AR1:
Int lo 1
Ip add 1.1.1.1 24
Int g0/0/0
Ip add 12.1.1.1 24
?
Ospf 1 router-id 1.1.1.1
Area 0
Network 1.1.1.0 0.0.0.255
Network 12.1.1.0 0.0.0.255
AR2:
Int lo 1
Ip add 2.2.2.2 24
Int g0/0/1
Ip add 12.1.1.2 24
Int g0/0/0
Ip add 23.1.1.2 24
Ospf 1 router-id 2.2.2.2
Area 0
Network 2.2.2.0 0.0.0.255
Network 12.1.1.0 0.0.0.255
Network 23.1.1.0 0.0.0.255
AR3:
Int lo 1
Ip add 3.3.3.3 24
Int g0/0/1
Ip add 23.1.1.3 24
Ospf 1 router-id 3.3.3.3
Area 0
Network 3.3.3.0 0.0.0.255
Network 23.1.1.0 0.0.0.255
原文：https://www.cnblogs.com/hehuanling/p/10062486.html