1、 INTERNATIONAL TELECOMMUNICATION UNION Q.920TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Amendment 1(06/2000) SERIES Q: SWITCHING AND SIGNALLING Digital subscriber Signalling System No. 1 Data link layer ISDN user-network interface data link layer General aspects Amendment 1 ITU-T Recommendation
2、Q.920 Amendment 1 (Formerly CCITT Recommendation) ITU-T Q-SERIES RECOMMENDATIONS SWITCHING AND SIGNALLING SIGNALLING IN THE INTERNATIONAL MANUAL SERVICE Q.1Q.3 INTERNATIONAL AUTOMATIC AND SEMI-AUTOMATIC WORKING Q.4Q.59 FUNCTIONS AND INFORMATION FLOWS FOR SERVICES IN THE ISDN Q.60Q.99 CLAUSES APPLICA
3、BLE TO ITU-T STANDARD SYSTEMS Q.100Q.119 SPECIFICATIONS OF SIGNALLING SYSTEMS No. 4 AND No. 5 Q.120Q.249 SPECIFICATIONS OF SIGNALLING SYSTEM No. 6 Q.250Q.309 SPECIFICATIONS OF SIGNALLING SYSTEM R1 Q.310Q.399 SPECIFICATIONS OF SIGNALLING SYSTEM R2 Q.400Q.499 DIGITAL EXCHANGES Q.500Q.599 INTERWORKING
4、OF SIGNALLING SYSTEMS Q.600Q.699 SPECIFICATIONS OF SIGNALLING SYSTEM No. 7 Q.700Q.799 Q3 INTERFACE Q.800Q.849 DIGITAL SUBSCRIBER SIGNALLING SYSTEM No. 1 Q.850Q.999 General Q.850Q.919 Data link layer Q.920Q.929 Network layer Q.930Q.939 User-network management Q.940Q.949 Stage 3 description for supple
5、mentary services using DSS1 Q.950Q.999 PUBLIC LAND MOBILE NETWORK Q.1000Q.1099 INTERWORKING WITH SATELLITE MOBILE SYSTEMS Q.1100Q.1199 INTELLIGENT NETWORK Q.1200Q.1699 SIGNALLING REQUIREMENTS AND PROTOCOLS FOR IMT-2000 Q.1700Q.1799 BROADBAND ISDN Q.2000Q.2999 For further details, please refer to the
6、 list of ITU-T Recommendations. ITU-T Q.920/Amd.1 (06/2000) i ITU-T Recommendation Q.920 ISDN user-network interface data link layer General aspects AMENDMENT 1 Summary This Recommendation describes in general terms the link access procedure on the D-channel, LAPD. Details are provided in ITU-T Q.92
7、1 1. The purpose of LAPD is to convey information between layer 3 entities across the ISDN user-network interface using the D-channel. This Recommendation has been amended in order to add a new Annex A to describe in general terms the link access procedure for use in a symmetrical application betwee
8、n two Private Integrated Network eXchanges (PINXs) at the Q reference point. Source Amendment 1 to ITU-T Recommendation Q.920 was prepared by ITU-T Study Group 11 (1997-2000) and approved under the WTSC Resolution 1 procedure on 15 June 2000. ii ITU-T Q.920/Amd.1 (06/2000) FOREWORD The International
9、 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. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on
10、 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 ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of
11、 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 ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is
12、 used for conciseness to indicate both a telecommunication administration and a recognized operating agency. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. IT
13、U takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual
14、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. Ge3 ITU 2001 All rights reserved. No part of this public
15、ation may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from ITU. ITU-T Q.920/Amd.1 (06/2000) iii CONTENTS Page 1) Clause 1. 1 2) References. 1 3) New Annex A . 1 Annex A Inter-exchange signalling
16、data link layer protocol in Private Integrated Services Networks (PISNs) Overview of the functions of the data link layer for the support of inter-exchange signalling in PISNs and additions to concepts and terminology to accommodate PISN inter-exchange requirements 1 A.1 Overview of the functions an
17、d procedures of the data link layer . 1 A.1.1 General. 1 A.1.2 Overview of data link layer structure 2 A.2 Concepts and terminology 3 A.2.1 General. 3 A.2.2 Data Link Connection Identification (DLCI). 3 A.2.3 Data link states. 3 A.2.4 Service characteristics . 3 ITU-T Q.920/Amd.1 (06/2000) 1 ITU-T R
18、ecommendation Q.920 ISDN user-network interface data link layer General aspects AMENDMENT 1 1) Clause 1 Add the following new final paragraph to clause 1: Annex A of this Recommendation describes in general terms the link access procedure for use in a symmetrical application between two Private Inte
19、grated Network eXchanges (PINXs) at the Q reference point (see ISO/IEC 11579-1 14). 2) References Add a new reference 14 as follows: 14 ISO/IEC 11579-1:1994, Information technology Telecommunications and information exchange between systems Private integrated services network Part 1: Reference confi
20、guration for PISN Exchanges (PINX). 3) New Annex A Insert a new Annex A as follows: ANNEX A Inter-exchange signalling data link layer protocol in Private Integrated Services Networks (PISNs) Overview of the functions of the data link layer for the support of inter-exchange signalling in PISNs and ad
21、ditions to concepts and terminology to accommodate PISN inter-exchange requirements A.1 Overview of the functions and procedures of the data link layer A.1.1 General Clause 3.1 shall apply whereby the data link layer user invokes those functions and procedures of the data link layer which allow two
