1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T L.53TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (05/2003) SERIES L: CONSTRUCTION, INSTALLATION AND PROTECTION OF CABLES AND OTHER ELEMENTS OF OUTSIDE PLANT Optical fibre maintenance criteria for access networks ITU-T Recommendation L.53 ITU-T Rec. L.5
2、3 (05/2003) i ITU-T Recommendation L.53 Optical fibre maintenance criteria for access networks Summary This Recommendation deals with optical fibre maintenance criteria for access networks. It describes the fundamental requirements, maintenance section, testing and maintenance items, and methods for
3、 developing a suitable guide to maintaining point-to-multipoint and ring optical networks, respectively. Source ITU-T Recommendation L.53 was approved by ITU-T Study Group 6 (2001-2004) under the ITU-T Recommendation A.8 procedure on 14 May 2003. ii ITU-T Rec. L.53 (05/2003) FOREWORD The Internation
4、al 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 and tariff questions and issuing Recommendations
5、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 Recommendations on these topics. The approval of
6、 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 Recommendation, the expression “Administration“ is
7、 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., interoperability or applicability) and compliance with
8、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 compliance with the Recommendation is required
9、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, validity or applicability of claimed Intellectual
10、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 required to implement this Recommendation. However
11、, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. ITU 2003 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. ITU-
12、T Rec. L.53 (05/2003) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Terms and definitions . 2 4 Abbreviations 2 5 Fundamental requirements 3 5.1 Network topologies 3 5.2 Maintenance section . 4 5.3 Testing and maintenance items 4 6 Testing and maintenance methods 5 6.1 Testing and maintenance method
13、s for point-to-multipoint access networks . 5 6.2 Testing and maintenance methods for ring access networks 6 7 Testing and maintaining wavelength 7 Appendix I Practical solutions for point-to-multipoint access network . 8 I.1 Japanese experience 8 Appendix II Practical solutions for ring access netw
14、ork 12 II.1 Indonesian experience 12 II.2 Japanese experience 15 Appendix III Information of fibre optic water submersion-detecting sensor . 17 III.1 Introduction 17 III.2 Structure of the sensor 18 III.3 Principle of water detection 18 III.4 Characteristics of the sensor. 19 iv ITU-T Rec. L.53 (05/
15、2003) Introduction Recently, networks with several types of topology including the passive optical network (PON) and the ring network using add-drop multiplexers (ADM) have been installed in the field because of the diversification of optical communication services. The point-to-multipoint and ring
16、network architectures are very important in terms of constructing optical fibre networks both effectively and inexpensively. However, the testing and maintenance method used for conventional single star networks (see ITU-T Recs L.25 and L.40) cannot be adapted to these network architectures. Optical
17、 fibre networks have expanded rapidly because of the increase in IP services. In order to test and maintain optical fibre networks effectively, it is necessary to establish identical maintenance criteria for both point-to-multipoint and ring networks. ITU-T Rec. L.53 (05/2003) 1 ITU-T Recommendation
18、 L.53 Optical fibre maintenance criteria for access networks 1 Scope This Recommendation describes the maintenance section, testing and maintenance functions, methods, and criteria for both point-to-multipoint and ring networks in the access network. 2 References The following ITU-T Recommendations
19、and other references contain 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 enc
20、ouraged to investigate the possibility 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 d
21、ocument, the status of a Recommendation. ITU-T Recommendation G.652 (2003), Characteristics of a single-mode optical fibre cable. ITU-T Recommendation G.694.1 (2002), Spectral grids for WDM applications: DWDM frequency grid. ITU-T Recommendation G.694.2 (2002), Spectral grids for WDM applications: C
