1、- INTERIM I-ETS 300 353 October 1998 Second Edition Source: NA Reference: RVNA-052626 ICs: 33.020 Key words: B-ISDN, ATM, AAL Broadband Integrated Services Digital Network (B-ISDN); Asynchronous Transfer Mode (ATM); Adaptation Layer (AAL) specification - type 1 ETSI Eu ropean Telecomm un icat ions S
2、tandards Institute ETSI Secretariat Postal address: F-O6921 Sophia Antipolis CEDEX - FRANCE Office address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE Internet: secretariat Q etsi.fr - http:/www.etsi.org Tel.: +33 4 92 94 42 O0 - Fax: +33 4 93 65 47 16 Copyright Notification: No p
3、ari may be reproduced except as authorized by written permission. The copyright and the foregoing restriction extend to reproduction in all media. O European Telecommunications Standards Institute 1998. All rights reserved. STD-ETSI I-ETS 300 353-ENGL 1998 W 3400855 0341701 359 M Page 2 I-ETS 300 35
4、3: October 1998 Whilst 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 Standards Making Support Dept.” at the address shown on the title page.
5、3 STD-ETSI I-ETS 300 353-ENGL 1778 I 3Y00855 03YL702 295 m Page 3 LETS 300 353: October 1998 Contents Foreword . 5 Introduction 5 1 Scope 7 2 Normative references 7 3 Definitions and abbreviations 7 3.1 Definitions 7 3.2 Abbreviations . 8 AAL twe 1 . 9 4 4.1 4.2 4.3 4.4 4.5 4.6 4.7 Service primitive
6、s provided by AAL type 1 . 9 4.1.1 AAL-UNITDATA-REQUEST 9 4.1.2 AAL-UNITDATA-INDICATION . 9 4.1.3 Definition of parameters . 10 4.1.3.1 DATA parameter 10 4.1.3.2 STRUCTURE parameter . 10 4.1.3.3 STATUS parameter . IO Information flow across the ATM-AAL boundary . 10 Primitives between the SAR sublay
7、er and the CS . 11 4.3.1 General 11 4.3.1.1 SAR-UNITDATA-INVOKE . 11 4.3.1.2 SAR-UNITDATA-SIGNAL 11 Interaction with the management and control planes 11 4.4.1 Management plane 11 4.4.2 Control plane . 12 Functions of AAL type 1 . 12 SAR sublayer . 12 4.6.1 Functions of the SAR sublayer 12 4.6.2 SAR
8、 protocol . 13 4.6.2.1 SN field 13 4.6.2.2 SNP field 13 Convergence Sublayer (CS) 15 Functions of the CS . 15 4.7.1.1 Functions of the CS for circuit transport 16 4.7.1.2 Functions of the CS for video signal transport . 17 4.7.1.3 Functions of the CS for voice-band signal transport 18 4.7.2 CS proto
9、col . 19 4.7.2.1 SC operations 19 SC operations at the receiving end . 19 Adaptive clock method 20 4.7.1 . 4.7.2.1.1 SC operations at the transmitting end 19 4.7.2.1.2 Source clock frequency recovery method . 20 4.7.2.2.1 4.7.2.2.2 SRTS method 20 4.7.2.2.3 Combination of SRTS and adaptive clock meth
10、od . 23 4.7.2.3 SDT method 23 4.7.2.4 Correction methods for bit errors and/or cell losses 25 4.7.2.4.1 Correction method for bit errors 25 4.7.2.4.2 Correction method for bit errors and cell losses without delay restrictions . 26 4.7.2.4.3 Correction method for bit errors and cell losses with delay
11、 restrictions 27 Partially filled cell method for control of SAR-PDU payload 4.7.2.2 4.7.2.5 assembly delay 30 STD-ETSI I-ETS 300 353-ENGL 3998 3400855 0343703 323 Page 4 I-ETS 300 353: October 1998 Annex A (informative): Annex B (informative): Illustration of the data unit naming convention . 32 En
12、coding and information transfer principles . 33 B.l Cell payload field encoding . 33 8.2 AAL user information transfer . 33 Annex C (informative): C.l Functional model for the circuit transport with AAL type 1 . 35 Functional model of the SAR 35 C.2 SDL of the SAR 36 Annex D (informative): Parameter
13、s for AAL type 1 protocol . 38 D.l Circuit transport 38 D.l . 1 Transport of digital channel supported by 64 kbiffs-based ISDN 38 D.1.2 D.1.3 Transport of G.707 SDH circuit . 39 Video signal transport . 39 Voiceband signal transport . 40 Transport of G.702 PDH circuit . 38 D.2 D.3 Annex E (informati
