What Happens When Undersea Internet Cables Are Cut? #balticsea #cableoutages

Why It Matters

Understanding how undersea cable outages affect latency and routing helps telecom operators and businesses design more robust networks, while informing risk assessments and investment in redundancy infrastructure.

Key Takeaways

• Baltic Sea cable outages caused measurable latency spikes across routes
• No significant packet loss observed during the undersea cable failures
• RIPE Atlas mesh revealed 20‑30% of paths affected temporarily
• Rerouting occurred via BGP, intra‑domain, and circuit‑level adjustments
• Resilience varies; African landslide event showed high packet loss

Summary

The video examines a series of undersea cable failures in the Baltic Sea between November and January, using RIPE Atlas measurements to quantify their impact on internet performance. By mapping latency and traceroute data from over 800 anchor nodes, the presenters illustrate how the network responded when key east‑west cables were damaged and subsequently repaired.

Analysis of the RIPE Atlas data shows a clear latency increase on roughly 20‑30% of affected paths, while packet loss remained negligible during the Baltic incidents. Visualizations highlight step‑wise latency spikes coinciding with outage events and a gradual return to baseline after repairs, suggesting traffic was successfully rerouted through alternative routes.

The discussion references a retired Navy captain’s briefing on cable vulnerability, repair‑ship announcements, and contrasts the Baltic case with a more severe African submarine landslide that caused 40‑60% packet loss. The presenters identify three rerouting mechanisms—inter‑domain (BGP), intra‑domain, and circuit‑level—observed across the events.

These findings underscore the internet’s resilience in well‑instrumented regions but also reveal limits when measurement infrastructure is compromised. Expanding RIPE Atlas anchor diversity, especially at cable landing sites, is recommended to improve real‑time monitoring and inform operators, insurers, and policymakers about redundancy needs.

Original Description

RIPE Community Presentation #balticsea #cableoutages #internet

Set against the backdrop of the Baltic Sea cable incidents in late 2024 and early 2025, this talk shows how RIPE NCC used RIPE Atlas measurements to understand what happened after the damage.

It highlights a key takeaway: even when submarine cables were cut, Internet traffic was able to reroute and stay online. At the same time, it shows that this kind of resilience depends on strong built-in redundancy and continuous measurement, not luck.

00:00 Baltic Sea cable damage

04:16 BCS East West cable outage visualisation

07:55 Sum up

08:25 Power outage

09:40 Deeper dive

12:53 Conclusion

13:26 RIPE Atlas coverage