1、INTERNATIONAL TELECOMMUNICATION UNION ITU=T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU G.911 (04197) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital transmission systems - Digital sections and digital line system - Parameters for optical fibre cable systems Parame
2、ters and calculation methodologies for reliability and availability of fibre optic systems ITU-T Recommendation G.91 I (Previously CCITT Recommendation) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services STD-ITU-T RECMN G.91L-ENGL 1997 =
3、LiBb2591 Obq02b9 403 = ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS INTERNATIONAL ANALOGUE CARRIER SYSTEM G. 100-G.199 GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER- TRANSM ISS1 ON SYSTEMS SYSTEM
4、S ON METALLIC LINES G.200-G.299 INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE G.300-G.399 GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION G.400-G ,449 WITH METALLIC LINES COORDINATION OF RADIOTELEPHONY AND LINE
5、TELEPHONY G.450-G.499 TRANSMISSION MEDIA CHARACTERISTICS G.600-G.699 DIGITAL TRANSMISSION SYSTEMS TERMINAL EQUIPMENTS G.70O-G.799 DIGITAL NETWORKS G. 800-G. 899 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.900-G.999 General G.900-G.909 Digital sections at hierarchical bit rates based on a bit rate of
6、2048 kbiVs G. 9204.929 Digital line transmission systems on cable at non-hierarchical bit rates G.930-G.939 Digital line systems provided by FDM transmission bearers G.940-G. 949 Digital line systems G.950-G.959 Digital section and digital transmission systems for customer access to ISDN G.960-G. 96
7、9 Optical fibre submarine cable systems G.970-G.979 G.9804.999 Optical line systems for local and access networks For further details, please refir to ITU-T List of Recommendations. COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services STD-I
8、TU-T RECMN G-711-ENGL 1777 m Lib2591 b40270 125 ITU-T RECOMMENDATION 6.911 PARAMETERS AND CALCULATION METHODOLOGIES FOR RELIABILITY AND AVAILABILITY OF FIBRE OPTIC SYSTEMS Summary This Recommendation identifies a minimum set of parameters necessary to characterize the reliability and availability of
9、 fibre optic systems. Different parameters are given for system reliability and maintenance, for active optic device reliability, for passive optical device reliability, and for optical fibre and cable reliability. This Recommendation also provides guidelines and methods for calculating the predicte
10、d reliability of devices, units and systems. Examples are included. Source ITU-T Recommendation G.911 was revised by ITU-T Study Group 15 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on the 8th of April 1997. COPYRIGHT International Telecommunications Union/ITU Telecommunic
11、ationsLicensed by Information Handling ServicesSTD-ITU-T RECMN G-911-ENGL 1997 = 4Bb2591 Ob40271 Ob1 FOREWORD ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommunications. The IT Telecommunication Standardization Sector (IT-T) is a permanent
12、 organ of the IT. The IT-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 Conference (WTSC), which meets every four years, esta
13、blishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. The approval of Recommendations by the Members of the IT-T is covered by the procedure laid down in WTSC Resolution No. 1. In some areas of information technology which fall within I
14、T-Ts purview, the necessary standards are prepared on a collaborative basis with IS0 and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. INTELLECTUAL PROPERTY RIGHTS The I
15、T draws attention to the possibility that the practice or implementation of this Recommendation may involve the 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
16、members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, the ITU hadhad not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that
17、this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. O IT 1997 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, wit
18、hout permission in writing from the ITU. ii Recommendation 6.911 (04/97) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services1 2 2. 1 2.2 2.3 2.4 3 4 4.1 4.2 4.3 4.4 5 5.1 5.2 5.3 5.4 5.5 6 6.1 CONTENTS Page Introduction Parameters related
19、to reliability and availability of fibre optic systems . Fibre optic system availability and maintenance reliability-related parameters Active optical device reliability parameters . Passive optical device reliability parameters Optical fibre and cable reliability parameters . Definitions Steady-sta
