Japan experienced a connectivity degradation on Tuesday, primarily affecting IPv4 network reachability. The disruption occurred in two phases between 14:20 and 16:30 UTC, with a total duration of approximately 2.2 hours. The event registered a severity score of 2,709, driven by a significant drop in the ping-slash24 signal.
Technical Details
The primary affected metric was ping-slash24, which measures ICMP reachability across IPv4 /24 network prefixes. Its severity score peaked at 1,708 during the first phase from 14:20 to 15:30 UTC, followed by a second phase scoring 1,002 from 15:50 to 16:30 UTC. The signal showed a 28% drop from its peak value during the observation window.
Other monitored signals showed minimal deviation. The Border Gateway Protocol (BGP) control plane, which tracks routing advertisement visibility, remained stable. The gtr-norm signal, a forecast deviation from expected traffic baselines, recorded an 80% drop from its peak, while the merit-nt backscatter measurement, an aggregate connectivity proxy, showed a 6% decline.
Reported Cause
The cause has not been publicly attributed.
Connectivity was reported restored by the end of the observation period.
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