圖同(1)是一樣的
六、show路由信息(在特權模式下show ip route)
RT4:
1.0.0.0/32 is subnetted, 1 subnets
R 1.1.1.1 [120/5] via 172.16.24.1, 00:00:01, Serial0/0
2.0.0.0/32 is subnetted, 1 subnets
R 2.2.2.2 [120/5] via 172.16.24.1, 00:00:01, Serial0/0
3.0.0.0/32 is subnetted, 1 subnets
R 3.3.3.3 [120/5] via 172.16.24.1, 00:00:01, Serial0/0
4.0.0.0/32 is subnetted, 1 subnets
C 4.4.4.4 is directly connected, Loopback0
5.0.0.0/32 is subnetted, 1 subnets
R 5.5.5.5 [120/5] via 172.16.24.1, 00:00:01, Serial0/0
6.0.0.0/32 is subnetted, 1 subnets
R 6.6.6.6 [120/5] via 172.16.24.1, 00:00:01, Serial0/0
172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks
C 172.16.24.0/30 is directly connected, Serial0/0
C 172.16.4.0/24 is directly connected, Ethernet3/0
10.0.0.0/8 is variably subnetted, 10 subnets, 2 masks
R 10.0.15.0/30 [120/5] via 172.16.24.1, 00:00:02, Serial0/0
R 10.1.13.0/30 [120/5] via 172.16.24.1, 00:00:02, Serial0/0
R 10.1.3.0/24 [120/5] via 172.16.24.1, 00:00:02, Serial0/0
R 10.2.2.0/24 [120/5] via 172.16.24.1, 00:00:02, Serial0/0
R 10.1.1.0/24 [120/5] via 172.16.24.1, 00:00:02, Serial0/0
R 10.2.6.0/24 [120/5] via 172.16.24.1, 00:00:02, Serial0/0
R 10.0.5.0/24 [120/5] via 172.16.24.1, 00:00:02, Serial0/0
R 10.2.26.0/30 [120/5] via 172.16.24.1, 00:00:02, Serial0/0
R 10.0.56.0/30 [120/5] via 172.16.24.1, 00:00:02, Serial0/0
R 10.0.50.0/24 [120/5] via 172.16.24.1, 00:00:02, Serial0/0
(注意紅色部分,可以看出來,如果沒有執行重發布的話,單單是RT4上的路由條目是不會有那麼多的,這部分就是通過重發布OSPF區域的路由學習到的,而且,注意,這些路由條目都有一個共同點,那就是開銷都是5,對吧,這樣,在RT2上做的雙向重發布就起到了讓不同的路由協議互聯的效果)
RT3:
1.0.0.0/32 is subnetted, 1 subnets
O IA 1.1.1.1 [110/101] via 10.1.13.1, 00:01:23, Serial0/0
2.0.0.0/32 is subnetted, 1 subnets
O IA 2.2.2.2 [110/401] via 10.1.13.1, 00:01:23, Serial0/0
3.0.0.0/32 is subnetted, 1 subnets
C 3.3.3.3 is directly connected, Loopback0
4.0.0.0/32 is subnetted, 1 subnets
O E1 4.4.4.4 [110/1400] via 10.1.13.1, 00:01:23, Serial0/0
5.0.0.0/32 is subnetted, 1 subnets
O IA 5.5.5.5 [110/201] via 10.1.13.1, 00:01:23, Serial0/0
6.0.0.0/32 is subnetted, 1 subnets
O IA 6.6.6.6 [110/301] via 10.1.13.1, 00:01:23, Serial0/0
172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks
O E1 172.16.24.0/30 [110/1400] via 10.1.13.1, 00:01:23, Serial0/0
O E1 172.16.4.0/24 [110/1400] via 10.1.13.1, 00:01:23, Serial0/0
10.0.0.0/8 is variably subnetted, 10 subnets, 2 masks
O IA 10.0.15.0/30 [110/200] via 10.1.13.1, 00:01:23, Serial0/0
C 10.1.13.0/30 is directly connected, Serial0/0
C 10.1.3.0/24 is directly connected, Ethernet3/0
O IA 10.2.2.0/24 [110/410] via 10.1.13.1, 00:01:23, Serial0/0
