Dynamic Nat is useful in a larger network where one public IP is not sufficient to fulfill the requirement of an organization. In the Dynamic Nat, we can create a pool of public IP addresses that will be used for the NAT translations.

Dynamic Nat is same as the normal Nat – the only difference is that the Dynamic Nat uses a pool of public IP addresses for the Nat translation. And the IP addresses from the pool are dynamically selected for the translation.

We have to label the router interface with IP Nat inside and IP Nat outside, and create an access list to permit a range of IPs to be translated. Then, we have to create a pool of public IP addresses, which are given by the ISP. And finally, we have to allow the private IPs to be translated dynamically with the pool of public IP addresses. To enable Pat with the Dynamic Nat, we have to type ‘overload’ at the end.

Dynamic NAT configuration commands

DOWNLOAD

Lab Tasks

1. label the interfaces
2. create a access list to allow network 192.168.1.0/24 to be translated
3. create a pool of public IP addresses from 117.45.23.2 to 117.45.23.5
4. Enable NAT with PAT

Lab Configuration

 Task 1

Router(config)#interface fastethernet 0/0

Router(config)#ip nat inside

Router(config)#interface fastethernet 0/1

Router(config)#ip nat outside

Task 2

Router(config)#access-list 1 permit 192.168.1.0 0.0.0.255

Task 3

Router(config)#ip nat pool public-ips 117.45.23.2 117.45.23.5 netmask 255.255.255.0

Task 4

Router(config)#ip nat inside source list 1 pool public-ips overload