WO2018218511A1 - 时延测量方法及站点 - Google Patents

时延测量方法及站点 Download PDF

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Publication number
WO2018218511A1
WO2018218511A1 PCT/CN2017/086619 CN2017086619W WO2018218511A1 WO 2018218511 A1 WO2018218511 A1 WO 2018218511A1 CN 2017086619 W CN2017086619 W CN 2017086619W WO 2018218511 A1 WO2018218511 A1 WO 2018218511A1
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WO
WIPO (PCT)
Prior art keywords
station
osc signal
time
optical
optical path
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Application number
PCT/CN2017/086619
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English (en)
French (fr)
Inventor
李邦旭
Original Assignee
华为技术有限公司
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Publication date
Application filed by 华为技术有限公司 filed Critical 华为技术有限公司
Priority to CN201780077328.5A priority Critical patent/CN110100397B/zh
Priority to PCT/CN2017/086619 priority patent/WO2018218511A1/zh
Publication of WO2018218511A1 publication Critical patent/WO2018218511A1/zh
Priority to US16/696,755 priority patent/US20200099444A1/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
    • H04B10/075—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal
    • H04B10/077—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal using a supervisory or additional signal
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
    • H04B10/075—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal
    • H04B10/077—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal using a supervisory or additional signal
    • H04B10/0775—Performance monitoring and measurement of transmission parameters
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
    • H04B10/075—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal
    • H04B10/079—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal using measurements of the data signal
    • H04B10/0795—Performance monitoring; Measurement of transmission parameters
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0005—Switch and router aspects
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0062—Network aspects
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0005—Switch and router aspects
    • H04Q2011/0037—Operation
    • H04Q2011/0045—Synchronisation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0062—Network aspects
    • H04Q2011/0073—Provisions for forwarding or routing, e.g. lookup tables
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
    • H04Q2213/13172—Supervisory signals

Definitions

  • the present application relates to the field of optical communication technologies, and in particular, to a time delay measurement method and a station.
  • DWDM dense wavelength division multiplexing
  • C-BAND C-band optical signal
  • OSC optical supervisory channel
  • the prior art uses a "single fiber bidirectional" method to measure the one-way transmission delay between stations, thereby performing time synchronization.
  • the OSC signal is transmitted back and forth in the same optical fiber 1, and the transmission delay of the optical signal can be calculated.
  • the time stamp transmission diagram shown in FIG. 2 calculates a one-way transmission delay according to time stamp information by using time stamp information between two stations transmitted in the OSC channel.
  • the A site transmits at a wavelength of 1491 nm and the B site transmits at a wavelength of 1511 nm.
  • the delay of the two wavelength transmissions is not equal due to the dispersion of the optical fiber (when the long fiber type is G.652 and the length is 80 km, the transmission delay difference is 27 ns). A half of the sum of the delays will produce an error of 13 ns and cannot be compensated.
  • the present application provides a time delay measurement method and a station to accurately measure a one-way transmission delay between stations.
  • An aspect of the present application provides a time delay measurement method, including: a first station controls an optical path selector to operate in a first state, so that the first station selects a first optical fiber to send a first optical monitoring to a second station.
  • Channel OSC signal the first OSC signal includes a first timestamp, the first timestamp indicating a first sending moment of the first station sending the first OSC signal; the first station controlling the optical path
  • the selector operates in a second state, such that the first station selects the first optical fiber to receive a second OSC signal from a second station at a second receiving time, the second OSC signal including a second timestamp,
  • the second timestamp indicates that the second station receives the first receiving moment of the first OSC signal, and the second station sends the second sending moment of the second OSC signal; the first OSC signal and the The difference between the wavelength values used by the second OSC signal is less than a preset range; the first station calculates the first station according to the first sending time, the first receiving time
  • the optical path is switched by the optical path selector so that the time stamp is included.
  • the two OSC signals are transmitted in the same fiber whose wavelength values are smaller than the preset range, so that the one-way transmission delay between the two stations can be accurately measured according to the time stamp.
  • the method further includes: the first station receiving an acknowledgement message from the second site, The confirmation message is used to indicate that the second station receives the first OSC signal.
  • the second station after receiving the first OSC signal, the second station sends an acknowledgement message to the first station to confirm that the first OSC signal is received, so that the first station can accurately switch the optical path.
  • the first station may also perform switching of the optical path after a preset time of transmitting the first OSC signal.
  • the first station calculates a single order between the first station and the second station according to the first sending moment, the first receiving moment, the second sending moment, and the second receiving moment. After the transmission delay, the method further includes: the first station sending the one-way transmission delay to the second station. In this implementation manner, after the first station calculates the one-way transmission delay, the first station sends a one-way transmission delay to the second station, so that the second station can accurately accurately according to the one-way transmission delay and the time of the first station. Time synchronization.
  • the method further includes: the first station sending a third OSC signal to the second station
  • the third OSC signal includes an updated time of the first station.
  • the first station periodically sends the updated time of the first station, and the second station can implement time synchronization with the first station according to the updated time of the first station and the one-way transmission delay.
  • a delay measurement method including: the second station controls an optical path selector to operate in a first state, so that the second station selects a first optical fiber from the first site Receiving a first optical monitoring channel OSC signal, where the first OSC signal includes a first timestamp, the first timestamp indicating a first sending moment of the first station sending the first OSC signal; the second The station controls the optical path selector to operate in a second state, to cause the second station to select the first optical fiber to send a second OSC signal to the first station, where the second OSC signal includes a second timestamp, The second timestamp indicates that the second station receives the first receiving moment of the first OSC signal, and the second station sends the second sending moment of the second OSC signal; the first OSC signal The difference between the wavelength values used by the second OSC signal is less than a preset range.
  • the optical path is switched by the optical path selector, so that the two OSC signals including the time stamp are transmitted in the same optical fiber whose wavelength value is smaller than the preset range, so that the time stamp can be accurately measured according to the time stamp.
  • the method further includes: the second station sending an acknowledgement message to the first station, where The confirmation message is used to indicate that the second station receives the first OSC signal.
  • the second station after receiving the first OSC signal, the second station sends an acknowledgement message to the first station to confirm that the first OSC signal is received, so that the first station can accurately switch the optical path.
  • the first station may also perform switching of the optical path after a preset time of transmitting the first OSC signal.
  • the second station controls the optical path selector to operate in the second state, including: the second station controls the optical path selector to work according to a change in optical power in the first optical fiber.
  • the first station does not need to notify the change of the optical path of the second station, and when the first station switches the state of the optical path selector, the second station can switch the optical path selector of the second station according to the change of the optical power in the optical fiber. status. With Body, the fiber has no light and the optical power is zero.
  • the method further includes: receiving, by the second station, the first station One-way transmission delay.
  • the first station calculates the one-way transmission delay
  • the first station sends a one-way transmission delay to the second station, and the second station can perform time synchronization according to the one-way transmission delay and the time of the first station.
  • the method further includes: the second station according to the one-way transmission delay and the first The time of the second station synchronizes the time of the second station with the time of the first station.
  • the second station can accurately perform time synchronization according to the one-way transmission delay and the time of the first station.
  • the method further includes: the second station receiving the third OSC signal sent by the first station And the third OSC signal includes an updated time of the first station; the second station updates the time of the second station according to the updated time of the first station and the one-way transmission delay .
  • the first station periodically sends the updated time of the first station, and the second station can accurately implement the time synchronization with the first station according to the updated time of the first station and the one-way transmission delay.
  • the difference between the wavelength values used by the first OSC signal and the second OSC signal is zero.
  • the difference between the wavelength values used by the two OSC signals is zero, so that the measured one-way transmission delay is completely error-free.
  • the one-way transmission delay is a half of a difference between a first operational value and a second operational value, wherein the first operational value
  • the difference between the second receiving time and the first sending time is the difference between the second sending time and the first receiving time.
  • the one-way transmission delay is calculated based on the time at which the two stations recorded in the timestamp respectively transmit and receive the OSC signal.
  • the optical path selector is a 2x2 optical switch.
  • switching of the two optical paths can be easily achieved by a 2x2 optical switch.
  • a site having functionality to implement site behavior in the above method.
  • the functions may be implemented by hardware or by corresponding software implemented by hardware.
  • the hardware or software includes one or more modules corresponding to the functions described above.
  • the station includes: an optical path control unit, configured to control the optical path selector to operate in the first state; and a sending unit, configured to select the first optical fiber to send the first optical monitoring channel OSC signal to the second station
  • the first OSC signal includes a first timestamp, the first timestamp indicating a first sending time that the first station sends the first OSC signal
  • the optical path control unit is further configured to control the The optical path selector operates in the second state
  • the receiving unit is configured to select the first optical fiber to receive the second OSC signal from the second station at the second receiving time, the second OSC signal includes a second timestamp, the a second timestamp indicating a first receiving time at which the second station receives the first OSC signal, and a second sending time at which the second station sends the second OSC signal
  • the first OSC signal and the The difference between the wavelength values used by the second OSC signal is less than a preset range
  • the calculating unit is configured to calculate the first station according to the first sending time, the first receiving
  • the site includes: a controller, an optical path selector connected to the controller, and an optical interface unit connected to the optical path selector; wherein: the controller is configured to: Controlling the optical path selector to operate in a first state, wherein the optical interface unit selects the first optical fiber to send a first optical monitoring channel OSC signal to the second station, where the first OSC signal includes a first timestamp, The first timestamp indicates a first sending moment of the first station sending the first OSC signal; the controller is further configured to control the optical path selector to operate in a second state, so that the optical interface unit is in the first Receiving, by the receiving time, the first optical fiber, receiving, by the second station, a second OSC signal, where the second OSC signal includes a second timestamp, the second timestamp indicating that the second station receives the first a first receiving moment of the OSC signal, and a second sending moment of the second OSC signal sent by the second station; a difference between wavelength values used by the first OSC signal and the second
  • the principle and the beneficial effects of the device can be referred to the method embodiments of the foregoing possible sites and the beneficial effects thereof. Therefore, the implementation of the device can refer to the implementation of the method, and the repetition is no longer Narration.
  • a site having functionality to implement site behavior in the above method.
  • the functions may be implemented by hardware or by corresponding software implemented by hardware.
  • the hardware or software includes one or more modules corresponding to the functions described above.
  • the station includes: an optical path control unit, configured to control the optical path selector to operate in a first state; and a receiving unit, configured to select, by the first optical fiber, the first optical monitoring channel from the first station
  • An OSC signal the first OSC signal includes a first timestamp, the first timestamp indicating a first sending moment of the first OSC signal sent by the first station
  • the optical path control unit is further configured to control The optical path selector operates in a second state
  • the sending unit is configured to select the first optical fiber to send a second OSC signal to the first station, and the second OSC signal includes a second timestamp, the second a timestamp indicating a first reception time at which the second station receives the first OSC signal, and a second transmission time at which the second station transmits the second OSC signal
  • the first OSC signal and the first The difference between the wavelength values used by the two OSC signals is less than the preset range.
  • the site includes: a controller, an optical path selector connected to the controller, and an optical interface unit connected to the optical path selector; wherein: the controller is configured to: Controlling the optical path selector to operate in a first state, such that the optical interface unit selects the first optical fiber to receive a first optical monitoring channel OSC signal from the first station, the first OSC signal including a first timestamp, The first timestamp indicates that the first station sends the first sending moment of the first OSC signal; the controller is further configured to control the optical path selector to operate in the second state, so that the optical interface unit Selecting the first optical fiber to send a second OSC signal to the first station, the second OSC signal includes a second timestamp, the second timestamp indicating that the second station receives the first of the first OSC signal a receiving time, and a second sending time at which the second station sends the second OSC signal; a difference between wavelength values used by the first OSC signal and the second OSC signal is less than a preset range.
  • the principle and the beneficial effects of the device can be referred to the method embodiments of the foregoing possible sites and the beneficial effects thereof. Therefore, the implementation of the device can refer to the implementation of the method. The details are not repeated here.
  • Yet another aspect of the present application provides a computer readable storage medium having instructions stored therein that, when executed on a computer, cause the computer to perform the methods described in the above aspects.
  • Yet another aspect of the present application provides a communication chip in which instructions are stored that, when run on a network device or terminal device, cause the computer to perform the methods described in the various aspects above.
  • Yet another aspect of the present application provides a computer program product comprising instructions which, when run on a computer, cause the computer to perform the methods described in the various aspects above.
