Method and system for network wide fault isolation in an optical network

• US 20050099953A1
• Filed: 11/05/2004
• Published: 05/12/2005
• Est. Priority Date: 11/07/2003
• Status: Active Grant

• Current Assignee: WSOU Investments, LLC (WSOU Holdings, LLC)
• Original Assignee: Tropic Networks, Inc. (Nokia Corporation)
• Inventors: MacDonald, Roderick William
• Granted Patent: US 7,406,260 B2
• Time in Patent Office: Days
• US Class Current: 370/241
• CPC Class Codes: H04L 41/0631 using root cause analysis; using analysis of correlation between notifications, alarms or events based on decision criteria, e.g. hierarchy, tree or time analysis
• CPC Class Codes: H04L 41/0659 by isolating or reconfiguring faulty entities

Abstract

A method and system for network wide fault isolation in an optical network are described. A single fault in a network can produce a large number of alarms at different points in an optical network. The described method and system identify the root cause alarm while masking all correlated alarms. In the embodiment of the invention, the method and system are based on a wavelength tracker technology allowing identification and tracking of individual channels in the optical network.

Claims

1. A method for network wide fault isolation in an optical network having Optical Channel (OCh) paths, each OCh path comprising a sequence of ports, the method comprising the steps of:

identifying root cause alarms in the optical network; and

displaying said root cause alarms.

2. A method as claimed in claim 1, wherein the step of identifying the root cause alarms in the optical network comprises the steps of:

constructing a list of all affected OCh paths in the optical network; and

analyzing the OCh paths in said list.

3. A method as claimed in claim 2, wherein the step of analyzing the OCh paths in said list, comprises the steps of:

masking alarms in the OCh paths in transmit direction; and

masking alarms in the OCh paths in receive direction.

4. A method as claimed in claim 3, wherein the step of masking alarms in the OCh path in the transmit direction comprises the step of analyzing alarms at the ports on the OCh path in the transmit direction.

5. A method as claimed in claim 4, wherein the step of analyzing alarms comprises the steps of:

preparing a list of the alarms present at each port on the OCh path in the transmit direction;

determining if each alarm in the list is an OCh alarm or a port level alarm or a card level alarm; and

masking alarms in the downstream OCh path in the transmit direction that are

correlated with each alarm in the list.

6. A method as claimed in claim 5, wherein for a specific OCh path, OCh alarms can mask OCh alarms, port level alarms can mask port level alarms and OCh alarms and card level alarms can mask port level alarms and OCh alarms.

7. A method as claimed in claim 3, wherein the step of masking alarms in the OCh path in the receive direction comprises the step of analyzing alarms at the ports on the OCh path in the receive direction.

8. A method as claimed in claim 7, wherein the step of analyzing alarms comprises the steps of:

preparing a list of the alarms present at each port on the OCh path in the receive direction;

determining if each alarm in the list is an OCh alarm or a port level alarm or a card level alarm; and

masking alarms in the downstream OCh path in the receive direction that are correlated with each alarm in the list.

9. A method as claimed in claim 8, wherein for a specific OCh path, OCh alarms can mask OCh alarms, port level alarms can mask port level alarms and OCh alarms and card level alarms can mask port level alarms and OCh alarms.

10. A method as claimed in claim 1, wherein the step of displaying said root cause alarms comprises the step of displaying remaining unmasked alarms.

11. A method for network wide fault isolation in an optical network with an Element Management System (EMS), wherein the EMS has a view of a network topology and Wavelength Tracker data obtained by using Wavelength Tracker technology, the optical network contains Optical Channel (OCh) paths, each having a unique signature in a form of a low frequency dither tone modulation called Wavekey, generated by Wavelength Tracker, the method comprising the steps of:

identifying root cause alarms in the optical network; and

displaying said root cause alarms.

12. A method as claimed in claim 11, wherein the step of identifying the root cause alarms in the optical network with EMS comprises the step of masking non-root cause alarms in the OCh paths in the optical network.

13. A system for network wide fault isolation in an optical network, wherein the optical network contains OCh paths, each OCh path comprising a sequence of ports, the system comprising:

means for identifying root cause alarms in the optical network; and

a display unit for displaying said root cause alarms.

14. A system as claimed in claim 13, wherein the means for identifying the root cause alarms in the optical network comprises:

means for constructing a list of all affected OCh paths in the optical network; and

means for analyzing the OCh paths in said list.

15. A system as claimed in claim 14, wherein the means for analyzing the OCh paths in said list comprises:

means for masking alarms in the OCh path in transmit direction; and

means for masking alarms in the OCh path in receive direction.

16. A system as claimed in claim 15, wherein the means for masking alarms in the OCh path in the transmit direction comprises means for analyzing alarms at the ports on the OCh path in the transmit direction.

17. A system as claimed in claim 16, wherein the means for analyzing alarms in the transmit direction comprises:

means for preparing a list of the alarms present at each port on the OCh path in the transmit direction;

means for determining if each alarm in the list is an OCh alarm or a port level alarm or a card level alarm; and

means for masking alarms in the downstream OCh path in the transmit direction that are correlated with each alarm in the list.

18. A system as claimed in claim 17, wherein for a specific OCh path, OCh alarms can mask OCh alarms, port level alarms can mask port level alarms and OCh alarms and card level alarms can mask port level alarms and OCh alarms.

19. A system as claimed in claim 15, wherein the means for masking alarms in the OCh path in the receive direction comprises means for analyzing alarms in each port on the OCh path in the receive direction.

20. A system as claimed in claim 19, wherein the means for analyzing alarms comprises:

means for preparing a list of the alarms present at each port on the OCh path in the receive direction;

means for determining if each alarm in the list is an OCh alarm or a port level alarm or a card level alarm; and

means for masking alarms in the downstream OCh path in the receive direction that are correlated with each alarm in the list.

21. A system as claimed in claim 20, wherein for a specific OCh path, OCh alarms can mask OCh alarms, port level alarms can mask port level alarms and OCh alarms and card level alarms can mask port level alarms and OCh alarms.

22. A system as claimed in claim 13, wherein the display unit for displaying said root cause alarms comprises means for displaying remaining unmasked alarms.

23. A system for network wide fault isolation in an optical network with an Element Management System (EMS), wherein the EMS has a view of a network topology and Wavelength Tracker data obtained by using Wavelength Tracker technology, and the optical network contains Optical Channel (OCh) paths, each having a unique signature in a form of a low frequency dither tone modulation called Wavekey generated by Wavelength Tracker, the system comprising:

means for identifying root cause alarms in the optical network with EMS; and

a display unit for displaying said root cause alarms.

24. A system as claimed in claim 23, wherein the means for identifying root cause alarms in the optical network with EMS comprises means for masking non-root cause alarms in the OCh paths in the optical network.