如图，Area 0 不连续，配置好各设备IP地址信息，和基本的动态路由协议信息，测试好互连地址可达。

查看各路由器路由表：

R1#show ip route
Gateway of last resort is not set

     172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
C       172.16.255.0/30 is directly connected, Serial0/0
O IA    172.16.255.4/30 [110/128] via 172.16.255.2, 00:01:14, Serial0/0
C       172.16.1.0/24 is directly connected, Loopback0

R1仅学习到去往Area 2的路由。

R2#show ip route
Gateway of last resort is not set

     172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
C       172.16.255.0/30 is directly connected, Serial0/0
C       172.16.255.4/30 is directly connected, Serial0/1
O       172.16.1.1/32 [110/65] via 172.16.255.1, 00:03:02, Serial0/0

R2仅学习到去往R1回环地址的路由。

R3#show ip route
Gateway of last resort is not set

     172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
C       172.16.255.4/30 is directly connected, Serial0/0
C       172.16.255.8/30 is directly connected, Serial0/1
O IA    172.16.16.1/32 [110/65] via 172.16.255.10, 00:02:20, Serial0/1

R3仅学习到去往R4回环地址的路由。

R4#show ip route
Gateway of last resort is not set

     172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
O IA    172.16.255.4/30 [110/128] via 172.16.255.9, 00:02:33, Serial0/0
C       172.16.255.8/30 is directly connected, Serial0/0
C       172.16.16.0/24 is directly connected, Loopback0

R4仅学习到去往Area 2的路由。

结果表明：任何一台路由器都不能完整地学习到网络中的路由信息，产生此问题的原因是：骨干区域被区域2分割，造成整个网络变成两个OSPFR的自治系统，所以相互之间都不能学习到完整的路由信息。

可以通过配置虚链路来解决骨干被分割的问题。

在R2和R3上按如下配置：

R2(config)#router ospf 1
R2(config-router)#area 2 virtual 172.16.255.9

----->area 2指出虚链路存在于区域2中，使用的是router-id
R2(config-router)#exit      配置到R3的路由器虚链路

R3(config)#router ospf 1
R3(config-router)#area 2 virtual 172.16.255.5

----->配置到R2的路由器虚链路
R3(config-router)#exit

再随意选择一台路由器查看路由表：

R1#show ip route
Gateway of last resort is not set

     172.16.0.0/16 is variably subnetted, 5 subnets, 3 masks
C       172.16.255.0/30 is directly connected, Serial0/0
O IA    172.16.255.4/30 [110/128] via 172.16.255.2, 00:05:50, Serial0/0
O       172.16.255.8/30 [110/192] via 172.16.255.2, 00:05:50, Serial0/0
O IA    172.16.16.1/32 [110/193] via 172.16.255.2, 00:05:50, Serial0/0
C       172.16.1.0/24 is directly connected, Loopback0

路由表已经完整。

测试：

R1#ping 172.16.16.1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.16.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 40/60/92 ms
R1#ping 172.16.255.9

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.255.9, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 12/53/108 ms
R1#ping 172.16.255.6

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.255.6, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 40/49/60 ms

往返可达。

此时，无法学习完整的路由问题已经被解决。OSPF Virtual Link 不仅可以解决普通区域与骨干区域非直接问题，还可以解决骨干被分割问题。但是，此类问题一般都是由于网络迁移或是本身设计问题所造成的。OSPF 的虚链路仅仅是一种网络过渡的解决方案。