R1：
system-view
Int g0/0/0
Ip add 192.168.1.1 24
Int g0/0/1
Ip add 12.1.1.1 24
Ip route-static 192.168.2.0 24 12.1.1.2
R2:
system-view
Int g0/0/0
Ip add 12.1.1.2 24
Int g0/0/1
Ip add 23.1.1.2 24
Ip route-s 192.168.2.0 24 23.1.1.3
Ip route-s 192.168.1.0 24 12.1.1.1
R3:
system-view
Int g0/0/0
Ip add 23.1.1.3 24
Int g0/0/1
Ip add 192.168.2.1 24
Ip route-s 192.168.1.0 24 23.1.1.2