ETSI EN 300 481 V1.2.2 (1997-12)

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.]DKWHYHTerminal Equipment (TE); Integrated Services Digital Network (ISDN); B-Channel Aggregation Unit (CAU); Procedures and terminal requirements35.180Terminalska in druga periferna oprema ITIT Terminal and other peripheral equipment33.080Digitalno omrežje z integriranimi storitvami (ISDN)Integrated Services Digital Network (ISDN)ICS:Ta slovenski standard je istoveten z:EN 300 481 Version 1.2.2SIST EN 300 481 V1.2.2:2003en01-december-2003SIST EN 300 481 V1.2.2:2003SLOVENSKI
STANDARD



SIST EN 300 481 V1.2.2:2003



European Telecommunications Standards InstituteEN 300 481 V1.2.2 (1997-12)European Standard (Telecommunications series)Terminal Equipment (TE);Integrated Services Digital Network (ISDN);B-Channel Aggregation Unit (CAU);Procedures and terminal requirementsSIST EN 300 481 V1.2.2:2003



EN 300 481 V1.2.2 (1997-12)2ReferenceREN/MTA-004123 (4gc00ipc.PDF)KeywordsISDN, multichannel, terminalETSI SecretariatPostal 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° 7803/88X.400c= fr; a=atlas; p=etsi; s=secretariatInternetsecretariat@etsi.frhttp://www.etsi.frCopyright 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 1997.All rights reserved.SIST EN 300 481 V1.2.2:2003



EN 300 481 V1.2.2 (1997-12)3ContentsIntellectual Property Rights.5Foreword.51Scope.62Normative references.63Definitions, symbols and abbreviations.73.1Definitions.73.2Symbols.83.3Abbreviations.84General.94.1Application of the present document.94.1.1Intercommunication of audiovisual equipments.94.1.1.1Case A.94.1.1.2Case B.94.1.1.3Case C.104.1.2Intercommunication of non-audiovisual equipments - Case D.104.2Definition of the modes of transmission on the Multiple Channel (MC) side.104.3General description of the aggregation process.144.4CAU functionality.145Choice of ISO Aggregation or H.244 Aggregation procedure.156H.244 Aggregation procedure.176.1Call control.176.1.1Initial channel.176.1.2Additional channels.176.2Channel synchronization.176.3In-band procedure using ITU-T Recommendation H.221 BAS codes.176.3.1Control of transfer rate.176.3.2Determination of the transfer-rate capabilities to be transmitted on the MC side.186.3.3Determination of the transfer-rate capabilities to be transmitted on the SC side.186.3.4Capability sets transmitted from a CAU.186.3.4.1Modification of SCE capset for forwarding towards MC side.196.3.4.2Modification of capset incoming from MC side for forwarding towards SCE.196.3.5Notification of change of Na.196.3.6Commands transmitted from a CAU.206.3.6.1Substitution of transfer rate commands.206.3.6.2Insertion and removal of [SM-comp] and [6B-H0-comp].206.3.6.3Insertion of [capex].206.3.6.4Insertion of [AggIN]*.206.4Transmission of user information by a CAU.207Initialization, mode/rate changing and fault recovery.217.1 Initialization.217.1.1Single channel side.217.1.1.1Incoming signal.217.1.1.2Outgoing signal.217.1.2Multi channel side, initial channel.227.1.2.1Incoming signal.227.1.2.2Outgoing signal.227.1.3Multi channel side, additional channels.227.2Change of transmission rate during a session.237.3Recovery from fault conditions.237.4Further mode changes.23SIST EN 300 481 V1.2.2:2003



EN 300 481 V1.2.2 (1997-12)48ISO Aggregation procedure.23Annex A (informative):Examples.24Annex B (informative):Example of SDL diagram for H.244 Aggregation initialization.28B.1H.244 Aggregation operation selected.28Annex C (informative):Comments on the modification of capsets and commands.29Annex D (informative):Bibliography.30History.31SIST EN 300 481 V1.2.2:2003



EN 300 481 V1.2.2 (1997-12)5Intellectual 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).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 onhttp://www.etsi.fr/ipr) which are, or may be, or may become, essential to the present document.ForewordThis European Standard (Telecommunications series) has been produced by ETSI Technical Committee TerminalEquipment (TE).National transposition datesDate of adoption of this EN: 5 December 1997Date of latest announcement of this EN (doa): 31 March 1997Date of latest publication of new National Standardor endorsement of this EN (dop/e): 30 September 1998Date of withdrawal of any conflicting National Standard (dow): 30 September 1998SIST EN 300 481 V1.2.2:2003



