WO2020172766A1 - 一种时间同步方法、装置及系统 - Google Patents

一种时间同步方法、装置及系统 Download PDF

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Publication number
WO2020172766A1
WO2020172766A1 PCT/CN2019/076041 CN2019076041W WO2020172766A1 WO 2020172766 A1 WO2020172766 A1 WO 2020172766A1 CN 2019076041 W CN2019076041 W CN 2019076041W WO 2020172766 A1 WO2020172766 A1 WO 2020172766A1
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WIPO (PCT)
Prior art keywords
time
difference
optical module
slave device
data
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PCT/CN2019/076041
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English (en)
French (fr)
Inventor
廖锦秋
刘翠
许剑波
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华为技术有限公司
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Application filed by 华为技术有限公司 filed Critical 华为技术有限公司
Priority to CN202211327216.XA priority Critical patent/CN115882991A/zh
Priority to CN201980091879.6A priority patent/CN113439397B/zh
Priority to EP19916582.0A priority patent/EP3917043A4/en
Priority to PCT/CN2019/076041 priority patent/WO2020172766A1/zh
Publication of WO2020172766A1 publication Critical patent/WO2020172766A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J3/00—Time-division multiplex systems
    • H04J3/02—Details
    • H04J3/06—Synchronising arrangements
    • H04J3/0635—Clock or time synchronisation in a network
    • H04J3/0638—Clock or time synchronisation among nodes; Internode synchronisation
    • H04J3/0658—Clock or time synchronisation among packet nodes
    • H04J3/0661—Clock or time synchronisation among packet nodes using timestamps
    • H04J3/0667—Bidirectional timestamps, e.g. NTP or PTP for compensation of clock drift and for compensation of propagation delays

Definitions

  • This application relates to the field of communication technology, and more specifically, to a time synchronization method, device and system.
  • the 1588 protocol also known as the precise time protocol (PTP) provides a set of time synchronization solutions.
  • PTP precise time protocol
  • FIG. 1 is a flowchart of the processing procedure of the 1588 protocol to realize time synchronization.
  • Step 1 The master device sends a synchronization message to the slave device, and the master device records the precise sending time t1 when the synchronization message leaves the master device.
  • Step 2 The master device encapsulates t1 into a follow message, and the master device sends the follow message carrying t1 to the slave device.
  • Step 3 When the slave device receives the synchronization message sent by the master device, the slave device records the precise arrival time t2 of the synchronization message to the slave device.
  • Step 4 The slave device sends a delay request message to the master device, and the slave device records the precise sending time t3 of the delay request message.
  • Step 5 When the master device receives the delay request message sent by the slave device, the master device records the precise arrival time t4 of the delay request message to the master device.
  • Step 6 The master device encapsulates t4 into a delayed request response message, and sends the delayed request response message carrying t4 to the slave device.
  • the slave device gets the four times t1, t2, t3, and t4.
  • t2-t1 downlink transmission delay+time deviation
  • t4-t3 uplink transmission delay-time deviation
  • the slave device can use the time offset to correct the local time, thereby ensuring that the local time of the slave device is the same as the local time of the master device.
  • the downlink transmission delay and the uplink transmission delay may be different, so the time deviation obtained by using the existing technology may not be the same. Accurate, which cannot guarantee that the local time of the slave device is synchronized with the local time of the master device.
  • the present application provides a time synchronization method, device, and system to measure the time deviation between the slave device and the master device in a more accurate manner, so that the slave device can use the time deviation to maintain time synchronization with the master device.
  • the first aspect provides a time synchronization method, which is applied to a slave device.
  • the slave device maintains time synchronization with the master device.
  • the master device includes a first optical module and a first network processor, and the slave device includes a second optical module and a second optical module.
  • the method includes: calculating a first one-way delay from the device, where the first one-way delay is used to indicate the sum of the transmission delay of the first optical module and the reception delay of the second optical module.
  • the slave device calculates the second one-way delay, and the second one-way delay is used to indicate the sum of the transmission delay of the second optical module and the reception delay of the first optical module.
  • the slave device calculates the difference between the first one-way delay and the second one-way delay to obtain the two-way delay difference.
  • the slave device calculates the time deviation between the slave device and the master device according to the two-way delay difference, the first sending time, the first receiving time, the second sending time, and the second receiving time.
  • the first sending time is the time at which the first network processor sends the synchronization message recorded by the master device
  • the first receiving time is the time at which the second network processor receives the synchronization message recorded by the slave device
  • the second sending time is the slave
  • the second receiving time is the time when the first network processor receives the delay request message recorded by the main device.
  • the slave device uses the time offset to adjust the local time of the slave device.
  • the slave device in the process of calculating the time deviation, considering that the first one-way delay is not the same as the second one-way delay, the slave device needs to measure the two-way delay difference, and according to the two-way delay difference , The first sending time, the first receiving time, the second sending time and the second receiving time calculate the time deviation between the slave device and the master device, and the slave device uses the time deviation to adjust the local time of the slave device.
  • the embodiment of the present application measures the time deviation between the slave device and the master device in a more accurate manner, which can ensure that the local time of the slave device is synchronized with the local time of the master device.
  • calculating the first one-way delay by the slave device includes: receiving the first difference sent by the master device from the slave device, where the first difference is the difference between the first time and the second time, The first time is the time when the first optical module receives the first data recorded by the main device, and the second time is the time when the first optical module outputs the second data recorded by the main device.
  • the slave device records the third time when the second optical module receives the second data.
  • the slave device records the fourth time when the second optical module outputs the first data.
  • the slave device calculates the difference between the fourth time and the third time to obtain the second difference.
  • the slave device calculates the difference between the second difference and the first difference to obtain the first one-way delay.
  • the first one-way delay is the sum of the transmission delay of the first optical module and the reception delay of the second optical module, and the difference between the second difference and the first difference is equal to the first optical module’s The sum of the transmission delay and the reception delay of the second optical module, so after the slave device obtains the first difference and the second difference, the slave device can use the first difference and the second difference to calculate the first order To delay.
  • calculating the second one-way delay by the slave device includes: the slave device records a fifth time when the second optical module receives the third data.
  • the slave device records the sixth time when the second optical module outputs the fourth data.
  • the slave device calculates the difference between the fifth time and the sixth time to obtain the third difference.
  • the slave device receives the fourth difference value sent by the master device.
  • the fourth difference value is the difference value between the eighth time and the seventh time.
  • the seventh time is the time when the first optical module received the fourth data recorded by the master device.
  • the eighth time is the time for the first optical module to output the third data recorded by the main device.
  • the slave device calculates the difference between the fourth difference and the third difference to obtain the second one-way delay.
  • the second one-way delay is the sum of the transmission delay of the second optical module and the reception delay of the first optical module
  • the difference between the fourth difference and the third difference is equal to the second optical module’s The sum of the transmission delay and the reception delay of the first optical module, so after the slave device obtains the third difference and the fourth difference, the slave device can use the third difference and the fourth difference to calculate the second order To delay.
  • calculating the first one-way delay by the slave device includes: receiving the first difference sent by the master device from the slave device, where the first difference is the difference between the first time and the second time, The first time is the time when the first optical module receives the first data recorded by the main device, and the second time is the time when the first optical module outputs the first data recorded by the main device.
  • the slave device records the third time when the second optical module receives the first data.
  • the slave device records the fourth time when the second optical module outputs the first data.
  • the slave device calculates the difference between the fourth time and the third time to obtain the second difference.
  • the slave device calculates the difference between the second difference and the first difference to obtain the first one-way delay.
  • the first one-way delay is the sum of the transmission delay of the first optical module and the reception delay of the second optical module, and the difference between the second difference and the first difference is equal to the first optical module’s The sum of the transmission delay and the reception delay of the second optical module, so after the slave device obtains the first difference and the second difference, the slave device can use the first difference and the second difference to calculate the first order To delay.
  • calculating the second one-way delay by the slave device includes: the slave device records a fifth time when the second optical module receives the second data.
  • the slave device records the sixth time when the second optical module outputs the second data.
  • the slave device calculates the difference between the fifth time and the sixth time to obtain the third difference.
  • the slave device receives the fourth difference value sent by the master device.
  • the fourth difference value is the difference value between the eighth time and the seventh time.
  • the seventh time is the time when the first optical module received the second data recorded by the master device.
  • the eighth time is the time for the first optical module to output the second data recorded by the main device.
  • the slave device calculates the difference between the fourth difference and the third difference to obtain the second one-way delay.
  • the second one-way delay is the sum of the transmission delay of the second optical module and the reception delay of the first optical module
  • the difference between the fourth difference and the third difference is equal to the second optical module’s The sum of the transmission delay and the reception delay of the first optical module, so after the slave device obtains the third difference and the fourth difference, the slave device can use the third difference and the fourth difference to calculate the second order To delay.
  • the slave device calculating the time deviation between the slave device and the master device according to the two-way delay difference, the first sending time, the first receiving time, the second sending time, and the second receiving time includes: The device calculates the time deviation between the slave device and the master device according to [(t2-t1)-(t4-t3)- ⁇ latency] ⁇ 2.
  • t1 is the first sending time
  • t2 is the first receiving time
  • t3 is the second sending time
  • t4 is the second receiving time
  • ⁇ latency is the two-way delay difference.
  • t2-t1 represents the sum of downlink transmission delay and time deviation
  • t4-t3 represents the sum of uplink transmission delay and time deviation
  • (t2-t1)-(t4-t3) (downlink transmission delay + time Deviation)
  • (uplink transmission delay-time deviation) (downlink transmission delay-uplink transmission delay) + 2 ⁇ time deviation
  • (downlink transmission delay-uplink transmission delay) is equivalent to the first one-way delay
  • the difference ⁇ latency with the second one-way delay, so the time deviation is equivalent to [(t2-t1)-(t4-t3)- ⁇ latency] ⁇ 2.
  • the slave device After the slave device obtains the two-way delay difference, the first sending time, the first receiving time, the second sending time, and the second receiving time, the slave device can use the formula [(t2-t1)-(t4-t3)- ⁇ latency ] ⁇ 2 Calculate the time deviation between the slave device and the master device.
  • measuring the first one-way delay by the slave device includes: the slave device records a third time when the second optical module receives the second data.
  • the slave device records the fourth time when the second optical module outputs the first data.
  • the slave device calculates the difference between the fourth time and the third time to obtain the second difference.
  • the slave device receives the first one-way delay sent by the master device, the first one-way delay is the difference between the second difference and the first difference, and the first difference is the difference between the first time and the second time ,
  • the first time is the time when the first optical module receives the first data recorded by the main device, and the second time is the time when the first optical module outputs the second data recorded by the main device.
  • the first one-way delay is the sum of the transmission delay of the first optical module and the reception delay of the second optical module, and the difference between the second difference and the first difference is equal to the first optical module’s The sum of the transmission delay and the reception delay of the second optical module, so after the master device obtains the first difference and the second difference, the master device can use the first difference and the second difference to calculate the first order To delay. After the master device calculates the first one-way delay, the master device will send the first one-way delay to the slave device.
  • measuring the second one-way delay by the slave device includes: the slave device records a fifth time when the second optical module receives the third data.
  • the slave device records the sixth time when the second optical module outputs the fourth data.
  • the slave device calculates the difference between the fifth time and the sixth time to obtain the third difference.
  • the slave device receives the second one-way delay sent by the master device, the second one-way delay is the difference between the fourth difference and the third difference, and the fourth difference is the difference between the eighth time and the seventh time ,
  • the seventh time is the time when the first optical module receives the fourth data recorded by the main device, and the eighth time is the time when the first optical module outputs the third data recorded by the main device.
  • the second one-way delay is the sum of the transmission delay of the second optical module and the reception delay of the first optical module, and the difference between the fourth difference and the third difference is equal to the second optical module’s The sum of the transmission delay and the reception delay of the first optical module, so after the master device obtains the third difference and the fourth difference, the master device can use the third difference and the fourth difference to calculate the second order To delay. After the master device calculates the second one-way delay, the master device will send the second one-way delay to the slave device.
  • measuring the first one-way delay by the slave device includes: the slave device records a third time when the second optical module receives the first data.
  • the slave device records the fourth time when the second optical module outputs the first data.
  • the slave device calculates the difference between the fourth time and the third time to obtain the second difference.
  • the slave device receives the first one-way delay sent by the master device, the first one-way delay is the difference between the second difference and the first difference, and the first difference is the difference between the first time and the second time ,
  • the first time is the time when the first optical module receives the first data recorded by the main device, and the second time is the time when the first optical module outputs the first data recorded by the main device.
  • the first one-way delay is the sum of the transmission delay of the first optical module and the reception delay of the second optical module, and the difference between the second difference and the first difference is equal to the first optical module’s The sum of the transmission delay and the reception delay of the second optical module, so after the master device obtains the first difference and the second difference, the master device can use the first difference and the second difference to calculate the first order To delay. After the master device calculates the first one-way delay, the master device will send the first one-way delay to the slave device.
  • measuring the second one-way delay by the slave device includes: the slave device records a fifth time when the second optical module receives the second data.
  • the slave device records the sixth time when the second optical module outputs the second data.
  • the slave device calculates the difference between the fifth time and the sixth time to obtain the third difference.
  • the slave device receives the second one-way delay sent by the master device, the second one-way delay is the difference between the fourth difference and the third difference, and the fourth difference is the difference between the eighth time and the seventh time ,
  • the seventh time is the time when the first optical module receives the second data recorded by the main device
  • the eighth time is the time when the first optical module outputs the second data recorded by the main device.
  • the second one-way delay is the sum of the transmission delay of the second optical module and the reception delay of the first optical module, and the difference between the fourth difference and the third difference is equal to the second optical module’s The sum of the transmission delay and the reception delay of the first optical module, so after the master device obtains the third difference and the fourth difference, the master device can use the third difference and the fourth difference to calculate the second order To delay. After the master device calculates the second one-way delay, the master device will send the second one-way delay to the slave device.
  • a second aspect provides a slave device that keeps time synchronization with a master device.
  • the master device includes a first network processor and a first optical module
  • the slave device includes a second network processor, a second optical module, and a measurement module.
  • the measurement module is used to calculate the first one-way delay
  • the first one-way delay is used to indicate the sum of the transmission delay of the first optical module and the reception delay of the second optical module.
  • It is also used to calculate the second one-way delay
  • the second one-way delay is used to indicate the sum of the transmission delay of the second optical module and the reception delay of the first optical module. It is also used to calculate the difference between the first one-way delay and the second one-way delay to obtain the two-way delay difference.
  • the first sending time is the time at which the first network processor sends the synchronization message recorded by the master device
  • the first receiving time is the time at which the second network processor receives the synchronization message recorded by the slave device
  • the second sending time is the slave
  • the second receiving time is the time when the first network processor receives the delay request message recorded by the main device.
  • the second network processor is used to adjust the local time of the slave device by using the time offset.
  • the measurement module is specifically configured to receive the first difference sent by the master device, the first difference is the difference between the first time and the second time, and the first time is recorded by the master device
  • the time when the first optical module receives the first data, and the second time is the time when the first optical module outputs the second data recorded by the main device.
  • the measurement module is specifically configured to record the fifth time when the second optical module receives the third data. Record the sixth time when the second optical module outputs the fourth data. Calculate the difference between the fifth time and the sixth time to obtain the third difference. Receive the fourth difference sent by the master device, the fourth difference is the difference between the eighth time and the seventh time, the seventh time is the time when the first optical module received the fourth data recorded by the master device, the eighth time The time when the first optical module recorded the third data output by the master device. Calculate the difference between the fourth difference and the third difference to obtain the second one-way delay.
  • the measurement module is specifically configured to receive the first difference sent by the master device, the first difference is the difference between the first time and the second time, and the first time is recorded by the master device
  • the time when the first optical module receives the first data, and the second time is the time when the first optical module outputs the first data recorded by the main device.
  • the measurement module is specifically configured to record the fifth time when the second optical module receives the second data. Record the sixth time when the second optical module outputs the second data. Calculate the difference between the fifth time and the sixth time to obtain the third difference.
  • Receive the fourth difference sent by the master device the fourth difference is the difference between the eighth time and the seventh time, the seventh time is the time when the first optical module received the second data recorded by the master device, the eighth time The time when the first optical module recorded the second data output by the master device. Calculate the difference between the fourth difference and the third difference to obtain the second one-way delay.
  • the second network processor and the second optical module are connected to each other, and the second optical module includes a measurement module.
  • the second network processor, the second optical module and the measurement module are connected in sequence.
  • the measurement module is specifically configured to calculate the time deviation between the slave device and the master device according to [(t2-t1)-(t4-t3)- ⁇ latency] ⁇ 2.
