Hello protocol to acquire neighbors . Neighbors are routers with interfaces to a common network. The router sends hello packets to its neighbors and receives their hello packets. In addition to helping acquire neighbors, hello packets also act as keepalives to let routers know that other routers are still functional. The designated router is responsible, among other things, for generating LSAs for the entire multiaccess network.
Designated routers allow a reduction in network traffic and in the size of the topological database.
When the link state databases of two neighboring routers are synchronized, the routers are said to be adjacent . On multiaccess networks, the designated router determines which routers should become adjacent. Topological databases are synchronized between pairs of adjacent routers. Adjacencies control the distribution of routing protocol packets. These packets are sent and received only on adjacencies.