What action is taken by an OSPF router when it receives a Link-State Update packet?

When an OSPF router receives a Link-State Update (LSU) packet, the most appropriate action is to generate a Link-State Request (LSR) to retrieve any missing Link-State Advertisements (LSAs) if needed. This process is crucial for maintaining accurate and up-to-date link-state databases across OSPF routers.

Upon receipt of the LSU packet, the router analyzes the LSAs included in that packet. If it finds that certain LSAs it expects to have are absent, it will create and send an LSR to its neighbor routers to request those specific LSAs. This ensures that the router has complete and synchronized information about the network topology, which is essential for making informed routing decisions.

Generatating an LSR facilitates proper database synchronization among OSPF routers. This step is critical because OSPF operates on the concept of a link-state database, in which every router maintains the same view of the network. Accurate LSAs are vital for recalculating the best paths and ensuring efficient routing.

The correct action taken in response to receiving an LSU acknowledges the need for proactive communication between OSPF routers to ensure data accuracy and completeness, reinforcing OSPF's design principle of maintaining a consistent view of the network.