ip add 1.1.1.1 255.255.255.0 int s1/2
ip add
12.1.1.1 255.255.255.0 no shu
ip ospf authentication
ip ospf authentication-key ccna
router os 110
net 1.1.1.1 0.255.255.255 a 0 net 12.1.1.1 0.255.255.255 a 0
R2：
Int l0
Ip add 2.2.2.2 255.255.255.0 Int s1/3
Ip add 12.1.1.2 255.255.255.0 No shu
Ip os authentication-key ccna
Int s1/2
Ip add 23.2.2.2 255.255.255.0