EN 300 481 V1.2.2 (1997-12)61ScopeThe present document defines protocols for the synchronization and aggregation of multiple Integrated Services DigitalNetwork (ISDN) channels at 64 kbit/s, these channels having a differential delay in the range of one second and with orwithout octet integrity structure. It also addresses the case of interworking with a digital network restricted to a rate of56 kbit/s. It is applicable to a wide range of user data transport up to 63 channels using ISO/IEC 13871 [1], but specialprovision is made for audiovisual systems according to ETS 300 144 [2], up to 24 channels; the aggregation may benetwork-based or associated with Customer Premises Equipment. The available operating modes (B1, B2, B3, H2)provide options with/without transmission-management overhead and user-data rates at or less than the exact multiplesof 64/56 kbit/s.The number of aggregated channels may be varied dynamically during a session. Procedures are given for dealing withfaults, including loss of channels and slip.Call control is outside the scope of the present document.2Normative referencesReferences may be made to:a)specific versions of publications (identified by date of publication, edition number, version number, etc.), inwhich case, subsequent revisions to the referenced document do not apply; orb)all versions up to and including the identified version (identified by "up to and including" before the versionidentity); orc)all versions subsequent to and including the identified version (identified by "onwards" following the versionidentity); ord)publications without mention of a specific version, in which case the latest version applies.A non-specific reference to an ETS shall also be taken to refer to later versions published as an EN with the samenumber.[1]ISO/IEC 13871: "Information Technology - Telecommunications and information exchangebetween systems - Private telecommunications networks - Digital channel aggregation".[2]ETS 300 144: "Integrated Services Digital Network (ISDN); Audiovisual services; Frame structurefor a 64 kbit/s to 1 920 kbit/s channel and associated syntax for inband signalling".[3]ETS 300 143: "Integrated Services Digital Network (ISDN); Audiovisual services; Inbandsignalling procedures for audiovisual terminals using digital channels up to 2 048 kbit/s".[4]ITU-T Recommendation H.320 (1993): "Narrow-band visual telephone systems and terminalequipment".[5]ETS 300 145: "Integrated Services Digital Network (ISDN); Audiovisual services; Videotelephonesystems and terminal equipment operating on one or two 64 kbit/s channels".[6]ITU-T Recommendation H.242 (1993): "System for establishing communication betweenaudiovisual terminals using digital channels up to 2 Mbit/s".[7]ITU-T Recommendation H.221 (1993): "Frame structure for a 64 to 1 920 kbit/s channel inaudiovisual teleservices".SIST EN 300 481 V1.2.2:2003



EN 300 481 V1.2.2 (1997-12)73Definitions, symbols and abbreviations3.1DefinitionsFor the purposes of the present document, the following definitions apply:called end: The Channel Aggregation Unit (CAU) or Multiple Channel Equipment (MCE) which accepts the first64/56 kbit/s channel connection request of the whole session, resulting in the establishment of the "initial channel". Ifduring fault-recovery procedures the initial channel is transferred to another connection, this does not affect thedefinition (see note 1).calling end: The CAU or MCE which requests the first 64/56 kbit/s channel connection of the whole session, resultingin the establishment of the "initial channel". If during fault-recovery procedures the initial channel is transferred toanother connection, this does not affect the definition (see note 1).Channel Aggregation Unit (CAU): A device having both multiple 64 kbit/s accesses and a single access at a higherbitrate. Reference in the present document to "CAU" or "aggregator" means equipment conforming to the presentdocument.compatibility bits: Bit 8 of the first sixteen octets in every time slot of a single channel except time slot 1.external setting: Term used to express operations outside the scope of the present document which determine thebehaviour of a CAU as to choice of option or timing of its action.H.221: See subclause 3.1, H.221 frame structure, H.221 framingH.221 frame structure, H.221 framing: Frame structure according to ITU-T Recommendation H.221 [7], as set out inETS 300 144 [2].H.244 aggregation: Terminal-Aggregator CommunicationH.320 terminal: A terminal that conforms to ITU-T Recommendation H.320 [4] (see note 2).ISO aggregation: No Terminal-Aggregator Communicationmode H2: Modes of aggregation by the method given in clauses 7 and 8 of the present document.modes B1, B2, B3: Modes of aggregation by the method of ISO/IEC 13871 [1], see subclause 4.2.Multiple Channel Equipment (MCE): A terminal or other unit (such as a Local Area Network (LAN) gateway)directly attached to an ISDN (through one or more ISDN accesses, whether basic accesses or primary rate access(es)).No Terminal-Aggregator Communication Case (ISO Aggregation Case): No in-band management communicationbetween Single Channel Equipment (SCE) and CAU takes place - the single channel is only a clear path for the datawhich will be wholly transmitted to the remote party; any communication between the terminal and the CAU is bymeans not specified in the present document (see clause 8).redundant command: A Bit Allocation Signal (BAS) command which repeats, unchanged, a previously transmittedmode value which is still in force.Single Channel Equipment (SCE): A terminal or other unit (such as a LAN interface) having a single serial bi-directional digital interface.H.244 aggregation case: In-band communication between SCE and CAU takes place using ITU-T RecommendationH.221 BAS codes (see clauses 7 and 8 of the present document).user information: The application data streams passing (in both directions) between CAU and SCE (see note 3).NOTE 1:The significance of "calling" and "called" end-points is mentioned in subclause 7.1.3.NOTE 2:ETS 300 145 [5] is the ETSI equivalent to ITU-T Recommendation H. 320 [4]. The scope ofETS 300 145 [5] is, however, restricted to systems supporting 1B or 2B access.SIST EN 300 481 V1.2.2:2003