  • t1 is the first sending time
  • t2 is the first receiving time
  • t3 is the second sending time
  • t4 is the second receiving time
  • ⁇ latency is the two-way delay difference.
  • a system in a third aspect, includes a master device and a slave device.
  • the slave device maintains time synchronization with the master device.
  • the master device includes a first optical module and a first network processor.
  • the slave device includes a second optical module and a second optical module. 2.
  • Network processor and measurement module The measurement module is used to calculate the first one-way delay, and the first one-way delay is used to indicate the sum of the transmission delay of the first optical module and the reception delay of the second optical module. It is also used to calculate the second one-way delay, and the second one-way delay is used to indicate the sum of the transmission delay of the second optical module and the reception delay of the first optical module.
  • the first sending time is the time at which the first network processor sends the synchronization message recorded by the master device
  • the first receiving time is the time at which the second network processor receives the synchronization message recorded by the slave device
  • the second sending time is the slave
  • the second receiving time is the time when the first network processor receives the delay request message recorded by the main device.
  • the second network processor is used to adjust the local time of the slave device by using the time offset.
  • the measurement module is specifically configured to receive the first difference sent by the master device, the first difference is the difference between the first time and the second time, and the first time is recorded by the master device
  • the time when the first optical module receives the first data, and the second time is the time when the first optical module outputs the second data recorded by the main device.
  • the measurement module is specifically configured to record the fifth time when the second optical module receives the third data. Record the sixth time when the second optical module outputs the fourth data. Calculate the difference between the fifth time and the sixth time to obtain the third difference. Receive the fourth difference sent by the master device, the fourth difference is the difference between the eighth time and the seventh time, the seventh time is the time when the first optical module received the fourth data recorded by the master device, the eighth time The time when the first optical module recorded the third data output by the master device. Calculate the difference between the fourth difference and the third difference to obtain the second one-way delay.
  • the measurement module is specifically configured to receive the first difference sent by the master device, the first difference is the difference between the first time and the second time, and the first time is recorded by the master device
  • the time when the first optical module receives the first data, and the second time is the time when the first optical module outputs the first data recorded by the main device.
  • the measurement module is specifically configured to record the fifth time when the second optical module receives the second data. Record the sixth time when the second optical module outputs the second data. Calculate the difference between the fifth time and the sixth time to obtain the third difference.
  • Receive the fourth difference sent by the master device the fourth difference is the difference between the eighth time and the seventh time, the seventh time is the time when the first optical module received the second data recorded by the master device, the eighth time The time when the first optical module recorded the second data output by the master device. Calculate the difference between the fourth difference and the third difference to obtain the second one-way delay.
  • the second network processor and the second optical module are connected to each other, and the second optical module includes a measurement module.
  • the second network processor, the second optical module and the measurement module are connected in sequence.
  • the measurement module is specifically configured to calculate the time deviation between the slave device and the master device according to [(t2-t1)-(t4-t3)- ⁇ latency] ⁇ 2.
  • t1 is the first sending time
  • t2 is the first receiving time
  • t3 is the second sending time
  • t4 is the second receiving time
  • ⁇ latency is the two-way delay difference.
  • the fourth aspect provides a slave device, which needs to keep time synchronization with the master device.
  • the master device includes a first optical module and a first network processor
  • the slave device includes a second optical module and a second network processor.
  • the slave device also includes the following modules: a calculation module for calculating the first one-way delay from the device, and the first one-way delay is used to indicate the transmission delay of the first optical module and the receiving delay of the second optical module. with.
  • the second one-way delay is calculated, and the second one-way delay is used to indicate the sum of the transmission delay of the second optical module and the reception delay of the first optical module. Calculate the difference between the first one-way delay and the second one-way delay to obtain the two-way delay difference.
  • the first sending time is the time at which the first network processor sends the synchronization message recorded by the master device
  • the first receiving time is the time at which the second network processor receives the synchronization message recorded by the slave device
  • the second sending time is the slave
  • the second receiving time is the time when the first network processor receives the delay request message recorded by the main device.
  • the adjustment module is used to adjust the local time of the slave device using the time offset.
  • the calculation module is specifically configured to receive the first difference sent by the master device, the first difference is the difference between the first time and the second time, and the first time is recorded by the master device
  • the time when the first optical module receives the first data, and the second time is the time when the first optical module outputs the second data recorded by the main device.
  • the calculation module is specifically configured to record the fifth time when the second optical module receives the third data. Record the sixth time when the second optical module outputs the fourth data. Calculate the difference between the fifth time and the sixth time to obtain the third difference. Receive the fourth difference sent by the master device, the fourth difference is the difference between the eighth time and the seventh time, the seventh time is the time when the first optical module received the fourth data recorded by the master device, the eighth time The time when the first optical module recorded the third data output by the master device. Calculate the difference between the fourth difference and the third difference to obtain the second one-way delay.
  • the calculation module is specifically configured to receive the first difference sent by the master device, the first difference is the difference between the first time and the second time, and the first time is recorded by the master device The time when the first optical module receives the first data, and the second time is the time when the first optical module outputs the first data recorded by the main device. The third time when the second optical module receives the first data is recorded. Record the fourth time when the second optical module outputs the first data. Calculate the difference between the fourth time and the third time to obtain the second difference. Calculate the difference between the second difference and the first difference to obtain the first one-way delay.
  • the calculation module is specifically configured to record the fifth time when the second optical module receives the second data. Record the sixth time when the second optical module outputs the second data. Calculate the difference between the fifth time and the sixth time to obtain the third difference.
  • Receive the fourth difference sent by the master device the fourth difference is the difference between the eighth time and the seventh time, the seventh time is the time when the first optical module received the second data recorded by the master device, the eighth time The time when the first optical module recorded the second data output by the master device. Calculate the difference between the fourth difference and the third difference to obtain the second one-way delay.
  • the calculation module is specifically configured to calculate the time deviation between the slave device and the master device according to [(t2-t1)-(t4-t3)- ⁇ latency] ⁇ 2.
  • t1 is the first sending time
  • t2 is the first receiving time
  • t3 is the second sending time
  • t4 is the second receiving time
  • ⁇ latency is the two-way delay difference.
  • a fifth aspect provides a slave device, the slave device includes one or more processors and a memory, wherein the one or more processors are used to read software codes stored in the memory and execute the above-mentioned first aspect or the first aspect.
  • the slave device includes one or more processors and a memory, wherein the one or more processors are used to read software codes stored in the memory and execute the above-mentioned first aspect or the first aspect.
  • a sixth aspect provides a computer-readable storage medium that stores instructions in the computer-readable storage medium, and when it runs on a computer or a processor, the computer or the processor executes the above-mentioned first aspect or the first aspect. Any one of the possible implementation methods.
  • the seventh aspect provides a computer program product containing instructions, which when run on a computer or a processor, causes the computer or the processor to execute the method in the first aspect or any one of the possible implementation manners of the first aspect.
  • Figure 1 shows a flow chart of the processing process of the 1588 protocol to achieve time synchronization
  • FIG. 2 shows a schematic diagram of a master device sending data to a slave device according to an embodiment of this application
  • FIG. 3 shows a schematic diagram of sending data from a slave device to a master device according to an embodiment of this application
  • FIG. 4 shows a schematic diagram of a master device sending a synchronization message to a slave device according to an embodiment of this application
  • FIG. 5 shows a schematic diagram of a master device sending a follow message to a slave device according to an embodiment of this application
  • FIG. 6 shows a schematic diagram of a slave device sending a delay request message to a master device according to an embodiment of this application
  • FIG. 7 shows a schematic diagram of a master device sending a delay request response message to a slave device according to an embodiment of this application
  • FIG. 8 shows a flowchart of a time synchronization method provided by an embodiment of this application.
  • FIG. 9 shows a detailed flowchart of step S11 in FIG. 8.
  • FIG. 10 shows a detailed flowchart of step S12 in FIG. 8;
  • FIG. 11 shows a detailed flowchart of step S11 in FIG. 8;
  • FIG. 12 shows another schematic diagram of sending data from a master device to a slave device according to an embodiment of this application
  • FIG. 13 shows a detailed flowchart of step S12 in FIG. 8;
  • FIG. 14 shows another schematic diagram of sending data from a slave device to a master device according to an embodiment of this application
  • FIG. 15 shows a schematic diagram of a slave device provided by an embodiment of this application.
  • FIG. 16 shows a schematic diagram of another slave device provided by an embodiment of this application.
  • FIG. 17 shows a schematic diagram of another slave device provided by an embodiment of this application.
  • FIG. 18 shows a schematic diagram of another slave device provided by an embodiment of this application.
  • FIG. 19 shows a schematic diagram of a system provided by an embodiment of this application.
  • the embodiments of the present application provide a time synchronization method, which can solve the problems in the background technology and measure the time deviation between the slave device and the master device in a more accurate manner, thereby ensuring that the local time of the slave device is synchronized with the local time of the master device .
  • the time synchronization method provided in the embodiments of the present application may be applied to a device having a network processor and an optical module.
  • the device having a network processor and an optical module may be a switch, a router, or a base station.
  • Figure 2 shows a schematic diagram of the master device sending data to the slave device provided in this embodiment of the application
  • Figure 3 shows the slave device sending data to the master device provided in this embodiment of the application.
  • Figure 4 shows a schematic diagram of a master device sending a synchronization message to a slave device according to an embodiment of this application.
  • Figure 5 shows a schematic diagram of a master device sending a follow-up message to a slave device according to an embodiment of this application.
  • FIG. 6 shows a schematic diagram of a slave device sending a delay request message to a master device according to an embodiment of this application
  • FIG. 7 shows a master device sending a delay request response message to a slave device according to an embodiment of this application Schematic diagram.
  • the embodiments shown in FIGS. 2 and 3 describe how the slave device 2 obtains the two-way delay difference ⁇ latency
  • the embodiments shown in FIGS. 4 to 7 describe the slave device 2How to get (t2-t1)-(t4-t3).
  • slave 2 can use the formula [(t2-t1)-(t4-t3)- ⁇ latency] ⁇ 2 Calculate the time deviation, and the slave device 2 can use the time deviation to adjust the local time of the second network processor 21 of the slave device 2 to ensure that the second network processor 21 of the slave device 2 and the first network processor 11 of the master device 1 Keep time in sync.
  • the downlink transmission delay includes five parts.
  • the first part is the optical fiber transmission delay between the first network processor 11 and the first optical module 12
  • the second part is the first The transmission delay of an optical module 12
  • the third part is the optical fiber transmission delay between the first optical module 12 and the second optical module 22
  • the fourth part is the reception delay of the second optical module 22
  • the fifth part is The optical fiber transmission delay between the second optical module 22 and the second network processor 21 is delayed.
  • the uplink transmission delay includes five parts.
  • the first part is the optical fiber transmission delay between the second network processor 21 and the second optical module 22
  • the second part is the transmission delay of the second optical module 22
  • the third part is The optical fiber transmission delay between the second optical module 22 and the first optical module 12
  • the fourth part is the reception delay of the first optical module 12
  • the fifth part is the difference between the first optical module 12 and the first network processor 11 Optical fiber transmission delay between.
  • the embodiments shown in FIG. 2 and FIG. 3 describe how the slave device 2 obtains the two-way delay difference ⁇ latency.
  • the master device 1 includes a first network processor 11 and a first optical module 12, and the slave device 2 includes a second network processor 21 and a second optical module 22.
  • the following describes the execution process of obtaining the first one-way delay from the device 2 in conjunction with the embodiment shown in FIG. 2.
  • the first network processor 11 of the main device 1 sends the first data to the first optical module 12.
  • the main device 1 uses a timer to record the first data received by the first optical module 12 A time T1; the first optical module 12 of the master device 1 converts the first data into second data, the first optical module 12 of the master device 1 sends the second data to the second optical module 22 of the slave device 2, and the master device 1 Use a timer to record the second time T2 when the first optical module 12 outputs the second data.
  • the master device 1 calculates the difference between the first time T1 and the second time T2 to obtain the first difference (T1-T2).
  • the first difference (T1-T2) is sent to the slave 2.
  • the slave device 2 receives the first difference (T1-T2) sent by the master device 1.
  • the slave device 2 uses a timer to record the third time T3 when the second optical module 22 receives the second data, the second optical module 22 of the slave device 2 converts the second data into the first data, and the second optical module 22 of the slave device 2
  • the first data is sent to the second network processor 21, and the slave device 2 uses a timer to record the fourth time T4 when the second optical module 22 outputs the first data.
  • the slave device 2 calculates the difference between the fourth time T4 and the third time T3 to obtain the second difference (T4-T3), and the slave device 2 calculates the difference between the second difference (T4-T3) and the first difference (T1-T2) The difference results in the first one-way delay Td.
  • the transmission delay of the first optical module 12 of the master device 1 (T2-T1)
  • the reception delay of the second optical module 22 of the slave device 2 (T4-T3)
  • the second network processor 21 of the slave device 2 sends the third data to the second optical module 22, and the slave device 2 uses a timer to record the first time the second optical module 22 receives the third data.
  • the slave device 2 calculates the difference between the fifth time T5 and the sixth time T6 to obtain the third difference (T5-T6).
  • the master device 1 uses a timer to record the seventh time T7 when the first optical module 12 receives the fourth data, and the first optical module 12 of the master device 1 converts the fourth data into third data.
  • the first optical module 12 of the main device 1 sends the third data to the first network processor 11, and the main device 1 uses a timer to record the eighth time T8 when the first optical module 12 outputs the third data.
  • the master device 1 calculates the difference between the eighth time T8 and the seventh time T7 to obtain the fourth difference value (T8-T7), and the master device 1 sends the fourth difference value (T8-T7) to the slave device 2.
  • the slave device 2 calculates the difference between the fourth difference (T8-T7) and the third difference (T5-T6) to obtain the second one-way delay Tu.
  • the second one-way delay Tu may indicate the sum of the transmission delay of the second optical module 22 and the reception delay of the first optical module 12.
  • the slave device 2 can calculate the first one-way delay Td and the first one-way delay Td.
  • the difference between the two one-way delay Tu obtains the two-way delay difference ⁇ latency.
  • the first data, the second data, the third data and the fourth data may be the frame header of the data frame, and the first data, the second data, the third data and the fourth data
  • the data can also be the header of a data message.
  • the following describes the execution process of obtaining the first sending time t1, the first receiving time t2, the second sending time t3, and the second receiving time t4 from the device 2 in conjunction with the embodiments shown in FIGS. 4 to 7.
  • the first network processor 11 of the main device 1 sends the synchronization message to the first optical module 12, and the main device 1 records the first transmission time t1 when the first network processor 11 sends the synchronization message.
  • the first optical module 12 of the master device 1 sends the synchronization message to the second optical module 22 of the slave device 2, and the second optical module 22 of the slave device 2 sends the synchronization message to the second network processor 21 of the slave device 2.
  • the slave device 2 records the first receiving time t2 when the second network processor 21 receives the synchronization message.
  • the first network processor 11 of the master device 1 encapsulates the first transmission time t1 into the following message, and the first network processor 11 of the master device 1 passes through the first optical module 12 and the second optical module 12
  • the module 22 sends the follow message carrying t1 to the second network processor 21 of the slave device 2.
  • the second network processor 21 of the slave device 2 sends the delay request message to the second optical module 22, and the slave device 2 records the second sending time when the second network processor 21 sends the delay request message.
  • t3 The second optical module 22 of the slave device 2 sends the delay request message to the first optical module 12 of the master device 1, and the first optical module 12 of the master device 1 sends the delay request message to the first network processing of the master device 1.
  • the main device 1 records the second reception time t4 when the first network processor 11 receives the delay request message.
  • the first network processor 11 of the main device 1 encapsulates the second receiving time t4 into the delay request response message, and the first network processor 11 of the main device 1 passes the first optical module 12 and the second The second optical module 22 sends a delay request response message carrying t4 to the second network processor 21 of the slave device 2.
  • the slave device 2 calculates the two-way delay difference ⁇ latency, and the slave device 2 also obtains the first sending time t1, the first receiving time t2, the second sending time t3, and the second sending time t1. Receive time t4. At this time, the slave device 2 can calculate the time deviation between the slave device and the master device based on the formula [(t2-t1)-(t4-t3)- ⁇ latency] ⁇ 2, and the slave device 2 can use the time deviation to adjust The local time of the second network processor 21 of the slave device 2 ensures that the second network processor 21 of the slave device 2 and the first network processor 11 of the master device 1 maintain time synchronization. Since the time deviation calculated by the slave device 2 is more accurate, the second network processor 21 of the slave device 2 and the first network processor 11 of the master device 1 can maintain time synchronization with higher accuracy.