  • FIG. 1 is a schematic structural diagram of a prior art optical transmission network networking
  • FIG. 2 is a schematic diagram of a prior art time stamp transmission
  • FIG. 3 is a schematic structural diagram of networking of an optical transmission network according to an embodiment of the present disclosure.
  • FIG. 4 is a schematic structural diagram of an optical transport network device according to an embodiment of the present disclosure.
  • FIG. 5 is a schematic diagram of an operation state of an optical switch according to an embodiment of the present invention.
  • FIG. 6 is a schematic structural diagram of another optical transmission network according to an embodiment of the present disclosure.
  • FIG. 7 is an interaction flowchart of a time delay measurement method according to an embodiment of the present invention.
  • FIG. 8 is a schematic diagram of time stamp transmission according to an embodiment of the present invention.
  • FIG. 9 is a schematic structural diagram of another optical transmission network networking according to an embodiment of the present disclosure.
  • FIG. 10 is a schematic diagram of an OTN frame format according to an embodiment of the present disclosure.
  • FIG. 11 is a schematic diagram of an interaction process of another time delay measurement method according to an embodiment of the present disclosure.
  • FIG. 12 is a schematic structural diagram of a station according to an embodiment of the present invention.
  • FIG. 13 is a schematic structural diagram of another station according to an embodiment of the present invention.
  • FIG. 3 is a schematic diagram of a networking structure of an optical transmission network according to an embodiment of the present invention, illustrating a first station (the station A in the figure) and a second station (the station B in the figure).
  • the optical communication structure, Site A and Site B may be OTN devices.
  • the general structure of the OTN device is shown in Figure 4.
  • the OTN device 100 includes a tributary board 1, a cross board 2, and a circuit board 3.
  • the direction of transmission of the service can be from the customer side to the line side, and also from the line side to the customer side.
  • the service sent or received by the client side is called the client side service, and the service received or sent by the line side is called the wavelength division side service.
  • the service processing flow in the two directions is a reverse process.
  • the client side to the line side direction is taken as an example for description:
  • the tributary board 1 completes the package mapping of the customer service.
  • Customer services include multiple service types, such as packet services and constant bit rate (CBR) services.
  • the packet service may include an Ethernet media access control (MAC) packet service, a flexible Ethernet (FlexE) packet service, a multiprotocol label switching (MPLS) packet service, and an internet protocol (internetwork protocol). , IP) messages, etc.
  • the cbr service may include a synchronous digital hierarchy (SDH) service, an OTN service, a common public radio interface (CPRI) service, or other time division multiplexing (TDM) type services.
  • SDH synchronous digital hierarchy
  • OTN an OTN service
  • CPRI common public radio interface
  • TDM time division multiplexing
  • the tributary board 1 is configured to receive client services from the client side, map the received client service package to an optical data unit (ODU) signal, and add a corresponding OTN management monitoring overhead.
  • ODU optical data unit
  • the ODU signal may be ODUflex, ODU0, ODU1, ODU2, ODU2e, ODU3, ODU4, etc.
  • the OTN management monitoring overhead may be an ODU overhead.
  • Different types of customer services can be packaged into different ODU signals in different ways.
  • the cross board 2 completes the full cross connection of the branch board and the circuit board to realize flexible cross scheduling of the ODU signal.
  • the cross board can realize the transmission of the ODU signal from any one of the tributary boards to any one of the circuit boards, or the OTU signal can be transmitted from any one of the circuit boards to any one of the circuit boards, and the customer signal can be transmitted from any one of the tributary boards. Transfer to any of the tributary boards.
  • the circuit board 3 forms an optical transport unit (OTU) signal and transmits it to the line side. Before the ODU signal forms an OTU signal, the circuit board 3 can multiplex multiple multiplexed ODU signals with relatively low rates into the ODU signals with higher relative rates.
  • the corresponding OTN management monitoring overhead is added to the ODU signal to form an OTU signal and sent to the optical transmission channel on the line side.
  • the ODU signal may be ODU1, ODU2, ODU3, ODU4, ODUCn, etc.
  • the OTU signal (which may or may not be multiplexed) may be OTU1, OTU2, OTU3, OTU4, ODUCn, and the like.
  • the OTN management monitoring overhead can be an OTU overhead.
  • the line side service signal passes through the OM or OD, and then amplified by an optical amplifier (OA) and transmitted through a fiber interface unit (FIU).
  • OA optical amplifier
  • FOU fiber interface unit
  • the OSC signal generated by the OSC unit is transmitted through the FIU.
  • the device for performing OSC signal transmission in each station may include a controller, a small form-factor pluggables (SFP), an optical path selector, and an optical interface unit sequentially connected to the controller.
  • the controller is an electrical chip, responsible for inserting and extracting the time stamp signal, and finally sending/receiving the 155M electrical signal of the OSC channel, which is the total control chip of other components in the station.
  • the controller is an FPGA chip.
  • the SFP is a photoelectric conversion module that receives an electrical signal from the controller, performs electro-optical conversion internally, and sends out an electrical signal. At the same time, it receives the optical signal, performs internal-to-electrical conversion, and sends an electrical signal.
  • the SFP can also be equipped with an optical time domain reflectometer (OTDR).
  • OTD optical time domain reflectometer
  • the SFP in station A is connected to the FIU through a first optical path selector
  • the SFP in station B is connected to the FIU through a second optical path selector.
  • the first/second optical path selector is operative to select an optical path in accordance with a control command.
  • This embodiment adopts the "single fiber unidirectional" optical communication mode. As shown in FIG. 3, the optical signal is transmitted from the station A to the station B through the optical fiber 1, and the optical signal fed back from the station B is transmitted from the optical fiber 2 to the station A. Thus, there is no case where the signal transmitted by the station A in the prior art is mixed with the signal transmitted from the station B when passing through the combiner.
  • the first optical path selector in the station A and the second optical path selector in the station B are a 2 ⁇ 2 optical switch, and the switching of the two optical paths can be easily realized by the 2 ⁇ 2 optical switch.
  • the 2 ⁇ 2 optical switch is a four-port optical device, and the 2 ⁇ 2 optical switch can operate in two states, and the state is switched by the controller.
  • FIG. 5 is a schematic diagram showing the working state of the optical switch according to the embodiment of the present invention. In the left diagram of FIG. 5, the state of the optical switch is 1, the port A is connected to the port C, and the port B is connected to the port D; In the right figure, it is state 2 of the optical switch, port A is connected to port D, and port B is connected to port C.
  • a combine/demultiplexer is used to merge/separate the OSC signal from the C-BAND signal.
  • Combined / The splitter can be either FIU or SFIU.
  • the site B may further include a clock synchronization circuit connected to the controller for implementing clock synchronization with the site A.
  • the networking structure of another optical transmission network provided by the embodiment of the present invention as shown in FIG. 6 may be optical switch not connected to the optical fiber 2, which is a half-double. If the unidirectional transmission delay of the optical fiber 2 is measured, the optical switch may not be connected to the optical fiber 1.
  • FIG. 7 is an interaction flowchart of a time delay measurement method according to an embodiment of the present invention, which is applied to time delay measurement between two stations.
  • the method can include the following steps:
  • the first station controls the first optical path selector to operate in the first state.
  • the second station controls the second optical path selector to operate in the first state.
  • the first station selects a first optical fiber to send a first OSC signal to a second station, where the first OSC signal includes a first timestamp, and the first timestst indicates that the first station sends the first The first transmission time of the OSC signal.
  • the first station controls the first optical path selector to operate in a second state.
  • the second station controls the second optical path selector to operate in a second state.
  • the second station selects the first optical fiber to send a second OSC signal to the first station, where the second OSC signal includes a second timestamp, and the second timestamp indicates that the second station receives a first reception time of the first OSC signal, and a second transmission time of the second OSC signal sent by the second station; a difference between wavelength values used by the first OSC signal and the second OSC signal Less than the preset range.
  • the first station calculates a one-way transmission delay between the first station and the second station according to the first sending time, the first receiving time, the second sending time, and the second receiving time.
  • the controller of each station controls the optical switch to operate in state 1 (as shown by the solid line of the optical switch in Fig. 5).
  • the controllers of station A and station B send and receive OSC signals to establish OSC communication. Meanwhile, since station A and station B are serially transmitted, station B uses a clock synchronization circuit to extract clocks in OSC signals to implement station B and Site A's clock is synchronized.
  • step S102 station A transmits a first OSC signal to station B, and station B receives the first OSC signal.
  • the first OSC signal is transmitted by the station A to the station B via the optical fiber 1.
  • the first OSC signal comprises a first time stamp
  • the first stamp comprises a first transmitting station A transmits a first timing signal T 1 A.
  • the station B When receiving the first OSC signal, the station B records the first receiving time T 1 B, and saves T 1 B into the second time stamp, and then camps the second time stamp.
  • step S103 the station A switching optical switch operates in state 2, and then, as shown in step S104, the station B also switches the optical switch to operate in state 2.
  • station B adds a transmission time T 2 B to the second timestamp that resides, and transmits a second OSC signal to station A, the second OSC signal including a second timestamp.
  • the controller of the site B uses the optical switch of the second OSC signal (such as the optical switch of the station B in FIG. 9 ).
  • the dotted line is transmitted through fiber 1 to station A, which transmits the received second OSC signal to the controller of station A by an optical switch (shown by the dashed line of the optical switch of station A in FIG. 9).
  • the second timestamp includes a first reception time T 1 B and a second transmission time T 2 B.
  • the second time stamp may also further include a first transmission time T 1 A.
  • the station A calculates the space between the station A and the station B according to the first transmission time T 1 A, the first reception time T 1 B, the second transmission time T 2 B, and the second reception time T 2 A.
  • One-way transmission delay D is a half of a difference between the first operation value and the second operation value, wherein the first operation value is a difference between the second reception time and the first transmission time. a value, the second operation value being a difference between the second transmission time and the first reception time.
  • the one-way transmission delay D (T 2 AT 1 A - (T 2 BT 1 B)) / 2, wherein the first operational value (T 2 AT 1 A) is a time stamp in the optical fiber 1 The total time of the round-trip transmission, the second operational value (T 2 BT 1 B) is the time at which the time stamp resides in Site B.
  • the difference between the wavelength values used by the first OSC signal and the second OSC signal is less than a preset range, and the preset range may be a minimum value that tends to zero, for example, may also be the first The difference between the wavelength values used by the OSC signal and the second OSC signal is zero, and thus the calculated one-way transmission delay error is extremely small.
  • the first OSC signal and the second OSC signal may adopt a frame structure of an OTN frame.
  • FIG. 10 is a schematic diagram of an OTN frame format according to an embodiment of the present invention.
  • the OTN frame is a standard modular structure of 4080 columns x 4 rows, 16 columns of the OTN frame header are overhead bytes, 3808 columns in the middle are payloads, and 256 columns in the tail are forward error correction (forward Error correction, FEC) Check byte.
  • FEC forward Error correction
  • the OTN frame includes: a frame alignment signal (FAS) byte located in rows 1-7 of the first row, which is used for providing frame synchronization positioning, and the seventh byte of the FAS is a multiframe indication (multi -frame alignment signal (MFAS), which is used to indicate the cost allocation when carrying multiple customer service data in time division multiplexing mode; the optical channel transmission unit k in the first row, columns 8-14 (optical channel transport unit-k Overhead, OTUk OH) byte, used to provide network management functions at the optical channel transmission unit level; optical channel data unit-k overhead (ODUk OH) in columns 1-4, columns 1-14 Bytes for providing maintenance and operation functions; OPUk OH (optical channel payload unit-k overhead) bytes in columns 15-16 for providing customer service data adaptation Features.
  • FAS frame alignment signal
  • MFAS multi -frame alignment signal
  • the OPUk OH byte includes a payload structure identifier (PSI), and the PSI has 0 to 255 possible values respectively under the MFAS indication, wherein the 0th byte is a customer service data type indication (payload type, PT).
  • the rest are reserved (RES), reserved for future expansion; the optical channel payload unit-k (OPUk) bytes in columns 17-3824 are used to provide customer service data.
  • the bearer function, the customer service data to be transmitted is encapsulated into the OPUk; and the FEC bytes located in columns 3825-4080 are used to provide error detection and error correction.
