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. You can set the interface cost manually to help maximize efficiency if, for example, your gigabyte-based firewall is connected to a 100M router. Use the numbers in this table to manually set the interface cost to a value different than the actual interface cost.

Interface Type Bandwidth in bits/second Bandwidth in bytes/second OSPF Interface Cost
Ethernet 1G 128M 1
Ethernet 100M 12.5M 10
Ethernet 10M 1.25M 100
Modem 2M 256K 500
Modem 1M 128K 1000
Modem 500K 62.5K 2000
Modem 250K 31.25K 4000
Modem 125K 15625 8000
Modem 62500 7812 16000
Serial 115200 14400 10850
Serial 57600 7200 21700
Serial 38400 4800 32550
Serial 19200 2400 61120
Serial 9600 1200 65535

See Also

About Open Shortest Path First (OSPF and OSPFv3) Protocol

OSPF Commands

OSPFv3 Commands