What is PAT (Port Address Translation) in Networking?

PAT (Port Address Translation) works very differently from Static and Dynamic NAT. This structure adds port numbers to the source portion of private IP addresses and matches them to global IP addresses. The most common type used in NAT is PAT.

What is PAT (Port Address Translation), One of the NAT Types?

In network environments, private IP addresses are used on the local network. Local private IP addresses cannot go directly to the Internet, and a public IP address assigned by the ISP is required for computers on the local network to access the Internet.

When you purchase an ADSL line for your home or office, your ISP usually provides an ADSL Modem. After setting up the Internet, your computers on the local network can access the Internet.

PCs on the LAN are subjected to NAT running effectively on ADSL Modems when going to the Internet.

In this article, we will talk about Port Address Translation, which is another type of NAT.

NAT and Port Address Translation

PAT is a different type of NAT and is also referred to as (NAT Overload).

Computers on the local network use NAT when going to the Internet. If the network environment belongs to a home user or a small business, the ADSL or Router is assigned the Global IP address assigned by the ISP.

You can configure individual computers in this network environment and bring them to the Internet with Static NAT. However, you can enable 254 computers or more with a single Global IP address by allowing NAT/PAT for a thriving network environment.

If you examine the image below, you can better understand NAT’s working logic.

Computers on the internal network are subjected to NAT processing while providing access to any website on the Internet.

How Does PAT Work?

The image above shows only the general operating logic of NAT. Now, let’s examine the network topology created in Cisco Packet Tracer.

The records in the image above are the NAT records created on Cisco Router0 when PC0 and PC1 ping Router1 at the same time.

As you can see, the IP addresses 192.168.10.10 and 192.168.10.20 have been converted to the IP address 10.0.0.1. Let’s say we created Dynamic NAT in this structure. Then, one of the two computers would not be able to ping. Plus, it would have to wait for the previous operation to finish.

The most significant advantage of PAT is that it can connect more than one computer to the Internet at the same time. It does this by matching port numbers with IP addresses. In this way, all computers on the network can access the Internet with a single Public IP address.

In addition, to enable PAT on Cisco Routers, an access list is first created, and the network is defined with the ip nat command.

Configuration ⇒ Video

If you’re wondering how to enable PAT on routers, you can watch the video below and also subscribe to our YouTube channel to support us!

Conclusion

The background system that runs while viewing a website at home or work is called PAT. With this feature, multiple devices can access the Internet at the same time. Thanks for following us!