SIST ETS 300 742 E1:2003

• Abstract:

  To define the physical layer user network interface for a bit rate of 2 Mbit/s (ATM_) to be applied at reference point Sb and Tb.

• Status: Published
• Publication Date: 30-Nov-2003
• ICS: 33.040.20 - Transmission systems
• Technical Committee: SS EIT - Technical Board for the electrotechnical, information technology and telecommunications fields
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Dec-2003
• Due Date: 01-Dec-2003
• Completion Date: 01-Dec-2003
• Ref Project: ETSI ETS 300 742 ed.1 (1997-04) - Transmission and Multiplexing (TM); Physical layer User Network Interface (UNI) for 2 048 kbit/s Asynchronous Transfer Mode (ATM) signals

SIST ETS 300 742 E1:2003 is the Slovenian publication of ETS 300 742 Edition 1 from ETSI. It specifies the physical layer user network interface (UNI) for 2 048 kbit/s Asynchronous Transfer Mode (ATM) signals at the SB and TB reference points of the Broadband Integrated Services Digital Network (B-ISDN) UNI. In practice, it tells equipment designers, network engineers, and test labs how the 2 Mbit/s B-ISDN access interface is carried, powered, framed, and monitored.

What does SIST ETS 300 742 E1:2003 specify?

SIST ETS 300 742 E1:2003 specifies the physical layer interface for B-ISDN access at the SB and TB reference points, with particular attention to electrical transmission over customer wiring. It also covers the transmission system and the Operation Administration and Maintenance (OAM) functions that support the interface.

The document is organized into 10 clauses, followed by an informative bibliography.

Annex	What it covers
Annex A	Bibliography

The main clauses cover scope, normative references, definitions and abbreviations, reference configurations, UNI specifications, service and layering aspects, physical medium characteristics, power feeding, transmission convergence sublayer functions, and UNI related OAM and operational functions.

What are the key requirements of SIST ETS 300 742 E1:2003?

Interface structure and access points

Clause 4 defines the B-ISDN reference configurations and the functional groups B-NT1, B-NT2, B-TE1, B-TE2, and B-TA. This matters because the interface can appear in different customer arrangements, including centralized, distributed, and multipoint configurations.

Clause 5 places the interface points Ia and Ib between the socket and plug of the equipment connection. For implementation, this fixes where the standardized interface ends and the cabling or equipment connector begins.

Physical transmission at 2 048 kbit/s

Clause 7 sets the interface bit rate at 2 048 kbit/s and requires symmetry in both directions. The nominal free-running clock tolerance is 50 parts per million (ppm), so timing design and test equipment must stay within that limit.

The standard recommends electrical interfaces only. It uses two coaxial cables or two twisted pairs, one per direction, with point-to-point wiring and impedances of 75 W or 120 W. It also specifies HDB-3 line coding and references ETS 300 166 for the detailed electrical characteristics. In practice, installers and equipment builders need to match the cabling, termination, and connector style to the selected medium.

Jitter requirements are tied to ITU-T Recommendation G.823. That means compliance is not just about bit rate and wiring, but also about signal quality and clock behavior.

ATM transport, cell handling, and framing

Clause 6 says the physical layer provides transparent transport of ATM cells to the ATM layer and uses a single Physical layer Service Access Point (Ph-SAP). It also splits the physical layer into Physical Medium (PM) and Transmission Convergence (TC) sublayers. For readers, this means the standard is about carrying cells reliably, not about addressing or higher-layer routing.

Clause 9 maps the ATM cell stream into a Plesiochronous Digital Hierarchy (PDH) frame. Time slot 0 is reserved for OAM, time slot 16 is not used, and the remaining time slots carry ATM cells. The Header Error Control (HEC) covers the full cell header and supports both single-bit correction and multi-bit detection, which is important for receiver design and interoperability.

Cell delineation uses the HUNT, PRESYNC, and SYNC states, and scrambling uses the self-synchronizing polynomial x43 + 1. In practice, this is the receiver logic that finds cell boundaries and keeps the stream robust.

