1、ITU-T RECMN*Q.700 73 m 48b2593 0584937 667 m INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU SPECIFICATIONS OF SIGNALLING SYSTEM No. 7 Q.700 (03/93) INTRODUCTION TO CCITT SIGNALLING SYSTEM No. 7 ITU=T Recommendation Q.700 (Previously “CCITT Recommendation”
2、) _ ITU-T RECMN*d.700 93 m 4862591 O584920 389 m FOREWORD The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the International Telecom- munication Union. The llJ-T is responsible for studying technical, operating and iariff questions and issuing Recommendations on them
3、with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, established the topics for study by the 1”-J-T Study Groups which, in their turn, produce Recommendations on these topics. IT-T Recommend
4、ation Q.700 was revised by the IT-T Study Group XI (1988-1993) and was approved by the WTSC (Helsinki, March 1-12,1993). NOTES 1 As a consequence of a reform process within the International Telecommunication Union (ITU), the CCITT ceased to exist as of 28 February 1993. In its place, the Telecommun
5、ication Standardization Sector (ITU-T) was created as of 1 March 1993. Similarly, in this reform process, the CCIR and the IFRB have been replaced by the Radiocommunication Sector. In order not to delay publication of this Recommendation, no change has been made in the text to references containing
6、the acronyms “CCIT, CCIR or LF” or their associated entities such as Plenary Assembly, Secretanat, etc. Future editions of this Recommendation will contain the proper terminology related to the new ITU structure. 2 telecommunication administration and a recognized operating agency. In this Recommend
7、ation, the expression Administration” is used for conciseness to indicate both a O ITU 1994 All rights reserved. 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 t
8、he ITU. ITU-T RECMNtQ.700 93 m 4862593 0584923 235 m 1 2 5 10 CONTENTS Page General . 1 1.1 Objectives and fields of application 1 1.2 General characteristics 2 1.3 Components of SS No. 7 2 1.4 Description techniques in the Q.7xx-Series Recommendations . 3 SS No. 7 signalling network . 2.1 Basic con
9、cepts 3 2.2 Signaihg network compon ents., 3 2.3 Signailmg point modes . 4 2.4 Signalling routes . 5 2.5 Signalling network stnicture . 5 3 SS No. 7 functional blocks . 6 3.1 Basic functional division 6 3.2 SS No. 7 architecture 7 OS1 layering and SS No. 7 . 9 4.1 OS1 Layering 9 4.2 Relationship bet
10、ween SS No. 7 layering and the OS1 model . 10 4.3 Primitive Interfaces between SS No. 7 Functions 10 Addressing . 11 5.1 Signalling message structure 12 5.2 MTP addressing 12 5.4 User Part addressing . 15 5.5 Labelling . 16 5.3 SCCP addressing 15 Operations administration and maintenance 16 6.1 Mana
11、gement . 16 6.2 Maintenance and testing . 16 6.3 SS No. 7 measurements 17 Signalling system performance 17 7.1 Hypothetical Signalling Reference Connection (HSRC) 17 7.2 MTP 17 7.3 SCCP 17 7.4 18 7.5 IS 18 Flow control . 18 8.2 Signailing node (congestion) flow control 18 Compatibility mechanisms an
12、d rules in SS No. 7 18 9.1 Background . 18 9.2 Evolutionary requiremen 19 9.3 Forward and backward compatibility . 19 9.4 Compatibility rules for SS No. 7 19 Glossary . 20 8.1 Signalling network flow control. 18 Recommendation 4.70 (03D3) 1 ITU-T RECMN*Q*700 93 W 4862573 0584922 353 Recommendation Q
13、.700 INTRODUCTION TO CCITT SIGNALLING SYSTEM No. 7 (Melbourne 1988: mod8ed at Helsinki 1993) 1 General This Recommendation provides an overview of the Signalling System by describing the various functional elements ofCCIT Signalling System No. 7 (SS No. 7) and the relationship between these function
14、al elements. This Recommendation provides a general description of functions and capabilities of the Message Transfer Part (MTP), Signailing Connection Control Part (SCCP), Telephone User Part, ISDN User Part (ISUP), Transaction Capabilities (TC), and the Operations, Maintenance and Administration P
15、art (OMAP) which are covered elsewhere in the Q.7xx-Series Recommendations. ms includes Recommendations Q.700 to Q.787.) However, in the case of contradiction between a particular specification and Recommendation Q.700, the particular specification shall apply. The SS No. 7 ISDN supplementary servic
16、es are described in the Q.73-Series Recommendations. In addition to these functions in the SS No. 7 signalling system, the Q.7xx Series Recommendations describes the SS No. 7 network structure, and also specifies the tests and measurements applicable to SS No. 7. This Recommendation also contains in
17、formation about other aspects such as SS No. 7 architecture, flow control and general compatibility rule which are not specified in separate Recommendations, and are applicable to the overall scope of SS No. 7. Recommendation Q.1400 also contains information about architecture and compatibility. The
