ETSI ETR 343 TECHNICAL March 1997 REPORT

Transcription

1 ETSI ETR 343 TECHNICAL March 1997 REPORT Surce: ETSI TC-TE Reference: DTR/TE ICS: Key wrds: ISDN, lwer layer, prtcl, satellite, terminal Integrated Services Digital Netwrk (ISDN); Extended lwer layer prtcls; Definitin f B and D Channel prtcls with prpsed Requirements List (RL) and prfile specific Implementatin Cnfrmance Statement (ICS) ETSI Eurpean Telecmmunicatins Standards Institute ETSI Secretariat Pstal address: F Sphia Antiplis CEDEX - FRANCE Office address: 650 Rute des Luciles - Sphia Antiplis - Valbnne - FRANCE X.400: c=fr, a=atlas, p=etsi, s=secretariat - Internet: secretariat@etsi.fr Tel.: Fax: Cpyright Ntificatin: N part may be reprduced except as authrized by written permissin. The cpyright and the freging restrictin extend t reprductin in all media. Eurpean Telecmmunicatins Standards Institute All rights reserved.

2 Page 2 Whilst every care has been taken in the preparatin and publicatin f this dcument, errrs in cntent, typgraphical r therwise, may ccur. If yu have cmments cncerning its accuracy, please write t "ETSI Editing and Cmmittee Supprt Dept." at the address shwn n the title page.

3 Page 3 Cntents Frewrd...9 Intrductin Scpe References Definitins and abbreviatins Definitins Abbreviatins Cnfrmance requirements Prtcl stack Supprted prtcls Relatinship between prtcls Physical interface (layer 1) Link layer (layer 2): D-channel Link layer (layer 2): B-channel Prtcl t be used Octet alignment Idle channel state Active channel state - called terminal Active channel state - calling terminal Recgnitin f ctet alignment Return t idle channel state Terminal type selectin General Prcedure at calling terminal Prcedure at called terminal Selectin by calling terminal Negtiatin f essential data link parameters During terminal type selectin On receipt f XID frame with FIS = Cntent and frmat f the XID frame Frmat Identifier Subfield (FIS) Data Link Subfield (DLS) User Data Subfield (UDS) Data link prcedures Mde f transmissin Mde f peratin Frame reject respnse Single link prcedure Prcedure fr addressing Link set-up Discnnected phase Receiving an I-frame Unslicited UA in infrmatin transfer phase Prcedure fr link resetting Timer T Parameter T Timer T Maximum number f transmissins N Maximum frame length N Maximum number f utstanding I-frames k...24

4 Page Netwrk layer (layer 3): D-channel Prtcl t be used Terminal selectin Cmpatibility infrmatin prvided by the calling terminal BC infrmatin element Lw layer cmpatibility infrmatin element HLC infrmatin element Cmpatibility checking by the called terminal Lw layer cmpatibility negtiatin between users Call acceptance cnditins Interwrking with ther netwrks Interwrking with nn-isdns Outging calls Incming calls Interwrking with private telecmmunicatin netwrks Interwrking with a netwrk having restricted bearer capability Use f ISDN supplementary services Netwrk layer (layer 3): B-channel Prtcl t be used Lgical channels Prcedures fr restart, virtual calls, data transfer, and reset Prcedures t be used General packet frmat Frmat f CALL REQUEST/INCOMING CALL packets Flw cntrl parameters Flw cntrl parameter negtiatin Maximum length f user data field Windw size and numbering f packets Delivery cnfirmatin bit Cmplete packet sequence Qualifier bit Default thrughput classes assignment Errr handling Supprt f ptinal facilities f ISO/IEC Thrughput class negtiatin Fast select Transit delay selectin and indicatin Minimum thrughput class negtiatin End-t-end transit delay negtiatin Expedited data negtiatin Handling f unsupprted ptinal facilities f ISO/IEC 8208 [20] Supprt f the OSI Cnnectin-mde netwrk service General Additinal D-channel requirements (netwrk layer) Cding f LLC infrmatin element Cnveyance f NSAP addresses Nn-use f User-t-User signalling supplementary service Mapping f cause values t CONS reasns Additinal B-channel requirements (netwrk layer) Cnveyance f NSAP addresses Optinal facilities f ISO/IEC Thrughput class negtiatin Fast select Transit delay selectin and indicatin Minimum thrughput class negtiatin End-t-end transit delay negtiatin Expedited data negtiatin Interwrking with calling terminals nt supprting CONS Thrughput Quality Of Service (QOS) parameters Transit delay QOS parameter... 40

5 Page Transprt layer (layer 4) General The ISDN telematic transprt service Supervisry timers Cnnectin establishment - calling terminal: transprtselectr Cnnectin establishment - called terminal: transprtselectr Transprt prtcl Identificatin Supprt f the OSI Cnnectin-mde Transprt Service Expedited data transfer Classes and ptins TPDU Numbering Explicit flw cntrl Cnnectin establishment - calling terminal: Transprt- Selectr Cnnectin establishment - called terminal: transprtselectr Supervisry timers (TS) Length indicatr value Transprt prtcl identificatin Treatment f prtcl errrs...43 Annex A: Prfile Requirements List...44 A.1 General...44 A.2 Relatinship between RL and PICS prfrmas...44 A.3 Tables fr the physical layer...44 A.4 Tables fr the link layer: D-channel...44 A.5 Tables fr the link layer: B-channel...45 A.5.1 Requirements List fr ISO/IEC 8885 [23]...45 A.5.2 Requirements List fr ISO/IEC 7776 [17]...45 A.5.3 ISO/IEC 7776 [17] Majr capabilities...45 A.5.4 Basic/extended peratin...46 A.5.5 Link set-up...46 A.5.6 Timers, etc A.6 Tables fr the netwrk layer: D-channel...47 A.6.1 Relatinship between RL and PICS prfrmas...47 A.6.2 Rles...47 A.6.3 Majr capabilities f the user rle...48 A.6.4 Subsidiary capabilities f the user rle...48 A.6.5 Infrmatin elements in SETUP received by the user...49 A.6.6 Infrmatin elements in SETUP transmitted by the user...49 A.6.7 Bearer capability...50 A.6.8 High layer cmpatibility...51 A.6.9 Lw layer cmpatibility...52 A.7 Tables fr the netwrk layer: B-channel...55 A.7.1 Requirements List fr ISO/IEC 8208 [20]...55 A General DTE characteristics...56 A Call set-up...56 A Call clearing...57 A Resetting f lgical channels...57 A Errr prcedures...57 A Sending data...58 A Receiving data...59 A Delivery cnfirmatin...59 A Values f cause and diagnstic cde fields...60

