OSPF中NSSA Suppress FA Feature
【实验拓扑】
【实验基本配置】
1、按照上图配置接口地址及OSPF
2、配置AREA1为NSSA区域
3、R6上配置静态路由160.1.60.0/24 到 Null0，重定向到OSPF中
4、R1上配置更高的路由器ID150.1.100.100，使得LSA7转换LSA5在R1上进行
5、在R1上使用Range过滤area1中150.1.6.0/24 的路由，使用
Range过滤area0中150.1.5.0/24 的路由
【实验要求】
R5能够接收到外部160.1.60.0路由。
【实验分析】
我们按照实验基本配置之后，在R5中接收不到
160.1.60.0/24 外部路由，
上面实验基本配置中没有任何对160.1.60.0/24路由的限制，为什么呢？
原因是：在R6上
外部LSA7转换为LSA5时的转发地址为R6的loopback0地址，OSPF规定
如果指定了外部LSA的转发地址，而这个地址是不可达的，那么这个LSA中包含的地址将不会插入到路由表中，我们知道150.1.6.6 被过滤了，因此R5中也收不到外部路由，此时我们的解决方法是：
在转换期间，可以配置ABR路由器来抑制它的转发地址，这可以使用0.0.0.0代替原有转发地址。当另一台路由器接收到这个抑制了转发地址的类型5外部LSA时，接收路由器将会把要达到外部地址的流量引导到转换类型7到类型5的ABR路由器上，而不是引导到转发地址
【实验配置】
R1：
router ospf 1
area 1 nssa translate type7 suppress-fa
【实验验证】
配置之前----------------------------------------------->>
R5#show ip route ospf
155.1.0.0/24 is subnetted, 2 subnets
O IA 155.1.146.0 [110/74] via 155.1.0.4, 01:17:20, Serial0/0
[110/74] via 155.1.0.1, 01:17:20, Serial0/0
150.1.0.0/16 is variably subnetted, 3 subnets, 2 masks
O IA 150.1.4.4/32 [110/65] via 155.1.0.4, 01:17:20, Serial0/0
O IA 150.1.1.1/32 [110/65] via 155.1.0.1, 01:17:20, Serial0/0
没有160.1.60.0 的外部路由
R5#show ip ospf dat external
OSPF Router with ID (150.1.5.5) (Process ID 1)
Type-5 AS External Link States
LS age: 760
Options: (No TOS-capability, DC)
LS Type: AS External Link
Link State ID: 160.1.60.0 (External Network Number )
Advertising Router: 150.1.100.100
LS Seq Number: 80000008
Checksum: 0xC9ED
Length: 36
Network Mask: /24
Metric Type: 2 (Larger than any link state path)
TOS: 0
Metric: 20
Forward Address:
150.1.6.6
External Route Tag: 0
转发地址为R6的Loopback0地址
配置之后----------------------------------------------->>
R5#show ip route ospf
155.1.0.0/24 is subnetted, 2 subnets
O IA 155.1.146.0 [110/74] via 155.1.0.4, 01:20:23, Serial0/0
[110/74] via 155.1.0.1, 01:20:23, Serial0/0
160.1.0.0/24 is subnetted, 1 subnets
O E2 160.1.60.0 [110/20] via 155.1.0.1, 00:00:03, Serial0/0
150.1.0.0/16 is variably subnetted, 3 subnets, 2 masks
O IA 150.1.4.4/32 [110/65] via 155.1.0.4, 01:20:23, Serial0/0
O IA 150.1.1.1/32 [110/65] via 155.1.0.1, 01:20:23, Serial0/0
“160.1.60.0的外部路由出现了”
R5#show ip ospf database external
OSPF Router with ID (150.1.5.5) (Process ID 1)
Type-5 AS External Link States
Routing Bit Set on this LSA
LS age: 57
Options: (No TOS-capability, DC)
LS Type: AS External Link
Link State ID: 160.1.60.0 (External Network Number )
Advertising Router: 150.1.100.100
LS Seq Number: 80000009
Checksum: 0xA0B9
Length: 36
Network Mask: /24
Metric Type: 2 (Larger than any link state path)
TOS: 0
Metric: 20
Forward Address: 0.0.0.0
External Route Tag: 0
转发地址被配置为了0.0.0.0
【实验基本配置】
R1:
interface Fa 0/0
ip address 155.1.146.1 255.255.255.0
no shut
!
interface Serial 0/0
encapsulation frame-relay
no frame-relay inverse-arp
ip address 155.1.0.1 255.255.255.0
frame-relay map ip 155.1.0.5 105
frame-relay map ip 155.1.0.4 105
ip ospf priority 0
no shutdown
!
interface Loopback0
ip address 150.1.1.1 255.255.255.0
!
router ospf 1
router-id 150.1.100.100
network 155.1.146.1 0.0.0.0 area 1
network 150.1.1.1 0.0.0.0 area 1
network 155.1.0.1 0.0.0.0 area 0
area 1 nssa
area 1 range 150.1.6.0 255.255.255.0 not-adv
area 0 range 150.1.5.0 255.255.255.0 not-adv
R4:
interface Eth 0/1
ip address 155.1.146.4 255.255.255.0
!
interface Serial 0/0
encapsulation frame-relay
no frame-relay inverse-arp
ip address 155.1.0.4 255.255.255.0
frame-relay map ip 155.1.0.5 405
frame-relay map ip 155.1.0.1 405
ip ospf priority 0
!
interface Loopback0
ip address 150.1.4.4 255.255.255.0
!
router ospf 1
router-id 150.1.4.4
network 155.1.146.4 0.0.0.0 area 1
network 150.1.4.4 0.0.0.0 area 1
network 155.1.0.4 0.0.0.0 area 0
area 1 nssa
area 1 range 150.1.6.0 255.255.255.0 not-adv
area 0 range 150.1.5.0 255.255.255.0 not-adv
R5:
interface Serial 0/0
encapsulation frame-relay
no frame-relay inverse-arp
ip address 155.1.0.5 255.255.255.0
frame-relay map ip 155.1.0.4 504
frame-relay map ip 155.1.0.1 501
!
interface Loopback0
ip address 150.1.5.5 255.255.255.0
！
router ospf 1
router-id 150.1.5.5
network 150.1.5.5 0.0.0.0 area 0
network 155.1.0.5 0.0.0.0 area 0
neighbor 155.1.0.4
neighbor 155.1.0.1
area 1 nssa
R6:
interface Gig 0/1
ip address 155.1.146.6 255.255.255.0
!
interface Loopback0
ip address 150.1.6.6 255.255.255.0
!
ip route 160.1.60.0 255.255.255.0 Null0
router ospf 1
redistribute static subnets
router-id 150.1.6.6
network 155.1.146.6 0.0.0.0 area 1
network 150.1.6.6 0.0.0.0 area 1
area 1 nssa