1、STD-ITU-T RECMN 1.525-ENGL 199b II 48b259L Ob359Lb LT3 D INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU SERIES 1: INTEGRATED SERVICES DIGITAL NETWORK Internetwork interfaces 1.525 (08/96) Interworking between networks operating at bit rates less than 64 k
2、bit/s with 64 kbis-based ISDN and B-ISDN TU-T Recommendation 1.525 (Previously CCITT Recommendation) - - STD-ITU-T RECMN 1.525-ENGL L99b 48b2591 Ub359L7 03T ITU-T I-SERIES RECOMMENDATIONS INTEGRATED SERVICES DIGITAL NETWORK GENERAL STRUCTURE Terminology Description of ISDNs General modelling methods
3、 Telecommunication network and service attributes General description of asynchronous transfer mode Scope General aspects of services in ISDN Common aspects of services in the ISDN Bearer services supported by an ISDN Teleservices supported by an ISDN Supplementary services in ISDN Network functiona
4、l principles Reference models Numbering, addressing and routing Connection types Performance objectives Protocol layer requirements General network requirements and functions Application of I-series Recommendations to ISDN user-network interfaces Layer I Recommendations Layer 2 Recommendations Layer
5、 3 Recommendations Multiplexing, rate adaption and support of existing interfaces Aspects of ISDN affecting terminal requirements SERVICE CAPABILITIES OVERALL NETWORK ASPECTS AND FUNCTIONS ISDN USER-NETWORK INTERFACES MAINTENANCE PRINCIPLES B-ISDN EQUIPMENT ASPECTS ATM equipment Management of ATM eq
6、uipment I. I 00-1.1 99 1.110-1.119 1.120-1.129 I. 130-1.139 I. 140-1.149 1.1 50-1.199 1.200-1.299 I .200-1.209 I .2 1 0-1.2 1 9 1.220-1.229 1.230-1.239 I .24O-l .249 1.250-1.299 I .30O-l.399 I ,310-1.319 I. 320-1.329 1.330-1.339 1.340-1.349 I. 350-1.359 1.360-1.369 1.370-1.399 I .400-1.499 I .420-1.
7、429 1.430-1.439 1.440-1.449 1.450-1.459 I .460-1.469 l.50-i.699 I .470-1.499 1.600-1.699 I .700-1.799 I .730-1.749 1.750-1.799 For ficrther details, please refer to ITU-T List of Recommendations. - STD.ITU-T RECMN 1.525-ENGL 199b m 4b2591 Ub3591B T7b 9 ITU-T RECOMMENDATION 1.525 INTERWORKING BETWEEN
8、 NETWORKS OPERATING AT BIT RATES LESS THAN 64 kbit/s WITH 64 kbit/s-BASED ISDN AND B-ISDN Source ITU-T Recommendation 1.525 was revised by ITU-T Study Group 13 (1993-1996) and was approved under the WTSC Resolution No. 1 procedure on the 27th of August 1996. STD-ITU-T RECMN 1.525-ENGL L99b LiAb259L
9、Ob35719 902 = FOREWORD ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (IT-T) is a permanent organ of the IT. The ITU-T is responsible for studying technical, operating and tarif
10、f questions 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 ITU-T Study Groups which, in their turn, produce
11、Recommendations on these topics. The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1. In some areas of information technology which fall within IT-Ts purview, the necessary standards are prepared on a collaborative basis with IS0
12、 and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. INTELLECTUAL PROPERTY RIGHTS The IT draws attention to the possibility that the practice or implementation of this Rec
13、ommendation may involve the use of a claimed Intellectual Property Right. The IT 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 o
14、f approval of this Recommendation, the ITU hadhad not 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 con
15、sult the TSB patent database. O ITU 1997 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 the ITU. 11 Recommendation 1.525 (08/96) STD-ITU-T R
16、ECMN 1.525-ENGL 199b m 48b259L b35720 b24 - 1 2 3 4 4.1 4.2 5 6 6.1 6.2 CONTENTS General . Scope Principles Interworking configurations . General interworking configuration . Interworking configurations between ISDN and access networks operating at bit rates of less than 64 kbit/s Examples of applic
17、ations Interworking between B-ISDN and networks operating at bit rates of less than 64 kbit/s Interworking principles . 6.2.1 Indirect interworking scenario . 6.2.2 Direct interworking scenario . Interworking configurations . Annex A . Network interworking between an ISDN and an integrated digital n
18、etwork at a basic rate of 32 kbit/s (IDN-32) A.l General A.3.1 A.3.2 A.3.3 A.3.4 A.3.5 A.3.6 A.2 Scope A.3 Interworking configuration and network characteristics Interworking configuration Services suitable for IDN-32-ISDN interworking . Connection types suitable for IDN-32-ISDN interworking Functio
19、nal requirements for IDN-32-ISDN interworking . Key IDN-32 and ISDN characteristics and related interworking functions Handling of non-voice calls between IDN-32 and ISDN subscribers . Appendix A.l . Integrated digital network at a basic rate of 32 kbit/s (IDN-32) . A.I.l General A.I.2 Scope . A.I.3
