1、 I n t e r n a t i o n a l T e l e c o m m u n i c a t i o n U n i o n ITU-T I.570 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (01/2018) SERIES I: INTEGRATED SERVICES DIGITAL NETWORK Internetwork interfaces Public/private ISDN interworking Recommendation ITU-T I.570 ITU-T I-SERIES RECOMMENDATION
2、S INTEGRATED SERVICES DIGITAL NETWORK GENERAL STRUCTURE Terminology I.110I.119 Description of ISDNs I.120I.129 General modelling methods I.130I.139 Telecommunication network and service attributes I.140I.149 General description of asynchronous transfer mode I.150I.199 SERVICE CAPABILITIES Scope I.20
3、0I.209 General aspects of services in ISDN I.210I.219 Common aspects of services in the ISDN I.220I.229 Bearer services supported by an ISDN I.230I.239 Teleservices supported by an ISDN I.240I.249 Supplementary services in ISDN I.250I.259 OVERALL NETWORK ASPECTS AND FUNCTIONS Network functional prin
4、ciples I.310I.319 Reference models I.320I.329 Numbering, addressing and routing I.330I.339 Connection types I.340I.349 Performance objectives I.350I.359 Protocol layer requirements I.360I.369 General network requirements and functions I.370I.399 ISDN USER-NETWORK INTERFACES Application of I-series R
5、ecommendations to ISDN user-network interfaces I.410I.429 Layer 1 Recommendations I.430I.439 Layer 2 Recommendations I.440I.449 Layer 3 Recommendations I.450I.459 Multiplexing, rate adaption and support of existing interfaces I.460I.469 Aspects of ISDN affecting terminal requirements I.470I.489 INTE
6、RNETWORK INTERFACES I.500I.599 MAINTENANCE PRINCIPLES I.600I.699 B-ISDN EQUIPMENT ASPECTS ATM equipment I.730I.739 Transport functions I.740I.749 Management of ATM equipment I.750I.759 Multiplexing aspects I.760I.769 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T
7、I.570 (01/2018) i Recommendation ITU-T I.570 Public/private ISDN interworking Summary Recommendation ITU-T I.570 focuses on the aspect of private networks connection to a public integrated services digital network (ISDN) with ISDN user part (ISUP). This Recommendation presents public/private ISDN in
8、terworking reference configurations, scenarios for public/private ISDN interworking, service interworking and interworking requirements at point of interconnection. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T I.570 1993-03-12 XVIII 11.1002/1000/1321 2.0 ITU-T I.570 2018-
9、01-13 13 11.1002/1000/13442 Keywords Interworking, private, public. * To access the Recommendation, type the URL http:/handle.itu.int/ in the address field of your web browser, followed by the Recommendations unique ID. For example, http:/handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T I.570 (01
10、/2018) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible f
11、or studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T stu
12、dy groups which, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis
13、 with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory p
14、rovisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use
15、of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTSITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no po
16、sition 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 property, pro
17、tected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2018 All rights reserved. No part
18、 of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T I.570 (01/2018) iii Table of Contents Page 1 Scope . 1 2 References . 1 3 Definitions 2 3.1 Terms defined elsewhere 2 3.2 Terms defined in this Recommendation . 2 4 Abbreviations
19、and acronyms 2 5 Conventions 2 6 Reference configurations 3 7 Scenarios for public/private ISDN interworking 4 8 Service interworking . 5 8.1 Introduction 5 8.2 Service provision concept . 6 8.3 Public/private ISDN configurations . 7 8.4 Interworking requirements . 8 9 Interworking requirements at p
20、oint of interconnection 10 Bibliography. 11 Rec. ITU-T I.570 (01/2018) 1 Recommendation ITU-T I.570 Public/private ISDN interworking 1 Scope Recognizing that the ITU-T Recommendations on integrated services digital networks (ISDNs) apply to public ISDNs and may also apply to private ISDNs, there is
21、a need to ensure smooth service interworking across public and private ISDNs such that the services provided are transparent to the user across the public and private network components. This Recommendation aims to provide general principles and guidelines for the interworking of public and private
22、ISDNs. The following objectives are envisaged in the development of Recommendations on public/private ISDN interworking: 1) The provision of common compatible functionality to provide common ISDN services; 2) The provision of end-to-end (TE1-type) ISDN terminal connectivity as well as terminal inter
23、changeability; 3) A common overall ISDN transmission plan. 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
24、Recommendations and other references are subject to revision; 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 regu
25、larly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T E.164 Recommendation ITU-T E.164 (2010), The international public telecommunication numbering plan. ITU-T E.166 Recommendation ITU-T E.166/X.122
26、(1998), Numbering plan interworking for the E.164 and X.121 numbering plans. ITU-T I.112 Recommendation ITU-T I.112 (1993), Vocabulary of terms for ISDNs. ITU-T I.210 Recommendation ITU-T I.210 (1993), Principles of telecommunication services supported by an ISDN and the means to describe them. ITU-
27、T I.230 Recommendation ITU-T I.230 (1988), Definition of bearer service categories. ITU-T I.240 Recommendation ITU-T I.240 (1988), Definition of teleservices. ITU-T I.411 Recommendation ITU-T I.411 (1993), ISDN user-network interfaces Reference configurations. ITU-T I.412 Recommendation ITU-T I.412
28、(1988), ISDN user-network interfaces Interface structures and access capabilities. ITU-T I.510 Recommendation ITU-T I.510 (1993), Definitions and general principles for ISDN interworking. ITU-T I.520 Recommendation ITU-T I.520 (1993), General arrangements for network interworking between ISDNs. 2 Re
29、c. ITU-T I.570 (01/2018) ITU-T Q.764 Recommendation ITU-T Q.764 (1999), Signalling System No.7 ISDN User Part signalling procedures. ITU-T Q.931 Recommendation ITU-T Q.931 (1998), ISDN user-network interface layer 3 specification for basic call control. ITU-T Q.1902.4 Recommendation ITU-T Q.1902.4 (
