesThe synchronization interfaces that are specified in the present document are depicted in figure 1. This figure is anexpanded version of figure 6 of EN 300 462-2-1 [2] showing examples of actual physical interfaces that may appear insynchronization networks. Universal Time Co-ordinated (UTC) is indicated in the figure as the reference relative towhich all network limits are specified. Because of the way it is defined, there is no physical entity or interface associatedwith UTC. Two alternative synchronization distribution methods may be used between Synchronization Supply Unit(SSUs), and between Primary Reference Clock (PRC) and SSUs. SDH distribution makes use of the SDH section layerand may be a cascade of sections with at most 20 intermediate SDH network elements, each containing an SDHEquipment Clock (SEC). Plesiochronous Digital Hierarchy (PDH) distribution makes use of a 2 Mbit/s PDH path thatmay be traversing a number of intermediate PDH multiplexing stages and PDH line systems. These are not shownexplicitly, because they do not contain clocks that are subject to the present document. SSUG.812 SSUG.812Synchronization interface at a PDH synchronization distribution output for which the network limit appliesSynchronization interface at a SEC output
for which the networklimit appliesSynchronization interface at a SSU output for which the network limit appliesSynchronization interface at a PRC output
for which the networklimit applies.Note 1.Note: The maximum number ofclocks in these chains is specifiedin EN 300 462-2-1 [2]NoteNoteNoteFigure 1: Synchronization reference chain showing where the network limits applyFigure 1 shows that four types of synchronization interfaces can be distinguished in the synchronization network:-synchronization interfaces at PRC outputs;SIST EN 300 462-3-1 V1.1.1:2003



ETSIEN 300 462-3-1 V1.1.1 (1998-05)9-synchronization interfaces at SSU outputs;-synchronization interfaces at SEC outputs;-synchronization interfaces at PDH distribution outputs.The present document therefore provides four sets of network limit requirements, one for each type of interface.6Synchronization reference networkThe synchronization reference chain defined in figure 5 of EN 300 462-2-1 [2] has to support not only a homogeneousSDH transport network, to which the transport network will evolve sooner or later, but also the evolution towards an allSDH transport network. In the transitional period, a mixed situation will exist where data paths may traverse both PDHand SDH sub-networks. The additional PDH/SDH mappings give rise to an increase of the wander that the data path isexperiencing because the wander that appears at the output of one SDH island is passed on transparently throughsubsequent islands via the asynchronous mapping process. It is therefore the transitional period which puts the moststringent requirements on the performance of the synchronization network.To provide for consistency between the specifications of the individual synchronization elements and the network limitsan iterative process has been followed. The accumulation of wander in the synchronization reference network has beencalculated based on a set of assumptions on:-the number and performance of individual synchronization elements;-the number and size of transients in the synchronization network;-the level of diurnal wander.The resulting quality of the synchronization network has then been applied to a reference model for the data path of foursynchronous islands. Subsequently, the set of assumptions has been varied until a combination was found that met therequirement for the average differential wander experienced by a slip buffer terminated equipment (e.g. a 64 kbit/sexchange) of less than 18 ms measured over one day. The assumptions that were found to meet this requirement aredocumented in annex B.It is stressed however that many other combinations of assumptions are conceivable that will comply with the networklimits resulting from the set given in annex B. These are elaborated in this informative annex for guidance only.Provided these assumptions are fulfilled, the 18 ms wander limit will be met also across multiple operator domains.A network operator may use a different set of rules, e.g. with a different number of SSUs and other assumptions aboutthe transients in the synchronization chain, provided the synchronization network limits for jitter and wander specified inthe present document are adhered to.7Network limits for jitter and wander at synchronizationinterfacesThe specification of network limits for synchronization interfaces is primarily intended to reflect the results of atheoretical analysis of the worst case accumulation of jitter and wander in a synchronization network. These values thenserve to specify tolerance requirements for synchronization equipment. It should, however, also be possible to verifythrough measurements in a real network that a particular interface does not exceed the specified limits. The location ofthe interface in the synchronization chain of that network determines what margin may be expected with reference to thenetwork limits.As shown in figure 1, an SSU may receive its timing via SDH or PDH distribution. The network limit at the output ofthese distribution chains represents the amount of jitter and wander that an SSU may experience at its input. Since thereis more jitter allowed at PDH interfaces than at SDH Synchronous Transport Module, level N (STM-N) interfaces, thenetwork limit for the PDH distribution outputs represents the worst case that the SSU should tolerate at its inputs. Thejitter and wander tolerance of a SEC should be (at least) the amount of jitter at the input of the last SEC of asynchronization chain. Since the contribution of the last SEC in the chain to the network limit at SEC outputs- that is theSIST EN 300 462-3-1 V1.1.1:2003



ETSIEN 300 462-3-1 V1.1.1 (1998-05)10amount of jitter and wander that may be expected at the output of the last SEC of the chain - is small, the network limitin the SEC output can be used as the jitter and wander tolerance requirement for a SEC.From the large number of available timing characteristics a subset has been selected to constrain both thestandardization as well as the operational verification effort. The selected characteristics are considered to providesufficient information to ensure satisfactory operation of PSTN and SDH networks.7.1Network limits for jitterThe maximum allowable high frequency noise components of a timing signal are specified by the network limits forjitter.The theoretical arra
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