Line Flapping Detection in Optical Networks
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Solution Overview
Problem
Conventional optical networks fail to detect line flapping, where a line experiences intermittent failures or conditions, such as Loss of Frame (LOF) or Loss of Signal (LOS), for short durations, leading to missed alarms and potential degradation of system components like optical modules, which can go unnoticed by network operators.
Innovation Solution
A method and system for detecting line flapping by starting a timer upon detecting a line failure, counting subsequent failures, and raising an alarm if the threshold is exceeded, with configurable settings to enable or disable reporting, and correlating multiple defects as a single failure to generate an alarm, using a two-level hierarchical control mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional optical networks use standard alarm clearing mechanisms, then simple alarm handling is maintained, but line flapping conditions are not detected
Solution Approach 1:
The system performs preliminary actions by starting a timer when a line failure is detected and counting subsequent failures within a predetermined time window before raising the alarm. This preliminary timing and counting mechanism enables detection of line flapping conditions that would otherwise be missed by conventional immediate alarm clearing methods.
Solution Approach 2:
The system implements feedback by continuously monitoring the line state during the timer period and adjusting the alarm raising decision based on the counted failures. The feedback loop ensures that only genuine flapping conditions with sufficient failure frequency trigger alarms, while transient issues are filtered out.
2Measurement precision
If alarms are raised for every line failure, then all failures are detected, but intermittent failures cause excessive alarms
Solution Approach 1:
The system applies partial action by raising alarms only when a predetermined threshold of failures is counted within the timer period. This selective alarm raising filters out excessive alarm noise from transient failures while maintaining detection accuracy for genuine flapping conditions that exceed the threshold.
3Reliability
If the alarm clearing time is extended to capture flapping, then line flapping is detected, but normal operations are disrupted
Solution Approach 1:
The system implements dynamic alarm handling by adjusting the detection window based on the line state transitions. The timer and failure counter operate dynamically during flapping conditions while allowing normal operations to proceed uninterrupted, balancing detection capability with operational continuity.
Data Source
AI summary
The present disclosure provides line flapping detection systems and methods for optical networks using, for example, Synchronous Optical Network (SONET), Synchronous Digital Hierarchy (SDH), Optical Transport Network (OTN), and the like. Line flapping includes conditions, failures, etc. on a particular line going in and out of failure without raising an alarm or the like. The line flapping detection systems and methods provide configurable settings to set an alarm when it has been determined that a line is indeed flapping. First, there is a two level hierarchical control mechanism used to determine whether to report the alarm. Additionally, the line flapping detection systems and methods are configured to correlate events to count as single line failures instead of a plurality of distinct events.