Patent ID: 6975586
Filing Date: 2005-12-13
Classification: H04B,H04Q

Abstract:
1. A protection switching method for a passive optical network (PON) system including an optical line terminal for switching between a first active-system transmission/reception section and a first standby-system transmission/reception section by using a switch, a plurality of network units for selectively connecting second active-system transmission/reception sections and second standby-system transmission/reception sections to subscriber terminals upon switching said sections through selectors in the event of a communication abnormality, and transmission paths for star-connecting said second active-system transmission/reception sections to said first active-system transmission/reception section, and also star-connecting said second standby-system transmission/reception sections to said first standby-system transmission/reception section, characterized by comprising the steps of: setting an active-system virtual path and a standby-system virtual path between said optical line terminal and said subscriber terminal in different time slot bands; outputting by said switch a data cell to one of a plurality of ports in the network units, to which said first active-system transmission/reception section and said first standby-system transmission/reception section are connected, in accordance with one of a header value added to the data cell or a time slot of a frame; detecting a communication abnormality in at least one active-system virtual path established between said optical line terminal and said subscriber terminal through said transmission path and said network unit; and upon detection of a communication abnormality in the active-system virtual path, switching by said switch to switch only the transmission paths to establish a standby-system virtual path between said optical line terminal and said subscriber terminal serving as a communication partner, without affecting communication through other active virtual paths in the PON system.