  • the coefficient k represents the supported bit rate, and the different bit rates correspond to different kinds of OPUk, ODUk and OTUk.
  • OPUk and OPUk OH constitute an OPUk frame
  • OPUk frame, ODUk OH and FAS constitute an ODUk frame
  • ODUk frame, OTUk OH and FEC constitute an OTUk frame.
  • the first timestamp and the second timestamp in this embodiment are located in the optical channel payload unit kbytes of columns 17-3824.
  • a method for measuring a time delay wherein an optical path is switched by an optical path selector, so that two OSC signals including time stamps are transmitted in the same optical fiber whose wavelength value is smaller than a preset range, thereby According to the timestamp, the one-way transmission delay between the two stations can be accurately measured.
  • FIG. 11 is a schematic diagram of an interaction process of another delay measurement method according to an embodiment of the present invention, where the method differs from the foregoing embodiment in that:
  • the method further includes a step S203, where the second station sends an acknowledgement message to the first station, where the acknowledgement message is used to indicate that the second station receives The first OSC signal.
  • the first station receives the confirmation message.
  • the site B sends an acknowledgement message to the site A, confirming receipt of the first timestamp. Since the optical switch is still operating in state 1 at this time, the acknowledgment message is transmitted by fiber 2 to station A.
  • the station B may not send an acknowledgement message to the station A, but the station A switches the optical switch state to the state 2 after the set time of the first OSC signal is sent.
  • the second station controls the second optical path selector to operate in the second state. Specifically, the second station controls the second optical path selector to operate in the second state according to the change of the optical power in the first optical fiber.
  • the SFP connected to the optical switch in the site B has two fixed ports, one is a sending port, and one is a receiving port. For example, when the optical switch is operating in state 1, the OSC signal is normally received by the receiving port of the SFP via the optical switch.
  • the optical switch when the optical switch is switched to state 2, at this time, the port of the SFP to which the optical switch is connected is swapped, and the original receiving port of the SFP cannot detect the OSC signal, that is, the received optical power becomes zero, and the controller of the station B
  • the optical switch of control station B operates in state 2 according to the change in optical power in the fiber.
  • the method further includes a step S209, where the second station performs the second according to the one-way transmission delay and the time of the first station.
  • the time of the site is synchronized with the time of the first site.
  • the station B may also extract the system time of the station A in the optical signal, and subtract the one-way transmission delay from the system time of the station A, that is, obtain the system time of the station B. Thereby, time synchronization is achieved as the site B as the slave site and the site A as the master site.
  • a step may be further included: the first station transmits a third OSC signal to the second station, the third OSC signal including an updated time of the first station.
  • the one-way transmission delay is updated to update the time of the second station.
  • the first station periodically sends the updated time of the first station, and the second station can implement time synchronization with the first station according to the updated time of the first station and the one-way transmission delay.
  • a method for measuring a time delay wherein an optical path is switched by an optical path selector, so that two OSC signals including time stamps are transmitted in the same optical fiber whose wavelength value is smaller than a preset range, thereby According to the timestamp, the one-way transmission delay between the two stations can be accurately measured; the slave station can also implement time synchronization with the primary station according to the one-way transmission delay.
  • FIG. 12 is a schematic structural diagram of a station according to an embodiment of the present invention.
  • the site 1000 can include:
  • the optical path control unit 11 is configured to control the optical path selector to operate in the first state
  • the sending unit 12 is configured to select the first optical fiber to send a first optical monitoring channel (OSC) signal to the second station, where the first OSC signal includes a first timestamp, and the first timestamp indicates that the first station sends the a first transmission time of the first OSC signal;
  • OSC optical monitoring channel
  • the optical path control unit 11 is further configured to control the optical path selector to operate in a second state
  • the receiving unit 13 is configured to: at the second receiving moment, select the first optical fiber to receive a second OSC signal from the second station, where the second OSC signal includes a second timestamp, and the second timestamp indicates the second a first reception time at which the station receives the first OSC signal, and a second transmission time at which the second station transmits the second OSC signal; a wavelength value used by the first OSC signal and the second OSC signal The difference is less than the preset range;
  • the calculating unit 14 is configured to calculate a one-way transmission delay between the first station and the second station according to the first sending time, the first receiving time, the second sending time, and the second receiving time.
  • the difference between the wavelength values used by the first OSC signal and the second OSC signal is zero. In this implementation, the difference between the wavelength values used by the two OSC signals is zero, so that the measured one-way transmission delay is completely error-free.
  • the one-way transmission delay is a half of a difference between the first operation value and the second operation value, where the first operation value is the second reception time and the first transmission a difference between the times, the second operation value being a difference between the second transmission time and the first reception time.
  • the one-way transmission delay is calculated based on the time at which the two stations recorded in the timestamp respectively transmit and receive the OSC signal.
  • the sending unit 12 is further configured to send the one-way transmission delay to the second station.
  • the first station calculates the one-way transmission delay
  • the first station sends a one-way transmission delay to the second station, so that the second station can accurately accurately according to the one-way transmission delay and the time of the first station. Time synchronization.
  • the receiving unit 13 is further configured to receive an acknowledgment message from the second station, where the acknowledgment message is used to indicate that the second station receives the first OSC signal.
  • the second station after receiving the first OSC signal, the second station sends an acknowledgement message to the first station to confirm that the first OSC signal is received, so that the first station can accurately switch the optical path.
  • the first station may also perform switching of the optical path after a preset time of transmitting the first OSC signal.
  • the optical path selector is a 2x2 optical switch. In this implementation, switching of the two optical paths can be easily achieved by a 2x2 optical switch.
  • the sending unit 12 is further configured to send a third OSC signal to the second station, where the third OSC signal includes an updated time of the first station.
  • the first station periodically sends the updated time of the first station, and the second station can implement time synchronization with the first station according to the updated time of the first station and the one-way transmission delay.
  • the optical path is switched by the optical path selector, so that the two OSC signals including the time stamp are transmitted in the same optical fiber whose wavelength value is smaller than the preset range, so that according to the time The stamp accurately measures the one-way transmission delay between the two stations.
  • FIG. 13 is a schematic structural diagram of another station according to an embodiment of the present invention.
  • the site 2000 can include:
  • the optical path control unit 21 is configured to control the optical path selector to operate in the first state
  • the receiving unit 22 is configured to select the first optical fiber to receive the first optical monitoring channel OSC signal from the first station, where the first OSC signal includes a first timestamp, and the first timestamp indicates that the first station sends a first transmission time of the first OSC signal;
  • the optical path control unit 21 is further configured to control the optical path selector to operate in a second state
  • the sending unit 23 is configured to select the first optical fiber to send a second OSC signal to the first station, where the second OSC signal includes a second timestamp, and the second timestamp indicates that the second station receives the The first OSC signal a receiving time, and a second sending time at which the second station sends the second OSC signal; a difference between wavelength values used by the first OSC signal and the second OSC signal is less than a preset range.
  • the difference between the wavelength values used by the first OSC signal and the second OSC signal is zero. In this implementation, the difference between the wavelength values used by the two OSC signals is zero, so that the measured one-way transmission delay is completely error-free.
  • the sending unit 23 is further configured to send an acknowledgement message to the first station, where the acknowledgement message is used to indicate that the second station receives the first OSC signal.
  • the second station after receiving the first OSC signal, the second station sends an acknowledgement message to the first station to confirm that the first OSC signal is received, so that the first station can accurately switch the optical path.
  • the first station may also perform switching of the optical path after a preset time of transmitting the first OSC signal.
  • the optical path control unit 21 is specifically configured to control the optical path selector to operate in the second state according to a change in optical power in the first optical fiber.
  • the first station does not need to notify the change of the optical path of the second station, and when the first station switches the state of the optical path selector, the second station can switch the optical path selector of the second station according to the change of the optical power in the optical fiber. status. Specifically, there is no light in the fiber, and the optical power is zero.
  • the receiving unit 22 is further configured to receive a one-way transmission delay sent by the first station. In this implementation manner, after the first station calculates the one-way transmission delay, the first station sends a one-way transmission delay to the second station, and the second station can perform time synchronization according to the one-way transmission delay and the time of the first station.
  • the station 2000 may further include: a time synchronization unit 24 (connected by a broken line in the figure), configured to use the second according to the one-way transmission delay and the time of the first station.
  • the time of the site is synchronized with the time of the first site.
  • the second station can accurately perform time synchronization according to the one-way transmission delay and the time of the first station.
  • the receiving unit 22 is further configured to receive a third OSC signal sent by the first station, where the third OSC signal includes an updated time of the first station; And updating the time of the second station according to the updated time of the first station and the one-way transmission delay.
  • the first station periodically sends the updated time of the first station, and the second station can accurately implement the time synchronization with the first station according to the updated time of the first station and the one-way transmission delay.
  • the one-way transmission delay is a half of a difference between the first operation value and the second operation value, wherein the first operation value is a second reception time and a first transmission time A difference between the second operation value is a difference between the second transmission time and the first reception time.
  • the one-way transmission delay is calculated based on the time at which the two stations recorded in the timestamp respectively transmit and receive the OSC signal.
  • the optical path selector is a 2x2 optical switch. In this implementation, switching of the two optical paths can be easily achieved by a 2x2 optical switch.
  • the optical path is switched by the optical path selector, so that the two OSC signals including the time stamp are transmitted in the same optical fiber whose wavelength value is smaller than the preset range, so that according to the time The stamp accurately measures the one-way transmission delay between the two stations.
  • the embodiment of the present invention further provides another station whose hardware structure is as shown in the OSC signal sending structure in the station A in FIG. 3 or FIG. 6, the station may include a controller, an optical path selector connected to the controller, and An optical interface unit connected to the optical path selector; in FIG. 3 and FIG. 6, the controller is an FPGA chip, and the optical path selector is a 2 ⁇ 2 light Switch, the optical interface unit is FIU. among them:
  • the controller is configured to control the optical path selector to operate in a first state, so that the optical interface unit selects the first optical fiber to send a first optical monitoring channel OSC signal to the second station, where the first OSC signal includes a first timestamp, where the first timestamp indicates that the first station sends the first sending moment of the first OSC signal;
  • the controller is further configured to control the optical path selector to operate in a second state, so that the optical interface unit selects the first optical fiber to receive a second OSC signal from the second station at a second receiving moment,
  • the second OSC signal includes a second timestamp, the second timestamp indicating that the second station receives the first receiving moment of the first OSC signal, and the second station sends the second OSC signal a second transmission time; a difference between wavelength values used by the first OSC signal and the second OSC signal is less than a preset range;
  • the controller is further configured to calculate a one-way transmission delay between the first station and the second station according to the first sending moment, the first receiving moment, the second sending moment, and the second receiving moment .
  • the difference between the wavelength values used by the first OSC signal and the second OSC signal is zero. In this implementation, the difference between the wavelength values used by the two OSC signals is zero, so that the measured one-way transmission delay is completely error-free.
  • the one-way transmission delay is a half of a difference between the first operation value and the second operation value, where the first operation value is the second reception time and the first transmission a difference between the times, the second operation value being a difference between the second transmission time and the first reception time.
  • the one-way transmission delay is calculated based on the time at which the two stations recorded in the timestamp respectively transmit and receive the OSC signal.
  • the optical interface unit is further configured to send the one-way transmission delay to the second station.
  • the first station calculates the one-way transmission delay
  • the first station sends a one-way transmission delay to the second station, so that the second station can accurately accurately according to the one-way transmission delay and the time of the first station. Time synchronization.
  • the optical interface unit is further configured to receive an acknowledgment message from the second station, where the acknowledgment message is used to indicate that the second station receives the first OSC signal.
  • the second station after receiving the first OSC signal, the second station sends an acknowledgement message to the first station to confirm that the first OSC signal is received, so that the first station can accurately switch the optical path.
  • the first station may also perform switching of the optical path after a preset time of transmitting the first OSC signal.
  • the optical path selector is a 2x2 optical switch. In this implementation, switching of the two optical paths can be easily achieved by a 2x2 optical switch.
  • the optical interface unit is further configured to send a third OSC signal to the second station, where the third OSC signal includes an updated time of the first station.
  • the first station periodically sends the updated time of the first station, and the second station can implement time synchronization with the first station according to the updated time of the first station and the one-way transmission delay.