20、te reliability prediction method of devices. units and fibre optic systems in serial configuration . Purpose and scope Applications of the predicted failure rate method 4.2.1 Equipment manufacturers/suppliers 4.2.2 Equipment owners and network operators Guidelines . 4.3,l Definition of failure . 4.3
21、.2 Operating conditions . 4.3.3 Environmental description Adjusting the estimates given by this method . Steady-state failure rate prediction method Applicability of the method . Device steady-state failure rate (ksi) . Unit steady-state failure rate (As) Line system steady-state failure rate (AsYs)
22、 4.3.4 4.4.1 4.4.2 4.4.3 4.4.4 Calculation methodologies for fibre optic system devices, units and systems in serial configuration regarding reliability and maintenance parameters., Plug-in circuit pack MTBF . System MTBF (terminal and repeater) . Frequency of scheduled maintenance actions Random fa
23、ilure rate Infant mortality factor . Calculation methodology of availability and maintenance parameters of fibre optic systems with line protection . General considerations . Line protection and network protection . 1 1 1 2 2 3 3 5 5 5 6 6 6 6 6 6 6 7 7 7 7 7 8 8 9 9 9 10 10 10 . Recommendation 6.91
24、1 (04/97) 111 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services6.2 6.3 7 8 8.1 8.2 STD-ITU-T RECMN G-911-ENGL 1997 m 48b259L b40273 934 = Page State-space methodology to determine availability and maintenance parameters in 6.2.1 6.2.2 6.
25、2.3 fibre optic systems with line protection Step 1 - Inputs . Step 2 - From the above inputs determine Step 3 - Calculating system reliability-related measures Options of fibre systems with line protection . One-for-one (1 + 1) link protection . One-for4 (N + 1) link protection . 6.3.1 6.3.2 6.3.3
26、Rings . Reference circuits for end-to-end channel availability of line systems on optical fibres . Allocation methodology for end-to-end unavailability objectives . Contributors to unavailability - Considerations regarding SDH and PDH systems on optical fibres Allocation methodology . Appendix I . D
27、etermination of unit steady-state failure rate . Example I . 1 Unit description (example) . 1.2 1.3 Reliability parameters of devices (example) Unit steady-state failure rate (FITS) Appendix II . Study case channel availability for a 4 x 140 Mbits repeater link on optical fibres with “3 + 1“ line pr
28、otection II . 1 Description . Results - Unavailability (minutes/year) per 140 Mitis channel . 11.2 Appendix III . Study case . Channel availability for a point-to-point fibre connection in the local network with 1 + 1 I line protection, with and without cable-path redundancy III . 1 Description . Na
29、ture of the problem . Type of connections 111.1.1 III . 1.2 111.2 Results 10 10 11 14 14 14 15 15 15 17 17 17 20 20 20 20 21 21 22 23 23 23 24 26 iv Recommendation G.911 (04/97) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesRecommenda
30、tion G.911 Repair rates (input) Architecture and models of line protection (input) PARAMETERS AND CALCULATION METHODOLOGIES FOR RELIABILITY AND AVAILABILITY OF FIBRE OPTIC SYSTEMS (revised in 1997) 1 Introduction This Recommendation provides details of the parameters needed to characterize and the p
31、rocedures to predict and calculate fibre optic system reliability, including reliability of the devices and availability of channels transmitted through the systems. The emphasis is on single-mode fibre systems (see Figure 1). Results Results - Failure rates -Mean time to repair t Study case in Appe
32、ndix I Methodology regarding reliability-related measures of elements and systems in serial configuration Clauses 4 and 5 T - End-to-end channel/ system availability -Frequency actions of repair - Cost of maintenance estimates Study cases in Appendices II and III i configuration T1506460-90 Figure U
33、G.911- How to use Recommendation G.911 2 Parameters related to reliability and availability of fibre optic systems 2.1 This subclause gives the system service parameters and system maintenance parameters. The values may be provided in study cases and are for further study. It is anticipated, however
34、, that different Fibre optic system availability and maintenance reliability-related parameters Recommendation G.911 (04/97) 1 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesSTD-ITU-T RECMN G-SLL-ENGL 2997 9 48b2572 Ob40275 707 9 Syste
