This is the issue that we face some time & really it get hard or will take the entire day to resolve the issue ...
Let us see the most common reason that Why OSPF Neighbor Stuck in Exstart/ Exchange state.
What happen exactly in Exstart/ Exchange State ?
OSPF neighboring routers establish the relation & move forward ... In this state, the neighboring routers establish a master/slave relationship and determine the initial database descriptor (DBD) sequence number to use while exchanging DBD packets. Once
Now below are the reason that why the neighbor stuck in exstart/ exchange state
1] MTU Mismatch
2] Same router ID on both router.