1、 International Telecommunication Union ITU-T Y.1452TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (03/2006) SERIES Y: GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS Internet protocol aspects Interworking Voice trunking over IP networks ITU-T Recommendation
2、 Y.1452 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 Interfaces and protocols Y.400Y.499 Number
3、ing, 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 resource management Y.1200Y.1299
4、 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 architecture models Y.2000Y.2099 Quality o
5、f 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.2499 Network control architecture
6、s 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.1452 (03/2006) i ITU-T Recommendation Y.1452 Voice trunking over IP networks Summary This Recommendation addresses required functi
7、ons for voice trunking over IP networks. It specifies the required protocols, the interactions between these protocols and audio channel mechanisms, the operation of the IWF, and the mechanisms for transporting over point-to-point or complex IP networks. This Recommendation may not be suitable for u
8、se by recognized operating agencies (ROA). Source ITU-T Recommendation Y.1452 was approved on 1 March 2006 by ITU-T Study Group 13 (2005-2008) under the ITU-T Recommendation A.8 procedure. Keywords Interworking, IP, network interworking, UDP, user plane, voice services, voice trunking, VoIP. ii ITU-
9、T Rec. Y.1452 (03/2006) 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 a
10、nd 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 groups which, in turn, produce
11、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 ISO and IEC. NOTE In this Re
12、commendation, 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 provisions (to ensure e.g. interope
13、rability 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 words does not suggest that
14、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 concerning the evidence, val
15、idity 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 by patents, which may be req
16、uired to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. ITU 2006 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, wi
17、thout the prior written permission of ITU. ITU-T Rec. Y.1452 (03/2006) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Definitions 3 4 Abbreviations and acronyms 3 5 Conventions 4 6 Voice trunking over IP networks 4 7 General requirements 5 7.1 User plane requirements. 5 7.2 Management plane aspects.
18、6 7.3 Fault management aspects 6 7.4 Traffic management aspects. 6 7.5 Connection admission control for the IWF 7 7.6 Congestion control 7 8 Functional group considerations for VToIP network interworking . 7 8.1 IP. 7 8.2 UDP 7 8.3 Common interworking indicators. 8 9 Payload format 9 10 Encapsulatio
19、n format 10 11 Aggregating VoIP streams 12 12 Security considerations. 13 iv ITU-T Rec. Y.1452 (03/2006) Introduction This Recommendation specifies the required functions and procedures necessary for support of narrow-band voice services by IP networks. Narrow-band voice services include digital aud
20、io streams, telephony call progress tones, facsimile, and optionally, circuit mode data. Details of the encapsulation of encoded audio streams are specified. ITU-T Rec. Y.1452 (03/2006) 1 ITU-T Recommendation Y.1452 Voice trunking over IP networks 1 Scope This Recommendation specifies the required f
21、unctions and procedures necessary for support of narrow-band voice services by IP networks. Narrow-band voice services include digital audio streams, telephony call progress tones, facsimile, and optionally, circuit mode data. This Recommendation specifies encapsulation of digital audio in IP packet
22、s. Algorithms for encoding audio streams are beyond the scope of this Recommendation. This Recommendation may not be suitable for use by recognized operating agencies (ROA). 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text
23、, 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 edition of
24、 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. 1 ITU-T Recommendation Y.1411 (2003)
