1、 International Telecommunication Union ITU-T E.470TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (02/2005) SERIES E: OVERALL NETWORK OPERATION, TELEPHONE SERVICE, SERVICE OPERATION AND HUMAN FACTORS Network management Checking the quality of the international telephone service Operational considera
2、tions for QoS of voice over IP-based networks with PSTN-IP-PSTN architecture ITU-T Recommendation E.470 ITU-T E-SERIES RECOMMENDATIONS OVERALL NETWORK OPERATION, TELEPHONE SERVICE, SERVICE OPERATION AND HUMAN FACTORS INTERNATIONAL OPERATION Definitions E.100E.103 General provisions concerning Admini
3、strations E.104E.119 General provisions concerning users E.120E.139 Operation of international telephone services E.140E.159 Numbering plan of the international telephone service E.160E.169 International routing plan E.170E.179 Tones in national signalling systems E.180E.189 Numbering plan of the in
4、ternational telephone service E.190E.199 Maritime mobile service and public land mobile service E.200E.229 OPERATIONAL PROVISIONS RELATING TO CHARGING AND ACCOUNTING IN THE INTERNATIONAL TELEPHONE SERVICE Charging in the international telephone service E.230E.249 Measuring and recording call duratio
5、ns for accounting purposes E.260E.269 UTILIZATION OF THE INTERNATIONAL TELEPHONE NETWORK FOR NON-TELEPHONY APPLICATIONS General E.300E.319 Phototelegraphy E.320E.329 ISDN PROVISIONS CONCERNING USERS E.330E.349 INTERNATIONAL ROUTING PLAN E.350E.399 NETWORK MANAGEMENT International service statistics
6、E.400E.404 International network management E.405E.419 Checking the quality of the international telephone service E.420E.489 TRAFFIC ENGINEERING Measurement and recording of traffic E.490E.505 Forecasting of traffic E.506E.509 Determination of the number of circuits in manual operation E.510E.519 D
7、etermination of the number of circuits in automatic and semi-automatic operation E.520E.539 Grade of service E.540E.599 Definitions E.600E.649 Traffic engineering for IP-networks E.650E.699 ISDN traffic engineering E.700E.749 Mobile network traffic engineering E.750E.799 QUALITY OF TELECOMMUNICATION
8、 SERVICES: CONCEPTS, MODELS, OBJECTIVES AND DEPENDABILITY PLANNING Terms and definitions related to the quality of telecommunication services E.800E.809 Models for telecommunication services E.810E.844 Objectives for quality of service and related concepts of telecommunication services E.845E.859 Us
9、e of quality of service objectives for planning of telecommunication networks E.860E.879 Field data collection and evaluation on the performance of equipment, networks and services E.880E.899 For further details, please refer to the list of ITU-T Recommendations. ITU-T Rec. E.470 (02/2005) i ITU-T R
10、ecommendation E.470 Operational considerations for QoS of voice over IP-based networks with PSTN-IP-PSTN architecture Summary It is recognized that IP-based networks are increasingly used to deliver voice services to customers. These networks can impact the end-to-end service quality perceived by us
11、ers. In order to maintain network performance required to deliver the desired service quality, several operational issues have to be considered. These issues include defining network performance measures and their objectives, interworking issues between networks employing a variety of technologies,
12、network measurement points, information to be exchanged between network operators, etc. ITU-T Study Group 13 on “Next-generation networks“ has defined four key scenarios to be considered in their IP framework document: Scenario a: A voice call from an IP terminal connected to an IP-based network to
13、a PSTN phone; Scenario b: A voice call from a PSTN phone to an IP terminal connected to an IP-based network; Scenario c: A voice call from a PSTN phone to another PSTN phone via an IP-based network; Scenario d: A voice call from an IP terminal connected to an IP-based network to another IP terminal
14、connected to an IP-based network via PSTN. This Recommendation focuses only on Scenario c. In Scenario c, both ends are PSTN (telephone) terminals and connected to PSTN at least as a local access (PSTN-IP-PSTN architecture). This network architecture is employed or planned to be employed by many ROA
