OSPF特殊区域总结
一、拓扑图
二、实验目的
观察stub区域以及NSSA区域的路由以及默认路由是如何产生的
说明：不启动R1和R2，启动其他路由器
三、实验步骤
STUB：
1.将AREA1 配置成STUB区域，看STUB区域的配置以及LSA和默认路由的生成
在R7上配置将RIP重分发到OSPF110，
router ospf 110
redistribute rip subnets
在R5上看路由表，结果显示有区域间的路由以及外部路由。区域间由用O IA标识，外部路由用O E2标识
R5#show ip route ospf
34.0.0.0/24 is subnetted, 1 subnets
O IA 34.1.1.0 [110/74] via 35.1.1.3, 00:05:32, Serial0/1
3.0.0.0/32 is subnetted, 1 subnets
O IA 3.3.3.3 [110/65] via 35.1.1.3, 00:05:32, Serial0/1
36.0.0.0/24 is subnetted, 1 subnets
O IA 36.1.1.0 [110/128] via 35.1.1.3, 00:05:32, Serial0/1
6.0.0.0/32 is subnetted, 4 subnets
O IA 6.6.2.6 [110/129] via 35.1.1.3, 00:04:52, Serial0/1
O IA 6.6.3.6 [110/129] via 35.1.1.3, 00:04:42, Serial0/1
O IA 6.6.0.6 [110/129] via 35.1.1.3, 00:04:52, Serial0/1
O IA 6.6.1.6 [110/129] via 35.1.1.3, 00:04:52, Serial0/1
7.0.0.0/32 is subnetted, 1 subnets
O IA 7.7.7.7 [110/139] via 35.1.1.3, 00:04:19, Serial0/1
8.0.0.0/24 is subnetted, 4 subnets
O E2 8.8.0.0 [110/20] via 35.1.1.3, 00:00:39, Serial0/1
O E2 8.8.1.0 [110/20] via 35.1.1.3, 00:00:39, Serial0/1
O E2 8.8.2.0 [110/20] via 35.1.1.3, 00:00:39, Serial0/1
O E2 8.8.3.0 [110/20] via 35.1.1.3, 00:00:39, Serial0/1
78.0.0.0/24 is subnetted, 1 subnets
O E2 78.1.1.0 [110/20] via 35.1.1.3, 00:00:39, Serial0/1
47.0.0.0/24 is subnetted, 1 subnets
O IA 47.1.1.0 [110/138] via 35.1.1.3, 00:05:32, Serial0/1
2.将区域1配置成Stub，在区域1的所有路由器上面都配置上 area 1 stub
R5#show ip route ospf
34.0.0.0/24 is subnetted, 1 subnets
O IA 34.1.1.0 [110/74] via 35.1.1.3, 00:00:08, Serial0/1
3.0.0.0/32 is subnetted, 1 subnets
O IA 3.3.3.3 [110/65] via 35.1.1.3, 00:00:08, Serial0/1
36.0.0.0/24 is subnetted, 1 subnets
O IA 36.1.1.0 [110/128] via 35.1.1.3, 00:00:08, Serial0/1
6.0.0.0/32 is subnetted, 4 subnets
O IA 6.6.2.6 [110/129] via 35.1.1.3, 00:00:08, Serial0/1
O IA 6.6.3.6 [110/129] via 35.1.1.3, 00:00:08, Serial0/1
O IA 6.6.0.6 [110/129] via 35.1.1.3, 00:00:08, Serial0/1
O IA 6.6.1.6 [110/129] via 35.1.1.3, 00:00:08, Serial0/1
7.0.0.0/32 is subnetted, 1 subnets
O IA 7.7.7.7 [110/139] via 35.1.1.3, 00:00:08, Serial0/1
47.0.0.0/24 is subnetted, 1 subnets
O IA 47.1.1.0 [110/138] via 35.1.1.3, 00:00:08, Serial0/1
O*IA 0.0.0.0/0 [110/65] via 35.1.1.3, 00:00:08, Serial0/1
结果：Stub区域里没有外部路由，去往外部的路由由ABR自动向该区域的路由器下放一条3类默认路由，Metric值为1
Stub区域里没有LSA4/5，该区域不能存在ASBR
该区域有区域间的路由
Totally Stubby区域
1.配置，在Stub区域的ABR上配置一条命令 no－summary，过滤掉LSA3
Totally Stubby区域的路由器只有区域内部的路由以及一条指向ABR的默认路由去往区域间以及外部
在R5上查看路由表，对比Stub区域
R5#show ip route ospf
O*IA 0.0.0.0/0 [110/65] via 35.1.1.3, 00:00:13, Serial0/1
R5#show ip ospf database
OSPF Router with ID (5.5.5.5) (Process ID 110)
Router Link States (Area 1)
Link ID ADV Router Age Seq# Checksum Link count
3.3.3.3 3.3.3.3 423 0x80000004 0x00B177 2
5.5.5.5 5.5.5.5 423 0x80000004 0x007486 3
Summary Net Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
0.0.0.0 3.3.3.3 43 0x80000002 0x0055DB
NSSA区域：
将上图的区域3 配置成NSSA区域，将R6的四个环回口配置成RIP路由，并重分发到OSPF中，查看NSSA区域的路由表
在R4和R7上配置：area 3 nssa这条命令，以把这两台路由的区域3配置成为NSSA区域。
看R7的路由表，可以看到有8.8.0.0/22的路由，但是没有去往6.6.0.0/22的路由。
同时在R4上看路由表，发现在去往6.6.0.0/22的路由，但没有将默认路由发送到NSSA区域的内部路由器
R7#show ip route
34.0.0.0/24 is subnetted, 1 subnets
O IA 34.1.1.0 [110/74] via 47.1.1.4, 00:01:18, Serial0/2
35.0.0.0/24 is subnetted, 1 subnets
O IA 35.1.1.0 [110/138] via 47.1.1.4, 00:01:18, Serial0/2
3.0.0.0/32 is subnetted, 1 subnets
O IA 3.3.3.3 [110/75] via 47.1.1.4, 00:01:18, Serial0/2
5.0.0.0/32 is subnetted, 1 subnets
O IA 5.5.5.5 [110/139] via 47.1.1.4, 00:01:18, Serial0/2
36.0.0.0/24 is subnetted, 1 subnets
O IA 36.1.1.0 [110/138] via 47.1.1.4, 00:01:18, Serial0/2
7.0.0.0/24 is subnetted, 1 subnets
C 7.7.7.0 is directly connected, Loopback0
8.0.0.0/24 is subnetted, 4 subnets
R 8.8.0.0 [120/1] via 78.1.1.8, 00:00:22, Serial0/3
R 8.8.1.0 [120/1] via 78.1.1.8, 00:00:22, Serial0/3
R 8.8.2.0 [120/1] via 78.1.1.8, 00:00:22, Serial0/3
R 8.8.3.0 [120/1] via 78.1.1.8, 00:00:22, Serial0/3
78.0.0.0/24 is subnetted, 1 subnets
C 78.1.1.0 is directly connected, Serial0/3
47.0.0.0/24 is subnetted, 1 subnets
C 47.1.1.0 is directly connected, Serial0/2
总结：
1.NSSA区域允许接入ASBR，以引入外部路由
2.不允许非本区域的外部路由进入本区域，也就是说过滤掉了LSA4/5.
