In a point-to-point link with two OSPF-enabled routers, which router sends the DBD packets first?

In a point-to-point link with two OSPF-enabled routers, the router that sends the Database Description (DBD) packets first is the one with the highest router ID. In OSPF, the router ID is a unique identifier assigned to each router within an OSPF domain. When establishing an OSPF neighbor relationship, routers use the router ID as part of their election process.

During the OSPF adjacency formation phase, the routers send hello packets to discover each other. Once a neighbor relationship is established, the router with the higher router ID becomes the designated router (DR) if the network type allows for a DR/BDR election, although this is not strictly necessary for point-to-point links. Regardless, the OSPF protocol dictates that in the exchange of routing information—specifically when DBD packets are used—the router with the highest router ID initiates this exchange.

Choosing the highest router ID as the sender of the initial DBD packets ensures a consistent method for determining which router takes the lead in the communication process. As a result, this mechanism helps maintain stability and predictability in the routing environment, particularly during the initial stages of establishing routes between the two routers.

This behavior is fundamental to OSPF