Patent ID: 8019220

Claim:
A PON (passive optical network) system including a plurality N (N is a positive integer) of optical splitters, a plurality of house devices set in end users' houses, each said house device connected to one of said N optical splitters, and a station side device (optical line terminator, OLT) including a plurality M+N (M is a positive integer) of PON cards in a PON interface section connected to said house devices via said plurality N of optical splitters, and a concentrating/distributing section for accommodating said plurality N of optical splitters and concentrating and distributing signals via said plurality of PON cards in said interface section, said PON system comprising, in said station side device: M×N optical switch modules connected to an output of said PON interface section for current use among said plurality N of optical splitters, the PON interface section for current use including N of said M+N PON cards designated as current use PON interface cards, and M PON cards in said PON interface section among said plurality M+N of PON cards are allocated to standby in said station side device, realizing an M:N redundancy of said PON cards by connecting said M×N optical switch modules in matrices, such that said M×N optical switch modules permit any one of the M standby PON cards in the PON interface section to selectively be connected to any of the N optical splitters, wherein said station side device causes setting/controlling information of said PON card to be taken over from a PON card in the PON interface section for current use to a standby PON card by adjusting an optical channel delay inside the standby PON card when said optical switch module performs switching.