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PASSEDinfrastructure / fiber_optic_cable_cut
Fiber Optic Cable Cut — Dark Fiber Link Down
A construction crew accidentally cuts the dark fiber connecting two office buildings, severing all network connectivity between the primary data center and the disaster recovery site, including storage replication.
Pattern
NIC_ERRORS
Severity
CRITICAL
Confidence
95%
Remediation
Remote Hands
Test Results
| Metric | Expected | Actual | Result |
|---|---|---|---|
| Pattern Recognition | NIC_ERRORS | NIC_ERRORS | |
| Severity Assessment | CRITICAL | CRITICAL | |
| Incident Correlation | Yes | 35 linked | |
| Cascade Escalation | Yes | Yes | |
| Remediation | — | Remote Hands — Corax contacts on-site support via call, email, or API |
Scenario Conditions
Dark fiber pair between Building A (primary DC) and Building B (DR site). Construction crew severed both fiber strands. No diverse fiber path. All inter-building traffic: down. Storage replication, VM migration, and traffic affected.
Injected Error Messages (3)
dark fiber link failure between Building A and Building B — both fiber strands showing loss of light on optical transceivers, optical power level: -40dBm (threshold: -28dBm), network interface status: down, fiber patch panel A port 1-2 showing no signal, suspected physical fiber cut in underground conduit between buildings, all inter-building network links: down
DR site completely unreachable from primary data center — all network paths between Building A and Building B traverse severed dark fiber, no diverse fiber route available, DR site hosts, storage arrays, and network equipment all inaccessible, inter-site routing adjacency down, inter-building VLAN trunks: down, 200 users in Building B also isolated from primary services
storage replication to DR site halted — synchronous replication between primary SAN and DR SAN broken after fiber cut, replication RPO gap growing, primary storage continuing to serve I/O but all writes not replicated, replication queue filling on primary array, inter-site storage fabric completely disconnected, replication partner status: unreachable
Neural Engine Root Cause Analysis
Physical dark fiber infrastructure failure between Building A and Building B, with both fiber strands experiencing complete light loss. Optical power readings of -40dBm are significantly below the -28dBm threshold, indicating a physical break in the fiber optic cable, most likely in the underground conduit between buildings. This represents a catastrophic failure of the primary inter-building connectivity infrastructure, causing cascading network outages affecting 14 related systems.
Remediation Plan
1. Immediately activate backup connectivity (wireless bridge, temporary fiber, or alternate routing) if available. 2. Contact fiber optic repair contractor for emergency service. 3. Use Optical Time Domain Reflectometer (OTDR) to pinpoint exact location of fiber break in underground conduit. 4. Coordinate with facilities team to access underground conduit and assess damage extent. 5. Perform emergency fiber splice repair or full cable replacement as needed. 6. Test optical power levels and signal integrity before restoring service. 7. Implement redundant fiber paths to prevent future single points of failure.
Tested: 2026-03-30Monitors: 3 | Incidents: 3Test ID: cmncka0hj07w8obqee16tjeeg