  • the optical path is switched by the optical path selector, so that the two OSC signals including the time stamp are transmitted in the same optical fiber whose wavelength value is smaller than the preset range, so that according to the time The stamp accurately measures the one-way transmission delay between the two stations.
  • the embodiment of the present invention further provides another station whose hardware structure is as shown in the OSC signaling structure in the site B in FIG. 3 or FIG. 6, the site may include a controller, an optical path selector connected to the controller, and An optical interface unit connected to the optical path selector; in FIG. 3 and FIG. 6, the controller is an FPGA chip, and the optical path selector is a 2 ⁇ 2 light Switch, the optical interface unit is FIU. among them:
  • the controller is configured to control the optical path selector to operate in a first state, so that the optical interface unit selects the first optical fiber to receive a first optical monitoring channel OSC signal from the first station, where the first OSC signal includes a first timestamp, where the first timestamp indicates that the first station sends the first sending moment of the first OSC signal;
  • the controller is further configured to control the optical path selector to operate in a second state, so that the optical interface unit selects the first optical fiber to send a second OSC signal to the first station, where the second OSC signal includes a second timestamp, where the second timestamp indicates that the second station receives the first receiving moment of the first OSC signal, and the second station sends the second sending moment of the second OSC signal;
  • the difference between the wavelength values used by the first OSC signal and the second OSC signal is less than a preset range.
  • the difference between the wavelength values used by the first OSC signal and the second OSC signal is zero. In this implementation, the difference between the wavelength values used by the two OSC signals is zero, so that the measured one-way transmission delay is completely error-free.
  • the optical interface unit is further configured to send an acknowledgement message to the first station, where the acknowledgement message is used to indicate that the second site receives the first OSC signal.
  • the second station after receiving the first OSC signal, the second station sends an acknowledgement message to the first station to confirm that the first OSC signal is received, so that the first station can accurately switch the optical path.
  • the first station may also perform switching of the optical path after a preset time of transmitting the first OSC signal.
  • the optical path selector is specifically configured to control the optical path selector to operate in the second state according to a change in optical power in the first optical fiber.
  • the first station does not need to notify the change of the optical path of the second station, and when the first station switches the state of the optical path selector, the second station can switch the optical path selector of the second station according to the change of the optical power in the optical fiber. status. Specifically, there is no light in the fiber, and the optical power is zero.
  • the optical interface unit is further configured to receive a one-way transmission delay sent by the first station.
  • the first station sends a one-way transmission delay to the second station, and the second station can perform time synchronization according to the one-way transmission delay and the time of the first station.
  • the controller is further configured to synchronize the time of the second station with the time of the first station according to the one-way transmission delay and the time of the first station. .
  • the second station can accurately perform time synchronization according to the one-way transmission delay and the time of the first station.
  • the optical interface unit is further configured to receive a third OSC signal sent by the first station, where the third OSC signal includes an updated time of the first station; The time of the updated first station and the one-way transmission delay are updated for the time of the second station.
  • the first station periodically sends the updated time of the first station, and the second station can accurately implement the time synchronization with the first station according to the updated time of the first station and the one-way transmission delay.
  • the one-way transmission delay is a half of a difference between the first operation value and the second operation value, wherein the first operation value is a second reception time and a first transmission time A difference between the second operation value is a difference between the second transmission time and the first reception time.
  • the one-way transmission delay is calculated based on the time at which the two stations recorded in the timestamp respectively transmit and receive the OSC signal.
  • the optical path selector is a 2x2 optical switch. In this implementation, switching of the two optical paths can be easily achieved by a 2x2 optical switch.
  • the optical path is switched by the optical path selector, so that the two OSC signals including the time stamp are transmitted in the same optical fiber whose wavelength value is smaller than the preset range, so that according to the time The stamp accurately measures the one-way transmission delay between the two stations.
  • the disclosed systems, devices, and methods may be implemented in other manners.
  • the device embodiments described above are merely illustrative.
  • the division of the unit is only a logical function division.
  • there may be another division manner for example, multiple units or components may be combined or Can be integrated into another system, or some features can be ignored or not executed.
  • the mutual coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection through some interface, device or unit, and may be in an electrical, mechanical or other form.
  • the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of the embodiment.
