1、 International Telecommunication Union ITU-T Y.2261 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (09/2006) SERIES Y: GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS Next Generation Networks Service aspects: Interoperability of services and networks in NGN
2、 PSTN/ISDN evolution to NGN ITU-T Recommendation Y.2261 ITU-T Y-SERIES RECOMMENDATIONS GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT- GENERATION NETWORKS GLOBAL INFORMATION INFRASTRUCTURE General Y.100Y.199 Services, applications and middleware Y.200Y.299 Network aspects Y.30
3、0Y.399 Interfaces and protocols Y.400Y.499 Numbering, addressing and naming Y.500Y.599 Operation, administration and maintenance Y.600Y.699 Security Y.700Y.799 Performances Y.800Y.899 INTERNET PROTOCOL ASPECTS General Y.1000Y.1099 Services and applications Y.1100Y.1199 Architecture, access, network
4、capabilities and resource management Y.1200Y.1299 Transport Y.1300Y.1399 Interworking Y.1400Y.1499 Quality of service and network performance Y.1500Y.1599 Signalling Y.1600Y.1699 Operation, administration and maintenance Y.1700Y.1799 Charging Y.1800Y.1899 NEXT GENERATION NETWORKS Frameworks and func
5、tional architecture models Y.2000Y.2099 Quality of Service and performance Y.2100Y.2199 Service aspects: Service capabilities and service architecture Y.2200Y.2249 Service aspects: Interoperability of services and networks in NGN Y.2250Y.2299 Numbering, naming and addressing Y.2300Y.2399 Network man
6、agement Y.2400Y.2499 Network control architectures and protocols Y.2500Y.2599 Security Y.2700Y.2799 Generalized mobility Y.2800Y.2899 For further details, please refer to the list of ITU-T Recommendations. ITU-T Rec. Y.2261 (09/2006) i ITU-T Recommendation Y.2261 PSTN/ISDN evolution to NGN Summary T
7、his Recommendation describes principle aspects of evolving PSTN/ISDN to NGN. Evolution of PSTN/ISDN to NGN, based on IP multimedia sub-system (IMS-based) and call server, (CS-based) is described. It mainly describes evolution of transport parts of PSTN/ISDN to NGN. Some evolution scenarios are also
8、provided in appendices. Source ITU-T Recommendation Y.2261 was approved on 13 September 2006 by ITU-T Study Group 13 (2005-2008) under the ITU-T Recommendation A.8 procedure. Keywords Access gateway, Access network, Application server, Call server, Evolution, ISDN, NGN, PSTN. ii ITU-T Rec. Y.2261 (0
9、9/2006) 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. ITU-T is responsible for studying technical, operating and tariff questi
10、ons 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 study groups which, in turn, produce Recommendations
11、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 with ISO and IEC. NOTE In this Recommendation, th
12、e 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 provisions (to ensure e.g. interoperability or appl
13、icability) 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 of such words does not suggest that compliance with
14、the Recommendation is required of any party. 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. ITU takes no position concerning the evidence, validity or applica
15、bility 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, protected by patents, which may be required to impleme
16、nt 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 2007 All rights reserved. No part of this publication may be reproduced, by any mean
17、s whatsoever, without the prior written permission of ITU. ITU-T Rec. Y.2261 (09/2006) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Definitions 2 4 Abbreviations 3 5 Conventions 5 6 PSTN/ISDN evolution to NGN 5 7 Aspects to consider when evolving to NGN. 5 7.1 Transport. 5 7.2 Signalling and contro
18、l. 6 7.3 Management. 6 7.4 Services. 6 7.5 Operation, administration and maintenance (OAM) 7 7.6 Naming, numbering and addressing. 7 7.7 Accounting, charging and billing . 7 7.9 Call routing. 9 8 Service requirements by national regulatory bodies. 9 9 Emergency telecommunications in NGN . 10 10 Secu
19、rity aspects of evolution 10 Appendix I Examples of network evolution scenarios . 11 I.1 Core network evolution to NGN 11 I.2 Access network evolution. 17 I.3 Signalling and control scenarios. 19 I.4 Management scenarios . 19 I.5 Services evolution scenarios. 20 Appendix II Examples of PSTN/ISDN ser