14、ve): Algorithm to detect lost and misinserted cells in AAL 1 . 41 E.l General . 41 E.2 Indications from the SAR sublayer . 41 E.3 Capabilities of the algorithms 41 E.4 The algorithms 41 Robust SN Algorithm . 41 Fast SN Algorithm . 43 E.4.1 E.4.2 Annex F (normative): Protocol Implementation Conforman
15、ce Statement (PICS) proforma for the AAL type 1 46 F.l Introduction . 46 . F.2 PICS . 46 F.2.1 SAR sublayer 46 F.2.1.2 PDUs and PDU parameters . 47 CS major capabilities 47 F.2.2.1 CS for circuit transport 47 F.2.2.1 . 1 Capabilities 47 F.2.2.1.2 Protocol parameters 48 CS for video signal transport
16、49 F.2.2.2.1 Capabilities 49 F.2.2.2.2 Protocol parameters 49 CS for voice band signal transport 50 F.2.2.3.1 capabilities 50 F.2.2.3.2 Protocol parameters 50 F.2.1.1 Capabilities . 46 F.2.2 F.2.2.2 F.2.2.3 History . 51 STDaETSI I-ETS 300 353-ENGL 1778 = 3400855 03YL704 Ob8 Page 5 LETS 300 353: Octo
17、ber 1998 Foreword This Interim European Telecommunication Standard (I-ETS) has been produced by the Network Aspects (NA) Technical Committee of the European Telecommunications Standards Institute (ETSI). Announcement date Date of adoption of this I-ETS: Date of latest announcement of this LETS (doa)
18、: 9 October 1998 3 months after ETSI publication Introduction The content of this I-ETS is derived from ITU-T Recommendation 1.363.1 8. This LETS is one of a set of I-ETSs describing different Asynchronous Transfer Mode (ATM) Adaptation Layer (AAL) types. The AAL uses the ATM layer service and offer
19、s its layer service to the higher layers. The connection-oriented transmission methods which provide timing relation between sending and receiving AAL service users, are described in ITU-T Recommendation 1.363.1 8, clause 2. These methods form the AAL type 1. They check the validity of the cell sequ
20、ence count, transmit and utilize time stamp information for source clock recovery at the receiver as a user option, optionally correct data by using Forward Error Correction (FEC) and offer utilities to transfer structured data. Subtypes are defined for “circuit transport“, “video signal transport“
21、and “voice-band signal transport“. Page 7 LETS 300 353: October 1998 1 Scope As ITU-T Recommendation 1.363.1 8 contains options and describes methods which can be used in different combinations, this Interim European Telecommunication Standard (LETS) minimizes the options and methods and describes a
22、 subset of the Asynchronous Transfer Mode (ATM) Adaptation Layer (AAL) type 1 to be used in Europe. This LETS describes the interactions between the AAL and the next higher layer, and the AAL and the ATM layer, as well as AAL peer-to-peer operations. 2 Normative references This LETS incorporates by
23、dated and undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this LETS only when
24、 incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. I 1 ITU-T Recommendation G.702: “Digital hierarchy bit rates“. 31 ITU-T Recommendation G.707: “Network node interface for the synchronous digital hierarchy (SDH)“. ITU-T Re
25、commendation G.711: “Pulse code modulation (PCM) of voice frequencies“. ITU-T Recommendation G.823: “The control of jitter and wander within digital networks which are based on the 2048 kbis hierarchy“. 41 ITU-T Recommendation G.824: “The control of jitter and wander within digital networks which ar
26、e based on the 1544 kbitls hierarchy“. 161 ITU-T Recommendation 1.231 : “Circuit-mode bearer service categories“. 171 ITU-T Recommendation 1.361 (I 993): “B-ISDN ATM layer specification“. 181 ITU-T Recommendation 1.363.1 (1 996): “B-ISDN ATM Adaptation: Type 1 AAL“. 191 11 31 ITU-T Recommendation J.
