Patent ID: 8670849

Claim:
A digital signal switching apparatus inputs digital signals of two or more systems, each digital signal having a format of adding, status information formed as a block from a plurality of frames, and the digital signal switching apparatus outputs the input digital signals processed by switching processing, comprising: means for retrieving blocks of the status information from the digital signal on which the switching processing was performed, the digital signal without the status information being directly output by the retrieving means; means for storing one or more blocks of the status information retrieved by the retrieving means; and means for adding again, to the digital signal directly output from the retrieving means, the status information from the storing means by the block order to a position of the status information in a frame of the digital signal on which switching processing was performed by the digital signal switching apparatus, wherein when the digital signal is one of not input and suddenly stopped, the status information is continuously output from the storage means.