EN 300 481 V1.2.2 (1997-12)8NOTE 3:In the audiovisual cases, the application data stream includes the ITU-T Recommendation H.221 [7]frame structure.3.2SymbolsFor the purposes of the present document, the following symbols apply:NOTE:For readability, the capability and command values listed in ETS 300 144 [2] are referred to in the presentdocument by their names rather than codepoint byte values; the use of {name} for capabilities and [name]for commands serves to distinguish between these.Nan integer, applied to 64/56 kbit/s channels to define a parallel (un-aggregated) bitstream of rateN×64 kbit/s.nan integer, applied to 64 kbit/s to define a serial (or otherwise aggregated) bitstream of raten*64 kbit/s.Nathe number of active 64/56 kbit/s channels between CAU and MCE or between two CAUs.Nmthe maximum number of 64/56 kbit/s channels which can be accepted by a CAU transmitting thevalue {Nm×B}.N'mused to denote the incoming value of Nm from the remote CAU, or equivalent from an MCE.Ndthe number of connections requested by the calling end, the lower of Nm and N'm.{N×64k}capabilities in the series {1B}, {2B}, {3B}. corresponding to N=1, 2, 3., (applies to Mode H2only).{n*64k}capabilities in the series {64k}, {128k}, {192k}. corresponding to n=1, 2, 3.nmsuch that {nm*64k} is the highest transfer-rate capability incoming from the SCE for which thecontinuous series of rate capabilities {(nm-1)*64k}, {(nm-2)*64k},.{2*64k} is also present inthe capability set (capset).[N×64]Multiple-channel commands (as defined in ETS 300 144 [2]).[n*64k]Single channel commands (as defined in ETS 300 144 [2]).[capex]command issued by a CAU (see subclause 6.3.6.3) to an SCE to stimulate a capability exchange.[AggIN]*a double Single Byte Extension (SBE) symbol indicating the number n as determined by theprocess of subclause 6.3.4.2; see the procedure described in clause 7 (see ETS 300 144 [2]).{null}capability having no significance other than as a filler; only ever transmitted by a CAU, andtherefore it identifies the capset as having last come from, or been forwarded by, a CAU; SCEignores any number of these in an incoming capset (see ETS 300 144 [2]).{SM-comp}capability to transmit and receive user information without using any compatibility bits, settingthese to 1 (see ETS 300 144 [2]).[SM-comp]user information is not contained in the compatibility bits (and is not sent in the compatibility bitsin the reverse direction either). See ETS 300 144 [2]. SAudible signal (to be defined), which would be recognized by a human user as a call progress tone(he would not hang up).3.3AbbreviationsFor the purposes of the present document, the following abbreviations apply:AVAudiovisualBASBit Allocation Signalcapexcapability exchangecapsetCapability setCAUChannel Aggregation UnitFASFrame Alignment SignalISDNIntegrated Services Digital NetworkLANLocal Area NetworkMBEMulti Byte ExtensionMC (side)Multiple Channel (side, of a CAU)MCMultiple ChannelMCEMultiple Channel EquipmentNIINetwork Indicate Incompatible - aggregatorsSBESingle Byte ExtensionSC (side)Single Channel (side, of a CAU)SIST EN 300 481 V1.2.2:2003



