Fault detection method and device

The embodiment of the invention discloses a fault detection method and device, and the method comprises the steps that a source node of a to-be-detected first LSP sends a first message to a destination node through the first LSP, wherein the first message carries the path information of the first LSP, and the first LSP comprises a plurality of LSRs which are sequentially arranged; after receiving the first message, the destination node establishes a second LSP which is reversely shared with the first LSP according to the path information; if so, the destination node can feed back the first BFD message to the source node through the second LSP which is in reverse common path with the destination node, so that the source node can determine the fault condition of the first LSP based on the first BFD message. Therefore, the target node establishes the LSP which is reversely shared with the LSP to be detected on the basis of the path information, so that common-path transmission of the forward BFD message and the