原文链接：https://yq.aliyun.com/articles/480040
环境：三台路由器串口相连，其它接口配置如图
1.在area 1配置ospf虚链路,router-id如图配置
2.将R1的LOOP口配置ospf手工路由汇总
3. 配置ospf接口验证（R1 和R2）
4.使用show命令查看结果
配置三个路由器接口使其连通。
R1(config)# interface Loopback0
R1(config-if)# ip address 30.1.1.1 255.255.255.0
R1(config)# interface Loopback1
R1(config-if)# ip address 30.1.2.1 255.255.255.0
R1(config)# interface Loopback2
R1(config-if)# ip address 30.1.3.1 255.255.255.0
R1(config)# interface s0
R1(config-if)# ip address 10.1.1.1 255.255.255.0
R1(config-if)#no shutdown
R2(config)# interface Loopback0
R2(config-if)# ip address 50.1.1.1 255.255.255.0
R2(config)# interface s0
R2(config-if)# ip address 10.1.1.2 255.255.255.0
R2(config-if)#clockrate 64000
R2(config-if)#no shutdown
R2(config)# interface s1
R2(config-if)# ip address 20.1.1.1 255.255.255.0
R2(config-if)#no shutdown
R3(config)# interface Loopback0
R3(config-if)# ip address 40.1.1.1 255.255.255.0
R3(config)# interface s1
R3(config-if)# ip address 20.1.1.2 255.255.255.0
R3(config-if)#clockrate 64000
R3(config)#no shutdown
配置ospf
R1(config)#router ospf 1 启用ospf协议，进程号为1
R1(config-router)#router-id 1.1.1.1 配置router-id
R1(config-router)#network 10.1.1.0 0.0.0.255 area 1 将接口参与到区域1内
R1(config-router)#network 30.1.1.0 0.0.0.255 area 0 将接口参与到区域0内
R1(config-router)#network 30.1.2.0 0.0.0.255 area 0
R1(config-router)#network 30.1.3.0 0.0.0.255 area 0
R2(config)#router ospf 1
R2(config-router)#router-id 2.2.2.2
R2(config-router)#network 10.1.1.0 0.0.0.255 area 1
R2(config-router)#network 20.1.1.0 0.0.0.255 area 2 à将接口参与到区域2内
R2(config-router)#network 50.1.1.0 0.0.0.255 area 1
R3(config)#router ospf 2
R3(config-router)#router-id 3.3.3.3
R3(config-router)#network 20.1.1.0 0.0.0.255 area 2
R3(config-router)#network 40.1.1.0 0.0.0.255 area 2
步骤三：配置ospf虚链路
R1的配置
R1(config)#router ospf 1
R1(config-router)# area 1 virtual-link 2.2.2.2 à配置虚电路,指对端的router-id
R2的配置
R2(config)#router ospf 1
R2(config-router)# area 1 virtual-link 1.1.1.1
步骤四：配置ospf手工路由汇总
R1的配置
R1(config)#router ospf 1
R1(config-router)# area 0 range 30.1.0.0 255.255.252.0 à手工汇总路由
R2的配置
R2(config)#router ospf 1
R2(config-router)# area 0 range 30.1.0.0 255.255.252.0 à因你的区域0已经延伸到此
步骤五：配置ospf接口验证（R1 和R2）
R1的配置
R1(config)# interface Serial0
R1(config-if)# ip ospf authentication message-digest à启用验证
R1(config-if)# ip ospf message-digest-key 1 md5 cisco à定义密钥
R2的配置
R2(config)# interface Serial0
R2(config-if)# ip ospf authentication message-digest
R2(config-if)# ip ospf message-digest-key 1 md5 cisco à两端必须一致
步骤六：查看路由表
R1#show ip route
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
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
50.0.0.0/32 is subnetted, 1 subnets
O 50.1.1.1 [110/65] via 10.1.1.2, 00:09:41, Serial0 àOSPF域内学来的路由条目
20.0.0.0/24 is subnetted, 1 subnets
O IA 20.1.1.0 [110/128] via 10.1.1.2, 00:09:31, Serial0 àOSPF域间学来的路由条目
40.0.0.0/32 is subnetted, 1 subnets
O IA 40.1.1.1 [110/129] via 10.1.1.2, 00:09:31, Serial0
10.0.0.0/24 is subnetted, 1 subnets
C 10.1.1.0 is directly connected, Serial0
30.0.0.0/8 is variably subnetted, 4 subnets, 2 masks
C 30.1.3.0/24 is directly connected, Loopback2
C 30.1.2.0/24 is directly connected, Loopback1
C 30.1.1.0/24 is directly connected, Loopback0
O 30.1.0.0/22 is a summary, 00:09:32, Null0 à手工汇总的条目
