Method, Ethernet device and Ethernet for clock synchronization

1. A method for synchronizing a clock of an Ethernet device, comprising:

receiving, by an optical module of a first Ethernet device, data sent by a second Ethernet device;

extracting, by a PHY layer unit of the first Ethernet device, a clock from the data;

sending, by the PHY layer unit, the clock to a MAC layer unit of the first Ethernet device; and

adjusting, by the MAC layer unit, the clock according to a local clock and taking the adjusted clock as a transmit clock of the first Ethernet device.

2. The method of claim 1 , wherein the receiving, by the optical module, data from the second Ethernet device and the extracting, by the PHY layer unit, the clock from the data comprises:

receiving, by an electrical/optical interface, the data sent by the second Ethernet device, wherein the optical module comprises the electrical/optical interface;

sending, by the electrical/optical interface, the data to the PHY layer unit through a serial-to-parallel conversion (SERDES) line; and

recovering, by the PHY layer unit, the clock of the SERDES line based on the transient 0 and 1 in a serial data stream by clock and data recovery (CDR).

3. A method for clock synchronization in an entire Ethernet, comprising:

synchronizing, by a first Ethernet device, its local clock to the clock of a second Ethernet device at an upper neighboring level according to the method of claim 2 ;

synchronizing, by a third Ethernet device at a lower neighboring level, its local clock to the clock of the first Ethernet device according to the method of claim 2 .

4. An Ethernet, comprising a first Ethernet device at a level and a second Ethernet device at an upper neighboring level,

wherein the first Ethernet device synchronizes its clock to the clock of the second Ethernet device according to the method of claim 2 .

5. The method of claim 1 wherein the sending the clock to a MAC layer unit of the first Ethernet device comprises:

sending the clock extracted from the data to the MAC layer unit through an Ethernet interface.

6. The method of claim 5 , wherein the adjusting the clock according to the local clock comprises:

making, by the MAC layer unit, adjustment to the clock, wherein the adjustment is frequency justification or jitter elimination.

7. The method of claim 6 , wherein the adjusting the clock according to the local clock further comprises:

adjusting a phase of the clock received from the PHY layer unit.

8. A method for clock synchronization in an entire Ethernet, comprising:

synchronizing, by a first Ethernet device, its local clock to the clock of a second Ethernet device at an upper neighboring level according to the method of claim 1 ;

synchronizing, by a third Ethernet device at a lower neighboring level, its local clock to the clock of the first Ethernet device according to the method of claim 1 .

9. The method of claim 8 , further comprising:

determining a fourth Ethernet device at the highest level, which takes the clock generated by itself as its local clock; and

sending data, by the fourth Ethernet device, to an Ethernet device at a lower neighboring level of the fourth Ethernet device.

10. An Ethernet device, comprising:

a receive unit, adapted to receive data sent to the Ethernet device from a second Ethernet device;

a PHY layer unit, adapted to receive data from the receive unit, extract a clock from the data and send the clock to a MAC layer unit; and

the MAC layer unit, adapted to adjust the clock received from the PHY layer unit according to a local clock and take the adjusted clock as a transmit clock of the Ethernet device.

11. The Ethernet device of claim 10 , wherein:

the receive unit sends data to the PHY layer unit through a serial-to-parallel conversion (SERDES) line; and

the PHY layer unit extracts the clock of the SERDES line based on the transient 0 and 1 in a serial data stream by clock and data recovery (CDR).

12. The Ethernet device of claim 10 , wherein:

the PHY layer unit sends the clock extracted from the data to the MAC layer unit through an Ethernet interface.

13. The Ethernet device of claim 12 , wherein:

the MAC layer unit makes an adjustment to clock received from the PHY layer unit, the adjustment including frequency justification or jitter elimination.

14. The Ethernet device of claim 13 , wherein:

the MAC layer unit further adjusts a phase of the clock received from the PHY layer unit.

15. An Ethernet, comprising a first Ethernet device at a level and a second Ethernet device at an upper neighboring level, wherein:

the first Ethernet device synchronizes its clock to the clock of the second Ethernet device according to the method of claim 1 .

16. The Ethernet of claim 15 , further comprising a third Ethernet device; wherein:

the third Ethernet device at the lower neighboring level synchronizes its clock to the clock of the first Ethernet device according to the method of claim 1 .

17. The Ethernet of claim 16 , wherein the second Ethernet device takes a clock generated by itself as its clock if the second Ethernet device is located at the highest level.

18. The Ethernet of claim 15 , wherein the first Ethernet device comprises:

a receive unit, adapted to receive data sent to the first Ethernet device from the second Ethernet device;

a PHY layer unit, adapted to receive data from the receive unit, extract a clock from the data and send the clock to a MAC layer unit; and

the MAC layer unit, adapted to adjust the clock received from the PHY layer unit according to a local clock and take the adjusted clock as a transmit clock of the first Ethernet device.