配置Router1路由器：
hostname R1
interface fa 0/1
ip add 10.1.2.1 255.255.255.0
exit
interface loopback 0
ip add 192.168.3.1 255.255.255.0
exit
router ospf 1
network 192.168.3.0 0.0.0.255 area 0
network 10.1.2.0 0.0.0.255 area 0
配置Router3：
hostname R3
interface fa 0/1
ip add 10.1.1.2 255.255.255.0
exit
interface loopback 0
ip add 192.168.1.1 255.255.255.0
exit
router rip
version 2
network 192.168.1.1
network 10.1.1.0
no auto-summary
配置Router2：
hostname R2
interface fa 0/0
ip add 10.1.2.2 255.255.255.0
exit
interface fa 0/1
ip add 10.1.1.1 255.255.255.0
exit
int loopback 0
ip add 192.168.2.1 255.255.255.0
exit
router ospf 1
network 192.168.2.0 0.0.0.255 area 0
network 10.1.2.0 0.0.0.255 area 0
redistribute rip subnets
default-information originate (设置默认路由)
exit
router rip
version 2
no auto-summary
network 10.1.1.0
redistribute ospf 1
exit
ip route 0.0.0.0 0.0.0.0 10.1.1.2
exit
配置完成后用以下命令查验：
show ip route
show running-config