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