CCNP-13 OSPF试验9（BSCI）

CCNP-13 OSPF试验9

试验拓扑：

试验要求： R1 R2 R3 全部起 OSPF ，并且按照拓扑划分区域，把 AREA 1 设置成为 NSSA 区域。

试验目的：掌握 OSPF NSSA 的配置方法，并且知道和理解 NSSA 的作用以及 NSSA 区域中路由器的 LSA 的类型。

实验配置：

R1 ：

interface Loopback0

 ip address 1.1.1 .1 255.255.255.0

 ip ospf network point-to-point

!

interface Loopback1

 ip address 172.17.1.1 255.255.255.0

 ip ospf network point-to-point

!

interface Loopback2

 ip address 172.17.2.1 255.255.255.0

 ip ospf network point-to-point

!

interface Loopback3

 ip address 100.100.100.100 255.255.255.0

!

interface Serial1/0

 ip address 199.99.1.1 255.255.255.0

 serial restart-delay 0

!

router ospf 100

 router-id 1.1.1 .1

 log-adjacency-changes

 redistribute rip subnets

 network 172.17.1.0 0.0.0 .255 area 0

 network 172.17.2.0 0.0.0 .255 area 0

 network 199.99.1.0 0.0.0 .255 area 0

!

router rip

 version 2

 network 100.0.0.0

 

R2 ：

interface Loopback0

 ip address 2.2.2 .2 255.255.255.0

 ip ospf network point-to-point

!

interface Serial1/0

 ip address 199.99.1.2 255.255.255.0

 serial restart-delay 0

 clock rate 64000

!

interface Serial1/1

 ip address 199.99.2.1 255.255.255.0

 serial restart-delay 0

 clock rate 64000

!

router ospf 100

 router-id 2.2.2 .2

 log-adjacency-changes

 area 1 nssa

 network 199.99.1.0 0.0.0 .255 area 0

 network 199.99.2.0 0.0.0 .255 area 1

 

R3 ：

interface Loopback0

 ip address 3.3.3 .3 255.255.255.0

 ip ospf network point-to-point

!

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 Serial1/0

 ip address 199.99.2.2 255.255.255.0

 serial restart-delay 0

!

router ospf 100

 router-id 3.3.3 .3

 log-adjacency-changes

 area 1 nssa

 redistribute rip subnets

 network 199.99.2.0 0.0.0 .255 area 1

!

router rip

 version 2

 network 172.16.0.0

以上为基本配置，注意用红颜色标记的部分。这样配置完成后就把 AREA 1 配置成为了 NSSA 区域， NSSA 区域具有 STUB 区域的特性，并且 STUB 区域内部可以有 ASBR ，但是 NSSA 区域内可以有 ASBR 。下面在 R2 上查看一下路由表：

R2#show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

       D - EIGRP, EX - EIGRP external, O - OSPF , IA - OSPF inter area

       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

       E1 - OSPF external type 1, E2 - OSPF external type 2

       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

       ia - IS-IS inter area, * - candidate default, U - per-user static route

       o - ODR, P - periodic downloaded static route

 

Gateway of last resort is not set

 

     2.0.0 .0/24 is subnetted, 1 subnets

C       2.2.2 .0 is directly connected, Loopback0

     100.0.0.0/24 is subnetted, 1 subnets

O E2    100.100.100.0 [110/20] via 199.99.1.1, 00:00:08, Serial1/0

     172.17.0.0/24 is subnetted, 2 subnets

O       172.17.1.0 [110/65] via 199.99.1.1, 00:00:08, Serial1/0

O       172.17.2.0 [110/65] via 199.99.1.1, 00:00:08, Serial1/0

     172.16.0.0/24 is subnetted, 3 subnets

O N2    172.16.1.0 [110/20] via 199.99.2.2, 00:00:08, Serial1/1

O N2    172.16.2.0 [110/20] via 199.99.2.2, 00:00:08, Serial1/1

O N2    172.16.3.0 [110/20] via 199.99.2.2, 00:00:08, Serial1/1

C    199.99.2.0/24 is directly connected, Serial1/1

C    199.99.1.0/24 is directly connected, Serial1/0

发现有三条 O N2 路由，这是 NSSA 独有的特性，他把 5 类 LSA 通过 NSSA 区域的 ASBR 转变为 7 类 LSA 后向区域内洪泛，查看一下 LSDB ：

R2#show ip ospf database

 

            OSPF Router with ID ( 2.2.2 .2) (Process ID 100)

 

                Router Link States (Area 0)

 

