实验拓扑图：
思科：
R1：
interface F1/0
ip address 192.168.1.1 255.255.255.255
no shutdown
interface F0/0
ip address 192.168.2.1 255.255.255.255
no shutdown
ip route 192.168.3.0 255.255.255.0 192.168.2.2
ip route 192.168.4.0 255.255.255.0 192.168.2.2
show ip interface brief
show ip route
R2：
interface F0/0
ip address 192.168.2.2 255.255.255.255
no shutdown
interface F1/0
ip address 192.168.3.2 255.255.255.255
no shutdown
ip route 192.168.1.0 255.255.255.0 192.168.2.1
ip route 192.168.4.0 255.255.255.0 192.168.3.3
show ip interface brief
show ip route
R3：
interface F0/0
ip address 192.168.3.3 255.255.255.0
no shutdown
interface F1/0
ip address 192.168.4.3 255.255.255.0
no shutdown
ip route 0.0.0.0 0.0.0.0 192.168.3.2（使用默认路由，或者静态路由：ip route 192.168.2.0 255.255.255.0 192.168.3.2 ip route 192.168.1.0 255.255.255.0 192.168.3.2 ）
show ip interface brief
show ip route
华为：
R1：
interface F1/0
ip address 192.168.1.1 24
undo shutdown
interface F0/0
ip address 192.168.2.1 24
undo shutdown
ip route-static 192.168.3.0 24 192.168.2.2
ip route-static 192.168.4.0 24 192.168.2.2
display ip interface brief
display ip routing-table
R2：
interface F0/0
ip address 192.168.2.2 24
undo shutdown
interface F1/0
ip address 192.168.3.2 24
undo shutdown
ip route-static 192.168.1.0 24 192.168.2.1
ip route-static 192.168.4.0 24 192.168.3.3
display ip interface brief
display ip routing-table
R3：
interface F0/0
ip address 192.168.3.3 24
undo shutdown
interface F1/0
ip address 192.168.4.3 24
undo shutdown
ip route-static 0.0.0.0 0 192.168.3.2（使用默认路由，或者静态路由：ip route 192.168.2.0 24 192.168.3.2 ip route 192.168.1.0 24 192.168.3.2 ）
display ip interface brief
display ip routing-table