22、WDM wavelength grid. ITU-T Recommendation G.983.1 (1998), Broadband optical access systems based on Passive Optical Networks (PON). ITU-T Recommendation G.983.2 (2002), ONT management and control interface specification for B-PON. ITU-T Recommendation G.983.3 (2001), A broadband optical access syste
23、m with increased service capability by wavelength allocation. ITU-T Recommendation G.983.4 (2001), A broadband optical access system with increased service capability using Dynamic Bandwidth Assignment (DBA). ITU-T Recommendation G.983.5 (2002), A broadband optical access system with enhanced surviv
24、ability. ITU-T Recommendation G.983.6 (2002), ONT management and control interface specifications for B-PON system with protection features. ITU-T Recommendation G.983.7 (2001), ONT Management and Control Interface specification for Dynamic Bandwidth Assignment (DBA) B-PON system. ITU-T Recommendati
25、on G.983.8 (2003), B-PON OMCI support for IP, ISDN, video, VLAN tagging, VC cross-connections, and other select functions. ITU-T Recommendation G.984.1 (2003), Gigabit-capable Passive Optical Networks (GPON): General characteristics. ITU-T Recommendation L.25 (1996), Optical fibre cable network main
26、tenance. ITU-T Recommendation L.40 (2000), Optical fibre outside plant maintenance support, monitoring and testing system. ITU-T Recommendation L.41 (2000), Maintenance wavelength on fibres carrying signals. 2 ITU-T Rec. L.53 (05/2003) ITU-T Recommendation L.42 (2003), Extending optical fibre soluti
27、ons into the access network. ITU-T Recommendation L.52 (2003), Deployment of Passive Optical Networks (PON). IEC 61746 Ed.1.0 (2001), Calibration of optical time-domain reflectometers (OTDRs). 3 Terms and definitions For the purpose of this Recommendation, the definitions given in ITU-T Recs G.652,
28、G.694.1, G.694.2, G.983.1 to G.983.8, L.25, L.40, L.41, L.42, L.52, and IEC 61746 Ed.1.0 apply. 3.1 access network: A network of optical fibres that extend from a carriers central office into individual homes and businesses, etc. for FTTH, FTTC, and so on. 3.2 point-to-multipoint access network: The
29、 access network accommodating OLT in the central office and several ONUs L.52. 3.3 ring network: A network of loop optical fibres accommodating OLT in central office and ONU in some customer buildings L.42. 3.4 maintenance section: An area of optical fibres that is tested and maintained in an access
30、 network. 3.5 surveillance: To monitor the condition of network elements (NE). Surveillance has two functions: to inform of NE degradation before trouble occurs, and to inform of NE abnormality when trouble occurs L.25, L40. 3.6 control: To restore NE to normal or to take action to maintain service
31、quality L.25, L40. 4 Abbreviations This Recommendation uses the following abbreviations: ADM Add-Drop Multiplexer B-OTDR Brillouin Optical Time Domain Reflectometer CB Customer Building CO Central Office FTTC Fibre to the Curb FTTH Fibre to the Home H-OTDR High spatial resolution Optical Time Domain
32、 Reflectometer ID light Identification light OLT Optical Line Terminal ONU Optical Network Unit OTDR Optical Time Domain Reflectometer PON Passive Optical Network RT Remote Terminal ITU-T Rec. L.53 (05/2003) 3 5 Fundamental requirements 5.1 Network topologies 5.1.1 Point-to-multipoint access network
33、 The basic configuration of a point-to-multipoint access network is shown in Figure 1. Case 1: Indoor splitter in CO; Case 2: Outdoor splitter (passive and active); Case 3: Indoor splitter (passive and active) in CB. 5.1.2 Ring access network The basic configuration of a ring access network is shown
34、 in Figure 2. L.053_F01OLTOLTOLTONUONUONUONUONUONUOptical fibreCase 1: Indoor splitter (passive device) in COCentral office (CO) Customer buildings (CB)Case 2: Outdoor splitter (passive device)or outdoor RT (active node)Case 3: Indoor splitter (passive device)or indoor RT (active node) in CBFigure 1
35、/L.53 Configuration of point-to-multipoint access network L.053_F02ONUOLTONUONUOptical fibreCustomer buildingCustomer buildingCustomer buildingCentral officeFigure 2/L.53 Configuration of ring access network 4 ITU-T Rec. L.53 (05/2003) 5.2 Maintenance section A maintenance section is classified as f
