Clock synchronization using multiple network paths

• US 9,806,835 B2
• Filed: 05/09/2013
• Issued: 10/31/2017
• Est. Priority Date: 02/09/2012
• Status: Active Grant

• Current Assignee: Marvell Asia Pte Limited (Marvell Technology Group Limited)
• Original Assignee: Marvell International Limited (Marvell Technology Group Limited)
• Inventors: Mizrahi, Tal
• Primary Examiner(s): Orgad, Edan
• Assistant Examiner(s): MAGLO, EMMANUEL K
• Application Number:
  US13/890,921
• Publication Number:
  US 20130259049A1
• Time in Patent Office: 1,636 Days
• Field of Search: 370392
• CPC Class Codes: H04J 3/0602 Systems characterised by the synchronising information used
• CPC Class Codes: H04J 3/0664 unidirectional 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

Abstract

A network device includes one or more ports coupled to a network, and a time synchronization module. The time synchronization module processes (i) respective path information, and (ii) respective time synchronization information included in each of at least some of a plurality of time synchronization packets received from a master clock device over two or more different communication paths and via at least one of the one or more ports, wherein the respective path information indicates a respective communication path in the network via which the respective time synchronization packet was received. The time synchronization module determines a system time clock responsive to the processing of the path information and the time synchronization information included in the at least some of the plurality of time synchronization packets.

Claims

1. A network device, comprising:

one or more ports coupled to a network; and

one or more integrated circuit devices configured to;

process (i) respective path information, and (ii) respective time information included in each of at least some of a plurality of time synchronization packets received from a master clock device over two or more different communication paths and via at least one of the one or more ports, wherein time synchronization packets, of the plurality of time synchronization packets, are for synchronization of a system time clock in the network device with the master clock device, and wherein the respective path information indicates a respective communication path in the network via which the respective time synchronization packet was received,

responsive to processing of path information included in at least one time synchronization packet of the plurality of time synchronization packets, select path delay information corresponding to a particular communication path, selected from among the two or more different communication paths, over which the at least one time synchronization packet was received, and

determine a value of the system time clock (i) based on the selected path delay information and (ii) responsive to the processing of the time information included in the at least one time synchronization packet.

2. The network device of claim 1, wherein:

the respective path information includes a respective set of one or more addresses; and

the one or more integrated circuit devices are configured to identify that the respective time synchronization packet was received via a particular communication path using the respective set of one or more addresses.

3. The network device of claim 2, wherein:

the respective set of one or more addresses includes (i) a respective source IP address, and (ii) a respective destination IP address; and

the one or more integrated circuit devices are configured to identify that the respective time synchronization packet was received via the particular communication path using (i) the respective source IP address, and (ii) the respective destination IP address.

4. The network device of claim 2, wherein:

the respective set of one or more addresses includes a respective destination IP address; and

the one or more integrated circuit devices are configured to identify that the respective time synchronization packet was received via the particular communication path using the respective destination IP address.

5. The network device of claim 2, wherein:

the respective set of one or more addresses includes a respective source IP address; and

the one or more integrated circuit devices are configured to identify that the respective time synchronization packet was received via the particular communication path using the respective source IP address.

6. The network device of claim 1, wherein:

the respective path information includes a respective virtual local area network identifier (VLAN ID); and

the one or more integrated circuit devices are configured to identify that the respective time synchronization packet was received via a particular communication path using the respective VLAN ID.

7. The network device of claim 6, wherein:

the respective path information includes a respective Layer-2 address; and

the one or more integrated circuit devices are configured to identify that the respective time synchronization packet was received via the particular communication path further using the Layer-2 address.

8. The network device of claim 7, wherein:

the respective Layer-2 address is a backbone destination address (B-DA).

9. The network device of claim 1, wherein:

the respective path information includes a respective user datagram protocol (UDP) port field; and

the one or more integrated circuit devices are configured to identify that the respective time synchronization packet was received via a particular communication path using the respective UDP port field.

10. The network device of claim 1, wherein:

the respective path information includes a dedicated path identifier (ID) field in the respective time synchronization packet; and

the one or more integrated circuit devices are configured to identify that the respective time synchronization packet was received via a particular communication path using the respective dedicated path ID field.

11. The network device of claim 1, wherein:

the network device comprises multiple ports coupled to the network; and

the one or more integrated circuit devices are configured to identify that the respective time synchronization packet was received via a particular communication path further based on via which one of the multiple ports the respective time synchronization packet was received.

