OSPF特殊區域總結
一、拓撲圖
二、實驗目的
觀察stub區域以及NSSA區域的路由以及預設路由是如何產生的
說明：不啟動R1和R2，啟動其他路由器
三、實驗步驟
STUB：
1.將AREA1 配置成STUB區域，看STUB區域的配置以及LSA和預設路由的生成
在R7上配置將RIP重分發到OSPF110，
router ospf 110
redistribute rip subnets
在R5上看路由表，結果顯示有區域間的路由以及外部路由。區域間由用O IA標識，外部路由用O E2標識
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.將區域1配置成Stub，在區域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
結果：Stub區域裡沒有外部路由，去往外部的路由由ABR自動向該區域的路由器下放一條3類預設路由，Metric值為1
Stub區域裡沒有LSA4/5，該區域不能存在ASBR
該區域有區域間的路由
Totally Stubby區域
1.配置，在Stub區域的ABR上配置一條命令 no－summary，過濾掉LSA3
Totally Stubby區域的路由器只有區域內部的路由以及一條指向ABR的預設路由去往區域間以及外部
在R5上檢視路由表，對比Stub區域
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區域：
將上圖的區域3 配置成NSSA區域，將R6的四個環回口配置成RIP路由，並重分發到OSPF中，檢視NSSA區域的路由表
在R4和R7上配置：area 3 nssa這條命令，以把這兩臺路由的區域3配置成為NSSA區域。
看R7的路由表，可以看到有8.8.0.0/22的路由，但是沒有去往6.6.0.0/22的路由。
同時在R4上看路由表，發現在去往6.6.0.0/22的路由，但沒有將預設路由傳送到NSSA區域的內部路由器
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
總結：
1.NSSA區域允許接入ASBR，以引入外部路由
2.不允許非本區域的外部路由進入本區域，也就是說過濾掉了LSA4/5.
3.NSSA區域的ABR不會自動生成一條預設路由去往區域內部的路由器，需手工輸入：area 3 nssa default-information-originate
注意，不能在路由程序中輸入:default-information originate，這條命令不起效，不能向R7注入預設路由
此時再看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
多了一條7類LSA釋出的外部路由
Totally NSSA
在NSSA區域的基礎上，減少了3類LSA。
配置在NSSA區域的ABR上，加上一條命令：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
特殊區域的總結
|
區域名稱 |
過濾的LSA |
路由 |
是否自動生成預設路由 |
配置命令 |
|
Stub |
LSA4/5 |
區域內及區域間的路由 |
ABR自動生成 |
區域內所有路由器配置Area AID stub |
|
Totally Stubby |
LSA4/5 LSA3 |
區域內路由 |
ABR自動生成 |
區域內Area AID stub ABR :Aere AID stub no-summary |
|
NSSA |
LSA4/5 允許LSA7 |
區域內及區域間的路由 允許本區域引入的外部路由ON1/2 |
在ABR上配置 Area aid nssa default-information-originate |
區域內所有路由器配置 Area aid nssa |
|
Totally NSSA |
LSA4/5 LSA3 允許LSA7 |
區域內路由 允許本區域引入的外部路由ON1/2 |
在ABR上配置 Area aid nssa no-summary default-information-originate |
區域內所有路由器配置area aid nssa ABR:area aid nssa no-summary |
轉載於:https://blog.51cto.com/liu008qing/454213