  • FIGS. 2 to 7 are used to enable readers to quickly understand the technical principles of the embodiments of the present application, and are not used to limit the protection scope of the embodiments of the present application.
  • the specific parameter values mentioned in the embodiments shown in FIGS. 2 to 7 can be changed according to the principles of the embodiments of the present application, and the protection scope of the embodiments of the present application is not limited to the specific parameter values already mentioned.
  • FIG. 8 shows a flowchart of a time synchronization method provided by an embodiment of this application.
  • the method shown in FIG. 8 can be applied to a slave device, and this method can ensure that the slave device needs to keep time synchronization with the master device.
  • the master device includes a first optical module and a first network processor
  • the slave device includes a second optical module and a second network processor.
  • the method shown in FIG. 8 includes the following steps.
  • Step S11 The slave device calculates the first one-way delay.
  • the first one-way delay is used to indicate the sum of the transmission delay of the first optical module and the reception delay of the second optical module.
  • step S11 the embodiment shown in FIG. 2 may be combined.
  • the embodiment shown in FIG. 2 introduces the execution process of calculating the first one-way delay from the device 2.
  • Step S12 The slave device calculates a second one-way delay.
  • the second one-way delay is used to indicate the sum of the transmission delay of the second optical module and the reception delay of the first optical module.
  • step S12 the embodiment shown in FIG. 3 may be combined.
  • the embodiment shown in FIG. 3 describes the execution process of calculating the second one-way delay from the device 2.
  • Step S13 The slave device calculates the difference between the first one-way delay and the second one-way delay to obtain a two-way delay difference.
  • Step S14 The slave device calculates the time deviation between the slave device and the master device according to the two-way delay difference, the first sending time, the first receiving time, the second sending time, and the second receiving time.
  • the first sending time is the time at which the first network processor sends the synchronization message recorded by the master device
  • the first receiving time is the time at which the second network processor receives the synchronization message recorded by the slave device
  • the second sending time is the slave
  • the second receiving time is the time when the first network processor receives the delay request message recorded by the main device.
  • step S14 the embodiments shown in Figs. 4 to 7 can be combined.
  • the embodiments shown in Figs. 4 to 7 introduce the first sending time t1 obtained from the device 2 and the first receiving The execution process of time t2, second sending time t3, and second receiving time t4.
  • the slave device After the slave device obtains the two-way delay difference, the first sending time, the first receiving time, the second sending time, and the second receiving time, the slave device can be based on the formula [(t2-t1)-(t4-t3)- ⁇ latency] ⁇ 2 Calculate the time deviation between the slave device and the master device.
  • t1 is the first sending time
  • t2 is the first receiving time
  • t3 is the second sending time
  • t4 the second receiving time
  • ⁇ latency is the two-way delay difference.
  • step S14 when calculating the time deviation between the slave device and the master device, the two-way delay difference is used to indicate the difference between the first one-way delay and the second one-way delay, so as to ensure that the final calculated The time deviation is more accurate.
  • Step S15 The slave device uses the time offset to adjust the local time of the slave device.
  • the slave device in the process of calculating the time offset in the embodiment of the present application, considering that the first one-way delay is different from the second one-way delay, the slave device needs to measure the two-way delay According to the two-way delay difference, the first sending time, the first receiving time, the second sending time and the second receiving time, the time deviation between the slave device and the master device is calculated.
  • the slave device uses the time deviation to adjust the local of the slave device time.
  • the embodiment of the present application measures the time deviation between the slave device and the master device in a more accurate manner, which can ensure that the local time of the slave device is synchronized with the local time of the master device.
  • FIG. 9 is a detailed flowchart of step S11 in FIG. 8.
  • the method shown in FIG. 9 includes the following steps.
  • Step S21 The slave device receives the first difference value sent by the master device.
  • the first difference is the difference between the first time and the second time.
  • the first time is the time when the first optical module recorded by the main device receives the first data
  • the second time is the first light recorded by the main device. The time when the module outputs the second data.
  • Step S22 The slave device records the third time when the second optical module receives the second data.
  • Step S23 The slave device records the fourth time when the second optical module outputs the first data.
  • Step S24 The slave device calculates the difference between the fourth time and the third time to obtain a second difference.
  • Step S25 The slave device calculates the difference between the second difference and the first difference to obtain the first one-way delay.
  • step S21 to step S25 the embodiment shown in FIG. 2 may be combined.
  • the embodiment shown in FIG. 2 describes the execution process of calculating the first one-way delay from the device 2.
  • the master device sends the first difference value to the slave device, so that after the slave device calculates the second difference value, the slave device can calculate the difference between the second difference value and the first difference value. Get the first one-way delay.
  • the first single delay can be calculated by the master device, so the slave device needs to send the second difference to the master device so that after the master device calculates the first difference, the master device can calculate the second difference The difference between the first difference and the first one-way delay is obtained, and the master device sends the first one-way delay to the slave device.
  • FIG. 10 is a detailed flowchart of step S12 in FIG. 8.
  • the method shown in FIG. 10 includes the following steps.
  • Step S31 The slave device records the fifth time when the second optical module receives the third data.
  • Step S32 The slave device records the sixth time when the second optical module outputs the fourth data.
  • Step S33 The slave device calculates the difference between the fifth time and the sixth time to obtain a third difference.
  • Step S34 The slave device receives the fourth difference value sent by the master device.
  • the fourth difference is the difference between the eighth time and the seventh time
  • the seventh time is the time when the first optical module recorded by the main device receives the fourth data
  • the eighth time is the first light recorded by the main device. The time when the module outputs the third data.
  • Step S35 The slave device calculates the difference between the fourth difference and the third difference to obtain the second one-way delay.
  • step S31 to step S35 the embodiment shown in FIG. 3 may be combined.
  • the embodiment shown in FIG. 3 introduces the execution process of calculating the second one-way delay from the device 2.
  • the master device sends the fourth difference value to the slave device, so that after the slave device calculates the third difference value, the slave device can calculate the difference between the fourth difference value and the third difference value. Get the second one-way delay.
  • the second single item delay can be calculated by the master device, so the slave device needs to send the third difference to the master device so that the master device can calculate the fourth difference after the fourth difference is calculated.
  • the difference between the third difference and the second one-way delay is obtained, and the master device sends the second one-way delay to the slave device.
  • FIG. 11 is a detailed flowchart of step S11 in FIG. 8.
  • the method shown in FIG. 11 includes the following steps.
  • Step S41 The slave device receives the first difference value sent by the master device.
  • the first difference is the difference between the first time and the second time.
  • the first time is the time when the first optical module recorded by the main device receives the first data
  • the second time is the first light recorded by the main device. The time when the module outputs the first data.
  • Step S42 The slave device records the third time when the second optical module receives the first data.
  • Step S43 The slave device records the fourth time when the second optical module outputs the first data.
  • Step S44 The slave device calculates the difference between the fourth time and the third time to obtain a second difference.
  • Step S45 The slave device calculates the difference between the second difference and the first difference to obtain the first one-way delay.
  • the master device sends the first difference value to the slave device, so that after the slave device calculates the second difference value, the slave device can calculate the difference between the second difference value and the first difference value. Get the first one-way delay.
  • the first single delay can be calculated by the master device, so the slave device needs to send the second difference to the master device so that after the master device calculates the first difference, the master device can calculate the second difference The difference between the first difference and the first one-way delay is obtained, and the master device sends the first one-way delay to the slave device.
  • step S41 to step S45 the embodiment shown in FIG. 12 may be combined.
  • the embodiment shown in FIG. 12 describes the execution process of calculating the first one-way delay from the device 2.
  • FIG. 12 shows another schematic diagram of sending data from a master device to a slave device according to an embodiment of this application.
  • the first network processor 11 of the main device 1 sends the first data to the first optical module 12.
  • the main device 1 uses a timer to record the first data received by the first optical module 12 A time T1; the first optical module 12 of the master device 1 sends the first data to the second optical module 22 of the slave device 2, and the master device 1 uses a timer to record the second time T2 when the first optical module 12 outputs the first data ,
  • the master device 1 calculates the difference between the first time T1 and the second time T2 to obtain the first difference (T1-T2), and the master device 1 sends the first difference (T1-T2) to the slave device 2.
  • the slave device 2 receives the first difference (T1-T2) sent by the master device 1.
  • the slave device 2 uses a timer to record the third time T3 when the second optical module 22 receives the first data, the second optical module 22 of the slave device 2 sends the first data to the second network processor 21, and the slave device 2 uses the timer
  • the fourth time T4 when the second optical module 22 outputs the first data is recorded.
  • the slave device 2 calculates the difference between the fourth time T4 and the third time T3 to obtain the second difference (T4-T3), and the slave device 2 calculates the difference between the second difference (T4-T3) and the first difference (T1-T2) The difference results in the first one-way delay Td.
  • the transmission delay of the first optical module 12 of the master device 1 (T2-T1)
  • the reception delay of the second optical module 22 of the slave device 2 (T4-T3)
  • the first data may be a header of a data frame, and the first data may also be a header of a data message.
  • FIG. 13 is a detailed flowchart of step S12 in FIG. 8.
  • the method shown in FIG. 13 includes the following steps.
  • Step S51 The slave device records the fifth time when the second optical module receives the second data.
  • Step S52 The slave device records the sixth time when the second optical module outputs the second data.
  • Step S53 The slave device calculates the difference between the fifth time and the sixth time to obtain a third difference.
  • Step S54 The slave device receives the fourth difference value sent by the master device.
  • the fourth difference is the difference between the eighth time and the seventh time
  • the seventh time is the time when the first optical module recorded by the main device receives the second data
  • the eighth time is the first light recorded by the main device. The time when the module outputs the second data.
  • Step S55 The slave device calculates the difference between the fourth difference and the third difference to obtain the second one-way delay.
  • the master device sends the fourth difference to the slave device, so that after the slave device calculates the third difference, the slave device can calculate the difference between the fourth difference and the third difference. Get the second one-way delay.
  • the second single item delay can be calculated by the master device, so the slave device needs to send the third difference to the master device so that the master device can calculate the fourth difference after the fourth difference is calculated.
  • the difference between the third difference and the second one-way delay is obtained, and the master device sends the second one-way delay to the slave device.
  • step S51 to step S55 the embodiment shown in FIG. 14 may be combined.
  • the embodiment shown in FIG. 14 describes the execution process of calculating the second one-way delay from the device 2.
  • FIG. 14 shows another schematic diagram of sending data from a slave device to a master device according to an embodiment of this application.
  • the second network processor 21 of the slave device 2 sends the second data to the second optical module 22, and the slave device 2 uses a timer to record the second data received by the second optical module 22.
  • the slave device 2 calculates the difference between the fifth time T5 and the sixth time T6 to obtain the third difference (T5-T6).
  • the master device 1 uses a timer to record the seventh time T7 when the first optical module 12 receives the second data, and the first optical module 12 of the master device 1 sends the second data to the first network.
  • the processor 11 and the main device 1 use a timer to record the eighth time T8 when the first optical module 12 outputs the second data.
  • the master device 1 calculates the difference between the eighth time T8 and the seventh time T7 to obtain the fourth difference value (T8-T7), and the master device 1 sends the fourth difference value (T8-T7) to the slave device 2.
  • Slave device 2 calculates the difference between the fourth difference (T8-T7) and the third difference (T5-T6) to obtain the second one-way delay Tu.
  • the second one-way delay Tu may indicate the sum of the transmission delay of the second optical module 22 and the reception delay of the first optical module 12.
  • the second data may be a header of a data frame, and the second data may also be a header of a data message.
  • FIG. 15 shows a schematic diagram of a slave device provided in an embodiment of this application.
  • the slave device shown in Figure 15 needs to keep time synchronization with the master device.
  • the master device includes a first optical module and a first network processor, and the slave device includes a second optical module and a second network processor.
  • the slave device also includes the following modules:
  • the calculation module 31 is used to calculate the first one-way delay from the device, the first one-way delay is used to indicate the sum of the transmission delay of the first optical module and the reception delay of the second optical module; calculate the second one-way delay Delay, the second one-way delay is used to indicate the sum of the transmission delay of the second optical module and the reception delay of the first optical module; calculate the difference between the first one-way delay and the second one-way delay to get the two-way Delay difference; calculate the time deviation between the slave device and the master device according to the two-way delay difference, first sending time, first receiving time, second sending time, and second receiving time; among them, the first sending time is the master device The recorded time when the first network processor sends the synchronization message, the first receiving time is the time when the second network processor receives the synchronization message recorded by the slave device, and the second sending time is the time when the second network processor recorded by the slave device sends The time for the delay request message, and the second receiving time is the time for the first network processor to receive the delay request message
  • the adjustment module 32 is used to adjust the local time of the slave device by using the time offset.
  • the adjustment module 32 please refer to the detailed description of step S15 in the method embodiment shown in FIG. 8 above.
  • the calculation module 31 is specifically configured to receive the first difference value sent by the master device, the first difference value is the difference value between the first time and the second time, and the first time is the main The time when the first optical module receives the first data recorded by the device, the second time is the time when the first optical module outputs the second data recorded by the main device; the third time when the second optical module receives the second data is recorded; the second time is recorded The fourth time when the optical module outputs the first data; calculate the difference between the fourth time and the third time to obtain the second difference; calculate the difference between the second difference and the first difference to obtain the first one-way delay.
  • the calculation module 31 please refer to the detailed description of step S21 to step S25 in the method embodiment shown in FIG. 9 above.
  • the calculation module 31 is specifically configured to record the fifth time when the second optical module receives the third data; record the sixth time when the second optical module outputs the fourth data; calculate the fifth time and The difference between the sixth time obtains the third difference; the fourth difference sent by the master device is received, and the fourth difference is the difference between the eighth time and the seventh time.
  • the seventh time is the first light recorded by the master device.
  • the time when the module receives the fourth data, the eighth time is the time when the first optical module outputs the third data recorded by the main device; the second one-way delay is obtained by calculating the difference between the fourth difference and the third difference.
  • the calculation module 31 please refer to the detailed description of step S31 to step S35 in the method embodiment shown in FIG. 10 above.
  • the calculation module 31 is specifically configured to receive the first difference value sent by the master device, the first difference value is the difference value between the first time and the second time, and the first time is the main The time when the first optical module receives the first data recorded by the device, the second time is the time when the first optical module outputs the first data recorded by the main device; the third time when the second optical module receives the first data; the second time is recorded The fourth time when the optical module outputs the first data; calculate the difference between the fourth time and the third time to obtain the second difference; calculate the difference between the second difference and the first difference to obtain the first one-way delay.
  • the calculation module 31 please refer to the detailed description of steps S41 to S45 in the method embodiment shown in FIG. 11 above.
  • the calculation module 31 is specifically configured to record the fifth time when the second optical module receives the second data; record the sixth time when the second optical module outputs the second data; calculate the fifth time and The difference between the sixth time obtains the third difference; the fourth difference sent by the master device is received, and the fourth difference is the difference between the eighth time and the seventh time.
  • the seventh time is the first light recorded by the master device.
  • the time when the module receives the second data, the eighth time is the time when the first optical module outputs the second data recorded by the main device; the difference between the fourth difference and the third difference is calculated to obtain the second one-way delay.
  • the calculation module 31 please refer to the detailed description of step S51 to step S55 in the method embodiment shown in FIG. 13 above.
  • the calculation module 31 is specifically configured to calculate the time deviation between the slave device and the master device according to [(t2-t1)-(t4-t3)- ⁇ latency] ⁇ 2; where t1 Is the first sending time, t2 is the first receiving time, t3 is the second sending time, t4 is the second receiving time, and ⁇ latency is the two-way delay difference.
  • t1 Is the first sending time
  • t2 is the first receiving time
  • t3 is the second sending time
  • t4 is the second receiving time
  • ⁇ latency is the two-way delay difference.
  • FIG. 16 is a schematic diagram of another slave device provided in an embodiment of this application.
  • the slave device 40 shown in FIG. 16 needs to keep time synchronization with the master device 50.
  • the master device 50 includes a first optical module 51 and a first network processor 52
  • the slave device 40 includes a second optical module 41, a second network processor 42 and a measurement module 43.
  • the second optical module 41 is connected to the second network processor respectively.
  • the processor 42 is connected to the measurement module 43.
  • the measuring module 43 is used to calculate the first one-way delay, and the first one-way delay is used to indicate the transmission delay of the first optical module 51 and the reception of the second optical module 41.
  • the measurement module 43 is specifically configured to receive the first difference value sent by the main device 50, the first difference value is the difference value between the first time and the second time, and the first time is The time when the first optical module 51 receives the first data recorded by the master device 50, and the second time is the time when the first optical module 51 outputs the second data recorded by the master device 50; the second time when the second optical module 41 receives the second data is recorded Three times; record the fourth time when the second optical module 41 outputs the first data; calculate the difference between the fourth time and the third time to obtain the second difference; calculate the difference between the second difference and the first difference to obtain the first order To delay.