15、s all over the world. In this case, the user may not be aware of the changes in the underlying technology and the QoS expectations may be expected to remain the same. This Recommendation is for providing the general aspects of voice services in PSTN-IP-PSTN architecture, especially, for providing in
16、formation whether or not the existing ITU-T Recommendations could be applicable to PSTN-IP-PSTN voice architecture. Also, it covers the general impacts of IP networks to voice services and provides an overview of the performance measurement/management scope. Source ITU-T Recommendation E.470 was app
17、roved on 24 February 2005 by ITU-T Study Group 2 (2005-2008) under the WTSA Resolution 1 procedure. ii ITU-T Rec. E.470 (02/2005) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardiz
18、ation 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 (WTSA), which m
19、eets 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 fall within ITU-T
20、s 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 Recommendation i
21、s 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 such as “must“ a
22、nd 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 Recommendation may in
23、volve 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 approval of this Re
24、commendation, ITU had 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 consult the TSB patent database
25、. ITU 2005 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. E.470 (02/2005) iii CONTENTS Page 1 Scope 1 2 References. 2 3 Reference architectures for PSTN-IP-PSTN voice service 3 4. QoS framework. 4 5
26、 QoS categorization and applicability 4 5.1 Connection quality 4 5.2 Call clarity 5 6 IP network impacts . 5 7 QoS measurement and management of PSTN-IP-PSTN architecture 6 8 Further study. 8 ITU-T Rec. E.470 (02/2005) 1 ITU-T Recommendation E.470 Operational considerations for QoS of voice over IP-
27、based networks with PSTN-IP-PSTN architecture 1 Scope It is recognized that IP-based networks are increasingly used to deliver voice services to customers. These networks can impact the end-to-end service quality perceived by users. In order to maintain network performance required to deliver the de
28、sired service quality, several operational issues have to be considered. These issues include defining network performance measures and their objectives, interworking issues between networks employing a variety of technologies, network measurement points, information to be exchanged between network
29、operators, etc. ITU-T Study Group 13 on “Next-generation networks“ has defined four key scenarios to be considered in their IP framework document: Scenario a: A voice call from an IP terminal connected to an IP-based network to a PSTN phone; Scenario b: A voice call from a PSTN phone to an IP termin
30、al connected to an IP-based network; Scenario c: A voice call from a PSTN phone to another PSTN phone via an IP-based network; Scenario d: A voice call from an IP terminal connected to an IP-based network to another IP terminal connected to an IP-based network via PSTN. This Recommendation focuses o
31、nly on Scenario c. In Scenario c, both ends are PSTN (telephone) terminals and connected to PSTN at least as a local access (PSTN-IP-PSTN architecture). This network architecture is employed or planned to be employed by many ROAs all over the world. In this case, the user may not be aware of the cha
32、nges in the underlying technology and the QoS expectations may be expected to remain the same. This Recommendation is for providing the general aspects of voice services in PSTN-IP-PSTN architecture, especially, for providing information whether or not the existing ITU-T Recommendations could be app
33、licable to PSTN-IP-PSTN voice architecture. Also, it covers the general impacts of IP networks to voice services and provides an overview of the performance measurement/management scope. The outline of this Recommendation is as follows. Clause 2 presents the normative references. In order to resolve
34、 operational issues, a reference architecture is presented in clause 3. In clause 4, the QoS framework is discussed along with the network performance and QoS parameter which were already defined by ITU-T Study Group 2 on “Operational aspects of service provision, networks and performance“, Study Gr