6 Page 6 A Facilities sent in CALL REQUEST packets A Facilities sent in CALL ACCEPT packets A Facilities sent in CLEAR REQUEST packets A Facilities received in INCOMING CALL packets A Facilities received in call cnnect packets A Facilities received in clear indicatin packets A Facilities received in CLEAR CONFIRMATION packets A Registratin-facilities sent in REGISTRATION REQUEST packets A Registratin-facilities sent in registratin cnfirmatin packets A Registratin-facilities received in registratin cnfirmatin packets A Registratin-facilities received in registratin request packets A Values fr flw cntrl parameters, etc A Timers, Retransmissin Cunts and lgical channel ranges A.7.2 Requirements List fr ISO/IEC 8878 [22] A Majr capabilities A Netwrk Address mapping A Interrupt packet A Data packet with D-bit set t A Facilities missing in an INCOMING CALL packet A Restrictins n ISO/IEC 8208 [20] requirements A.8 Tables fr the transprt layer: B-channel A.8.1 Requirements List fr ITU-T Recmmendatin T.70 [3] A.8.2 Requirements List fr ISO/IEC 8073 [19] A Classes implemented A Parameter values fr CR TPDU A Supprted parameters fr class 0 TPDUs A Class negtiatin - initiatr A Class negtiatin - respnder A Actin n receipt f a prtcl errr A Timers and prtcl parameters Annex B: Prfile specific ICS prfrma B.1 General B.2 Cpyright release fr prfile specific ICS prfrma B.3 Cnfrmance B.4 Identificatin B.4.1 Identificatin f Implementatin Under Test (IUT) B.4.2 Identificatin f the prfile B.5 Prfile specific ICS prfrma structure and cntents B.5.1 General B.5.2 Pre-printed table cntents B.5.3 The status clumn B.5.4 Table and item identificatin B.6 Guidance fr cmpletin f the prfile specific ICS prfrma B.7 Prfile specific ICS tables B.7.1 Supprted prtcls B.7.2 Prfile specific ICS prfrma fr the physical layer B.7.3 Prfile specific ICS prfrma fr the link layer: D-channel B.7.4 Prfile specific ICS prfrma fr the link layer: B-channel B Terminal type selectin B Receipt f XID frames with FIS = B Establishment f data link B System parameters... 82

7 Page 7 B.7.5 Prfile specific ICS prfrma fr the netwrk layer: D-channel...82 B Cmpatibility infrmatin prvided by the calling terminal...82 B Cmpatibility checking by the called terminal...83 B Interwrking with ther netwrks...83 B Use f ISDN supplementary services...83 B.7.6 Prfile specific ICS prfrma fr the netwrk layer: B-channel...84 B.7.7 Prfile specific ICS prfrma fr the CONS...85 B.7.8 Prfile specific ICS prfrma fr the transprt layer...86 B Prfile specific ICS prfrma fr the ISDN telematic transprt service...86 B Prfile specific ICS prfrma fr the COTS...89 Annex C: Applicability f this ETR...90 Annex D: Bibligraphy...91 Histry...94

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9 Page 9 Frewrd This ETSI Technical Reprt (ETR) has been prduced by the Terminal Equipment (TE) Technical Cmmittee f the Eurpean Telecmmunicatins Standards Institute (ETSI). Intrductin T permit the effective interchange f nn-vice (telematic) infrmatin between tw terminal equipments, cnnected tgether by means f an Integrated Services Digital Netwrk (ISDN) bearer service cnnectin, an end-t-end prtcl fr cntrlling the data transmissin prcess needs t be agreed. The basic reference mdel f Open System Intercnnectin (OSI), the OSI mdel, prvides a framewrk in which such prtcls can be agreed. The OSI mdel is an internatinally standardized descriptin f the activities and functins necessary t allw systems t interwrk using telecmmunicatins services. Hwever ther (nn-osi) methds are available and the ISDN circuit-mde 64 kbit/s unrestricted bearer services may be used in cnjunctin with any end-t-end prtcls. This ETR recmmends, fr use n the ISDN, a set f prtcls based upn the structure defined by the lwer 4 layers f the OSI mdel. It takes int accunt the lnger transmissin delays which are encuntered n cnnectins ruted via satellite systems. The prtcls reflect: a) the imprtance f "pen systems" as a means f achieving Eurpe-wide and Wrld-wide infrmatin interchange; and b) the psitin f ISDN as a means fr prviding Eurpe-wide and Wrld-wide telecmmunicatins services; and c) the pssibility that internatinal cnnectins will include a satellite link and the need fr glbal applicatins which use the ISDN t perate efficiently ver them. Hwever, the need t ensure cmpatibility with existing prtcls has nt been verlked. Sufficient flexibility has been incrprated t allw cmmunicatin with systems that are nt necessarily OSI cnfrmant and with thse which cnfrm t existing standards, such as ETS [1]. Prtcls t supprt the data link service, the netwrk service and the transprt service can be individually designed fr each telematic applicatin. Hwever, there are benefits t be gained frm using cmmn prtcls that generally satisfy the requirements f all the applicatins cncerned. The bjective f this ETR is t define a cmmn prtcl stack and t specify, as far as pssible, a cmmn prtcl at each layer f the stack t supprt all future telematic applicatins with ptinal features t enable interperatin with existing applicatins. This will: a) mre readily allw data interchange between systems prviding multiple services; and b) limit the number f variants, enabling a standard implementatin t be realized, thereby reducing csts (f bth cnstructin and testing). This ETR describes a set f prtcls, up t layer 4, which may be used by terminal equipment with telematic functins attached t the Eurpean ISDN. The prtcls are based upn ITU-T Recmmendatin T.90 [28] and ETS [1], Ed 1. Requirements previusly cntained in ENV (see annex D). are als included. T braden the scpe f this recmmendatin, giving it a mre general ISDN applicatin, the lwer layer prtcls are specified such that they can be used by any type f telematic terminal regardless f whether a transprt service is specified fr that applicatin. In ther wrds, the layer 2 and 3 requirements are fr general applicatin and are independent f the higher layer aspects f the prtcl stack f each applicatin. Furthermre, the type selectin prcedure fr terminals at call set up allws applicatins using prtcls that are nt within the scpe f this recmmendatin t be detected. Such prtcls may be implemented in additin t thse recmmended in this ETR as part f a multifunctin terminal. Fr histric reasns the prtcls t be implemented in existing facsimile grup 4, file transfer and Syntax-based Videtex applicatins are defined in ETS [1].

