Preparasi
1. Router ISP harus diberitahu bagaimana cara menjangkau alamat IP 209.165.200.254 (alamat IP public nya Server-PT)
RouterISP# ip route 209.165.200.254 255.255.255.255 209.165.200.225

2. Buat skema NAT di RouterNAT
Pertama, Static NAT
Usage: ip nat inside source static [ip private] [ip public]

RouterNAT# config t
RouterNAT(config)# interface f0/0
RouterNAT(config-if)# ip nat inside
RouterNAT(config-if)# interface f0/1
RouterNAT(config-if)# ip nat outside
RouterNAT(config-if)# exit
RouterNAT(config)# ip nat inside source static 192.168.20.1 209.165.200.254

Test NAT
Ping dari Server-PT ke Router ISP. Harusnya success/reply.

Kedua, Dynamic NAT
Usage: ip nat pool [name-pool] [ip public-ip public] netmask []
Preparasi
Disini, perusahaan XYZ membeli 4 buah IP public dari service provider (209.165.200.241 - 209.165.200.246). Router ISP harus dikonfigurasi bagaimana cara untuk mencapai 4 IP public ini
RouterISP# no ip route 209.165.200.254 255.255.255.255 209.165.200.225
RouterISP# ip route 209.165.200.240 255.255.255.252 209.165.200.225

Mulai mengkonfigurasi NAT
RouterNAT# config t
RouterNAT(config)# no ip nat inside source static 192.168.20.1 209.165.200.254
RouterNAT(config)# ip nat pool MY-NAT-POOL 209.165.200.241 209.165.200.246 netmask 255.255.255.240

RouterNAT(config)# ip access-list standard NAT
RouterNAT(config-std-nacl)# permit 192.168.20.0 0.0.0.255
RouterNAT(config-std-nacl)# exit

RouterNAT(config)# ip nat inside source list NAT pool MY-NAT-POOL

RouterNAT(config)# interface f0/0
RouterNAT(config-if)# ip nat inside
RouterNAT(config-if)# interface f0/1
RouterNAT(config-if)# ip nat outside

Test NAT
Ping dari Server-PT ke Router ISP. Harusnya success/reply.

Ketiga, Dynamic NAT dengan command overload
RouterNAT(config)# no ip nat inside source list NAT pool MY-NAT-POOL
RouterNAT(config)# ip nat nat inside source list NAT pool MY-NAT-POOL overload

Selamat, anda telah berhasil membuat NAT!