1、 ETSI TS 102 024-12 V4.1.1 (2003-11) Technical Specification Telecommunications and Internet Protocol Harmonization Over Networks (TIPHON) Release 4; End-to-end Quality of Service in TIPHON Systems; Part 12: IP Telephony Service Availability ETSI ETSI TS 102 024-12 V4.1.1 (2003-11) 2 Reference DTS/T
2、IPHON-05020R4 Keywords availability, IP, QoS, service, telephony, VoIP ETSI 650 Route des Lucioles F-06921 Sophia Antipolis Cedex - FRANCE Tel.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16 Siret N 348 623 562 00017 - NAF 742 C Association but non lucratif enregistre la Sous-Prfecture de Grasse (06) N 7
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5、tatus. Information on the current status of this and other ETSI documents is available at http:/portal.etsi.org/tb/status/status.asp If you find errors in the present document, send your comment to: editoretsi.org Copyright Notification No part may be reproduced except as authorized by written permi
6、ssion. The copyright and the foregoing restriction extend to reproduction in all media. European Telecommunications Standards Institute 2003. All rights reserved. DECTTM, PLUGTESTSTM and UMTSTM are Trade Marks of ETSI registered for the benefit of its Members. TIPHONTMand the TIPHON logo are Trade M
7、arks currently being registered by ETSI for the benefit of its Members. 3GPPTM is a Trade Mark of ETSI registered for the benefit of its Members and of the 3GPP Organizational Partners. ETSI ETSI TS 102 024-12 V4.1.1 (2003-11) 3 Contents Intellectual Property Rights4 Foreword.4 Introduction 5 1 Scop
8、e 6 2 References 6 3 Definitions and abbreviations.7 3.1 Definitions7 3.2 Abbreviations .7 4 Generic IP telephony service performance model7 4.1 Service availability model 8 4.2 Reference Model 8 5 IP packet transfer performance parameters 9 5.1 IP packet Loss Ratio (IPLR).9 5.2 IP Network packet Lo
9、ss Ratio (IPNLR).9 5.3 IP packet Transfer Delay (IPTD) .9 5.4 IP packet Delay Variation (IPDV)9 5.5 IP packet Loss Burst Duration (IPLBD).9 6 IP telephony availability.9 6.1 Availability criteria.9 6.1.1 IP Telephony service availability function .10 6.1.2 IP Connection integrity function.11 6.2 IP
10、Telephony service availability parameters.11 6.2.1 Service Availability (SA)12 6.2.2 Mean Time Between Service Outage (MTBSO) 12 Annex A (informative): Bibliography.13 History 14 ETSI ETSI TS 102 024-12 V4.1.1 (2003-11) 4 Intellectual Property Rights IPRs essential or potentially essential to the pr
11、esent document may have been declared to ETSI. The information pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found in ETSI SR 000 314: “Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
12、respect of ETSI standards“, which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web server (http:/webapp.etsi.org/IPR/home.asp). Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee can be given as to
13、 the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web server) which are, or may be, or may become, essential to the present document. Foreword This Technical Specification (TS) has been produced by ETSI Project Telecommunications and Internet Protocol Harmoni
14、zation Over Networks (TIPHON). The present document is part 12 of a multi-part deliverable covering end-to-end Quality of Service in TIPHON Systems, as identified below: Part 1: “General aspects of Quality of Service (QoS)“; Part 2: “Definition of Speech Quality of Service (QoS) Classes“; Part 3: “S
15、ignalling and Control of end-to-end Quality of Service“; Part 4: “Quality of Service Management“; Part 5: “Quality of Service (QoS) measurement methodologies“; Part 6: “Actual measurements of network and terminal characteristics and performance parameters in TIPHON networks and their influence on vo
16、ice quality“; Part 7: “Design Guide for elements of a TIPHON connection from an end-to-end speech transmission performance point of view“; Part 8: (to be developed during TIPHON Release 5): “QoS multimedia services in TIPHON systems“; Part 9: “Call Performance Classification (Voice)“; Part 10 (to be
17、 developed during TIPHON Release 5): “Requirements for TIPHON Terminals and User Network Aspects“; Part 11: (to be developed during TIPHON Release 5): “Domain by domain performance planning guidelines for end-to-end QoS objectives associated with TIPHON speech QoS classes“; Part 12: “IP Telephony Se
18、rvice Availability“. ETSI ETSI TS 102 024-12 V4.1.1 (2003-11) 5 Introduction The present document forms one of a series of technical reports and technical specifications by Working Group 5 for TIPHON Quality of Service (QoS) classification. The structure of this work is illustrated below in figure 1