10 Page 10 A TE implementing data link cntrl prcedures in accrdance with ITU-T Recmmendatin X.75 (see annex D) as mdified by Editin 1 f ETS [1], des nt cnfrm t the requirements f this recmmendatin Hwever, a TE implementing data link cntrl prcedures in accrdance with this ETR will be able t interwrk (but pssibly less efficiently) with such terminal equipment. The requirements recmmended in this ETR are sufficiently general t be applicable t ITU telematic services, apprpriate OSI-based applicatins and future multimedia applicatins. In additin prcedures are defined t enable cmmunicatin with grup 3 facsimile terminals (G3C and G3F) perating in accrdance with ITU-T Recmmendatins. Sme existing telematic applicatins d nt include a transprt layer (layer 4) in their prtcl stack fr end-t-end cmmunicatin. In this case the next higher layer prtcl fr that applicatin maps directly n t the layer 3 prtcls. The prtcl defined in subclause 4.8 f this recmmendatin is fr thse terminals that require an intermediate layer between the higher layers (5 t 7) and layer 3. It is recgnized that whilst many future develpments are likely t be based upn the OSI mdel, sme future applicatins (as sme existing applicatins) will emply a minimal transprt service and sme (e.g. like, Videtex and Eurfile Transfer) might nt define any kind f transprt layer. Similarly, sme existing (and pssibly future) applicatins d nt cnfrm entirely t the requirements f the OSI mdel. All such applicatins shuld be able t perate ver the ISDN and be capable f interchanging data with ne anther. This implies the need fr all multi-functin TE t be capable f mdifying their behaviur t cnfrm t the requirements f each f the applicatins supprted. T increase the prbability f successful calls a single default prtcl stack, with a single default set f parameters at each layer, is recmmended fr use n the B-channel. Applicatin specific variatins t the recmmended prtcls, if necessary, are expected t be specified elsewhere. This ETR cntains a recmmendatin fr the applicatin f base standards t permit efficient interwrking between a TE with telematic functins and the ISDN and between tw TE telematic functins via an ISDN cnnectin. Such a cnnectin may be a whlly terrestrial cnnectin r it may include a satellite system. Optins are defined which enable the system t select thrughput parameters that permit efficient peratin ver mst types f cnnectin. The ptimizatin f thrughput fr a particular applicatin is utside the scpe f this ETR. Implementatin f this recmmendatin requires reference t the apprpriate base standards.

11 Page 11 1 Scpe This ETSI Technical Reprt (ETR) cntains a recmmended methd f extending the lwer layer prtcls specified in ETS [1] t cver, in particular, new nn-vice applicatins and t include requirements fr efficient infrmatin transfer ver lng cnnectins, typically when ruted via a satellite system. The recmmendatin includes a set f prtcls up t and including layer 4 f the Integrated Services Digital Netwrk (ISDN) Prtcl Reference Mdel (PRM) fr use with Terminal Equipment (TE) with telematic functins (telematic terminals), attached t the pan-eurpean ISDN. It cntains a specificatin f the prfile (including additinal aspects nt specified in the base standards t which the prfile refers), the Requirements List (RL) and the prfile specific Implementatin Cnfrmance Statement (ICS) fr the prfile. Tgether, clause 4 and annex A specify the cmplete requirements fr the implementatin f the prfile. The prtcls recmmended in this ETR d nt cnstitute a nrmative requirement and are, therefre, published as an ETR. This ETR defines a prfile cntaining: - lwer layer prtcls which may be used n the D-channel t establish an ISDN (public and/r private) circuit-mde cnnectin between tw terminal equipments incrprating telematic functins; and - lwer layer prtcls which may be (subsequently) used n the B-channel fr end-t-end cmmunicatin between the telematic functins f the tw terminal equipments, specified t supprt the prvisin f the Open System Intercnnectin (OSI) Cnnectin-mde Netwrk Service and t supprt the higher layer prtcls f the full range f ISDN telematic applicatins. The prtcls recmmended in this ETR may be applied t any TE that supprts ne r mre telematic functins. Applicatin specific requirements, where required fr particular telematic functins, are expected t be cvered elsewhere. The migratin f existing telematic applicatins r services (e.g. Grup 4 facsimile, videtex, etc.) t the use f the prtcls defined in this ETR wuld need certain additinal requirements t be specified. Ntes in the text identify where such additinal requirements may be necessary. When implemented, the prtcls recmmended in this ETR shuld be applied t terminal equipment with telematic functins cnnected via an interface at the S reference pint, at the T reference pint, r at the cincident S and T reference pint, as defined in ITU-T Recmmendatin I.411 [2]. These interfaces may be either the Basic Access r the Primary Rate Interface. The scpe f this recmmendatin als includes interfaces f Private Telecmmunicatin Netwrk Exchanges (PTNX) at the T and Q reference pints (as specified in ISO/IEC [27]) in s far as is necessary fr the crrect peratin f calls between telematic terminals. The requirements fr terminal equipment intended fr attachment t nn-isdns (e.g. PSTN, PDN) are cvered elsewhere. The scpe f the prtcls recmmended in this ETR is limited t demand calls using the circuit-mde 64 kbit/s unrestricted digital infrmatin bearer service and t the Data Terminal Equipment (DTE)-t-DTE case f the netwrk layer peer entities n the B-channel cnnectin. The requirements included in this recmmendatin are based n ETSs, Internatinal Standards r ITU-T Recmmendatins. In particular, they are based n the requirements cntained in ITU-T Recmmendatin T.90 [28] and, where apprpriate, ITU-T Recmmendatin X.224 [29]. This recmmendatin fllws the methdlgy specified in ISO/IEC TR It prvides the RL and the prfile specific ICS prfrma in cmpliance with the relevant requirements, and in accrdance with the relevant guidance, given in ISO/IEC [26] and ETS (see annex D). Annex A cntains the prfile RL and annex B cntains the prfile specific ICS prfrma. The supplier f an implementatin that is claimed t cnfrm t the requirements f this recmmendatin is required t cmplete a cpy f the ICS prfrma prvided in annex B and is required t prvide the infrmatin necessary t identify bth the supplier and the implementatin. This recmmendatin des nt identify all the standards t which TE intended fr cnnectin t the ISDN need t cmply. In particular, this ETR des nt identify standards related t safety and prtectin, and electrmagnetic cmpatibility (EMC) fr the physical interface(s) f the equipment. Neither des it identify regulatry requirements with which such equipment may be required t cmply.

