What is the immediate action taken by an OSPF-enabled router after establishing an adjacency?

When an OSPF-enabled router establishes an adjacency with another OSPF router, the immediate action taken is to exchange link-state advertisements (LSAs). This is a crucial step in the OSPF routing process, allowing routers to share information about the state of their interfaces and networks.

Once two routers have completed the initial phases of the OSPF neighbor discovery process, including sending and receiving "Hello" packets to establish and verify adjacencies, they move on to an exchange of LSAs. During this exchange, routers share detailed topology information about the OSPF area they belong to. This information is critical for creating a complete and accurate link-state database, which is fundamental for OSPF's operation.

By exchanging LSAs, routers can then independently calculate the shortest path to each destination in the network using the Dijkstra algorithm, allowing them to update their routing tables accordingly. This process ensures that all routers have a synchronized view of the network topology and can make efficient routing decisions based on that information.

In summary, exchanging LSAs is the immediate action taken by OSPF routers post-adjacency, as it facilitates the necessary data sharing for effective routing within the OSPF domain.