R2#show ip route
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
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
50.0.0.0/24 is subnetted, 1 subnets
C 50.1.1.0 is directly connected, Loopback0
20.0.0.0/24 is subnetted, 1 subnets
C 20.1.1.0 is directly connected, Serial1
40.0.0.0/32 is subnetted, 1 subnets
O 40.1.1.1 [110/65] via 20.1.1.2, 00:04:48, Serial1
10.0.0.0/24 is subnetted, 1 subnets
C 10.1.1.0 is directly connected, Serial0
30.0.0.0/8 is variably subnetted, 4 subnets, 2 masks
O 30.1.2.1/32 [110/65] via 10.1.1.1, 00:04:38, Serial0
O 30.1.3.1/32 [110/65] via 10.1.1.1, 00:04:39, Serial0
O 30.1.0.0/22 is a summary, 00:04:39, Null0
O 30.1.1.1/32 [110/65] via 10.1.1.1, 00:04:39, Serial0
R3#show ip route
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
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
50.0.0.0/32 is subnetted, 1 subnets
O IA 50.1.1.1 [110/65] via 20.1.1.1, 00:02:02, Serial1
20.0.0.0/24 is subnetted, 1 subnets
C 20.1.1.0 is directly connected, Serial1
40.0.0.0/24 is subnetted, 1 subnets
C 40.1.1.0 is directly connected, Loopback0
10.0.0.0/24 is subnetted, 1 subnets
O IA 10.1.1.0 [110/128] via 20.1.1.1, 00:02:02, Serial1
30.0.0.0/22 is subnetted, 1 subnets
O IA 30.1.0.0 [110/129] via 20.1.1.1, 00:01:47, Serial1
步骤七：查看邻居表
R1#show ip ospf neighbor à邻居已建立，点对点无DR之说
Neighbor ID Pri State Dead Time Address Interface
2.2.2.2 1 FULL/ - 00:00:33 10.1.1.2 Serial0
R2#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
1.1.1.1 1 FULL/ - 00:00:33 10.1.1.1 Serial0
3.3.3.3 1 FULL/ - 00:00:34 20.1.1.2 Serial1
R3#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
2.2.2.2 1 FULL/ - 00:00:37 20.1.1.1 Serial1
步骤八：用ping命令测试
R1#ping 40.1.1.1 à测试连通性
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 56/60/68 ms
R1#ping 50.1.1.1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 32/32/36 ms
R2#ping 30.1.1.1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 32/32/32 ms
步骤九：显示当前配置信息
R1的配置信息
R1#sh run
hostname R1
!
interface Loopback0
ip address 30.1.1.1 255.255.255.0
!
interface Loopback1
ip address 30.1.2.1 255.255.255.0
!
interface Loopback2
ip address 30.1.3.1 255.255.255.0
!
interface Serial0
ip address 10.1.1.1 255.255.255.0
ip ospf authentication message-digest
ip ospf message-digest-key 1 md5 cisco
!
router ospf 1
router-id 1.1.1.1
area 0 range 30.1.0.0 255.255.252.0
area 1 virtual-link 2.2.2.2
network 10.1.1.0 0.0.0.255 area 1
network 30.1.1.0 0.0.0.255 area 0
network 30.1.2.0 0.0.0.255 area 0
network 30.1.3.0 0.0.0.255 area 0
end
R2#sh run
hostname R2
interface Loopback0
ip address 50.1.1.1 255.255.255.0
!
interface Serial0
ip address 10.1.1.2 255.255.255.0
ip ospf authentication message-digest
ip ospf message-digest-key 1 md5 cisco
clockrate 64000
!
interface Serial1
ip address 20.1.1.1 255.255.255.0
!
router ospf 1
router-id 2.2.2.2
area 0 range 30.1.0.0 255.255.252.0
area 1 virtual-link 1.1.1.1
network 10.1.1.0 0.0.0.255 area 1
network 20.1.1.0 0.0.0.255 area 2
network 50.1.1.0 0.0.0.255 area 1
end
R3#sh run
Hostname R3
!
interface Loopback0
ip address 40.1.1.1 255.255.255.0
!
interface Serial1
ip address 20.1.1.2 255.255.255.0
clockrate 64000
!
router ospf 2
router-id 3.3.3.3
network 20.1.1.0 0.0.0.255 area 2
network 40.1.1.0 0.0.0.255 area 2
end