1.解决不规则区域大都是网络割接造成的，不规则区域是指（远离和隔离骨干区域）
- 解决方法有三种： 1.OSPF 多进程双向重分布2.tunnel（隧道技术）3.永久虚电路（ virtual-link）
3.永久虚电路配置（附图，重要部分用彩色笔画出）,拓补图见最后
4如果不做任何配置，R5是收不到R4的路由的，做永久虚电路后出现关键自： Adjacency State FULL (Hello suppressed) ，重新建立邻接关系。
R1:
interface Loopback0
ip address 1.1.1.1 255.255.255.0
interface FastEthernet0/0
ip address 12.1.1.1 255.255.255.0
interface FastEthernet0/1
ip address 13.1.1.1 255.255.255.0
router ospf 20
router-id 1.1.1.1
area 2 virtual-link 3.3.3.3 指向对端路由器的router-id
network 12.1.1.0 0.0.0.255 area 0
network 13.1.1.0 0.0.0.255 area 2
R2
interface FastEthernet0/0
ip address 24.1.1.1 255.255.255.0
interface FastEthernet0/1
ip address 12.1.1.2 255.255.255.0
router ospf 20
router-id 2.2.2.2
network 12.1.1.0 0.0.0.255 area 0
network 24.1.1.0 0.0.0.255 area 1
R3
interface Loopback0
ip address 3.3.3.3 255.255.255.0
interface FastEthernet0/0
ip address 13.1.1.2 255.255.255.0
interface FastEthernet0/1
ip address 35.1.1.1 255.255.255.0
router ospf 20
router-id 3.3.3.3
area 2 virtual-link 1.1.1.1** 指向R1的router-id
network 13.1.1.0 0.0.0.255 area 2
network 35.1.1.0 0.0.0.255 area 3
R4
interface Loopback0
ip address 4.4.4.4 255.255.255.0
interface FastEthernet0/0
ip address 24.1.1.2 255.255.255.0
router ospf 20
router-id 4.4.4.4
log-adjacency-changes
network 24.1.1.0 0.0.0.255 area 1
R5
interface FastEthernet0/0
ip address 35.1.1.2 255.255.255.0
router ospf 20
router-id 5.5.5.5
network 5.5.5.0 0.0.0.255 area 3
network 35.1.1.0 0.0.0.255 area 3
[Meting]
[Music server="netease" id="126443" type="song"/]
[/Meting]