1、 International Telecommunication Union ITU-T Y.2031TELECOMMUNICATION 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 PSTN/ISDN emulation
2、architecture ITU-T Recommendation Y.2031 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.2031 (09/2006) i ITU-T Recommendation Y.2031 PSTN/ISDN emulation architecture Summary This Recomm
7、endation describes the functional architecture, interworking with other components, and reference point requirements of the PSTN/ISDN emulation service component (NGN component of the service stratum) including call server based approach and IMS-based approach. Source ITU-T Recommendation Y.2031 was
8、 approved on 13 September 2006 by ITU-T Study Group 13 (2005-2008) under the ITU-T Recommendation A.8 procedure. ii ITU-T Rec. Y.2031 (09/2006) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunicat
9、ion Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for 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 (
10、WTSA), which meets every four years, establishes the topics for study by the ITU-T study 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 fal
11、l within ITU-Ts purview, the necessary standards are prepared on a collaborative basis 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 Re
12、commendation is voluntary. However, the Recommendation may contain certain mandatory provisions (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 su
13、ch as “must“ and the negative equivalents are used to express requirements. The use of such 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 Recomme
14、ndation may involve the use of a claimed Intellectual Property Right. ITU 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 of appro
15、val of this Recommendation, ITU had not received notice of intellectual property, protected 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 p
16、atent database at http:/www.itu.int/ITU-T/ipr/. ITU 2007 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. Y.2031 (09/2006) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Definitions 1 4 Abbreviations 2
17、 5 PSTN/ISDN emulation in NGN . 4 6 Call server based PSTN/ISDN emulation functional architecture . 4 6.1 Description of functions . 5 6.2 Service architecture 7 6.3 Reference points . 8 6.4 Relationship between functional entities in CS-based PSTN/ISDN emulation functional architecture and NGN arch
18、itecture. 10 6.5 Interworking with other service components . 10 6.6 Interconnection with RACF . 11 6.7 Interconnection with NACF . 11 6.8 Interworking with other networks 11 7 IMS-based PSTN/ISDN emulation functional architecture . 12 7.1 Overview 12 7.2 Overview of functional entities of the IMS-P
19、ES 13 7.3 Internal reference points. 15 7.4 Service architecture 16 7.5 External reference points 17 7.6 Interconnection with other networks 19 7.7 Reference points with the network attachment control function (NACF) . 19 7.8 Reference point with the resource and admission control function (RACF). 1
20、9 7.9 Mode of operation 20 7.10 Mapping between IMS-PES functional entities and NGN functional entities. 22 Bibliography. 23 ITU-T Rec. Y.2031 (09/2006) 1 ITU-T Recommendation Y.2031 PSTN/ISDN emulation architecture 1 Scope This Recommendation describes the functional architecture, interworking with
21、 other components, and reference point requirements of the PSTN/ISDN emulation service component including call server based approach and IMS-based approach. Administrations may require operators and service providers to take into account national regulatory and national policy requirements in imple
22、menting this 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 refe
23、rences 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 regularly published. The reference
24、 to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T H.248.1 ITU-T Recommendation H.248.1 (2005), Gateway control protocol: Version 3. ITU-T Q.512 ITU-T Recommendation Q.512 (1995), Digital exchange interfaces for subscriber acc
25、ess. ITU-T Q.1214 ITU-T Recommendation Q.1214 (1995), Distributed functional plane for intelligent network CS-1. ITU-T Y.2012 ITU-T Recommendation Y.2012 (2006), Functional requirements and architecture of the NGN. ITU-T Y.2111 ITU-T Recommendation Y.2111 (2006), Resource and admission control funct
26、ions in Next Generation Networks. 3 Definitions This Recommendation uses or defines the following terms: 3.1 access gateway: 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 serves a
27、lso other access interfaces (e.g., xDSL, LAN). Such access nodes are also known as multi-service access nodes (MSAN). 3.2 access media gateway: A unit that provides interworking between the packet-based transport used in the NGN and analogue lines or ISDN access. 3.3 call server: The core element of
28、 a CS-based PSTN/ISDN emulation component, which is responsible for call control, media resource 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 call
29、server is identified for example as “Access call server“, “Breakout call server“, “IMS call server“, “Routing call server“ or “Gateway call server“. 3.4 functional entity: An entity that comprises an indivisible set of specific functions. Functional entities are logical concepts, while groupings of
30、functional entities are used to describe practical, physical implementations. 2 ITU-T Rec. Y.2031 (09/2006) 3.5 functional architecture: A set of functional entities and the reference points between them used to describe the structure of an NGN. These functional entities are separated by reference p
31、oints, and thus, they define the distribution of functions. NOTE The functional entities can be used to describe a set of reference configurations. These reference configurations identify which reference points are visible at the boundaries of equipment implementations and between administrative dom
