这个实验本人用的小凡做的 拓扑图就不给出了

Router1 F0/0 <----> Router2 F0/0

Router2 F0/1 <----> Router3 F0/1
Router3 F0/2 <----> Router4 F0/2
host R1
inte f0/0
no sw
ip add 192.168.1.1 255.255.255.0
router ospf 10
net 192.168.1.0 0.0.0.255 area 0
host R2
inte f0/0
no sw
ip add 192.168.1.2 255.255.255.0
inte f0/1
no sw
ip add 192.168.2.2 255.255.255.0
inte loop 0
ip add 2.2.2.2 255.0.0.0
router ospf 20
net 192.168.1.0 0.0.0.255 area 0
net 192.168.2.0 0.0.0.255 area 1
do show ip route
area 1  virtual-link  3.3.3.3
host R3
inte loop 0
ip add 3.3.3.3 255.0.0.0
inte f0/1
no sw
ip add 192.168.2.3 255.255.255.0
inte f0/2
no sw
ip add 192.168.3.3 255.255.255.0
router ospf 30
net 192.168.2.0 0.0.0.255 area 1
net 192.168.3.0 0.0.0.255 area 3
do show ip route
area 1  virtual-link  2.2.2.2
host R4
inte f0/2
no sw
ip add 192.168.3.4 255.255.255.0
router ospf 40
net 192.168.3.0 0.0.0.255 area 3