O 10.1.1.0/24 [110/110] via 10.1.13.1, 00:01:23, Serial0/0
O IA 10.2.6.0/24 [110/310] via 10.1.13.1, 00:01:23, Serial0/0
O IA 10.0.5.0/24 [110/210] via 10.1.13.1, 00:01:23, Serial0/0
O IA 10.2.26.0/30 [110/400] via 10.1.13.1, 00:01:23, Serial0/0
O IA 10.0.56.0/30 [110/300] via 10.1.13.1, 00:01:23, Serial0/0
O E1 10.0.50.0/24 [110/1200] via 10.1.13.1, 00:01:23, Serial0/0
(前面有OE1的都是通過重發布學習到的路由,此處一分爲二的看。紅色部分:從網段來看不難看出這是RIP區域的路由,這是重發布到OSPF進程1來的;藍色部分:配置RT5的時候,特地留下了一個網段沒有發佈到OSPF區域,然後才執行重發布的,嚴格來說,這個網段不在OSPF協議區域之內,因此也算是“外部路由了”)
RT2:
1.0.0.0/32 is subnetted, 1 subnets
O IA 1.1.1.1 [110/301] via 10.2.26.2, 00:01:28, Serial0/2
2.0.0.0/32 is subnetted, 1 subnets
C 2.2.2.2 is directly connected, Loopback0
3.0.0.0/32 is subnetted, 1 subnets
O IA 3.3.3.3 [110/401] via 10.2.26.2, 00:01:19, Serial0/2
4.0.0.0/32 is subnetted, 1 subnets
R 4.4.4.4 [120/1] via 172.16.24.2, 00:00:23, Serial0/0
5.0.0.0/32 is subnetted, 1 subnets
O IA 5.5.5.5 [110/201] via 10.2.26.2, 00:01:28, Serial0/2
6.0.0.0/32 is subnetted, 1 subnets
O IA 6.6.6.6 [110/101] via 10.2.26.2, 00:01:28, Serial0/2
172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks
C 172.16.24.0/30 is directly connected, Serial0/0
R 172.16.4.0/24 [120/1] via 172.16.24.2, 00:00:23, Serial0/0
10.0.0.0/8 is variably subnetted, 10 subnets, 2 masks
O IA 10.0.15.0/30 [110/300] via 10.2.26.2, 00:01:28, Serial0/2
O IA 10.1.13.0/30 [110/400] via 10.2.26.2, 00:01:28, Serial0/2
O IA 10.1.3.0/24 [110/410] via 10.2.26.2, 00:01:20, Serial0/2
C 10.2.2.0/24 is directly connected, Ethernet3/0
O IA 10.1.1.0/24 [110/310] via 10.2.26.2, 00:01:28, Serial0/2
O 10.2.6.0/24 [110/110] via 10.2.26.2, 00:01:28, Serial0/2
O IA 10.0.5.0/24 [110/210] via 10.2.26.2, 00:01:28, Serial0/2
C 10.2.26.0/30 is directly connected, Serial0/2
O IA 10.0.56.0/30 [110/200] via 10.2.26.2, 00:01:28, Serial0/2
O E1 10.0.50.0/24 [110/1200] via 10.2.26.2, 00:01:18, Serial0/2
(RT2是自制系統邊界路由器,即ASBR,因此既有OSPF的路由條目,也有以R開頭的RIP路由條目)
(其他的設備上的路由就不show了,都跟RT3上是一樣的,只是開銷不一樣)
七、總結
關於重發布
重發布可以將其他的不同的路由協議再一次“發佈”到自己的區域,這樣就能學次到外部的路由了,重發布可以有很多種,當然,上一節單區域配置中的下發缺省也算是一種重發布了。
OSPF防環
可知道OSPF一般是不會出現環路的,不像RIP那樣是一種“偵聽傳言”的路由,它交互的是LSA路由信息,常用的LAS有1、2、3、4、5、7類LSA,各自有不同的作用,而在單區域內,通過LSA計算的路由都是最短路徑優先樹,當然不會有環了,在區域之間,所有的區域都必須跟骨幹區域相連,骨幹區域即區域0,區域0是必須要有的區域,所以,這樣區域間也不會有環路了。
不同區域配置
多區域其實就是將不同的網段發佈到不同的區域,多區域分爲ABR(區域邊界路由器)、ASBR(自制系統邊界路由器),當然還有普通路由器了。ABR上一般都發布了一些網段到不同的區域,所以處在不同區域之間,即ABR。爲什麼要配置多區域呢,這個問題貌似有點糾結,因爲從此實驗看來,OSPF自制系統內的路由條目都是一樣的,除了開銷不同之外,基本沒有什麼可取之處了,但是,OSPF得到廣泛的應用,當然有原因了,特殊區域的配置可以減少路由條目,所以也適用於中、大型的網絡中。