1、INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU E.671 (03/2000) SERIES E: OVERALL NETWORK OPERATION, TELEPHONE SERVICE, SERVICE OPERATION AND HUMAN FACTORS Quality of service, network management and traffic engineering - Traffic engineering - Definitions P
2、ost-selection delay in PSTN/ISDN networks using Internet telephony for a portion of the connection ITU-T Recommendation E.671 (Formely CCITT Recommendation) ITU-T E-SERIES RECOMMENDATIONS OVERALL NETWORK OPERATION, TELEPHONE SERVICE, SERVICE OPERATION AND HUMAN FACTORS OPERA TION, NUMBERING, ROUTING
3、 AND MOBILE SERVICES INTERNATIONAL OPERATION Definitions General provisions concerning Administrations General provisions concerning users Operation of international telephone services Numbering plan of the international telephone service International routing plan Tones in national signalling syste
4、ms Numbering plan of the international telephone service Maritime mobile service and public land mobile service OPERATIONAL PROVISIONS RELATING TO CHARGING AND ACCOUNTING IN THE INTERNATIONAL TELEPHONE SERVICE Charging in the international telephone service Measuring and recording call durations for
5、 accounting purposes UTILIZATION OF THE INTERNATIONAL TELEPHONE NETWORK FOR NON- TE LEP H ONY AP PLI CATI ONS General Phototelegraphy International routing plan QUALITY OF SERVICE, NETWORK MANAGEMENT AND TRAFFIC ENGINEERING NETWORK MANAGEMENT ISDN PROVISIONS CONCERNING USERS International service st
6、atistics International network management Checking the quality of the international telephone service TRAFFIC ENGINEERING Measurement and recording of traffic Forecasting of traffic Determination of the number of circuits in manual operation Determination of the number of circuits in automatic and s
7、emi-automatic operation Grade of service Definitions ISDN traffic engineering Mobile network traffic engineering QUALITY OF TELECOMMUNICATION SERVICES: CONCEPTS, MODELS, OBJECTIVES AND DEPENDABILITY PLANNING Terms and definitions related to the quality of telecommunication services Models for teleco
8、mmunication services Objectives for quality of service and related concepts of telecommunication services Use of quality of service objectives for planning of telecommunication networks Field data collection and evaluation on the performance of equipment, networks and services E. 1 00-E. 103 E.104-E
9、.119 E. 120-E. 139 E. 140-E. 159 E. 160-E. 169 E. 170-E. 179 E. 180-E. 189 E. 190-E. 199 E.200-E.229 E.230-E.249 E.260-E.269 E.300-E.319 E.320-E.329 E.350-E.399 E.400-E.409 E.41 0-E.419 E.420-E.489 E.490-E.505 E.506-E509 E.510-E519 E.520-E539 E.540-E599 E.700-E.749 E.750-E.799 E.800-E.809 E.810-E.84
10、4 E.845-E.859 E.860-E.879 E.880-E.899 For further details, please rer to the list of ITD-T Recommendations. ITU-T RECOMMENDATION E.671 POST-SELECTION DELAY IN PSTNDSDN NETWORKS USING INTERNET TELEPHONY FOR A PORTION OF THE CONNECTION Summary This Recommendation proposes a post-selection delay Grade
11、of Service (GOS) parameter and target values when part of a PSTN/ISDN connection is replaced by Internet Protocol (IP) based network(s). This parameter is defined and their target values specified assuming that the network and the network components are fully operational. Also, only point-to-point c
12、onnections supporting basic call flows are considered in this release of the Recommendation. Source ITU-T Recommendation E.671 was prepared by ITU-T Study Group 2 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on 13 March 2000. Recommendation E.671 (03/2000) 1 FOREWORD ITU (I
13、nternational Telecommunication Union) is the United Nations Specialized Agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the ITU. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Rec
14、ommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these to
15、pics. The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with IS0 and IEC. NOTE In this Rec
16、ommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. INTELLECTUAL PROPERTY RIGHTS The ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve t
17、he use of a claimed Intellectual Property Right. The 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 Recom
18、mendation, the 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 databas
19、e. o ITU 2000 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing fi-om the ITU. 11 Recommendation E.671 (03/2000) CONTENTS 1 2 3 4 4.1 4.2 4.3 Scope
20、. References . Abbreviations Post-selection delay GOS . GOS concepts . Definitions Target values . Reference connections GOS objectives . History . Recommendation E.671 (03/2000) Page 1 . 111 Recommendation E.671 POST-SELECTION DELAY IN PSTNDSDN NETWORKS USING INTERNET TELEPHONY FOR A PORTION OF THE
21、 CONNECTION (Geneva, 2000) 1 Scope This Recommendation proposes a post-selection delay Grade of Service (GOS) parameter and target values when part of a PSTN/ISDN connection is replaced by Internet Protocol (IP) based network(s). This parameter is defined and their target values specified assuming t
22、hat the network and the network components are fully operational. Also, only point-to-point connections supporting basic call flows are considered in this release of the Recommendation. NOTE 1 - Other GOS parameters such as answer-signal delay, call-release delay, and probability of end-to- end bloc
23、king, require further study. NOTE 2 - This release of the Recommendation is concerned only with the case of transparent service, i.e. users will not be aware of the fact that a portion of the circuit-switched connection is being replaced by P telephony. When this is not the case, P telephony may be
24、used to facilitate the offering of a set of service classes with different qualities of service. This subject requires further study. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommen
25、dation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other refer
26、ences listed below. A list of the currently valid ITU-T Recommendations is regularly published. - - ITU-T Recommendation ES00 (1 998), Trafic intensity measurement principles. CCITT Recommendation ES40 (1988), Overall grade of service of the internationalpart of an international connection. - CCITT
