| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent reception failures in a user unit by switching over from a working OLT (optical line terminal) unit to a standby OLT unit without communication interruption. <P>SOLUTION: A control unit (10c) operates the standby OLT unit (10b) in a switchover standby mode. In the switchover standby mode, a memory (30b) stores a down signal of the working OLT unit (10a) not output yet. According to an instruction from the control unit (10c) to shift from the switchover standby mode to a normal mode, a switch (42b) supplies an idle pattern from an idle pattern generator unit (50a) to a drive circuit (44b) for a certain period. With this, ONUs (optical network unit) (22-1 to 22-n) prepares for receiving the down signal output from the stable OLT unit (10b). According to the instruction to shift from the switchover standby mode to the normal mode, the memory (30b) reads out the down signal not output yet to a CPU (38b). <P>COPYRIGHT: (C)2007,JPO&INPIT |
