1、INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU CONSTRUCTION, INSTALLATION AND PROTECTION OF CABLES AND OTHER ELEMENTS OF OUTSIDE PLANTS L.17 (O 6/95) IMPLEMENTATION OF CONNECTING CUSTOMERS INTO THE PUBLIC SWITCHED TELEPHONE NETWORK (PSTN) VIA OPTICAL FIBR
2、ES ITU-T Recommendation L.17 (Previously ?CCIlT Recommendation?) ITU-T RECflN*L.17 95 YB62591 Ob02559 Yqq = FOREWORD The ITU-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (IT). The ITU-T is responsible for studying technical, operating
3、 and tariff questions and issuing Recommen- dations 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 IT-T Study Groups which, in their tur
4、n, produce Recommendations on these topics. The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1 (Helsinki, March 1-12, 1993). ITU-T Recommendation L.17 was prepared by ITU-T Study Group 6 (1993-1996) and was approved under the WT
5、SC Resolution No. 1 procedure on the 20th of June 1995. NOTE In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. O 1995 All rights reserved. No part of this publication may be reproduce
6、d or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. Recommendation L.17 IMPLEMENTATION OF CONNECTING CUSTOMERS INTO THE PUBLIC SWITCHED TELEPHONE NETWORK (PSTN) VIA OPTICAL FIBRES (Geneva, 1995) Consid
7、ering the way of connecting customers to the public switched telephone network via optical fibre in order to achieve: (a) improved quality of service: - from stability of network performance during the addition of new services or the reconfiguration of the network; - from a reduced range and complex
8、ity of components tolerant of lower craft skills for commissioning and maintenance; - from the provision of network topologies given in AL. 15; (b) the life of the network; reduced lifetime costs accruing from both initial equipment costs and on-going maintenance costs throughout (c) exploitation of
9、 the flexibility of the existing civil infrastructure developed for copper cables, it is recommended that 1) fibre positions; access by field personnel to plant items associated with individual customer circuits is limited to designated 2) breaks during the predicted fibre lifetime (greater than 20
10、years); the stress induced in fibre of plant items should be limited by the configuration of fibre to ensure no fibre 3) the number of different plant items which could be configured as sub-assembly modules are minimized so that the same modules can be used in the exchange, the customers premises or
11、 in the external field network at flexibility points; 4) without affecting other customers (for example, single circuit management); the packaging of fibres within a module should be controlled to provide stable transmission for each customer 5) fibres within a module should be easily identified; 6)
12、 provide a continuously stable performance during reconfiguration for growth, upgrade, maintenance or recovery; fibre routing mechanisms should ensure the packaging of fibres between the optical cable and the modules 7) disturbing the optical performance of other fibres within the module; sufficient length of fibre tails should be provided to each module for several re-terminations without 8) provision is made within a module to allow interrogation of the module for maintenance purposes. Recommendation L.17 (06/95) 1