27、Recommendation ES41 (1988), Overall grade of service for international connections (subscriber-to-subscriber). ITU-T Recommendation E.65 1 (2000), Reference connections for trafic engineering of IP access networks. - - ITU-T Recommendation E.72 1 (1 999), Network grade of service parameters and targ
28、et values for circuit-switched services in the evolving ISDN. ITU-T Recommendation E.771 (1996), Network grade of service parameters and target values for circuit-switched land mobile services. ITU-T Draft Recommendation Y. 123 1, IP access network architecture. ITU-T Draft Recommendation Y. 1530, C
29、all processing performance for voice service in hybrid IP networks. Recommendation E.671 (03/2000) 1 3 Abbreviations This Recommendation uses the following abbreviations: GOS Grade of Service IP Internet Protocol ISDN Integrated Services Digital Network PSTN Public Switched Telephone Network TE Term
30、inal Equipment VOIP Voice Over Internet Protocol 4 Post-selection delay GOS 4.1 GOS concepts GOS parameters were developed for traditional circuit-switched PSTN and standards set in Recommendations ES40 and E.541. GOS concepts were refined and new standards set in the context of circuit-switched ser
31、vices on ISDN. The new standards are given in Recommendations E.720 and E.72 1. This Recommendation is based on the concepts, parameter definitions, and service types given in Recommendation E.72 1. 4.2 Definitions The following two definitions of “post-selection delay“, as specified in Recommendati
32、on E.72 1, are reproduced herein for ease of reference. 4.2.1 post-selection delay (overlap sending) is defined as the time interval rom the instant the first bit of the INFORMATION message containing the last selection digit is passed by the calling terminal to the access signalling system until th
33、e last bit of the first message indicating call disposition is received by the calling terminal (ALERTING message in case of successful call). 4.2.2 post-selection delay (en bloc sending) is defined as the time interval rom the instant the first bit of the initial SETUP message containing all the se
34、lection digits is passed by the calling terminal to the access signalling system until the last bit of the first message indicating call disposition is received by the calling terminal (ALERTING message in case of successful call). NOTE - In case of automatic answering terminals, the ALERTING messag
35、e is replaced by the CONNECT message. 4.3 Target values When IP-based networks are used to substitute for a portion of the circuit-switched PSTN/ISDN connection, users will expect and network providers should meet comparable end-to-end post-selection delay as is encountered on connections provided e
36、ntirely on PSTN/ISDNs. Refinement of the target values which are provisionally specified herein is for further study. NOTE - If and when P telephony is used to provide a set of service classes with different qualities of service, the services so provided will not be transparent to the user in the se
37、nse of Note 2, in clause 1. In this case, the target values for the respective service classes will necessarily be different from the ones specified in this Recommendation. 2 Recommendation E.671 (03/2000) 5 Reference connections This Recommendation is concerned with the class of PSTAOOISDN-to-PSTAO
38、/ISDN via IP reference connections as specified in 6.2.3/E.65 1. It is reproduced in Figure 1. VOIP IP core TE I 4 “,“lr PSTN/ISDN 1-1 TE I U U T0207910-99 Figure 1E.671- PSTNDSDN-to-PSTNDSDN connection via IP The IP core network “cloud“ in the diagram is also commonly referred to as the “IP backbon
39、e“. It provides wide-area coverage and interconnection between domains. As specified in Draft Recommendation Y.1231, the IP core network may include one or more IP service provider networks. The Voice Over IP (VOIP) gateway is responsible for the translation and handling of voice calls between PSTN/
40、ISDN and IP core network. For this class of reference connections, there are three cases of interest for which separate standards for the IP portion of an overall connection can be set. These are: o Connection type I: IP as a national network where the IP-based network replaces a national PSTN/ISDN
41、in a long-distance connection. o Connection type 2: IP as an international network where the IP-based network replaces the international portion of an international connection. There are three subcases: a) The PSTN/ISDNs at both the originating and terminating ends are not replaced by an IP-based ne
42、twork; b) The PSTN/ISDN at the originating end is replaced by an IP-based network; c) The PSTN/ISDN at the terminating end is replaced by an IP-based network. Connection type 3: IP as an end-to-end network where the IP-based network replaces both the national and international portions of an interna
43、tional connection. o Recommendation E.671 (03/2000) 3 These three types of reference connections are given in Figure 2. For connection type 2, only subcase a) is shown in the figure. loat H0 National IP Network VOIP VOIP o o National/International Local switch Local switch Connection type 1 : Nation
44、al IP network o o Local switch Local switch Connection type 2: International IP network T0207920-99 Connection type 3: NationaVinternational IP network Figure 2E.671- Reference connections 4 Recommendation E.671 (03/2000) 6 GOS objectives The target values for the post-selection delay parameter for
45、the above three types of reference connections are given in Table 1. Reference connection National IF network (equivalent to E.721 toll) International IF network Normal load High load Mean 95% Mean 95% 5.0 s 8.0 s 7.5 s 12.0 s FFS FFS FFS FFS Nationalhternational IF network (equivalent to E.72 1 international) 7 History This is the first issue of Recommendation E.67 1. 8.0 s 11.0 s 12.0 s 16.5 s Recommendation E.671 (03/2000) 5
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