Delay measurement method and station

A first station, comprising:

• a controller;
• an optical path selector connected to the controller;
• and
• a fiber interface unit connected to the optical path selector;
• wherein the controller is configured to control the optical path selector to work in a first state, the fiber interface unit is configured to select a first fiber to send a first optical supervisory channel (OSC) signal to a second station, wherein the first OSC signal comprises a first time stamp, and the first time stamp indicates a first sending moment at which the first station sends the first OSC signal,
• wherein the controller is further configured to control the optical path selector to work in a second state, the fiber interface unit is configured to select the first fiber to receive a second OSC signal from the second station at a second receiving moment, wherein the second OSC signal comprises a second time stamp, the second time stamp indicates a first receiving moment at which the second station receives the first OSC signal and a second sending moment at which the second station sends the second OSC signal, and a difference between a value of a wavelength used by the first OSC signal and a value of a wavelength used by the second OSC signal is less than a preset value, and
• wherein the controller is further configured to calculate a unidirectional transmission delay between the first station and the second station based on the first sending moment, the first receiving moment, the second sending moment, and the second receiving moment.

A second station, comprising:

• a controller;
• an optical path selector connected to the controller;
• and
• a fiber interface unit connected to the optical path selector;
• wherein the controller is configured to control the optical path selector to work in a first state, the fiber interface unit is configured to select a first fiber to receive a first optical supervisory channel (OSC) signal from a first station, wherein the first OSC signal comprises a first time stamp, and the first time stamp indicates a first sending moment at which the first station sends the first OSC signal, and
• wherein the controller is further configured to control the optical path selector to work in a second state, the fiber interface unit is configured to select the first fiber to send a second OSC signal to the first station, wherein the second OSC signal comprises a second time stamp, the second time stamp indicates a first receiving moment at which the second station receives the first OSC signal and a second sending moment at which the second station sends the second OSC signal, and a difference between a value of a wavelength used by the first OSC signal and a value of a wavelength used by the second OSC signal is less than a preset value.