EN 300 481 V1.2.2 (1997-12)9SCESingle Channel EquipmentSM-compSingle Multiple compatibilityUDUnspecified Data4General4.1Application of the present documentOn the single channel connections, which may be very short if the terminal and Channel Aggregation Unit (CAU) areco-located, or much longer if a telecommunications link is involved, two options are covered by the present document:a)no in-band management communication on the single channel, this being only a clear path for the data which willbe wholly transmitted to the remote party; any communication between the terminal and the CAU is by means notspecified in the present document; this is referred to as the "ISO Aggregation" case - No Terminal-AggregatorCommunication;b)in-band communication as specified in the present document, using the Bit Allocation Signal (BAS) codesdefined in ETS 300 144 [2] and the procedures of ETS 300 143 [3]; this is referred to as the "H.244Aggregation" case - Terminal­Aggregator Communication. This corresponds to the use of Mode H2 (seesubclause 4.2, figure 8 and associated text).4.1.1Intercommunication of audiovisual equipmentsFor audiovisual terminals conforming to ETS 300 144 [2] and ETS 300 143 [3], the present document provides forsynchronization and aggregation of up to 24 channels of 64/56 kbit/s, each being with or without octet integrity andrelative transmission delay in the range ±1 second.Provision is made for the following intercommunication Cases A to C.4.1.1.1Case AFor interconnection of a Single Channel Equipment (SCE) and a Multiple Channel Equipment (MCE) audiovisual end-point, both conforming to ETS 300 144 [2] and ETS 300 143 [3], only the H.244 Aggregation approach can be followed(see figure 1); this involves only one CAU, which may be within the network or close to the single channel end-point.MCESCECAUISDNH.244AggregationFigure 1: Case A4.1.1.2Case BThis case provides for interconnection between two single channel audiovisual end-points which see the aggregated linkpurely as a clear data channel; each has a CAU associated with it, but there is no in-band control communicationbetween the end-point and its associated CAU (see figure 2); this is the ISO Aggregation approach. The system isexactly the same as for unspecified data applications (see subclause 4.1.2); the CAU-ISDN-CAU combination providesa clear channel at one of the transfer rates specified in ETS 300 144 [2], and, therefore, shall use Mode B1 or B3 (seesubclause 4.2).SIST EN 300 481 V1.2.2:2003



EN 300 481 V1.2.2 (1997-12)10SCECAUISDNSCECAUISOAggregationISOAggregationoptional external communicationFigure 2: Cases B and D4.1.1.3Case CThis provides for the interconnection of two single channel end-points both conforming to ETS 300 144 [2] andETS 300 143 [3] and capable of the operation described in clauses 7 to 8, the H.244 Aggregation approach (seefigure 3); this involves two CAUs, which may be within the network or close to the single­channel end-points.NOTE: H.244 Aggregation cannot be used at one end and ISO Aggregation at the other, see clause 5.SCECAUISDNSCECAUH.244AggregationH.244AggregationFigure 3: Case C4.1.2Intercommunication of non-audiovisual equipments - Case DThe present document provides for synchronization and aggregation of up to 63 channels of 64/56 kbit/s, each beingwith or without octet integrity and relative transmission delay in the range ± one second. It is applicable to a wide rangeof user information transport, including LAN-LAN interconnect, private circuit back-up, and other "unspecified data"applications. No in-band control communication takes place on the single channel side. The equipment sees theaggregated link purely as a clear data channel, and the structure or content of the data streams is of no concern to theaggregating equipment.The ISO Aggregation approach is appropriate (see figure 2); the CAU-ISDN-CAU combination provides a clear channelat one of the transfer rates specified in ISO/IEC 13871 [1] using Mode B1, B2 or B3 (see subclause 4.2).4.2Definition of the modes of transmission on the MultipleChannel (MC) sideThe four modes of transmission are defined below, the accompanying figures being given by way of example for thecase of about 192 kbit/s on the Single Channel (SC) side.Mode B1: the user information occupies an integral number of 64/56 kbit/s channels (usually the N available andaligned channels); only unframed signals are transmitted (see figure 4), alignment of the channels has previously beenSIST EN 300 481 V1.2.2:2003



