How does OSPF determine the best path to a destination?

OSPF, or Open Shortest Path First, utilizes a cost metric based on the bandwidth of the links to determine the best path to a destination. Each interface on a router is assigned a cost, which is typically calculated using the formula: 100,000,000/bandwidth in bits per second. This means that higher bandwidth links have lower costs, leading OSPF to prefer paths that traverse faster interfaces.

When OSPF routers exchange link-state information, they construct a complete topological map of the network. They then employ the Dijkstra algorithm, also known as the Shortest Path First (SPF) algorithm, to compute the shortest path to each destination based on the accumulated costs of the links. As a result, OSPF is efficient in finding the optimal path, favoring routes that minimize the overall cost rather than simply counting the number of hops or prioritizing paths from routing tables.

This method ensures that OSPF not only considers the number of routers (or hops) but places a more significant emphasis on the performance characteristics of the connections in the network. Thus, the correct determination of the best path hinges primarily on the evaluation of the link costs assigned to each route according to their respective bandwidths.