35、m service parameter parameters/values may be required for the various system applications, including point-to-point long/medium distance, local networks, etc. (see Tables 1 and 2). Units Table UG.911 Operation system interface availability Midyr unavailability I Mean system availability“) Random fai
36、lure rate Infant mortality factor I Midyr unavailability Events per year Dimensionless 1 Wear-out failure rate at 1 O years (Alo) Wear-out failure rate at 20 years (ho) Wear-out activation energy (E,) I Mean channel availability I Midyr unavailability per channel I FITs FITs eV Table 2/6.911 System
37、service parameter I System MTBF (such as terminals, repeaters and media) Plug-in circuit pack MTBF“ Frequency of scheduled maintenance actions Y ears I Years I Events per year I MTBF (mean time between failures) “) In order to estimate the quantity of spares required. 2.2 This subclause includes rel
38、iability parameters for Characterizing active fibre optic devices such as lasers, LEDs and detectors. The values may be provided in study cases and are for further study (see Table 3). Active optical device reliability parameters Table 3/G.911 I Active optical device reliability parameter 1 Units 1
39、I Median Life (ML) I Years I Standard deviation (o) -I- I Random (steady-state) failure rate (Ar) I FITs 1 I Random failure activation energy (E,) I eV I 2.3 This subclause includes the necessary reliability parameters for characterizing passive fibre optic devices such as connectors, splices and sp
40、litters. Identification of the parameters and their values are for Mer study (see Table 4). Passive optical device reliability parameters 2 Recommendation G.911 (04/97) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services STD-ITU-T RECMN G*
41、SLL-ENGL 1777 LiBb259L Ob11027b by3 Passive optical device reliability parameter Units 2.4 This subclause includes the necessary reliability parameters for characterizing installed optical fibres and cables. These parameters distinguish extrinsic failure modes and intrinsic failure modes. Extrinsic
42、failure modes, such as cable dig-ups or installatiodmaintenance errors, dominate the overall reliability. Intrinsic modes, such as fibre fatigue or cable degradation, are typically only a small fraction of total reliability. Clarification of these modes, extrinsic versus intrinsic, in actual cases i
43、s under study. Assessment or prediction methods are also under study (see Table 5). Optical fibre and cable reliability parameters Optical fibre and cable reliability parameter Extrinsic mode failure rate Table WG.911 Units FITskable-km Intrinsic mode cable failure rate Intrinsic mode fibre failure
44、rate FITdcable-km FITdfibre-km 3 Definitions This clause includes definitions for the reliability parameters for characterizing fibre optic systems and device reliability. 3.1 item; entity (such as a system or a channel): Any part, device, sub-system, functional unit, equipment or system that can be
45、 individually considered. 3.2 constant failure rate period: That possible period in the life of a non-repaired item during which the failure rate is approximately constant. NOTE - In any particular case it is necessary to explain what is meant “by approximately constant“. 3.3 availability performanc
46、e: The ability of 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, assuming that the external resources, if required, are provided. NOTE 1 -This ability depends on the combined aspects of the reliability perfor
47、mance, the maintainability performance and the maintenance support performance of an item. NOTE 2 - In the definition of the item, the external resources required must be delineated. NOTE 3 - The term availability is used as an availability performance measure. 3.4 of time, t. 3.5 interval (ti, t2).
48、 3.6 instantaneous availability: The probability that an item is in an up-state at a given instant mean availability: The normalized integral of the instantaneous availability in a given time mean time between failures (MTBF): The expectation of the time between failures. 3 Recommendation G.911 (041
49、97) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services STD*ITU-T RECMN G.7LL-ENGL 1777 48b257L Ubi0277 58T D 3.7 early failure period (infant mortality): That possible early period in the life of an item, beginning at a given instant of time and during which the instantaneous failure intensity for a repaired item or the instantaneous failure rate for a non-repaired item decreases rapidly. NOTE - In any particular case, it is necessary to explain what is meant by “decreases r
