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?
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, an ADSL Modem is usually provided by your ISP. 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 enabling 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 It 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 above image are NAT records that occur on Cisco Router0 when PC0 and PC1 simultaneously ping Router1.
As you can see, the 192.168.10.10 and 192.168.10.20 IP addresses converted to the 10.0.0.1 IP address. If Dynamic NAT has created in this structure, one of the two computers would not be able to Ping and wait for the previous process to finish.
The biggest advantage of PAT is that multiple computers can access the Internet at the same time. This is done by matching the Port numbers to the IP addresses, so that all computers on the network can access the Internet with a single Public IP address.
In addition, to enable it 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!
The name of the system that runs in the background while viewing a website at home or at work is PAT. With this feature, multiple devices can access the Internet at the same time. Thanks for following us!