Intelligent alarm filtering in a telecommunications network

• US 6,239,699 B1
• Filed: 03/03/1999
• Issued: 05/29/2001
• Est. Priority Date: 03/03/1999
• Status: Expired due to Term

• Current Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Ronnen, U. George
• Primary Examiner(s): Crosland, Donnie L.
• Application Number:
  US09/261,808
• Time in Patent Office: 818 Days
• Field of Search: 340/517, 340/511, 340/507, 340/825.16, 340/506, 340/519, 455/423, 455/9, 455/67.1, 379/1, 379/2, 379/26, 359/110, 370/241, 370/242
• US Class Current: 340/517
• CPC Class Codes: H04L 41/0622 based on time
• CPC Class Codes: H04Q 2213/13106 Microprocessor, CPU
• CPC Class Codes: H04Q 2213/13163 Fault alarm
• CPC Class Codes: H04Q 2213/13213 Counting, timing circuits
• CPC Class Codes: H04Q 2213/13367 Hierarchical multiplexing, add-drop multiplexing
• CPC Class Codes: H04Q 3/0075 Fault management techniques

Abstract

Redundant alarm messages generated by a plurality of Network Elements (NEs) in a Synchronous Optical Network (SONET) or Synchronous Digital Hierarchy (SDH) subnetwork are suppressed by a filter incorporated within a Subnetwork Controller (SBNC). In an illustrative embodiment of the invention, the SBNC filter collects and logs all alarm messages reported by the subnetwork NEs during a correlation period. After the period is completed, the filter determines whether at least one alarm that was reported during the period directly indicates a failure within the subnetwork and, if so, suppresses all other alarms arriving during the period that indicate conditions symptomatic of this failure. The correlation period persists for no longer than a maximum specified time period, and only so long as alarm messages continue to be reported during the interval.

Claims

1. A method for filtering alarms generated in a telecommunications network, said method comprising the steps of:

detecting initially the arrival of a directly detected failure condition alarm or a symptomatic condition alarm;

collecting and storing alarms generated within the network for a prescribed time period after the initial alarm detection; and

reporting at the conclusion of the prescribed time period all stored alarms other than symptomatic condition alarms originating on ports connected to links fully terminated within the network.

2. The method of claim 1, wherein each directly detected failure condition alarm is selected from the group consisting of loss of signal, loss of frame, out of frame, loss of pointer, signal label mismatch, synchronization failure, data communications channel failure, protection switching failure and equipment failure alarms.

3. The method of claim 1, wherein each symptomatic condition alarm is selected from the group consisting of alarm indication signal, remote failure indication, performance monitoring threshold crossing alert and successful protection switching completion alarms.

4. The method of claim 1, wherein the prescribed time interval is a correlation interval.

5. A method for filtering alarms generated in a telecommunications network, said method comprising the steps of:

collecting and storing alarms generated within the network for a prescribed time period;

when at least one of the stored alarms represents a directly detected equipment failure condition, suppressing each symptomatic condition alarm that originated at a port connected to a link fully terminated within the network; and

when at least one of the stored alarms represents a directly detected failure condition and none of the stored alarms represents a directly detected equipment failure condition, suppressing each symptomatic condition alarm that originated at a port connected to a link fully terminated within the network, when said symptomatic condition alarm is at a lower signal level than said at least one directly detected failure condition alarm.

6. The method of claim 5, further comprising the step of reporting all alarms stored within the prescribed time period that are not suppressed.

7. The method of claim 5, wherein each directly detected failure condition alarm is selected from the group consisting of loss of signal, loss of frame, out of frame, loss of pointer, signal label mismatch, synchronization failure, data communications channel failure, protection switching failure and equipment failure alarms.

8. The method of claim 5, wherein each symptomatic condition alarm is selected from the group consisting of alarm indication signal, remote failure indication, performance monitoring threshold crossing alert and successful protection switching completion alarms.

9. The method of claim 5, wherein the prescribed time period is a correlation period.

10. A method for establishing a period for correlating alarms detected within a telecommunications network, said method comprising the steps of:

initiating the correlation period with the detection of a first alarm;

detecting alarms generated subsequent to said first alarm over a first prescribed incremental time interval; and

accumulating the first prescribed time interval and subsequent prescribed incremental time intervals to define the correlation period, so long as one or more alarms are detected during each of said prescribed time intervals and a predefined maximum correlation period is not exceeded by the accumulated intervals.

11. The method of claim 10, wherein each detected alarm represents either a directly detected failure condition or a symptomatic condition.

12. A system for filtering alarms generated in a telecommunications network, said system comprising:

a network controller interconnected with one or more elements in the network,

wherein said network controller receives and stores alarms generated by said one or more network elements for a prescribed time period; and

an alarm filter, wherein said alarm filter is responsive to the network controller for determining whether at least one of the stored alarms is of a first type; and

when at least one of the stored alarms is of said first alarm type, selectively suppressing each stored alarm of a second alarm type,

wherein said second alarm type includes alarms originating at ports connected to links fully terminated within the network that indicate symptomatic conditions.

13. The system of claim 12, wherein said first alarm type includes alarms for directly detected failure conditions.

14. The system of claim 12, wherein said filter further comprises means for reporting all alarms stored within the prescribed time period that are not suppressed.

15. The system of claim 12, wherein the prescribed time period is a correlation period.

16. A method for filtering alarms generated in a telecommunications network, said method comprising the steps of:

collecting and storing alarms generated within the network for a prescribed time period; and

when at least one of the stored alarms is of a first alarm type, selectively suppressing each stored alarm of a second alarm type,

wherein said second alarm type includes alarms originating at ports connected to links fully terminated within the network that indicate symptomatic conditions.

17. The method of claim 16, wherein said first alarm type includes alarms for directly detected failure conditions.

18. The method of claim 17, wherein each directly detected failure condition alarm is selected from the group consisting of loss of signal, loss of frame, out of frame, loss of pointer, signal label mismatch, synchronization failure, data communications channel failure, protection switching failure and equipment failure alarms.

19. The method of claim 16, wherein each symptomatic condition alarm is selected from the group consisting of alarm indication signal, remote failure indication, performance monitoring threshold crossing alert and successful protection switching completion alarms.

20. The method of claim 16, further comprising the step of reporting all alarms stored within the prescribed time period that are not selectively suppressed.

21. The method of claim 16, wherein the prescribed time period is a correlation period.