25、, ATM-MPLS network interworking Cell mode user plane interworking. 2 ITU-T Recommendation G.809 (2003), Functional architecture of connectionless layer networks. 3 ITU-T Recommendation G.711 (1988), Pulse code modulation (PCM) of voice frequencies. 4 ITU-T Recommendation G.723.1 (1996), Dual rate sp
26、eech coder for multimedia communications transmitting at 5.3 and 6.3 kbit/s. 5 ITU-T Recommendation G.726 (1990), 40, 32, 24, 16 kbit/s Adaptive Differential Pulse Code Modulation (ADPCM). 6 ITU-T Recommendation G.727 (1990), 5-, 4-, 3- and 2-bit/sample embedded adaptive differential pulse code modu
27、lation (ADPCM). 7 ITU-T Recommendation G.729 (1996), Coding of speech at 8 kbit/s using conjugate-structure algebraic-code-excited linear-prediction (CS-ACELP). 8 ETSI EN 301 703 V7.0.2 (1999), Digital cellular telecommunications system (Phase 2+) (GSM) Adaptive Multi-Rate (AMR); Speech processing f
28、unctions; General description (GSM 06.71 version 7.0.2 Release 1998). 9 ITU-T Recommendation G.722 (1988), 7 kHz audio-coding within 64 kbit/s. 10 ITU-T Recommendation G.722.1 (2005), Low-complexity coding at 24 and 32 kbit/s for hands-free operation in systems with low frame loss. 11 ITU-T Recommen
29、dation G.722.2 (2003), Wideband coding of speech at around 16 kbit/s using Adaptive Multi-Rate Wideband (AMR-WB). 12 ITU-T Recommendation G.711 Appendix I (1999), A high quality low-complexity algorithm for packet loss concealment with G.711. 2 ITU-T Rec. Y.1452 (03/2006) 13 ITU-T Recommendation Q.2
30、3 (1988), Technical features of push-button telephone sets. 14 ITU-T Recommendation Q.24 (1988), Multifrequency push-button signal reception. 15 ITU-T Recommendation E.180/Q.35 (1998), Technical characteristics of tones for the telephone service. 16 ITU-T Recommendation I.251.3 (1992), Number identi
31、fication supplementary services: Calling Line Identification Presentation. 17 ITU-T Recommendation Q.310-Q.332 (1988), Specifications of Signalling System R1. 18 ITU-T Recommendation Q.400-Q.490 (1988), Specifications of Signalling System R2. 19 ITU-T Recommendation Q.724 (1988), Telephone user part
32、 signalling procedures, plus Amendment 1 (1993). 20 ITU-T Recommendation T.4 (2003), Standardization of Group 3 facsimile terminals for document transmission. 21 ITU-T Recommendation T.30 (2005), Procedures for document facsimile transmission in the general switched telephone network. 22 ITU-T Recom
33、mendation V.17 (1991), A 2-wire modem for facsimile applications with rates up to 14 400 bit/s. 23 ITU-T Recommendation V.29 (1988), 9600 bits per second modem standardized for use on point-to-point 4-wire leased telephone-type circuits. 24 ITU-T Recommendation V.18 (2000), Operational and interwork
34、ing requirements for DCEs operating in the text telephone mode. 25 IETF RFC 2474 (1998), Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers. 26 IETF RFC 3246 (2002), An Expedited Forwarding PHB (Per-Hop Behaviour). 27 IETF RFC 2210 (1997), The Use of RSVP with IE
35、TF Integrated Services. 28 IETF RFC 2212 (1997), Specification of Guaranteed Quality of Service. 29 IETF RFC 791 (1981), Internet Protocol. 30 IETF RFC 2460 (1998), Internet Protocol, Version 6 (IPv6) specification. 31 IETF RFC 768 (1980), User Datagram Protocol. 32 ITU-T Recommendation I.363.2 (200
36、0), B-ISDN ATM Adaptation Layer specification: Type 2 AAL. 33 ITU-T Recommendation I.366.2 (2000), AAL type 2 service specific convergence sublayer for narrow-band services, plus Corrigendum 1 (2002). 34 ATM Forum specification af-vmoa-0145.001 (2003), Loop Emulation Service Using AAL 2 Rev 1. 35 IE
37、TF RFC 3550 (2003), RTP: A Transport Protocol for Real-Time Applications. 36 ITU-T Recommendation I.366.1 (1998), Segmentation and Reassembly Service Specific Convergence Sublayer for the AAL type 2. 37 IETF RFC 2508 (1999), Compressing IP/UDP/RTP Headers for Low-Speed Serial Links. 38 IETF RFC 2507
38、 (1999), IP Header Compression. 39 IETF RFC 3095 (2001), Robust Header Compression (ROHC): Framework and four profiles: RTP, UDP, ESP, and uncompressed. ITU-T Rec. Y.1452 (03/2006) 3 40 ITU-T Recommendation X.800 (1991), Security architecture for Open Systems Interconnection for CCITT Applications.
