Inter-Packet Gap Network Clock Synchronization

• US 20130051407A1
• Filed: 09/21/2012
• Published: 02/28/2013
• 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 8,982,912 B2
• Time in Patent Office: Days
• US Class Current: 370/514
• 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 a processor configured to receive a data stream from an upstream node, wherein the data stream comprises a plurality of Ethernet packets and a synchronization request comprising a timestamp, synchronize a clock with the timestamp, and transmit a response to the upstream node, wherein the data stream has the same bandwidth as a second data stream that does not have the synchronization request and the timestamp.

Claims

1. A network component comprising:

a processor configured to;

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

synchronize a clock with the timestamp; and

transmit a response to the upstream node,

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

2. The network component of claim 1, wherein the processor is further configured to transmit 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.

3. The network component of claim 1, wherein the timestamp is associated with a second clock in an upstream node, and wherein the clock is synchronized with the second clock in frequency.

4. The network component of claim 3, wherein only a single timestamp is required to synchronize the clock with the second clock.

5. The network component of claim 1, wherein the synchronization request comprises a requested operational mode, and wherein the logic further causes the processor to transition to the requested operational mode.

6. The network component of claim 1, wherein the synchronization request comprises a requested operational mode, and wherein the logic further causes the processor to maintain a current operational mode when the requested operational mode is not supported.

7. The network component of claim 1, 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.

8. The network component of claim 1, wherein the synchronization request is located in a gap between two of the Ethernet packets.

9. The network component of claim 8, wherein the clock request is not located in every gap between the Ethernet packets.

10. The network component of claim 8, wherein the clock synchronization request comprises a first bit that indicates the clock synchronization request is a request for clock synchronization.

11. The network component of claim 8, wherein the upstream node is configured to add the timestamp to the synchronization request and transmit the synchronization request in the data stream, and wherein the timestamp corresponds to an upstream clock associated with the upstream node.

12. The network component of claim 11, wherein the timestamp synchronizes the upstream clock with the clock, and wherein the logic further causes the processor to establish a synchronization window with the upstream node.

13. The network component comprising:

a processor configured to;

receive a clock synchronization data in a data stream, wherein the clock synchronization data comprises a timestamp and a control header that indicates a requested operational mode;

determine whether the network component supports the requested operational mode; and

synchronize a clock with the clock synchronization data when the network component supports the operational mode,

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

14. The network component of claim 13, wherein the clock is synchronized using the timestamp, and wherein the processor is further configured to transmit a response to a upstream node.

15. The network component of claim 13, wherein a first idle character occurs before the clock synchronization data and a second idle character occurs after the clock synchronization data.

16. The network component of claim 13, wherein the clock synchronization data is about four octets long, wherein a first bit in the control header indicates whether the clock synchronization data is a request or an acknowledgement, and wherein a second bit indicates the operation mode.

17. A method comprising:

receiving a first synchronization packet located in an inter-packet gap (IPG) of a first data stream at a downstream node, wherein the downstream node supports an operational mode indicated in the synchronization packet;

synchronizing a clock with the synchronization packet, wherein the synchronization packet comprises a timestamp and a control header; and

transmitting a second synchronization packet to an upstream node,

wherein the data stream has the same bandwidth as a second data stream that does not have the synchronization packet and the timestamp in the IPG.

18. The method in 17, wherein the control header indicates whether the synchronization packet is a request for clock synchronization or an acknowledgement for clock synchronization, wherein the control header indicates the operational mode, and wherein the synchronization packet is discarded when the downstream nodes does not support the operational mode.

19. The method 17, wherein the first synchronization packet comprises a timestamp, wherein the timestamp is associated with a clock in an upstream node, and wherein the clock is synchronized with the second clock in frequency.

20. The method 17, a second synchronization packet comprises a timestamp, wherein the timestamp is associated with a clock in an upstream node, and wherein the second synchronization packet is located in the inter-packet gap (IPG) of a third data stream.