Incident report · 2026092801
Ulleung-Mainland 2 cable: endpoint unreachable from all probes, 28 Sep 2026
Resolved · 2h 29m
What we measured
| Cable | Ulleung-Mainland 2 |
| Segment | Almaty KZ → Hosan-ri |
| Detected | 2026-09-28 09:02 UTC |
| Resolved | 2026-09-28 11:31 UTC |
| Duration | 2h 29m |
| Observed latency | 320.4 ms |
| Severity | critical |
Who is affected
Countries where Ulleung-Mainland 2 comes ashore, how much of their submarine diversity this cable represents, and what our measurements into them show.
| Country | Dependence on this cable | Other submarine cables | What the measurements show |
|---|---|---|---|
| South Korea resilience index: 100 · resilient |
1 of 17 cables (6% of submarine diversity) | APCN-2, Asia Pacific Gateway (APG), Asia United Gateway East (AUG East) +13 more | no measurement today; median 96 ms over 30 days (11 routes) |
Dependence is structural (share of the country's submarine cables), not a traffic share: real traffic distribution across cables is not public.
Timeline
- Alert #211 improving: 1/3 consecutive OK
- Alert #211 improving: 2/3 consecutive OK
- Alert #211 resolved: RTT 320.37ms (baseline 0ms), 3 consecutive OK
Evidence
RIPE Atlas measurements behind this detection, verifiable independently:
Detection method
Latency is sampled continuously from our probe network. An alert opens when round-trip time to a monitored endpoint holds above its rolling baseline, and closes automatically once it returns. Full method is described on the methodology page.
How to cite
GeoCables (2026). Incident 2026092801: Ulleung-Mainland 2. https://geocables.com/incident/2026092801
Embed this map
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