Patent ID: 6337848
Filing Date: 2002-01-08
Classification: H04J,H04Q

Abstract:
A path switching device for a transmission apparatus comprising a first main signal frame switching unit executing a first frame switching process for each of all or a part of frames in a first transmission signal on a first line to which one or more frames including an area for displaying alarms are multiplexed, a second main signal frame switching unit executing a second frame switching process for each of all or a part of frames in a second transmission signal on a second line to which one or more frames including an area for displaying alarms are multiplexed, and a switching unit selecting an output of either said first main signal frame switching unit or said second main signal frame switching unit in units of said frames and outputting the selected output as a third transmission signal to a third line, a third main signal frame switching unit executing a third frame switching process for each of all or a part of frames in a fourth transmission signal on a fourth line to which one or more frames including an area for displaying alarms are multiplexed, a fourth main signal frame switching unit executing a fourth frame switching process for each of all or a part of frames in the fourth transmission signal on the fourth line, a first service selector unit selecting either an output of said third main signal frame switching unit or an input of the first line in units of said frames and outputting the selected signal to said first line, and a second service selector unit selecting either an output of said fourth main signal frame switching unit or an input of the second line in units of said frames and outputting the selected signal to said second line, further comprising:a first alarm detecting unit detecting each alarm corresponding to each frame contained in the first transmission signal, from the input side of said first transmission signal; a second alarm detecting unit detecting each alarm corresponding to each frame contained in the second transmission signal, from the input side of said second transmission signal; a first alarm switching unit executing a switching process in the same frame order as said first frame switching process, for an alarm of each of said frames output by said first alarm detecting unit; a first comparing unit making said switching unit select an output of either said first main signal frame switching unit or said second main signal frame switching unit in units of said frames by comparing alarms of each of said frames output by the first and second alarm switching units with each other; a third alarm detecting unit detecting each alarm corresponding to each frame contained in the fourth transmission signal, from said fourth transmission signal; a third alarm switching unit executing a switching process in the same frame order as said third frame switching process, for an alarm of each of said frames output by the third alarm detecting unit; a fourth alarm switching unit executing a switching process in the same frame order as said fourth frame switching process, for an alarm of each of said frames output by the third alarm detecting unit; a second comparing unit controlling said first service selector unit by comparing an alarm for each of said frames output by the third alarm switching unit with an alarm for each of said frames detected by said first detecting unit; and a third comparing unit controlling said second service selector unit by comparing an alarm for each of said frames output by the fourth alarm switching unit with an alarm for each of said frames detected by said second alarm detecting unit.