Inter-Packet Gap Network Clock Synchronization

• US 20080075128A1
• Filed: 04/16/2007
• Published: 03/27/2008
• Est. Priority Date: 09/25/2006
• Status: Active Grant

• Current Assignee: Futurewei Technologies Incorporated (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Futurewei Technologies Incorporated (Huawei Investment & Holding Co., Ltd.)
• Inventors: Fourcand, Serge Francois
• Granted Patent: US 8,295,310 B2
• Time in Patent Office: Days
• US Class Current: 370/520
• CPC Class Codes: H04J 3/0602 Systems characterised by the synchronising information used
• CPC Class Codes: H04J 3/065 using timestamps
• CPC Class Codes: H04J 3/0667 Bidirectional timestamps, e.g. NTP or PTP for compensation of clock drift and for compensation of propagation delays arrangements for monitoring round trip delays in packet switching networks H04L43/0864
• CPC Class Codes: H04L 12/403 with centralised control, e.g. polling

Abstract

A network component comprising at least one processor configured to implement a method comprising adding a clock synchronization data to a data stream comprising a plurality of Ethernet packets, wherein the clock synchronization data is located in a gap between two of the Ethernet packets. Also disclosed is a method comprising adding a clock synchronization data to a gap between a plurality of Ethernet packets in a data stream, wherein the clock synchronization data comprises a timestamp, a first bit that indicates whether the clock synchronization data is a request or an acknowledgement, and a second bit that indicates a requested operational mode.

Claims

1. A network component comprising:

at least one processor configured to implement a method comprising;

adding a clock synchronization data to a data stream comprising a plurality of Ethernet packets,

wherein the clock synchronization data is located in a gap between two of the Ethernet packets.

2. The component of claim 1 wherein the clock synchronization data does not modify the Ethernet packets.

3. The component of claim 1 wherein the clock synchronization data is four octets long.

4. The component of claim 1 wherein the clock synchronization data is added to the data stream at least once about every 125 microseconds.

5. The component of claim 1 wherein the clock synchronization data does not affect the bandwidth of the data stream.

6. The component of claim 1 wherein the clock synchronization data is not located in every gap between the Ethernet packets.

7. The component of claim 1 wherein the clock synchronization data replaces about two sets of idle characters.

8. The component of claim 1 wherein an idle character occurs after the clock synchronization data.

9. A method comprising:

adding a clock synchronization data to a gap between a plurality of Ethernet packets in a data stream, wherein the clock synchronization data comprises;

a timestamp;

a first bit that indicates whether the clock synchronization data is a request or an acknowledgement; and

a second bit that indicates a requested operational mode.

10. The method of claim 9 wherein the clock synchronization data indicates a quality of a clock.

11. The method of claim 9 wherein the clock synchronization data is about four octets long, the first bit is located at about a sixth bit in a fourth octet, and the second bit is located at about a seventh bit in the fourth octet.

12. The method of claim 9 wherein the clock synchronization data has a resolution of about 0.01 nanoseconds.

13. The component of claim 9 wherein the clock synchronization data has a range of no more than about 168 microseconds.

14. The method of claim 9 wherein the clock synchronization data has a period of no more than about 125 microseconds.

15. An Ethernet node comprising:

at least one processor configured to implement a method comprising;

recognizing the reception of a data stream from an upstream node, wherein the data stream comprises a plurality of Ethernet packets and a synchronization request comprising a timestamp;

synchronizing a clock with the timestamp; and

promoting the transmission of a response to the upstream node,

wherein the data stream has the same bandwidth as a data stream does not have the synchronization request and the timestamp.

16. The node of claim 15:

wherein the synchronization request is located in a gap between two of the Ethernet packets,

wherein the method further comprises transmitting a second data stream comprising a second plurality of Ethernet packets to the upstream node, and

wherein the response is located in a gap between two of the second Ethernet packets.

17. The node of claim 15:

wherein the timestamp is associated with a second clock in an upstream node,

wherein only a single timestamp is required to synchronize the clock with the second clock, and

wherein the clock is synchronized with the second clock in frequency.

18. The node of claim 15 wherein the synchronization request comprises a requested operational mode, and wherein the method further comprises transitioning to the requested operational mode.

19. The node of claim 15 wherein the synchronization request comprises a requested operational mode, and wherein the method further comprises maintaining a current operational mode when the requested operational mode is not supported.

20. The node of claim 15 wherein the synchronization request indicates the quality of a second clock in the upstream node, and wherein the response comprises a second synchronization request when the quality of the clock is greater than the quality of the second clock.