19、. Introductions Definitions Explanations Discussions. Definition of the 4 TIPHON classes Measurement methodologies Repository of real results QoS signalling requirements Reporting on QoS Achieved Generic QoS Definitions Specific aspects of TIPHON QoS REPORT SPEC General Aspects of QoS QoS Class Spec
20、 TR 102 024-1 SPEC Measure - ment Methods REPORT Actual Test Results SPEC QoS Control SPEC QoS Manage - ment Useful info for designers TS 102 024-2 TS 102 024-3 TS 102 024-4 TS 102 024-5 TR 102 024-6 REPORT Design Guide - lines TR 102 024-7 Call performance Classification SPEC Call Perf. (voice) TS
21、102 024-9 IP telephony service availability Service Availab ility TS 102 024-12 SPEC Figure 1: TIPHON WG5 QoS Documentation Structure ETSI ETSI TS 102 024-12 V4.1.1 (2003-11) 6 1 Scope The present document defines performance parameters and related criteria in order to specify the Availability perfo
22、rmance of the IP Telephony service. The present document defines Service Availability, as in a multiservice IP network it is useful to define Availability from a service point of view (which can be related to a particular service) rather than from a network perspective. The present document defines
23、performance parameters for determining IP Telephony Service Availability for an established IP Telephony session. The performance parameters refer to IP Packet Transfer as provided by an IP data communication service. The Application Plane issues of service availability are out of the scope of the p
24、resent document. They are addressed in TS 102 024-9 9, where control related parameters have been identified. In the present document the methodology used to define IP Telephony Service Availability is illustrated in detail. Values of performance parameters, if not defined, are for further study. 2
25、References The following documents contain provisions which, through reference in this text, constitute provisions of the present document. References are either specific (identified by date of publication and/or edition number or version number) or non-specific. For a specific reference, subsequent
26、 revisions do not apply. For a non-specific reference, the latest version applies. Referenced documents which are not found to be publicly available in the expected location might be found at http:/docbox.etsi.org/Reference. 1 ITU-T Recommendation I.380 (Y.1540) “Internet protocol data communication
27、 service - IP Packet transfer and availability performance parameters“. 2 Void. 3 ETSI TS 102 024-2: “Telecommunications and Internet Protocol Harmonization Over Networks (TIPHON) Release 4; End-to-end Quality of Service in TIPHON Systems; Part 2: Definition of Speech Quality of Service (QoS) Classe
28、s“. 4 ITU-T Recommendation E.855: “Connection Integrity objective for the international Telephone Service“. 5 ETSI TR 101 300: “Telecommunications and Internet Protocol Harmonization Over Networks (TIPHON); Description of Technical Issues“. 6 Void 7 ETSI TS 102 024-6: “Telecommunication and Internet
29、 Protocol Over Networks (TIPHON); End-to-end Quality of Service in TIPHON System Part 6: Actual measurements of network and terminal characteristics and performance parameters in TIPHON networks and their influence on voice quality“. 8 ITU-T Recommendation D.22 SG13 Geneva, 20-24 November 2000: “Ser
30、vice Availability definition for VoIP“. 9 ETSI TS 102 024-9: “Telecommunication and Internet Protocol Over Networks (TIPHON); End-to-end Quality of Service in TIPHON System Part 9: Call performance Classification“. ETSI ETSI TS 102 024-12 V4.1.1 (2003-11) 7 10 ITU-T Recommendation E.850: “Connection
31、 Retainability Objective for the International Telephone Service“. 11 ITU-T Recommendation E.800: “Terms and definitions related to quality of service and network performance including dependability“. 12 IETF RFC 1889: “RTP: A Transport Protocol for Real-Time Applications“. 3 Definitions and abbrevi
32、ations 3.1 Definitions For the purposes of the present document, the following terms and definitions apply: IP Telephony service: telephony related service that is supported on a managed IP network Population of interest: total set of packets sent from SRC to DST 3.2 Abbreviations For the purposes o
33、f the present document, the following abbreviations apply: CoS Class of Service DST DeSTination IP Internet ProtocolIPDV IP Packet Delay Variation IPLBD IP Packet Loss Burst Duration IPLR IP Packet Loss Ratio IPNLR IP Network packet Loss Ratio IPTD IP Packet Transfer Delay MPs Measurement Points MTB
34、SO Mean Time Between Service Outage PLC Packet Loss Concealment PSTN Public Switched Telephone Network QoS Quality of Service SA Service Availability SRC SouRCe 4 Generic IP telephony service performance model In ITU-T Recommendation E.800 11 the Availability performance is defined as the ability of