EN 300 481 V1.2.2 (1997-12)11achieved using a framed mode, and it is assumed that no slip or other network fault has occurred since then. There areno management bits multiplexed into the stream on either Multiple Channel (MC) or SC sides, and the total bitrates areequal; the mode is therefore confined to ISO Aggregation cases, and rate change cannot occur.CAU192 kbit/s64 kbit/s64 kbit/s64 kbit/sFigure 4: Mode B1 - applicable to the ISO Aggregation case onlyAudiovisual signals according to ETS 300 144 [2] can be transmitted, but the ITU-T Recommendation H.221 [7]framing plays no part in the aggregation process, and shall appear at a random position within one of the B-channels asshown in black in figure 5.CAU64 kbit/s64 kbit/s64 kbit/s192 kbit/sFigure 5: Mode B1 - framed audiovisual signal carried as Unspecified Data (UD)Mode B2: signals are transmitted with framing according to ISO/IEC 13871 [1] (depicted as white in figure 6), the userinformation rate being about 1,5 % less than an integral multiple of 64/56 kbit/s due to the overhead of the framestructure. There is no provision for management bits on the SC side, so the use of this mode is confined to theISO Aggregation case.SIST EN 300 481 V1.2.2:2003



EN 300 481 V1.2.2 (1997-12)12CAU(192-3x) kbit/s(64-x) kbit/s(64-x) kbit/s(64-x) kbit/sFigure 6: Mode B2 - applicable to the ISO Aggregation case onlyMode B3: signals are transmitted with framing in all N channels according to ISO/IEC 13871 [1], the user informationrate being an integral multiple (such as N-1) of 64/56 kbit/s; thus there is a management overhead of about 1,5 % andgenerally some unused capacity, as illustrated in figure 7. The exact bit positions occupied by user information aredefined in ISO/IEC 13871 [1].CAU192 kbit/s(64-x)kbit/s(64-x)kbit/s(64-x)kbit/s(3x) kbit/sunusedcapacityFigure 7: Mode B3 - applicable to the ISO Aggregation case onlyMode H2: only ITU-T Recommendation H.221-framed signals are transmitted (framing is shown as white in figure 8),the user information rate being an integral number of 64/56 kbit/s channels (usually the N available and alignedchannels), including the Frame Alignment Signal (FAS) and BAS within this rate. On the MC side all channels areframed; on the SC side only the I-channel (Time-Slot 1) carries H.221 framing, but the corresponding bits (shown withdashed outline) in the other time-slots shall be vacated, so that framing can be inserted at the CAU in the SC to MCdirection (and removed in the other): this is done under the Single Multiple compatibility ([SM-comp]) command.SIST EN 300 481 V1.2.2:2003



EN 300 481 V1.2.2 (1997-12)13CAU64 kbit/s64 kbit/s64 kbit/s192 kbit/sFigure 8: Mode H2 - applicable to the H.244 Aggregation case onlyMode propertiesThe properties of the four modes are summarized in table 1. "Dynamic rate change" refers to dynamic variation of thenumber N of aggregated channels during a session: rate changes within available connection capacity can normally bemade in less than 40 ms for Modes H2 and B3; when new connections need to be added, the response depends on callset-up time; for Mode B1, interruption of the application is inevitable.Table 1: Mode propertiesMode B1Mode H2Mode B2Mode B3Aggregation overheadNone2,5 % in the additionalchannels1,5 %64/56 kbit/sDynamic rate changesNoYesYesYesExact multiples of64/56 kbit/sYesYes (H.221 - framed only)NoYesInterworking with MCE(audiovisual)NoYesnot applicableNoThe applicability of the Modes is summarized in table 2.Table 2: Mode applicabilityModeAV/non-AVMode applicable when.B1Audiovisualthe remote end is not an MCE, and the remote CAU does not support Mode H2, andMode B3 is considered too inefficient or is not available; bitstream treated as UDonly; ISO Aggregation case, so external means shall be used to set bitrate.Non-audiovisualexact multiple of 64/56 kbit/s required, absence of dynamic rate change tolerable,B3 considered too inefficient.B2Audiovisualnot applicable - B2 does not provide suitable bitrates.Non-audiovisualexact multiple of 64/56 kbit/s not essential, dynamic rate change desired.B3Audiovisualthe remote end is not an MCE, and the remote CAU does not support Mode H2;dynamic rate change more important than efficiency; bitstream treated as UD only;ISO Aggregation case, so external means shall be used to set bitrate.Non-audiovisualexact multiple of 64/56 kbit/s required, dynamic rate change more important thanefficiency.H2Audiovisualremote end is an MCE, or a CAU supporting Mode H2; H.244 Aggregati
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