Power feeding and operational behavior

Clause 8 makes power feeding to B-NT1 via the UNI optional, but if used it must be on a separate wire pair. The feeding voltage range is -20 V to -57 V relative to ground, and the source must be protected against short circuit and overload. This matters when a provider expects line-powered customer termination equipment.

Clause 10 defines fault reporting using CRC-4, Alarm Indication Signal (AIS), Remote Alarm Indication (RAI), Loss Of Signal (LOS), Loss Of Frame (LOF), and Loss of Cell Delineation (LCD). It also gives state tables for the user side and network side, so implementations can exchange consistent alarm and recovery indications.

What terms does SIST ETS 300 742 E1:2003 define?

• Asynchronous Transfer Mode (ATM) - The cell-based transfer method carried by the interface.
• Broadband Network Termination 1 (B-NT1) - The network termination function at the line side, including line termination and OAM functions.
• Broadband Network Termination 2 (B-NT2) - The higher-function termination that can handle adaptation, multiplexing, buffering, and cell delineation.
• Broadband Terminal Equipment 1 (B-TE1) - Terminal equipment with an interface that complies with the B-ISDN SB and/or TB recommendations.
• Broadband Terminal Adapter (B-TA) - A function that lets TE2 or B-TE2 equipment be served by a B-ISDN UNI.
• Header Error Control (HEC) - The 8-bit protection field used for header correction and detection.
• Operation Administration and Maintenance (OAM) - The fault, alarm, and monitoring functions used to supervise the UNI.

Who uses SIST ETS 300 742 E1:2003?

This standard is used by B-ISDN equipment designers, access network engineers, terminal manufacturers, and test laboratories. It is also relevant to installers and quality managers who need to select cabling, connectors, timing, alarm handling, and interoperability tests for 2 048 kbit/s ATM access equipment.

Which standards are used with SIST ETS 300 742 E1:2003?

• ITU-T I.113 - Provides the vocabulary for B-ISDN terms.
• ITU-T I.321 - Defines the PM and TC sublayer functions.
• ITU-T I.361 - Defines the ATM layer and ATM cell concepts.
• ITU-T I.413 - Gives the B-ISDN user-network interface reference model.
• ITU-T I.432.1 / I.432.3 - Provide the physical layer framework, including the 2 048 kbit/s case.
• ETS 300 166 - Provides the 2 048 kbit/s electrical interface characteristics and HDB-3 coding basis.
• ITU-T G.804 - Defines ATM cell mapping into PDH.
• ITU-T G.823 - Sets jitter and wander control limits.
• ITU-T G.704 / G.706 / G.732 / G.775 - Cover frame structure, CRC-4, PCM characteristics, and LOS/AIS criteria.
• ITU-T I.610 - Provides B-ISDN OAM principles and functions.
• IEC 950 - Supports the safety approach for the feeding interface.

What does the SIST ETS 300 742 E1:2003 document contain?

The document includes reference configuration drawings for B-ISDN access, examples of physical realizations, and interface-location figures for SB and TB. It also contains frame structure tables, CRC-4 multiframe information, and the idle-cell header pattern used by receivers.

Later clauses provide HEC receiver state diagrams, cell delineation procedures, scrambling behavior, and detailed fault/state tables for the user and network sides. These parts are the practical basis for design verification, receiver implementation, conformance testing, and maintenance behavior.

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.70Transmission and Multiplexing (TM); Physical layer User Network Interface (UNI) for 2 048 kbit/s Asynchronous Transfer Mode (ATM) signals33.040.20Prenosni sistemTransmission systemsICS:Ta slovenski standard je istoveten z:ETS 300 742 Edition 1SIST ETS 300 742 E1:2003en01-december-2003SIST ETS 300 742 E1:2003SLOVENSKI
STANDARD
EUROPEANETS 300 742TELECOMMUNICATIONApril 1997STANDARDSource: ETSI TC-TMReference: DE/TM-03064ICS:33.020Key words:Broadband, ISDN, access, interface, UNI, ATMTransmission and Multiplexing (TM);Physical layer User Network Interface (UNI)for 2 048 kbit/s Asynchronous Transfer Mode (ATM) signalsETSIEuropean Telecommunications Standards InstituteETSI SecretariatPostal address: F-06921 Sophia Antipolis CEDEX - FRANCEOffice address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCEX.400: c=fr, a=atlas, p=etsi, s=secretariat - Internet: [e-mail].: [phone] - Fax: [phone]Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and theforegoing restriction extend to reproduction in all media.© European Telecommunications Standards Institute 1997. All rights reserved.SIST ETS 300 742 E1:2003

