Method for computing a backup path for protecting a working path in a data transport network

• US 20040153496A1
• Filed: 01/31/2003
• Published: 08/05/2004
• Est. Priority Date: 01/31/2003
• Status: Abandoned Application

• Current Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Smith, Peter Ashwood, Shields, James A., DeBoer, Evert
• Application Number:
  US10/355,211
• Publication Number:
  US 20040153496A1
• Time in Patent Office: Days
• US Class Current: 709/201
• CPC Class Codes: H04L 45/22 Alternate routing
• CPC Class Codes: H04L 45/28 using route fault recovery
• CPC Class Codes: H04L 47/15 in relation to multipoint traffic arrangements for broadcast or multicast in data networks H04L12/18
• CPC Class Codes: H04L 47/70 Admission control; Resource allocation
• CPC Class Codes: H04L 47/728 for backup paths
• CPC Class Codes: H04L 47/746 Reaction triggered by a failure

Abstract

A method for computing a backup path for protecting a first working path in a data transport network that includes a plurality of working paths. The method includes determining a route of the backup path by selecting individual backup path segments from a set of possible segments in the data transport network. In the case of a segment that is shared between the first working path and one or more other working paths, the selection process takes into account the existence of a potential point of failure common to the working paths sharing the segment.

Claims

1. ) A method for computing a backup path for protecting a first working path in a data transport network that includes a plurality of working paths, the method comprising:

a) determining a backup path through the data transport network by selecting segments of the backup path from a set of available segments in the data transport network, where at least one of the selected segments is a shared segment part of a backup path protecting a second working path other than the first working path;

b) the selecting of the shared segment including determining if the first and second working paths have a common potential point of failure.

2. ) A method as defined in claim 1, wherein the point of failure includes a component of the data transport network conveying data.

3. ) A method as defined in claim 2, wherein at least one of the selected segments is for protection of the first working path but not for the protection of the second working path.

4. ) A method as defined in claim 3, wherein the first working path and the second working path have different endpoints.

5. ) A method as defined in claim 4, including selecting a given segment from the set of available segments in the data transport network as part of the backup path if working paths sharing the given segment are free of a common potential point of failure.

6. ) A method as defined in claim 4, wherein if the first and second working paths include a common potential point of failure, the selecting includes assessing a probability of failure at the common potential point of failure.

7. ) A method for computing a backup path for protecting a first working path in a data transport network that includes a plurality of working paths, the method comprising:

a) computing a tentative backup path through the data transport network the tentative backup path including a plurality of segments;

b) ascertaining for one or more segments if the segment is shared by working paths having a common potential point of failure.

8. ) A method as defined in claim 7, wherein the point of failure includes a component of the data transport network conveying data.

9. ) A method as defined in claim 8, wherein if a segment is identified in the tentative backup path as shared by working paths having a common potential point of failure, the method includes computing a new tentative backup path.

10. ) A method as defined in claim 9, wherein the method includes ascertaining for each segment of the new tentative backup path if the segment is shared by working paths having a common potential point of failure.

11. ) A method as defined in claim 10, wherein if no segment is found in the new tentative backup path that is shared by working paths having a common potential point of failure, implementing the backup path.

12. ) A computer readable storage medium containing a program element for execution by a computer to implement a method for computing a backup path for protecting a first working path in a data transport network that includes a plurality of working paths, the method comprising:

a) determining a backup path through the data transport network by selecting segments of the backup path from a set of available segments in the data transport network, where at least one of the selected segments is a shared segment part of a backup path protecting a second working path other than the first working path;

b) the selecting of the shared segment including determining if the first and second working paths have a common potential point of failure.

13. ) A computer readable storage medium as defined in claim 12, wherein the point of failure includes a component of the data transport network conveying data.

14. ) A computer readable storage medium as defined in claim 13, wherein at least one of the selected segments is for protection of the first working path but not for the protection of the second working path.

15. ) A computer readable storage medium as defined in claim 14, wherein the first working path and the second working path have different endpoints.

16. ) A computer readable storage medium as defined in claim 15, including selecting a given segment from the set of available segments in the data transport network as part of the backup path if working paths sharing the given segment are free of a common potential point of failure.

17. ) A computer readable storage medium as defined in claim 16, wherein if the first and second working paths include a common potential point of failure, the selecting includes assessing a probability of failure at the common potential point of failure.

18. ) A computer readable storage medium as defined in claim 16, including:

a) computing a tentative backup path including a plurality of segments;

b) ascertaining for each segment if the segment is shared by working paths having a common potential point of failure.

19. ) A computer readable storage medium as defined in claim 18, wherein if a segment is identified in the tentative backup path shared by working paths having a common potential point of failure, the method includes computing a new tentative backup path.

20. ) A computer readable storage medium as defined in claim 19, wherein the method includes ascertaining for each segment of the new tentative backup path if the segment if the segment is shared by working paths having a common potential point of failure.

21. ) A computer readable storage medium as defined in claim 20, wherein if no segment is found in the new tentative backup path that is shared by working paths having a common potential point of failure, implementing the backup path.