12. A method, comprising:

receiving a plurality of time synchronization packets from a master clock device over two or more different communication paths via one or more ports coupled to a network, wherein time synchronization packets, of the plurality of time synchronization packets, are for synchronization of a system time clock in a network device with the master clock device, and wherein each time synchronization packet includes (i) respective path information, and (ii) respective time information, wherein the respective path information indicates a respective communication path in the network via which the respective time synchronization packet was received;

for each of at least some of the plurality of time synchronization packets, processing (i) respective path information included in the received time synchronization packets, and (ii) respective time information included in the received time synchronization packets;

responsive to processing of path information included in at least one time synchronization packet of the at least some of the plurality of time synchronization packets, selecting path delay information corresponding to a particular communication path, selected from among the two or more different communication paths, over which the at least one time synchronization packet was received; and

determining a value of the system time clock (i) based on the selected path delay information and (ii) responsive to the processing of the time information included in the at least one time synchronization packet.

13. The method of claim 12, wherein:

the respective path information includes a respective set of one or more addresses; and

the method further comprises, for each of at least some of the plurality of time synchronization packets, identifying that the respective time synchronization packet was received via a particular communication path using the respective set of one or more addresses.

14. The method of claim 13, wherein:

the respective set of one or more addresses includes (i) a respective source IP address, and (ii) a respective destination IP address; and

identifying that the respective time synchronization packet was received via the particular communication path includes using (i) the respective source IP address, and (ii) the respective destination IP address to identify that the respective time synchronization packet was received via the particular communication path.

15. The method of claim 13, wherein:

the respective set of one or more addresses includes a respective destination IP address; and

identifying that the respective time synchronization packet was received via the particular communication path includes using the respective destination IP address to identify that the respective time synchronization packet was received via the particular communication path.

16. The method of claim 13, wherein:

the respective set of one or more addresses includes a respective source IP address; and

identifying that the respective time synchronization packet was received via the particular communication path includes using the respective source IP address to identify that the respective time synchronization packet was received via the particular communication path.

17. The method of claim 12, wherein:

the respective path information includes a respective VLAN ID; and

identifying that the respective time synchronization packet was received via the particular communication path includes using the respective VLAN ID to identify that the respective time synchronization packet was received via the particular communication path.

18. The method of claim 17, wherein:

the respective path information includes a respective Layer-2 address; and

identifying that the respective time synchronization packet was received via the particular communication path includes further using the respective Layer-2 address.

19. The method of claim 18, wherein:

the respective Layer-2 address is a backbone destination address (B-DA).

20. The method of claim 12, wherein:

the respective path information includes a respective user datagram protocol (UDP) port field; and

identifying that the respective time synchronization packet was received via the particular communication path includes further using the respective UDP port field.

21. The method of claim 12, wherein:

the respective path information includes a dedicated path identifier (ID) field in the respective time synchronization packet; and

identifying that the respective time synchronization packet was received via the particular communication path includes further using the respective dedicated path ID field.

22. The method of claim 12, wherein:

receiving the plurality of time synchronization packets from the master clock device over two or more different communication paths comprises receiving the plurality of time synchronization packets via multiple ports coupled to the network; and

identifying that the respective time synchronization packet was received via the particular communication path is further based on via which one of the multiple ports the respective time synchronization packet was received.

23. A system, comprising:

a first network device including;

one or more first ports coupled to a communication network, and

one or more integrated circuit devices configured to;

generate a plurality of time synchronization packets for synchronization of a system time clock in a network device with a master clock, each time synchronization packet having (i) respective path information, and (ii) respective time information, wherein the respective path information indicates a respective communication path in the communication network via which the respective time synchronization packet is to be transmitted, and

cause the plurality of time synchronization packets to be transmitted (i) via at least one of the one or more first ports, and (ii) via multiple different communication paths in the communication network; and

a second network device communicatively coupled to the first network device via the communication network, the second network device including;

one or more second ports coupled to the communication network;

one or more integrated circuit devices configured to;

process (i) respective path information, and (ii) respective time information included in each of at least some of the plurality of time synchronization packets transmitted by the first network device via at least one of the one or more ports,

responsive to processing of path information included in at least one time synchronization packet of the at least some of the plurality of time synchronization packets, select path delay information corresponding to a particular communication path, selected from among the multiple different communication paths, over which the at least one time synchronization packet was transmitted by the first communication device, and

determine a value of the system time clock (i) based on the selected path delay information and (ii) responsive to the processing of the time information included in the at least one time synchronization packet.

24. The system of claim 23, further comprising at least a portion of the communication network.

25. The system of claim 24, further comprising all of the communication network.