System and method for establishing processor redundancy

• US 6,460,146 B1
• Filed: 12/04/1998
• Issued: 10/01/2002
• Est. Priority Date: 12/04/1998
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: May, William, Moberg, Kenneth
• Primary Examiner(s): Baderman, Scott
• Assistant Examiner(s): Ziemer, Rita A
• Application Number:
  US09/205,577
• Time in Patent Office: 1,397 Days
• Field of Search: 714/10, 709/222, 709/238, 712/11, 712/14, 712/15, 712/20
• US Class Current: 714/10
• CPC Class Codes: G06F 11/2023 Failover techniques
• CPC Class Codes: G06F 11/2035 without idle spare hardware

Abstract

The present invention relates to providing processor redundancy in a system such as a router. According to an embodiment of the present invention, in a system having two or more processors, initialization sequence is started. During the initialization sequence, a redundancy subsystem is initialized. The redundancy subsystem identifies the projects or assignments that are to be off loaded from the primary processor to the secondary processor. According to an embodiment of the present invention, the initialization sequence is then suspended and a discovery process is performed. During the discovery process, it is determined whether the processor running the initialization sequence is a primary or a secondary processor. If it is a secondary processor, then the initialization sequence remains suspended and the secondary processor monitors the health of the primary processor until a failure of the primary processor occurs. If a primary processor failure occurs, then the initialization process is resumed for the secondary processor, hence establishing the secondary processor as the new primary processor.

Claims

1. A method for establishing router redundancy, comprising:

providing a router processor;

suspending an initialization sequence of the router processor;

determining whether the router processor is a secondary processor;

resuming the initialization sequence if the router processor is not a secondary processor; and

continuing to suspend the initialization sequence of the router processor if the router processor is a secondary processor, whereby the router processor remains in a partially initialized state such that it would be ready to resume and complete the previously suspended initialization process in the event it were to become necessary for the router processor to become a primary processor.

2. The method of claim 1, further comprising monitoring a health of the secondary processor if the router processor is not the secondary processor.

3. The method of claim 1, further comprising monitoring a health of a primary processor if the router processor is the secondary processor.

4. The method of claim 1, further comprising resuming the initialization sequence if a predetermined event occurs and if the router processor is the secondary processor.

5. The method of claim 4, wherein the predetermined event includes a failure of a primary processor.

6. The method of claim 4, wherein the predetermined event includes a removal of a primary processor card.

7. The method of claim 4, wherein the predetermined event includes receiving a command to switch functions with a primary processor.

8. The method of claim 1, wherein the initialization sequence includes initializing a redundancy subsystem.

9. The method of claim 8, wherein the initializing the redundancy subsystem occurs prior to suspending the initialization sequence of the router processor.

10. The method of claim 1, wherein the secondary processor may perform processing that is off-loaded by a primary processor.

11. A system for establishing router processor redundancy, comprising:

a router processor configured to suspend an initialization sequence of the router processor, the router processor also being configured to;

determine whether it is a secondary processor, resume the initialization sequence if the router processor is not a secondary processor; and

continue to suspend the initialization sequence of the router processor if the router processor is a secondary processor;

whereby the router processor remains in a partially initialized state such that it would be ready to resume and complete the previously suspended initialization process in the event it were to become necessary for the router processor to become a primary processor; and

a memory coupled to the router processor, the memory being configured to provide instructions to the router processor.

12. The system of claim 11, further comprising monitoring a health of the secondary processor if the router processor is not the secondary processor.

13. The system of claim 11, further comprising monitoring a health of a primary processor if the router processor is the secondary processor.

14. The system of claim 11, further comprising resuming the initialization sequence if a predetermined event occurs and if the router processor is the secondary processor.

15. The system of claim 14, wherein the predetermined event includes a failure of a primary processor.

16. The system of claim 11, wherein the secondary processor may perform processing that is off-loaded by a primary processor.

17. The system of claim 11, further comprising a second router processor configured to suspend an initialization sequence of the second router processor, the second router processor also being configured to determine whether it is a secondary processor, and resuming the initialization sequence if the second router processor is not a secondary processor.

18. A computer program product for establishing processor redundancy, comprising:

computer code suspending an initialization sequence of a router processor;

computer code determining whether the router processor is a secondary processor;

computer code resuming the initialization sequence if the router processor is not a secondary processor;

computer code continuing to suspend the initialization sequence of the router processor if the router processor is a secondary processor, whereby the router processor remains in a partially initialized state such that it would be ready to resume and complete the previously suspended initialization process in the event it were to become necessary for the router processor to become a primary processor; and

a computer readable medium that stores the computer codes.

19. The computer program product of claim 18, wherein the computer readable medium is selected from the group consisting of CD-ROM, floppy disk, tape, flash memory, system memory, hard drive, and data signal embodied in a carrier wave.