18、 remainder of this Recommendation describes: - clause 2 Signalling network concepts components and modes; - clause 3: - clause 4 - clause 5 Node, application entity and user part addressing; - clause 6 - clause 7: - clause 8: - clause 9: - clause 10 A cross-reference to a glossary of terms. The func
19、tional blocks within SS No. 7 and the services provided by them; SS No. 7 protocol layering and its relationship to OS1 modelling; Operations, administration and maintenance aspects of SS No. 7; Performance aspects of the functional blocks within SS No. 7; Flow control for both the signalling networ
20、k and within nodes; Rules for evolving SS No. 7 protocols while preserving Compatibility with earlier versions; 1.1 The overaii objective of SS No. 7 is to provide an internationally standardized general purpose common channel signaiiiig (CCS) system: optimized for operation in digital telecommunica
21、tions networks in conjunction with stored program controlled exchanges; that can meet present and future requirements of information transfer for inter-processor transactions within telecommunications networks for call control, remote control, and management and maintenance signalling; that provides
22、 a reliable means for transfer of information in correct sequence and without loss or duplication. Objectives and fields of application - - - The signailing system meets requirements of call control signalling for telecommunication services such as the telephone, ISDN and circuit switched data trans
23、mission services. It can also be used as a reliable transport system for other types of information ransfer between exchanges and specialized centres in telecommunications networks (e.g. for Recommendation 4.700 (03/93) 1 ITU-T RECMN*Q.700 93 W 48b259L 0584923 098 W management and maintenance purpos
24、es). The system is thus applicable for multipurpose uses in networks that are dedicated for particular services and in multiservices networks. The signailing system is intended to be applicable in international and national networks. The scope of SS No. 7 encompasses both circuit related and non-cir
25、cuit related signailing. Examples of applications supported by SS No. 7 are: - PSTN; - ISDN - - Interaction with Network Databases, Service Control Points for service control; Mobiles (Public Land Mobile Network); - Operations Administration and Maintenance of Networks. The signalling system is opti
26、mized for operation over 64 kbit/s digital channels. It is also suitable for operation over analogue channels and at lower speeds. The system is suitable for use on point-to-point terrestrial and satellite links. It does not include the special features required for use in point-to-multipoint operat
27、ion but can, if required, be extended to cover such an application. 1.2 General characteristics Common channel signalling is a signalling method in which a single channel conveys, by means of labelied messages, signalling information relating to, for example, a multiplicity of circuits, or other inf
28、ormation such as that used for network management. Common channel signalling can be regarded as a form of data communication that is specialized for various types of signalling and information transfer between processors in telecommunications networks. The signalling system uses signalling links for
29、 transfer of signailing messages between exchanges or other nodes in the telecommunication network served by the system. Arrangements are provided to ensure reliable transfer of signalling information in the presence of transmission disturbances or network failures. These include error detection and
30、 correction on each signalling link. The system is normaily applied with redundancy of signalling links and it includes functions for automatic diversion of signalling traffic to alternative paths in case of link failures. The capacity and reliability for signalling may thus be dimensioned by provis
31、ion of a multiplicity of signalling links according to the requirements of each application. 1.3 Components of SS No. 7 SS No. 7 consists of a number of components or functions which defined in the Q.7xx-Series Recommendations. SS No. 7jnction Recommendations Message Transfer Part (MTP) Q.701-Q.704,
32、 Q.706, Q.707 Telephone User Part (TP) (including some supplementary services) Q.721-Q.725 Supplementary services Q.73 Series Data User Part UP) Q.741 (see Note) ISDN User Part (ISUP) Q.761-Q.764, Q.766 Signalling Connection Control Part (SCCP) Q.711-Q.714, Q.716 Transaction Capabilities (TC) Q.771-
33、Q.775 Operations Maintenance and Administration Part (OMAP) Q.750-Q.755 NOTE - Functions of the DUP are fully specified in Recommendation X.61. 2 Recommendation 4.700 (03D3) ITU-T RECMN*Q.700 93 W 4862573 0584924 T24 W Other Q.7xx-Series Recommendations which describe other aspects of the signalling
34、 system which are not part of the SS No. 7 signalling interfaces are: Title SignaUing Network Siructure Numbering of International Signalling Point Codes Hypothetical signalling reference connection PABX application SS No. 7 Test Specification (General) MTP Level 2 Test Specification MTP Level 3 Tes