  • each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.
  • the above embodiments it may be implemented in whole or in part by software, hardware, firmware, or any combination thereof.
  • software it may be implemented in whole or in part in the form of a computer program product.
  • the computer program product includes one or more computer instructions.
  • the computer program instructions When the computer program instructions are loaded and executed on a computer, the processes or functions described in accordance with embodiments of the present invention are generated in whole or in part.
  • the computer can be a general purpose computer, a special purpose computer, a computer network, or other programmable device.
  • the computer instructions can be stored in or transmitted by a computer readable storage medium.
  • the computer instructions may be from a website site, computer, server or data center via a wired (eg, coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (eg, infrared, wireless, microwave, etc.) Another website site, computer, server, or data center for transmission.
  • the computer readable storage medium can be any available media that can be accessed by a computer or a data storage device such as a server, data center, or the like that includes one or more available media.
  • the usable medium may be a magnetic medium (eg, a floppy disk, a hard disk, a magnetic tape), an optical medium (eg, a DVD), or a semiconductor medium (such as a solid state disk (SSD)) or the like.
  • the foregoing storage medium includes: a read-only memory (ROM) or a random access memory (RAM), a magnetic disk, or an optical disk, and the like, which can store program code.

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Abstract

本申请公开了一种时延测量方法及站点。其中的方法包括：第一站点控制光路选择器工作在第一状态，选择第一光纤向第二站点发送第一OSC信号，第一OSC信号包括第一时间戳；然后控制光路选择器工作在第二状态，在第二接收时刻选择第一光纤从第二站点接收第二OSC信号，第二OSC信号包括第二时间戳；再根据第一发送时刻、第一接收时刻、第二发送时刻和第二接收时刻计算第一站点和第二站点之间的单向传输时延。还公开了相应的站点。通过光路选择器进行光路的切换，使得包括时间戳的两路OSC信号在波长值之差小于预设的范围的同一根光纤中传输，从而根据该时间戳可准确地测量两个站点之间的单向传输时延。

Description

时延测量方法及站点 技术领域
本申请涉及光通信技术领域，尤其涉及一种时延测量方法及站点。
背景技术
在密集型光波复用(dense wavelength division multiplexing，DWDM)***中，分为C波段光信号(c-band optical signal，C-BAND)传输信道和光监控信道(optical supervisory channel，OSC)。C-BAND传输信道和OSC信道的波长不同。C-BAND传输信道用于传输业务，OSC信道用于传输监控管理信息。
为实现光传送网(optical transport network，OTN)中任意两个站点之间的时间同步，在OSC信道中有专门的时隙用于传输两个站点之间的时戳信息，实现光纤连接的两个站点之间的时间同步。
现有技术采用“单纤双向”的方式测量站点之间的单向传输时延，从而进行时间同步。如图1所示的现有技术的光传输网络组网结构示意图，OSC信号在同一根光纤1中来回传输，可以计算得到光信号的传输时延。具体是如图2所示的时戳传输示意图，通过OSC信道中传输的两个站点之间的时戳信息，根据时戳信息计算得到单向传输时延。
采用“单纤双向”方式时，必须使用两种不同波长在光纤中往返。因为如果A、B站点的发送波长相同，那么A站点发送的信号在经过合波器时存在反射，与B站点发送过来的信号混合，使得A站点无法正确接收B站点发送过来的信号。例如，如图1所示，A站点发送波长为1491nm，B站点发送波长为1511nm。然而，在长纤中传输的时候，由于光纤色散，导致两种波长传输的时延不相等(当长纤类型为G.652，长度为80km时，传输延时差为27ns)，通过往返时延之和取一半，将产生13ns的误差，并且无法进行补偿。
因此，采用现有技术的方案无法准确测量出站点之间的单向传输时延。
发明内容
本申请提供了一种时延测量方法及站点，以实现准确地测量站点之间的单向传输时延。
本申请的一方面，提供了一种时延测量方法，包括：第一站点控制光路选择器工作在第一状态，以使所述第一站点选择第一光纤向第二站点发送第一光监控信道OSC信号，所述第一OSC信号包括第一时间戳，所述第一时间戳指示所述第一站点发送所述第一OSC信号的第一发送时刻；所述第一站点控制所述光路选择器工作在第二状态，以使所述第一站点在第二接收时刻选择所述第一光纤从第二站点接收第二OSC信号，所述第二OSC信号包括第二时间戳，所述第二时间戳指示所述第二站点接收所述第一OSC信号的第一接收时刻，以及所述第二站点发送所述第二OSC信号的第二发送时刻；所述第一OSC信号和所述第二OSC信号使用的波长值之差小于预设的范围；所述第一站点根据所述第一发送时刻、第一接收时刻、第二发送时刻和第二接收时刻计算所述第一站点和所述第二站点之间的单向传输时延。在该实现方式中，通过光路选择器进行光路的切换，使得包括时间戳的 两路OSC信号在波长值之差小于预设的范围的同一根光纤中传输，从而根据该时间戳可准确地测量两个站点之间的单向传输时延。
在一个实现方式中，所述第一站点选择第一光纤向第二站点发送第一OSC信号之后，所述方法还包括：所述第一站点接收来自所述第二站点的确认消息，所述确认消息用于指示所述第二站点接收到所述第一OSC信号。在该实现方式中，第二站点在接收到第一OSC信号后，向第一站点发送确认消息，确认接收到该第一OSC信号，从而第一站点可以准确地进行光路的切换。当然，在另外的实现方式中，第一站点也可以在发送第一OSC信号的预设时间后进行光路的切换。
在另一个实现方式中，所述第一站点根据所述第一发送时刻、第一接收时刻、第二发送时刻和第二接收时刻计算所述第一站点和所述第二站点之间的单向传输时延之后，所述方法还包括：所述第一站点向所述第二站点发送所述单向传输时延。在该实现方式中，第一站点计算出单向传输时延后，向第二站点发送单向传输时延，以使第二站点能根据该单向传输时延和第一站点的时间准确地进行时间同步。
在又一个实现方式中，所述第一站点向所述第二站点发送所述单向传输时延之后，所述方法还包括：所述第一站点向所述第二站点发送第三OSC信号，所述第三OSC信号包括更新的所述第一站点的时间。在该实现方式中，第一站点定期发送更新的第一站点的时间，第二站点根据更新的第一站点的时间和单向传输时延，可以实现与第一站点的时间同步。
本申请的另一方面，提供了一种时延测量方法，包括：所述第二站点控制光路选择器工作在第一状态，以使所述第二站点选择第一光纤从所述第一站点接收第一光监控信道OSC信号，所述第一OSC信号包括第一时间戳，所述第一时间戳指示所述第一站点发送所述第一OSC信号的第一发送时刻；所述第二站点控制所述光路选择器工作在第二状态，以使所述第二站点选择所述第一光纤向所述第一站点发送第二OSC信号，所述第二OSC信号包括第二时间戳，所述第二时间戳指示所述第二站点接收所述第一OSC信号的第一接收时刻，以及所述第二站点发送所述第二OSC信号的第二发送时刻；所述第一OSC信号和所述第二OSC信号使用的波长值之差小于预设的范围。在该实现方式中，通过光路选择器进行光路的切换，使得包括时间戳的两路OSC信号在波长值之差小于预设的范围的同一根光纤中传输，从而根据该时间戳可准确地测量两个站点之间的单向传输时延。
在一个实现方式中，所述第二站点选择第一光纤从所述第一站点接收第一OSC信号之后，所述方法还包括：所述第二站点向所述第一站点发送确认消息，所述确认消息用于指示所述第二站点接收到所述第一OSC信号。在该实现方式中，第二站点在接收到第一OSC信号后，向第一站点发送确认消息，确认接收到该第一OSC信号，从而第一站点可以准确地进行光路的切换。当然，在另外的实现方式中，第一站点也可以在发送第一OSC信号的预设时间后进行光路的切换。
在另一个实现方式中，所述第二站点控制所述光路选择器工作在第二状态，包括：所述第二站点根据所述第一光纤中光功率的变化，控制所述光路选择器工作在所述第二状态。在该实现方式中，无需第一站点通知第二站点光路的变化，第一站点在切换光路选择器的状态时，第二站点可以根据光纤中光功率的变化，切换第二站点的光路选择器的状态。具 体地，该光纤中无光，光功率为零。
在又一个实现方式中，所述第二站点选择所述第一光纤向所述第一站点发送第二OSC信号之后，所述方法还包括：所述第二站点接收所述第一站点发送的单向传输时延。在该实现方式中，第一站点计算出单向传输时延后，向第二站点发送单向传输时延，第二站点能根据该单向传输时延和第一站点的时间进行时间同步。
在又一个实现方式中，所述第二站点接收所述第一站点发送的单向传输时延之后，所述方法还包括：所述第二站点根据所述单向传输时延和所述第一站点的时间，将所述第二站点的时间与所述第一站点的时间进行同步。在该实现方式中，第二站点能根据该单向传输时延和第一站点的时间准确地进行时间同步。
在又一种实现方式中，所述第二站点根据所述第一站点的时间，进行时间校准之后，所述方法还包括：所述第二站点接收所述第一站点发送的第三OSC信号，所述第三OSC信号包括更新的第一站点的时间；所述第二站点根据所述更新的第一站点的时间和所述单向传输时延，对所述第二站点的时间进行更新。在该实现方式中，第一站点定期发送更新的第一站点的时间，第二站点根据更新的第一站点的时间和单向传输时延，可以准确地实现与第一站点的时间同步。
结合上述的本申请的任一方面，在一个实现方式中，所述第一OSC信号和所述第二OSC信号使用的波长值之差为零。在该实现方式中，两个OSC信号使用的波长值之差为零，可以使得测量出的单向传输时延完全无误差。
结合上述的本申请的任一方面，在另一个实现方式中，所述单向传输时延为第一运算值与第二运算值之间的差值的一半，其中，所述第一运算值为第二接收时刻与第一发送时刻之间的差值，所述第二运算值为第二发送时刻与所述第一接收时刻之间的差值。在该实现方式中，单向传输时延是根据时间戳中记录的两个站点分别发送和接收OSC信号的时刻来计算得到的。
结合上述的本申请的任一方面，在又一个实现方式中，所述光路选择器为2×2光开关。在该实现方式中，通过2×2光开关可以简单地实现两种光路的切换。
本申请的又一方面，提供了一种站点，该站点具有实现上述方法中站点行为的功能。所述功能可以通过硬件实现，也可以通过硬件执行相应的软件实现。所述硬件或软件包括一个或多个与上述功能相对应的模块。
一种可能的实现方式中，所述站点包括：光路控制单元，用于控制光路选择器工作在第一状态；发送单元，用于选择第一光纤向第二站点发送第一光监控信道OSC信号，所述第一OSC信号包括第一时间戳，所述第一时间戳指示所述第一站点发送所述第一OSC信号的第一发送时刻；所述光路控制单元，还用于控制所述光路选择器工作在第二状态；接收单元，用于在第二接收时刻选择所述第一光纤从第二站点接收第二OSC信号，所述第二OSC信号包括第二时间戳，所述第二时间戳指示所述第二站点接收所述第一OSC信号的第一接收时刻，以及所述第二站点发送所述第二OSC信号的第二发送时刻；所述第一OSC信号和所述第二OSC信号使用的波长值之差小于预设的范围；计算单元，用于根据所述第一发送时刻、第一接收时刻、第二发送时刻和第二接收时刻计算所述第一站点和所述第二 站点之间的单向传输时延。
另一种可能的实现方式中，所述站点包括：控制器、与所述控制器连接的光路选择器、以及与所述光路选择器连接的光接口单元；其中：所述控制器，用于控制所述光路选择器工作在第一状态，以使所述光接口单元选择第一光纤向第二站点发送第一光监控信道OSC信号，所述第一OSC信号包括第一时间戳，所述第一时间戳指示第一站点发送所述第一OSC信号的第一发送时刻；所述控制器，还用于控制所述光路选择器工作在第二状态，以使所述光接口单元在第二接收时刻选择所述第一光纤从所述第二站点接收第二OSC信号，所述第二OSC信号包括第二时间戳，所述第二时间戳指示所述第二站点接收所述第一OSC信号的第一接收时刻，以及所述第二站点发送所述第二OSC信号的第二发送时刻；所述第一OSC信号和所述第二OSC信号使用的波长值之差小于预设的范围；所述控制器，还用于根据所述第一发送时刻、第一接收时刻、第二发送时刻和第二接收时刻计算所述第一站点和所述第二站点之间的单向传输时延。