12 Page 12 2 References This ETR incrprates by dated r undated reference, prvisins frm ther publicatins. These references are cited at the apprpriate places in the text and the publicatins are listed hereafter. Fr dated references, subsequent amendments t r revisins f any f these publicatins apply t this ETR nly when incrprated in it by amendment r revisin. Fr undated references the latest editin f the publicatin referred t applies. These references becme nrmative in the event that the recmmendatins cntained in this ETR are implemented. [1] ETS (1992): "Integrated Services Digital Netwrk (ISDN); ISDN lwer layer prtcls fr telematic terminals". [2] ITU-T Recmmendatin I.411 (1988): "ISDN user-netwrk interfaces - Reference cnfiguratins". [3] ITU-T Recmmendatin T.70 (1988): "Netwrk-independent basic transprt service fr the telematic services". [4] ITU-T Recmmendatin X.25 (1988): "Interface between Data Terminal Equipment (DTE) and Data Circuit terminating Equipment (DCE) fr terminals perating in the packet mde and cnnected t public data netwrks by dedicated circuits". [5] ETS (1992): "Integrated Services Digital Netwrk (ISDN); Primary rate user-netwrk interface, Layer 1 specificatin and test principles". NOTE 1: Including Amendments 1 and 2. [6] ETS (1992): "Integrated Services Digital Netwrk (ISDN); Basic usernetwrk interface, Layer 1 specificatin and test principles". NOTE 2: Including Amendments 1 and 2. [7] ETS (1993): "Private Telecmmunicatin Netwrk (PTN); Specificatin, functinal mdels and infrmatin flws; Identificatin supplementary services; ECMA-ISSD" (ISO/IEC (1994) mdified). [8] ETS (1992): "Private telecmmunicatin netwrk (PTN); Signalling prtcl at the S-reference pint; Circuit mde basic services ECMA-SSIG-BC". [9] ETS (1995): "Integrated Services Digital Netwrk (ISDN); Interwrking between public ISDNs and private ISDNs fr the prvisin f telecmmunicatins services; General aspects". [10] prets : "Integrated Services Digital Netwrk (ISDN); Digital Subscriber Signalling System N. ne (DSS1) prtcl; Data link layer; Part 1: General aspects" (ITU-T Recmmendatin Q.920 (1993) mdified). [11] prets : "Integrated Services Digital Netwrk (ISDN); Digital Subscriber Signalling System N. ne (DSS1) prtcl; Data link layer; Part 2: General prtcl specificatin. (ITU-T Recmmendatin Q.921 (1993) mdified)". [12] prets : "Integrated Services Digital Netwrk (ISDN); Digital Subscriber Signalling System N. ne (DSS1) prtcl; Data link layer; Part 4: Prtcl Implementatin Cnfrmance Statement (PICS)". [13] prets : "Integrated Services Digital Netwrk (ISDN); Digital Subscriber Signalling System N. ne (DSS1) prtcl; Signalling netwrk layer fr circuit-mde basic call cntrl; Part 1: Prtcl specificatins" (ITU-T Recmmendatin Q.931(1993) mdified).

13 Page 13 [14] prets : "Integrated Services Digital Netwrk (ISDN); Digital Subscriber Signalling System N. ne (DSS1) prtcl; Signalling netwrk layer fr circuit-mde basic call cntrl; Part 2: Specificatins and Descriptin Language (SDL) diagrams". [15] prets : "Integrated Services Digital Netwrk (ISDN); Digital Subscriber Signalling System N. ne (DSS1) prtcl; Signalling netwrk layer fr circuit-mde basic call cntrl; Part 3: Prtcl Implementatin Cnfrmance Statement (PICS)". [16] ISO/IEC 4335 (1993): "Infrmatin technlgy - Telecmmunicatins and infrmatin exchange between systems - High-level Data Link Cntrl (HDLC) prcedures - Elements f prcedures" (5th editin). [17] ISO/IEC 7776 (1994): "Infrmatin technlgy - Telecmmunicatins and infrmatin exchange between systems - High-level data link cntrl prcedures - Descriptin f the X.25 LAPB-cmpatible DTE data link prcedures", 2nd editin. [18] ISO/IEC 8072 (1986): "Infrmatin technlgy - Open Systems Intercnnectin - Transprt Service definitin". [19] ISO/IEC 8073 (1992): "Infrmatin technlgy - Telecmmunicatins and infrmatin exchange between systems - Open Systems Intercnnectin - Prtcl fr prviding the cnnectin-mde transprt service". NOTE 3: This reference includes ISO/IEC 8073, Technical Crrigendum 2 (1994), "Infrmatin technlgy - Telecmmunicatins and infrmatin exchange between systems - Open Systems Intercnnectin - Prtcl fr prviding the cnnectin-mde transprt service", 3rd editin. [20] ISO/IEC 8208 (1995): "Infrmatin technlgy - Data cmmunicatins - X.25 Packet Level Prtcl fr Data Terminal Equipment", 3rd editin. [21] ISO/IEC 8348 (1993): "Infrmatin technlgy - Open Systems Intercnnectin - Netwrk Service Definitin". [22] ISO/IEC 8878 (1992): "Infrmatin prcessing systems - Telecmmunicatins and infrmatin exchange between systems - Use f X.25 t prvide OSI cnnectin-mde netwrk service" (2nd editin). [23] ISO/IEC 8885 (1993): "Infrmatin technlgy - Telecmmunicatins and infrmatin exchange between systems - High-level data link cntrl (HDLC) prcedures - General purpse XID frame infrmatin field cntent and frmat" (3rd editin). [24] ISO/IEC 9574 (1992): "Infrmatin technlgy - Prvisin f the OSI cnnectin-mde netwrk service by packet mde terminal equipment cnnected t an Integrated Services Digital Netwrk (ISDN)" (2nd editin). [25] ISO/IEC (1994): "Infrmatin technlgy - Open Systems Intercnnectin - Cnfrmance testing methdlgy and framewrk - Part 1: General cncepts". [26] ISO/IEC (1994): "Infrmatin technlgy - Open Systems Intercnnectin - Cnfrmance testing methdlgy and framewrk - Part 7: Implementatin Cnfrmance Statements". [27] ISO/IEC (1994): "Infrmatin technlgy - Private Integrated Services Netwrk - Reference Cnfiguratin Part 1: Reference Cnfiguratin fr PISN Exchanges (PINX)".