35、t Specification TUP Test Specifcation ISP Test Specification ISUP Supplementary Service Test Specification SCCP Test Specification TCAP Test Specification Clause 3 describes the relationship between these components. Recommendations Q.705 Q.708 Q.709 Q.7 10 Q.780 Q.78 1 Q.782 Q.783 Q.784 Q.785 Q.786
36、 Q.787 1.4 The SS No. 7 Recommendation Series defines the signalling system using prose description which is complemented by SDL diagrams and state transition diagrams. Should any conflict arise between the text and the SDL definition, the textual description is taken as definitive. Message sequence
37、 charts or arrow diagrams are used to illustrate examples of signalling procedures, but are not considered definitive. Data description are increasingly using ASN.l method of description. Descdption techniques in the Qdxx-Series Recommendations 2 SS No. 7 signalling network 2.1 Basic concepts A tele
38、communications network served by common channel signalling is composed of a number of switching and processing nodes interconnected by transmission links. To communicate using SS No. 7, each of these nodes requires to implement the necessary “within node” features of SS No. 7 making that node a sign
39、alling point within the SS No. 7 network. In addition, there will be a need to interconnect these signalling points such that SS No. 7 signalling information (data) may be conveyed between tbem. These data links are the signalling links of SS No. 7 signalling network. The combination of signalling p
40、oints and their interconnecting signalling links form the SS No. 7 signalling network. 2.2 Signalling network components 23.1 Signaiing points In specific cases there may be a need to partition the common channel signalling functions at such a (physical) node into logically separate entities from a
41、signalling network point of view; i.e. a given (physical) node may be defined as more than one signailing point. he example is an exchange at the boundary between international and national signalling networks. Any two signalling points, for which the possibility of communication between their corre
42、sponding User Part function exists, are said to have a signalling relation. The correspondmg concept for a given User Part is called a user signalling relation. Recommendation 4.700 (03/93) 3 ITU-T RECMN*Q*700 93 48b259L 0581.1925 960 An example is when two telephone exchanges are directly connected
43、 by a bundle of speech circuits. The exchange of telephone signalling relating to these circuits then constitutes a user signalling relation between the Telephone User Part functions in those exchanges in their role as signalling points. Another example is when administration of customer and routing
44、 data in a telephone exchange is remotely controlled from an operation and maintenance centre by means of communication through a common channel signalling system. Examples of nodes in a signalling network that constitutes signalling points are: - exchanges (switching centres); - service conuol poin
45、ts; - Signalling transfer points; - operation, administration and maintenance centres. AU signalling points in a SS No. 7 network are identified by a unique code known as a point code (Recommen- dation Q.704 refers). 2.2.2 Signailing links The common channel signalling system uses signalling links t
46、o convey the signalling messages between two signalling points. A number of signalling links that directly interconnect two signalling points which are used as a module constitute a signalling link-set. Although a link set typically includes all parallel signalling links, it is possible to use more
47、than one link set in parallel between two signalling points. A group of links within a link set that have identical characteristics (e.g. the same data link bearer rate) is called a link group. Two signalling points that are directly interconnected by a signalling link are, from a signalling network
48、 structure point of view, referred to as adjacent signalling points. Correspondingly, two signalling points that are not directly interconnected are non-adjacent signalling points. 2.2.3 Signailing modes The term “signalling mode” refers to the association between the path taken by a signailing mess
49、age and the signalling relation to which the message refers. In the associated mode of signalling, the messages relating to a particular signalling relation between two adjacent points are conveyed over a link set, directly interconnecting those signalling points. In the non-associated mode of signalling, the messages relating to a particular signalling relation are conveyed over two or more linksets in tandem passing through one or more signalling points other than those which are the origin and the destination of the messages. The quasi-associated mode of sign
