Synchronizing state information between control units

• US 8,799,511 B1
• Filed: 06/11/2010
• Issued: 08/05/2014
• Est. Priority Date: 10/03/2003
• Status: Active Grant

• Current Assignee: Juniper Networks Incorporated
• Original Assignee: Juniper Networks Incorporated
• Inventors: Balakrishna, Raghunath, Wang, Shine-chu, Krishnaswamy, Umesh, Chadalavada, Bharani, Kumar, Sandeep, Tuplur, Raj, Sivaramakrishnan, Rajagopalan
• Primary Examiner(s): Donabed, Ninos
• Application Number:
  US12/814,198
• Time in Patent Office: 1,516 Days
• Field of Search: None
• US Class Current: 709/242
• CPC Class Codes: G06F 11/2038 with a single idle spare processing component
• CPC Class Codes: G06F 11/2097 maintaining the standby controller/processing unit updated initialisation or re-synchronisation thereof G06F11/1658 and subgroups
• CPC Class Codes: H04L 12/66 Arrangements for connecting between networks having differing types of switching systems, e.g. gateways

Abstract

Techniques are described for synchronizing state information between a plurality of control units. A router, for example, is described that includes a primary control unit and a standby control unit. The primary control unit maintains router resources to ensure operation of the router. To ensure operation, the primary control unit receives state information from the router resources and maintains the state information for consumers, i.e. router resources that require or “consume” state information. Prior to updating the consumers with the state information, the primary control unit synchronizes the state information with the standby control unit. In the event the primary control unit fails, the standby control unit assumes control of the router resources. Upon assuming control, the standby control unit resumes updating the consumers with state information without having to “relearn” state information, e.g., by way of power cycling the router resources to a known state.

Claims

1. A method comprising:

managing state information within a primary control unit included within a device for one or more consumers included within the device, wherein the state information is stored in a temporally-ordered data structure having a commit proposal and commit marker pair for each of the one or more consumers that identifies a portion of the state information to be consumed by the respective one or more consumers, wherein the commit proposal identifies a most recent object of the temporally-ordered data structure that has been communicated to a corresponding one of the one or more consumers and the commit marker identifies a most recent object of the temporally-ordered data structure that has been communicated to the corresponding one of the one or more consumers and for which an acknowledgement has been received from the corresponding one of the one or more consumers; and

communicating changes to the state information to a standby control unit prior to communicating the changes to the one or more consumers of the state information by replicating the temporally-ordered data structure and the corresponding commit proposal and commit marker pair for each of the one or more consumers.

2. The method of claim 1, wherein communicating changes to the state information to a standby control unit comprises communicating changes to the state in accordance with an order that requires the changes to be communicated to the standby control unit prior to communicating the changes to the consumer of the state information.

3. The method of claim 1, further comprising communicating changes to the state information to the consumers in accordance with the data structure by utilizing the commit proposal and commit marker pairs.

4. The method of claim 3, wherein utilizing the commit proposal and commit marker pairs comprises:

upon communicating the most recent object to the corresponding one of the one or more consumers, setting the commit proposal to identify the most recent object of the temporally-ordered data structure communicated to the corresponding one of the one or more consumers; and

upon receiving the acknowledgement from the corresponding one of the one or more consumers, setting the commit marker to identify the most recent object of the temporally-ordered data structure that has been communicated to the corresponding one of the one or more consumers and for which the acknowledgement has been received from the corresponding one of the one or more consumers.

5. The method of claim 4, further comprising setting a flag that indicates to the consumer that the commit proposal has been set.

6. The method of claim 4, further comprising resetting the commit marker to the object identified by the commit proposal in response to receiving the acknowledgement.

7. The method of claim 3, wherein utilizing the commit marker and commit proposal pairs further comprises deleting a least recent object of the temporally-ordered data structure that is not bounded by the commit markers and commit proposal pairs.

8. The method of claim 1, further comprising

communicating the portion of the replicated temporally-ordered data structure that is bounded by the replicated commit proposal and commit marker pairs to the one or more consumers from the standby control unit in the event the primary control unit fails;

and

issuing a communication from the primary control unit to cause the standby control unit to set the replicated commit proposals to identify a most recent object of the replicated temporally-ordered data structure that has not been acknowledged by the one or more consumers.

