1、 International Telecommunication Union ITU-T Y.2021TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (09/2006) SERIES Y: GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS Next Generation Networks Frameworks and functional architecture models IMS for Next Generat
2、ion Networks ITU-T Recommendation Y.2021 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.300Y.399 Interface
3、s 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 capabilities and
4、 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 functional architect
5、ure 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 management Y.2400Y.
6、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.2021 (09/2006) i ITU-T Recommendation Y.2021 IMS for Next Generation Networks Summary The IP mult
7、imedia subsystem (IMS) has been adopted, and will be adapted as required, to support session-based services, and other services based on session initiation protocol (SIP). This Recommendation describes how the IMS can be used in the NGN context following the fundamental principles described in ITU-T
8、 Y.2001 and ITU-T Y.2011 for providing the IP multimedia service component of the NGN functional architecture and describes its relationships to other service components. Source ITU-T Recommendation Y.2021 was approved on 13 September 2006 by ITU-T Study Group 13 (2005-2008) under the ITU-T Recommen
9、dation A.8 procedure. ii ITU-T Rec. Y.2021 (09/2006) 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 st
10、udying 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 study gr
11、oups 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 with
12、 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 provis
13、ions (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 of such
14、 words does not suggest that compliance with 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
15、 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, protected
16、 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 2007 All rights reserved. No part of th
17、is publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. Y.2021 (09/2006) iii 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 2 5 Conventions 3
18、6 Overview 3 6.1 Introduction to IMS 3 6.2 Use of IMS in NGN 3 7 Functional entities. 5 7.1 Call session control function (CSCF). 5 7.2 Media gateway control function (MGCF) 6 7.3 Multimedia resource function controller (MRFC) . 6 7.4 Breakout gateway control function (BGCF) 6 8 Internal reference p
19、oints . 6 8.1 Reference point MGCF CSCF (Mg reference point) 6 8.2 Reference point CSCF MRFC (Mr reference point) . 7 8.3 Reference point CSCF CSCF (Mw reference point). 7 8.4 Reference point CSCF BGCF (Mi reference point) 7 8.5 Reference point BGCF MGCF (Mj reference point) 7 8.6 Reference point BG
20、CF BGCF (Mk reference point) 7 8.7 Reference point CSCF or BGCF IBC-FE (Mx reference point) . 7 9 IMS external reference points. 8 9.1 Reference points with entities in the transfer plane 8 9.2 Reference point CSCF UE (Gm reference point) 8 9.3 Reference points with the user profile 8 9.4 Reference
21、points to application servers 9 9.5 Reference points to the charging environment. 9 10 Reference points to external networks 9 10.1 Reference points with the PSTN/ISDN 9 10.2 Reference points with other IP-based service components 10 11 Mapping between 3GPP IMS functional entities and NGN functional
22、 entities . 10 Appendix I Relevant IMS specifications in the context of the NGN functional architecture . 11 Bibliography. 12 ITU-T Rec. Y.2021 (09/2006) 1 ITU-T Recommendation Y.2021 IMS for Next Generation Networks 1 Scope The IP multimedia subsystem (IMS) as specified by the 3rd Generation Partne
23、rship Project (3GPP) and the 3rd Generation Partnership Project 2 (3GPP2), has been adopted, and will be adapted as required, to support session-based services, and other services based on session initiation protocol (SIP). This Recommendation describes how the IMS can be used in the NGN context fol
24、lowing the fundamental principles described in ITU-T Y.2001 and ITU-T Y.2011. This Recommendation identifies the IMS for use in NGN and describes the use of the IMS in providing the IP multimedia service component of the NGN functional architecture and describes its relationships to other service co
25、mponents. It further identifies those IMS architecture documents that are relevant in the context of NGN. For more detail refer to ITU-T Y.2012. Administrations may require operators and service providers to take into account national regulatory and national policy requirements in implementing this
26、Recommendation. 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 Recommendations and other references are su
27、bject 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 regularly published. The reference to a documen
28、t within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T Q.1741.4 ITU-T Recommendation Q.1741.4 (2005), IMT-2000 references to release 6 of GSM evolved UMTS core network. ITU-T Q.1742.4 ITU-T Recommendation Q.1742.4 (2005), IMT-2000 references (
29、approved as of 30 June 2004) to ANSI-41 evolved core network with cdma2000 access network. ITU-T Y.101 ITU-T Recommendation Y.101 (2000), Global Information Infrastructure terminology: Terms and definitions. ITU-T Y.2001 ITU-T Recommendation Y.2001 (2004), General overview of NGN. ITU-T Y.2011 ITU-T
30、 Recommendation Y.2011 (2004), General principles and general reference model for Next Generation Networks. ITU-T Y.2012 ITU-T Recommendation Y.2012 (2006), Functional requirements and architecture of the NGN. ETSI TS 123 002 ETSI TS 123 002 V7.1.0 (2006), Digital cellular telecommunications system
