Transmission path switching apparatus

摘要

Only when data inputted from first and second transmission paths agree with each other, a selector effects switching from the data from the first transmission path to the data from the second transmission path or from the data from the second transmission path to the data from the first transmission path. A transmission interface adds an overhead to the data of a payload outputted from the selector. A counter counts up at the timing of an overhead in the data inputted from the first transmission path based on an output signal from a multiframe synchronizing circuit that is associated with the first transmission path. In the absence of uninterrupted data switching by the selector, a parity bit is inserted into a random pattern generated by a random pattern generator, and the random pattern with the inserted parity bit is written into a memory while the counter is counting up.