Experimental topology structure:
Purpose:
AREA0 is the backbone of the region, AREA1, AREA2 standard area
Ospf need to connect the region with the Central African Backbone backbone area, or can not communicate, but the interface to the backbone area is limited only by setting the virtual link before establishing communication is not connected with the backbone area.
Environment settings:
R1:
f0 / 0 (192.168.10.1/24)
f0 / 1 (192.168.20.1/24)
R2:
f0 / 0 (192.168.20.2/24)
f0 / 1 (192.168.30.1/24)
R3:
f0 / 0 (192.168.30.2/24)
f0 / 1 (192.168.40.1/24)
R4：
f0 / 0 (192.168.40.2/24)
f0 / 1 (192.168.50.1/24)
PC1：192.168.10.2/24
PC2：192.168.50.2/24
(A) R1 router configuration
R1#conf t 全局模式 Enter configuration commands, one per line. End with CNTL/Z. R1(config)#int f0/0 配置接口f0/0 R1(config-if)#ip add 192.168.10.1 255.255.255.0 R1(config-if)#no shut R1(config-if)#int f0/1 配置接口f0/1 R1(config-if)#ip add 192.168.20.1 255.255.255.0 R1(config-if)#no shut R1(config-if)#ex R1(config)#int loopback 0 设置本地的回环网卡固定IP R1(config-if)#ip add 1.1.1.1 255.255.255.255 R1(config-if)#no shut R1(config-if)#ex R1(config)#router ospf 1 设置ospf并宣告网段 R1(config-router)#router-id 1.1.1.1 R1(config-router)#network 192.168.10.0 0.0.0.255 area 2 R1(config-router)#network 192.168.20.0 0.0.0.255 area 2
（二）配置R2路由器
R2#conf t 全局模式 Enter configuration commands, one per line. End with CNTL/Z. R2(config)#int f0/0 配置f0/0接口 R2(config-if)#ip add 192.168.20.2 255.255.255.0 R2(config-if)#no shut R2(config-if)#int f0/1 配置f0/1接口 R2(config-if)#ip add 192.168.30.1 255.255.255.0 R2(config-if)#no shut R2(config-if)#ex R2(config)#int lo 0 设置本地的回环网卡固定IP R2(config-if)#ip add 2.2.2.2 255.255.255.255 R2(config-if)#no shut R2(config-if)#ex R2(config)#router ospf 1 设置ospf并宣告网段 R2(config-router)#router-id 2.2.2.2 R2(config-router)#network 192.168.20.0 0.0.0.255 area 2 R2(config-router)#network 192.168.30.0 0.0.0.255 area 1
（三）配置R3路由器
R3#conf t 全局模式 Enter configuration commands, one per line. End with CNTL/Z. R3(config)#int f0/0 配置接口f0/0 R3(config-if)#ip add 192.168.30.2 255.255.255.0 R3(config-if)#no shut R3(config-if)#int f0/1 配置接口f0/1 R3(config-if)#ip add 192.168.40.1 255.255.255.0 R3(config-if)#no shut R3(config-if)#ex R3(config)#int lo 0 配置本地的回环网卡固定IP R3(config-if)#ip add 3.3.3.3 255.255.255.255 R3(config-if)#no shut R3(config-if)#ex R3(config)#router ospf 1 设置ospf并宣告网段 R3(config-router)#router-id 3.3.3.3 R3(config-router)#network 192.168.30.0 0.0.0.255 area 1 R3(config-router)#network 192.168.40.0 0.0.0.255 area 0
（四）配置R4路由器
R4#conf t 全局模式 Enter configuration commands, one per line. End with CNTL/Z. R4(config)#int f0/0 配置f0/0接口 R4(config-if)#ip add 192.168.40.2 255.255.255.0 R4(config-if)#no shut R4(config-if)#int f0/1 配置f0/1接口 R4(config-if)#ip add 192.168.50.1 255.255.255.0 R4(config-if)#no shut R4(config-if)#ex R4(config)#int lo 0 设置本地回环网卡固定IP R4(config-if)#ip add 4.4.4.4 255.255.255.255 R4(config-if)#no shut R4(config-if)#ex R4(config)#router ospf 1 设置ospf并宣告网段 R4(config-router)#router-id 4.4.4.4 R4(config-router)#network 192.168.40.0 0.0.0.255 area 0 R4(config-router)#network 192.168.50.0 0.0.0.255 area 0
（五）配置PC1,PC2的地址和网关
pc1：
PC1> ip 192.168.10.2 192.168.10.1
pc2：
PC2> ip 192.168.50.2 192.168.50.1
(Vi) the test is not set virtual link, pc1 pc2 can ping
(Vii) disposed in virtual link R2 and R3
R2:
R2 (config) #router ospf 1 process into the ospf. 1 R2 (config-Router). 1 #area 3.3.3.3 Virtual Link Set-link to the virtual R3
R3:
R3 (config) #router ospf 1 process into the ospf. 1 R3 (config-Router). 1 #area 2.2.2.2 Virtual Link Set-link to the virtual R2
(H) At this point we can see two pc machine interoperability
OSPF backbone in the Central African region is not directly connected to the backbone area, we can achieve interoperability by providing a virtual link mode.
thanks for reading! ! !