22、peer-to-peer layer 3 entities to communicate on a single point-to-point data link connection, making use of the acknowledged information transfer service. For the acknowledged information transfer, the properties defined in 3.3 apply. Figure A.1 shows point-to-point information transfer in the case
23、of two interconnected PINXs and depicts the point-to-point nature of both layers 1 and 2. 2 ITU-T Q.920/Amd.1 (06/2000) T11106700-00* *PINX PINXL3L2L1L3L2L1SAPxMaster sideSAPxSlave sideData link connectionPhysical connectionFigure A.1/Q.920 Point-to-point data link connection A.1.2 Overview of data
24、link layer structure A.1.2.1 Data link procedure Clause 5.1 shall apply. A.1.2.2 Multiplex procedure Clause 5.2 shall apply. A.1.2.3 Structure of the data link procedure and management function The functional model of the data link procedure (including management functions) is shown in Figure A.2. T
25、his figure is shown for informative purposes only and is not intended to constrain implementations. The Layer Management Entity (LME) provides for the management of resources that have a layer wide impact. The Connection Management Entity (CME) provides for the management of resources that have an i
26、mpact on individual connections. T11106710-00*PINX PINXCME CMELME LMELayer 3 Layer 3Layer 2 Layer 2Layer management Layer managementData linkentityData linkentityLayer 1Layer 1MediumSystemmanagementSystemmanagementFigure A.2/Q.920 Functional model of data link layer structure ITU-T Q.920/Amd.1 (06/2
27、000) 3 A.2 Concepts and terminology A.2.1 General The concepts and terminology described in clause 2 shall apply with the following addition: all data link entities at one end of a particular inter-PINX signalling channel shall be designated as either “master“ or “slave“; PINXs conforming to this an
28、nex shall be capable of providing both master and slave functions on different inter-PINX signalling channels. Therefore, the configuration shown in Figure A.3 may exist. T11106720-00PINX BPINX CmmmsssPINX AInter-PINX signalling channelsFigure A.3/Q.920 Example of PINX configuration The assignment o
29、f the master or slave shall occur on initialization (or reinitialization) of the inter-PINX signalling channels and the designation shall be decided at network configuration time. The assignment of master/slave relationships at the data link layer shall not preclude different master/slave relationsh
30、ips at other layers in the ISDN protocol reference model. A.2.2 Data Link Connection Identification (DLCI) Clause 3.4.1 shall apply with the following exception: Automatic TEI-assignment procedures shall not be used by equipment conforming to this annex. A.2.3 Data link states Clause 3.4.2 shall app
31、ly. A.2.4 Service characteristics A.2.4.1 General Clause 4.1 shall apply. A.2.4.2 Service provided to layer 3 Clause 4.2 and its clauses shall apply whereby layer 3 invokes the acknowledged information transfer service only. A.2.4.3 Services provided to layer management In equipment conforming to th
32、is annex, all layer management functions shall be performed locally. Therefore, no links for peer-to-peer management information are required. 4 ITU-T Q.920/Amd.1 (06/2000) A.2.4.4 Administrative services The procedures for assignment, checking and removal of TEIs referenced in 4.1 shall apply inter
33、nally, but not on a peer-to-peer basis, to PINXs conforming to this annex. The following primitives are defined: a) MDL-ASSIGN request The primitive is used by the Layer Management Entity (LME) to deliver to the Data Link Entity (DLE) the TEI value that is to be used for communication. b) MDL-ERROR
34、indication/response These primitives are used to report error situations between layer management and the data link layer entities. A.2.4.5 Services required from the physical layer Clause 4.6 shall apply. Geneva, 2001 SERIES OF ITU-T RECOMMENDATIONS Series A Organization of the work of ITU-T Series
35、 B Means of expression: definitions, symbols, classification Series C General telecommunication statistics Series D General tariff principles Series E Overall network operation, telephone service, service operation and human factors Series F Non-telephone telecommunication services Series G Transmis
36、sion systems and media, digital systems and networks Series H Audiovisual and multimedia systems Series I Integrated services digital network Series J Transmission of television, sound programme and other multimedia signals Series K Protection against interference Series L Construction, installation
37、 and protection of cables and other elements of outside plant Series M TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits Series N Maintenance: international sound programme and television transmission circuits Series O Spec
38、ifications of measuring equipment Series P Telephone transmission quality, telephone installations, local line networks Series Q Switching and signalling Series R Telegraph transmission Series S Telegraph services terminal equipment Series T Terminals for telematic services Series U Telegraph switching Series V Data communication over the telephone network Series X Data networks and open system communications Series Y Global information infrastructure and Internet protocol aspects Series Z Languages and general software aspects for telecommunication systems
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