4 ExStart (quasi-start) Status - When the router and its neighbors into ExStart state, conversation between them would characterized as an adjacent relationship, but this time the router has not yet become a full adjoining state. ExStart state using Type 2 database description (DBD, DataBase Description) packet established two routers negotiate Hello packets with the relationship between them who is "master", who is "from." (OSPF router ID with the highest router will win and become "master")
5 Exchange (switching) state - a state in exchange, their neighbor routers to send link status information to each other using the DBD type 2 packet, the router that is described in each their link state database. The router information they learn its existing link-state database for comparison and confirms that each individual DBD packet, if any router which receives the link information is not in the database, the request to its neighbor about the router complete and current information of the link. Complete routing information is exchanged in the "Loading (Load)" state.
6 Loading (loaded) state - after another through the respective description link state database, the router can request a more complete link state information of Type 3 request (LSR) packets. When a LSR receives a router, it will be updated with a link-state type 4 (LSU) response packets. These types of packets 4 containing LSU exact LSA, the LSA is a core link state type routing protocol, the type of the packet 4 by the LSU 5 LSack types of acknowledgment packet.
7 Full Adjacency (full abutment) state - after the end of the load state, the router into the next whole state. Each router maintains a list of adjacent routers, it is called adjacent database.
Link: https: //www.jianshu.com/p/e7fbc101856e
