Segment-Based DWDM Lightpath Monitoring Using an Interval Type-2 Fuzzy Logic System and Temporal Stabilization

Optical protection switching on dynamic IS-IS and MPLS backbones can trigger adjacency resets, producing false positives and alarm flapping. This study designs a DWDM lightpath monitoring system using an Interval Type-2 Fuzzy Logic System (IT2FLS) as the alarm classifier, combined with a temporal stabilizer of debounce N=3 and hold-down H=3 to suppress false alarms. Data were collected through ICMP active probing from Customer Edge devices with strict path locking, yielding 736,764 samples from 34 lightpaths over 144 hours. The stabilizer reduced total alarm events from 6,333 to 2,313 (down 63.5%) and the false positive rate from 13.33 to 5.08 per hour (down 61.9%), with recall remaining high at 0.921 despite a decrease from 0.986 under raw conditions. The stabilizer effect was significant and consistent across the 34 segments (Wilcoxon signed-rank, p < 10⁻⁶). The system is proven to suppress false alarms without changing the total reported fault duration.