CCIE-07-OSPF-TS

实验条件

网络拓朴

逻辑拓扑

实现目标

环境配置

在我的资源里可以下载（就在这篇文章的开头也可以下载）

开始Troubleshooting

整体排错的思路如下：

1. 检查所有的直连口是否双UP
2. 检查所有的IGP启动情况，邻居状态
3. 根据输出，调整路由参数
   检查所有的直连接口都正常启动。
   R22发生报错

%OSPF-4-NET_TYPE_MISMATCH: Received Hello from 123.5.5.5 on Ethernet0/0 indicating a  potential 
             network type mismatch

和R5的邻居关系报错了，提示ospf网络类型不一致

问题1. R22的e0/0接口配置了网络类型

R5#show run interface e1/0
Building configuration...

Current configuration : 83 bytes
!
interface Ethernet1/0
 ip address 134.56.78.41 255.255.255.252
 duplex auto
end

R22#show run interface e0/0
Building configuration...

Current configuration : 115 bytes
!
interface Ethernet0/0
 ip address 134.56.78.42 255.255.255.252
 ip ospf network point-to-point
 duplex auto
end

修改R22的e0/0口， no掉ptop的网络类型

R5#show ip ospf neighbor
Neighbor ID     Pri   State           Dead Time   Address         Interface
123.1.1.1         1   FULL/BDR        00:00:36    123.45.67.17    Ethernet0/0
134.22.22.22      1   FULL/BDR        00:00:33    134.56.78.42    Ethernet1/0


R22(config-if)#do show ip ospf neighbor
Neighbor ID     Pri   State           Dead Time   Address         Interface
123.5.5.5         1   FULL/DR         00:00:36    134.56.78.41    Ethernet0/0

R22与R21之间没有建立OSPF邻居关系。查看R22和R21的OSPF配置

R21#show run | s router ospf 
router ospf 12345
 router-id 134.21.21.21
 max-metric router-lsa
 passive-interface default
 no passive-interface Ethernet2/0
 network 134.21.21.21 0.0.0.0 area 1
 network 134.56.78.38 0.0.0.0 area 1
 network 134.56.78.48 0.0.0.7 area 1
 neighbor 123.3.3.3
 
 
R22(config-if)#do show run | s router ospf  
router ospf 12345
 router-id 134.22.22.22
 passive-interface default
 no passive-interface Ethernet0/0
 no passive-interface Ethernet2/0
 network 134.22.22.22 0.0.0.0 area 1
 network 134.56.78.42 0.0.0.0 area 1
 network 134.56.78.48 0.0.0.7 area 1

邻居配置并无异常。 R22和R21之间并没有配置成被动接口，理论上是可以建立邻居的。查看两台路由器对应的接口配置

R21#show run interface e2/0
Building configuration...

Current configuration : 83 bytes
!
interface Ethernet2/0
 ip address 134.56.78.50 255.255.255.248
 duplex auto
end

R22#show run interface e2/0
Building configuration...

Current configuration : 83 bytes
!
interface Ethernet2/0
 ip address 134.56.78.49 255.255.255.252
 duplex auto
end

问题2. R22和R21之间的IP地址子网掩码长度不一致

根据OSPF的配置文件判断，子网掩码应该是29位，也就是255.255.255.248，修改R22的子网掩码

R22#conf t 
Enter configuration commands, one per line.  End with CNTL/Z.
R22(config)#int e2/0
R22(config-if)#ip address 134.56.78.49 255.255.255.248
R22(config-if)#do show ip ospf neighbor

Neighbor ID     Pri   State           Dead Time   Address         Interface
134.21.21.21      1   FULL/DR         00:00:38    134.56.78.50    Ethernet2/0
123.5.5.5         1   FULL/DR         00:00:36    134.56.78.41    Ethernet0/0

R21和R3之间也需要有邻居关系、但是从上面的配置来看。R21的e0/0配置成了被动接口，

问题3. R21的e0/0口配置了被动接口

修改

R21#conf t 
Enter configuration commands, one per line.  End with CNTL/Z.
R21(config)#int e0/0
R21(config-if)#exit
R21(config)#router ospf 12345
R21(config-router)#no passive-interface e0/0
R21(config-router)#do show run | s router ospf
router ospf 12345
 router-id 134.21.21.21
 max-metric router-lsa
 passive-interface default
 no passive-interface Ethernet0/0
 no passive-interface Ethernet2/0
 network 134.21.21.21 0.0.0.0 area 1
 network 134.56.78.38 0.0.0.0 area 1
 network 134.56.78.48 0.0.0.7 area 1
 neighbor 123.3.3.3
R21(config-router)#do show run interface e0/0
Building configuration...

Current configuration : 83 bytes
!
interface Ethernet0/0
 ip address 134.56.7