How often must an OSPF router reflood an LSA it originates?

An OSPF (Open Shortest Path First) router must reflood an LSA (Link State Advertisement) it originates every 30 minutes. This periodic update is essential for maintaining the accuracy and timeliness of the OSPF routing information within the network.

The reason behind the 30-minute interval is to ensure that all routers in the OSPF area remain synchronized and have up-to-date information about the state of the network. If there are changes in the network topology, such as a link going down or coming up, the LSA must be propagated quickly to inform all neighbors and ensure efficient and accurate routing. Although LSAs are flooded immediately when a change occurs, the regular 30-minute reflooding acts as a safeguard to handle any cases where updates might not have been received due to transient issues.

Understanding this timing mechanism is crucial for network professionals as it affects OSPF convergence times and overall network stability.