Ethernet automatic protection switching

• US 6,766,482 B1
• Filed: 10/31/2001
• Issued: 07/20/2004
• Est. Priority Date: 10/31/2001
• Status: Active Grant

• Current Assignee: RPX Corporation
• Original Assignee: Extreme Networks, Inc.
• Inventors: Ragonese, Michelle M., Shah, Sunil P., Yip, Michael
• Primary Examiner(s): Ton, David
• Application Number:
  US09/999,796
• Time in Patent Office: 993 Days
• Field of Search: 370/223, 370/403, 370/224, 370/389, 370/222, 370/216, 398/9, 714/712, 714/717
• US Class Current: 714/717
• CPC Class Codes: H04L 12/437 Ring fault isolation or reconfiguration for SDH/SONET ring networks H04J3/085

Abstract

A method and apparatus is provided for automatic protection switching in a ring network by creating a protection domain having a control vlan and protected data vlans and designating a master node and transit nodes connected by a primary port and a secondary port. The master node blocks the secondary port for data vlan traffic until it detects a fault either by notice from a transit node or by polling. When a fault is detected, the master node unblocks the secondary port for data vlan traffic. When the fault is restored, the transit node temporarily blocks the restored port to data vlan traffic thereby preventing a loop. Each time the secondary port is blocked and unblocked, the forwarding databases on all the nodes are flushed.

Claims

1. A method for automatic protection switching in a ring network comprising:

creating an automatic protection switching domain having a control vlan and at least one data vlan;

detecting a fault in a ring network, the ring network having a master node connected to at least one transit node, each node linked to an adjacent node by at least one of a primary port or a secondary port, the fault indicating a failed link between adjacent nodes;

communicating the fault to the master node via the control vlan;

unblocking the master node'"'"'s secondary port to the at least one data vlan'"'"'s traffic;

setting a state of the ring network to failed; and

flushing a forwarding database on the master node and on the at least one transit node.

2. The method of claim 1, wherein communicating the fault to the master node via the control vlan comprises the at least one transit node sending a link down message to the master node via the control vlan, where the link down message indicates that the transit node has detected the failed link.

3. The method of claim 1, wherein detecting the fault comprises the master node polling the ring network to determine whether the ring network is complete.

4. The method of claim 3 wherein polling comprises the master node:

setting a fail-timer;

periodically sending a health-check message via the control vlan ; and

failing to receive the health-check message returned via the control vlan before the fail-timer expires.

5. The method of claim 4, further comprising the at least one transit node:

receiving the health-check message via the control vlan; and

forwarding the health-check message to the adjacent node prior to processing the health-check message by a central processing unit of the at least one transit node.

6. The method of claim 1 wherein detecting the fault in the ring network, communicating the fault to the master node, unblocking the master node'"'"'s secondary port, setting the state of the ring network to failed, and flushing the forwarding databases occurs in substantially less than one second.

7. The method of claim 1, further comprising:

detecting a fault restoration in the ring network;

blocking the master node'"'"'s secondary port to the at least one data vlan traffic;

setting the state of the ring network to complete; and

flushing the forwarding database on the master node and on the at least one transit node.

8. The method of claim 7 wherein detecting the fault restoration comprises the master node polling the ring network via the control vlan to determine that the ring network is complete.

9. The method of claim 8 wherein polling comprises the master node:

setting a fail-timer;

periodically sending a health-check message via the control vlan; and

receiving the health-check message returned via the control vlan before the fail-timer expires.

10. The method of claim 1, further comprising the at least one transit node:

detecting that the failed link connecting the transit node to the adjacent node has been restored;

temporarily blocking the port affected by the restored link to the at least one data vlan'"'"'s traffic;

saving an identity of the temporarily blocked port;

setting a state of the at least one transit node to pre-forwarding; and

setting a pre-forwarding timer.

11. The method of claim 10, further comprising the transit node:

determining that the state of the ring network is complete;

determining that the state of the transit node is pre-forwarding; and

unblocking the temporarily blocked port indicated in the saved identity.

12. The method of claim 11, wherein determining that the state of the ring network is complete comprises receiving a health-check message from the master node.

13. The method of claim 11, wherein determining that the state of the ring network is complete comprises the pre-forwarding timer expiring.

14. A machine accessible medium having content to cause a computer to perform a method for automatic protection switching in a ring network comprising:

creating an automatic protection switching domain having a control vlan and at least one data vlan;

detecting a fault in a ring network, the ring network having a master node connected to at least one transit node, each node linked to an adjacent node by at least one of a primary port or a secondary port, the fault indicating a failed link between adjacent nodes;

communicating the fault to the master node via the control vlan;

unblocking the master node'"'"'s secondary port to the at least one data vlan'"'"'s traffic;

setting a state of the ring network to failed; and

flushing a forwarding database on the master node and on the at least one transit node.

15. The machine accessible medium of claim 14, wherein communicating the fault to the master node via the control vlan comprises the at least one transit node sending a link down message to the master node via the control vlan, where the link down message indicates that the transit node has detected the failed link.

16. The machine accessible medium of claim 14, wherein detecting the fault comprises the master node polling the ring network to determine whether the ring network is complete.

17. The machine accessible medium of claim 16, wherein polling comprises the master node:

setting a fail-timer;

periodically sending a health-check message via the control vlan ; and

failing to receive the health-check message returned via the control vlan before the fail-timer expires.

18. The machine accessible medium of claim 17, further comprising the at least one transit node:

receiving the health-check message via the control vlan; and

forwarding the health-check message to the adjacent node prior to processing the health-check message by a central processing unit of the at least one transit node.

19. The machine accessible medium of claim 14 wherein detecting the fault in the ring network, communicating the fault to the master node, unblocking the master node'"'"'s secondary port, setting the state of the ring network to failed, and flushing the forwarding databases occurs in substantially less than one second.

20. The machine accessible medium of claim 14, further comprising:

detecting a fault restoration in the ring network;

blocking the master node'"'"'s secondary port to the at least one data vlan traffic;

setting the state of the ring network to complete; and

flushing the forwarding database on the master node and on the at least one transit node.

21. The machine accessible medium of claim 20, wherein detecting the fault restoration comprises the master node polling the ring network via the control vlan to determine that the ring network is complete.

22. The machine accessible medium of claim 21, wherein polling comprises the master node:

setting a fail-timer;

periodically sending a health-check message via the control vlan ; and

receiving the health-check message returned via the control vlan before the fail-timer expires.

23. The machine accessible medium of claim 14, further comprising the at least one transit node:

detecting that the failed link connecting the transit node to the adjacent node has been restored;

temporarily blocking the port affected by the restored link to the at least one data vlan'"'"'s traffic;

saving an identity of the temporarily blocked port;

setting a state of the at least one transit node to pre-forwarding; and

setting a pre-forwarding timer.

24. The machine accessible medium of claim 23, further comprising the transit node:

determining that the state of the ring network is complete;

determining that the state of the transit node is pre-forwarding; and

unblocking the temporarily blocked port indicated in the saved identity.

25. The machine accessible medium of claim 24, wherein determining that the state of the ring network is complete comprises receiving a health-check message from the master node.

26. The machine accessible medium of claim 24, wherein determining that the state of the ring network is complete comprises the pre-forwarding timer expiring.