OSPF Interface Cost Table

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

See Also

About Open Shortest Path First (OSPF and OSPFv3) Protocol

OSPF Commands (FRR)

OSPF Commands (Quagga)