Which OSPF Message Type sends a summary of link states?

The message type used to send a summary of link states in OSPF is the Database Description (DBD) message. DBD messages play a crucial role in the process of exchanging link-state information between OSPF routers. These messages contain an abbreviated list of the contents of the link-state database (LSDB), which allows routers to quickly identify which link-state advertisements (LSAs) they already have and which ones they need to acquire.

When a router receives a DBD message, it can determine whether it has all the necessary LSAs by comparing the summary provided in the DBD against its own LSDB. If a router finds that it is missing some LSAs, it will respond with a Link-State Request (LSR) to request those specific LSAs. This interaction minimizes the amount of data that needs to be sent, optimizing the efficiency of the OSPF routing protocol during database synchronization.

Understanding the function of DBD messages is fundamental to grasping how OSPF operates, as it forms the basis for the dissemination of routing information and supports the development of a complete and accurate topology map of the network within the OSPF area.