Page 2ETS 300 742: April 1997Whilst every care has been taken in the preparation and publication of this document, errors in content,typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to"ETSI Editing and Committee Support Dept." at the address shown on the title page.SIST ETS 300 742 E1:2003

Page 3ETS 300 742: April 1997ContentsForeword.51Scope.72Normative references.73Definitions and abbreviations.83.1Definitions.83.2Abbreviations.84Reference configuration at the user-network interface.94.1Functional groups and reference points.94.2Examples of physical realizations.104.3Basic characteristics of the interfaces at TB and SB reference points for 2 048 kbit/s.144.3.1Interface at TB reference point.144.3.2Interface at the SB reference point.144.3.3Relationship between interfaces at SB and TB.144.4Relationship between ISDN interfaces.144.5Functional groups characteristics.144.5.1Network termination 1 for B-ISDN (B-NT1).144.5.2Network termination 2 for B-ISDN (B-NT2).144.5.3Terminal equipment for B-ISDN (B-TE).154.5.3.1Terminal equipment type 1 for B-ISDN (B-TE1).154.5.3.2Terminal equipment type 2 for B-ISDN (B-TE2).154.5.4Terminal adapter for B-ISDN (B-TA).155UNI specifications.155.1Interface location with respect to reference configuration.155.2Interface location with respect to the wiring configuration.156Service and layering aspects of the physical layer.166.1Services provided to the ATM-layer.166.2Service primitives exchanged with the ATM layer.166.3Sublayering of the physical layer.167Physical medium characteristics at the TB and SB reference point of the UNI for 2 048 kbit/s.167.1Bit rate and interface symmetry.167.2Physical characteristics.177.2.1Electrical interface.177.2.1.1Interface range.177.2.1.2Transmission medium.177.2.1.3Electrical parameters at interface points Ia and Ib.177.2.1.4Electrical connectors.177.2.1.5Line coding.187.2.1.6Electromagnetic compatibility and electromagneticinterference requirements.187.2.1.7Jitter and Wander.188Power feeding.188.1Provision of power.188.2Power available at B-NT1.188.3Feeding voltage.188.4Safety requirements.199Functions provided by the transmission convergence sublayer.199.1Transfer capability for 2 048 kbit/s.19SIST ETS 300 742 E1:2003

Page 4ETS 300 742: April 19979.2Physical Layer aspects.199.2.1Timing.199.2.2Interface structure for 2 048 kbit/s.199.3Header error control.219.3.1Header error control functions.219.3.2Header error control sequence generation.239.4Idle cells.239.5Cell delineation and scrambling.239.5.1Cell delineation and scrambling objectives.239.5.2Cell delineation algorithm.249.5.3Cell delineation performance.259.5.4Scrambler operation.2510UNI related OAM and operational functions.2510.1Operational functions.2510.1.1Definition of signals.2510.1.2Definitions of state tables at network and user sides.2710.1.2.1Layer 1 states on the user side of the interface.2710.1.2.2Layer 1 states at the network side of the interface.2810.1.2.3Definition of primitives.2910.1.2.4State tables.30Annex A (informative):Bibliography.35History.36SIST ETS 300 742 E1:2003

Page 5ETS 300 742: April 1997ForewordThis European Telecommunication Standard (ETS) defines the user network access physical layerinterface to be applied to the TB, SB reference points of the reference configurations of the B-ISDN UserNetwork Interface (UNI) for Broadband Integrated Services Digital Network (B-ISDN) applications. Itaddresses the structure of the transmission system that is used at these interfaces as well as theimplementation of the UNI related Operation Administration and Maintenance (OAM) functions at thephysical layer.This ETS has been produced by the Transmission and Multiplexing Technical Committee of the EuropeanTelecommunications Standards Institute (ETSI) taking into account the recommendations given in ITU-TRecommendations I.413 [7] and I.432 [8].Transposition datesDate of adoption:4 April 1997Date of latest announcement of this ETS (doa):31 July 1997Date of latest publication of new National Standardor endorsement of this ETS (dop/e):31 January 1998Date of withdrawal of any conflicting National Standard (dow):31 January 1998SIST ETS 300 742 E1:2003

