Submarine cables: ask whether two connections share a failure path
Different suppliers may share a dependency
ITU describes submarine cables as critical communications infrastructure exposed to natural and human-caused disruptions. A business buying two internet services cannot establish independence merely from two supplier names. Ask which physical routes, landing facilities and upstream dependencies are shared where that information is available.
A dependency record for continuity planning
| Layer | Question |
|---|---|
| Access | Are the local entries and access networks distinct? |
| Upstream | Which routes or facilities are shared or undisclosed? |
| Power | Do both services depend on the same site power? |
| Services | Do identity, DNS and cloud applications still function? |
| Recovery | Who reports incidents and what restoration terms apply? |
| Test | Which bounded failover exercise is authorised and recorded? |
Treat undisclosed topology as unknown, not as proof of diversity. A contractual availability target also differs from a tested application recovery. Some dependencies may be outside the buyer’s visibility or control.
A fictional failover exercise
For a planned test, a fictional office disables one authorised test connection and checks whether a specified cloud workflow can resume on the other. Record the start time, failed steps and time of restored operation. Do not interrupt a production connection without a suitable change plan. A successful test under those conditions does not establish resilience to every cable incident or a regional power failure.
Do not predict a repair date from a headline
Repair and service restoration depend on the incident and available alternatives. Use current provider notices for an actual disruption. This worksheet identifies questions and an exercise scope; we have not mapped a reader’s routes, measured network availability or promised a recovery time.
Sources and scope
- ITU: submarine cable resilience — Infrastructure context and cooperation; not a route-specific availability guarantee.
Sources checked October 10, 2026. AI-assisted research and drafting. The examples, calculations and worksheets are Luminesca editorial work; they are not measured trials, first-hand reporting or an independent certification. Removed unsupported cable counts, blanket repair times and satellite comparisons. Report a specific correction with its source.