OSPF peer initialization

FIGURE 5 . 1
OSPF peer initialization
The preceding states, not including the attempt state, are related to Hello packets,
while the following states are not. Additionally, the following states are not
seen entered into by two DROthers. The only pair of OSPF routers, of which neither
is a DR or BDR, that establish these states are those that are point-to-point
neighbors. Otherwise, one of the two routers will be a DR or BDR. This distinction
may help you bisect these eight items in your mind, helping to recall their
order or orientation when you need to.
Exchange
Routing information is exchanged using DD and LSR packets.
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Link-State Request (LSR) packets are sent to neighbors to request any new LSAs that
were found while in the Exchange state.
Full
All LSA information is synchronized among adjacent neighbors.
To gain a better understanding of how an adjacency is formed, let’s consider the formation
of an adjacency in a broadcast multi-access environment. Figure 5.1 displays a flowchart that
depicts each step of the initialization process. The process starts by sending out Hello packets.
Every listening router will then add the originating router to the neighbor database. The
responding routers will reply with all of their Hello information so that the originating router
can add them to its own neighbor table.