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Page 7ETS 300 742: April 19971ScopeThis European Telecommunication Standard (ETS) defines the physical layer interface to be applied tothe SB and TB reference points of the reference configurations of the Broadband Integrated ServicesDigital Network (B-ISDN) User Network Interface (UNI) at 2 048 kbit/s. It addresses separately thephysical media and the transmission system used at these interfaces and addresses also theimplementation of UNI related Operation Administration and Maintenance (OAM) functions.The physical medium for the interfaces at the SB and TB reference points should take into account thatonly electrical wires are to be used to cable customer equipment.This ETS mainly is based on ETS 300 300 [13], being responsible for the bit rates 155 520 kbit/s and622 080 kbit/s and the ITU-T Recommendation I.432 [8] being responsible for the bit rates 622 080 kbit/s,155 520 kbit/s, 2 048 kbit/s and 1 544 kbit/s.2Normative referencesThis ETS incorporates by dated or undated reference, provisions from other publications. Thesenormative references are cited at the appropriate places in the text and the publications are listedhereafter. For dated references, subsequent amendments to or revisions of any of these publicationsapply to this ETS only when incorporated in it by amendment or revision. For undated references the latestedition of the publication referred to applies.[1]ITU-T Recommendation G.804: "ATM cell mapping into Plesiochronous DigitalHierarchy (PDH)".[2]ETS 300 166 (1993): "Transmission and Multiplexing (TM); Physical andelectrical characteristics of hierarchical digital interfaces for equipment using the2048 kbit/s - based plesiochronous or synchronous digital hierarchies".[3]ITU-T Recommendation I.431: "Primary rate user-network interface - Layer 1specification".[4]ITU-T Recommendation G.823 (1993): "The control of jitter and wander withindigital networks which are based on the 2 048 kbit/s hierarchy".[5]ITU-T Recommendation I.113 (1993): "Vocabulary of terms for broadbandaspects of ISDN".[6]ITU-T Recommendation I.361 (1993): "B-ISDN ATM Layer specification".[7]ITU-T Recommendation I.413 (1993): "B-ISDN user-network interface".[8]ITU-T Recommendation I.432.1 (1995): "B-ISDN user-network interface -Physical Layer specification, General Characteristics".ITU-T Recommendation I.432.3 (1995): "B-ISDN user-network interface -Physical Layer specification for 2 048 kbit/s".[9]ITU-T Recommendation I.610 (1993): "B-ISDN operation and maintenanceprinciples and functions".[10]ITU-T Recommendation X.200: "Information technology - Open SystemsInterconnection - Basic reference model: The basic model".[11]IEC 950: "Safety of information technology equipment, including electricalbusiness equipment".[12]ITU-T Recommendation I.321 (1991): "B-ISDN protocol reference model and itsapplication".SIST ETS 300 742 E1:2003

