Network & Infrastructure / OSPF & Underlay Convergence
OSPF network-type mismatches and misleading neighbor visibility
A point-to-point side and a broadcast side can see hello traffic while failing to establish the expected usable topology. Neighbor visibility alone does not confirm matching link semantics.
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
Capture network type, hello/dead intervals, router priorities and represented topology on both endpoints. Compare the resulting router and network advertisements rather than inspecting only the neighbor summary.
Explain the result
Network type controls adjacency rules, election behavior and how the link is described in the database. Inconsistent assumptions can leave a partial or misleading control-plane picture.
Plan the fix
Select one network type appropriate to the actual link and apply a coordinated correction. Avoid changing timers independently as a substitute for fixing the underlying representation.
Check the result and rollback
Verify the expected adjacencies, link-state advertisements and routes from both routers. Revert if the change alters unrelated multiaccess relationships or produces transient loops beyond the maintenance plan.