A method for monitoring performance of a wavelength path, comprising: receiving (S101a), by a second node, a path request message of a wavelength path from an upstream neighboring node, wherein the path request message comprises at least a path identifier of the wavelength path and second wavelength identifier information; obtaining (S102a), by the second node, a wavelength identifier according to the second wavelength identifier information, and recording a mapping relationship between the wavelength path and the wavelength identifier; and determining (S103a), by the second node according to the wavelength identifier, a low frequency signal modulated at a working wavelength of the wavelength path, and obtaining performance of the wavelength path by monitoring the low frequency signal; wherein: the second wavelength identifier information is information constructed according to the wavelength identifier and comprised in a path request message of the wavelength path sent to a downstream neighboring node by a first node after recording the mapping relationship between the wavelength path and the wavelength identifier; the wavelength identifier is obtained by the first node according to first wavelength identifier information in a control reply message sent from a centralized control node; the wavelength identifier is indicated by a frequency value of the low frequency signal and a binary code representing a modulation scheme and is used by the first node to determine the low frequency signal modulated at the working wavelength of the wavelength path and the modulation scheme and modulate the working wavelength of the wavelength path; the first wavelength identifier information is information constructed according to the wavelength identifier and comprised in the control reply message sent to the first node by the centralized control node after allocating, according to wavelength identifier allocation request information, the wavelength identifier that identifies the wavelength path; and the wavelength identifier allocation request information is carried in a control request message received by the centralized control node from the first node. receiving (S101a), by a second node, a path request message of a wavelength path from an upstream neighboring node, wherein the path request message comprises at least a path identifier of the wavelength path and second wavelength identifier information; obtaining (S102a), by the second node, a wavelength identifier according to the second wavelength identifier information, and recording a mapping relationship between the wavelength path and the wavelength identifier; and determining (S103a), by the second node according to the wavelength identifier, a low frequency signal modulated at a working wavelength of the wavelength path, and obtaining performance of the wavelength path by monitoring the low frequency signal; wherein: the second wavelength identifier information is information constructed according to the wavelength identifier and comprised in a path request message of the wavelength path sent to a downstream neighboring node by a first node after recording the mapping relationship between the wavelength path and the wavelength identifier; the wavelength identifier is obtained by the first node according to first wavelength identifier information in a control reply message sent from a centralized control node; the wavelength identifier is indicated by a frequency value of the low frequency signal and a binary code representing a modulation scheme and is used by the first node to determine the low frequency signal modulated at the working wavelength of the wavelength path and the modulation scheme and modulate the working wavelength of the wavelength path; the first wavelength identifier information is information constructed according to the wavelength identifier and comprised in the control reply message sent to the first node by the centralized control node after allocating, according to wavelength identifier allocation request information, the wavelength identifier that identifies the wavelength path; and the wavelength identifier allocation request information is carried in a control request message received by the centralized control node from the first node. the second wavelength identifier information is information constructed according to the wavelength identifier and comprised in a path request message of the wavelength path sent to a downstream neighboring node by a first node after recording the mapping relationship between the wavelength path and the wavelength identifier; the wavelength identifier is obtained by the first node according to first wavelength identifier information in a control reply message sent from a centralized control node; the wavelength identifier is indicated by a frequency value of the low frequency signal and a binary code representing a modulation scheme and is used by the first node to determine the low frequency signal modulated at the working wavelength of the wavelength path and the modulation scheme and modulate the working wavelength of the wavelength path; the first wavelength identifier information is information constructed according to the wavelength identifier and comprised in the control reply message sent to the first node by the centralized control node after allocating, according to wavelength identifier allocation request information, the wavelength identifier that identifies the wavelength path; and the wavelength identifier allocation request information is carried in a control request message received by the centralized control node from the first node.