What is the OSPF cost of a 10Gig Ethernet interface with the default reference bandwidth?

The OSPF (Open Shortest Path First) cost for a particular interface is calculated based on the reference bandwidth and the interface's bandwidth. The default reference bandwidth used in OSPF is 100 Mbps. Therefore, when calculating the cost of an interface, the formula used is:

Cost = Reference Bandwidth / Interface Bandwidth

For a 10 Gigabit Ethernet interface, the bandwidth is 10,000 Mbps. Using the default reference bandwidth of 100 Mbps, the calculation for the OSPF cost becomes:

Cost = 100 Mbps / 10,000 Mbps = 0.01

To express this cost in whole numbers, OSPF typically does not use decimal values for cost calculations. The OSPF cost is rounded down to the nearest whole number, which results in a cost of 1 for a 10 Gigabit Ethernet interface when using the default reference bandwidth.

This understanding of OSPF costs highlights the fundamental principle that OSPF utilizes these values to determine the shortest path based on the lowest cost route. Thus, understanding how the interface speed relates to the OSPF cost is crucial for effective network design and routing decisions in OSPF environments.