  • the measurement module 43 is specifically configured to record the fifth time when the second optical module 41 receives the third data; record the sixth time when the second optical module 41 outputs the fourth data; calculate the fifth time
  • the third difference is obtained from the difference between the time and the sixth time; the fourth difference sent by the master device 50 is received, and the fourth difference is the difference between the eighth time and the seventh time, and the seventh time is recorded by the master device 50
  • the time when the first optical module 51 receives the fourth data, the eighth time is the time when the first optical module 51 outputs the third data recorded by the main device 50; the difference between the fourth difference and the third difference is calculated to obtain the second order To delay.
  • the measurement module 43 is specifically configured to receive the first difference value sent by the main device 50, the first difference value is the difference value between the first time and the second time, and the first time is The time when the first optical module 51 receives the first data recorded by the master device 50, the second time is the time when the first optical module 51 outputs the first data recorded by the master device 50; the second time when the second optical module 41 receives the first data Three times; record the fourth time when the second optical module 41 outputs the first data; calculate the difference between the fourth time and the third time to obtain the second difference; calculate the difference between the second difference and the first difference to obtain the first order To delay.
  • the measurement module 43 is specifically configured to record the fifth time when the second optical module 41 receives the second data; record the sixth time when the second optical module 41 outputs the second data; calculate the fifth time
  • the third difference is obtained from the difference between the time and the sixth time; the fourth difference sent by the master device 50 is received, and the fourth difference is the difference between the eighth time and the seventh time, and the seventh time is recorded by the master device 50
  • the time when the first optical module 51 receives the second data, the eighth time is the time when the first optical module 51 outputs the second data recorded by the main device 50; the difference between the fourth difference and the third difference is calculated to obtain the second order To delay.
  • the measurement module 43 is specifically configured to calculate the time deviation between the slave device 40 and the master device 50 according to [(t2-t1)-(t4-t3)- ⁇ latency] ⁇ 2; wherein , T1 is the first sending time, t2 is the first receiving time, t3 is the second sending time, t4 is the second receiving time, and ⁇ latency is the two-way delay difference.
  • FIG. 17 is a schematic diagram of another slave device provided in an embodiment of this application.
  • the slave device 60 shown in FIG. 17 needs to keep time synchronization with the master device 70.
  • the master device 70 includes a first optical module 71 and a first network processor 72
  • the slave device 60 includes a second optical module 61 and a second network processor 62
  • the second optical module 61 includes a measurement module 63
  • a second optical module 61 and the second network processor 62 are connected to each other.
  • the measurement module 43 shown in FIG. 16 is provided outside the second optical module 41, and the measurement module 63 shown in FIG. 17 is provided inside the second optical module 61, as shown in FIG.
  • the illustrated measurement module 43 implements the same functions as the measurement module 63 shown in FIG. 17.
  • the specific implementation of the measurement module 63 shown in FIG. 17, refer to the related description of the measurement module 43 shown in FIG. 16.
  • FIG. 18 is a schematic diagram of another slave device provided in an embodiment of this application.
  • the slave device 80 shown in FIG. 18 includes a network processor 81 and an optical module 82.
  • the optical module 82 includes a serializer 821, a client process 822, a digital signal processing process 823, a digital-to-analog converter 824, and a measurement module 825.
  • the following describes the process of the measurement module 825 calculating the transmission delay of the optical module 82.
  • the serializer 821 when the serializer 821 receives the customer service data sent by the network processor 81, the serializer 821 sends the customer service data to the client process 822 and the measurement module 825, respectively.
  • the measurement module 825 receives the customer service data sent by the serializer 821, the measurement module 825 records the first time T1, and the first time T1 is used to indicate the time when the customer service data enters the optical module 82.
  • the client process 822 converts the client service data into optical transmission data, and then sends the optical transmission data to the digital signal processing process 823.
  • the digital signal processing process 823 converts the optical transmission data into a baseband signal, and then sends the baseband signal to the digital-to-analog converter 824.
  • the digital-to-analog converter 824 converts the baseband signal into an analog signal, and then sends the analog signal to the main device 200 and the measurement module 825, respectively.
  • the measuring module 825 receives the analog signal sent by the digital-to-analog converter 824, the measuring module 825 records the second time T2, and the second time T2 is used to indicate the time when the analog signal leaves the optical module 82.
  • the measurement module 825 obtains the first time T1 when the customer service data enters the optical module 82 and the second time T2 when the analog signal leaves the optical module 82.
  • the measurement module 825 calculates the difference between the second time T2 and the first time T1 to obtain the optical The sending delay of module 82.
  • the principle of the measurement module 825 calculating the transmission delay of the optical module 82 is the same.
  • the measurement module 825 also needs to record the time when the data enters the optical module 82 and the data leaves the optical module. And calculate the difference between the time when the data leaves the optical module 82 and the time when the data enters the optical module 82 to obtain the receiving delay of the optical module 82.
  • the structure of the slave device 82 shown in FIG. 18 is only a specific implementation, and the slave device 82 may also be other types of structures, and the structure of the slave device 82 is not limited to the embodiment shown in FIG. 18.
  • the measurement module 825 shown in FIG. 18 is provided inside the optical module 82, and the measurement module 825 may also be provided outside the optical module 82.
  • FIG. 19 shows a schematic diagram of a system provided by an embodiment of this application.
  • the system shown in FIG. 19 includes a master device 90 and a slave device 100.
  • the slave device 100 needs to maintain time synchronization with the master device 90.
  • the master device 90 includes a first optical module 91 and a first network processor 92, and the slave device 100 includes The second optical module 101, the second network processor 102 and the measurement module 103.
  • the measurement module 103 is used to calculate the first one-way delay, and the first one-way delay is used to indicate the transmission delay of the first optical module 91 and the reception of the second optical module 101.
  • the sum of delays; also used to calculate the second one-way delay, the second one-way delay is used to indicate the sum of the transmission delay of the second optical module 101 and the reception delay of the first optical module 91; also used Calculate the difference between the first one-way delay and the second one-way delay to obtain the two-way delay difference; also used to calculate the two-way delay difference, the first sending time, the first receiving time, the second sending time, and the second receiving time Calculate the time deviation between the slave device 100 and the master device 90; wherein, the first sending time is the time when the first network processor 92 recorded by the master device 90 sends the synchronization message, and the first receiving time is the first time recorded by the slave device 100 Second, the time when the network processor 102 receives the synchronization message, the second sending time is the time when the second
