TECHNIQUE FOR DETERMINING WHETHER TO REESTABLISH FAST REROUTED PRIMARY TUNNELS BASED ON BACKUP TUNNEL PATH QUALITY FEEDBACK

• US 20120044801A1
• Filed: 11/01/2011
• Published: 02/23/2012
• Est. Priority Date: 02/03/2006
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Vasseur, Jean-Philippe, Lo, Alton, Charny, Anna
• Granted Patent: US 8,885,460 B2
• Time in Patent Office: Days
• US Class Current: 370/217
• CPC Class Codes: H04J 3/14 Monitoring arrangements for SDH/SONET rings H04J3/085
• CPC Class Codes: H04L 12/4633 Interconnection of networks using encapsulation techniques, e.g. tunneling
• CPC Class Codes: H04L 45/22 Alternate routing
• CPC Class Codes: H04L 45/28 using route fault recovery
• CPC Class Codes: H04L 45/50 using label swapping, e.g. multi-protocol label switch [MPLS]
• CPC Class Codes: H04L 45/60 Router architectures

Abstract

In one embodiment, a primary tunnel is established from a head-end node to a destination along a path including one or more protected network elements for which a fast reroute path is available to pass traffic around the one or more network elements in the event of their failure. A first path quality measures path quality prior to failure of the one or more protected network elements. A second path quality measures path quality subsequent to failure of the one or more protected network elements, while the fast reroute path is being used to pass traffic of the primary tunnel. A determination is made whether to reestablish the primary tunnel over a new path that does not include the one or more failed protected network elements, or to continue to utilize the path with the fast reroute path, in response to a difference between the first path quality and the second path quality.

Claims

1. A method comprising:

calculating, by a path computation element (PCE) that includes one or more processors, a path of a primary tunnel from a head-end node to a destination, the path including one or more protected network elements for which a fast reroute path is available, the fast reroute path beginning at a point of local repair (PLR) node along the path and extending to a remerge point along the path and arranged to, in the event of failure of the one or more network elements, pass traffic of the primary tunnel around the failed one or more network elements;

ascertaining a first path quality of the primary tunnel that measures path quality prior to failure of the one or more protected network elements while the fast reroute path is not being used to pass traffic of the primary tunnel;

ascertaining a second path quality of the primary tunnel that measures path quality subsequent to failure of the one or more protected network elements while the fast reroute path is being used to pass traffic of the primary tunnel; and

determining whether to reestablish the primary tunnel over a new path that does not include the one or more failed protected network elements, or to continue to utilize the path with the fast reroute path, in response to a difference between the first path quality and the second path quality.

2. The method of claim 1, wherein the ascertaining a first path quality and the ascertaining a second path quality comprises receiving one or more path quality notifications from the PLR node.

3. The method of claim 2, further comprising:

requesting notification of path quality from the PLR node.

4. The method of claim 2, wherein the one or more path quality notifications are one or more Resource ReSerVation Protocol (RSVP) Traffic Engineering (TE) messages that store path quality as part of an LSP-ATTRIBUTE object.

5. The method of claim 1, wherein the fast reroute path is established as a zero-bandwidth path prior to failure of the one or more protected network elements.

6. The method of claim 1, further comprising:

receiving a notification of the failure of the one or more protected network elements.

7. The method of claim 6, further comprising:

waiting a certain amount of time after receiving notification of the failure of the one or more protected network elements; and

after the certain amount of time, causing the primary tunnel to be reestablished over a new path that does not include the one or more failed protected network elements.

8. The method of claim 1, further comprising:

establishing the primary tunnel over the path by the head-end node; and

reestablishing the primary tunnel over the new path that does not include the one or more failed protected network elements by the head-end node.

9. The method of claim 1, wherein the first path quality and the second path quality measure one or more of packet drop, jitter, cost, bandwidth or delay.

10. An apparatus comprising:

one or more network interfaces;

a processor coupled to the one or more network interfaces and configured to execute software processes; and

a memory adapted to store a traffic engineering (TE) process executable by the processor, the TE process configured to;

cause a primary tunnel to be established along a path to a destination, the path including one or more protected network elements for which a fast reroute path is available, the fast reroute path beginning at a point of local repair (PLR) node along the path and extending to a remerge point along the path and arranged to, in the event of failure of the one or more network elements, pass traffic of primary tunnel around the failed one or more network elements,

determine a first path quality of the primary tunnel that measures is path quality prior to failure of the one or more protected network elements while the fast reroute path is not being used to pass traffic of the primary tunnel,

determine a second path quality of the primary tunnel that measures path quality subsequent to failure of the one or more protected network elements while the fast reroute path is being used to pass traffic of the primary tunnel, and

cause the primary tunnel to be reestablished over a new path that does not include the one or more failed protected network elements, or to continue to utilize the path with the fast reroute path, in response to a difference between the first path quality and the second path quality.

11. The apparatus of claim 10, wherein the TE process is configured to determine the first path quality and determine the second path quality from one or more path quality notifications received from the PLR node on the one or more network interfaces.

12. The apparatus of claim 11, wherein the TE process is configured to:

request notification of path quality from the PLR node.

13. The apparatus of claim 11, wherein the one or more path quality notifications are one or more Resource ReSerVation Protocol (RSVP) Traffic Engineering (TE) messages that store path quality as part of an LSP-ATTRIBUTE object.

14. The apparatus of claim 11, wherein the fast reroute path is established as a zero-bandwidth path prior to failure of the one or more protected network elements.

15. The apparatus of claim 11, wherein the TE process is configured to:

determine the one or more protected network elements have failed from a received notification from the PLR.

16. The apparatus of claim 15, wherein the TE process is configured to:

wait a certain amount of time after receiving notification of the failure of the one or more protected network elements; and

after the certain amount of time, cause the primary tunnel to be reestabfished over a new path that does not include the one or more failed protected network elements.

17. The apparatus of claim 15, wherein the first path quality and the second path quality measure one or more of packet drop, jitter, cost, bandwidth or delay.

18. The apparatus of claim 11, wherein the apparatus comprises a head-end node of the primary tunnel.

19. The apparatus of claim 11, wherein the apparatus comprises a path computation element (PCE).

20. Software encoded on one or more non-transitory computer readable media that when execute is operable to:

establish a primary tunnel along a path to a destination, the path including one or more protected network elements for which a fast reroute path is available, the fast reroute path beginning at a point of local repair (PLR) node along the path and extending to a remerge point along the path and arranged to, in the event of failure of the one or more network elements, pass traffic of primary tunnel around the failed one or more network elements;

determine a first path quality of the primary tunnel that measures path quality prior to failure of the one or more protected network elements while the fast reroute path is not being used to pass traffic of the primary tunnel;

determine a second path quality of the primary tunnel that measures path quality subsequent to failure of the one or more protected network elements while the fast reroute path is being used to pass traffic of the primary tunnel; and

determining whether to reestablish the primary tunnel over a new path that does not include the one or more failed protected network elements, or continue to utilize the path with the fast reroute path for the primary tunnel, in response to a difference between the first path quality and the second path quality.