36、ollows: 5.2.1 Maintenance section of point-to-multipoint access network The maintenance sections of the point-to-multipoint access network in Figure 1 are as follows: Case 1: Optical fibre between the OLT and the ONU as shown in Figure 1 case 1. (All sections); Case 2: Optical fibre between the OLT
37、and the ONU as shown in Figure 1 case 2. (All sections); Case 3: Optical fibre between the OLT and the indoor splitter. 5.2.2 Maintenance section of ring access network The maintenance section of the ring access network in Figure 2 consists of all sections of the ring access network. 5.3 Testing and
38、 maintenance items 5.3.1 Testing and maintenance items for point-to-multipoint access networks Maintenance items for point-to-multipoint access networks are classified as shown in Table 1. Table 1/L.53 Testing and maintenance items for point-to-multipoint access networks Category Activity Testing an
39、d maintenance item Status Surveillance (e.g., Periodic testing, Continuous testing) Detection of fibre loss increase Detection of signal power loss increase Detection of water penetration Optional Optional Optional Testing (e.g., Fibre degradation testing) Measurement of fibre fault location Measure
40、ment of fibre strain distribution Measurement of water location Optional Optional Optional Preventative maintenance Control (e.g., Network element control) Fibre identification Fibre transfer Optional Optional Surveillance (e.g., Reception of transmission system alarm or customer trouble report) Ref
41、er to alarm from path operation system Refer to alarm from customer service operation system Optional Optional Testing (e.g., After installation testing, Fibre fault testing) Confirmation of fibre condition Fault identification between transmission equipment and fibre network Measurement of fibre fa
42、ult location Required Required Required After installation before service or post-fault maintenance Control (e.g., Cable install/repair/ replacement) Fibre identification Fibre transfer Storage of outside plant database Information on cable route Required Optional Required Optional ITU-T Rec. L.53 (
43、05/2003) 5 5.3.2 Testing and maintenance items for ring access networks Maintenance items for ring access networks are classified as shown in Table 2. Table 2/L.53 Testing and maintenance items for ring access networks Category Activity Testing and maintenance item Status Surveillance Detection of f
44、ibre loss increase Detection of signal power loss increase Detection of water penetration Optional Optional Optional Testing Measurement of fibre fault location Measurement of fibre strain distribution Measurement of water location Optional Optional Optional Preventative maintenance Control Fibre id
45、entification Fibre transfer Optional Optional Surveillance Refer to alarm from path operation system Refer to alarm from customer service operation system Optional Optional Testing Confirmation of fibre condition Fault identification between transmission equipment and fibre network Measurement of fi
46、bre fault location Required Required Required After installation before service or post-fault maintenance Control Fibre identification Fibre transfer Storage of outside plant database Information on cable route Required Optional Required Optional 6 Testing and maintenance methods There are several w
47、ays to implement these testing and maintenance items. OTDR testing, loss testing, monitoring a proportion of the signal power (power monitoring) and identification light detection are commonly used. The most common methods are described below. 6 ITU-T Rec. L.53 (05/2003) 6.1 Testing and maintenance
48、methods for point-to-multipoint access networks Table 3/L.53 Suitable test methods for point-to-multipoint access networks Category Activity Item Methods Preventative maintenance Surveillance Detection of fibre loss increase Detection of signal power loss increase Detection of water penetration OTDR
49、/loss testing Power monitoring OTDR testing Testing Measurement of fibre fault location Measurement of fibre strain distribution Measurement of water location OTDR testing (Note 1) B-OTDR testing OTDR testing(Note 1) Control Fibre identification Fibre transfer OTDR testing (Note 1)/ID light detecting (Note 2) Switching(Note 3) Surveillance Refer to alarm from path operation system Refer to alarm from customer service operation system On-line/External medium On-line/External medium Testing Confirmation of fibre condition Fault iden
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