14 Page 14 [28] ITU-T Recmmendatin T.90 (1994): "Characteristics and prtcls fr terminals fr telematic services in ISDN". [29] ITU-T Recmmendatin X.224 (1993): "Infrmatin technlgy Open systems intercnnectin Prtcl fr prviding the OSI cnnectin-mde transprt service". [30] ITU-T Recmmendatin I.333 (1988): "Terminal selectin in ISDN". [31] ITU-T Recmmendatin X.200: "Infrmatin technlgy Open Systems Intercnnectin Basic reference mdel: The basic mdel". 3 Definitins and abbreviatins 3.1 Definitins Fr the purpses f this ETR, the definitins in ISO/IEC [25] apply in additin t the fllwing: lwer layer prtcl: A prtcl defined fr use in ne f layers 1 t 4 f the prtcl reference mdel fr ISDN. Open System Intercnnectin (OSI): The cncept f intercnnecting systems in accrdance with the architecture described in ITU-T Recmmendatin X.200 [31] telematic functin: A functin, excluding telephny, fr the exchange f infrmatin via telecmmunicatin netwrks. Examples f existing telematic functins include facsimile, file transfer, message handling and videtex functins. telematic terminal: A TE with ne r mre telematic functins. NOTE 1: NOTE 2: Where the term "telematic terminal" is used in this ETR, it may be interpreted t mean equally either "a terminal equipment with ne r mre telematic functins", r "an OSI reference end system as defined in Memrandum M-IT-02 (see annex D)". The shrtened term "terminal" and the abbreviatin "DTE" are als used in this ETR t imprve clarity; in bth cases they shuld be interpreted t mean "telematic terminal". Terminal Equipment (TE): Equipment intended t be cnnected t a telecmmunicatin netwrk in rder t send and/r receive infrmatin. 3.2 Abbreviatins Fr the purpses f this ETR, the fllwing abbreviatins are used: BC Bearer Capability CC Cnnectin Cnfirm CONS COnnectin-mde Netwrk Service CR Cnnectin Request DCE Data Circuit-terminating Equipment DLS Data Link Subfield DM Discnnected Mde DR TPDU Discnnect Request TPDU DTE Data Terminal Equipment ER TPDU Errr TPDU FI Frmat Identifier FIS Frmat Identifier Subfield FRMR Frame Reject FTAM File Transfer and Access Management G3C Grup 3 facsimile (ITU-T Recmmendatin T.30 annex C, digital mde) G3F Grup 3 facsimile (ITU-T Recmmendatin T.4 annex F) G3V Grup 3 facsimile (ITU-T Recmmendatin T.30 annex C, analgue mde) G4 Grup 4 facsimile

15 Page 15 HDLC HIC HLC HOC HTC ICS ISDN ITSTC IUT LAPD LI LIC LLC LLI LOC LTC MFE NIC NCMS NSAP OSI P/F PAD PDU PICS PRM PSPDN PSTN PTN PTNX QOS RL SABM SABME SDL SPI TDSAI TE TPDU TPI TR UA UDS XID High-level Data Link Cntrl Highest Incming Channel Higher Layer Cmpatibility Highest Outging Channel Highest Tw-way channel Implementatin Cnfrmance Statement Integrated Services Digital Netwrk CEN/CENELEC/ETSI Infrmatin Technlgy Steering Cmmittee Implementatin Under Test Link Access Prcedure n the D-channel Length Indicatr Lwest Incming Channel Lwer Layer Cmpatibility Lgical Link Identifier Lwest Outging Channel Lwest Tw-way Channel Multiple Frame Establishment Netwrk Independent Clck Netwrk Cnnectin Management Subprtcl Netwrk Service Access Pint Open Systems Intercnnectin Pll/Final Packet Assembler / Dis-assembler Prtcl Data Unit Prtcl Implementatin Cnfrmance Statement Prtcl Reference Mdel Packet Switched Public Data Netwrk Public Switched Telephne Netwrk Private Telecmmunicatin Netwrk Private Telecmmunicatin Netwrk exchange Quality Of Service Requirements List Set Asynchrnus Balanced Mde Set Asynchrnus Balanced Mde Extended Specificatin and Descriptin Language Subsequent Prtcl Identifier Transit Delay Selectin And Indicatin Terminal Equipment Transprt Prtcl Data Unit Telematics Prfile Identifier Technical Reprt Unnumbered Acknwledgement User Data Subfield exchange IDentificatin 4 Cnfrmance requirements 4.1 Prtcl stack Supprted prtcls TE with telematic functins and attached t an ISDN (public r private) via an interface at the S reference pint, the T reference pint, r the cincident S and T reference pint, shuld supprt the prtcls defined by the Standards shwn in figure 1. Annex C t this ETR cntains a descriptin f the scenari t which this recmmendatin may be applied NOTE: Existing types f telematic terminal, which cmply with ETS [1], may als be attached t an ISDN at these pints.

