OSPF - Router Discovery

Hello Packets sent all 10 seconds
sent via multicast
bidirectional communication enforced
a list of all routers from where a hello was received lately included in hello

Designated Router (DR)
only on broadcast networks
reduces the amount of packets sent
DR does flooding and retransmission on behalf of all other routers
Backup designated router in case DR fails
complex and error prone (imprecise RFC)