Page 8ETS 300 742: April 1997[13]ETS 300 300 (1997): "Broadband Integrated Services Digital Network (B-ISDN);Synchronous Digital Hierarchy (SDH) based user network access; Physical layerUser Network Interfaces (UNI) for 155 520 kbit/s and 622 080 kbit/sAsynchronous Transfer Mode (ATM) B-ISDN applications".[14]ITU-T Recommendation I.604: "Application of maintenance principles to ISDNprimary rate access".[15]ITU-T Recommendation G.706: "Frame alignment and cyclic redundancy check(CRC) procedures relating to basic frame structures definedin Recommendation G.704".[16]ITU-T Recommendation G.704: "Synchronous frame structures at primary andsecondary hierarchical levels".[17]ITU-T Recommendation G.732: "Characteristics of primary PCM multiplexequipment operating at 2 048 kbit/s".[18]ITU-T Recommendation G.775: "Loss of signal (LOS) and alarm indicationsignal (AIS) defect detection and clearance criteria".3Definitions and abbreviations3.1DefinitionsFor the purposes of this ETS, the definitions given in ITU-T Recommendation I.113 [5] apply, specially foridle cell, valid cell and invalid cell.to be defined: These items or values are not yet specified.for further study: These items are required for further study.3.2AbbreviationsFor the purposes of this ETS, the following abbreviations apply:AISAlarm Indication SignalATMAsynchronous Transfer ModeB-ISDNBroadband Integrated Services Digital NetworkB-NTBroadband Network TerminationB-TABroadband Terminal AdapterB-TEBroadband Terminal EquipmentB–UNIBroadband–User Network InterfaceBERBit Error RateCATVCAble TeleVisionCLPCell Loss PriorityCMICoded Mark InversionCRCCyclic Redundancy CheckEMCElectro-Magnetic CompatibilityEMIElectro-Magnetic InterferenceFAWFrame Alignment WordHECHeader Error ControlISDNIntegrated Services Digital NetworkLANLocal Area NetworkLCDLoss of Cell DelineationLOFLoss Of FrameLOSLoss Of SignalLSBLeast Significant BitMAMedium AdapterMPHManagement Physical HeaderMSBMost Significant BitSIST ETS 300 742 E1:2003

Page 9ETS 300 742: April 1997NRZNon Return to ZeroOAMOperation Administration and MaintenanceOCDOut of Cell DelineationOSIOpen Systems InterconnectionPDHPlesiochronous Digital Hierarchyppmparts per millionPHPhysical HeaderPMPhysical MediumRAIRemote Alarm IndicationRDIRemote Defect IndicationREIRemote Error IndicationSDHSynchronous Digital HierarchySMFSub Multi FrameSTISurface Transfer ImpedanceTCTransmission ConvergenceTFVTerminal Failure VoltageTSTime SlotUNIUser Network InterfaceVCVirtual ContainerVPVirtual Path4Reference configuration at the user-network interface4.1Functional groups and reference pointsThe reference configurations defined for ISDN basic access and primary access are considered generalenough to be applicable to all aspects of the B-ISDN accesses.Figure 1 shows the B-ISDN reference configurations which contain the following:-functional groups: B-NT1; B-NT2; B-TE1; TE2; B-TE2; and B-TA;-reference points: TB; SB and R.B-TE1B-NT1B-TAReference pointSBRSBFunctional groupB-TA
Broadband Terminal AdaptorB-TE
Broadband Terminal EquipmentB-NT
Broadband Network TerminationB-NT2TBTE2orB-TE2Figure 1: B-ISDN reference configurationsIn order to clearly illustrate the broadband aspects, the notation for reference points and for functionalgroups with broadband capabilities are appended with the letter B (e.g. B-NT1, TB). The broadbandfunctional groups are equivalent to the functional groups defined in ISDN. Interfaces at the R referencepoint may or may not have broadband capabilities.Interfaces at reference points SB and TB will be standardized. These interfaces will support all ISDNservices.SIST ETS 300 742 E1:2003

Page 10ETS 300 742: April 19974.2Examples of physical realizationsFigure 2 gives examples of physical configurations illustrating combinations of physical interfaces atvarious reference points. The examples cover configurations that could be supported by standardizedinterfaces at reference points SB and TB. Other configurations may also exist. For example, physicalconfigurations of B-NT2 may be distributed or use shared medium to support Local Area Network (LAN)emulation and other applications.Figure 3 illustrates possible physical configurations, but does not preclude alternative configurations.Whether a single interface at the SB reference point can cover different configurations, as illustrated infigure 3, is for further study.Figures 2a and 2b show separate interfaces at the SB and TB reference points; figures 2c) and 2d) showan interface at SB but not at TB; figures 2e and 2f show an interface at TB but not at SB; figures 2g and 2hshow separate interfaces at S, SB and TB; figures 2i and 2j show interfaces at SB and TB which arecoincident.SIST ETS 300 742 E1:2003

