On an OSPF network, there are multiple types of packets, each with a different function.

Hello packets are the most basic and essential type of OSPF packets used for the following purposes:

Neighbor discovery – Routers use Hello packets to discover other OSPF routers on the same link.

Neighbor relationship establishment – When two routers exchange matching Hello packets, they move from the " Init " state to " 2-Way " and further into adjacency states.

Neighbor relationship maintenance – Hello packets are sent periodically to ensure that neighbors are still reachable. If Hello packets are missed within the dead interval, the neighbor is considered down.

Neighbor deletion is not a direct function of Hello packets. Neighbor deletion results indirectly from missed Hello packets.