31、(Phase 2+); Universal Mobile Telecommunications System (UMTS); Network architecture. ETSI TS 123 228 ETSI TS 123 228 V7.3.0 (2006), Digital cellular telecommunications system (Phase 2+); Universal Mobile Telecommunications System (UMTS); IP Multimedia Subsystem (IMS); Stage 2. TIA-873.002 TIA-873.00
32、2-A (2006), All-IP Core Multimedia Domain, IP Multimedia Subsystem Stage 2. 2 ITU-T Rec. Y.2021 (09/2006) 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following term defined elsewhere: 3.1.1 reference point ITU-T Y.101: A conceptual point at the conjunction of two non-overl
33、apping functional groups. 3.2 Terms defined in this Recommendation This Recommendation defines the following terms: 3.2.1 home network: The network to which a mobile user is normally connected, or the service provider with which the mobile user is associated, and where the users subscription informa
34、tion is managed. 3.2.2 visited network: The network outside a home network that provides service to a mobile user. This term is more business significant than geographically significant. 4 Abbreviations This Recommendation uses the following abbreviations: ALG Application Layer Gateway AS-FE Applica
35、tion Server Functional Entity BGCF Breakout Gateway Control Function CSCF Call Session Control Function HSS Home Subscriber Service IBC-FE Interconnection Border gateway Controller Functional Entity IBG-FE Interconnection Border Gateway Functional Entity I-CSCF Interrogating CSCF IMS IP Multimedia S
36、ubsystem IP Internet Protocol ISC IMS Service Control I-SIM IMS Subscriber Identity Module MGCF Media Gateway Control Function MRFC Multimedia Resource Function Controller MRP-FE Multimedia Resource Processor Functional Entity NAPT Network Address and Port Translation NGN Next Generation Network NSI
37、W-FE Network Signalling Interworking Functional Entity P-CSCF Proxy CSCF PLMN Public Land Mobile Network PSTN Public Switched Telephone Network RACF Resource and Admission Control Functions SAA-FE Service Authentication and Authorization Functional Entity ITU-T Rec. Y.2021 (09/2006) 3 S-CSCF Serving
38、 CSCF SDP Session Description Protocol SG-FE Signalling Gateway Functional Entity SIP Session Initiation Protocol SL-FE Subscription Locator Functional Entity SPIRITS Service in the PSTN/IN Requesting InTernet Services SUP-FE Service User Profile Functional Entity TMG-FE Trunking Media Gateway Funct
39、ional Entity UE User Equipment WLAN Wireless Local Area Network xDSL x-Digital Subscriber Line 5 Conventions None. 6 Overview 6.1 Introduction to IMS IMS is a collection of core network functional entities for the support of SIP-based services ETSI TS 123 228, TIA-873.002. IMS supports the registrat
40、ion of the user and the terminal device at a particular location in the network. As part of registration, IMS supports authentication and other security arrangements. IMS utilizes SIP-based control. The services supported by IMS may include multimedia session services and some non-session services s
41、uch as Presence services or message exchange services. In addition to services for the user, IMS defines a number of network reference points to support operator-provided services. IMS supports various application services via the services support architecture. IMS supports operation and interworkin
42、g with a variety of external networks via defined reference points. IMS supports defined reference points for the collection of accounting data in support of charging and billing operations. IMS also supports defined reference points within the underlying transport infrastructure for the enforcement
43、 of QoS negotiated by session signalling and for flow gating. These reference points also support the exchange of information in support of correlation of charging between IMS and the underlying transport. Appendix I contains a list of documents defining IMS which are relevant in the context of NGN.
44、 6.2 Use of IMS in NGN 6.2.1 General The NGN IP multimedia service (IMS) component supports the provision of SIP-based multimedia services to NGN terminals. It also supports the provision of PSTN/ISDN simulation services. This clause provides details about the IP multimedia subsystem and the adaptat
45、ion and extension of the IMS specifications to support additional access network types, such as those based on xDSL and WLAN. IMS and its extensions support the following: control of IP connectivity access networks (QoS, admission control, authentication, etc.); 4 ITU-T Rec. Y.2021 (09/2006) coordin
46、ation of multiple control components to a single core transport for resource control; interworking and interoperability with legacy and other networks; mutual de-coupling of the applications from the session/call control and the transport; access technology independence of session/call control and a
47、pplications. Functional entities of an IMS may be used by an operator in support of transit network scenarios. The routing may be performed, depending on the entity performing the routing, and depending on the traffic case, signalling information, configuration data, and/or database lookup. The refe
48、rences contained in Appendix I are considered to be relevant in the NGN architecture. The access networks able to be supported by the Release 7 versions of these documents mostly focus on DSL access. 6.2.2 Relationship between IMS and NGN IMS is comprised of a number of functional entities that toge
49、ther can provide support for the capabilities of the service stratum of NGN ITU-T Y.2012. The following functional entities are defined in IMS as specified by the documents in Appendix I. The IMS functional entities and their environment are illustrated in Figure 6-1. Figure 6-1 IMS and its environment ITU-T Rec. Y.2021 (09/2006) 5 Figure 6-1 shows the set of functional entities that comprise IMS. IMS, as a collection of core network functional entities may be utilized by both home networks and
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