ITU-T approves standards for fiber closures

Study Group 6 of the International Telecommunication Union (ITU-T) has produced Recommendations L.13 and L.51, which form the first international performance standards for fiber-optic closures. These global standards can be used as a tool for generating performance specifications for sealed optical closures. Preparation of these standards was directed by Chris Radelet (Tyco Electronics OSP, Belgium), with close cooperation from the International Electrotechnical Commission. The standards will allow network operators to benchmark optical-node products worldwide and should simplify conformance testing and the process of tendering and ordering. The standards give special attention to network stability and future adaptability.

L.51 contains the general principles for generating performance requirements for passive optical nodes and describes the product and performance parameters necessary to characterize a node. It describes environmental classes and installation conditions as well as circuit separation and transient losses during network maintenance activities. The Recommendation also summarizes the general requirements that are applicable for all types of passive nodes throughout the optical network.

L.13, focusing on sealed optical closures for outside plant, has been revised according to L.51. It deals with the design of the closure housing as well as the optical-fiber organizer, taking into account mechanical and environmental characteristics as well as the characteristics of the organizer. The Recommendation provides a complete performance specification and test plan. The user can select the applicable installation environment, the desired level of optical stability, and a level of circuit separation. It is also possible to modify the basic environmental test settings according to specific local needs by specifying additional requirements.

A similar ITU-T Recommendation on the performance of optical distribution frames should be ready by year's end. Amendments have also been made to Recommendations G.652 and G.655 on fibers and cables for compatibility with L.13.

Stephen C. Mettler, recently retired from Bell Laboratories and an independent consultant on outside plant and other fiber-optic communications issues, represents OFS as chairman of ITU's Working Party 2/6 in Study Group 6. He can be reached at 404-262-1867 or

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