3.NSSA区域的ABR不会自动生成一条默认路由去往区域内部的路由器，需手工输入：area 3 nssa default-information-originate
注意，不能在路由进程中输入:default-information originate，这条命令不起效，不能向R7注入默认路由
此时再看R7的路由表
34.0.0.0/24 is subnetted, 1 subnets
O IA 34.1.1.0 [110/74] via 47.1.1.4, 00:02:54, Serial0/2
35.0.0.0/24 is subnetted, 1 subnets
O IA 35.1.1.0 [110/138] via 47.1.1.4, 00:02:54, Serial0/2
3.0.0.0/32 is subnetted, 1 subnets
O IA 3.3.3.3 [110/75] via 47.1.1.4, 00:02:54, Serial0/2
5.0.0.0/32 is subnetted, 1 subnets
O IA 5.5.5.5 [110/139] via 47.1.1.4, 00:02:54, Serial0/2
36.0.0.0/24 is subnetted, 1 subnets
O IA 36.1.1.0 [110/138] via 47.1.1.4, 00:02:54, Serial0/2
7.0.0.0/24 is subnetted, 1 subnets
C 7.7.7.0 is directly connected, Loopback0
8.0.0.0/24 is subnetted, 4 subnets
R 8.8.0.0 [120/1] via 78.1.1.8, 00:00:05, Serial0/3
R 8.8.1.0 [120/1] via 78.1.1.8, 00:00:05, Serial0/3
R 8.8.2.0 [120/1] via 78.1.1.8, 00:00:05, Serial0/3
R 8.8.3.0 [120/1] via 78.1.1.8, 00:00:05, Serial0/3
78.0.0.0/24 is subnetted, 1 subnets
C 78.1.1.0 is directly connected, Serial0/3
47.0.0.0/24 is subnetted, 1 subnets
C 47.1.1.0 is directly connected, Serial0/2
O*N2 0.0.0.0/0 [110/1] via 47.1.1.4, 00:01:30, Serial0/2
多了一条7类LSA发布的外部路由
Totally NSSA
在NSSA区域的基础上，减少了3类LSA。
配置在NSSA区域的ABR上，加上一条命令：area 3 nssa no-summary default-information-originate
R7#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 47.1.1.4 to network 0.0.0.0
7.0.0.0/24 is subnetted, 1 subnets
C 7.7.7.0 is directly connected, Loopback0
8.0.0.0/24 is subnetted, 4 subnets
R 8.8.0.0 [120/1] via 78.1.1.8, 00:00:02, Serial0/3
R 8.8.1.0 [120/1] via 78.1.1.8, 00:00:02, Serial0/3
R 8.8.2.0 [120/1] via 78.1.1.8, 00:00:02, Serial0/3
R 8.8.3.0 [120/1] via 78.1.1.8, 00:00:02, Serial0/3
78.0.0.0/24 is subnetted, 1 subnets
C 78.1.1.0 is directly connected, Serial0/3
47.0.0.0/24 is subnetted, 1 subnets
C 47.1.1.0 is directly connected, Serial0/2
O*IA 0.0.0.0/0 [110/65] via 47.1.1.4, 00:00:06, Serial0/2
特殊区域的总结
| 区域名称 |
过滤的LSA |
路由 |
是否自动生成默认路由 |
配置命令 |
| Stub |
LSA4/5 |
区域内及区域间的路由 |
ABR自动生成 |
区域内所有路由器配置Area AID stub |
| Totally Stubby |
LSA4/5 LSA3 |
区域内路由 |
ABR自动生成 |
区域内Area AID stub ABR :Aere AID stub no-summary |
| NSSA |
LSA4/5 允许LSA7 |
区域内及区域间的路由 允许本区域引入的外部路由ON1/2 |
在ABR上配置 Area aid nssa default-information-originate |
区域内所有路由器配置 Area aid nssa |
| Totally NSSA |
LSA4/5 LSA3 允许LSA7 |
区域内路由 允许本区域引入的外部路由ON1/2 |
在ABR上配置 Area aid nssa no-summary default-information-originate |
区域内所有路由器配置area aid nssa ABR:area aid nssa no-summary |