  • the measurement module 103 is specifically configured to receive a first difference value sent by the main device 90, the first difference value is the difference value between the first time and the second time, and the first time is The time when the first optical module 91 receives the first data recorded by the master device 90, and the second time is the time when the first optical module 91 outputs the second data recorded by the master device 90; the second time when the second optical module 101 receives the second data is recorded Three times; record the fourth time when the second optical module 101 outputs the first data; calculate the difference between the fourth time and the third time to obtain the second difference; calculate the difference between the second difference and the first difference to obtain the first order To delay.
  • the measurement module 103 is specifically configured to record the fifth time when the second optical module 101 receives the third data; record the sixth time when the second optical module 101 outputs the fourth data; calculate the fifth time
  • the third difference is obtained from the difference between the time and the sixth time; the fourth difference sent by the master device 90 is received, and the fourth difference is the difference between the eighth time and the seventh time, and the seventh time is recorded by the master device 90
  • the time when the first optical module 91 receives the fourth data, and the eighth time is the time when the first optical module 91 outputs the third data recorded by the main device 90; the difference between the fourth difference and the third difference is calculated to obtain the second order To delay.
  • the measurement module 103 is specifically configured to receive a first difference value sent by the main device 90, the first difference value is the difference value between the first time and the second time, and the first time is The time when the first optical module 91 receives the first data recorded by the master device 90, the second time is the time when the first optical module 91 outputs the first data recorded by the master device 90; the second time when the second optical module 101 receives the first data is recorded Three times; record the fourth time when the second optical module 101 outputs the first data; calculate the difference between the fourth time and the third time to obtain the second difference; calculate the difference between the second difference and the first difference to obtain the first order To delay.
  • the measurement module 103 is specifically configured to record the fifth time when the second optical module 101 receives the second data; record the sixth time when the second optical module 101 outputs the second data; calculate the fifth time
  • the third difference is obtained from the difference between the time and the sixth time; the fourth difference sent by the master device 90 is received, and the fourth difference is the difference between the eighth time and the seventh time, and the seventh time is recorded by the master device 90
  • the time when the first optical module 91 receives the second data, the eighth time is the time when the first optical module 91 outputs the second data recorded by the main device 90; the difference between the fourth difference and the third difference is calculated to obtain the second order To delay.
  • the second network processor 102 is connected to the second optical module 101, and the second optical module 101 includes the measurement module 103; or, the second network processor 102, the second optical module 101, and The measurement modules 103 are connected in sequence.
  • the measuring module 103 is specifically configured to calculate the time deviation between the slave device 100 and the master device 90 according to [(t2-t1)-(t4-t3)- ⁇ latency] ⁇ 2; where , T1 is the first sending time, t2 is the first receiving time, t3 is the second sending time, t4 is the second receiving time, and ⁇ latency is the two-way delay difference.
  • the computer-readable medium includes a computer storage medium and a communication medium, where the communication medium includes any medium that facilitates the transfer of a computer program from one place to another.
  • the storage medium may be any available medium that can be accessed by a computer. Take this as an example but not limited to: computer readable media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage media or other magnetic storage devices, or can be used to carry or store instructions or data structures The desired program code and any other medium that can be accessed by the computer. In addition.
  • any connection can suitably become a computer-readable medium.
  • the software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave
  • coaxial cable , Fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, wireless and microwave are included in the fixing of the media.
  • Disk and disc include compact discs (CD), laser discs, optical discs, digital versatile discs (DVD), floppy discs and Blu-ray discs. Disks usually copy data magnetically, while discs The laser is used to optically copy data. The above combination should also be included in the protection scope of the computer-readable medium.

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Abstract

本申请公开了一种时间同步方法、装置及系统，该方法应用于从设备，从设备与主设备保持时间同步，主设备包括第一光模块和第一网络处理器，从设备包括第二光模块和第二网络处理器，该方法包括：从设备计算第一单向延时。从设备计算第二单向延时。从设备计算第一单向延时与第二单向延时之差得到双向延时差。从设备根据双向延时差、第一发送时间、第一接收时间、第二发送时间和第二接收时间计算从设备与主设备之间的时间偏差。从设备利用时间偏差调整从设备的本地时间。本申请以更加精准的方式测量从设备与主设备的时间偏差，可以保证从设备的本地时间与主设备的本地时间保持同步。

Description

一种时间同步方法、装置及系统 技术领域
本申请涉及通信技术领域，更具体的说，涉及时间同步方法、装置及系统。
背景技术
1588协议，又称精确时间协议(precise time protocol，PTP)，提供了一套时间同步的方案，下面简要介绍1588协议实现时间同步的工作原理。
请参见图1所示，图1所示的为1588协议实现时间同步的处理过程的流程图。
步骤1、主设备向从设备发送同步报文，主设备记录下同步报文离开主设备的精确发送时间t1。
步骤2、主设备将t1封装到跟随报文中，主设备将携带t1的跟随报文发送给从设备。
步骤3、在从设备接收到主设备发送的同步报文时，从设备会记录同步报文到达从设备的精确到达时间t2。
步骤4、从设备向主设备发送延迟请求报文，从设备记录下延迟请求报文的精确发送时间t3。
步骤5、在主设备接收到从设备发送的延迟请求报文时，主设备会记录延迟请求报文到达主设备的精确到达时间t4。
步骤6、主设备将t4封装到延迟请求响应报文中，并将携带t4的延迟请求响应报文发送给从设备。
此时，从设备便得到了t1、t2、t3和t4这四个时间。其中，t2-t1＝下行传输延时+时间偏差，t4-t3＝上行传输延时-时间偏差，所以(t2-t1)-(t4-t3)＝(下行传输延时+时间偏差)-(上行传输延时-时间偏差)＝(下行传输延时-上行传输延时)+2×时间偏差。在上述1588协议中，认为下行传输延时与上行传输延时是相同的，那么下行传输延时-上行传输延时＝0，所以时间偏差＝[(t2-t1)-(t4-t3)]÷2。在从设备根据t1、t2、t3和t4计算出时间偏差以后，从设备便可以利用该时间偏差来修正本地时间，从而保证从设备的本地时间与主设备的本地时间相同。
但是，在实际场景中，由于主设备的光模块和从设备的光模块的内部原因，使得下行传输延时与上行传输延时可能并不相同，所以采用现有技术得到的时间偏差可能并不准确，从而无法保证从设备的本地时间与主设备的本地时间保持同步。
发明内容
本申请提供一种时间同步方法、装置及系统，以更加精准的方式测量从设备与主设备的时间偏差，进而使得从设备可以利用该时间偏差与主设备保持时间同步。
第一方面提供了一种时间同步方法，该方法应用于从设备，从设备与主设备保持时间同步，主设备包括第一光模块和第一网络处理器，从设备包括第二光模块和第二网络处理器，该方法包括：从设备计算第一单向延时，第一单向延时用于指示第一光模块的发送延时与第二光模块的接收延时之和。从设备计算第二单向延时，第二单向延时用于指示第二 光模块的发送延时与第一光模块的接收延时之和。从设备计算第一单向延时与第二单向延时之差得到双向延时差。从设备根据双向延时差、第一发送时间、第一接收时间、第二发送时间和第二接收时间计算从设备与主设备之间的时间偏差。其中，第一发送时间为主设备记录的第一网络处理器发送同步报文的时间，第一接收时间为从设备记录的第二网络处理器接收同步报文的时间，第二发送时间为从设备记录的第二网络处理器发送延时请求报文的时间，第二接收时间为主设备记录的第一网络处理器接收延时请求报文的时间。从设备利用时间偏差调整从设备的本地时间。
在第一方面中，在计算时间偏差的过程中，考虑到第一单向延时与第二单向延时并不相同的情况，从设备需要测量双向延时差，并根据双向延时差、第一发送时间、第一接收时间、第二发送时间和第二接收时间计算从设备与主设备之间的时间偏差，从设备利用时间偏差调整从设备的本地时间。本申请实施例以更加精准的方式测量从设备与主设备的时间偏差，可以保证从设备的本地时间与主设备的本地时间保持同步。
在一种可能的实现方式中，从设备计算第一单向延时包括：从设备接收主设备发送的第一差值，第一差值为第一时间与第二时间之间的差值，第一时间为主设备记录的第一光模块接收第一数据的时间，第二时间为主设备记录的第一光模块输出第二数据的时间。从设备记录第二光模块接收第二数据的第三时间。从设备记录第二光模块输出第一数据的第四时间。从设备计算第四时间与第三时间之差得到第二差值。从设备计算第二差值与第一差值之差得到第一单向延时。其中，由于第一单向延时为第一光模块的发送延时与第二光模块的接收延时之和，而且，第二差值与第一差值之差等同于第一光模块的发送延时与第二光模块的接收延时之和，所以在从设备得到第一差值和第二差值以后，从设备便可以利用第一差值和第二差值计算出第一单向延时。
在一种可能的实现方式中，从设备计算第二单向延时包括：从设备记录第二光模块接收第三数据的第五时间。从设备记录第二光模块输出第四数据的第六时间。从设备计算第五时间与第六时间之差得到第三差值。从设备接收主设备发送的第四差值，第四差值为第八时间与第七时间之间的差值，第七时间为主设备记录的第一光模块接收第四数据的时间，第八时间为主设备记录的第一光模块输出第三数据的时间。从设备计算第四差值与第三差值之差得到第二单向延时。其中，由于第二单向延时为第二光模块的发送延时与第一光模块的接收延时之和，而且，第四差值与第三差值之差等同于第二光模块的发送延时与第一光模块的接收延时之和，所以在从设备得到第三差值和第四差值以后，从设备便可以利用第三差值和第四差值计算出第二单向延时。
在一种可能的实现方式中，从设备计算第一单向延时包括：从设备接收主设备发送的第一差值，第一差值为第一时间与第二时间之间的差值，第一时间为主设备记录的第一光模块接收第一数据的时间，第二时间为主设备记录的第一光模块输出第一数据的时间。从设备记录第二光模块接收第一数据的第三时间。从设备记录第二光模块输出第一数据的第四时间。从设备计算第四时间与第三时间之差得到第二差值。从设备计算第二差值与第一差值之差得到第一单向延时。其中，由于第一单向延时为第一光模块的发送延时与第二光模块的接收延时之和，而且，第二差值与第一差值之差等同于第一光模块的发送延时与第二光模块的接收延时之和，所以在从设备得到第一差值和第二差值以后，从设备便可以利用第一差值和第二差值计算出第一单向延时。
在一种可能的实现方式中，从设备计算第二单向延时包括：从设备记录第二光模块接收第二数据的第五时间。从设备记录第二光模块输出第二数据的第六时间。从设备计算第五时间与第六时间之差得到第三差值。从设备接收主设备发送的第四差值，第四差值为第八时间与第七时间之间的差值，第七时间为主设备记录的第一光模块接收第二数据的时间，第八时间为主设备记录的第一光模块输出第二数据的时间。从设备计算第四差值与第三差值之差得到第二单向延时。其中，由于第二单向延时为第二光模块的发送延时与第一光模块的接收延时之和，而且，第四差值与第三差值之差等同于第二光模块的发送延时与第一光模块的接收延时之和，所以在从设备得到第三差值和第四差值以后，从设备便可以利用第三差值和第四差值计算出第二单向延时。
在一种可能的实现方式中，从设备根据双向延时差、第一发送时间、第一接收时间、第二发送时间和第二接收时间计算从设备与主设备之间的时间偏差包括：从设备根据[(t2-t1)-(t4-t3)-Δlatency]÷2计算从设备与主设备之间的时间偏差。其中，t1为第一发送时间，t2为第一接收时间，t3为第二发送时间，t4为第二接收时间，Δlatency为双向延时差。其中，t2-t1表示下行传输延时与时间偏差之和，t4-t3表示上行传输延时与时间偏差之和，所以(t2-t1)-(t4-t3)＝(下行传输延时+时间偏差)-(上行传输延时-时间偏差)＝(下行传输延时-上行传输延时)+2×时间偏差，由于(下行传输延时-上行传输延时)等同于第一单向延时与第二单向延时之差Δlatency，所以时间偏差等同于[(t2-t1)-(t4-t3)-Δlatency]÷2。在从设备得到双向延时差、第一发送时间、第一接收时间、第二发送时间和第二接收时间以后，从设备便可以根据公式[(t2-t1)-(t4-t3)-Δlatency]÷2计算出从设备与主设备的时间偏差。