Page 11ETS 300 742: April 1997Additionally, figures 2b), 2d), 2f), 2h) and 2j) show an interface at reference point R.B-NT2TSB-NT1BBa)B-TE1B-NT2TSB-NT1BBB-TARb) TE2
orB-TE2 Configurations where B-ISDN physical interfaces occur at reference points SB and TBSBc)B-NT1B-NT2+B-TE1SBB-TARd)B-NT1B-NT2+TE2
orB-TE2 NOTE Configurations where B-ISDN physical interfaces occur at reference point SB onlyB-NT2B-NT1+e)B-TETBTB-NT1BB-TARB-NT2+f)TE2
orB-TE2 Configurations where B-ISDN physical interfaces occur at reference point TB onlyB-NT2TSB-NT1BSBRh)TATE2B-TE1B-NT2TSB-NT1BTE1g)B-TE1SBConfigurations where B-ISDN and ISDN physical interfaces occur at reference points S, SB and TBB-NT1RB-TAj)TE2
orB-TE2 S
and T
coincidentBBB-NT1B-TE1i)S
and T
coincidentBBConfigurations where a single B-ISDN physical interface occurs at a location where both referencepoints SB and TB coincideEquipment implementingfunctional groupsPhysical interface at thedesignated reference pointNOTE:The need for an access to a TB-Reference point (between B-NT1 and B-NT2) is for furtherstudy.Figure 2: Examples of physical configurations for broadband user applicationsSIST ETS 300 742 E1:2003

Page 12ETS 300 742: April 1997a) centralized B-NT2 configurationB - TE1B - TE1B - TE1B - NT2B - NT1TBSBSBSBb) distributed B-NT2 configurationsb1)generic configurationWWMAMAWMA(note 1)SBSBRTE2orB - TE2B - TAB - NT1B - NT2MAB - TARTE2orB - TE2B - TE1(note 2)TBb2)physical configurationsMAB - TE1B - NT1WWTBTBMAMAB - TE1SBSBB - NT1B - TE1SBWWWWB - TE1B - TE1SBSB(note 1)MAMAMAMASIST ETS 300 742 E1:2003

Page 13ETS 300 742: April 1997c) multi-access B-TE configurationsc1)generic configurations (note 7)TBB - NT1B - NT2SBB - TE*B - TE*B - TE*SSBSSB(note 3)c2)physical configurations(note 5)(note 4)(note 6)B - NT2B - NT1SSBSSBSBTBB - TE*B - TE*B - TE*SBB - NT2B - NT1SSBSSBSBTBB - TE*B - TE*B - TE*(note 5)(note 4)SSBSSBSSBSSBSSBSSBSBSBSBB - NT2B - NT1TBB - TE*B - TE*B - TE*B - TE*B - TE*B - TE*B - TE*B - TE*B - TE*NOTE 1:MA: Medium Adapter; accommodates the specific topology of the distributed B-NT2. Theinterface at W may include topology dependant elements; it may be a non-standardizedinterface.NOTE 2:There will be a physical link between these two Medium Adapters in the case of ringconfigurations.NOTE 3:There will be a physical link between B-TE* and B-NT2 in the case of ring configurations.NOTE 4:B-TE* includes shared medium access functions.NOTE 5:The measurable physical characteristics of the SSB interface are identical to those of the SBinterface. The functional characteristics of the interface, however, may be a superset of thoseat the SB interface.NOTE 6:The B-NT2 may be null in the case of commonalty between SB and TB.NOTE 7:Additional termination functions (e.g. for loopback in bus configuration) and OAM functions maybe necessary for multi-access B-TE* configurations. Requirements and implementations ofthese functions are for further study.Figure 3: Examples of physical configurations for multipoint applicationsSIST ETS 300 742 E1:2003