27、82 (1 995): “Transport of MPEG-2 constant bit rate television signals in B-ISDN“. ITU-T Recommendation H.31 O (1 995): “Broadband audiovisual communication systems and terminals“. ITU-T Recommendation H.320 (1 993): “Narrow-band visual telephone systems and terminal equipment“. ITU-T Recommendation
28、H.321: “Adaptation of H.320 visual telephone terminals to B-ISDN environments“. ITU-T Recommendation H.221 (1995): “Frame structure for a 64 to 1 920 kbis channel in audiovisual teleservices“. 3 Definitions and abbreviations 3.1 Definitions For the purposes of this LETS, the following definitions ap
29、ply: Previous page is blank STDOETSI I-ETS 300 353-ENGL 1998 W 3400855 034170b 930 Page 8 I-ETC 300 353: October 1998 ATM Adaptation Layer (AAL): The AAL uses the ATM layer service and includes multiple protocols to fit the need of the different AAL service users. In AAL type 1 source timing recover
30、y is provided at the receiver. Convergence Sublayer Indication (CSI): The CSI is a part of the Protocol Control Information (PCI) in the SAR sublayer; it indicates a special event in the sending Convergence Sublayer (CS) entity in combination with the Sequence Count (SC) and depending on the AAL sub
31、type used: it supports source clock timing recovery using the SRTS method, data structure indication using the SDT method and bit error and cell loss recovery using Forward Error Correction (FEC). Forward Error Correction (FEC): The FEC method is adapted to the error conditions at the ATM layer. non
32、-P format: Format of the SAR-PDU (Protocol Data Unit) payload, which does not carry a pointer of the SDT method. P format: Format of the SAR-PDU payload which carries a pointer of the SDT method. Residual Time Stamp (RTS): The SRTS method uses the RTS value to measure and convey information about th
33、e frequency differences between a common reference clock (derived from the network) and a service clock. The same derived network clock is assumed to be available at both the transmitter and the receiver. Sequence Count (SC): This 3-bit field counts the SAR-PDUs from O to 7 (modulo 8). Sequence Numb
34、er (SN): The SN field consists of the I-bit indication called CSI and a 3-bit SC in the SAR-PDUS. Sequence Number Protection (SNP): The SNP protects the SN by Cyclic Redundancy Check (CRC) and parity check. Structured Data Transfer (SDT): The SDT method supports the transmission of structured data (
35、blocks of user data organized in octets) by using a pointer to the start of a block. Synchronous Residual Time Stamp (method) (SRTS): This method uses the RTS values (transferred peer-to-peer) to recover the source service clock at the receiver side. 3.2 Abbreviations For the purposes of this I-ETS,
36、 the following abbreviations apply: AAL ATM CRC cs CSI FEC PCI PDU PICS RPOA RTS SAP SAR sc SDH SDL SDT SDU SN SNP SRTS STM-I ATM Adaptation Layer Asynchronous Transfer Mode Cyclic Redundancy Check Convergence Sublayer Convergence Sublayer Indication Forward Error Correction Protocol Control Informa
37、tion Protocol Data Unit Protocol Implementation Conformance Statement Recognized Private Operating Agency Residual Time Stamp Service Access Point Segmentation And Reassembly (sublayer) Sequence Count Synchronous Digital Hierarchy Specification and Description Language Structured Data Transfer Servi
38、ce Data Unit Sequence Number Sequence Number Protection Synchronous Residual Time Stamp (method) Synchronous Transport Module - 1 Page 9 I-ETS 300 353: October 1998 4 AALtypel The AAL enhances the service provided by the ATM layer to support functions required by the next higher layer. The AAL perfo
