| 摘要 |
A device comprises a plurality of nodes and four optical transmission lines of clockwise and counter-clockwise working operation lines and clockwise and counter-clockwise stand-by lines which connect the nodes in form of a ring. Each node is provided with first and second terminal sections including a receiver and transmitter, with a first optical path switch for switching the optical path between four output terminals of the counter-clockwise working operation and stand-by optical transmission lines, the second terminal section, and output terminal of a first stand-by line, and four input terminals of the clockwise operation and stand-by optical transmission lines, first terminal sections, and a second stand-by line. Each node is also provided with a second optical path switch for switching the optical path between four output terminals of clockwise operation and stand-by optical transmission lines, and first terminal section, and output terminal of the second stand-by path, and four input terminals of the counter-clockwise working operation and stand-by optical transmission lines, second terminal section, and input terminal of the first stand-by path.
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