A transmission apparatus connected to a first transmission apparatus wherein a plurality of physical ports are bundled together as one logical port, and when the output destination of a received frame is a link aggregation port which is this logical port, this frame is forwarded to any physical port of the link aggregation port, and connected to a second transmission apparatus via a communications network which removes redundancy via a first path and second path, the purpose of said transmission apparatus being to forward a frame inputted from said first transmission apparatus to said second transmission apparatus by encapsulation with a label, and forwarding the frame inputted from said second transmission apparatus by decapsulation by removing the label, said transmission apparatus comprising:
- a first interface unit for connecting to the first path;
- a second interface unit for connecting to the second path;
- a third interface unit for connecting to the first physical port of said first transmission apparatus forming the link aggregation port;
- a fourth interface unit for connecting to the second physical port of said first transmission apparatus forming the link aggregation port;
- and
- a switch having a forwarding table wherein identifiers of said first to fourth interface units are stored as output destination information corresponding to the label of the first path and second path, which forwards the frame according to the corresponding output destination information by looking up said forwarding table based on the label of the frame to which a label was assigned,
- wherein said third interface unit has a first storage unit wherein fault detection ACT or SBY is set, and the first storage unit is set to ACT;
- wherein said fourth interface unit has a second storage unit wherein fault detection ACT or SBY is set, and the second storage unit is set to SBY;
- wherein said third interface unit receives a user frame sent from the first physical port of said first transmission apparatus, and forwards the user frame to the second transmission apparatus by encapsulating the user frame with the label of the first path via the first path by said switch;
- wherein said fourth interface unit receives a user frame sent from the second physical port of said first transmission apparatus, and forwards the user frame to the second transmission apparatus by encapsulating the user frame with the label of the first path via the first path by said switch;
- wherein said third interface unit sends a connectivity verification frame to said second transmission apparatus according to said first storage unit which was set to ACT;
- wherein said fourth interface unit does not send a connectivity verification frame to said second transmission apparatus according to said second storage unit which was set to SBY;
- wherein said forwarding table stores at least an identifier of said third interface unit set to ACT as output destination information corresponding to the label in the downstream direction received by said first and second interface units via the first and second paths, and said switch forwards a connectivity verification frame received from said second transmission apparatus by the first path and second path, to said third interface unit according to said forwarding table;
- wherein said third interface unit receives the connectivity verification frame sent at a predetermined interval by said second transmission apparatus, and detects a fault in the first or second paths by detecting that the connectivity verification frame was not received according to said first storage unit set to ACT;
- and
- wherein said fourth interface unit does not detect a fault by detecting that the connectivity verification frame was not received according to said second storage unit which was set to SBY.