During the OSPF Exstart State, which router becomes the master?

In the OSPF (Open Shortest Path First) protocol, during the Exstart state, routers determine which will act as the master and which will be the slave for the purpose of exchanging database descriptions (DBD). The router that has the highest router ID assumes the role of the master. This is important because the master is responsible for controlling the sequence of the DBD packets exchanged between the routers.

The decision is made based on the OSPF router ID, which is a unique identifier for each OSPF router. By designating the router with the highest ID as the master, OSPF ensures a consistent mechanism for selecting a primary device that will control the initiation of the DBD exchange process. Additionally, this facilitates an organized and predictable sequence for the formation of the OSPF adjacency.

While factors such as the first DBD packet sent play a role in the state transition process, the selection of the master is strictly based on the router ID, reinforcing the significance of uniquely identifying routers in an OSPF network. This stable behavior aids in network reliability and predictability during OSPF communications.