20、vice evolution 24 Appendix III Billing system evolution scenarios 25 BIBLIOGRAPHY 26 ITU-T Rec. Y.2261 (09/2006) 1 ITU-T Recommendation Y.2261 PSTN/ISDN evolution to NGN 1 Scope A public switched telephone network or integrated services digital network (PSTN/ISDN) being one of the networks in teleco
21、mmunication is considered to be a prime candidate for evolution to the next generation network (NGN) Y.2001 and Y.2011. Because of the widespread deployment and the use of PSTN/ISDN, evolution to NGN should be considered as a step-wise approach. This Recommendation describes possible ways of evolvin
22、g PSTN/ISDN to NGN. Both the IP multimedia sub-system (IMS-based) and call server (CS-based) are described. It describes aspects, which need to be considered including evolution of transport, management, signalling and control parts of PSTN/ISDN to NGN. Evolution scenarios are also provided in appen
23、dices. Administrations may require operators and service providers to take into account national regulatory and national policy requirements in implementing this Recommendation. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this
24、text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent editio
25、n of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. G.964 ITU-T Recommendation G.964
26、 (2001), V-interfaces at the digital local exchange (LE) V5.1 interface (based on 2048 kbit/s) for the support of access network (AN). G.965 ITU-T Recommendation G.965 (2001), V-interfaces at the digital local exchange (LE) V5.2 interface (based on 2048 kbit/s) for the support of access network (AN)
27、. I.610 ITU-T Recommendation I.610 (1999), B-ISDN operation and maintenance principles and functions. M.3010 ITU-T Recommendation M.3010 (2000), Principles for a telecommunications management network. M.3400 ITU-T Recommendation M.3400 (2000), TMN management functions. Q.310-Q.332 ITU-T Recommendati
28、on Q.310-Q.332 (1988), Specifications of signalling system R1. Q.400-Q.490 ITU-T Recommendation Q.400-Q.490 (1988), Specifications of signalling system R2. Q.931 ITU-T Recommendation Q.931 (1998), ISDN user-network interface layer 3 specification for basic call control. Q.1741.3 ITU-T Recommendation
29、 Q.1741.3 (2003), IMT-2000 references to release 5 of GSM evolved UMTS core network. Q.1912.5 ITU-T Recommendation Q.1912.5 (2004), Interworking between Session Initiation Protocol (SIP) and Bearer Independent Call Control protocol or ISDN User Part. 2 ITU-T Rec. Y.2261 (09/2006) X.462 ITU-T Recomme
30、ndation X.462 (1996), Information technology Message Handling Systems (MHS) Management: Logging information. Y.1411 ITU-T Recommendation Y.1411 (2003), ATM-MPLS network interworking Cell mode user plane interworking. Y.1541 ITU-T Recommendation Y.1541 (2006), Network performance objectives for IP-ba
31、sed services. Y.1710 ITU-T Recommendation Y.1710 (2002), Requirements for operation Universal Mobile Telecommunications System (UMTS); Service aspects; Charging and billing. 3 Definitions This Recommendation defines the following terms: NOTE In this clause, aaa notation after title of a term indicat
32、es source of the definition for that term. 3.1 access gateway (AG): A unit that allows end users with various accesses (e.g., PSTN, ISDN, V5.x) connection to the packet node of NGN. NOTE The AG may be embedded in an access node, which also serves other access interfaces (e.g., xDSL, LAN). Such acces
33、s nodes are also known as multi-service access nodes (MSAN). 3.2 access network (AN): See G.964. 3.3 accounting: See X.462. 3.4 application: A structured set of capabilities, which provide value-added functionality supported by one or more services, which may be supported by an API interface. 3.5 ap
34、plication server (AS) Y.2271: A unit that interacts with the call server and the user profile server to support service execution. 3.6 billing: See Q.1741.3. 3.7 call server (CS) Y.2271: The core element of a CS-based PSTN/ISDN emulation component which is responsible for call control, media resourc
35、e control, call routing, user profile and subscriber authentication, authorization and accounting. Depending on its role, the behaviour of the call server may be different. In these cases, the role of the call server is identified, for example, as “Access call server“, “Breakout call server“, “IMS c