基于同一发明构思，由于该装置解决问题的原理以及有益效果可以参见上述各可能的站点的方法实施方式以及所带来的有益效果，因此该装置的实施可以参见方法的实施，重复之处不再赘述。
本申请的又一方面，提供了一种站点，该站点具有实现上述方法中站点行为的功能。所述功能可以通过硬件实现，也可以通过硬件执行相应的软件实现。所述硬件或软件包括一个或多个与上述功能相对应的模块。
一种可能的实现方式中，所述站点包括：光路控制单元，用于控制光路选择器工作在第一状态；接收单元，用于选择第一光纤从所述第一站点接收第一光监控信道OSC信号，所述第一OSC信号包括第一时间戳，所述第一时间戳指示所述第一站点发送所述第一OSC信号的第一发送时刻；所述光路控制单元，还用于控制所述光路选择器工作在第二状态；发送单元，用于选择所述第一光纤向所述第一站点发送第二OSC信号，所述第二OSC信号包括第二时间戳，所述第二时间戳指示所述第二站点接收所述第一OSC信号的第一接收时刻，以及所述第二站点发送所述第二OSC信号的第二发送时刻；所述第一OSC信号和所述第二OSC信号使用的波长值之差小于预设的范围。
另一种可能的实现方式中，所述站点包括：控制器、与所述控制器连接的光路选择器、以及与所述光路选择器连接的光接口单元；其中：所述控制器，用于控制所述光路选择器工作在第一状态，以使所述光接口单元选择第一光纤从第一站点接收第一光监控信道OSC信号，所述第一OSC信号包括第一时间戳，所述第一时间戳指示所述第一站点发送所述第一OSC信号的第一发送时刻；所述控制器，还用于控制所述光路选择器工作在第二状态，以使所述光接口单元选择所述第一光纤向第一站点发送第二OSC信号，所述第二OSC信号包括第二时间戳，所述第二时间戳指示所述第二站点接收所述第一OSC信号的第一接收时刻，以及所述第二站点发送所述第二OSC信号的第二发送时刻；所述第一OSC信号和所述第二OSC信号使用的波长值之差小于预设的范围。
基于同一发明构思，由于该装置解决问题的原理以及有益效果可以参见上述各可能的站点的方法实施方式以及所带来的有益效果，因此该装置的实施可以参见方法的实施，重 复之处不再赘述。
本申请的又一方面提供了一种计算机可读存储介质，所述计算机可读存储介质中存储有指令，当其在计算机上运行时，使得计算机执行上述各方面所述的方法。
本申请的又一方面提供了一种通信芯片，其中存储有指令，当其在网络设备或终端设备上运行时，使得计算机执行上述各方面所述的方法。
本申请的又一方面提供了一种包含指令的计算机程序产品，当其在计算机上运行时，使得计算机执行上述各方面所述的方法。
附图说明
为了更清楚地说明本发明实施例或背景技术中的技术方案，下面将对本发明实施例或背景技术中所需要使用的附图进行说明。
图1为现有技术的光传输网络组网结构示意图；
图2为现有技术的时戳传输示意图；
图3为本发明实施例提供的一种光传输网络的组网结构示意图；
图4为本发明实施例提供的一种光传送网设备的结构示意图；
图5为本发明实施例的光开关的工作状态示意图；
图6为本发明实施例提供的另一种光传输网络的组网结构示意图；
图7为本发明实施例提供的一种时延测量方法的交互流程图；
图8为本发明实施例的时戳传输示意图；
图9为本发明实施例提供的又一种光传输网络组网结构示意图；
图10为本发明实施例提供的一种OTN帧格式示意图；
图11为本发明实施例提供的另一种时延测量方法的交互流程示意图；
图12为本发明实施例提供的一种站点的结构示意图；
图13为本发明实施例提供的另一种站点的结构示意图。
具体实施方式
下面将结合本发明实施例中的附图对本发明实施例进行描述。
请参阅图3，图3为本发明实施例提供的一种光传输网络的组网结构示意图，示意了第一站点(图中为站点A)和第二站点(图中为站点B)之间的光通信结构，站点A和站点B可以是OTN设备。OTN设备的通用结构如图4所示。在图4中，OTN设备100包括支路板1、交叉板2和线路板3。业务的传输方向可以从客户侧到线路侧，还可以从线路侧到客户侧。客户侧发送或接收的业务称为客户侧业务，线路侧接收或发送的业务称为波分侧业务。两个方向上的业务处理流程互为逆向过程，本实施例中以客户侧到线路侧方向为例进行说明：
支路板1，完成客户业务的封装映射。客户业务包括多种业务类型，例如包业务、恒定比特率(constant bit rate，CBR)业务。其中，包业务可以包括以太网媒体接入控制(media access control，MAC)包业务、灵活以太网(FlexE)包业务、多协议标签交换(multiprotocol label switching，MPLS)包业务、因特网协议(internetwork protocol，IP)报文等。cbr业 务可以包括同步数字体系(synchronous digital hierarchy，SDH)业务、OTN业务、通用公共无线电接口(common public radio interface，CPRI)业务、或者其他时分复用(time division multiplexing，TDM)类型业务。具体地，支路板1用于接收来自客户侧的客户业务，将接收到的客户业务封装映射到光数据单元(optical data unit，ODU)信号并添加相应的OTN管理监控开销。在支路板1上，ODU信号可以是ODUflex、ODU0、ODU1、ODU2、ODU2e、ODU3、ODU4等，OTN管理监控开销可以为ODU开销。针对不同类型的客户业务，可以采用不同的方式封装映射到不同的ODU信号中。
交叉板2，完成支路板和线路板的全交叉连接，实现ODU信号的灵活交叉调度。具体地，交叉板可以实现将ODU信号从任意一个支路板传输到任意一个线路板，或者将OTU信号从任意一个线路板传输到任意一个线路板，还可以将客户信号从任意一个支路板传输到任意一个支路板。
线路板3，将ODU信号形成光传输单元(optical transport unit，OTU)信号并发送到线路侧。在ODU信号形成OTU信号之前，线路板3可以将多路相对速率较低的ODU信号复用到相对速率较高的ODU信号中。在ODU信号添加相应OTN管理监控开销，形成OTU信号并发送到线路侧的光传输通道中。在线路板3上，ODU信号可以为ODU1、ODU2、ODU3、ODU4、ODUCn等，OTU信号(可以是经过复用或者没有复用的)可以为OTU1、OTU2、OTU3、OTU4、ODUCn等。OTN管理监控开销可以为OTU开销。
线路侧业务信号经过OM或OD，然后再经光放大器(optical amplifier，OA)放大，经光接口单元(fiber interface unit，FIU)发送出去。
以上描述的是业务信号的传输。在光传送网中，还有一类信号，即OSC信号。在图3所示的结构图中，由OSC单元产生的OSC信号经FIU发送出去。每个站点中进行OSC信号传送的器件，即SC1，可包括控制器、与控制器依次连接的小型可插拔光模块(small form-factor pluggables，SFP)、光路选择器和光接口单元。具体地，控制器是电芯片，负责时戳信号的***、提取，且最终送出/接收OSC信道的155M电信号，是站点中其它元件的总控制芯片。在图3中，该控制器是FPGA芯片。SFP是光电转换模块，它接收控制器的电信号，在内部进行电-光转换，送出电信号；同时，它接收光信号，在内部进行光-电转换，送出电信号。SFP还可以带光时域反射仪(optical time domain reflectometer，OTDR)。本实施例中站点A中的SFP通过一个第一光路选择器连接到FIU，站点B中的SFP通过一个第二光路选择器连接到FIU。第一/第二光路选择器用于根据控制指令进行光路的选择。
本实施例采用“单纤单向”的光通信方式，如图3所示，光信号通过光纤1从站点A发送到站点B，站点B反馈回来的光信号则从光纤2发送到站点A。这样就不会存在现有技术中的站点A发送的信号在经过合波器时，与站点B发送过来的信号混合的情况。
在图3中，站点A中的第一光路选择器和站点B中的第二光路选择器为一个2×2的光开关，通过2×2光开关可以简单地实现两种光路的切换。2×2光开关为四端口光器件，2×2光开关可工作在两种状态，由控制器进行状态的切换控制。如图5所示的本发明实施例的光开关的工作状态示意图，在图5的左图中，为光开关的状态1，端口A与端口C连接，端口B与端口D连接；在图5的右图中，为光开关的状态2，端口A与端口D连接，端口B与端口C连接。另外，合/分波器用于将OSC信号与C-BAND信号合并/分开。合/ 分波器可以是FIU，也可以是SFIU。另外，若站点A作为主站点、站点B作为从站点，站点B还可以包括与控制器连接的时钟同步电路，用于实现与站点A的时钟同步。
具体进行时延测量时，是针对每根光纤单独进行测量，例如测量图3中的光纤1或光纤2的单向传输时延。因此，如果测量光纤1的单向传输时延，则如图6所示的本发明实施例提供的另一种光传输网络的组网结构示意图，光开关也可以不连接光纤2，为半双工通信；如果测量光纤2的单向传输时延，则光开关也可以不连接光纤1。
图7为本发明实施例提供的一种时延测量方法的交互流程图，应用于两个站点之间的时延测量。该方法可包括以下步骤：
S101、第一站点控制第一光路选择器工作在第一状态。
S101’、第二站点控制第二光路选择器工作在第一状态。
S102、所述第一站点选择第一光纤向第二站点发送第一OSC信号，所述第一OSC信号包括第一时间戳，所述第一时间戳指示所述第一站点发送所述第一OSC信号的第一发送时刻。
S103、所述第一站点控制所述第一光路选择器工作在第二状态。
S104、所述第二站点控制所述第二光路选择器工作在第二状态。
S105、所述第二站点选择所述第一光纤向所述第一站点发送第二OSC信号，所述第二OSC信号包括第二时间戳，所述第二时间戳指示所述第二站点接收所述第一OSC信号的第一接收时刻，以及所述第二站点发送所述第二OSC信号的第二发送时刻；所述第一OSC信号和所述第二OSC信号使用的波长值之差小于预设的范围。
S106、所述第一站点根据所述第一发送时刻、第一接收时刻、第二发送时刻和第二接收时刻计算所述第一站点和所述第二站点之间的单向传输时延。
结合上面的流程，描述两个站点的具体工作方式如下：
首先，如步骤S101和S101’所示，站点上电后，每个站点的控制器控制光开关工作在状态1(如图5中的光开关实线所示)。站点A和站点B的控制器发送、接收OSC信号，建立OSC通信；同时，由于站点A与站点B之间是串行传输，站点B使用时钟同步电路提取OSC信号中的时钟，实现站点B与站点A的时钟同步。
然后，如步骤S102所示，站点A发送第一OSC信号给站点B，站点B接收该第一OSC信号。具体地，第一OSC信号经过光纤1由站点A发送到站点B。如图8所示的本发明实施例的时戳传输示意图，该第一OSC信号包括第一时间戳，该第一时间戳包括站点A发送第一OSC信号的第一发送时刻T1A。站点B接收到该第一OSC信号时，记录第一接收时刻T1B，并将T1B保存到第二时间戳中，然后将该第二时间戳驻留起来。
接着，如步骤S103所示，站点A切换光开关工作在状态2，然后，如步骤S104所示，站点B也切换光开关工作在状态2。
接着，如步骤S105和图8所示，站点B在驻留的第二时间戳中加入发送时刻T2B，并发送第二OSC信号给站点A，该第二OSC信号包括第二时间戳。具体地，如图9所示的本发明实施例提供的又一种光传输网络组网结构示意图，站点B的控制器将第二OSC信号由光开关(如图9中的站点B的光开关虚线所示)经过光纤1发送到站点A，站点A由光开关(如图9中的站点A的光开关虚线所示)将接收到的第二OSC信号传输至站点A 的控制器。该第二时间戳包括第一接收时刻T1B、第二发送时刻T2B。另外，第二时间戳也可以还包括第一发送时刻T1A。站点A在第二接收时刻T2A接收到第二OSC信号时，将第二接收时刻T2A保存到时间戳中。
最后，如步骤S106所示，站点A根据第一发送时刻T1A、第一接收时刻T1B、第二发送时刻T2B、第二接收时刻T2A计算站点A与站点B之间的单向传输时延D。具体地，所述单向传输时延为第一运算值与第二运算值之间的差值的一半，其中，所述第一运算值为第二接收时刻与第一发送时刻之间的差值，所述第二运算值为第二发送时刻与所述第一接收时刻之间的差值。在本示例中，单向传输时延D＝(T2A-T1A-(T2B-T1B))/2，其中，第一运算值(T2A-T1A)为时间戳在光纤1中来回传输的总时间，第二运算值(T2B-T1B)为时间戳在站点B中驻留的时间。在本实施例中，第一OSC信号和第二OSC信号使用的波长值之差小于预设的范围，该预设的范围可以是一个趋向于零的极小值，例如，也可以是第一OSC信号和第二OSC信号使用的波长值之差为零，因而，计算出的单向传输时延误差极小。
在本实施例中，第一OSC信号和第二OSC信号可以采用OTN帧的帧结构。如图10所示，为本发明实施例提供的一种OTN帧格式示意图。如图10所示，OTN帧为4080列×4行的标准模块化结构，OTN帧头部的16列为开销字节，中部的3808列为净荷，尾部256列为前向纠错(forward error correction，FEC)校验字节。该OTN帧包括：位于第1行第1-7列的帧对齐信号(frame alignment signal，FAS)字节，用于提供帧同步定位的功能，FAS的第7个字节为复帧指示(multi-frame alignment signal，MFAS)，用于指示以时分复用方式承载多个客户业务数据时的开销分配；位于第1行第8-14列的光通道传输单元k开销(optical channel transport unit-k overhead，OTUk OH)字节，用于提供光通道传送单元级别的网络管理功能；位于第2-4行第1-14列的光通道数据单元k开销(optical channel data unit-k overhead，ODUk OH)字节，用于提供维护和操作功能；位于第15-16列的OPUk OH(optical channel payload unit-k overhead，光通道净荷单元k开销)字节，用于提供客户业务数据适配的功能。OPUk OH字节中包括净荷结构标识(payload structure identifier，PSI)，PSI在MFAS指示下分别对应有0～255个可能值，其中第0字节为客户业务数据类型指示(payload type，PT)，其余为保留字节(reserved，RES)，留做未来扩展使用；位于第17-3824列的光通道净荷单元k(optical channel payload unit-k，OPUk)字节，用于提供客户业务数据承载的功能，待传输的客户业务数据被封装入OPUk中；以及位于第3825-4080列的FEC字节，用于提供错误探测和纠错功能。系数k表示所支持的比特速率，不同的比特速率对应于不同种类的OPUk、ODUk和OTUk。其中，k＝0表示比特速率为1.25Gbit/s，k＝1表示比特速率为2.5Gbit/s，k＝2表示比特速率为10Gbit/s，k＝3表示比特速率为40Gbit/s，k＝4表示比特速率为100Gbit/s。其中，OPUk和OPUk OH构成了OPUk帧，OPUk帧、ODUk OH和FAS构成ODUk帧，ODUk帧、OTUk OH和FEC构成了OTUk帧。
