A protection switching method, wherein the method comprises: when a fault occurs on a working path between a first end node and a second end node, sending, by the first end node, a first protection switching request message to an intermediate node, wherein a protection path of the working path comprises the first end node, the second end node, and at least one intermediate node; and receiving, by the first end node, a second protection switching request message from the intermediate node, and switching service data to the protection path for transmission, wherein: one overhead frame of each of the first protection switching request message and the second protection switching request message comprises at least two overhead information groups, and each of the two overhead information groups comprises a request type field, a request signal identifier field, and a bridge flag field, wherein the request type field indicates a fault type of the working path, the request signal identifier field indicates a service identifier of a service that requests a protection resource, the bridge flag field indicates whether the protection resource corresponding to the service identifier indicated by the request signal identifier field has been bridged, and the bridge flag field occupies 1 bit, wherein each of the two overhead information groups further comprises a request flag field, wherein the request flag field is used to indicate whether the service corresponding to the service identifier indicated by the request signal identifier field requests the protection resource. when a fault occurs on a working path between a first end node and a second end node, sending, by the first end node, a first protection switching request message to an intermediate node, wherein a protection path of the working path comprises the first end node, the second end node, and at least one intermediate node; and receiving, by the first end node, a second protection switching request message from the intermediate node, and switching service data to the protection path for transmission, wherein: one overhead frame of each of the first protection switching request message and the second protection switching request message comprises at least two overhead information groups, and each of the two overhead information groups comprises a request type field, a request signal identifier field, and a bridge flag field, wherein the request type field indicates a fault type of the working path, the request signal identifier field indicates a service identifier of a service that requests a protection resource, the bridge flag field indicates whether the protection resource corresponding to the service identifier indicated by the request signal identifier field has been bridged, and the bridge flag field occupies 1 bit, wherein each of the two overhead information groups further comprises a request flag field, wherein the request flag field is used to indicate whether the service corresponding to the service identifier indicated by the request signal identifier field requests the protection resource. one overhead frame of each of the first protection switching request message and the second protection switching request message comprises at least two overhead information groups, and each of the two overhead information groups comprises a request type field, a request signal identifier field, and a bridge flag field, wherein the request type field indicates a fault type of the working path, the request signal identifier field indicates a service identifier of a service that requests a protection resource, the bridge flag field indicates whether the protection resource corresponding to the service identifier indicated by the request signal identifier field has been bridged, and the bridge flag field occupies 1 bit, wherein each of the two overhead information groups further comprises a request flag field, wherein the request flag field is used to indicate whether the service corresponding to the service identifier indicated by the request signal identifier field requests the protection resource.