35、oup 12 on “Performance and quality of service“ and Study Group 13 that apply to the PSTN-IP-PSTN scenario. Clause 5 discusses key network performance parameters that are usually defined in the E-series Recommendations and identifies new parameters that may need to be defined. In clause 6, IP network
36、 impacts to voice services are discussed. Clause 7 describes QoS measurement and management sections with related issues. Lastly, in clause 8, several issues for further study are pointed out. 2 ITU-T Rec. E.470 (02/2005) 2 References The following ITU-T Recommendations and other references contain
37、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 subject to revision; users of this Recommendation are therefore encouraged to investigate the po
38、ssibility 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 document within this Recommendation does not give it, as a stand-alone document, the status of a Reco
39、mmendation. ITU-T Recommendation E.425 (2002), Internal automatic observations. ITU-T Recommendation E.428 (1992), Connection retention. ITU-T Recommendation E.430 (1992), Quality of service framework. ITU-T Recommendation E.431 (1992), Service quality assessment for connection set-up and release de
40、lays. ITU-T Recommendation E.434 (1992), Subscriber-to-subscriber measurement of the public switched telephone network. ITU-T Recommendation E.437 (1999), Comparative metrics for network performance management. ITU-T Recommendation G.177 (1999), Transmission planning for voiceband services over hybr
41、id Internet/PSTN connections. ITU-T Recommendation G.1000 (2001), Communications Quality of Service: A framework and definitions. ITU-T Recommendation G.1010 (2001), End-user multimedia QoS Categories. ITU-T Recommendation H.323 (2003), Packet-based multimedia communications systems. ITU-T Recommend
42、ation I.350 (1993), General aspects of quality of service and network performance in digital networks, including ISDNs. ITU-T Recommendation P.561 (2002), In-service, non-intrusive measurement device voice service measurements. ITU-T Recommendation P.562 (2004), Analysis and interpretation of INMD v
43、oice-service measurements. ITU-T Recommendation P.862 (2001), Perceptual evaluation of speech quality (PESQ): An objective method for end-to-end speech quality assessment of narrow-band telephone networks and speech codecs. ITU-T Recommendation Y.1530 (2004), Call processing performance for voice se
44、rvice in hybrid IP networks. ITU-T Recommendation Y.1540 (2002), Internet protocol data communication service IP packet transfer and availability performance parameters. ITU-T Recommendation Y.1541 (2002), Network performance objectives for IP-based services. ITU-T Rec. E.470 (02/2005) 3 3 Reference
45、 architectures for PSTN-IP-PSTN voice service A basic reference architecture of PSTN-IP-PSTN VoIP services could be as in Figure 1. Its difference from the existing PSTN for voice service is the addition of Interworking Function Block between PSTN and IP-based network (IWFB) to the existing PSTN arc
46、hitecture. This Interworking Function Block between PSTN and IP-based network: interworks between PSTN and IP-based network; is an essential part for voice services of PSTN-IP-PSTN architecture; is composed of Media Gateway Controller, Media Gateway and IP-based network. Figure 1/E.470 General confi
47、guration of PSTN-IP-PSTN voice service The elements in Figure 1 are as follows: PSTN terminal: PSTN telephone; PSTN clouds: Domestic and/or International Exchanges would be included; IP-based Network clouds: Internet Protocol based network; Media Gateway: Media conversion gateway between PSTN and IP
48、 network; Media Gateway Controller: Controller for Media gateway; Media Gateway Control Protocol: Control protocol for media gateway (e.g., H.323, SIP, MGCP, Megaco/H.248). NOTE 1 Figure 1 shows the generic architecture for interworking of PSTN and IP technologies. So, there could be more than one I
49、P-based network cloud. The figure does not attempt to show ownership of network domains. NOTE 2 In Figure 1, there is no attempt to show a product-specific or vendor-specific name. NOTE 3 The interworking between circuit-switched signalling and IP signalling on the availability of features and the ability to accurately determine call disposition could be done by the Media Gateway control protocol and the SIGTRAN protocol. Another view of PSTN-IP-PSTN architecture could be as
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