20、 Principles . A.I.4 Access configuration . Annex B . Network interworking between an ISDN and a Digital Public Land Mobile Network (D-PLMN) . B.l General B.2 Scope Recommendation 1.525 (08196) Page 1 1 1 2 3 4 4 4 4 4 5 5 6 7 8 iii B .3 Intenvorking configuration and network characteristics B.3.1 In
21、terworking configuration B.3.2 Key D-PLMN and ISDN characteristics and related interworking functions B.3.3 Services suitable for D-PLMN-ISDN interworking B .3.4 Functional requirements for D-PLMN-ISDN intenvorking Appendix B.1 - D-PLMN B.I.1 General B.I.2 Scope . B.I.3 Principles . Page 9 9 9 10 10
22、 12 12 12 12 iv Recommendation 1.525 (OS/96) Recommendation 1.525 INTERWORKING BETWEEN NETWORKS OPERATING AT BIT RATES LESS THAN 64 kbit/s WITH 64 kbit/s-BASED ISDN AND B-ISDN (revised in 1996) 1 General Along with the adoption of ISDN, there is an increasing number of public digital networks being
23、established which rely on bit rates of less than 64 kbit/s. Though some of these may be national options or specialized applications, in many cases these networks will require to intenvork with public ISDNs. In the text of this Recommendation, “ISDN“ is used to identie 64 kbit/s-based ISDN and “B-IS
24、DN“ to describe broadband ISDNs. 2 Scope The purpose of this Recommendation is to describe the intenvorking arrangements between ISDN and networks operating at bit rates less than 64 kbiis. Examples of such digital networks include: - local public networks provided as a national option, for example,
25、 a digital network based on a rate of 32 kbiis (IDN-32); mobile networks, including cellular networks; - - Personal Communication Networks (PCNs); - private networks. 3 Principles Networks operating at less than 64 kbits and intenvorking with ISDN shall follow internationally- agreed 64 kbit/s-based
26、 ISDN interface standards for interconnecting with ISDN. In particular, they shall ensure time slot sequence integrity of the information conveyed in a 64 kbit/s channel at the intenvorking point. Any adaption and interworking functions to standard ISDN interfaces will be provided within the special
27、ized network (i.e. networks with rates less than 64 kbit/s). Principles and objectives for end-to-end service quality, compatibility, and essential service support are for further study. If both ends of a call terminate on similar networks which operate at less than 64 kbit/s, it would be desirable
28、if intenvorking functions such as speech transcoders were disabled. In such cases, the ISDN could, for example, provide a 64 kbit/s transparent path to interconnect the two sub-rate networks. The mechanism to achieve this is for further study. 4 Interworking configurations 4.1 General interworking c
29、onfiguration Figure 1 shows the general reference configuration for intenvorking. Recommendation 1.525 (08196) 1 I ISDN T1307030-95 Figure 1D.525 - General configuration for interworking between ISDN and networks which operate at bit rates of less than 64 kbit/s 4.2 Interworking between Access Netwo
30、rks (ANS) operating at bit rates of less than 64 kbit/s and ISDN based on the primary rate of 2048 kbits should be provided using V5 interface (V5.1 or V5.2). The interworking function at the point of the network interface includes speech signal transcoding, bit rates adaptation for non-speech infor
31、mation and signalling protocol conversion. It is provided in the LTE (Line Terminating Equipment). Figure 2 shows an AN operating at a bit rate of less than 64 kbits connected to an ISDN exchange using V5.1 interface. Interworking configurations between ISDN and access networks operating at bit rate
32、s of less than 64 kbit/s v5.1 1 1 n I T1307040-95 Figure 2D.525 - General V5.1 interface configuration for ANS operating at bit rates of less than 64 kbit/s In this case AN-ISDN connection is provided using m V5.1 links each transferring the information 64 k of n = - x 30 = m x 30 users, where k is
33、a bit rate of the subscriber line (k n subscriber lines by m AN-ISDN links or to serve n subscriber lines by s circuit mode 32 kbit/s, 8 kHz structured service, usable for voice or voiceband data; ii) circuit mode 32 kbit/s, 8 kHz structured service, usable for unrestricted 32 kbit/s. NOTE - IDN-32-
34、ISDN interworking means interworking both ways between IDN-32 and ISDN, while IDN-32 to ISDN refers to a call initiated in the IDN-32 and terminated in the ISDN, and ISDN to IDN-32 refers to a call initiated in the ISDN and terminated in the IDN-32. Services suitable for IDN-32-ISDN interworking (ci