39、3 Definitions This Recommendation uses or defines the following terms: 3.1 interworking: See ITU-T Rec. Y.1411 1. 3.2 interworking function (IWF): See ITU-T Rec. Y.1411. 3.3 ingress IWF: The point where the voice services are encapsulated into an IP packet (Voice-to-IP direction). 3.4 egress IWF: Th
40、e point where the voice services are de-encapsulated from an IP packet (IP-to-voice direction). 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms. AAL 2 ATM Adaptation Layer type 2 AMR Adaptive Multi-Rate CAC Connection Admission Control CAS Channel Assoc
41、iated Signalling CCS Common Channel Signalling CID Channel Identifier CLI Calling Line Identification COT COnTinuity signal CPS Common Part Sub-layer (for AAL) CPT Call Progress Tone Diffserv Differentiated Services DTMF Dual Tone Multi-Frequency EF PHB Expedited Forwarding Per Hop Behaviour GS Guar
42、anteed Service HEC Header Error Control Intserv Integrated Services IP Internet Protocol ISDN Integrated Services Digital Network IWF InterWorking Function LES Loop Emulation Service MTU Maximum Transport Unit OAM Operation, Administration and Maintenance PDU Protocol Data Unit PLC Packet Loss Conce
43、alment 4 ITU-T Rec. Y.1452 (03/2006) PSTN Public Switched Telephone Network QoS Quality of Service RFC Request for Comments ROA Recognized Operating Agency ROHC Robust Header Compression SSCS Service-Specific Convergence Sublayer (of AAL) TDM Time Division Multiplex TFP Termination Flow Point TTL Ti
44、me To Live UDP User Datagram Protocol UUI User-to-User Information VoDSL Voice over DSL VoIP Voice over IP VToIP Voice Trunking over IP 5 Conventions In this Recommendation, the term voice services is synonymous with narrow-band services, and includes 8 kHz digitized audio (carrying voice, telephony
45、 tones, facsimile and modem transmissions, etc.) and optionally may include 16 kHz digitized audio (“wideband speech“), and 64 kbit/s data. In this Recommendation, voice services are considered without regard to the physical interface over which they are provided. In particular, while this physical
46、interface may be a Time Division Multiplex (TDM) link carrying multiple voice-grade channels or an IP link carrying multiple VoIP streams. In this Recommendation, the term “voice trunking“ signifies transport of multiple voice channels using a single IP flow. “VoIP trunking“ refers to the special ca
47、se of transport of multiple VoIP packets using a single IP flow. 6 Voice trunking over IP networks The following figures present the Reference Architecture for voice trunking over IP (VToIP). The functionality described in this Recommendation is implemented in IWFs, which receive multiple voice chan
48、nels, generally from TDM end-systems, from the PSTN/ISDN, or from VoIP connections. The IWFs multiplex the voice channels, and forward them over IP networks. Figure 6-1 depicts voice services originating and terminating in a TDM end-system. This same situation is shown using G.809 2 diagrammatic tec
49、hniques in Figure 6-2. Figure 6-3 depicts the case of VoIP trunking. ITU-T Rec. Y.1452 (03/2006) 5 Figure 6-1/Y.1452 Reference architecture for voice trunking over IP Figure 6-2/Y.1452 Functional architecture for multiplexing P0 channels over IP networks NOTE Figure 6-2 represents one direction of the bidirectional voice session. Figure 6-3/Y.1452 Functional architecture for multiplexing VoIP streams over IP networks 7 General requirements 7.1 User plane requirements For