本实施例中的第一时间戳和第二时间戳位于第17-3824列的光通道净荷单元k字节。
根据本发明实施例提供的一种时延测量方法，通过光路选择器进行光路的切换，使得包括时间戳的两路OSC信号在波长值之差小于预设的范围的同一根光纤中传输，从而根据该时间戳可准确地测量两个站点之间的单向传输时延。
图11为本发明实施例提供的另一种时延测量方法的交互流程示意图，该方法与前述实施例的不同在于：
在第一站点向第二站点发送完第一OSC信号之后，还包括步骤S203，所述第二站点向所述第一站点发送确认消息，所述确认消息用于指示所述第二站点接收到所述第一OSC信号。所述第一站点接收所述确认消息。具体如图8所示，站点B向站点A发送确认消息，确认接收到第一时戳。由于此时光开关仍工作在状态1，该确认消息是由光纤2传输至站点A。
作为另一种实现方式，站点B也可以不向站点A发送确认消息，而是站点A在发送完第一OSC信号的设定时间后，切换光开关状态至状态2。
另外，第二站点控制第二光路选择器工作在第二状态，具体为：第二站点根据所述第一光纤中光功率的变化，控制所述第二光路选择器工作在第二状态。具体实现中，站点B中与光开关连接的SFP具有两个固定的端口，一个为发送端口，一个为接收端口。例如，当光开关工作在状态1时，OSC信号经过光开关正常地由SFP的接收端口接收。但当光开关切换至状态2时，此时，光开关连接的SFP的端口发生了对换，SFP原来的接收端口检测不到OSC信号，即接收光功率变为零，则站点B的控制器根据光纤中光功率的变化，控制站点B的光开关工作在状态2。
另外，在第一站点向第二站点发送单向传输时延之后，还包括步骤S209，所述第二站点根据所述单向传输时延和所述第一站点的时间，将所述第二站点的时间与所述第一站点的时间进行同步。具体实现中，站点B接收到单向传输时延后，还可以在光信号中提取站点A的***时间，将站点A的***时间减去单向传输时延，即得到站点B的***时间，从而实现作为从站点的站点B与作为主站点的站点A的时间同步。
此外，步骤S209之后，还可包括步骤(未示出)：所述第一站点向所述第二站点发送第三OSC信号，所述第三OSC信号包括更新的所述第一站点的时间。所述第二站点接收所述第一站点发送的第三OSC信号，所述第三OSC信号包括更新的第一站点的时间；所述第二站点根据所述更新的第一站点的时间和所述单向传输时延，对所述第二站点的时间进行更新。具体实现中，第一站点定期发送更新的第一站点的时间，第二站点根据更新的第一站点的时间和单向传输时延，可以实现与第一站点的时间同步。
根据本发明实施例提供的一种时延测量方法，通过光路选择器进行光路的切换，使得包括时间戳的两路OSC信号在波长值之差小于预设的范围的同一根光纤中传输，从而根据该时间戳可准确地测量两个站点之间的单向传输时延；从站点还可根据单向传输时延实现与主站点的时间同步。
上述详细阐述了本发明实施例的方法，下面提供了本发明实施例的装置。
请参阅图12，为本发明实施例提供的一种站点的结构示意图。该站点1000可包括：
光路控制单元11，用于控制光路选择器工作在第一状态；
发送单元12，用于选择第一光纤向第二站点发送第一光监控信道OSC信号，所述第一OSC信号包括第一时间戳，所述第一时间戳指示所述第一站点发送所述第一OSC信号的第一发送时刻；
所述光路控制单元11，还用于控制所述光路选择器工作在第二状态；
接收单元13，用于在第二接收时刻选择所述第一光纤从第二站点接收第二OSC信号，所述第二OSC信号包括第二时间戳，所述第二时间戳指示所述第二站点接收所述第一OSC信号的第一接收时刻，以及所述第二站点发送所述第二OSC信号的第二发送时刻；所述第一OSC信号和所述第二OSC信号使用的波长值之差小于预设的范围；
计算单元14，用于根据所述第一发送时刻、第一接收时刻、第二发送时刻和第二接收时刻计算所述第一站点和所述第二站点之间的单向传输时延。
在一种实现方式中，所述第一OSC信号和所述第二OSC信号使用的波长值之差为零。在该实现方式中，两个OSC信号使用的波长值之差为零，可以使得测量出的单向传输时延完全无误差。
在另一种实现方式中，所述单向传输时延为第一运算值与第二运算值之间的差值的一半，其中，所述第一运算值为第二接收时刻与第一发送时刻之间的差值，所述第二运算值为第二发送时刻与所述第一接收时刻之间的差值。在该实现方式中，单向传输时延是根据时间戳中记录的两个站点分别发送和接收OSC信号的时刻来计算得到的。
在又一种实现方式中，所述发送单元12，还用于向所述第二站点发送所述单向传输时延。在该实现方式中，第一站点计算出单向传输时延后，向第二站点发送单向传输时延，以使第二站点能根据该单向传输时延和第一站点的时间准确地进行时间同步。
在又一种实现方式中，所述接收单元13，还用于接收来自所述第二站点的确认消息，所述确认消息用于指示所述第二站点接收到所述第一OSC信号。在该实现方式中，第二站点在接收到第一OSC信号后，向第一站点发送确认消息，确认接收到该第一OSC信号，从而第一站点可以准确地进行光路的切换。当然，在另外的实现方式中，第一站点也可以在发送第一OSC信号的预设时间后进行光路的切换。
在又一种实现方式中，所述光路选择器为2×2光开关。在该实现方式中，通过2×2光开关可以简单地实现两种光路的切换。
在又一个实现方式中，所述发送单元12，还用于向所述第二站点发送第三OSC信号，所述第三OSC信号包括更新的所述第一站点的时间。在该实现方式中，第一站点定期发送更新的第一站点的时间，第二站点根据更新的第一站点的时间和单向传输时延，可以实现与第一站点的时间同步。
根据本发明实施例提供的一种站点，通过光路选择器进行光路的切换，使得包括时间戳的两路OSC信号在波长值之差小于预设的范围的同一根光纤中传输，从而根据该时间戳可准确地测量两个站点之间的单向传输时延。
请参阅图13，为本发明实施例提供的另一种站点的结构示意图。该站点2000可包括：
光路控制单元21，用于控制光路选择器工作在第一状态；
接收单元22，用于选择第一光纤从所述第一站点接收第一光监控信道OSC信号，所述第一OSC信号包括第一时间戳，所述第一时间戳指示所述第一站点发送所述第一OSC信号的第一发送时刻；
所述光路控制单元21，还用于控制所述光路选择器工作在第二状态；
发送单元23，用于选择所述第一光纤向所述第一站点发送第二OSC信号，所述第二OSC信号包括第二时间戳，所述第二时间戳指示所述第二站点接收所述第一OSC信号的第 一接收时刻，以及所述第二站点发送所述第二OSC信号的第二发送时刻；所述第一OSC信号和所述第二OSC信号使用的波长值之差小于预设的范围。
在一种实现方式中，所述第一OSC信号和所述第二OSC信号使用的波长值之差为零。在该实现方式中，两个OSC信号使用的波长值之差为零，可以使得测量出的单向传输时延完全无误差。
在另一种实现方式中，所述发送单元23，还用于向所述第一站点发送确认消息，所述确认消息用于指示所述第二站点接收到所述第一OSC信号。在该实现方式中，第二站点在接收到第一OSC信号后，向第一站点发送确认消息，确认接收到该第一OSC信号，从而第一站点可以准确地进行光路的切换。当然，在另外的实现方式中，第一站点也可以在发送第一OSC信号的预设时间后进行光路的切换。
在又一个实现方式中，所述光路控制单元21具体用于根据所述第一光纤中光功率的变化，控制所述光路选择器工作在所述第二状态。在该实现方式中，无需第一站点通知第二站点光路的变化，第一站点在切换光路选择器的状态时，第二站点可以根据光纤中光功率的变化，切换第二站点的光路选择器的状态。具体地，该光纤中无光，光功率为零。
在又一种实现方式中，所述接收单元22，还用于接收所述第一站点发送的单向传输时延。在该实现方式中，第一站点计算出单向传输时延后，向第二站点发送单向传输时延，第二站点能根据该单向传输时延和第一站点的时间进行时间同步。
在又一种实现方式中，站点2000还可包括：时间同步单元24(图中以虚线连接)，用于根据所述单向传输时延和所述第一站点的时间，将所述第二站点的时间与所述第一站点的时间进行同步。在该实现方式中，第二站点能根据该单向传输时延和第一站点的时间准确地进行时间同步。
在又一种实现方式中，所述接收单元22，还用于接收所述第一站点发送的第三OSC信号，所述第三OSC信号包括更新的第一站点的时间；所述第二站点根据所述更新的第一站点的时间和所述单向传输时延，对所述第二站点的时间进行更新。在该实现方式中，第一站点定期发送更新的第一站点的时间，第二站点根据更新的第一站点的时间和单向传输时延，可以准确地实现与第一站点的时间同步。
在又一个实现方式中，所述单向传输时延为第一运算值与第二运算值之间的差值的一半，其中，所述第一运算值为第二接收时刻与第一发送时刻之间的差值，所述第二运算值为第二发送时刻与所述第一接收时刻之间的差值。在该实现方式中，单向传输时延是根据时间戳中记录的两个站点分别发送和接收OSC信号的时刻来计算得到的。
在又一个实现方式中，所述光路选择器为2×2光开关。在该实现方式中，通过2×2光开关可以简单地实现两种光路的切换。
根据本发明实施例提供的一种站点，通过光路选择器进行光路的切换，使得包括时间戳的两路OSC信号在波长值之差小于预设的范围的同一根光纤中传输，从而根据该时间戳可准确地测量两个站点之间的单向传输时延。
本发明实施例还提供又一种站点，其硬件结构如图3或图6中的站点A中的OSC信号发送结构所示，该站点可包括控制器、与控制器连接的光路选择器、以及与光路选择器连接的光接口单元；在图3和图6中，该控制器为FPGA芯片，该光路选择器为一个2×2光 开关，该光接口单元为FIU。其中：
所述控制器，用于控制所述光路选择器工作在第一状态，以使所述光接口单元选择第一光纤向第二站点发送第一光监控信道OSC信号，所述第一OSC信号包括第一时间戳，所述第一时间戳指示第一站点发送所述第一OSC信号的第一发送时刻；
所述控制器，还用于控制所述光路选择器工作在第二状态，以使所述光接口单元在第二接收时刻选择所述第一光纤从所述第二站点接收第二OSC信号，所述第二OSC信号包括第二时间戳，所述第二时间戳指示所述第二站点接收所述第一OSC信号的第一接收时刻，以及所述第二站点发送所述第二OSC信号的第二发送时刻；所述第一OSC信号和所述第二OSC信号使用的波长值之差小于预设的范围；
所述控制器，还用于根据所述第一发送时刻、第一接收时刻、第二发送时刻和第二接收时刻计算所述第一站点和所述第二站点之间的单向传输时延。
在一种实现方式中，所述第一OSC信号和所述第二OSC信号使用的波长值之差为零。在该实现方式中，两个OSC信号使用的波长值之差为零，可以使得测量出的单向传输时延完全无误差。
在另一种实现方式中，所述单向传输时延为第一运算值与第二运算值之间的差值的一半，其中，所述第一运算值为第二接收时刻与第一发送时刻之间的差值，所述第二运算值为第二发送时刻与所述第一接收时刻之间的差值。在该实现方式中，单向传输时延是根据时间戳中记录的两个站点分别发送和接收OSC信号的时刻来计算得到的。
在又一种实现方式中，所述光接口单元还用于向所述第二站点发送所述单向传输时延。在该实现方式中，第一站点计算出单向传输时延后，向第二站点发送单向传输时延，以使第二站点能根据该单向传输时延和第一站点的时间准确地进行时间同步。
在又一种实现方式中，所述光接口单元还用于接收来自所述第二站点的确认消息，所述确认消息用于指示所述第二站点接收到所述第一OSC信号。在该实现方式中，第二站点在接收到第一OSC信号后，向第一站点发送确认消息，确认接收到该第一OSC信号，从而第一站点可以准确地进行光路的切换。当然，在另外的实现方式中，第一站点也可以在发送第一OSC信号的预设时间后进行光路的切换。
在又一种实现方式中，所述光路选择器为2×2光开关。在该实现方式中，通过2×2光开关可以简单地实现两种光路的切换。
在又一个实现方式中，所述光接口单元还用于向所述第二站点发送第三OSC信号，所述第三OSC信号包括更新的所述第一站点的时间。在该实现方式中，第一站点定期发送更新的第一站点的时间，第二站点根据更新的第一站点的时间和单向传输时延，可以实现与第一站点的时间同步。
根据本发明实施例提供的一种站点，通过光路选择器进行光路的切换，使得包括时间戳的两路OSC信号在波长值之差小于预设的范围的同一根光纤中传输，从而根据该时间戳可准确地测量两个站点之间的单向传输时延。
本发明实施例还提供又一种站点，其硬件结构如图3或图6中的站点B中的OSC信号发送结构所示，该站点可包括控制器、与控制器连接的光路选择器、以及与光路选择器连接的光接口单元；在图3和图6中，该控制器为FPGA芯片，该光路选择器为一个2×2光 开关，该光接口单元为FIU。其中：
所述控制器，用于控制所述光路选择器工作在第一状态，以使所述光接口单元选择第一光纤从第一站点接收第一光监控信道OSC信号，所述第一OSC信号包括第一时间戳，所述第一时间戳指示所述第一站点发送所述第一OSC信号的第一发送时刻；
所述控制器，还用于控制所述光路选择器工作在第二状态，以使所述光接口单元选择所述第一光纤向第一站点发送第二OSC信号，所述第二OSC信号包括第二时间戳，所述第二时间戳指示所述第二站点接收所述第一OSC信号的第一接收时刻，以及所述第二站点发送所述第二OSC信号的第二发送时刻；所述第一OSC信号和所述第二OSC信号使用的波长值之差小于预设的范围。
在一种实现方式中，所述第一OSC信号和所述第二OSC信号使用的波长值之差为零。在该实现方式中，两个OSC信号使用的波长值之差为零，可以使得测量出的单向传输时延完全无误差。
在另一种实现方式中，所述光接口单元还用于向所述第一站点发送确认消息，所述确认消息用于指示所述第二站点接收到所述第一OSC信号。在该实现方式中，第二站点在接收到第一OSC信号后，向第一站点发送确认消息，确认接收到该第一OSC信号，从而第一站点可以准确地进行光路的切换。当然，在另外的实现方式中，第一站点也可以在发送第一OSC信号的预设时间后进行光路的切换。
在又一个实现方式中，所述光路选择器具体用于根据所述第一光纤中光功率的变化，控制所述光路选择器工作在所述第二状态。在该实现方式中，无需第一站点通知第二站点光路的变化，第一站点在切换光路选择器的状态时，第二站点可以根据光纤中光功率的变化，切换第二站点的光路选择器的状态。具体地，该光纤中无光，光功率为零。
