Incident report · 2026092603
Ulleung-Mainland 2 cable: endpoint unreachable from all probes, 26 Sep 2026
Resolved · 2h 0m
What we measured
| Cable | Ulleung-Mainland 2 |
| Segment | Almaty KZ → Hosan-ri |
| Detected | 2026-09-26 21:02 UTC |
| Resolved | 2026-09-26 23:02 UTC |
| Duration | 2h 0m |
| Observed latency | 309.8 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 91 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 #209 improving: 1/3 consecutive OK
- Alert #209 improving: 2/3 consecutive OK
- Alert #209 resolved: RTT 309.76ms (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 2026092603: Ulleung-Mainland 2. https://geocables.com/incident/2026092603
Embed this map
<iframe src="https://geocables.com/embed.php?type=map&id=ulleung-mainland-2" width="640" height="420" frameborder="0" loading="lazy" style="border:0;border-radius:10px"></iframe>