1. A path computation method, comprising: receiving concatenation capabilities of each interface of nodes in a network; receiving a path computation request (PCReq) message in a path computation element protocol (PCEP), the PCReq message carrying identifiers of a source node and a destination node that access a client-side service and carrying encoding type, switching type, signal type, concatenation number, and concatenation type, wherein the concatenation number is greater than 1; determining the encoding type is optical channel data unit k (ODUk), the switching type is time division multiplexing (TDM) and the signal type is optical channel data unit 2 (ODU2), when a value of the encoding type is 12, a value of the switching type is 100 and a value of the signal type is 2; determining the encoding type is synchronous digital hierarchy/Synchronous optical network (SDH/SONET), the switching type is TDM and the signal type is VC4, when the value of the encoding type is 5, the value of the switching type is 100 and the value of the signal type is 6; computing a path according to the identifiers of the source node and the destination node that access a client-side service, the encoding type, the switching type, the signal type, the concatenation number, the concatenation type, and the concatenation capabilities; and sending a PCReq response message in the PCEP carrying path information corresponding to the computed path.