16 Page 16 ISDN PRM layer 4 ITU-T Recmmendatin T.70 [3], r ISO/IEC 8072 [18] & ISO/IEC 8073 [19] (nte 1) 3 ETS (see annex D) (nte 2) ISO/IEC 9574 [24] ISO/IEC 8878 [22] ISO/IEC 8208 [20] 2 ETS (see annex D) ISO/IEC 8885 [23] ISO/IEC 7776 [17] 1 ETS [5] r ETS [6] Cntrl Plane (D-channel prtcl) User Plane (B-channel prtcl) NOTE 1: It is nt essential that all telematic applicatins use the same transprt layer (layer 4) prtcls. (Fr example, Syntax- Based Videtex and Eurfile use n transprt service. NOTE 2: At the S reference pint, the requirements f ETS (see annex D) are mdified; see subclause Figure 1: Prtcl stack at the interface f ISDN TE with telematic functins Relatinship between prtcls Operatins perfrmed in the User Plane shuld be c-rdinated with peratins perfrmed in the Cntrl Plane. The prcedure shuld be as described belw: - If a B-channel cnnectin has nt previusly been established, a calling TE shuld cause the ISDN D-channel signalling prcedure fr switched circuit-mde cnnectins t be used t establish a B-channel cnnectin. This shuld be carried ut accrding t the requirements specified in subclause If a B-channel cnnectin already exists, r fllwing establishment f the B-channel cnnectin as specified abve, the B-channel inband prcedures shuld be carried ut accrding t the requirements specified in subclauses 4.4 and At the end f cmmunicatin the call must be cleared. The B-channel data link shuld nt be discnnected befre the B-channel virtual call has been cleared. The B-channel shuld nt be discnnected until the data link has been discnnected and the B-channel has returned t the idle channel state. 4.2 Physical interface (layer 1) The physical interface f the TE shuld be an ISDN basic access implemented accrding t ETS [6] r an ISDN Primary Rate Interface implemented accrding t ETS [5]. 4.3 Link layer (layer 2): D-channel At layer 2, the data link prcedures fr the D-channel (Link Access Prcedure n the D-channel (LAPD)) shuld be thse specified in ETS [10] and ETS [11].

17 Page Link layer (layer 2): B-channel Prtcl t be used Once a cnnectin has been established between the calling TE and the called TE a High-level Data Link Cntrl (HDLC) prtcl shuld be perated n the B-channel. This prtcl shuld be the prtcl specified in ISO/IEC 7776 [17] mdified by the requirements in subclause Prir t the establishment f the data link cnnectin the fllwing prcedures shuld take place: - achievement f ctet alignment between the TEs, as specified in subclause 4.4.2; and - ptinally, terminal type selectin and negtiatin f the essential data link parameters, as specified in subclauses and respectively. NOTE: Prvisin fr inband terminal type selectin and negtiatin f essential data link parameters is strngly recmmended. It maximizes the prbability f successful end-t-end cmmunicatin between telematic terminals designed t different standards, and between telematic terminals cnnected t different netwrks Octet alignment T ensure ctet alignment between the terminals at each end f the cnnectin, the prcedure described in this subclause shuld be used fr establishing end-t-end cmmunicatin n the B-channel Idle channel state A TE shuld clse the receiver n the B-channel and transmit cntinuus "1" bits (idle channel state) n the B-channel until a B-channel cnnectin t the remte TE has been established (i.e. until the circuit-switched ISDN call established by the netwrk layer prtcl n the D-channel (see subclause 4.5) has entered the Active state) Active channel state - called terminal After accepting a call (as described in subclause ) a called terminal shuld pen the receiver n the B-channel, and enter the active channel state by transmitting cntiguus flags (interframe timefill, as defined in subclause f ISO/IEC 7776 [17]) Active channel state - calling terminal When a B-channel cnnectin has been established (i.e. after a CONNECT message has been received n the D-channel) a calling terminal shuld pen the receiver n the B-channel and enter the active channel state by transmitting cntiguus flags (interframe timefill, as defined in subclause f ISO/IEC 7776 [17]) Recgnitin f ctet alignment It is desirable that the calling terminal shuld nt send any HDLC frames until at least 64 cntiguus flags have been received n the B-channel. The calling terminal may then send an exchange IDentificatin (XID) frame (subclause 4.4.3) r initiate the setting up f the data link (subclause 4.4.6). NOTE: Recgnitin f at least 64 cntiguus flags enables the terminal t distinguish between absence f flags and transmissin errrs. Cntiguus flags are nt available when interwrking ccurs with a netwrk having restricted bearer capability. The absence f cntiguus flags n the B-channel is nt, therefre, necessarily an indicatin f a failure cnditin. Interwrking with a netwrk having restricted bearer capability is utside the scpe f this ETR. In additin, by waiting fr 64 flags befre sending a frame, cmpatibility with facsimile "G3C" terminals will be achieved.

