今天来完成一个实验，拓扑图如下
这个实验是为了说明当某个区域配置为NSSA区域时，正如这个图所示的情况，当EIGRP被重分布到OSPF网络时，NSSA区域内的路由器（除了ABR路由器外）是无法学习到此外部路由信息的。必须手动配置一条默认路由，引导路由器访问外部网络
具体配置如下：
R1:<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

interface Loopback0
 ip address 172.16.0.1 255.255.255.0
!
interface Loopback1
 ip address 172.16.1.1 255.255.255.0
!
interface Loopback2
 ip address 172.16.2.1 255.255.255.0
!
interface Loopback3
 ip address 172.16.3.1 255.255.255.0
!
interface Serial0/0
 ip address 192.168.1.1 255.255.255.0
 ip ospf 1 area 1
 serial restart-delay 0
 clock rate 64000
!
router ospf 1
 log-adjacency-changes
 area 1 nssa
 redistribute rip metric 50 subnets
!
router rip
 version 2
 network 172.16.0.0
 no auto-summary

 

 

R2:

interface Serial0/0
 ip address 192.168.2.2 255.255.255.0
 ip ospf 1 area 0
 serial restart-delay 0
 clock rate 64000
!
interface Serial0/1
 ip address 192.168.1.2 255.255.255.0
 ip ospf 1 area 1
 serial restart-delay 0
!
router ospf 1
 log-adjacency-changes
area 1 nssa
!

 

 

R3:

 

interface Serial0/0

 ip address 192.168.3.3 255.255.255.0

 ip ospf 1 area 2

 serial restart-delay 0

 clock rate 64000

!

interface Serial0/1

 ip address 192.168.2.3 255.255.255.0

 ip ospf 1 area 0

 serial restart-delay 0

!!

router ospf 1

 log-adjacency-changes

 

 

R4:

interface Loopback0

 ip address <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" />10.1.0.1 255.255.255.0

!

interface Loopback1

 ip address 10.1.1.1 255.255.255.0

!

interface Loopback2

 ip address 10.1.2.1 255.255.255.0

!

interface Loopback3

 ip address 10.1.3.1 255.255.255.0

!

interface Serial0/0

 no ip address

 shutdown

 serial restart-delay 0

!

interface Serial0/1

 ip address 192.168.3.4 255.255.255.0

 ip ospf 1 area 2

 serial restart-delay 0

!

router eigrp 1

 network 10.0.0.0

 auto-summary

!

router ospf 1

 log-adjacency-changes

 redistribute eigrp 1 metric 50 subnets

 

按上面配置完成后，我们来看看R1上的路由表

r1(config-if)#do sh ip rou

 

     172.16.0.0/24 is subnetted, 4 subnets

C       172.16.0.0 is directly connected, Loopback0

C       172.16.1.0 is directly connected, Loopback1

C       172.16.2.0 is directly connected, Loopback2

C       172.16.3.0 is directly connected, Loopback3

C    192.168.1.0/24 is directly connected, Serial0/0

O IA 192.168.2.0/24 [110/128] via 192.168.1.2, 00:01:07, Serial0/0

O IA 192.168.3.0/24 [110/192] via 192.168.1.2, 00:00:47, Serial0/0

 

果然没有重分发EIGRP后的路由信息。

再来看看R2上的路由条目

r2(config-if)#do sh ip rou

 

     172.16.0.0/24 is subnetted, 4 subnets

O N2    172.16.0.0 [110/50] via 192.168.1.1, 00:00:41, Serial0/1

O N2    172.16.1.0 [110/50] via 192.168.1.1, 00:00:41, Serial0/1

O N2    172.16.2.0 [110/50] via 192.168.1.1, 00:00:41, Serial0/1

O N2    172.16.3.0 [110/50] via 192.168.1.1, 00:00:41, Serial0/1

     10.0.0.0/24 is subnetted, 4 subnets

O E2    10.1.3.0 [110/50] via 192.168.2.3, 00:00:41, Serial0/0

O E2    10.1.2.0 [110/50] via 192.168.2.3, 00:00:41, Serial0/0

O E2    10.1.1.0 [110/50] via 192.168.2.3, 00:00:41, Serial0/0

O E2    10.1.0.0 [110/50] via 192.168.2.3, 00:00:41, Serial0/0

C    192.168.1.0/24 is directly connected, Serial0/1

C    192.168.2.0/24 is directly connected, Serial0/0

O IA 192.168.3.0/24 [110/128] via 192.168.2.3, 00:00:51, Serial0/0

 

R2上是有到达EIGRP网路的路由的。由此我们刚才的结论是正确的。
我们来测试一下

r1(config)#do ping 10.1.0.1

 

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 10.1.0.1, timeout is 2 seconds:

.....

Success rate is 0 percent (0/5)

r1(config)#

 

当我们增加了默认路由后

r1(config)#ip route 0.0.0.0 0.0.0.0 192.168.1.2

r1(config)#do sh ip rou

 

     172.16.0.0/24 is subnetted, 4 subnets

C       172.16.0.0 is directly connected, Loopback0

C       172.16.1.0 is directly connected, Loopback1

C       172.16.2.0 is directly connected, Loopback2

C       172.16.3.0 is directly connected, Loopback3

C    192.168.1.0/24 is directly connected, Serial0/0

O IA 192.168.2.0/24 [110/128] via 192.168.1.2, 00:03:11, Serial0/0

O IA 192.168.3.0/24 [110/192] via 192.168.1.2, 00:02:21, Serial0/0

S*   0.0.0.0/0 [1/0] via 192.168.1.2

再来测试下

r1(config)#do ping 10.1.0.1                   

 

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 10.1.0.1, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 116/150/228 ms

 

OK，实验完成