35、 an item to be in a state to perform a required function at a given instant of time or at any instant of time within a given time interval. The item can be any part, device, equipment of the network, that can be individually considered and perform a predefined function; it may consist of hardware, s
36、oftware or both: the item may be a switch, a link or a service. The Availability of a multiservice IP network (IP-based network capable of delivering different types of service) can be usefully defined from a service point of view (can be referred to the particular service), thus providing a discuss
37、ion of the concept of service outage based on a given service. EXAMPLE: A 10-second network outage may result in a failure for IP telephone service, but go unnoticed for email. For this reason, in IP-based telecommunications networks, we consider the Service Availability. For the scope of the presen
38、t document the Service Availability requirements for IP Telephony service are analysed. ETSI ETSI TS 102 024-12 V4.1.1 (2003-11) 8 4.1 Service availability model A service is considered to be available when the values of a set of selected performance parameters are deemed acceptable. The value of a
39、specific parameter is deemed acceptable if it is greater (or lower) than of a pre-specified threshold. IP Telephony Service Availability is impacted by the Application plane performance as well as the Transport plane performance: in order to make the telephone service available for the user the call
40、 has first to be actually set up and then (when the call has been established) the packet flow has to be transferred between the end-users. Failure of one or both of these processes heavily impacts the service availability. For the purpose of the present document we consider the IP telephony service
41、 at the Transport Plane level, which is the user information transfer communication function as defined in ITU-T Recommendation I.380 1. Therefore the performance parameters and the relative thresholds, used to determine the service availability, refer to the transfer of IP packet over the IP-based
42、network (see clause5). The Application Plane performance parameters are considered in TS 102 024-9 9. The combination of these IP Packet transfer performance parameters and their thresholds is called the Availability Function. The relation between a performance parameter and the threshold(s) defines
43、 an outage criterion. Every time that an outage criterion is met there is a transition to the unavailable state. The available state is re-entered when all parameters are once again acceptably functioning. The outage criteria are defined considering network performance that falls below TIPHON Narrow
44、band acceptable class. An associated two-state model provides a basis for describing IP telephone service availability (see figure 2). IP TelephonyServiceUnAvailableIP packet Transfer performanceParametersAvailability FunctionsIP TelephonyServiceAvailableFigure 2: Two-state model for Service Availab
45、ility 4.2 Reference Model According to ITU-T Recommendation I.380 1 a generic IP service performance model is defined in order to provide the basis for: identifying the blocks with which the IP Telephony service may be represented; identifying the measurement points to be considered. The model and t
46、he performance parameters defined are independent from the transport technologies (es. ATM, SDH). The Reference Model is defined in TS 102 024-7. ETSI ETSI TS 102 024-12 V4.1.1 (2003-11) 9 5 IP packet transfer performance parameters As indicated in clause 4.1, the IP Telephony service performance pa
47、rameters are defined on the basis of IP packet transfer reference events that may be observed at measurement points (MPs) associated with specified functional and jurisdictional boundaries. This clause defines the set of IP packet transfer performance parameters that could be used to define the IP t
48、elephony service availability. 5.1 IP packet Loss Ratio (IPLR) IP packet loss ratio is the ratio of total lost IP packet outcomes to total transmitted IP packets in a population of interest. A lost packet outcome occurs when: a packet is never delivered or delivered to an unpermitted egress point (I
49、PNLR); a packet is delivered to a permitted egress point out of the specified threshold value for IPTD. IPDV is not compensated by the dejitter buffer (the voice application does not consider packet with jitter more than a fixed threshold). 5.2 IP Network packet Loss Ratio (IPNLR) IP network packet loss ratio is the ratio of total number of never delivered packets and/or packets delivered to an unpermitted egress point to total transmitted IP packets in a population of interest. 5.3 IP packet Transfer Delay (IP
