OSPF Path Analyzer
Calculate OSPF interface cost, inspect neighbour states and work through a shortest-path calculation on a simple link-state topology.
Interface cost
Common reference values
| Reference | Link | Raw cost |
|---|---|---|
| 100 Mbps | 1 Gbps | 0.1 |
| 100,000 Mbps | 10 Gbps | 10 |
| 100,000 Mbps | 1 Gbps | 100 |
| 100,000 Mbps | 100 Mbps | 1000 |
Many implementations store an integer OSPF cost. If the raw calculation is below 1, vendor behaviour and configuration determine the resulting cost; this calculator shows the arithmetic and flags sub-1 results.
Topology
Enter one bidirectional link per line as A-B=10. The value is the OSPF cost. Example: A-B=10, B-C=20, A-C=50.
SPF result
OSPF neighbour state
Engineering notes
OSPF is a link-state IGP. Routers form adjacencies, exchange LSAs, build a link-state database and run SPF to calculate paths. This tool models the core cost and SPF concepts; real deployments also depend on areas, area types, network types, summarisation, ECMP and implementation-specific defaults.