在又一种实现方式中，所述光接口单元还用于接收所述第一站点发送的单向传输时延。在该实现方式中，第一站点计算出单向传输时延后，向第二站点发送单向传输时延，第二站点能根据该单向传输时延和第一站点的时间进行时间同步。
在又一种实现方式中，所述控制器还用于根据所述单向传输时延和所述第一站点的时间，将所述第二站点的时间与所述第一站点的时间进行同步。在该实现方式中，第二站点能根据该单向传输时延和第一站点的时间准确地进行时间同步。
在又一种实现方式中，所述光接口单元还用于接收所述第一站点发送的第三OSC信号，所述第三OSC信号包括更新的第一站点的时间；所述第二站点根据所述更新的第一站点的时间和所述单向传输时延，对所述第二站点的时间进行更新。在该实现方式中，第一站点定期发送更新的第一站点的时间，第二站点根据更新的第一站点的时间和单向传输时延，可以准确地实现与第一站点的时间同步。
在又一个实现方式中，所述单向传输时延为第一运算值与第二运算值之间的差值的一半，其中，所述第一运算值为第二接收时刻与第一发送时刻之间的差值，所述第二运算值为第二发送时刻与所述第一接收时刻之间的差值。在该实现方式中，单向传输时延是根据时间戳中记录的两个站点分别发送和接收OSC信号的时刻来计算得到的。
在又一个实现方式中，所述光路选择器为2×2光开关。在该实现方式中，通过2×2光开关可以简单地实现两种光路的切换。
根据本发明实施例提供的一种站点，通过光路选择器进行光路的切换，使得包括时间戳的两路OSC信号在波长值之差小于预设的范围的同一根光纤中传输，从而根据该时间戳可准确地测量两个站点之间的单向传输时延。
本领域普通技术人员可以意识到，结合本文中所公开的实施例描述的各示例的单元及算法步骤，能够以电子硬件、或者计算机软件和电子硬件的结合来实现。这些功能究竟以硬件还是软件方式来执行，取决于技术方案的特定应用和设计约束条件。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能，但是这种实现不应认为超出本申请的范围。
所属领域的技术人员可以清楚地了解到，为描述的方便和简洁，上述描述的***、装置和单元的具体工作过程，可以参考前述方法实施例中的对应过程，在此不再赘述。
在本申请所提供的几个实施例中，应该理解到，所揭露的***、装置和方法，可以通过其它的方式实现。例如，以上所描述的装置实施例仅仅是示意性的，例如，所述单元的划分，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式，例如多个单元或组件可以结合或者可以集成到另一个***，或一些特征可以忽略，或不执行。另一点，所显示或讨论的相互之间的耦合或直接耦合或通信连接可以是通过一些接口，装置或单元的间接耦合或通信连接，可以是电性，机械或其它的形式。
所述作为分离部件说明的单元可以是或者也可以不是物理上分开的，作为单元显示的部件可以是或者也可以不是物理单元，即可以位于一个地方，或者也可以分布到多个网络单元上。可以根据实际的需要选择其中的部分或者全部单元来实现本实施例方案的目的。
另外，在本申请各个实施例中的各功能单元可以集成在一个处理单元中，也可以是各个单元单独物理存在，也可以两个或两个以上单元集成在一个单元中。
在上述实施例中，可以全部或部分地通过软件、硬件、固件或者其任意组合来实现。当使用软件实现时，可以全部或部分地以计算机程序产品的形式实现。所述计算机程序产品包括一个或多个计算机指令。在计算机上加载和执行所述计算机程序指令时，全部或部分地产生按照本发明实施例所述的流程或功能。所述计算机可以是通用计算机、专用计算机、计算机网络、或者其他可编程装置。所述计算机指令可以存储在计算机可读存储介质中，或者通过所述计算机可读存储介质进行传输。所述计算机指令可以从一个网站站点、计算机、服务器或数据中心通过有线(例如同轴电缆、光纤、数字用户线(digital subscriber line，DSL))或无线(例如红外、无线、微波等)方式向另一个网站站点、计算机、服务器或数据中心进行传输。所述计算机可读存储介质可以是计算机能够存取的任何可用介质或者是包含一个或多个可用介质集成的服务器、数据中心等数据存储设备。所述可用介质可以是磁性介质，(例如，软盘、硬盘、磁带)、光介质(例如，DVD)、或者半导体介质(例如固态硬盘(solid state disk，SSD))等。
本领域普通技术人员可以理解实现上述实施例方法中的全部或部分流程，该流程可以由计算机程序来指令相关的硬件完成，该程序可存储于计算机可读取存储介质中，该程序在执行时，可包括如上述各方法实施例的流程。而前述的存储介质包括：只读存储器(read-only memory，ROM)或随机存储存储器(random access memory，RAM)、磁碟或者光盘等各种可存储程序代码的介质。

Claims (28)

  1. 一种时延测量方法，其特征在于，所述方法包括：
    第一站点控制光路选择器工作在第一状态，以使所述第一站点选择第一光纤向第二站点发送第一光监控信道OSC信号，所述第一OSC信号包括第一时间戳，所述第一时间戳指示所述第一站点发送所述第一OSC信号的第一发送时刻；
    所述第一站点控制所述光路选择器工作在第二状态，以使所述第一站点在第二接收时刻选择所述第一光纤从第二站点接收第二OSC信号，所述第二OSC信号包括第二时间戳，所述第二时间戳指示所述第二站点接收所述第一OSC信号的第一接收时刻，以及所述第二站点发送所述第二OSC信号的第二发送时刻；所述第一OSC信号和所述第二OSC信号使用的波长值之差小于预设的范围；
    所述第一站点根据所述第一发送时刻、第一接收时刻、第二发送时刻和第二接收时刻计算所述第一站点和所述第二站点之间的单向传输时延。
  2. 如权利要求1所述的方法，其特征在于，所述第一OSC信号和所述第二OSC信号使用的波长值之差为零。
  3. 如权利要求1或2所述的方法，其特征在于，所述单向传输时延为第一运算值与第二运算值之间的差值的一半，其中，所述第一运算值为第二接收时刻与第一发送时刻之间的差值，所述第二运算值为第二发送时刻与所述第一接收时刻之间的差值。
  4. 如权利要求1至3任一项所述的方法，其特征在于，所述第一站点根据所述第一发送时刻、第一接收时刻、第二发送时刻和第二接收时刻计算所述第一站点和所述第二站点之间的单向传输时延之后，所述方法还包括：
    所述第一站点向所述第二站点发送所述单向传输时延。
  5. 如权利要求1至4任一项所述的方法，其特征在于，所述第一站点选择第一光纤向第二站点发送第一OSC信号之后，所述方法还包括：
    所述第一站点接收来自所述第二站点的确认消息，所述确认消息用于指示所述第二站点接收到所述第一OSC信号。
  6. 如权利要求1至5任一项所述的方法，其特征在于，所述光路选择器为2×2光开关。
  7. 一种时延测量方法，其特征在于，所述方法包括：
    所述第二站点控制光路选择器工作在第一状态，以使所述第二站点选择第一光纤从所述第一站点接收第一光监控信道OSC信号，所述第一OSC信号包括第一时间戳，所述第一时间戳指示所述第一站点发送所述第一OSC信号的第一发送时刻；
    所述第二站点控制所述光路选择器工作在第二状态，以使所述第二站点选择所述第一光纤向所述第一站点发送第二OSC信号，所述第二OSC信号包括第二时间戳，所述第二时间戳指示所述第二站点接收所述第一OSC信号的第一接收时刻，以及所述第二站点发送所述第二OSC信号的第二发送时刻；所述第一OSC信号和所述第二OSC信号使用的波长值之差小于预设的范围。
  8. 如权利要求7所述的方法，其特征在于，所述第一OSC信号和所述第二OSC信号 使用的波长值之差为零。
  9. 如权利要求7或8所述的方法，其特征在于，所述单向传输时延为第一运算值与第二运算值之间的差值的一半，其中，所述第一运算值为所述第一站点接收所述第二OSC信号的第二接收时刻与第一发送时刻之间的差值，所述第二运算值为第二发送时刻与所述第一接收时刻之间的差值。
  10. 如权利要求7至9任一项所述的方法，其特征在于，所述第二站点选择所述第一光纤向所述第一站点发送第二OSC信号之后，所述方法还包括：
    所述第二站点接收所述第一站点发送的单向传输时延。
  11. 如权利要求10所述的方法，其特征在于，所述第二站点接收所述第一站点发送的单向传输时延之后，所述方法还包括：
    所述第二站点根据所述单向传输时延和所述第一站点的时间，将所述第二站点的时间与所述第一站点的时间进行同步。
  12. 如权利要求7至11任一项所述的方法，其特征在于，所述第二站点控制所述光路选择器工作在第二状态，包括：
    所述第二站点根据所述第一光纤中光功率的变化，控制所述光路选择器工作在所述第二状态。
  13. 如权利要求7至12任一项所述的方法，其特征在于，所述第二站点选择第一光纤从所述第一站点接收第一OSC信号之后，所述方法还包括：
    所述第二站点向所述第一站点发送确认消息，所述确认消息用于指示所述第二站点接收到所述第一OSC信号。
  14. 如权利要求7至13任一项所述的方法，其特征在于，所述光路选择器为2×2光开关。
  15. 一种站点，其特征在于，包括：
    光路控制单元，用于控制光路选择器工作在第一状态；
    发送单元，用于选择第一光纤向第二站点发送第一光监控信道OSC信号，所述第一OSC信号包括第一时间戳，所述第一时间戳指示所述第一站点发送所述第一OSC信号的第一发送时刻；
    所述光路控制单元，还用于控制所述光路选择器工作在第二状态；
    接收单元，用于在第二接收时刻选择所述第一光纤从第二站点接收第二OSC信号，所述第二OSC信号包括第二时间戳，所述第二时间戳指示所述第二站点接收所述第一OSC信号的第一接收时刻，以及所述第二站点发送所述第二OSC信号的第二发送时刻；所述第一OSC信号和所述第二OSC信号使用的波长值之差小于预设的范围；
    计算单元，用于根据所述第一发送时刻、第一接收时刻、第二发送时刻和第二接收时刻计算所述第一站点和所述第二站点之间的单向传输时延。
  16. 如权利要求15所述的站点，其特征在于，所述第一OSC信号和所述第二OSC信号使用的波长值之差为零。
  17. 一种站点，其特征在于，包括：
    光路控制单元，用于控制光路选择器工作在第一状态；
    接收单元，用于选择第一光纤从所述第一站点接收第一光监控信道OSC信号，所述第一OSC信号包括第一时间戳，所述第一时间戳指示所述第一站点发送所述第一OSC信号的第一发送时刻；
    所述光路控制单元，还用于控制所述光路选择器工作在第二状态；
    发送单元，用于选择所述第一光纤向所述第一站点发送第二OSC信号，所述第二OSC信号包括第二时间戳，所述第二时间戳指示所述第二站点接收所述第一OSC信号的第一接收时刻，以及所述第二站点发送所述第二OSC信号的第二发送时刻；所述第一OSC信号和所述第二OSC信号使用的波长值之差小于预设的范围。
  18. 如权利要求17所述的站点，其特征在于，所述第一OSC信号和所述第二OSC信号使用的波长值之差为零。
  19. 如权利要求17或18所述的站点，其特征在于，所述接收单元，还用于接收所述第一站点发送的单向传输时延。
  20. 如权利要求19所述的站点，其特征在于，还包括：
    时间同步单元，用于根据所述单向传输时延和所述第一站点的时间，将所述第二站点的时间与所述第一站点的时间进行同步。
  21. 一种站点，其特征在于，包括：控制器、与所述控制器连接的光路选择器、以及与所述光路选择器连接的光接口单元；其中：
    所述控制器，用于控制所述光路选择器工作在第一状态，以使所述光接口单元选择第一光纤向第二站点发送第一光监控信道OSC信号，所述第一OSC信号包括第一时间戳，所述第一时间戳指示第一站点发送所述第一OSC信号的第一发送时刻；
    所述控制器，还用于控制所述光路选择器工作在第二状态，以使所述光接口单元在第二接收时刻选择所述第一光纤从所述第二站点接收第二OSC信号，所述第二OSC信号包括第二时间戳，所述第二时间戳指示所述第二站点接收所述第一OSC信号的第一接收时刻，以及所述第二站点发送所述第二OSC信号的第二发送时刻；所述第一OSC信号和所述第二OSC信号使用的波长值之差小于预设的范围；
    所述控制器，还用于根据所述第一发送时刻、第一接收时刻、第二发送时刻和第二接收时刻计算所述第一站点和所述第二站点之间的单向传输时延。
  22. 如权利要求21所述的站点，其特征在于，所述第一OSC信号和所述第二OSC信号使用的波长值之差为零。
  23. 如权利要求21或22所述的站点，其特征在于，所述单向传输时延为第一运算值与第二运算值之间的差值的一半，其中，所述第一运算值为第二接收时刻与第一发送时刻之间的差值，所述第二运算值为第二发送时刻与所述第一接收时刻之间的差值。
  24. 一种站点，其特征在于，包括：控制器、与所述控制器连接的光路选择器、以及与所述光路选择器连接的光接口单元；其中：
    所述控制器，用于控制所述光路选择器工作在第一状态，以使所述光接口单元选择第一光纤从第一站点接收第一光监控信道OSC信号，所述第一OSC信号包括第一时间戳，所述第一时间戳指示所述第一站点发送所述第一OSC信号的第一发送时刻；
    所述控制器，还用于控制所述光路选择器工作在第二状态，以使所述光接口单元选择 所述第一光纤向第一站点发送第二OSC信号，所述第二OSC信号包括第二时间戳，所述第二时间戳指示所述第二站点接收所述第一OSC信号的第一接收时刻，以及所述第二站点发送所述第二OSC信号的第二发送时刻；所述第一OSC信号和所述第二OSC信号使用的波长值之差小于预设的范围。
  25. 如权利要求24所述的站点，其特征在于，所述第一OSC信号和所述第二OSC信号使用的波长值之差为零。
  26. 如权利要求24或25所述的站点，其特征在于，所述单向传输时延为第一运算值与第二运算值之间的差值的一半，其中，所述第一运算值为所述第一站点接收所述第二OSC信号的第二接收时刻与第一发送时刻之间的差值，所述第二运算值为第二发送时刻与所述第一接收时刻之间的差值。
  27. 如权利要求24至26任一项所述的站点，其特征在于，所述光接口单元，还用于接收所述第一站点发送的单向传输时延。
  28. 如权利要求27所述的站点，其特征在于，所述控制器，还用于根据所述单向传输时延和所述第一站点的时间，将所述第二站点的时间与所述第一站点的时间进行同步。
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