Method, device and system for establishing a label switched path in the fast switching rerouting

A communication system, comprising: a first computer network, configured to: send a first message to a second network device on a path label switching, LSP, wherein the first message carries information maintenance state renewal way, the first message a notification message so that the second network device determines a time of maintaining the state of renewal path, according to state information maintenance renewal path of the first message; and send a second message, after sending the first message, the second computer network time keeping the state of renewal of the road, where the second message carries information renewal of the road, being the information carried in the second message error information or information LSP LSP establishment, so that the second network device establishes a LSP according to the information renewal road conditions of the second message; and the second computer network, configured to: receive the first message sent by the first computer network, wherein the first message carries information maintenance renewal status of the road; determine the maintenance time of renewal state road, according to state information maintenance renewal path of the first message; receiving the second message sent by the first network equipment, maintenance time renewal state road, where the second message carries information renewal road conditions; and set the LSP according to the information renewal road conditions of the second message.