30、2001), Bearer independent call control protocol (Capability Set 2): Basic call procedures. ITU-T X.75 Recommendation ITU-T X.75 (1996), Packet-switched signalling system between public networks providing data transmission services. 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses t
31、he following terms defined elsewhere: 3.1.1 customer equipment: ITU-T I.112, item 430. 3.1.2 customer network: ITU-T I.411 3.1.3 network: ITU-T I.112, item 305. 3.1.4 user: ITU-T I.112, item 401. 3.2 Terms defined in this Recommendation This Recommendation defines the following terms: 3.2.1 public n
32、etwork: A network which provides services to the general public. 3.2.2 private network: A network which provides services to a specific set of users only. 3.2.3 mixed public/private ISDN: An overall ISDN which consists of any concatenation of public and private networks. The user perspective of the
33、services offered by a mixed public/private ISDN is common and consistent across the public and private network components of the mixed network. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: ISDN Integrated Services Digital Network ISPBX Integrated Se
34、rvices Private Branch Exchange ISUP ISDN User Part IWF Interworking Function LAPD Link Access Procedure D-channel SS7 Signalling System No. 7 TE Terminal Equipment VPN Virtual Private Network 5 Conventions None. Rec. ITU-T I.570 (01/2018) 3 6 Reference configurations The functional groups and refere
35、nce configurations for the customer network are described in ITU-T I.411, while the interface structures to be used at reference points S and T are described in ITU-T I.412. Figure 1 illustrates this overall division of functions involved in a communication across the ISDN. NOTE 1 The functional gro
36、up customer network is described in ITU-T I.411. NOTE 2 If the customer network is null (i.e., null NT2) the ISDN connection can be considered to end at coincident S and T reference points. NOTE 3 If the customer network is an ISPBX-based network, providing the same ISDN connection types according t
37、o b-ITU-T I.430 as the public ISDN does, the ISDN connection ends at the S reference point as shown in Figure 2. Figure 1 General ISDN reference configuration NOTE 1 This reference configuration applies to the case where the customer network consists only of ISPBXs. The case in which “IS-CENTREXs“ a
38、re included is for further study. NOTE 2 Other configurations are possible where the call is asymmetrical, or terminates in or involves high layer functions. NOTE 3 The terms “customer equipment“ and “public ISDN“ do not presuppose a particular regulatory situation in any country and are used purely
39、 for technical reasons. The connection type concept is defined in b-ITU-T I.340. Figure 2 Overall ISDN reference configuration for a mixed ISPBX/public ISDN scenario Public/private ISDN interconnection at Nx reference point will be regarded as ISDN-to-ISDN interworking. The definitions and general p
40、rinciples of ISDN interworking are described in ITU-T I.510. Figure 3 shows the general reference configuration of the private ISDN connecting to the public ISDN at the Nx reference point. Figure 3 General reference configuration of the private ISDN connecting to the public ISDN at the Nx reference
41、point scenario 4 Rec. ITU-T I.570 (01/2018) Figure 4 shows overall reference configuration for a mixed ISPBX/private ISDN connecting to the public ISDN at the Nx reference point. S reference point is provided to the TE by ISPBX/private ISDN. Figure 4 Overall reference configuration for a mixed ISPBX
42、/private ISDN connect to the public ISDN at the Nx reference point scenario 7 Scenarios for public/private ISDN interworking In the overlay scenario, the connection, which is established through the public ISDN, is treated as a private ISDN-to-private ISDN link (link B in Figure 5). Signalling and/o
43、r user information which is carried on link B is transparent to the public ISDN. In this case, the services available to a terminal equipment (TE) are those offered by the private ISDN, as if they were provided via link A. Figure 5 Overlay scenario For the concatenated case (see Figure 6), interwork
44、ing is required at the user-network access of the public ISDN, i.e., at links 1 and 3. In this case, the services provided to a TE are realized by the cooperation of functions and capabilities provided by both the public and private network. Figure 6 Concatenation scenario Rec. ITU-T I.570 (01/2018)
45、 5 Figure 7 shows a concatenated case where the private ISDN interworks with the public ISDN at the Nx reference point, i.e., at link 1 and link 3. In this case, the services provided to a TE are realized by the private network. The private and public network are interworked at Nx reference point wh
46、ere Signalling System No. 7 (SS7) is used to carry the information handled at the interworking function (IWF). Figure 7 Concatenation scenario for interworking with ISUP/BICC The functionality of an overlay scenario may be achieved by upgrading a concatenation scenario by means of virtual private ne
47、twork (VPN) features. Virtual private ISDNs may support features such as uniform numbering plan, specialized routing, account codes and extension dialling. Also the efficiency of user information transfer may be improved e.g., by the provision of A-law/-law conversion, echo cancellation, etc. The VP
48、N concept and its relationship to the overlay and concatenation scenarios require further study. NOTE The overlay scenario (Figure 5) is not currently addressed in clauses 8 and 9. 8 Service interworking 8.1 Introduction The following public/private ISDN interworking principles are identified: i) In
49、 a mixed public/private ISDN, the stage 1 service descriptions should provide views of the service for both the S and T reference points and these views may be different. Where S and T reference points are coincident, one view of the service applies. Additional requirements for the service definition at the T reference point, if any, should be separately identified. ii) For each service, several scenarios may be possible for the actual physical location of logical f
