Network & Infrastructure / OSPF & Underlay Convergence
LSA storms caused by one unstable interface
A widespread OSPF CPU alarm follows an intermittent link at the edge. Many routers show symptoms even though only one originator repeatedly changes its topology advertisement.
Environment and inputs: OSPFv2 IPv4 underlays, with OSPFv3 explicitly identified where used; timers and diagnostics vary by platform. Diagnostic/design example; not tested on production equipment.
Collect the evidence
Group LSA changes by advertising router, type and sequence over time. Correlate the highest-change origin with interface events, optics errors and adjacency resets rather than counting only total LSAs.
Explain the result
Flooding distributes an originator's instability across the area. High database activity on a core router can therefore be a propagated symptom rather than a local hardware fault.
Plan the fix
Contain or repair the unstable dependency using the approved redundancy plan. Review LSA generation and SPF throttling only after identifying the event source and supported platform limits.
Check the result and rollback
Verify reduced sequence churn, stable neighbor state and recovered CPU while checking redundant paths. Revert containment if it partitions a required area or shifts loss onto another bottleneck.