在一种可能的实现方式中，从设备测量第一单向延时包括：从设备记录第二光模块接收第二数据的第三时间。从设备记录第二光模块输出第一数据的第四时间。从设备计算第四时间与第三时间之差得到第二差值。从设备向主设备发送的第二差值。从设备接收主设备发送的第一单向延时，第一单向延时为第二差值与第一差值之差，第一差值为第一时间与第二时间之间的差值，第一时间为主设备记录的第一光模块接收第一数据的时间，第二时间为主设备记录的第一光模块输出第二数据的时间。其中，由于第一单向延时为第一光模块的发送延时与第二光模块的接收延时之和，而且，第二差值与第一差值之差等同于第一光模块的发送延时与第二光模块的接收延时之和，所以在主设备得到第一差值和第二差值以后，主设备便可以利用第一差值和第二差值计算出第一单向延时。在主设备计算出第一单向延时以后，主设备便会将第一单向延时发送给从设备。
在一种可能的实现方式中，从设备测量第二单向延时包括：从设备记录第二光模块接收第三数据的第五时间。从设备记录第二光模块输出第四数据的第六时间。从设备计算第五时间与第六时间之差得到第三差值。从设备向主设备发送的第三差值。从设备接收主设备发送的第二单向延时，第二单向延时为第四差值与第三差值之差，第四差值为第八时间与第七时间之间的差值，第七时间为主设备记录的第一光模块接收第四数据的时间，第八时间为主设备记录的第一光模块输出第三数据的时间。其中，由于第二单向延时为第二光模块的发送延时与第一光模块的接收延时之和，而且，第四差值与第三差值之差等同于第二光模块的发送延时与第一光模块的接收延时之和，所以在主设备得到第三差值和第四差值以后，主设备便可以利用第三差值和第四差值计算出第二单向延时。在主设备计算出第 二单向延时以后，主设备便会将第二单向延时发送给从设备。
在一种可能的实现方式中，从设备测量第一单向延时包括：从设备记录第二光模块接收第一数据的第三时间。从设备记录第二光模块输出第一数据的第四时间。从设备计算第四时间与第三时间之差得到第二差值。从设备向主设备发送的第二差值。从设备接收主设备发送的第一单向延时，第一单向延时为第二差值与第一差值之差，第一差值为第一时间与第二时间之间的差值，第一时间为主设备记录的第一光模块接收第一数据的时间，第二时间为主设备记录的第一光模块输出第一数据的时间。其中，由于第一单向延时为第一光模块的发送延时与第二光模块的接收延时之和，而且，第二差值与第一差值之差等同于第一光模块的发送延时与第二光模块的接收延时之和，所以在主设备得到第一差值和第二差值以后，主设备便可以利用第一差值和第二差值计算出第一单向延时。在主设备计算出第一单向延时以后，主设备便会将第一单向延时发送给从设备。
在一种可能的实现方式中，从设备测量第二单向延时包括：从设备记录第二光模块接收第二数据的第五时间。从设备记录第二光模块输出第二数据的第六时间。从设备计算第五时间与第六时间之差得到第三差值。从设备向主设备发送的第三差值。从设备接收主设备发送的第二单向延时，第二单向延时为第四差值与第三差值之差，第四差值为第八时间与第七时间之间的差值，第七时间为主设备记录的第一光模块接收第二数据的时间，第八时间为主设备记录的第一光模块输出第二数据的时间。其中，由于第二单向延时为第二光模块的发送延时与第一光模块的接收延时之和，而且，第四差值与第三差值之差等同于第二光模块的发送延时与第一光模块的接收延时之和，所以在主设备得到第三差值和第四差值以后，主设备便可以利用第三差值和第四差值计算出第二单向延时。在主设备计算出第二单向延时以后，主设备便会将第二单向延时发送给从设备。
第二方面提供了一种从设备，该从设备与主设备保持时间同步，主设备包括第一网络处理器和第一光模块，从设备包括第二网络处理器、第二光模块和测量模块。其中，测量模块，用于计算第一单向延时，第一单向延时用于指示第一光模块的发送延时与第二光模块的接收延时之和。还用于计算第二单向延时，第二单向延时用于指示第二光模块的发送延时与第一光模块的接收延时之和。还用于计算第一单向延时与第二单向延时之差得到双向延时差。还用于根据双向延时差、第一发送时间、第一接收时间、第二发送时间和第二接收时间计算从设备与主设备之间的时间偏差。其中，第一发送时间为主设备记录的第一网络处理器发送同步报文的时间，第一接收时间为从设备记录的第二网络处理器接收同步报文的时间，第二发送时间为从设备记录的第二网络处理器发送延时请求报文的时间，第二接收时间为主设备记录的第一网络处理器接收延时请求报文的时间。第二网络处理器，用于利用时间偏差调整从设备的本地时间。
在一种可能的实现方式中，测量模块，具体用于接收主设备发送的第一差值，第一差值为第一时间与第二时间之间的差值，第一时间为主设备记录的第一光模块接收第一数据的时间，第二时间为主设备记录的第一光模块输出第二数据的时间。记录第二光模块接收第二数据的第三时间。记录第二光模块输出第一数据的第四时间。计算第四时间与第三时间之差得到第二差值。计算第二差值与第一差值之差得到第一单向延时。
在一种可能的实现方式中，测量模块，具体用于记录第二光模块接收第三数据的第五时间。记录第二光模块输出第四数据的第六时间。计算第五时间与第六时间之差得到第三 差值。接收主设备发送的第四差值，第四差值为第八时间与第七时间之间的差值，第七时间为主设备记录的第一光模块接收第四数据的时间，第八时间为主设备记录的第一光模块输出第三数据的时间。计算第四差值与第三差值之差得到第二单向延时。
在一种可能的实现方式中，测量模块，具体用于接收主设备发送的第一差值，第一差值为第一时间与第二时间之间的差值，第一时间为主设备记录的第一光模块接收第一数据的时间，第二时间为主设备记录的第一光模块输出第一数据的时间。记录第二光模块接收第一数据的第三时间。记录第二光模块输出第一数据的第四时间。计算第四时间与第三时间之差得到第二差值。计算第二差值与第一差值之差得到第一单向延时。
在一种可能的实现方式中，测量模块，具体用于记录第二光模块接收第二数据的第五时间。记录第二光模块输出第二数据的第六时间。计算第五时间与第六时间之差得到第三差值。接收主设备发送的第四差值，第四差值为第八时间与第七时间之间的差值，第七时间为主设备记录的第一光模块接收第二数据的时间，第八时间为主设备记录的第一光模块输出第二数据的时间。计算第四差值与第三差值之差得到第二单向延时。
在一种可能的实现方式中，第二网络处理器与第二光模块相互连接，第二光模块包括测量模块。或者，第二网络处理器、第二光模块和测量模块依次连接。
在一种可能的实现方式中，测量模块，具体用于根据[(t2-t1)-(t4-t3)-Δlatency]÷2计算从设备与主设备之间的时间偏差。其中，t1为第一发送时间，t2为第一接收时间，t3为第二发送时间，t4为第二接收时间，Δlatency为双向延时差。
第三方面提供了一种系统，该系统包括主设备和从设备，从设备与主设备保持时间同步，主设备包括第一光模块和第一网络处理器，从设备包括第二光模块、第二网络处理器和测量模块。其中，测量模块，用于计算第一单向延时，第一单向延时用于指示第一光模块的发送延时与第二光模块的接收延时之和。还用于计算第二单向延时，第二单向延时用于指示第二光模块的发送延时与第一光模块的接收延时之和。还用于计算第一单向延时与第二单向延时之差得到双向延时差。还用于根据双向延时差、第一发送时间、第一接收时间、第二发送时间和第二接收时间计算从设备与主设备之间的时间偏差。其中，第一发送时间为主设备记录的第一网络处理器发送同步报文的时间，第一接收时间为从设备记录的第二网络处理器接收同步报文的时间，第二发送时间为从设备记录的第二网络处理器发送延时请求报文的时间，第二接收时间为主设备记录的第一网络处理器接收延时请求报文的时间。第二网络处理器，用于利用时间偏差调整从设备的本地时间。
在一种可能的实现方式中，测量模块，具体用于接收主设备发送的第一差值，第一差值为第一时间与第二时间之间的差值，第一时间为主设备记录的第一光模块接收第一数据的时间，第二时间为主设备记录的第一光模块输出第二数据的时间。记录第二光模块接收第二数据的第三时间。记录第二光模块输出第一数据的第四时间。计算第四时间与第三时间之差得到第二差值。计算第二差值与第一差值之差得到第一单向延时。
在一种可能的实现方式中，测量模块，具体用于记录第二光模块接收第三数据的第五时间。记录第二光模块输出第四数据的第六时间。计算第五时间与第六时间之差得到第三差值。接收主设备发送的第四差值，第四差值为第八时间与第七时间之间的差值，第七时间为主设备记录的第一光模块接收第四数据的时间，第八时间为主设备记录的第一光模块输出第三数据的时间。计算第四差值与第三差值之差得到第二单向延时。
在一种可能的实现方式中，测量模块，具体用于接收主设备发送的第一差值，第一差值为第一时间与第二时间之间的差值，第一时间为主设备记录的第一光模块接收第一数据的时间，第二时间为主设备记录的第一光模块输出第一数据的时间。记录第二光模块接收第一数据的第三时间。记录第二光模块输出第一数据的第四时间。计算第四时间与第三时间之差得到第二差值。计算第二差值与第一差值之差得到第一单向延时。
在一种可能的实现方式中，测量模块，具体用于记录第二光模块接收第二数据的第五时间。记录第二光模块输出第二数据的第六时间。计算第五时间与第六时间之差得到第三差值。接收主设备发送的第四差值，第四差值为第八时间与第七时间之间的差值，第七时间为主设备记录的第一光模块接收第二数据的时间，第八时间为主设备记录的第一光模块输出第二数据的时间。计算第四差值与第三差值之差得到第二单向延时。
在一种可能的实现方式中，第二网络处理器与第二光模块相互连接，第二光模块包括测量模块。或者，第二网络处理器、第二光模块和测量模块依次连接。
在一种可能的实现方式中，测量模块，具体用于根据[(t2-t1)-(t4-t3)-Δlatency]÷2计算从设备与主设备之间的时间偏差。其中，t1为第一发送时间，t2为第一接收时间，t3为第二发送时间，t4为第二接收时间，Δlatency为双向延时差。
第四方面提供了一种从设备，该从设备需要与主设备保持时间同步。其中，主设备包括第一光模块和第一网络处理器，从设备包括第二光模块和第二网络处理器。该从设备还包括以下模块：计算模块，用于从设备计算第一单向延时，第一单向延时用于指示第一光模块的发送延时与第二光模块的接收延时之和。计算第二单向延时，第二单向延时用于指示第二光模块的发送延时与第一光模块的接收延时之和。计算第一单向延时与第二单向延时之差得到双向延时差。根据双向延时差、第一发送时间、第一接收时间、第二发送时间和第二接收时间计算从设备与主设备之间的时间偏差。其中，第一发送时间为主设备记录的第一网络处理器发送同步报文的时间，第一接收时间为从设备记录的第二网络处理器接收同步报文的时间，第二发送时间为从设备记录的第二网络处理器发送延时请求报文的时间，第二接收时间为主设备记录的第一网络处理器接收延时请求报文的时间。调整模块，用于利用时间偏差调整从设备的本地时间。
在一种可能的实现方式中，计算模块，具体用于接收主设备发送的第一差值，第一差值为第一时间与第二时间之间的差值，第一时间为主设备记录的第一光模块接收第一数据的时间，第二时间为主设备记录的第一光模块输出第二数据的时间。记录第二光模块接收第二数据的第三时间。记录第二光模块输出第一数据的第四时间。计算第四时间与第三时间之差得到第二差值。计算第二差值与第一差值之差得到第一单向延时。
在一种可能的实现方式中，计算模块，具体用于记录第二光模块接收第三数据的第五时间。记录第二光模块输出第四数据的第六时间。计算第五时间与第六时间之差得到第三差值。接收主设备发送的第四差值，第四差值为第八时间与第七时间之间的差值，第七时间为主设备记录的第一光模块接收第四数据的时间，第八时间为主设备记录的第一光模块输出第三数据的时间。计算第四差值与第三差值之差得到第二单向延时。
在一种可能的实现方式中，计算模块，具体用于接收主设备发送的第一差值，第一差值为第一时间与第二时间之间的差值，第一时间为主设备记录的第一光模块接收第一数据的时间，第二时间为主设备记录的第一光模块输出第一数据的时间。记录第二光模块接收 第一数据的第三时间。记录第二光模块输出第一数据的第四时间。计算第四时间与第三时间之差得到第二差值。计算第二差值与第一差值之差得到第一单向延时。
在一种可能的实现方式中，计算模块，具体用于记录第二光模块接收第二数据的第五时间。记录第二光模块输出第二数据的第六时间。计算第五时间与第六时间之差得到第三差值。接收主设备发送的第四差值，第四差值为第八时间与第七时间之间的差值，第七时间为主设备记录的第一光模块接收第二数据的时间，第八时间为主设备记录的第一光模块输出第二数据的时间。计算第四差值与第三差值之差得到第二单向延时。
在一种可能的实现方式中，计算模块，具体用于根据[(t2-t1)-(t4-t3)-Δlatency]÷2计算从设备与主设备之间的时间偏差。其中，t1为第一发送时间，t2为第一接收时间，t3为第二发送时间，t4为第二接收时间，Δlatency为双向延时差。
第五方面提供了一种从设备，该从设备包括一个或多个处理器以及存储器，其中，一个或多个处理器用于读取存储在存储器中的软件代码并执行如上述第一方面或第一方面的任一种可能实现方式中的方法。
第六方面提供了一种计算机可读存储介质，该计算机可读存储介质中存储有指令，当其在计算机或处理器上运行时，使得计算机或处理器执行上述第一方面或第一方面的任一种可能实现方式中的方法。
第七方面提供了一种包含指令的计算机程序产品，当其在计算机或处理器上运行时，使得计算机或处理器执行上述第一方面或第一方面的任一种可能实现方式中的方法。
附图说明
图1所示的为1588协议实现时间同步的处理过程的流程图；
图2所示的为本申请实施例提供的主设备向从设备发送数据的示意图；
图3所示的为本申请实施例提供的从设备向主设备发送数据的示意图；
图4所示的为本申请实施例提供的主设备向从设备发送同步报文的示意图；
图5所示的为本申请实施例提供的主设备向从设备发送跟随报文的示意图；
图6所示的为本申请实施例提供的从设备向主设备发送延迟请求报文的示意图；
图7所示的为本申请实施例提供的主设备向从设备发送延迟请求响应报文的示意图；
图8所示的为本申请实施例提供的一种时间同步方法的流程图；
图9所示的为图8中的步骤S11的细化流程图；
图10所示的为图8中的步骤S12的细化流程图；
图11所示的为图8中的步骤S11的细化流程图；
图12所示的为本申请实施例提供的另一种主设备向从设备发送数据的示意图；
图13所示的为图8中的步骤S12的细化流程图；
图14所示的为本申请实施例提供的另一种从设备向主设备发送数据的示意图；
图15所示的为本申请实施例提供的一种从设备的示意图；
图16所示的为本申请实施例提供的另一种从设备的示意图；
图17所示的为本申请实施例提供的又一种从设备的示意图；
图18所示的为本申请实施例提供的又一种从设备的示意图；
图19所示的为本申请实施例提供的一种系统的示意图。
具体实施方式
结合背景技术和图1可知，由于传统的1588协议认为下行传输延时与上行传输延时是相同的，便无需测量下行传输延时和上行传输延时，也无需计算下行传输延时与上行传输延时之间的差值，所以时间偏差＝[(t2-t1)-(t4-t3)]÷2。然而，在某些情况下，下行传输延时与上行传输延时可能并不相同，所以利用传统的1588协议测量出的时间偏差可能会出现误差，从而无法保证从设备的本地时间与主设备的本地时间保持同步。
本申请实施例提供一种时间同步方法，可以解决背景技术中存在的问题，以更加精准的方式测量从设备与主设备的时间偏差，从而保证从设备的本地时间与主设备的本地时间保持同步。本申请实施例提供的时间同步方法可以应用于具有网络处理器和光模块的设备上，例如，具有网络处理器和光模块的设备可以为交换机、路由器或基站等。
下面结合一个具体的应用场景来说明本申请实施例提供的时间同步方法。请结合图2至图7所示，图2所示的为本申请实施例提供的主设备向从设备发送数据的示意图，图3所示的为本申请实施例提供的从设备向主设备发送数据的示意图，图4所示的为本申请实施例提供的主设备向从设备发送同步报文的示意图，图5所示的为本申请实施例提供的主设备向从设备发送跟随报文的示意图，图6所示的为本申请实施例提供的从设备向主设备发送延迟请求报文的示意图，图7所示的为本申请实施例提供的主设备向从设备发送延迟请求响应报文的示意图。
在图2至图7所示的实施例中，图2和图3所示的实施例介绍了从设备2如何得到双向延时差Δlatency，图4至图7所示的实施例介绍了从设备2如何得到(t2-t1)-(t4-t3)。在从设备2得到了双向延时差Δlatency和(t2-t1)-(t4-t3)以后，从设备2便可以根据公式[(t2-t1)-(t4-t3)-Δlatency]÷2来计算时间偏差，从设备2可以利用该时间偏差调整从设备2的第二网络处理器21的本地时间，从而保证从设备2的第二网络处理器21与主设备1的第一网络处理器11保持时间同步。
在图2和图3所示的实施例中，下行传输延时包括五个部分，第一部分为第一网络处理器11与第一光模块12之间的光纤传输延时，第二部分为第一光模块12的发送延时，第三部分为第一光模块12与第二光模块22之间的光纤传输延时，第四部分为第二光模块22的接收延时，第五部分为第二光模块22与第二网络处理器21之间的光纤传输延时。上行传输延时包括五个部分，第一部分为第二网络处理器21与第2光模块22之间的光纤传输延时，第二部分为第二光模块22的发送延时，第三部分为第二光模块22与第一光模块12之间的光纤传输延时，第四部分为第一光模块12的接收延时，第五部分为第一光模块12与第一网络处理器11之间的光纤传输延时。
在图2和图3所示的实施例中，下行传输延时中的光纤传输延时与上行传输延时中的光纤传输延时相同，所以下行传输延时-上行传输延时＝(第一光模块12的发送延时+第二光模块22的接收延时)-(第二光模块22的发送延时+第一光模块12的接收延时)。而且，第一单向延时＝第一光模块12的发送延时+第二光模块22的接收延时，第二单向延时＝第二光模块22的发送延时+第一光模块12的接收延时，所以下行传输延时-上行传输延时＝第一单向延时-第二单向延时＝双向延时差Δlatency。综上，图2和图3所示的实施例介绍了从设备2如何得到双向延时差Δlatency。
在图2至图7所示的实施例中，主设备1包括第一网络处理器11和第一光模块12，从设 备2包括第二网络处理器21和第二光模块22。
下面结合图2所示的实施例介绍从设备2得到第一单向延时的执行过程。
在图2所示的实施例中，主设备1的第一网络处理器11将第一数据发送给第一光模块12，主设备1利用计时器记录第一光模块12接收第一数据的第一时间T1；主设备1的第一光模块12将第一数据转换为第二数据，主设备1的第一光模块12将第二数据发送给从设备2的第二光模块22，主设备1利用计时器记录第一光模块12输出第二数据的第二时间T2，主设备1计算第一时间T1与第二时间T2之差得到第一差值(T1-T2)，主设备1将第一差值(T1-T2)发送给从设备2。
在图2所示的实施例中，从设备2接收主设备1发送的第一差值(T1-T2)。从设备2利用计时器记录第二光模块22接收第二数据的第三时间T3，从设备2的第二光模块22将第二数据转换为第一数据，从设备2的第二光模块22将第一数据发送给第二网络处理器21，从设备2利用计时器记录第二光模块22输出第一数据的第四时间T4。从设备2计算第四时间T4与第三时间T3之差得到第二差值(T4-T3)，从设备2计算第二差值(T4-T3)与第一差值(T1-T2)之差得到第一单向延时Td。
在图2所示的实施例中，由于主设备1的第一光模块12的发送延时＝(T2-T1)，从设备2的第二光模块22的接收延时＝(T4-T3)，第一光模块12的发送延时+第二光模块22的接收延时＝(T4-T3)+(T2-T1)＝(T4-T3)-(T1-T2)＝第一单向延时Td，所以第一单向延时Td可以指示主设备1的第一光模块12的发送延时与从设备2的第二光模块22的接收延时之和。
下面结合图3所示的实施例介绍从设备2得到第二单向延时的执行过程。
在图3所示的实施例中，从设备2的第二网络处理器21将第三数据发送给第二光模块22，从设备2利用计时器记录第二光模块22接收第三数据的第五时间T5；从设备2的第二光模块22将第三数据转换为第四数据，从设备2的第二光模块22将第四数据发送给主设备1的第一光模块12，从设备2利用计时器记录第二光模块22输出第四数据的第六时间T6，从设备2计算第五时间T5与第六时间T6之差得到第三差值(T5-T6)。
在图3所示的实施例中，主设备1利用计时器记录第一光模块12接收第四数据的第七时间T7，主设备1的第一光模块12将第四数据转换为第三数据，主设备1的第一光模块12将第三数据发送给第一网络处理器11，主设备1利用计时器记录第一光模块12输出第三数据的第八时间T8。主设备1计算第八时间T8与第七时间T7之差得到第四差值(T8-T7)，主设备1将第四差值(T8-T7)发送给从设备2。从设备2计算第四差值(T8-T7)与第三差值(T5-T6)之差得到第二单向延时Tu。
在图3所示的实施例中，由于从设备2的第二光模块22的发送延时＝(T6-T5)，主设备1的第一光模块12的接收延时＝(T8-T7)，第二光模块22的发送延时+第一光模块12的接收延时＝(T8-T7)+(T6-T5)＝(T8-T7)-(T5-T6)＝第二单向延时Tu，所以第二单向延时Tu可以指示第二光模块22的发送延时与第一光模块12的接收延时之和。
