22、OSPF配置实验之特殊区域NSSA

1、特殊区域NSSA解析

2、实验拓扑

NSSA过滤的是远端R1的LSA4、LSA5，本端R4的LSA4、LSA5会被转为LSA7，由于LSA7只能存在于NSSA中，其在区域边界路由器R3上将LSA7重新转为LSA5，此时由于NSSA过滤了远端R1的LSA4、LSA5导致R4无法访问R1的lo10:10.10.10.10.故需要在R3上下放默认路由，下放的默认路由为7类路由。

3、实验配置

R1配置

interface Loopback0

 ip address 1.1.1.1 255.255.255.0

interface Loopback10

 ip address 10.10.10.10 255.255.255.0      

interface Serial0/0

 ip address 12.1.1.1 255.255.255.0

 serial restart-delay 0

router eigrp 90

 network 10.10.10.0 0.0.0.255

 no auto-summary

router ospf 110

 router-id 1.1.1.1

 redistribute eigrp 90 subnets

 network 12.1.1.0 0.0.0.255 area 2

R2配置

interface Loopback0

 ip address 2.2.2.2 255.255.255.0

interface Serial0/0

 ip address 12.1.1.2 255.255.255.0

interface Serial0/1

 ip address 23.1.1.2 255.255.255.0

router ospf 110

 router-id 2.2.2.2

 log-adjacency-changes

 network 12.1.1.0 0.0.0.255 area 2

 network 23.1.1.0 0.0.0.255 area 0

R3配置

interface Loopback0

 ip address 3.3.3.3 255.255.255.0

interface Serial0/0

 ip address 34.1.1.3 255.255.255.0

interface Serial0/1

 ip address 23.1.1.3 255.255.255.0

router ospf 110

 router-id 3.3.3.3

 network 23.1.1.0 0.0.0.255 area 0

 network 34.1.1.0 0.0.0.255 area 1

R4配置

interface Loopback0

 ip address 4.4.4.4 255.255.255.0

interface Serial0/0

 ip address 34.1.1.4 255.255.255.0

interface Serial0/1

 ip address 45.1.1.4 255.255.255.0

router ospf 110

 router-id 4.4.4.4

 redistribute rip subnets

 network 34.1.1.0 0.0.0.255 area 1

router rip

 version 2

 network 45.0.0.0

 no auto-summary

R5配置

interface Loopback0

 ip address 5.5.5.5 255.255.255.0

interface Serial0/1

 ip address 45.1.1.5 255.255.255.0

router rip

 version 2

 network 5.0.0.0

 network 45.0.0.0

 no auto-summary

4、实验验证

过滤远端LSA4、LSA5，本端LSA4、LSA5转为LSA7

配置NSSA前

配置NSSA后

LSA7重新转为LSA5

手动下放默认路由