Hello packet has recently been received from the neighbor. In this state, communication between the two routers is bidirectional. ExStart The two neighbors are about to create an adjacency. The two neighbors are telling each other what they have in their topological databases. Loading The two neighbors are synchronizing their topological databases.
Various events cause a change of state.
For example, if a router receives a Hello packet from a neighbor that is down, the neighbor's state changes to init, and an inactivity timer is started. Refer to RFC 1583 for a complete description of the states and information on the events which cause state changes. A relationship formed between selected neighboring routers for the purpose of exchanging routing information. Not every pair of neighboring routers become adjacent. In particular, not every pair of routers will stay synchronized.