What action does a router take when it receives a DBD packet during the Exchange State?

When a router receives a Database Description (DBD) packet during the Exchange State of the OSPF (Open Shortest Path First) protocol, it compares the contents of the DBD packet with its own Link-State Database (LSDB). The purpose of this comparison is to synchronize the two routers' databases regarding routing information.

The DBD packet contains summaries of the link-state information that the sender has. By comparing this information with its LSDB, the receiving router can determine which link-state information is missing or out-of-date. This sets the stage for further communication, as the router can then request any missing information from the sender via Link State Request packets. This step is crucial in the OSPF process as it ensures that both routers maintain an accurate and up-to-date view of the network topology, which is essential for making the best routing decisions.

The process of comparing the DBD contents is key to maintaining the efficiency and accuracy of the OSPF protocol, as it directly affects the routing tables and the overall network performance.