OSPF的LSA有11類,常用的也就是1(路由器本身)、3(網絡彙總)、5類(AS外部路由);
7類LSA(是非完全末梢區域下才會産生7類LSA)
NSSA(not-so-stubby area)是由NSSA區域内的 ASBR 路由器始發的 LSA 通告它隻在 NSSA 區域内泛洪;和5類LSA差別就是傳播的範圍(5類是在整個AS區域中泛洪,7類隻能在NSSA區域中泛洪)
如下圖的網絡拓撲:
![](https://img.laitimes.com/img/9ZDMuAjOiMmIsIjOiQnIsIyZuBnL2IDN2AjM0UjNz81ctQzXw12dtMzXtdXLwgHMwUzXodXLn5GcuUjMxUVeqREMFpnUDFUQwglQwE0U2RTUoFDTvl2S39CX5gzLcJEOvwlMw00LcJDMzZWe39CXt92Yu8GdjFTNuMzcvw1LcpDc0RHaiojIsJye.png)
R1/R2在Area 2
R2/R3在Area 0
R3/R4/R5 在Area 1 為NSSA區域
R5/R6模拟的外部網絡。
NSSA區域的配置:
R3的配置資訊:
router ospf 1
log-adjacency-changes
area 1 nssa
redistribute connected subnets
network 192.168.2.0 0.0.0.255 area 0
network 192.168.3.0 0.0.0.255 area 1
!
如果在其他非NSSA區域的邊界路由器上存在外部路由的注入,如RIP的路由注入;
在R1上配置
redistribute rip metric 1 subnets
network 1.1.1.0 0.0.0.255 area 2
network 192.168.1.0 0.0.0.255 area 2
router rip
version 2
redistribute ospf 1 metric 1
network 10.0.0.0
no auto-summary
檢視路由資訊:
R3的路由檢視
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
1.0.0.0/32 is subnetted, 1 subnets
O IA 1.1.1.1 [110/3] via 192.168.2.2, 01:43:05, FastEthernet0/1
2.0.0.0/32 is subnetted, 1 subnets
O 2.2.2.2 [110/2] via 192.168.2.2, 01:43:10, FastEthernet0/1
3.0.0.0/24 is subnetted, 1 subnets
C 3.3.3.0 is directly connected, Loopback3
4.0.0.0/32 is subnetted, 1 subnets
O 4.4.4.4 [110/11] via 192.168.3.4, 01:43:05, Ethernet1/1
5.0.0.0/32 is subnetted, 1 subnets
O 5.5.5.5 [110/21] via 192.168.3.4, 01:43:05, Ethernet1/1
O 192.168.4.0/24 [110/20] via 192.168.3.4, 01:43:05, Ethernet1/1
O N2 192.168.5.0/24 [110/20] via 192.168.3.4, 01:42:58, Ethernet1/1
10.0.0.0/24 is subnetted, 1 subnets
O E2 10.1.1.0 [110/1] via 192.168.2.2, 01:43:06, FastEthernet0/1
O IA 192.168.1.0/24 [110/2] via 192.168.2.2, 01:43:06, FastEthernet0/1
C 192.168.2.0/24 is directly connected, FastEthernet0/1
C 192.168.3.0/24 is directly connected, Ethernet1/1
R4的路由資訊:
R4#show ip route
O IA 1.1.1.1 [110/13] via 192.168.3.3, 01:43:40, Ethernet1/1
O IA 2.2.2.2 [110/12] via 192.168.3.3, 01:43:40, Ethernet1/1
O N2 3.3.3.0 [110/20] via 192.168.3.3, 01:43:40, Ethernet1/1
4.0.0.0/24 is subnetted, 1 subnets
C 4.4.4.0 is directly connected, Loopback4
O 5.5.5.5 [110/11] via 192.168.4.5, 01:43:40, Ethernet1/0
C 192.168.4.0/24 is directly connected, Ethernet1/0
O N2 192.168.5.0/24 [110/20] via 192.168.4.5, 01:43:40, Ethernet1/0
O IA 192.168.1.0/24 [110/12] via 192.168.3.3, 01:43:40, Ethernet1/1
O IA 192.168.2.0/24 [110/11] via 192.168.3.3, 01:43:41, Ethernet1/1
配置完NSSA屬性之後,就會産生相應的域間路由資訊;如果再引入外部路由的情況下,需要在nssa區域的ABR上注入預設的路由保證,NSSA區域的能夠正常通路外部網絡。否則就會出現網絡無法通路的情況;
指令如下:
area 1 nssa default-information-originate
在R4上的路由資訊:
Gateway of last resort is 192.168.3.3 to network 0.0.0.0
O IA 1.1.1.1 [110/13] via 192.168.3.3, 01:55:07, Ethernet1/1
O IA 2.2.2.2 [110/12] via 192.168.3.3, 01:55:07, Ethernet1/1
O N2 3.3.3.0 [110/20] via 192.168.3.3, 01:55:07, Ethernet1/1
O 5.5.5.5 [110/11] via 192.168.4.5, 01:55:07, Ethernet1/0
O N2 192.168.5.0/24 [110/20] via 192.168.4.5, 01:55:07, Ethernet1/0
O IA 192.168.1.0/24 [110/12] via 192.168.3.3, 01:55:07, Ethernet1/1
O IA 192.168.2.0/24 [110/11] via 192.168.3.3, 01:55:07, Ethernet1/1
O*N2 0.0.0.0/0 [110/1] via 192.168.3.3, 00:00:36, Ethernet1/1
NSSA區域的路由起上就會産生一條7類的預設路由,在整個NSSA區域泛洪;同時又有一些域間的路由和預設路由,這樣為了減少路由的條目數就對路由進行簡化,是以産生完全末梢區域對路由進行精簡
指令:area 1 nssa no-summary
完全末梢區域會自動産生一條3類LSA的預設路由并在整個NSSA區域中泛洪:
O N2 3.3.3.0 [110/20] via 192.168.3.3, 00:00:17, Ethernet1/1
O 5.5.5.5 [110/11] via 192.168.4.5, 00:00:17, Ethernet1/0
O N2 192.168.5.0/24 [110/20] via 192.168.4.5, 00:00:17, Ethernet1/0
O*IA 0.0.0.0/0 [110/11] via 192.168.3.3, 00:00:17, Ethernet1/1
檢視資料庫資訊:
Summary Net Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
0.0.0.0 3.3.3.3 137 0x80000001 0x00DE4B
注意:配置完全末梢區域的時候,隻需要在NSSA的ABR上配置就可以,其他的NSSA路由器上正常配置就可以。
如果在NSSA區域和骨幹區域的路由上引入外部路由如在R3上引入外部路由,
在R4上檢視的路由資訊: