我们知道ospf中有几种区域类型：stub ，totally stub ,nssa ,totally nssa.
下面分别讲一下各种区域类型对路由的改变，实验图如下:
按如图配置好相关接口和参数，配置好后，查看R6路由如下：
O IA 192.168.123.0/24 [110/20] via 192.168.36.3, 00:00:04, FastEthernet0/0
1.0.0.0/32 is subnetted, 1 subnets
O IA 1.1.1.1 [110/21] via 192.168.36.3, 00:00:04, FastEthernet0/0
2.0.0.0/32 is subnetted, 1 subnets
O IA 2.2.2.2 [110/21] via 192.168.36.3, 00:00:04, FastEthernet0/0
O IA 192.168.14.0/24 [110/30] via 192.168.36.3, 00:00:04, FastEthernet0/0
3.0.0.0/32 is subnetted, 1 subnets
O 3.3.3.3 [110/11] via 192.168.36.3, 00:00:04, FastEthernet0/0
O IA 192.168.25.0/24 [110/30] via 192.168.36.3, 00:00:05, FastEthernet0/0
4.0.0.0/32 is subnetted, 1 subnets
O IA 4.4.4.4 [110/31] via 192.168.36.3, 00:00:05, FastEthernet0/0
