1. 配置接口的IP地址
[AR1-GigabitEthernet0/0/0]ip add 20.1.1.1 24
[AR1-GigabitEthernet0/0/1]ip add 10.1.1.1 24
[AR2-GigabitEthernet0/0/0]ip add 20.1.1.2 24
[AR2-GigabitEthernet0/0/1]ip add 30.1.1.2 24
[AR3-GigabitEthernet0/0/0]ip add 30.1.1.3 24
[AR3-GigabitEthernet0/0/1]ip add 10.2.1.3 24
2. 配置设备间使用OSPF路由
[AR1]ospf 1
[AR1-ospf-1]area 0
[AR1-ospf-1-area-0.0.0.0]network 20.1.1.0 0.0.0.255
[AR2]ospf 1
[AR2-ospf-1]area 0
[AR2-ospf-1-area-0.0.0.0]network 20.1.1.0 0.0.0.255
[AR2-ospf-1-area-0.0.0.0]network 30.1.1.0 0.0.0.255
[AR3]ospf 1
[AR3-ospf-1]area 0
[AR3-ospf-1-area-0.0.0.0]network 30.1.1.0 0.0.0.255
3. 配置Tunnel接口
[AR1]int Tunnel 0/0/1
[AR1-Tunnel0/0/1]tunnel-protocol gre
[AR1-Tunnel0/0/1]ip add 40.1.1.1 24
[AR1-Tunnel0/0/1]source 20.1.1.1
[AR1-Tunnel0/0/1]destination 30.1.1.3
[AR1-Tunnel0/0/1]keepalive //为了能够检测隧道链路状态,还可以在GRE隧道两端的Tunnel接口上使能Keepalive功能
[AR3]int Tunnel 0/0/1
[AR3-Tunnel0/0/1]tunnel-protocol gre
[AR3-Tunnel0/0/1]ip add 40.1.1.3 24
[AR3-Tunnel0/0/1]source 30.1.1.3
[AR3-Tunnel0/0/1]destination 20.1.1.1
[AR3-Tunnel0/0/1]keepalive
Tunnel接口之间可以Ping通,直连隧道建立
4. 配置Tunnel接口使用OSPF路由
[AR1]ospf 2
[AR1-ospf-2]area 0
[AR1-ospf-2-area-0.0.0.0]network 10.1.1.0 0.0.0.255
[AR1-ospf-2-area-0.0.0.0]network 40.1.1.0 0.0.0.255
[AR3]ospf 2
[AR3-ospf-2]area 0
[AR3-ospf-2-area-0.0.0.0]network 40.1.1.0 0.0.0.255
[AR3-ospf-2-area-0.0.0.0]network 10.2.1.0 0.0.0.255
5. 检查配置