1、INTERNATIONAL TELECOMMUNICATION UNION ITU=T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU 1.762 SERIES I: INTEGRATED SERVICES DIGITAL NETWORK B-ISDN equipment aspects - Multiplexing aspects (03/2 000) ATM over fractional physical links ITU-T Recommendation 1.762 (Formerly CCITT Recommendation) STD
2、.ITU-T RECIIN 1.7bZ-ENGL 2000 4Bb259L Ob89054 T39 W ITU-T I-SERIES RECOMMENDATIONS INTEGRATED SERVICES DIGITAL NETWORK GENERAL STRUCTURE Terminology Description of ISDNs General modelling methods Telecommunication network and service attributes General description of asynchronous transfer mode Scope
3、 General aspects of services in ISDN Common aspects of services in the ISDN Bearer services supported by an ISDN TeleseMces supported by an ISDN Supplementary services in ISDN Network functional principles Reference models Numbering, addressing and routing Connection types Performance objectives Pro
4、tocol layer requirements General network requirements and functions Application of I-series Recommendations to ISDN user-network interfaces Layer 1 Recommendations Layer 2 Recommendations Layer 3 Recommendations Multiplexing, rate adaption and support of existing interfaces Aspects of ISDN affecting
5、 terminal requirements SERVICE CAPABILITIES OVERALL NETWORK ASPECTS AND FUNCTIONS ISDN USER-NETWORK INTERFACES INTERNETWORK INTERFACES MAINTENANCE PRINCIPLES B-ISDN EQUIPMENT ASPECTS ATM equipment Transport functions I. 1 10-1.1 19 I. 120-1.129 1.130-1.139 I. 140-1.149 1.1.50-1.199 I. 200-1.209 1.2
6、10-1.2 19 1.220-1.229 1.230-1.239 1.240-1.249 1.250-1.299 1.310-1.319 1.320-1.329 1.330-1.339 1.340-1.349 1.350-1.359 1.360-1.369 1.370-1.399 1.420-1.429 1.430-1.439 1.440-1.449 1.450-1.459 1.460-1.469 1.470-1.499 1.500-1.599 1.600-1.699 1.730-1.739 1.740-1.749 Manaeement of ATM eouinment 1.750-1.75
7、9 For further details, please refer to the list of ITU-TRecommendations. STD-ITU-T RECMN 1.762-ENGL 2000 48b257L 0687055 975 ITU-T Recommendation 1.762 ATM over fractional physical links Summary This ITU-T Recommendation specifies the requirements on how to map ATM on a “circuit-mode connection“ sup
8、porting unrestricted information transfer rates at integer multiples of 64 kbit/s up to the maximum rate of the interface. The physical interface may typically be DS1 or El (or any other physical interface). The specification shall apply for any N * 64 kbit/s rate up to 1920 kbit/s (N = 30) and be i
9、ndependent of type of interface (UNI or “1). Source ITU-T Recommendation 1.762 was prepared by ITU-T Study Group 13 (1997-2000) and approved under the WTSC Resolution 1 procedure on 10 March 2000. Keywords ATM, Cell mapping, “I, Physical interface, UNI. STD.ITU-T RECMN 1-7bZ-ENGL 2000 = 4862593 Ob89
10、05b 801 m FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. IT-T is responsible for studying technical, operating and tariff quest
11、ions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the IT-T study groups which, in turn, produce Recommendation
12、s on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSC Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with IS0 and IEC. NOTE In this Recommendation,
13、the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. INTELLECTUAL PROPERTY RIGHTS IT draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claime
14、d Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by IT members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not
15、received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. o ITU 2001 All rights re
16、served. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. 1 2 3 4 Scope References Abbreviations . Detailed requirements . Page 1 1 2 2 ITU-T Recommendatio
17、n 1.762 ATM over fractional physical links 1 Scope This ITU-T Recommendation specifies the requirements on how to map ATM on a “circuit-mode connection“ supporting unrestricted information transfer rates at integer multiples of 64 kbit/s up to the maximum rate of the interface (ITU-T Recommendation
18、1.231.10 i). The physical interface may typically be DS1 or EI (or any other physical interface). The specification shall apply for any N * 64 kbit/s rate up to 1920 kbit/s (N = 30) and be independent of type of interface (UNI or “1). Figure 1 shows the physical layer functionality of ATM when mappe
19、d on a circuit bearer. ATM Cell Stream Cell rate decoupling HEC generatiodverification Cell delineation (1.432) Cell mapping N * 64 kbis Circuit Bearer Frame handling I PMD (e.g. G.703) T1317720-01 I Physical link Figure 1A.762 - Physical layer functions for transfer rates at integer multiples of 64
20、 kbis Observe that the mechanism for how to map ATM on a circuit bearer is not different from the general mechanism described in earlier specifications, e.g. in af-phy-0064.000, “El Physical Interface Specification“ 2 and in ITU-T Recommendation G.804, “ATM Cell Mapping into Plesiochronous Digital H
21、ierarchy“ 4. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subje
22、ct to revision; all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. i CCITT Recommendation 1.
23、23 1.10 (1 992), Circuit-mode Multiple-rate Unrestricted 8 kHz Structured Bearer Service Category. 2 ATM Fom af-phy-0064.000 (1996), El Physical Interface Speczfication. STD-ITU-T RECMN I.762-ENGL ZOO0 D 4862591 0689057 520 3 4 51 61 ITU-T Recommendation G.703 (1 998), Physicalelectrical characteris
24、tics of hierarchical digital interfaces. ITU-T Recommendation G.804 (1998), ATM Cell Mapping into PZesiochronous Digital Hierarchy (PDH). ITU-T Recommendation 1.432.1 (1 999), B-ISDN user-network interface - Physical layer speczjca tion: Gen eral characteristics. ATM Forum af-phy-0 130.000 (1 999),
25、A TM on Fractional EI/TI . 3 Abbreviations This ITU-T Recommendation uses the following abbreviations: HEC Header Error Control ISDN Integrated Services Digital Network NNI Network-Node Interface UNI User Network Interface 4 Detailed requirements The detailed requirements on how to map ATM on a fractional physical link shall be in accordance with ATM Forum Document af-phy-0130.000, “ATM on Fractional EI/TItt, September 1999 6.
