Remote Hardware Timestamp-Based Clock Synchronization

A method comprising:

• sending messages from a first device to a second device;
• recording time of departure values for at least some of the messages with respect to a clock of the first device;
• receiving at the first device a time value transfer message comprising time of reception values indicating times of reception of the messages at the second device with respect to a clock of the second device;
• computing a clock correction value based on the time of reception values and the time of departure values, wherein the clock correction value represents an offset between the clock of the first device and the clock of the second device;
• and
• sending the clock correction value from the first device to the second device.

An apparatus comprising:

• a network interface module configured to transmit and receive messages over a network;
• a clock module configured to generate clock values;
• a controller coupled to the network interface module and the clock module, wherein the controller is configured to:
• receive messages from a first apparatus;
• store time of reception values for the messages received in terms of clock values output by the clock module;
• send to an other apparatus a time value transfer message comprising the time of reception values;
• receive from the other apparatus a clock correction value computed by the other apparatus device on the basis of the time of reception values, wherein the clock correction value represents an offset between a clock of the first apparatus and the clock module;
• and
• adjust the clock module based on the clock correction value.

An apparatus comprising:

• a network interface module configured to transmit and receive messages over a network;
• a clock module configured to generate clock values;
• a controller coupled to the network interface module and the clock module, wherein the controller is configured to:
• send messages to an other apparatus;
• store time of departure values for at least some of the messages in terms of clock values output by the clock module;
• receive a time value transfer message comprising time of reception values indicating times of reception of the messages at the other apparatus with respect to a clock of the other apparatus;
• compute a clock correction value based on the time of reception values and the time of departure values, wherein the clock correction value represents an offset between the clock module and the clock of the other apparatus;
• and
• send the clock correction value to the other apparatus.

A processor readable tangible memory medium encoded with instructions that, when executed by a processor, cause the processor to:

• receive messages from a first device at a second device;
• store time of reception values for the messages received at the second device with respect to a clock of the second device;
• send from the second device to an other device a time value transfer message comprising the time of reception values;
• receive at the second device from the other device a clock correction value computed by the other device on the basis of the time of reception values, wherein the clock correction value represents an offset between a clock of the first device and the clock of the second device;
• and
• adjust the clock of the second device based on the clock correction value.

A processor readable tangible memory medium encoded with instructions that, when executed by a processor, cause the processor to:

• send messages from a first device to a second device;
• store time of departure values for at least some of the messages with respect to a clock of the first device;
• receive at the first device a time value transfer message comprising time of reception values indicating times of reception of the messages at the second device with respect to a clock of the second device;
• compute a clock correction value based on the time of reception values and the time of departure values, wherein the clock correction value represents an offset between the clock of the first device and the clock of the second device;
• and
• send the clock correction value from the first device to the second device.