36、all server“, “Routing call server“ or “Gateway call server“. 3.8 charging: See Q.1741.3. 3.9 evolution to NGN: A process in which whole or parts of the existing networks are replaced or upgraded to the corresponding NGN components providing similar or better functionality, while attempting to mainta
37、in the services provided by the original network and the possibility of additional capabilities. ITU-T Rec. Y.2261 (09/2006) 3 3.10 gateway: A unit that interconnects different networks and performs the necessary translation between the protocols used in these networks. 3.11 media server (MS) Y.2271
38、: A network element providing the media resource processing function for telecommunication services in NGN. 3.12 remote user access module (RUAM): A unit that physically terminates subscriber lines and converts the analogue signals into a digital format. The RUAM is physically remote from the local
39、exchange. 3.13 signalling gateway (SG): A unit that provides out-of-band call control signalling conversion between the NGN and other networks (e.g., between a call server in NGN and an STP or SSP in SS7). 3.14 trunking media gateway (TMG): A unit that provides interfaces between the packet nodes of
40、 the NGN and the circuit-switched nodes (e.g., transit exchange, local exchange, international exchange) of PSTN/ISDN for bearer traffic. The TMG provides any needed conversion to the bearer traffic. 3.15 user access module (UAM): A unit that physically terminates subscriber lines and converts the a
41、nalogue signals into a digital format. The UAM is collocated with a local exchange, and is connected to the local exchange. 4 Abbreviations This Recommendation uses the following abbreviations: ACS Access Call Server AG Access Gateway AN Access Network API Application Programming Interface AS Applic
42、ation Server ATM Asynchronous Transfer Mode BCS Breakout Call Server BICC Bearer Independent Call Control CAS Channel Associated Signalling CCS Common Channel Signalling CDR Call Detail Record CS Call Server CT Content of Telecommunication DSL Digital Subscriber Line DSLAM Digital Subscriber Line Ac
43、cess Multiplexer DSS1 Digital Signalling System No. 1 DTMF Dual Tone Multi Frequency ETS Emergency Telecommunications Services FTTC Fibre-To-The-Curb 4 ITU-T Rec. Y.2261 (09/2006) FTTH Fibre-To-The-Home GCS Gateway Call Server ICS IMS Call Server IMS IP Multimedia Subsystem IN Intelligent Network IN
44、AP Intelligent Network Application Part IP Internet Protocol IPTV IP Television IRI Intercept-Related Information ISDN Integrated Services Digital Network IVR Interactive Voice Response LE Local Exchange LEA Law Enforcement Agencies MS Media Server MSAN Multi-Service Access Node NGN Next Generation
45、Network N-ISDN Narrowband ISDN OSS Operations Support System PBX Private Branch eXchange PLMN Public Land Mobile Network POTS Plain Old Telephone Service PSAP Public Safety Answering Point PSN Packet Switched Network PSTN Public Switched Telephone Network QoS Quality of Service RCS Routing Call Serv
46、er RUAM Remote User Access Module SCE Service Creation Environment SCP Service Control Point SG Signalling Gateway SIP Session Initiation Protocol SS7 Signalling System No. 7 SSF Service Switching Function SSP Service Switching Point STP Signalling Transfer Point TDR Telecommunications for Disaster
47、Relief TE Transit Exchange ITU-T Rec. Y.2261 (09/2006) 5 TMG Trunking Media Gateway UAM User Access Module URI Uniform Resource Identifier VoD Video on Demand VoIP Voice over IP xDSL any DSL 5 Conventions None. 6 PSTN/ISDN evolution to NGN The PSTN/ISDN is the prime candidate for evolution to NGN an
48、d, as such, all aspects should be carefully examined and appropriate measures should be taken. In general, PSTN/ISDN is comprised of the following entities, each with one or multiple functionalities: Transport (access plus core): user access module (UAM), remote user access module (RUAM), access net
49、work (AN) via V5.1/2 G.964 and G.965 interface connected to the core switches and the core switches themselves. Control and signalling: exchange hosts. Management: management of exchanges. Service: exchange hosts and auxiliary network (e.g., IN). In PSTN/ISDN, most of the functionalities are located in a single exchange and may use proprietary protocols. However, in the NGN, functionalities may be distributed amongst several elements. The following clauses provide detailed steps for ev