Page 14ETS 300 742: April 19974.3Basic characteristics of the interfaces at TB and SB reference points for 2 048 kbit/s4.3.1Interface at TB reference pointThere is only one interface per B-NT1 at the TB reference point. The operation of the physical medium ispoint-to-point in the sense that there is only one sink (receiver) in front of one source (transmitter).Point-to-multipoint configurations at TB at the ATM and higher layers are for further study.4.3.2Interface at the SB reference pointOne or more SB interfaces per B-NT2 are present. The interface at the SB reference point is point-to-pointat the physical layer in the sense that there is only one sink (receiver) in front of one source (transmitter)and may be point to multipoint at the other layers.4.3.3Relationship between interfaces at SB and TBConfigurations described in figures 2i and 2j require that the interface specifications at TB and SB shouldhave a high degree of commonalty, in order to ensure that a simple broadband terminal may beconnected directly to the TB interface.4.4Relationship between ISDN interfacesFigures 2g and 2h show configurations where B-ISDN and ISDN interfaces may occur at SB and Srespectively. In this case B-NT2 functionalities have to ensure the interface capabilities for both S and SB.Other configurations for supporting terminals at the interface at the S reference point may exist.4.5Functional groups characteristicsLists of functions for each functional group are given below. Each particular function is not necessarilyrestricted to a single functional group. For example, "interface termination" functions are included in thefunction lists of B-NT1, B-NT2 and B-TE. The function lists for B-NT1, B-NT2, B-TE and B-TA are notexhaustive. Not all specific functions in a functional group need to be present in all implementations.4.5.1Network termination 1 for B-ISDN (B-NT1)This functional group includes functions broadly equivalent to layer 1 of the OSI reference model.Examples of B-NT1 functions are:-line transmission termination;-transmission interface handling;-OAM functions.4.5.2Network termination 2 for B-ISDN (B-NT2)This functional group includes functions broadly equivalent to layer 1 and higher layers of the ITU-TRecommendation X.200 [10] reference model. B-NT2 can be null in the case of commonalty between TBand SB.Examples of B-NT2 functions are:-adaptation functions for different media and topologies (MA functions);-functions of a distributed B-NT2;-cell delineation;-concentration;-buffering;-multiplexing/demultiplexing;-resource allocation;-usage parameter control;-adaptation layer functions for signalling (for internal traffic);-interface handling (for the TB and SB interfaces);SIST ETS 300 742 E1:2003

Page 15ETS 300 742: April 1997-OAM functions;-signalling protocol handling;-switching of internal connections.B-NT2 implementations may be concentrated or distributed. In a specific access arrangement, the B-NT2may consist only of physical connections. When present, implementations of the B-NT2 are locallypowered.4.5.3Terminal equipment for B-ISDN (B-TE)This functional group includes functions broadly belonging to layer 1 and higher layers of the ITU-TRecommendation X.200 [10] reference model.Examples of B-TE functions are:-user/user and user/machine dialogue and protocol;-interface termination and other layer 1 functions;-protocol handling for signalling;-connection handling to other equipment;-OAM functions.The possibility of powering the B-TE via the SB interface is for further study.4.5.3.1Terminal equipment type 1 for B-ISDN (B-TE1)This functional group includes functions belonging to the B-TE functional group with an interface thatcomplies with the B-ISDN SB and/or TB interface recommendations.4.5.3.2Terminal equipment type 2 for B-ISDN (B-TE2)This functional group includes functions belonging to the functional group B-TE but with a broadbandinterface that complies with interface ITU-T Recommendations other than the B-ISDN interface ITU-TRecommendations or interfaces not included in ITU-T Recommendations.4.5.4Terminal adapter for B-ISDN (B-TA)This functional group includes functions broadly belonging to layer 1 and higher layers of the ITU-TRecommendation X.200 [10] reference model that allow a TE2 or a B-TE2 terminal to be served by aB-ISDN UNI.5UNI specifications5.1Interface location with respect to reference configurationAn interface point Ia is adjacent to the B-TE or the B-NT2 on their network side; interface point Ib isadjacent to the B-NT2 and to the B-NT1 on their user sides (see figure 4).B-TEB-NT2B-NT1BSTBIabIIabIFigure 4: Reference configuration at reference points SB and TB5.2Interface location with respect to the wiring configurationThe interface points are located between the socket and the plug of the connector attached to the B-TE,B-NT2 or B-NT1. The location of the interface point is shown in figure 5.SIST ETS 300 742 E1:2003