32、ains. 3.6 media gateway: The media gateway (MG) converts media provided in one type of network to the format required in another type of network. For example, a MG could terminate bearer channels from a switched circuit network (e.g., DS0s) and media streams from a packet network (e.g., RTP streams
33、in an IP network). This gateway may be capable of processing audio, video and multimedia conferencing alone or in any combination, and will be capable of full duplex media translations. The MG may also play audio/video messages and perform other interactive voice response (IVR) functions, or may per
34、form media conferencing. In this Recommendation, media gateway refers both to access gateways and residential gateways. 3.7 media gateway controller: Controls the parts of the call state that pertain to connection control for media channels in a media gateway. 3.8 reference point: A conceptual point
35、 at the conjunction of two non-overlapping functional entities that can be used to identify the type of information passing between these functional entities. NOTE A reference point may correspond to one or more physical interfaces between pieces of equipment. 3.9 residential gateway: A unit that in
36、terworks PSTN/ISDN user equipments to a packet network. A residential gateway is located at the customer premises. 3.10 voice over IP gateway: A SIP-based gateway that connects legacy terminals to the NGN. When connecting analogue lines, the voice over IP gateway includes at least an analogue teleph
37、one adaptor (ATA). A voice over IP gateway (VGW) plays the role of an IMS UE with regard to the P-CSCF. 4 Abbreviations This Recommendation uses the following abbreviations: ABG-FE Access Border Gateway Functional Entity AGCF Access Gateway Control Function AMG Access Media Gateway AMG-FE Access Med
38、ia Gateway Functional Entity APL-GW-FE Application Gateway Functional Entity AS Application Server AS-FE Application Server Functional Entity BGCF Breakout Gateway Control Function CCF Call Control Function CS Call Server CSCF Call Session Control Function CS-PES Call Server based PSTN/ISDN Emulatio
39、n Service component FE Functional Entity IBC-FE Interconnection Border Gateway Control Functional Entity ITU-T Rec. Y.2031 (09/2006) 3 IBG-FE Interconnection Border Gateway Functional Entity I-CSCF Interrogating CSCF IFN IMS for Next Generation Networks IMS IP Multimedia Service component IMS-PES IM
40、S based PSTN/ISDN Emulation Service component IN Intelligent Network IP Internet Protocol ISDN Integrated Services Digital Network MGCF Media Gateway Control Function MRCF Media Resource Control Function MRP-FE Media Resource Process Functional Entity NACF Network Attachment Control Function NGN Nex
41、t Generation Network NNI Network-to-Network Interface NSIW-FE Network Signalling Interworking Functional Entity OSA Open Service Architecture P-CSCF Proxy CSCF PES PSTN/ISDN Emulation Service component PSTN Public Switched Telephone Network RACF Resource and Admission Control Function RF Routing Fun
42、ction SAA-FE Service Authentication and Authorization Functional Entity SCP Service Control Point S-CSCF Serving CSCF S-CSC-FE Serving Call Session Control Functional Entity SG Signalling Gateway SG-FE Signalling Gateway Functional Entity SIF Signalling Interworking Function SIP Session Initiation P
43、rotocol SL-FE Subscription Locator Functional Entity SPF Service Provider Function SS7 Signalling System No. 7 SSF Service Switching Function SUP-FE Service User Profile Functional Entity TMG Trunking Media Gateway TMG-FE Trunking Media Gateway Functional Entity VGW Voice over IP Gateway 4 ITU-T Rec
44、. Y.2031 (09/2006) 5 PSTN/ISDN emulation in NGN As shown in Figure 5-1, PSTN/ISDN emulation, as one of the service components of NGN, provides PSTN/ISDN basic and supplementary services, and coexists with the IP multimedia service component, the streaming service component, and other service compone
45、nts. PSTN/ISDN emulation, as one of the service components of NGN, interworks with the existing network and other service components. It provides the emulation of PSTN/ISDN services for legacy terminal connected via residential gateways and access gateways to the NGN. Figure 5-1 PSTN/ISDN emulation
46、in NGN There are two solutions for PSTN/ISDN emulation service component, which are known as call server based emulation and IMS-based emulation. The two solutions are suitable for different network situations, but can provide equal emulation services. 6 Call server based PSTN/ISDN emulation functio
47、nal architecture This clause describes a functional architecture for CS-based PSTN/ISDN emulation. Figure 6-1 provides a detailed view of the functional entities and reference points that make up this architecture and shows their relationship with other service components of NGN architecture. ITU-T
48、Rec. Y.2031 (09/2006) 5 Figure 6-1 shows functions that comprise PSTN/ISDN emulation component. These as well as also several functional entities which are part of overall NGN functional architecture are described in ITU-T Y.2012. Figure 6-1 Functional architecture of CS-based PSTN/ISDN emulation 6.
49、1 Description of functions 6.1.1 Call control function (CCF) The call control function (CCF) provides the following functionalities: a) Two-party call control function and multi-party call control; b) Access to IN capabilities (e.g., passes events to the SSF); c) Access to PSTN/ISDN supplementary services in SPF; d) Access to applications (e.g., passes events to the SIF for AS-FE). 6.1.2 Access gateway control function (AGCF) The access gateway control function (AGCF) controls one or more AMG-FEs to access PSTN or ISDN users. It: a) is in c
