pc1 en conf t no ip routing int f0/0 ip add 192.168.10.10 255.255.255.0 no shut exit ip default-gateway 192.168.10.254 pc2 en conf t no ip routing int f0/0 ip add 192.168.20.20 255.255.255.0 no shut exit ip default-gateway 192.168.20.254 R1 en conf t int f0/0 ip add 192.168.10.254 255.255.255.0 no shut int f1/0 ip add 10.10.10.1 255.255.255.252 no shut exit R2 en conf t int f0/0 ip add 10.10.10.2 255.255.255.252 no shut int f1/0 ip add 20.20.20.1 255.255.255.252 no shut exit R3 en conf t int f0/0 ip add 192.168.20.254 255.255.255.0 no shut int f1/0 ip add 20.20.20.2 255.255.255.252 no shut exit