Page 16ETS 300 742: April 1997In this ETS, the term "B-NT" is used to indicate network terminating layer 1 aspects of B-NT1 and B-NT2functional groups, and the term "TE" is used to indicate terminal terminating layer 1 aspects of B-TE1,B-TA and B-NT2 functional groups, unless otherwise indicated.connecting cordWiring at thecustomer premisesB - TEB - NTIabI(note)NOTE:The length of the connecting cord can be zero.Figure 5: Wiring configuration6Service and layering aspects of the physical layer6.1Services provided to the ATM-layerThe physical layer provides for the transparent transmission of ATM-PDUs between physical layer ServiceAccess Points (Ph-SAP). The ATM-PDU is called ATM cell. The ATM cell is defined in ITU-TRecommendation I.361 [6]. As no addressing is implemented in the physical layer only a single Ph-SAPcan exists at the boundary between physical layer and ATM layer. The inter-arrival time between cellspassed to the ATM layer is not defined (asynchronous transmission). The physical layer provides the ATMlayer with timing information.6.2Service primitives exchanged with the ATM layerThe service primitives between physical layer and ATM-layer are defined in ITU-TRecommendation I.361, section 3.2 [6].6.3Sublayering of the physical layerThe physical layer is subdivided into two sublayers:-the physical medium (PM) sublayer;-the transmission convergence (TC) sublayer.No service access point and service primitives are defined between the PM and the TC sublayers. Thefunctions of the individual sublayer are defined in ITU-T Recommendation I.321 [12].7Physical medium characteristics at the TB and SB reference point of the UNIfor 2 048 kbit/s7.1Bit rate and interface symmetryThe bit rate of the interface is 2 048 kbit/s. The interface is symmetric, i.e. it has the same bit rate in bothtransmission directions.The nominal bit rate in free running clock mode shall be 2 048 kbit/s with a tolerance of 50 parts permillion (ppm).SIST ETS 300 742 E1:2003

Page 17ETS 300 742: April 19977.2Physical characteristicsOnly electrical interfaces are recommended. The implementation selected depends on the distance to becovered and user requirements arising from the details of the installation.7.2.1Electrical interface7.2.1.1Interface rangeThe maximum range of the interface depends on the specific attenuation of the transmission mediumused (e.g. twisted pair, coaxial cable) and is for further study.7.2.1.2Transmission mediumTwo coaxial cables or two twisted pairs, one for each direction, shall be used. The wiring configurationshall be point-to-point.The impedance shall be respectively 75 W and 120 W. Further details (e.g. attenuation of the electricalpath between the interface points Ia and Ib) shall match the definitions according to ETS 300 166 [2].7.2.1.3Electrical parameters at interface points Ia and IbThe digital signal presented at the output port and the port impedance should conform to ETS 300 166 [2]for the interface at 2 048 Mbit/s.The digital signal presented at the input port and the port impedance should conform to ETS 300 166 [2]for the interface at 2 048 Mbit/s modified by the characteristics of the interconnecting coaxial pair ortwisted pair.7.2.1.4Electrical connectorsThe presentation of interface point Ib at B-NT1 or B-NT2 shall be via a socket.The presentation of interface point Ia at B-TE or B-NT2 shall be using either:a)a socket, i.e. the connection shall be made to the equipment toward the network with a cable withplugs on both ends; orb)an integral connecting cord with plug on the free end (see figure 6: Connector types).socketsocketplugPresentation of interface point 1b at B-NT1 and B-NT2Presentation of interface point 1a at B-TE and B-NT2Figure 6: Connector typesSIST ETS 300 742 E1:2003

Page 18ETS 300 742: April 19977.2.1.5Line codingThe line coding shall be HDB-3; see ETS 300 166 [2].7.2.1.6Electromagnetic compatibility and electromagnetic interference requirementsThe specification of respective values for EMC are for further study.7.2.1.7Jitter and WanderFor the electrical B-UNI, the interface output Jitter shall be in accordance with the appropriate limits givenin ITU-T Recommendation G.823 [4].Equipment having an electrical B-UNI (e.g. B-NT1, B-NT2, B-TE) and which meets the input Jittertolerance and the Jitter transfer specifications given in ITU-T Recommendation G.823 [4], is assured ofproper operation when the interface output Jitter conforms to the limits in ITU-TRecommendation G.823 [4].Values and measurements for Terminal Failure Voltage (TFV) are for further study.8Power feeding8.1Provision of powerThe provision of power to the B-NT1 via the UNI is optional. If the power is provided via the UNI, thefollowing conditions shall
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