What is the formula to calculate the OSPF interface cost?

The formula to calculate the OSPF (Open Shortest Path First) interface cost is based on the relationship between the reference bandwidth and the interface bandwidth. The correct formula, which is represented in the answer chosen, dictates that you divide the reference bandwidth by the interface bandwidth to arrive at the OSPF cost for that interface.

In OSPF, the default reference bandwidth is typically set at 100 Mbps (or 100,000 Kbps). By taking the reference bandwidth and dividing it by the actual bandwidth of the interface, one can calculate the cost of the interface. This means that a higher bandwidth interface will result in a lower cost, facilitating the selection of the most efficient routes within the OSPF routing protocol.

For instance, if you have an interface bandwidth of 1 Gbps (1,000 Mbps), the OSPF cost calculation would be:

Cost = 100 Mbps / 1,000 Mbps = 0.1

Because OSPF prefers paths with lower cost, this relationship ensures that faster interfaces are favored in route selections, thus optimizing network performance.

This understanding plays a crucial role in OSPF route calculations and influences how traffic is routed across the network. The other formulas suggested