1. Network Topology Overview
| Element | Details |
|---|---|
| Inside Local | 192.168.1.0/24 |
| Inside Global Pool | 203.0.113.20 — 203.0.113.30 |
| Interfaces | Gi0/0 (Inside), Gi0/1 (Outside) |
2. Basic Interface Configuration
Define the boundaries of your NAT domain.
Router CLI
Router(config)#interface GigabitEthernet0/0 Router(config-if)#ip address 192.168.1.1 255.255.255.0 Router(config-if)#ip nat inside Router(config-if)#exit Router(config)#interface GigabitEthernet0/1 Router(config-if)#ip address 203.0.113.1 255.255.255.0 Router(config-if)#ip nat outside Router(config-if)#exit
3. Dynamic NAT Configuration
Mapping a group of local addresses to a pool of global addresses.
Router CLI
! Define the public pool Router(config)#ip nat pool MY_POOL 203.0.113.20 203.0.113.30 netmask 255.255.255.0 ! Define traffic to be translated Router(config)#access-list 1 permit 192.168.1.0 0.0.0.255 ! Bind them together Router(config)#ip nat inside source list 1 pool MY_POOL
4. PAT (Port Address Translation)
Commonly known as NAT Overload, this allows multiple hosts to share one IP.
Note
Most modern networks use PAT to conserve IPv4 addresses.
Most modern networks use PAT to conserve IPv4 addresses.
Router CLI
! Overload using the outside interface IP Router(config)#ip nat inside source list 1 interface GigabitEthernet0/1 overload
5. Verification
Use these commands to check if traffic is flowing and translating correctly.
Verification Commands
Router#show ip nat translations Router#show ip nat statistics