18 Page Return t idle channel state A TE shuld return a B-channel t the idle channel state (see subclause ) when the circuit-switched ISDN call established by the netwrk layer prtcl n the D-channel (see subclause 4.5) leaves the Active state (i.e. when call clearing cmmences). A TE shuld als return a B-channel t the idle channel state (see subclause ) if the receiver detects the idle channel cnditin (cntinuus "1" bits) fr a perid f time equivalent t timer T3 (see subclause ) Terminal type selectin General Terminal type selectin using an inband (n the B-channel) mechanism is an ptinal feature which may be carried ut n a call-by-call basis. If such a prcedure is used, it shuld cmply with the requirements f this subclause. NOTE 1: NOTE 2: NOTE 3: NOTE 4: The use f inband prcedures may nt be necessary if there is prir agreement between the calling and called parties n the terminal type and data link parameters. Such agreement may be achieved thrugh utband negtiatin (see subclause ) r sme ther means which is utside the scpe f this ETR. If used hwever, the inband negtiatin verrides any prir agreement. The circumstances f when and if the inband prcedure wuld be used are applicatin dependant and are utside the scpe f this ETR (inband terminal type selectin, fr example, is nt supprted by syntax based Videtex and Eurfile; it is ptinal in a facsimile grup 4 terminal). The use f an inband selectin mechanism can maximize the prbability f successful end-t-end cmmunicatin between telematic terminals designed t different standards, r between telematic terminals cnnected t different netwrks. The utband cmpatibility checking mechanism, using infrmatin elements f the D-channel layer 3 prtcl as described in subclause 4.5.2,.may nt be universally available and where it is available may nt always be capable f unambiguusly defining the telematic service required and the end-t-end prtcl characteristics. The XID prcedure specified in this subclause and in subclause is a specific applicatin f the general purpse XID prcedure defined in ISO/IEC 8885 [23]. Based n the prcedure described in annex F f ITU-T Recmmendatin T.90 [28], it permits inband terminal type selectin and negtiatin f the essential data link parameters between tw telematic terminals. This prcedure can nly be used by applicatins fr which terminal type cdes have been allcated (see table 2 in subclause ). NOTE 5: This prcedure supersedes prcedures based n annex C f ITU-T Recmmendatin T.90 [28]. New designs f TE shuld nt supprt the transmissin f XID frames with a value f hexadecimal 82 in the Frmat Identifier Subfield (FIS). Hwever, fr backwards cmpatibility, new terminal designs may wish t supprt the recgnitin f received XID frames f this type. Requirements related t the recgnitin f such frames are cntained in subclause Terminal type selectin shuld be implemented using the XID cmmand/respnse frame specified in ISO/IEC 4335 [16]. The frmat and cntent f the infrmatin field are described in subclause The single-frame exchange negtiatin prcedure specified in clause 7 f ISO/IEC 8885 [23] shuld be used, as amended by the requirements f the fllwing subclauses.

19 Page Prcedure at calling terminal Terminal type selectin shuld be carried ut after the physical B-channel cnnectin has been established and ctet alignment btained, but befre the initiatin f data link set-up n the B-channel. The calling terminal shuld send an XID cmmand frame with the Pll/Final (P/F) bit f the cntrl field set t "1". The User Data Subfield (UDS) shuld cntain a Telematics Prfile Identifier (TPI) blck indicating the terminal type r types supprted (see subclause ) Prcedure at called terminal A called terminal receiving an XID cmmand frame, encded as described in subclause 4.4.5, shuld acknwledge receipt f the frame. It des this by sending an XID respnse frame with the P/F bit f the cntrl field set t "1". The UDS shuld cntain a TPI blck indicating a single terminal type. The terminal type indicated shuld be the first type, selected frm the preference list sent by the calling terminal (see subclause ), that the called terminal is able t supprt. Alternatively, the UDS may cntain a list f terminal types that the called terminal can supprt. A called terminal receiving an Set Asynchrnus Balanced Mde (SABM) r Set Asynchrnus Balanced Mde Extended (SABME) cmmand frame whilst waiting fr an XID cmmand frame shuld assume that the calling terminal des nt supprt XID cmmand frame prcedures. The called terminal then immediately cntinues with initiatin f data link set-up; it shuld cntinue t behave as the called terminal, as described in subclause Selectin by calling terminal If nly a single terminal type is indicated in the XID respnse frame, the calling terminal may accept this type r it may clear the call. If several terminal types are indicated in the XID respnse frame, the calling terminal may select ne f the terminal types ffered, r it may clear the call. In bth cases, if the calling terminal decides t prceed with the call it sets up the data link accrding t subclause T maximize the prbability f successful interwrking, the defined terminal types (see table 2 in subclause ) include terminal types that are nt specifically within the scpe f this recmmendatin e.g. facsimile grup 3C. If the ffered terminal type is utside the scpe f this recmmendatin, and the calling terminal supprts the required functinality, the calling terminal may still chse t prceed with the call. In this case, the subsequent prcedures are utside the scpe f this ETR. NOTE: Sme TE that can be called will nt cnfrm t the requirements f this recmmendatin.. Such TE may nt recgnize XID cmmand frames f the type described in subclause , and might respnd with a Discnnected Mde (DM) respnse frame with the P/F bit set t "1". If the calling terminal receives a DM respnse frame, it shuld assume the called terminal has nt recgnized the XID frame. If, after a perid f time equal t 3 times the value f timer T1, the calling terminal has received n respnse, the calling terminal shuld assume the called terminal has nt recgnized the XID frame. In either case the calling terminal shuld cntinue by setting up the data link accrding t subclause Negtiatin f essential data link parameters During terminal type selectin Negtiatin f the essential data link parameters is ptinally permitted if the applicatin uses the terminal type selectin prcedure (subclause 4.4.3). Such negtiatin shuld be undertaken using the same XID frame as is used fr terminal type selectin. The XID frame transmitted by the calling terminal shuld indicate, by means f apprpriate encding in the Data Link Subfield (DLS), which mdes f peratin (subclause ) the calling terminal supprts. The XID frame shuld als indicate the maximum windw size the calling terminal can supprt (subclause ).

