In OSPF calculations, what is the resulting cost of an interface with a higher bandwidth?

In OSPF (Open Shortest Path First) calculations, the cost of an interface is determined inversely by its bandwidth. This means that higher bandwidth interfaces will have a lower OSPF cost. The formula used to calculate OSPF cost is based on the formula:

Cost = Reference Bandwidth / Interface Bandwidth

The reference bandwidth is typically set to 100 Mbps by default in OSPF configurations. Therefore, when you have an interface with a higher bandwidth (for instance, Gigabit Ethernet at 1000 Mbps), the division results in a smaller numerical value for cost.

For example, if the reference bandwidth is 100 Mbps and the interface bandwidth is 1000 Mbps, the calculation would yield a cost of 0.1. Conversely, if the interface had a bandwidth of 10 Mbps, the cost would be 10. Thus, as the bandwidth increases, the resulting cost decreases, leading to the conclusion that links with greater bandwidth are favored in OSPF path selection by having a lower cost assigned.

This principle is fundamental in OSPF network design and ensures that data is routed through the most efficient paths possible.