Network & Infrastructure / OSPF & Underlay Convergence
Duplicate OSPF router IDs and self-originated LSA churn
Routes flap after a cloned router joins an underlay, even though addressing is unique. Reused router IDs can cause conflicting ownership of self-originated advertisements.
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
Record router IDs, LSA advertising-router fields, sequence changes and timestamps across neighbors. Compare configuration templates, restored backups and devices recently added to the same OSPF domain.
Explain the result
An OSPF router ID identifies an originator independently of interface addresses. Two devices claiming it can overwrite topology information or repeatedly react to apparent newer self-originated state.
Plan the fix
Assign a stable unique ID according to the network inventory. Follow the implementation's documented activation procedure, which may require a disruptive protocol restart.
Check the result and rollback
Check that churn stops, each LSA has one owner and routes remain stable through a controlled adjacency change. Restore the previous topology if a replacement ID collides elsewhere.