OSPF

Two versions, for IPv4 and IPv6
Uses multicast
Link State Protocol: routers learn about neigbors and the links to their neighbors
Dijkstra's shortest path algorithm is run on that data
Shortest path is put into the routing table (FIB)
Used to carry internal infrastructure prefixes.

$ ospfctl sh neigh
ID           Pri State        DeadTime Address      Iface     Uptime
192.0.2.26   1   FULL/OTHER   00:00:32 192.0.2.26   ix0       05w2d06h
192.0.2.22   1   FULL/DR      00:00:32 192.0.2.22   ix1       10w6d03h