! ==========================================
! Router R1 (Branch Edge Router & Dynamic PAT)
! Lab: IPv4 Dynamic PAT at the Edge (PTL-0020)
! ==========================================
enable
configure terminal
hostname R1

! LAN Interface (Inside NAT Domain)
interface GigabitEthernet0/0/0
 description Inside Private Branch LAN
 ip address 192.168.10.1 255.255.255.0
 ip nat inside
 duplex auto
 speed auto
 no shutdown
 exit

! WAN Interface (Outside NAT Domain)
interface GigabitEthernet0/0/1
 description Outside Uplink to ISP
 ip address 203.0.113.1 255.255.255.252
 ip nat outside
 duplex auto
 speed auto
 no shutdown
 exit

! Standard ACL matching internal private RFC 1918 branch subnet
access-list 1 permit 192.168.10.0 0.0.0.255

! Dynamic PAT (Overload) mapping inside hosts to outside public interface
ip nat inside source list 1 interface GigabitEthernet0/0/1 overload

! Default Route to simulated ISP Gateway
ip route 0.0.0.0 0.0.0.0 203.0.113.2

end
copy running-config startup-config