Link ID         ADV Router      Age         Seq#       Checksum Link count

1.1.1 .1         1.1.1 .1         19          0x80000005 0x00494B 4

2.2.2 .2         2.2.2 .2         67          0x80000003 0x00E848 2

 

                Summary Net Link States (Area 0)

 

Link ID         ADV Router      Age         Seq#       Checksum

199.99.2.0      2.2.2 .2         186         0x80000001 0x00EBDB

 

                Router Link States (Area 1)

 

Link ID         ADV Router      Age         Seq#       Checksum Link count

2.2.2 .2         2.2.2 .2         62          0x80000004 0x00E 43C 2

3.3.3 .3         3.3.3 .3         60          0x80000004 0x00819B 2

 

                Summary Net Link States (Area 1)

 

Link ID         ADV Router      Age         Seq#       Checksum

172.17.1.0      2.2.2 .2         68          0x80000002 0x00E04D

172.17.2.0      2.2.2 .2         68          0x80000002 0x00D557

199.99.1.0      2.2.2 .2         68          0x80000002 0x 009A 27

 

                Type-7 AS External Link States (Area 1)

 

Link ID         ADV Router      Age         Seq#       Checksum Tag

172.16.1.0      3.3.3 .3         65          0x80000001 0x00DCC0 0

172.16.2.0      3.3.3 .3         65          0x80000001 0x00D1CA 0

172.16.3.0      3.3.3 .3         65          0x80000001 0x 00C 6D4 0

 

                Type-5 AS External Link States

 

Link ID         ADV Router      Age         Seq#       Checksum Tag

100.100.100.0   1.1.1 .1         18          0x80000001 0x00ABC3 0

172.16.1.0      2.2.2 .2         47          0x80000001 0x 008F 1C 0

172.16.2.0      2.2.2 .2         47          0x80000001 0x008426 0

172.16.3.0      2.2.2 .2         47          0x80000001 0x007930 0

看到 LSDB 中有 7 类的 LSA 出现。

再看一下 R1 的路由表：

R1#show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

       D - EIGRP, EX - EIGRP external, O - OSPF , IA - OSPF inter area

       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

       E1 - OSPF external type 1, E2 - OSPF external type 2

       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

       ia - IS-IS inter area, * - candidate default, U - per-user static route

       o - ODR, P - periodic downloaded static route

 

Gateway of last resort is not set

 

     1.0.0 .0/24 is subnetted, 1 subnets

C       1.1.1 .0 is directly connected, Loopback0

     100.0.0.0/24 is subnetted, 1 subnets

C       100.100.100.0 is directly connected, Loopback3

     172.17.0.0/24 is subnetted, 2 subnets

C       172.17.1.0 is directly connected, Loopback1

C       172.17.2.0 is directly connected, Loopback2

     172.16.0.0/24 is subnetted, 3 subnets

O E2    172.16.1.0 [110/20] via 199.99.1.2, 00:00:33, Serial1/0

O E2    172.16.2.0 [110/20] via 199.99.1.2, 00:00:33, Serial1/0

O E2    172.16.3.0 [110/20] via 199.99.1.2, 00:00:33, Serial1/0

O IA 199.99.2.0/24 [110/128] via 199.99.1.2, 00:00:49, Serial1/0

C    199.99.1.0/24 is directly connected, Serial1/0

同样是这三条路由，但是在 AREA 0 区域内看到的是 O E2 路由，也就是说 NSSA 区域的 ABR 把 7 类 LSA 又转变为 5 类 LSA 后，再向其他区域洪泛。

下面在 R3 上 show ip route 看看路由表：

R3#show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

       D - EIGRP, EX - EIGRP external, O - OSPF , IA - OSPF inter area

       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

       E1 - OSPF external type 1, E2 - OSPF external type 2

       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

       ia - IS-IS inter area, * - candidate default, U - per-user static route

       o - ODR, P - periodic downloaded static route

 

Gateway of last resort is not set

 

     3.0.0 .0/24 is subnetted, 1 subnets

C       3.3.3 .0 is directly connected, Loopback0

     172.17.0.0/24 is subnetted, 2 subnets

O IA    172.17.1.0 [110/129] via 199.99.2.1, 00:00:36, Serial1/0

O IA    172.17.2.0 [110/129] via 199.99.2.1, 00:00:36, Serial1/0

     172.16.0.0/24 is subnetted, 3 subnets

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    199.99.2.0/24 is directly connected, Serial1/0