20 Page 20 In accrdance with ISO/IEC 8885 [23] the XID respnse frame sent by the called terminal determines the parameter values t be used by bth terminals. It shuld indicate acceptance f extended (mdul 128) peratin if this mde was ffered by the calling terminal and is supprted by the called terminal. Otherwise, the respnse shuld indicate acceptance f basic (mdul 8) peratin. The value fr the k parameter in the XID respnse frame shuld be equal t r less than the value f the equivalent k parameter in the XID cmmand frame. The requirements specified in subclause shuld be taken int accunt when setting the value f k in the respnse frame. If the calling terminal receives a DM respnse frame, it shuld assume the called terminal has nt recgnized the XID frame. If, after a perid f time equal t 3 times the value f timer T1, the calling terminal has received n respnse, the calling terminal shuld assume the called terminal has nt recgnized the XID frame. In either case the calling terminal shuld cntinue by setting up the data link accrding t subclause On receipt f XID frame with FIS = 82 A called terminal receiving an XID cmmand frame in which the FIS is encded with a value f hexadecimal 82 may respnd with either a DM respnse frame r an XID respnse frame. In the latter case the requirements in the remainder f this subclause apply. NOTE: This prcedure is included t permit backwards cmpatibility with calling TE designed t the 1992 versin f ITU-T Recmmendatin T.90 [28]. The frmat f the XID respnse frame shuld be similar t that described in subclause belw. The frame shuld cntain a FIS, cded with value hexadecimal 82, and a Data Link Subfield (DLS), but n User Data Subfield (UDS). In accrdance with ISO/IEC 8885 [23] the XID respnse frame sent by the called terminal shuld determine the parameter values t be used by bth terminals. It shuld indicate acceptance f extended (mdul 128) peratin if this mde was ffered by the calling terminal and is supprted by the called terminal. Otherwise, the respnse shuld indicate acceptance f basic (mdul 8) peratin. The value fr the k parameter in the XID respnse frame shuld be equal t r less than the value f the equivalent k parameter in the XID cmmand frame. The requirements specified in subclause shuld be taken int accunt when setting the value f k in the respnse frame Cntent and frmat f the XID frame Figure 2 shws the frmat f an XID frame fr terminal type selectin. The cntent and frmat f XID cmmand and respnse frames shuld be as specified in ISO/IEC 8885 [23] with amendments as specified in this subclause. F A C FIS DLS UDS FCS F Field cntent (hexadecimal) Flags 7E Frame check sequence Calculated User data subfield Datalink layer subfield Frmat identifier subfield 84 User data identifier (FF) TPI blck (see figure 3) Reserved See subclause Cntrl Address Flags FD r F5, depending n P/F bit See subclause E Figure 2: Frmat f XID frame fr terminal type selectin

21 Page Frmat Identifier Subfield (FIS) The FIS shuld be encded as: "telematic terminal negtiatin" (hexadecimal value 84). NOTE: See ISO/IEC TR (see annex D) Data Link Subfield (DLS) Only the DLS with Grup Identifier equals "parameter negtiatin" shuld be used (hexadecimal value 80). Parameter field elements, selected frm tables 1 and 3 f ISO/IEC 8885 [23] shuld be encded as specified in table 1. Table 1: DLS parameter field elements fr negtiatin f data link parameters Name Parameter Parameter field element Value identifier HDLC ptinal functins 3 10A (mdul 8) True HDLC ptinal functins 3 10B (mdul 128) True r False, accrding t the capability f the terminal (nte 1) Windw size - transmit 7 Windw size k - transmit nte 2 Windw size - receive 8 Windw size k - receive nte 2 NOTE 1: See subclause NOTE 2: See subclause Parameter field elements f the DLS nt listed in table 1 shuld be set t the value zer by bth calling and called terminals User Data Subfield (UDS) The UDS cnsists f the user data identifier and a TPI blck. The user data identifier shuld be encded with the hexadecimal value "FF". The TPI blck cnsists f a terminal identifier, a length indicatr and ne r mre terminal type identifiers. The TPI blck shuld be structured and encded as shwn in figure 3. Terminal Length Terminal type Terminal type Reserved fr identifier indicatr identifier identifier future use Cnsists f a terminal type cde and a length indicatr. Field may be repeated several times fr a terminal with multiple capabilities. Sum f the lengths f the terminal type identifiers. 01 Hex. Figure 3: Structure f the Telematics Prfile Identifier (TPI) blck Each terminal type identifier cnsists f 2 ctets. The first ctet shuld be the terminal type ctet and shuld cntain a value indicating the terminal type. The permitted values fr terminal type are shwn in table 2. The secnd ctet (which is a length indicatr fr future expansin) shuld be set t zer.

22 Page 22 Table 2: Permitted terminal types Terminal type Hexadecimal cding (nte 1) Facsimile G4 (G4) 11 Facsimile G3 ITU-T Recmmendatin T.30 annex C (G3C) (nte 2) 12 see annex D Facsimile G3 ITU-T Recmmendatin T.4 annex F (G3F) see 13 annex D Facsimile G3 ITU-T Recmmendatin T.30 annex C (G3V) (nte 2) 14 see annex D NOTE 1: At present, terminal type cdes have nly been allcated fr varius types f facsimile terminal. Other cdes may be assigned in the future. NOTE 2: See subclause Within the TPI blck ne r mre terminal type identifiers may appear (as shwn in figure 3) t signify a terminal meeting several standards (e.g. fr facsimile transmissin). Where several pssibilities exist the terminal type identifiers shuld be in rder f preference, the mst preferable being transmitted first Data link prcedures The calling TE shuld implement the data link prcedures fr DTE/DTE peratin specified in ISO/IEC 7776 [17] with mdificatins as specified in subclauses t Mde f transmissin The requirements specified in subclauses 3.5, 3.7, 3.8, 3.9, 3.10, and 3.11 f ISO/IEC 7776 [17] shuld be met. Only the synchrnus mde f transmissin shuld be supprted Mde f peratin The requirements specified in clause 3 and subclauses 4.1 and 4.3 f ISO/IEC 7776 [17] shuld be met. Basic (mdul 8) peratin shuld be the standard (default) methd f peratin. Extended (mdul 128) peratin may als be supprted. NOTE: The use f basic (mdul 8) peratin as the standard methd f peratin maximizes cmpatibility between many different types f terminal. Hwever, it is strngly recmmended that terminals shuld als supprt extended (mdul 128) peratin t permit efficient cmmunicatin ver lng cnnectins e.g. via satellite. The use f extended (mdul 128) peratin prvides greater flexibility with regard t the chice f an ptimum windw size and packet size fr a given applicatin Frame reject respnse The requirements specified in subclauses 4.3.9, 4.4.4, and f ISO/IEC 7776 [17] shuld be met. The sender f a Frame Reject Respnse (FRMR) shuld retransmit the FRMR if timer T1 expires and initiate the link resetting prcedure if n actin has been taken by the remte terminal after the FRMR has been sent N2 times Single link prcedure The requirements specified in clause 5 f ISO/IEC 7776 [17] shuld be met. Only the single link prcedure shuld be supprted. Cnfrmity t the multilink prcedure defined in clause 6 f ISO/IEC 7776 [17] is nt required.