在图2和图3所示的实施例中，在从设备2得到了第一单向延时Td和第二单向延时Tu以后，从设备2可以计算第一单向延时Td与第二单向延时Tu之差得到双向延时差Δlatency。
在图2和图3所示的实施例中，第一数据、第二数据、第三数据和第四数据可以为数据帧的帧头，第一数据、第二数据、第三数据和第四数据也可以为数据报文的报文头。
下面结合图4至图7所示的实施例介绍从设备2得到第一发送时间t1、第一接收时间t2、第二发送时间t3和第二接收时间t4的执行过程。
请参见图4所示，主设备1的第一网络处理器11将同步报文发送给第一光模块12，主设备1记录第一网络处理器11发送同步报文的第一发送时间t1。主设备1的第一光模块12将同步报文发送给从设备2的第二光模块22，从设备2的第二光模块22将同步报文发送给从设备2的第二网络处理器21，从设备2记录第二网络处理器21接收同步报文的第一接收时间t2。
请参见图5所示，主设备1的第一网络处理器11将第一发送时间t1封装到跟随报文中，主设备1的第一网络处理器11通过第一光模块12和第二光模块22将携带t1的跟随报文发送给从设备2的第二网络处理器21。
请参见图6所示，从设备2的第二网络处理器21将延迟请求报文发送给第二光模块22，从设备2记录第二网络处理器21发送延迟请求报文的第二发送时间t3。从设备2的第二光模块22将延迟请求报文发送给主设备1的第一光模块12，主设备1的第一光模块12将延迟请求报文发送给主设备1的第一网络处理器11，主设备1记录第一网络处理器11接收延迟请求报文的第二接收时间t4。
请参见图7所示，主设备1的第一网络处理器11将第二接收时间t4封装到延迟请求响应报文中，主设备1的第一网络处理器11通过第一光模块12和第二光模块22将携带t4的延迟请求响应报文发送给从设备2的第二网络处理器21。
在图2至图7所示的实施例中，从设备2计算出双向延时差Δlatency，从设备2还得到了第一发送时间t1、第一接收时间t2、第二发送时间t3和第二接收时间t4，此时，从设备2可以基于公式[(t2-t1)-(t4-t3)-Δlatency]÷2计算出从设备与主设备的时间偏差，从设备2可以利用该时间偏差调整从设备2的第二网络处理器21的本地时间，从而保证从设备2的第二网络处理器21与主设备1的第一网络处理器11保持时间同步。由于从设备2计算出的时间偏差更加准确，所以从设备2的第二网络处理器21与主设备1的第一网络处理器11可以在更高的精度上保持时间同步。
需要说明的是，图2至图7所示的实施例用于使读者快速理解本申请实施例的技术原理，并不用于限定本申请实施例的保护范围。图2至图7所示的实施例中提到的具体参数值可以根据本申请实施例的原理进行变化，本申请实施例的保护范围并不限于已经提到的具体参数值。
上文通过图2至图7所示的实施例简要的介绍了本申请实施例提供的应用场景，下面介绍本申请实施例提供的时间同步方法的执行过程、技术原理和实施例。
请参见图8所示，图8所示的为本申请实施例提供的一种时间同步方法的流程图。图8所示的方法可以应用于从设备，该方法可以保证从设备需要与主设备保持时间同步。其中，主设备包括第一光模块和第一网络处理器，从设备包括第二光模块和第二网络处理器。图8所示的方法包括以下步骤。
步骤S11、从设备计算第一单向延时。
其中，第一单向延时用于指示第一光模块的发送延时与第二光模块的接收延时之和。
为了更好的理解步骤S11的具体执行过程，可以结合图2所示的实施例，图2所示的实施例介绍了从设备2计算第一单向延时的执行过程。
步骤S12、从设备计算第二单向延时。
其中，第二单向延时用于指示第二光模块的发送延时与第一光模块的接收延时之和。
为了更好的理解步骤S12的具体执行过程，可以结合图3所示的实施例，图3所示的实施例介绍了从设备2计算第二单向延时的执行过程。
步骤S13、从设备计算第一单向延时与第二单向延时之差得到双向延时差。
步骤S14、从设备根据双向延时差、第一发送时间、第一接收时间、第二发送时间和第二接收时间计算从设备与主设备之间的时间偏差。
其中，第一发送时间为主设备记录的第一网络处理器发送同步报文的时间，第一接收时间为从设备记录的第二网络处理器接收同步报文的时间，第二发送时间为从设备记录的第二网络处理器发送延时请求报文的时间，第二接收时间为主设备记录的第一网络处理器接收延时请求报文的时间。
为了更好的理解步骤S14的具体执行过程，可以结合图4至图7所示的实施例，图4至图7所示的实施例介绍了从设备2得到第一发送时间t1、第一接收时间t2、第二发送时间t3和第二接收时间t4的执行过程。
在从设备得到双向延时差、第一发送时间、第一接收时间、第二发送时间和第二接收时间以后，从设备可以基于公式[(t2-t1)-(t4-t3)-Δlatency]÷2计算出从设备与主设备的时间偏差。其中，t1为第一发送时间，t2为第一接收时间，t3为第二发送时间，t4为第二接收时间，Δlatency为双向延时差。
在步骤S14中，在计算从设备与主设备之间的时间偏差时，双向延时差用于指示第一单向延时与第二单向延时的差值，从而可以保证最终计算得到的时间偏差更加准确。
步骤S15、从设备利用时间偏差调整从设备的本地时间。
在图8所示的实施例中，本申请实施例在计算时间偏差的过程中，考虑到第一单向延时与第二单向延时并不相同的情况，从设备需要测量双向延时差，并根据双向延时差、第一发送时间、第一接收时间、第二发送时间和第二接收时间计算从设备与主设备之间的时间偏差，从设备利用时间偏差调整从设备的本地时间。本申请实施例以更加精准的方式测量从设备与主设备的时间偏差，可以保证从设备的本地时间与主设备的本地时间保持同步。
请参见图9所示，图9所示的为图8中的步骤S11的细化流程图。图9所示的方法包括以下步骤。
步骤S21、从设备接收主设备发送的第一差值。
其中，第一差值为第一时间与第二时间之间的差值，第一时间为主设备记录的第一光模块接收第一数据的时间，第二时间为主设备记录的第一光模块输出第二数据的时间。
步骤S22、从设备记录第二光模块接收第二数据的第三时间。
步骤S23、从设备记录第二光模块输出第一数据的第四时间。
步骤S24、从设备计算第四时间与第三时间之差得到第二差值。
步骤S25、从设备计算第二差值与第一差值之差得到第一单向延时。
其中，为了更好的理解步骤S21至步骤S25的具体执行过程，可以结合图2所示的实施例，图2所示的实施例介绍了从设备2计算第一单向延时的执行过程。
在图9所示的实施例中，主设备将第一差值发送给从设备，以便于从设备在计算出第二差值以后，从设备可以计算第二差值与第一差值之差得到第一单向延时。
当然，第一单项延时可以由主设备来计算，那么便需要从设备将第二差值发送给主设 备，以便于主设备在计算出第一差值以后，主设备可以计算第二差值与第一差值之差得到第一单向延时，主设备再将第一单项延时发送给从设备。
请参见图10所示，图10所示的为图8中的步骤S12的细化流程图。图10所示的方法包括以下步骤。
步骤S31、从设备记录第二光模块接收第三数据的第五时间。
步骤S32、从设备记录第二光模块输出第四数据的第六时间。
步骤S33、从设备计算第五时间与第六时间之差得到第三差值。
步骤S34、从设备接收主设备发送的第四差值。
其中，第四差值为第八时间与第七时间之间的差值，第七时间为主设备记录的第一光模块接收第四数据的时间，第八时间为主设备记录的第一光模块输出第三数据的时间。
步骤S35、从设备计算第四差值与第三差值之差得到第二单向延时。
其中，为了更好的理解步骤S31至步骤S35的具体执行过程，可以结合图3所示的实施例，图3所示的实施例介绍了从设备2计算第二单向延时的执行过程。
在图10所示的实施例中，主设备将第四差值发送给从设备，以便于从设备在计算出第三差值以后，从设备可以计算第四差值与第三差值之差得到第二单向延时。
当然，第二单项延时可以由主设备来计算，那么便需要从设备将第三差值发送给主设备，以便于主设备在计算出第四差值以后，主设备可以计算第四差值与第三差值之差得到第二单向延时，主设备再将第二单项延时发送给从设备。
请参见图11所示，图11所示的为图8中的步骤S11的细化流程图。图11所示的方法包括以下步骤。
步骤S41、从设备接收主设备发送的第一差值。
其中，第一差值为第一时间与第二时间之间的差值，第一时间为主设备记录的第一光模块接收第一数据的时间，第二时间为主设备记录的第一光模块输出第一数据的时间。
步骤S42、从设备记录第二光模块接收第一数据的第三时间。
步骤S43、从设备记录第二光模块输出第一数据的第四时间。
步骤S44、从设备计算第四时间与第三时间之差得到第二差值。
步骤S45、从设备计算第二差值与第一差值之差得到第一单向延时。
在图11所示的实施例中，主设备将第一差值发送给从设备，以便于从设备在计算出第二差值以后，从设备可以计算第二差值与第一差值之差得到第一单向延时。
当然，第一单项延时可以由主设备来计算，那么便需要从设备将第二差值发送给主设备，以便于主设备在计算出第一差值以后，主设备可以计算第二差值与第一差值之差得到第一单向延时，主设备再将第一单项延时发送给从设备。
为了更好的理解步骤S41至步骤S45的具体执行过程，可以结合图12所示的实施例，图12所示的实施例介绍了从设备2计算第一单向延时的执行过程。
请参见图12所示，图12所示的为本申请实施例提供的另一种主设备向从设备发送数据的示意图。在图12所示的实施例中，主设备1的第一网络处理器11将第一数据发送给第一光模块12，主设备1利用计时器记录第一光模块12接收第一数据的第一时间T1；主设备1的第一光模块12将第一数据发送给从设备2的第二光模块22，主设备1利用计时器记录第一光模块12输出第一数据的第二时间T2，主设备1计算第一时间T1与第二时间T2之差得到第一 差值(T1-T2)，主设备1将第一差值(T1-T2)发送给从设备2。
在图12所示的实施例中，从设备2接收主设备1发送的第一差值(T1-T2)。从设备2利用计时器记录第二光模块22接收第一数据的第三时间T3，从设备2的第二光模块22将第一数据发送给第二网络处理器21，从设备2利用计时器记录第二光模块22输出第一数据的第四时间T4。从设备2计算第四时间T4与第三时间T3之差得到第二差值(T4-T3)，从设备2计算第二差值(T4-T3)与第一差值(T1-T2)之差得到第一单向延时Td。
在图12所示的实施例中，由于主设备1的第一光模块12的发送延时＝(T2-T1)，从设备2的第二光模块22的接收延时＝(T4-T3)，第一光模块12的发送延时+第二光模块22的接收延时＝(T4-T3)+(T2-T1)＝(T4-T3)-(T1-T2)＝第一单向延时Td，所以第一单向延时Td可以指示主设备1的第一光模块12的发送延时与从设备2的第二光模块22的接收延时之和。
在图12所示的实施例中，第一数据可以为数据帧的帧头，第一数据也可以为数据报文的报文头。
请参见图13所示，图13所示的为图8中的步骤S12的细化流程图。图13所示的方法包括以下步骤。
步骤S51、从设备记录第二光模块接收第二数据的第五时间。
步骤S52、从设备记录第二光模块输出第二数据的第六时间。
步骤S53、从设备计算第五时间与第六时间之差得到第三差值。
步骤S54、从设备接收主设备发送的第四差值。
其中，第四差值为第八时间与第七时间之间的差值，第七时间为主设备记录的第一光模块接收第二数据的时间，第八时间为主设备记录的第一光模块输出第二数据的时间。
步骤S55、从设备计算第四差值与第三差值之差得到第二单向延时。
在图13所示的实施例中，主设备将第四差值发送给从设备，以便于从设备在计算出第三差值以后，从设备可以计算第四差值与第三差值之差得到第二单向延时。
当然，第二单项延时可以由主设备来计算，那么便需要从设备将第三差值发送给主设备，以便于主设备在计算出第四差值以后，主设备可以计算第四差值与第三差值之差得到第二单向延时，主设备再将第二单项延时发送给从设备。
为了更好的理解步骤S51至步骤S55的具体执行过程，可以结合图14所示的实施例，图14所示的实施例介绍了从设备2计算第二单向延时的执行过程。
请参见图14所示，图14所示的为本申请实施例提供的另一种从设备向主设备发送数据的示意图。在图14所示的实施例中，从设备2的第二网络处理器21将第二数据发送给第二光模块22，从设备2利用计时器记录第二光模块22接收第二数据的第五时间T5；从设备2的第二光模块22将第二数据发送给主设备1的第一光模块12，从设备2利用计时器记录第二光模块22输出第二数据的第六时间T6，从设备2计算第五时间T5与第六时间T6之差得到第三差值(T5-T6)。
在图14所示的实施例中，主设备1利用计时器记录第一光模块12接收第二数据的第七时间T7，主设备1的第一光模块12将第二数据发送给第一网络处理器11，主设备1利用计时器记录第一光模块12输出第二数据的第八时间T8。主设备1计算第八时间T8与第七时间T7之差得到第四差值(T8-T7)，主设备1将第四差值(T8-T7)发送给从设备2。从设备2计 算第四差值(T8-T7)与第三差值(T5-T6)之差得到第二单向延时Tu。
在图14所示的实施例中，由于从设备2的第二光模块22的发送延时＝(T6-T5)，主设备1的第一光模块12的接收延时＝(T8-T7)，第二光模块22的发送延时+第一光模块12的接收延时＝(T8-T7)+(T6-T5)＝(T8-T7)-(T5-T6)＝第二单向延时Tu，所以第二单向延时Tu可以指示第二光模块22的发送延时与第一光模块12的接收延时之和。
在图14所示的实施例中，第二数据可以为数据帧的帧头，第二数据也可以为数据报文的报文头。
请参见图15所示，图15所示的为本申请实施例提供的一种从设备的示意图。图15所示的从设备需要与主设备保持时间同步。其中，主设备包括第一光模块和第一网络处理器，从设备包括第二光模块和第二网络处理器。该从设备还包括以下模块：
计算模块31，用于从设备计算第一单向延时，第一单向延时用于指示第一光模块的发送延时与第二光模块的接收延时之和；计算第二单向延时，第二单向延时用于指示第二光模块的发送延时与第一光模块的接收延时之和；计算第一单向延时与第二单向延时之差得到双向延时差；根据双向延时差、第一发送时间、第一接收时间、第二发送时间和第二接收时间计算从设备与主设备之间的时间偏差；其中，第一发送时间为主设备记录的第一网络处理器发送同步报文的时间，第一接收时间为从设备记录的第二网络处理器接收同步报文的时间，第二发送时间为从设备记录的第二网络处理器发送延时请求报文的时间，第二接收时间为主设备记录的第一网络处理器接收延时请求报文的时间。关于计算模块31的实现方式，请参考上述图8所示的方法实施例中步骤S11至步骤S14的详细描述。
调整模块32，用于利用时间偏差调整从设备的本地时间。关于调整模块32的实现方式，请参考上述图8所示的方法实施例中步骤S15的详细描述。
在一种可实现的实施例中，计算模块31，具体用于接收主设备发送的第一差值，第一差值为第一时间与第二时间之间的差值，第一时间为主设备记录的第一光模块接收第一数据的时间，第二时间为主设备记录的第一光模块输出第二数据的时间；记录第二光模块接收第二数据的第三时间；记录第二光模块输出第一数据的第四时间；计算第四时间与第三时间之差得到第二差值；计算第二差值与第一差值之差得到第一单向延时。关于计算模块31的实现方式，请参考上述图9所示的方法实施例中步骤S21至步骤S25的详细描述。
在一种可实现的实施例中，计算模块31，具体用于记录第二光模块接收第三数据的第五时间；记录第二光模块输出第四数据的第六时间；计算第五时间与第六时间之差得到第三差值；接收主设备发送的第四差值，第四差值为第八时间与第七时间之间的差值，第七时间为主设备记录的第一光模块接收第四数据的时间，第八时间为主设备记录的第一光模块输出第三数据的时间；计算第四差值与第三差值之差得到第二单向延时。关于计算模块31的实现方式，请参考上述图10所示的方法实施例中步骤S31至步骤S35的详细描述。
在一种可实现的实施例中，计算模块31，具体用于接收主设备发送的第一差值，第一差值为第一时间与第二时间之间的差值，第一时间为主设备记录的第一光模块接收第一数据的时间，第二时间为主设备记录的第一光模块输出第一数据的时间；记录第二光模块接收第一数据的第三时间；记录第二光模块输出第一数据的第四时间；计算第四时间与第三时间之差得到第二差值；计算第二差值与第一差值之差得到第一单向延时。关于计算模块31的实现方式，请参考上述图11所示的方法实施例中步骤S41至步骤S45的详细描述。
在一种可实现的实施例中，计算模块31，具体用于记录第二光模块接收第二数据的第五时间；记录第二光模块输出第二数据的第六时间；计算第五时间与第六时间之差得到第三差值；接收主设备发送的第四差值，第四差值为第八时间与第七时间之间的差值，第七时间为主设备记录的第一光模块接收第二数据的时间，第八时间为主设备记录的第一光模块输出第二数据的时间；计算第四差值与第三差值之差得到第二单向延时。关于计算模块31的实现方式，请参考上述图13所示的方法实施例中步骤S51至步骤S55的详细描述。
在一种可实现的实施例中，计算模块31，具体用于根据[(t2-t1)-(t4-t3)-Δlatency]÷2计算从设备与主设备之间的时间偏差；其中，t1为第一发送时间，t2为第一接收时间，t3为第二发送时间，t4为第二接收时间，Δlatency为双向延时差。关于计算模块31的实现方式，请参考上述图8所示的方法实施例中步骤S14的详细描述。
请参见图16所示，图16所示的为本申请实施例提供的另一种从设备的示意图。图16所示的从设备40需要与主设备50保持时间同步。其中，主设备50包括第一光模块51和第一网络处理器52，从设备40包括第二光模块41、第二网络处理器42和测量模块43，第二光模块41分别与第二网络处理器42和测量模块43连接。
在图16所示的实施例中，测量模块43，用于计算第一单向延时，第一单向延时用于指示第一光模块51的发送延时与第二光模块41的接收延时之和；还用于计算第二单向延时，第二单向延时用于指示第二光模块41的发送延时与第一光模块51的接收延时之和；还用于计算第一单向延时与第二单向延时之差得到双向延时差；还用于根据双向延时差、第一发送时间、第一接收时间、第二发送时间和第二接收时间计算从设备40与主设备50之间的时间偏差；其中，第一发送时间为主设备50记录的第一网络处理器52发送同步报文的时间，第一接收时间为从设备40记录的第二网络处理器42接收同步报文的时间，第二发送时间为从设备40记录的第二网络处理器42发送延时请求报文的时间，第二接收时间为主设备50记录的第一网络处理器52接收延时请求报文的时间。第二网络处理器42，用于利用时间偏差调整从设备40的本地时间。
在一种可实现的实施例中，测量模块43，具体用于接收主设备50发送的第一差值，第一差值为第一时间与第二时间之间的差值，第一时间为主设备50记录的第一光模块51接收第一数据的时间，第二时间为主设备50记录的第一光模块51输出第二数据的时间；记录第二光模块41接收第二数据的第三时间；记录第二光模块41输出第一数据的第四时间；计算第四时间与第三时间之差得到第二差值；计算第二差值与第一差值之差得到第一单向延时。
在一种可实现的实施例中，测量模块43，具体用于记录第二光模块41接收第三数据的第五时间；记录第二光模块41输出第四数据的第六时间；计算第五时间与第六时间之差得到第三差值；接收主设备50发送的第四差值，第四差值为第八时间与第七时间之间的差值，第七时间为主设备50记录的第一光模块51接收第四数据的时间，第八时间为主设备50记录的第一光模块51输出第三数据的时间；计算第四差值与第三差值之差得到第二单向延时。
在一种可实现的实施例中，测量模块43，具体用于接收主设备50发送的第一差值，第一差值为第一时间与第二时间之间的差值，第一时间为主设备50记录的第一光模块51接收第一数据的时间，第二时间为主设备50记录的第一光模块51输出第一数据的时间；记录第二光模块41接收第一数据的第三时间；记录第二光模块41输出第一数据的第四时间；计算第四时间与第三时间之差得到第二差值；计算第二差值与第一差值之差得到第一单向延时。
在一种可实现的实施例中，测量模块43，具体用于记录第二光模块41接收第二数据的第五时间；记录第二光模块41输出第二数据的第六时间；计算第五时间与第六时间之差得到第三差值；接收主设备50发送的第四差值，第四差值为第八时间与第七时间之间的差值，第七时间为主设备50记录的第一光模块51接收第二数据的时间，第八时间为主设备50记录的第一光模块51输出第二数据的时间；计算第四差值与第三差值之差得到第二单向延时。
在一种可实现的实施例中，测量模块43，具体用于根据[(t2-t1)-(t4-t3)-Δlatency]÷2计算从设备40与主设备50之间的时间偏差；其中，t1为第一发送时间，t2为第一接收时间，t3为第二发送时间，t4为第二接收时间，Δlatency为双向延时差。