O IA 199.99.1.0/24 [110/128] via 199.99.2.1, 00:00:36, Serial1/0

我们发现了 3 条区域间路由，但是并没有到 100.100.100.0/24 的路由，这与 STUB 区域的 ABR 把 5 类 LSA 转变为 3 类 LSA 后洪泛不太一样，在这里， NSSA 区域的 ABR 默认是不会注入默认路由的，但是可以通过在 NSSA 区域的 ABR 的 OSPF NSSA 配置中添加 default-information-originate no-summary 选项来解决这个问题，下面为添加了 default-information-originate no-summary 后路由表的变化：

R2(config-router)#area 1 nssa default-information-originate

R3#show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

       D - EIGRP, EX - EIGRP external, O - OSPF , IA - OSPF inter area

       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

       E1 - OSPF external type 1, E2 - OSPF external type 2

       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

       ia - IS-IS inter area, * - candidate default, U - per-user static route

       o - ODR, P - periodic downloaded static route

 

Gateway of last resort is 199.99.2.1 to network 0.0.0 .0

 

     3.0.0 .0/24 is subnetted, 1 subnets

C       3.3.3 .0 is directly connected, Loopback0

     172.17.0.0/24 is subnetted, 2 subnets

O IA    172.17.1.0 [110/129] via 199.99.2.1, 00:00:49, Serial1/0

O IA    172.17.2.0 [110/129] via 199.99.2.1, 00:00:49, Serial1/0

     172.16.0.0/24 is subnetted, 3 subnets

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    199.99.2.0/24 is directly connected, Serial1/0

O IA 199.99.1.0/24 [110/128] via 199.99.2.1, 00:00:49, Serial1/0

O*N2 0.0.0 .0/0 [110/1] via 199.99.2.1, 00:00:00, Serial1/0

可以看到最后面有一条 O*N2 的默认路由，下一条地址是 199.99.2.1 ，也就是 ABR 的地址。 OK ，这样的话就可以通过默认路由到达 100.100.100.0/24 了。

下面我们来把 AREA 1 配置成为完全 NSSA 区域。与完全 STUB 配置方法相同，只需在路由配置模式中输入：

area 1 nssa default-information-originate no-summary

这样， AREA 1 区玉酒杯配置成为了一个完全 NSSA 区域。完全 NSSA 区域也具有完全 STUB 区域的特性，查看一下 R3 的路由表就可以知道了：

R3#show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

       D - EIGRP, EX - EIGRP external, O - OSPF , IA - OSPF inter area

       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

       E1 - OSPF external type 1, E2 - OSPF external type 2

       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

       ia - IS-IS inter area, * - candidate default, U - per-user static route

       o - ODR, P - periodic downloaded static route

 

Gateway of last resort is 199.99.2.1 to network 0.0.0 .0

 

     3.0.0 .0/24 is subnetted, 1 subnets

C       3.3.3 .0 is directly connected, Loopback0

     172.16.0.0/24 is subnetted, 3 subnets

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    199.99.2.0/24 is directly connected, Serial1/0

O*I A 0.0.0 .0/0 [110/65] via 199.99.2.1, 00:00:36, Serial1/0

可以发现就剩下一条默认路由了，查看一下 LSDB ：

R3#show ip ospf database

 

            OSPF Router with ID ( 3.3.3 .3) (Process ID 100)

 

                Router Link States (Area 1)

 

Link ID         ADV Router      Age         Seq#       Checksum Link count

2.2.2 .2         2.2.2 .2         36          0x80000003 0x00E63B 2

3.3.3 .3         3.3.3 .3         38          0x80000002 0x008599 2

 

                Summary Net Link States (Area 1)

 

Link ID         ADV Router      Age         Seq#       Checksum

0.0.0 .0         2.2.2 .2         49          0x80000001 0x00FC31

 

                Type-7 AS External Link States (Area 1)

 

Link ID         ADV Router      Age         Seq#       Checksum Tag

0.0.0 .0         2.2.2 .2         49          0x80000001 0x003744 0

172.16.1.0      3.3.3 .3         45          0x80000001 0x00DCC0 0

172.16.2.0      3.3.3 .3         45          0x80000001 0x00D1CA 0

172.16.3.0      3.3.3 .3         45          0x80000001 0x 00C 6D4 0

可以看到 R3 的 LSDB 里面就剩下一条 0.0.0 .0 的 3 类 LSA 了。

实验总结：掌握 OSPF NSSA 和完全 NSSA 的配置方法，并且知道和理解 NSSA 的主要特性：不会自动注入默认路由， NSSA 区域中的 ASBR 将 5 类 LSA 转变为 7 类 LSA 向区域内洪泛，然后 NSSA 区域的 ABR 又将 7 类 LSA 转变为 5 类 LSA 向其他区域洪泛。