The OSPF protocol finds the most efficient route between two points. To find this route, it looks at factors such as interface link speed, the number of hops between points, and other metrics. By default, OSPF uses the actual link speed of a device to calculate the total cost of a route.
The following tables show the OSPF interface cost for different interface bandwidths. To help maximize efficiency on your network, you can manually specify a different cost. For example, if your Firebox supports higher link speeds than the router it connects to, you could manually specify a different cost.
Cost Table (FRR in Fireware v12.9 or Higher)
In Fireware v12.9 or higher, the reference bandwidth is 100 Gbps.
| Interface Type | Interface Bandwidth | OSPF Interface Cost |
|---|---|---|
| Ethernet | 100 Gbps | 1 |
| Ethernet | 10 Gbps | 10 |
| Ethernet | 1 Gbps | 100 |
| Ethernet | 100 Mbps | 1000 |
| Ethernet | 10 Mbps | 10,000 |
| Non-ethernet (BOVPN virtual interfaces and modems) | n/a | 10 |
Cost Table (Quagga in Fireware v12.8.x or Lower)
In Fireware v12.8.x or lower, the cost is always 10 in the following cases.
| Interface Type | Interface Bandwidth | OSPF Interface Cost |
|---|---|---|
| Ethernet | 1 Gbps | 10 |
| Ethernet | 100 Mbps | 10 |
| Ethernet | 10 Mbps | 10 |
| Non-ethernet (modems) | n/a | 10 |