How the Internet routed around Cable Damage in the Baltic Sea#

Alastair Strachan (RIPE NCC)

• Why: Submarine cable cuts (several in the Baltic recently under suspicious circumstances) are the canonical physical-layer WAN failure. This talk uses actual measurement data to show what happens to latency, loss, and routing when a regional cable plant degrades — evidence rather than folklore about redundancy.
• What: An analysis of the impact of outages affecting the BSC East-West and C-LION1 cables, using RIPE Atlas measurements to track latency shifts, packet loss, and rerouting before and after the incidents. The program page summary reports the headline finding: only minor latency increases were observed, with inter-domain and intra-domain rerouting maintaining connectivity with minimal disruption.
• How: RIPE Atlas probe meshes provide continuous latency/loss time series across affected paths; changes around the incident window reveal which traffic moved, where it moved to, and how quickly.
• Where applicable: The specific event is Baltic-regional, but the methodology (Atlas-based before/after analysis of physical failures) is reusable by any operator for their own resilience validation, and the conclusion — meshed redundancy absorbs single/few cable failures — transfers to DC/WAN interconnect design generally.