Port Address Translation (PAT) (Networking) | NAT vs PAT

 

Port Address Translation (PAT)

Port Address Translation (PAT), also known as NAT overload, is a type of Network Address Translation (NAT) that allows multiple devices on a local network (with private IP addresses) to share a single public IP address to access external networks, such as the internet.

In Port Address Translation (PAT), Private IP addresses are translated into the public IP address through port numbers. PAT also uses an IPv4 address but with a port number. It has two types:

1. Static
2. Overloaded PAT 

    Figure: Port Address Translation

Example:

Consider a home network with three devices: a computer, a smartphone, and a smart TV. Without PAT, each of these devices would need to have a unique public IP address to connect to the internet. However, with PAT, all of these devices can share a single public IP address and communicate with the internet by using unique port numbers. When the computer sends a request to the internet, PAT assigns it a unique port number and translates the private IP address of the computer into the public IP address of the network. The destination server on the internet receives the request and responds to the unique port number, allowing the computer to receive the response.

Differences between NAT and PAT are as follows :

Network Address Translation	Port Address Translation
NAT stands for Network Address Translation.	PAT stands for Port Address Translation.
In NAT, Private IP addresses are translated into the public IP address.	In PAT, Public IP addresses are translated into the public IP address via Port numbers.
NAT can be considered PAT’s superset.	PAT is a dynamic NAT.
NAT uses IPv4 address.	PAT also uses an IPv4 address but with a port number.