OSPF：LSA Type-7 to Type-5 转发地址抑制
1.LSA Type 7 to Type 5
1.1实验拓扑
1.2实验需求（1）按拓扑完成基本配置（2）重分发RIP网络进入OSPF进程，R2连接RIP域的接口网络同时也参与OSPF进程（3）观察R2上产生的LSA Type 7的转发地址（4）观察R3上作为ABR将LSA Type 7转化为LSA Type 5后的转发地址（5）修改R2、R3直连接口网络类型为点到点，观察实验现象
1.3实验步骤（1）LSA Type 7转发地址R2#show ip ospf database nssa-external | include Forward Forward Address: 31.31.12.1此时转发地址继承原路由下一跳
（2）Type 7 to Type 5R3#show ip ospf database external
OSPF Router with ID (3.3.3.3) (Process ID 1)
Type-5 AS External Link States
LS age: 171Options: (No TOS-capability, DC)LS Type: AS External LinkLink State ID: 1.1.1.0 (External Network Number )Advertising Router: 3.3.3.3LS Seq Number: 80000001Checksum: 0xDF66Length: 36Network Mask: /24 Metric Type: 2 (Larger than any link state path) TOS: 0 Metric: 20 Forward Address: 31.31.12.1 External Route Tag: 0可见，当LSA Type 7转化为Type 5以后，通告者将变为NSSA的ABR，同时还会继承LSA Type 7中所携带的Forward Address
（3）修改接口网络类型R2(config-if)#ip ospf network point-to-point
R3(config-if)#ip ospf network point-to-point
R3#show ip ospf database external | include Forward Forward Address: 31.31.12.1对转发地址的继承并没有因为连接ASBR直连接口的网络类型改变而发生变化
1.4实验结论当LSA Type 7转化为LSA Type 5时，LSA Type 5会继承LSA Type 7中的转发地址
2.转发地址抑制
2.1实验拓扑
2.2实验需求（1）按拓扑完成基本配置（2）观察R4上接收到LSA Type 5的相关信息（3）在R4上写一条去往31.31.12.0网段，指向出口null0的静态路由，观察实验现象（4）在NSSA ABR R3上配置转发地址抑制，观察R4上LSA Type 5的转发地址，同时验证去往R1环回口网络的可达性
2.3实验步骤（1）查看LSA Type 5R4#show ip ospf database external | in Forward Forward Address: 31.31.12.1此时继承的下一跳伴随LSA Type 5扩散到OPSF域中
（2）静态路由R4(config)#ip route 31.31.12.0 255.255.255.0 null 0
R4#show ip route ospf 31.0.0.0/24 is subnetted, 3 subnetsO IA 31.31.23.0 via 31.31.34.3, 00:15:25, FastEthernet0/0此时外部网络消失，LSA Type 5被判定失效
（3）转发地址抑制R3(config-router)#area 1 nssa translate type7 suppress-fa //抑制转发地址继承
R4#show ip ospf database external | in Forward Forward Address: 0.0.0.0此时LSA Type 7转化为LSA Type 5时，不再继承转发地址
R4#show ip route ospf 1.0.0.0/24 is subnetted, 1 subnetsO E2 1.1.1.0 via 31.31.34.3, 00:00:52, FastEthernet0/0 31.0.0.0/24 is subnetted, 3 subnetsO IA 31.31.23.0 via 31.31.34.3, 00:17:56, FastEthernet0/0目标网络重新出现在路由表中
2.4实验结论配置转发地址抑制后，新产生的LSA Type 5的转发地址将变为0.0.0.0
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