35、rcuit mode) A.3.3.2 Currently there are two identified bearer services that could be used within ISDN to IDN-32 interworking. These are: i) circuit mode 64 kbit/s, 8 kHz structured bearer service, usable for speech information transfer; ii) circuit mode 64 kbits, 8 kHz structured bearer service, usa
36、ble for 3.1 kHz audio information transfer. Bearer services similar to those used within the IDN-32 to ISDN interworking can be used within the ISDN to IDN-32 interworking: i circuit mode 64 kbit/s, 8 kHz structured bearer service, usable for speech information transfer; ii) circuit mode 64 kbih, 8
37、kHz structured bearer service, usable for 3.1 kHz audio information transfer (Note 1); iii) circuit mode 64 kbits unrestricted, 8 kHz structured bearer service (Note 2). NOTE 1 - Transmission of 9600 bih voiceband data is for further study. NOTE 2 - For further study. Since one of these services - t
38、he 64 kbit/s unrestricted bearer services - can only be provided for individual IDN-32 users, during the setting up of a call, the ISDN call progress indicator will only recognize those users who can be provided with this bearer service. ISDN bearer services suitable for ISDN to IDN-32 interworking
39、(circuit mode) A.3.3.3 For further study. ISDN bearer services suitable for IDN-32-ISDN interworking (packet mode) A.3.3.4 Currently, there are two identified bearer services that could be used within ISDN for ISDN (packet mode call) to IDN-32 interworking: i B-channel: packet mode, unrestricted dig
40、ital information, service data unit integrity, X.25 link level, X.25 packet level bearer service; ii) D-channel: packet mode, unrestricted digital information, service data unit integrity, 1.44 1 link level, X.25 packet level bearer service. The bearer services described in this subclause are provid
41、ed within ISDN. Detailed mechanisms are for further study. ISDN bearer services suitable for ISDN to IDN-32 interworking (packet mode) A.3.4 This subclause identifies the mapping of ISDN bearer services and possible connection types for IDN-32-ISDN interworking. Depending on the specific ISDN bearer
42、 service being considered, more Connection types suitable for IDN-32-ISDN interworking 6 Recommendation 1.525 (08/96) than one ISDN connection type may be applicable. However, in some cases the connection type may not be fully compatible with requested bearer service, thereby leading to downgrading
43、of services. The ISDN bearer services and possible connection types for four IDN-32-ISDN interworking cases are given in Table A.2. Refer to Recommendation 1.335 for more details regarding the mapping between ISDN bearer services and ISDN connection types. Table A.2n.525 - ISDN bearer services and c
44、onnection types suitable for IDN-32-ISDN interworking Interworking I ISDN bearer services I ISDN connection types Y N FFS For further study. R NOTE 1 - It is recognized that IDN-32 services interworking with ISDN must use currently defined ISDN bearer services. NOTE 2 - It is possible that the servi
45、ce obtained on each of the bearer services for IDN-32 to ISDN interworking may not be the same as that obtained for ISDN to ISDN configurations. NOTE 3 - Refer to Recommendation 1.23 1 for the service definition for 64 kbitls interworking. Various mechanisms for ISDN - other networks interworking su
46、pporting Y-Series terminals connected to the ISDN using the 64 kbitls unrestricted bearer service are contained in Recommendation 1.5 15. Procedures require further study. NOTE 4 - Other ISDN bearer services and connection types that may be applicable for IDN-32-ISDN interworking are for further stu
47、dy. Yes - Can be used (some interworking scenarios may require further study). No - Cannot be used. Can be used except when A/m-law conversion and echo-control may be required. A.3.5 A.3.5.1 Interworking between signalling systems Since IDN-32 uses SS No. 7 ISUP, no new interworking requirements are
48、 identified. Functional requirements for IDN-32-ISDN interworking Recommendation 1.525 (08196) 7 - - STD-ITU-T RECMN 1.525-ENGL 199b 4862533 Ob35929 851 A.3.5.2 Provision of interworking indications An intenvorking indication is required for the ISDN local exchange to know that interworking has occu
49、rred. ISUP 4.761-4.764 and 1.45114.93 1 protocols have the ability to identi this intenvorking situation to the ISDN local exchange and the ISDN terminal (call progress indicator). The ISDN terminal would be informed in every case that intenvorking has occurred. Procedures are for further study. A.3.5.3 Failure indication Failure indication, when carried by the 1.451 and ISUP signalling messages, should be meaningful and give a clear indication of the reason. A.3.6 For some cases of IDN-32-ISDN interworking the capability to interconnect