请参见图17所示，图17所示的为本申请实施例提供的又一种从设备的示意图。图17所示的从设备60需要与主设备70保持时间同步。其中，主设备70包括第一光模块71和第一网络处理器72，从设备60包括第二光模块61和第二网络处理器62，第二光模块61包括测量模块63，第二光模块61与第二网络处理器62相互连接。
在图16和图17中，图16中所示的测量模块43设置在第二光模块41的外部，图17中所示的测量模块63设置在第二光模块61的内部，图16中所示的测量模块43与图17中所示的测量模块63实现的功能相同，关于图17中所示的测量模块63的具体实现，可以参见图16中所示的测量模块43的相关说明。
请参见图18所示，图18所示的为本申请实施例提供的又一种从设备的示意图。图18所示的从设备80包括网络处理器81和光模块82，光模块82包括串行解串器821、客户端进程822、数字信号处理进程823、数模转换器824和测量模块825。
下面介绍测量模块825计算光模块82的发送延时的过程。
首先，在串行解串器821接收到网络处理器81发送的客户业务数据时，串行解串器821会将客户业务数据分别发送给客户端进程822和测量模块825。在测量模块825接收到串行解串器821发送的客户业务数据时，在测量模块825会记录下第一时间T1，第一时间T1用于指示客户业务数据进入光模块82的时间。
然后，在客户端进程822接收到串行解串器821发送的客户业务数据以后，客户端进程822会将客户业务数据转换为光传输数据，再将光传输数据发送给数字信号处理进程823。
其次，在数字信号处理进程823接收到客户端进程822发送的光传输数据以后，数字信号处理进程823会将光传输数据转换为基带信号，再将基带信号发送给数模转换器824。
再次，在数模转换器824接收到数字信号处理进程823发送的基带信号以后，数模转换器824会将基带信号转换为模拟信号，再将模拟信号分别发送给主设备200和测量模块825。在测量模块825接收到数模转换器824发送的模拟信号时，在测量模块825会记录下第二时间T2，第二时间T2用于指示模拟信号离开光模块82的时间。
最后，测量模块825得到了客户业务数据进入光模块82的第一时间T1和模拟信号离开光模块82的第二时间T2，测量模块825计算第二时间T2与第一时间T1的差值得到光模块82的发送延时。
关于测量模块825计算光模块82的接收延时的过程，与测量模块825计算光模块82的发送延时的原理相同，同样需要测量模块825分别记录数据进入光模块82的时间和数据离开光模块82的时间，并计算数据离开光模块82的时间与数据进入光模块82的时间的差值得到光模块82的接收延时。
当然，图18所示的从设备82的结构仅是一种具体的实现方式，从设备82还可以为其他类型的结构，从设备82的结构并不局限于图18所示的实施例。
另外，图18所示的测量模块825设置在光模块82的内部，测量模块825还可以设置在光模块82的外部。
请参见图19所示，图19所示的为本申请实施例提供的一种系统的示意图。图19所示的系统包括主设备90和从设备100，从设备100需要与主设备90保持时间同步，其中，主设备90包括第一光模块91和第一网络处理器92，从设备100包括第二光模块101、第二网络处理器102和测量模块103。
在图19所示的实施例中，测量模块103，用于计算第一单向延时，第一单向延时用于指示第一光模块91的发送延时与第二光模块101的接收延时之和；还用于计算第二单向延时，第二单向延时用于指示第二光模块101的发送延时与第一光模块91的接收延时之和；还用于计算第一单向延时与第二单向延时之差得到双向延时差；还用于根据双向延时差、第一发送时间、第一接收时间、第二发送时间和第二接收时间计算从设备100与主设备90之间的时间偏差；其中，第一发送时间为主设备90记录的第一网络处理器92发送同步报文的时间，第一接收时间为从设备100记录的第二网络处理器102接收同步报文的时间，第二发送时间为从设备100记录的第二网络处理器102发送延时请求报文的时间，第二接收时间为主设备90记录的第一网络处理器92接收延时请求报文的时间。第二网络处理器102，用于利用时间偏差调整从设备100的本地时间。
在一种可实现的实施例中，测量模块103，具体用于接收主设备90发送的第一差值，第一差值为第一时间与第二时间之间的差值，第一时间为主设备90记录的第一光模块91接收第一数据的时间，第二时间为主设备90记录的第一光模块91输出第二数据的时间；记录第二光模块101接收第二数据的第三时间；记录第二光模块101输出第一数据的第四时间；计算第四时间与第三时间之差得到第二差值；计算第二差值与第一差值之差得到第一单向延时。
在一种可实现的实施例中，测量模块103，具体用于记录第二光模块101接收第三数据的第五时间；记录第二光模块101输出第四数据的第六时间；计算第五时间与第六时间之差得到第三差值；接收主设备90发送的第四差值，第四差值为第八时间与第七时间之间的差值，第七时间为主设备90记录的第一光模块91接收第四数据的时间，第八时间为主设备90记录的第一光模块91输出第三数据的时间；计算第四差值与第三差值之差得到第二单向延时。
在一种可实现的实施例中，测量模块103，具体用于接收主设备90发送的第一差值，第一差值为第一时间与第二时间之间的差值，第一时间为主设备90记录的第一光模块91接收第一数据的时间，第二时间为主设备90记录的第一光模块91输出第一数据的时间；记录第二光模块101接收第一数据的第三时间；记录第二光模块101输出第一数据的第四时间；计算第四时间与第三时间之差得到第二差值；计算第二差值与第一差值之差得到第一单向延时。
在一种可实现的实施例中，测量模块103，具体用于记录第二光模块101接收第二数据的第五时间；记录第二光模块101输出第二数据的第六时间；计算第五时间与第六时间之差得到第三差值；接收主设备90发送的第四差值，第四差值为第八时间与第七时间之间的 差值，第七时间为主设备90记录的第一光模块91接收第二数据的时间，第八时间为主设备90记录的第一光模块91输出第二数据的时间；计算第四差值与第三差值之差得到第二单向延时。
在一种可实现的实施例中，第二网络处理器102与第二光模块101相互连接，第二光模块101包括测量模块103；或者，第二网络处理器102、第二光模块101和测量模块103依次连接。
在一种可实现的实施例中，测量模块103，具体用于根据[(t2-t1)-(t4-t3)-Δlatency]÷2计算从设备100与主设备90之间的时间偏差；其中，t1为第一发送时间，t2为第一接收时间，t3为第二发送时间，t4为第二接收时间，Δlatency为双向延时差。
需要说明的是，当上述实施例中涉及软件实现的功能时，相关软件或软件中的模块可存储在计算机可读介质中或作为计算机可读介质上的一个或多个指令或代码进行传输。计算机可读介质包括计算机存储介质和通信介质，其中通信介质包括便于从一个地方向另一个地方传送计算机程序的任何介质。存储介质可以是计算机能够存取的任何可用介质。以此为例但不限于：计算机可读介质可以包括RAM、ROM、EEPROM、CD-ROM或其他光盘存储、磁盘存储介质或者其他磁存储设备、或者能够用于携带或存储具有指令或数据结构形式的期望的程序代码并能够由计算机存取的任何其他介质。此外。任何连接可以适当的成为计算机可读介质。例如，如果软件是使用同轴电缆、光纤光缆、双绞线、数字用户线(DSL)或者诸如红外线、无线电和微波之类的无线技术从网站、服务器或者其他远程源传输的，那么同轴电缆、光纤光缆、双绞线、DSL或者诸如红外线、无线和微波之类的无线技术包括在所属介质的定影中。如本申请所使用的，盘(Disk)和碟(disc)包括压缩光碟(CD)、激光碟、光碟、数字通用光碟(DVD)、软盘和蓝光光碟，其中盘通常磁性的复制数据，而碟则用激光来光学的复制数据。上面的组合也应当包括在计算机可读介质的保护范围之内。
此外，以上实施例仅用以说明本申请的技术方案而非对其限制；尽管参照前述实施例对本申请进行了详细的说明，然而本领域的普通技术人员应当理解：其依然可对前述各实施例所记载的技术方案进行修改，或对其中部分技术特征进行等同替换。

Claims (20)

  1. 一种时间同步方法，其特征在于，所述方法应用于从设备，所述从设备与主设备保持时间同步，所述主设备包括第一光模块和第一网络处理器，所述从设备包括第二光模块和第二网络处理器，所述方法包括：
    所述从设备计算第一单向延时，所述第一单向延时用于指示所述第一光模块的发送延时与所述第二光模块的接收延时之和；
    所述从设备计算第二单向延时，所述第二单向延时用于指示所述第二光模块的发送延时与所述第一光模块的接收延时之和；
    所述从设备计算所述第一单向延时与所述第二单向延时之差得到双向延时差；
    所述从设备根据所述双向延时差、第一发送时间、第一接收时间、第二发送时间和第二接收时间计算所述从设备与所述主设备之间的时间偏差；其中，所述第一发送时间为所述主设备记录的第一网络处理器发送同步报文的时间，所述第一接收时间为所述从设备记录的第二网络处理器接收所述同步报文的时间，所述第二发送时间为所述从设备记录的所述第二网络处理器发送延时请求报文的时间，所述第二接收时间为所述主设备记录的所述第一网络处理器接收所述延时请求报文的时间；
    所述从设备利用所述时间偏差调整所述从设备的本地时间。
  2. 根据权利要求1所述的时间同步方法，其特征在于，所述从设备计算第一单向延时包括：
    所述从设备接收所述主设备发送的第一差值，所述第一差值为第一时间与第二时间之间的差值，所述第一时间为所述主设备记录的所述第一光模块接收第一数据的时间，所述第二时间为所述主设备记录的所述第一光模块输出第二数据的时间；
    所述从设备记录所述第二光模块接收所述第二数据的第三时间；
    所述从设备记录所述第二光模块输出所述第一数据的第四时间；
    所述从设备计算所述第四时间与所述第三时间之差得到第二差值；
    所述从设备计算所述第二差值与所述第一差值之差得到第一单向延时。
  3. 根据权利要求1或2所述的时间同步方法，其特征在于，所述从设备计算第二单向延时包括：
    所述从设备记录所述第二光模块接收第三数据的第五时间；
    所述从设备记录所述第二光模块输出第四数据的第六时间；
    所述从设备计算所述第五时间与所述第六时间之差得到第三差值；
    所述从设备接收所述主设备发送的第四差值，所述第四差值为第八时间与第七时间之间的差值，所述第七时间为所述主设备记录的所述第一光模块接收所述第四数据的时间，所述第八时间为所述主设备记录的所述第一光模块输出所述第三数据的时间；
    所述从设备计算所述第四差值与所述第三差值之差得到第二单向延时。
  4. 根据权利要求1所述的时间同步方法，其特征在于，所述从设备计算第一单向延时包括：
    所述从设备接收所述主设备发送的第一差值，所述第一差值为第一时间与第二时间之间的差值，所述第一时间为所述主设备记录的所述第一光模块接收第一数据的时间，所述第二时间为所述主设备记录的所述第一光模块输出所述第一数据的时间；
    所述从设备记录所述第二光模块接收所述第一数据的第三时间；
    所述从设备记录所述第二光模块输出所述第一数据的第四时间；
    所述从设备计算所述第四时间与所述第三时间之差得到第二差值；
    所述从设备计算所述第二差值与所述第一差值之差得到第一单向延时。
  5. 根据权利要求1或4所述的时间同步方法，其特征在于，所述从设备计算第二单向延时包括：
    所述从设备记录所述第二光模块接收第二数据的第五时间；
    所述从设备记录所述第二光模块输出所述第二数据的第六时间；
    所述从设备计算所述第五时间与所述第六时间之差得到第三差值；
    所述从设备接收所述主设备发送的第四差值，所述第四差值为第八时间与第七时间之间的差值，所述第七时间为所述主设备记录的所述第一光模块接收所述第二数据的时间，所述第八时间为所述主设备记录的所述第一光模块输出所述第二数据的时间；
    所述从设备计算所述第四差值与所述第三差值之差得到第二单向延时。
  6. 根据权利要求1至5中任意一项所述的时间同步方法，其特征在于，所述从设备根据所述双向延时差、第一发送时间、第一接收时间、第二发送时间和第二接收时间计算所述从设备与所述主设备之间的时间偏差包括：
    所述从设备根据[(t2-t1)-(t4-t3)-Δlatency]÷2计算所述从设备与所述主设备之间的时间偏差；
    其中，t1为所述第一发送时间，t2为所述第一接收时间，t3为所述第二发送时间，t4为所述第二接收时间，Δlatency为所述双向延时差。
  7. 一种从设备，其特征在于，所述从设备与主设备保持时间同步，所述主设备包括第一网络处理器和第一光模块，所述从设备包括第二网络处理器、第二光模块和测量模块；
    所述测量模块，用于计算第一单向延时，所述第一单向延时用于指示所述第一光模块的发送延时与所述第二光模块的接收延时之和；还用于计算第二单向延时，所述第二单向延时用于指示所述第二光模块的发送延时与所述第一光模块的接收延时之和；还用于计算所述第一单向延时与所述第二单向延时之差得到双向延时差；还用于根据所述双向延时差、第一发送时间、第一接收时间、第二发送时间和第二接收时间计算所述从设备与所述主设备之间的时间偏差；其中，所述第一发送时间为所述主设备记录的第一网络处理器发送同步报文的时间，所述第一接收时间为所述从设备记录的第二网络处理器接收所述同步报文的时间，所述第二发送时间为所述从设备记录的所述第二网络处理器发送延时请求报文的时间，所述第二接收时间为所述主设备记录的所述第一网络处理器接收所述延时请求报文的时间；
    所述第二网络处理器，用于利用所述时间偏差调整所述从设备的本地时间。
  8. 根据权利要求7所述的从设备，其特征在于：
    所述测量模块，具体用于接收所述主设备发送的第一差值，所述第一差值为第一时间与第二时间之间的差值，所述第一时间为所述主设备记录的所述第一光模块接收第一数据的时间，所述第二时间为所述主设备记录的所述第一光模块输出第二数据的时间；记录所述第二光模块接收所述第二数据的第三时间；记录所述第二光模块输出所述第一数据的第四时间；计算所述第四时间与所述第三时间之差得到第二差值；计算所述第二差值与所述第一差值之差得到第一单向延时。
  9. 根据权利要求7或8所述的从设备，其特征在于：
    所述测量模块，具体用于记录所述第二光模块接收第三数据的第五时间；记录所述第二光模块输出第四数据的第六时间；计算所述第五时间与所述第六时间之差得到第三差值；接收所述主设备发送的第四差值，所述第四差值为第八时间与第七时间之间的差值，所述第七时间为所述主设备记录的所述第一光模块接收所述第四数据的时间，所述第八时间为所述主设备记录的所述第一光模块输出所述第三数据的时间；计算所述第四差值与所述第三差值之差得到第二单向延时。
  10. 根据权利要求7所述的从设备，其特征在于：
    所述测量模块，具体用于接收所述主设备发送的第一差值，所述第一差值为第一时间与第二时间之间的差值，所述第一时间为所述主设备记录的所述第一光模块接收第一数据的时间，所述第二时间为所述主设备记录的所述第一光模块输出所述第一数据的时间；记录所述第二光模块接收所述第一数据的第三时间；记录所述第二光模块输出所述第一数据的第四时间；计算所述第四时间与所述第三时间之差得到第二差值；计算所述第二差值与所述第一差值之差得到第一单向延时。
  11. 根据权利要求7或10所述的从设备，其特征在于：
    所述测量模块，具体用于记录所述第二光模块接收第二数据的第五时间；记录所述第二光模块输出所述第二数据的第六时间；计算所述第五时间与所述第六时间之差得到第三差值；接收所述主设备发送的第四差值，所述第四差值为第八时间与第七时间之间的差值，所述第七时间为所述主设备记录的所述第一光模块接收所述第二数据的时间，所述第八时间为所述主设备记录的所述第一光模块输出所述第二数据的时间；计算所述第四差值与所述第三差值之差得到第二单向延时。
  12. 根据权利要求7至11中任意一项所述的从设备，其特征在于：
    所述第二网络处理器与所述第二光模块相互连接，所述第二光模块包括所述测量模块；或者，
    所述第二网络处理器、所述第二光模块和所述测量模块依次连接。
  13. 根据权利要求7至12中任意一项所述的从设备，其特征在于：
    所述测量模块，具体用于根据[(t2-t1)-(t4-t3)-Δlatency]÷2计算所述从设备与所述主设备之间的时间偏差；
    其中，t1为所述第一发送时间，t2为所述第一接收时间，t3为所述第二发送时间，t4为所述第二接收时间，Δlatency为所述双向延时差。
  14. 一种系统，其特征在于，所述系统包括主设备和从设备，所述从设备与所述主设备保持时间同步，所述主设备包括第一光模块和第一网络处理器，所述从设备包括第二光模块、第二网络处理器和测量模块：
    所述测量模块，用于计算第一单向延时，所述第一单向延时用于指示所述第一光模块的发送延时与所述第二光模块的接收延时之和；还用于计算第二单向延时，所述第二单向延时用于指示所述第二光模块的发送延时与所述第一光模块的接收延时之和；还用于计算所述第一单向延时与所述第二单向延时之差得到双向延时差；还用于根据所述双向延时差、第一发送时间、第一接收时间、第二发送时间和第二接收时间计算所述从设备与所述主设备之间的时间偏差；其中，所述第一发送时间为所述主设备记录的第一网络处理器发送同步报文的时间，所述第一接收时间为所述从设备记录的第二网络处理器接收所述同步报文的时间，所述第二发送时间为所述从设备记录的所述第二网络处理器发送延时请求报文的时间，所述第二接收时间为所述主设备记录的所述第一网络处理器接收所述延时请求报文的时间；
    所述第二网络处理器，用于利用所述时间偏差调整所述从设备的本地时间。
  15. 根据权利要求14所述的系统，其特征在于：
    所述测量模块，具体用于接收所述主设备发送的第一差值，所述第一差值为第一时间与第二时间之间的差值，所述第一时间为所述主设备记录的所述第一光模块接收第一数据的时间，所述第二时间为所述主设备记录的所述第一光模块输出第二数据的时间；记录所述第二光模块接收所述第二数据的第三时间；记录所述第二光模块输出所述第一数据的第四时间；计算所述第四时间与所述第三时间之差得到第二差值；计算所述第二差值与所述第一差值之差得到第一单向延时。
  16. 根据权利要求14或15所述的系统，其特征在于：
    所述测量模块，具体用于记录所述第二光模块接收第三数据的第五时间；记录所述第二光模块输出第四数据的第六时间；计算所述第五时间与所述第六时间之差得到第三差值；接收所述主设备发送的第四差值，所述第四差值为第八时间与第七时间之间的差值，所述第七时间为所述主设备记录的所述第一光模块接收所述第四数据的时间，所述第八时间为所述主设备记录的所述第一光模块输出所述第三数据的时间；计算所述第四差值与所述第三差值之差得到第二单向延时。
  17. 根据权利要求14所述的系统，其特征在于：
    所述测量模块，具体用于接收所述主设备发送的第一差值，所述第一差值为第一时间与第二时间之间的差值，所述第一时间为所述主设备记录的所述第一光模块接收第一数据 的时间，所述第二时间为所述主设备记录的所述第一光模块输出所述第一数据的时间；记录所述第二光模块接收所述第一数据的第三时间；记录所述第二光模块输出所述第一数据的第四时间；计算所述第四时间与所述第三时间之差得到第二差值；计算所述第二差值与所述第一差值之差得到第一单向延时。
  18. 根据权利要求14或17所述的系统，其特征在于：
    所述测量模块，具体用于记录所述第二光模块接收第二数据的第五时间；记录所述第二光模块输出所述第二数据的第六时间；计算所述第五时间与所述第六时间之差得到第三差值；接收所述主设备发送的第四差值，所述第四差值为第八时间与第七时间之间的差值，所述第七时间为所述主设备记录的所述第一光模块接收所述第二数据的时间，所述第八时间为所述主设备记录的所述第一光模块输出所述第二数据的时间；计算所述第四差值与所述第三差值之差得到第二单向延时。
  19. 根据权利要求14至18中任意一项所述的系统，其特征在于：
    所述第二网络处理器与所述第二光模块相互连接，所述第二光模块包括所述测量模块；或者，
    所述第二网络处理器、所述第二光模块和所述测量模块依次连接。
  20. 根据权利要求14至19中任意一项所述的系统，其特征在于：
    所述测量模块，具体用于根据[(t2-t1)-(t4-t3)-Δlatency]÷2计算所述从设备与所述主设备之间的时间偏差；
    其中，t1为所述第一发送时间，t2为所述第一接收时间，t3为所述第二发送时间，t4为所述第二接收时间，Δlatency为所述双向延时差。
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