OSPF配置实验之特殊区域NSSA
1、特殊区域NSSA解析区域类型作用默认路由备注命令
stub过滤LSA4、LSA5ABR默认下发3类默认路由，seed cost值为1本区域所有路由器都必须配置成stub，否则邻居起不来，且不能包含ASBR
area 2 stub
area 2 default-cost x
totally stub过滤LSA3、LSA4、LSA5ABR默认下发3类默认路由，seed cost值为1本区域所有路由器都必须配置成stub，否则邻居起不来，且不能包含ASBR，ABR配置成totally stbarea 2 stub no-summary
NSSA过滤远端LSA4、LSA5，本端LSA4、LSA5转为LSA7不下发默认路由，需要在ABR上下放默认路由本区域所有路由器都必须配置成nssa，否则邻居起不来，包含ASBRarea 2 nssa
area 2 nssa default-information orig
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
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