39、rms functions required by the user, control and management planes and supports the mapping between the ATM layer and the next higher layer. The functions performed in the AAL depend upon the higher layer requirements. The AAL supports multiple protocols to fit the needs of the different AAL service
40、users. The service provided by the AAL type 1 protocol to the higher layer and the functions performed are specified in this I-ETS. Details of the data unit naming convention used in this I-ETS can be found in annex A. This I-ETS describes the interactions between the AAL and the next higher layer,
41、and the AAL and the ATM layer, as well as AAL peer-to-peer operations. Different combinations of SAR sublayers and CS provide different Service Access Points (SAPS) to the layer above the AAL. 4.1 Service primitives provided by AAL type 1 The layer service capabilities provided by AAL type 1 to the
42、AAL user are: - transfer of service data units with a constant source bit rate and the delivery of them with the same bit rate; - - transfer of timing information between source and destination; transfer of structure information between source and destination; - indication of lost or errored informa
43、tion which is not recovered by AAL type 1, if needed. At the AAL-SAP, the following primitives are used between the AAL type 1 and the AAL user. They represent an abstract model of the interface and they are not intended to constrain implementations: - from an AAL user to the AAL, AAL-UN ITDATA-REQU
44、EST; - from the AAL to an AAL user, AAL-UNITDATA-INDICATION. An AAL-UNITDATA-REQUEST primitive at the local AAL-SAP results in an AAL-UNITDATA-INDICATION primitive at its peer AAL-SAP. 4.1.1 AAL-UNITDATA-REQUEST AAL-UNITDATA-REQU EST: - (DATA mandatory; - STRUCTURE optional). The AAL-UNITDATA-REQUES
45、T primitive requests the transfer of the AAL-SDU, .e. contents of the DATA parameter, from the local AAL entity to its peer entity. The length of the AAL-SDU is constant and the time interval between two consecutive primitives is constant. These two constants depend upon the specific AAL service pro
46、vided to the AAL user. 4.1.2 AAL-UNITDATA-INDICATION AAL-UNITDATA-INDICATION: - (DATA mandatory; - STRUCTURE optional; STDmETSI I-ETS 300 353-ENGL 1778 II 3400855 0343708 703 Page 10 I-ETS 300 353: October 1998 - STATUS optional). An AAL user is notified by the AAL that the AAL-SDU from its peer is
47、available (.e. via the contents of the DATA parameter). The length of the AAL-SDU shall be constant and the time interval between two consecutive primitives shall be constant. These two constants depend upon the specific AAL service provided to the AAL user. 4.1.3 Definition of parameters 4.1.3.1 DA
48、TA parameter (Mandatory). The DATA parameter carnes the AAL-SDU to be sent or delivered. Its size depends on the specific AAL service used. 4.1.3.2 STRUCTURE parameter (Optional use). The STRUCTURE parameter can be used when the user data stream to be transferred to the peer AAL entity is organized
49、into groups of octets. The length of the structured block is fixed for each instance of the AAL service. The length is an integer multiple of one octet. An example of the use of this parameter is to support circuit mode bearer services of the 64 kbitls based ISDN. If the optional parameter is present, the two values of the STRUCTURE parameter are: - START;and - CONTINUATION. The value START is used when the DATA is the first part of a structured block which can be composed of consecutive DATA. In other cases, the STRUCTURE parameter is set to CONTINUATION. The use
