Time synchronization method and system, and node device

A time synchronization method, comprising:

• sending, by a first node, a first time packet at a first time over a first working wavelength;
• receiving, by a second node, the first time packet at a second time;
• sending, by the first node, a second time packet at a third time over a second working wavelength;
• receiving, by the second node, the second time packet at a fourth time;
• and
• obtaining a time synchronization error between the second node and the first node according to the first time, the second time, the third time, the fourth time, a first signal transmission rate corresponding to the first working wavelength, a second signal transmission rate corresponding to the second working wavelength, a signal transmission rate of a wavelength used for transmitting an 1588 protocol packet from the first node to the second node, and a sum of path delays in both directions between the first node and the second node as calculated through the 1588 protocol, and synchronizing local time of the second node with local time of the first node.

A time synchronization method, comprising:

• sending, by a first node, a first time packet at a first time over a first working wavelength, wherein the first time packet carries the first time;
• receiving, by a second node, the first time packet at a second time, and extracting the first time;
• sending, by the first node, a second time packet at a third time over a second working wavelength, wherein the second time packet carries the third time;
• receiving, by the second node, the second time packet at a fourth time, and extracting the third time;
• sending, by the second node, a third time packet at a fifth time over a third working wavelength;
• receiving, by the first node, the third time packet at a sixth time;
• sending, by the second node, a fourth time packet at a seventh time over a fourth working wavelength;
• receiving, by the first node, the fourth time packet at an eighth time;
• and
• obtaining, by the second node, a time synchronization error between the second node and the first node according to the first time, the second time, the third time, the fourth time, the fifth time, the sixth time, the seventh time, the eighth time, a first signal transmission rate corresponding to the first working wavelength, a second signal transmission rate corresponding to the second working wavelength, a third signal transmission rate corresponding to the third working wavelength, a fourth signal transmission rate corresponding to the fourth working wavelength, a signal transmission rate of a wavelength used for transmitting an 1588 protocol packet from the first node to the second node, and a signal transmission rate of a wavelength used for transmitting the 1588 protocol packet from the second node to the first node, and synchronizing local time of the second node with local time of the first node.

A node device, comprising:

• a line processing module, configured to receive a first time packet sent by a first node over a first working wavelength, and a second time packet sent by the first node over a second working wavelength;
• a packet processing module, configured to:
• record receiving time of the first time packet and receiving time of the second time packet;
• resolve the first time packet and the second time packet, and extract sending time of the first time packet carried in the first time packet, and sending time of the second time packet carried in the second time packet;
• a time calculating module, configured to calculate an absolute time deviation between the node device and the first node according to the sending time of the first time packet, the sending time of the second time packet, the receiving time of the first time packet, the receiving time of the second time packet, a first signal transmission rate corresponding to the first working wavelength, and a second signal transmission rate corresponding to the second working wavelength;
• and
• a local time module, configured to:
• deliver the receiving time of the first time packet and the receiving time of the second time packet to the packet processing module;
• and subtract the absolute time deviation from local time of the node device to obtain local time synchronized to local time of the first node.

A node device, comprising:

• a line processing module, configured to send a first time packet to a second node over a first working wavelength, send a second time packet to the second node over a second working wavelength, and receive a third time packet sent by the second node;
• a packet processing module, configured to:
• encapsulate the first time packet and the second time packet, wherein the first time packet carries sending time of the first time packet, and the second time packet carries sending time of the second time packet;
• and resolve the third time packet and extract an absolute time deviation between the node device and the second node carried in the third time packet, wherein
• the absolute time deviation is calculated by the second node according to the sending time of the first time packet, the sending time of the second time packet, receiving time of the first time packet, receiving time of the second time packet, a first signal transmission rate corresponding to the first working wavelength, and a second signal transmission rate corresponding to the second working wavelength;
• and
• a local time module, configured to:
• deliver the sending time of the first time packet and the sending time of the second time packet to the packet processing module;
• and add the absolute time deviation to local time of the node device to obtain local time synchronized to local time of the second node.

A node device, comprising:

• a line processing module, configured to send a first time packet to a second node over a first working wavelength, send a second time packet to the second node over a second working wavelength, and receive a fourth time packet sent by the second node;
• a packet processing module, configured to:
• encapsulate the first time packet and the second time packet, and record sending time of the first time packet and sending time of the second time packet;
• resolve the fourth time packet, and extract receiving time of the first time packet and receiving time of the second time packet carried in the fourth time packet;
• a time calculating module, configured to calculate an absolute time deviation between the node device and the second node according to the sending time of the first time packet, the sending time of the second time packet, the receiving time of the first time packet, the receiving time of the second time packet, a first signal transmission rate corresponding to the first working wavelength, and a second signal transmission rate corresponding to the second working wavelength;
• and
• a local time module, configured to:
• deliver the sending time of the first time packet and the sending time of the second time packet to the packet processing module;
• and add the absolute time deviation to local time of the node device to obtain local time synchronized to local time of the second node.