9. The method of claim 8, further comprising issuing a communication from the primary control unit to cause the standby control unit to set the replicated commit markers to identify a most recent object of the replicated temporally-ordered data structure that has been communicated to the one or more consumers and for which an acknowledgement has been received from the one or more consumers, wherein issuing the communication to cause the standby control unit to set the replicated commit markers further causes the standby control unit to set the replicated commit markers to the object identified by the replicated commit proposals in response to receiving the acknowledgement.

10. The method of claim 1,

wherein managing state information comprises storing the state information within a set of objects, and

wherein the method further comprises:

wherein the change comprises one of a plurality of changes,

wherein receiving the changes comprises receiving event messages indicating the changes to the state information, and

the method further comprising linking the objects of the data structure in accordance with an order in which the event messages are received to form a temporally-ordered data structure.

11. A device comprising:

a primary control unit;

a standby control unit; and

one or more consumers,

wherein the primary control unit manages state information for the one or more consumers included within the device, wherein the state information is stored in a temporally-ordered data structure having a commit proposal and commit marker pair for each of the one or more consumers that identifies a portion of the state information to be consumed by the respective one or more consumers and communicates changes to the state information to the standby control unit prior to communicating the changes to the one or more consumers of the state information by replicating the temporally-ordered data structure and the corresponding commit proposal and commit marker pair for each of the one or more consumers, and wherein the commit proposal identifies a most recent object of the temporally-ordered data structure that has been communicated to a corresponding one of the one or more consumers and the commit marker identifies a most recent object of the temporally-ordered data structure that has been communicated to the corresponding one of the one or more consumers and for which an acknowledgement has been received from the corresponding one of the one or more consumers.

12. The device of claim 11, wherein communicating changes to the state information to the standby control unit comprises communicating the change to the state information in accordance with an order that requires the change to be communicated to the standby control unit prior to communicating the change to the consumer.

13. The device of claim 11, wherein the primary control unit communicate changes to the state information to the consumer in accordance with the temporally-ordered data structure.

14. The device of claim 11, wherein the primary control unit, upon communicating the most recent object to the corresponding one of the one or more consumers, sets the commit proposal to identify the most recent object of the temporally-ordered data structure that has been communicated to the corresponding one of the one or more consumers, and upon receiving the acknowledgement from the corresponding one of the one or more consumers, sets the commit marker to identify the most recent object of the temporally-ordered data structure that has been communicated to the consumer and for which the acknowledgement has been received from the corresponding one of the one or more consumers.

15. The device of claim 14, wherein the primary control unit sets a flag that indicates to the corresponding one of the one or more consumers that the commit proposal has been set.

16. The device of claim 14, wherein the primary control unit further sets the commit marker to the object identified by the commit proposal in response to receiving the acknowledgement.

17. The device of claim 11,

wherein the primary control unit replicates the commit proposal and commit marker pairs to the standby control unit and communicates a portion of the replicated temporally-ordered data structure that is bounded by the commit proposal and commit marker pairs to the one or more consumers from the standby control unit in the event the primary control unit fails, and

wherein the primary control unit issues a communication that causes the standby control unit to set the replicated commit proposals to identify a most recent object of the temporally-ordered replicated data structure that has not been acknowledged by the one or more consumers.

18. The device of claim 17,

wherein the primary control unit issues a communication that causes the standby control unit to set the replicated commit markers to identify a most recent object of the temporally-ordered replicated data structure that has been communicated to the one or more consumers and for which an acknowledgement has been received from the one or more consumers, and

wherein the communication that causes the standby control unit to set the replicated commit markers further causes the standby control unit to set the replicated commit markers to the object identified by the replicated commit proposals in response to receiving the acknowledgement.

19. The device of claim 11, wherein the primary control unit utilizes the commit markers and commit proposal pairs to delete a least recent object of the temporally ordered data structure that does not include the commit marker and commit proposal pairs.

20. The device of claim 11, wherein the primary control unit receives event messages indicating changes to the state information, and links objects of the data structure in accordance with an order in which the event messages are received to form the temporally-ordered data structure.