System and method for discovering relative states of processors

• US 6,286,048 B1
• Filed: 12/04/1998
• Issued: 09/04/2001
• 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: Moberg, Kenneth
• Primary Examiner(s): WILEY, DAVID ARMAND
• Application Number:
  US09/205,554
• Time in Patent Office: 1,005 Days
• Field of Search: 709/204, 709/105, 709/226, 709/238, 709/239, 709/235, 709/243, 709/225, 714/11, 714/13, 370/219, 370/254, 370/392
• US Class Current: 709/225
• CPC Class Codes: H04L 45/00 Routing or path finding of packets in data switching networks routing or path finding in wireless networks H04W40/00
• CPC Class Codes: H04L 45/22 Alternate routing
• CPC Class Codes: H04L 45/28 using route fault recovery

Abstract

According to an embodiment of the present invention, two routers coupled through a network, such as a local access network (LAN), may be used to serve the function of redundancy to avoid the failure of a connection. The LAN may be used as a backplane to substitute for a bus between two processors. According to an embodiment of the present invention, the two routers may send their medium access control (MAC) addresses to each other and compare these MAC addresses. The router associated with the MAC address that meets a predetermined criteria may be deemed as a primary router and the other router can be deemed as a secondary router. An example of meeting the predetermined criteria is the router associated with the lower MAC address. Once processor states, such as stand alone, primary, and secondary, are established for the two routers, the primary router may serve the function of a standard router, while the secondary router monitors the health of the primary router and becomes a primary router should the original primary router have a failure.

Claims

1. A method for determining a state of a router comprising:

providing a first criteria and a second criteria, wherein the first criteria is associated with a first router and the second criteria is associated with a second router, and wherein the first router and second router are coupled to each other;

comparing the first criteria and the second criteria; and

determining whether the first router is a primary router, wherein the primary router serves a function of a standard router.

2. The method of claim 1, wherein the first criteria is a medium access control (MAC) address.

3. The method of claim 1, wherein the first router and the second router are coupled to each other in a network environment.

4. The method of claim 1, wherein the first router is a primary router if the first criteria meets a predetermined criteria better than the second criteria.

5. The method of claim 1, wherein the first router is a secondary router if the second criteria meets a predetermined criteria better than the first criteria.

6. The method of claim 1, wherein a frame is sent by the first router to the second router to indicate the first criteria.

7. The method of claim 1, wherein a frame is sent by the second router to the first router to indicate the second criteria.

8. A system for determining a state of a router comprising:

means for providing a first criteria and a second criteria, wherein the first criteria is associated with a first router and the second criteria is associated with a second router, and wherein the first router and second router are coupled to each other;

means for comparing the first criteria and the second criteria; and

determining whether the first router is a primary router, wherein the primary router serves a function of a standard router.

9. A system for determining a state of a processor comprising:

a first router providing a first criteria;

a second router coupled with the first router, the second router providing a second criteria;

wherein the second router includes a processor, the processor being configured to compare the first criteria and the second criteria, and the processsor also being configured to determine whether the second router is a primary router, wherein the primary router serves a function of a standard router.

10. A system for determining a state of a processor comprising:

a processor being configured to provide a first criteria and receive a second criteria, wherein the first criteria is associated with a first router and the second criteria is associated with a second router;

the processor also being configured to compare the first criteria and the second criteria, and determine the first router is a primary router, wherein the primary router serves a function of a standard router; and

a memory coupled to the processor for providing instructions to the processor.

11. The system of claim 10, wherein the first criteria is a medium access control (MAC) address.

12. The system of claim 10, wherein the first router and the second router are coupled to each other in a network environment.

13. The system of claim 10, wherein the first router is a primary router if the first criteria meets a predetermined criteria better than the second criteria.

14. The system of claim 10, wherein the first router is a secondary router if the second criteria meets a predetermined criteria better than the first criteria.

15. The system of claim 10, wherein a frame is sent by the second router to the first router to indicate the second criteria.

16. A computer program product for determining a state of a, router comprising:

computer code providing a first criteria and a second criteria, wherein the first criteria is associated with a first router and the second criteria is associated with a second router, and wherein the first router and second router are coupled to each other;

computer code comparing the first criteria and the second criteria;

computer code determining whether the first router is a primary router, wherein the primary router serves a function of a standard router.

17. The computer program product of claim 16, 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.