What does OSPF use to prevent routing loops?

OSPF, or Open Shortest Path First, employs a link-state routing protocol design, which is fundamental in preventing routing loops. In a link-state routing protocol, each router maintains a map of the entire network topology, updated with information received from its neighbors through Link State Advertisements (LSAs). This comprehensive view allows OSPF routers to compute the best path to each destination using the Dijkstra algorithm, resulting in a loop-free environment.

By working with the complete network topology, OSPF routers can determine the optimal routing path without the ambiguity that might lead to loops, which is a significant risk in distance vector protocols. In contrast, distance vector protocols may rely on metrics such as hop count and have mechanisms like split horizon and poison reverse, but these do not offer the same level of accuracy and robustness in routing decisions as the link-state approach does.

Furthermore, link-state protocols like OSPF only send updates when there are changes in the network topology rather than periodic updates, which minimizes unnecessary information sharing and the probability of loops occurring. Thus, the utilization of a link-state routing mechanism is crucial in maintaining a stable and loop-free routing environment within OSPF networks.