Router1 F1/1 <----> Switch1 F0/0
Router1 S2/0 <----> Router2 S1/0
Switch1 F0/2 <----> VPCS V0/2
www:172.15.1.2/24 172.15.1.1
pc:192.168.1.2/24 192.168.1.1
s2/0:172.16.1.1/24
s1/0:172.16.1.2/24
RA(config)#ip route 0.0.0.0 0.0.0.0 172.16.1.2
RA(config)#interface s2/0
RA(config-if)#ip nat outside
RA(config-if)#exit
RA(config)#interface f1/0
RA(config-if)#ip nat inside
RA(config)#ip nat pool apple 172.15.1.10 172.15.1.100 netmask 255.255.255.0
RA(config)#ip nat inside source list 1 pool apple overload
RA(config-if)#interface f1/1
RA(config-if)#ip nat inside
RA(config-if)#interface s2/0
RA(config-if)#ip nat outside
RA(config)#ip nat inside source list 1 interface s2/0 overload
RA(config)#interface s2/0
RA(config-if)#ip nat outside
RA(config-if)#interface f1/1
RA(config-if)#ip nat inside