A node device, comprising:

• a line processing module, configured to receive a first time packet sent by a first node over a first working wavelength, and a second time packet sent by the first node over a second working wavelength;
• a packet processing module, configured to:
• record receiving time of the first time packet and receiving time of the second time packet;
• resolve the first time packet and the second time packet, and extract sending time of the first time packet carried in the first time packet, and sending time of the second time packet carried in the second time packet;
• an 1588 protocol module, configured to execute the 1588 protocol to obtain a sum of path delays in both directions between the first node and the second node, and synchronize local time of the node device to local time of the first node through the 1588 protocol;
• a time calculating module, configured to calculate a time synchronization error between the node device and the first node according to the sending time of the first time packet, the sending time of the second time packet, the receiving time of the first time packet, the receiving time of the second time packet, a first signal transmission rate corresponding to the first working wavelength, a second signal transmission rate corresponding to the second working wavelength, a signal transmission rate of a wavelength used for transmitting an 1588 protocol packet from the first node to the second node, and the sum of the path delays in both directions;
• and
• a local time module, configured to:
• deliver the receiving time of the first time packet and the receiving time of the second time packet to the packet processing module, deliver the local time to the 1588 protocol module, and add the time synchronization error to the node device's local time synchronized through the 1588 protocol.

A node device, comprising:

• a line processing module, configured to send a first time packet to a second node over a first working wavelength, send a second time packet to the second node over a second working wavelength, and receive a sixth time packet sent by the second node;
• a packet processing module, configured to:
• encapsulate the first time packet and the second time packet, wherein the first time packet carries sending time of the first time packet, and the second time packet carries sending time of the second time packet;
• and resolve the sixth time packet and extract a line distance from the first node to the second node or a path delay of transmitting an 1588 protocol packet from the first node to the second node carried in the sixth time packet, wherein
• the line distance from the first node to the second node is calculated by the second node according to the sending time of the first time packet, the sending time of the second time packet, receiving time of the first time packet, receiving time of the second time packet, a first signal transmission rate corresponding to the first working wavelength, and a second signal transmission rate corresponding to the second working wavelength;
• the path delay of transmitting the 1588 protocol packet from the first node to the second node is calculated by the second node according to the sending time of the first time packet, the sending time of the second time packet, the receiving time of the first time packet, the receiving time of the second time packet, the first signal transmission rate corresponding to the first working wavelength, the second signal transmission rate corresponding to the second working wavelength, and a signal transmission rate of a wavelength used for transmitting the 1588 protocol packet from the first node to the second node;
• an 1588 protocol module, configured to execute the 1588 protocol to obtain a sum of path delays in both directions between the first node and the second node, and synchronize local time of the node device to local time of the second node through the 1588 protocol;
• a time calculating module, configured to calculate a time synchronization error between the second node and the first node according to the line distance from the first node to the second node, the signal transmission rate of the wavelength used for transmitting the 1588 protocol packet from the first node to the second node, and the sum of the path delays in both directions between the first node and the second node;
• or according to the path delay of transmitting the 1588 protocol packet from the first node to the second node, and the sum of the path delays in both directions between the first node and the second node;
• and
• a local time module, configured to:
• deliver the sending time of the first time packet and the sending time of the second time packet to the packet processing module, deliver the local time to the 1588 protocol module, and subtract the time synchronization error from the node device's local time synchronized through the 1588 protocol.

A node device, comprising:

• a line processing module, configured to:
• receive a first time packet sent by a first node over a first working wavelength and a second time packet sent by the first node over a second working wavelength;
• send a third time packet to the first node over a third working wavelength, and send a fourth time packet to the first node over a fourth working wavelength;
• and receive an eighth time packet sent by the first node;
• a packet processing module, configured to:
• record receiving time of the first time packet and receiving time of the second time packet;
• resolve the first time packet and the second time packet, and extract sending time of the first time packet carried in the first time packet, and sending time of the second time packet carried in the second time packet;
• encapsulate the third time packet and the fourth time packet, wherein the third time packet carries sending time of the third time packet, and the fourth time packet carries sending time of the fourth time packet;
• and resolve the eighth time packet and extract a path delay of transmitting an 1588 protocol packet from the second node to the first node carried in the eighth time packet, wherein:
• the path delay of transmitting the 1588 protocol packet from the second node to the first node is calculated by the first node according to the sending time of the third time packet, the sending time of the fourth time packet, the receiving time of the third time packet, the receiving time of the fourth time packet, a third transmission rate corresponding to the third working wavelength, a fourth transmission rate corresponding to the fourth working wavelength, and a signal transmission rate of a wavelength used for transmitting the 1588 protocol packet from the second node to the first node;
• an 1588 protocol module, configured to execute the 1588 protocol, and synchronize local time of the node device to local time of the first node through the 1588 protocol;
• a time calculating module, configured to calculate a time synchronization error between the second node and the first node according to the sending time of the first time packet, the sending time of the second time packet, the receiving time of the first time packet, the receiving time of the second time packet, a first signal transmission rate corresponding to the first working wavelength, a second signal transmission rate corresponding to the second working wavelength, the path delay of transmitting the 1588 protocol packet from the second node to the first node, the signal transmission rate of the wavelength used for transmitting the 1588 protocol packet from the first node to the second node;
• and
• a local time module, configured to:
• deliver the receiving time of the first time packet, the receiving time of the second time packet, the sending time of the third time packet, and the sending time of the fourth time packet to the packet processing module, deliver the local time to the 1588 protocol module, and add the time synchronization error to the node device's local time synchronized through the 1588 protocol.