The Functions of NAT (Network Address Translation)

Network Address Translation (NAT) is a technique to convert one IP address into another.

This article explains the NAT and its functions in detail. We will also check the importance of Network Address Translation and how it helps in our daily life.

Let us check the primary functions of the Network Address Translation.

1. NAT helps to share a single Internet connection among multiple devices in a network.

2. NAT acts as a barrier between external elements and our internal network.

Now let us check how NAT helps a regular person in daily life.

Assume you have two laptops, two smartphones, and a desktop computer in your home. You have a Cox Internet connection and a Belkin wireless router. The home network is simple. You connect the Belkin router to the Cox modem and all devices to the Belkin router.

Have a look at the diagram below.

A single public IP address converts into multiple private IP addresses.

Network Address Translation is of different types depending on the way and the number of IP addresses they translate.

1. Static NAT

   In Static Network Address Translation, one IP address in a packet is translated to a different IP address manually. It is a one-to-one mapping.

   
   
   

2. Dynamic NAT

   In Dynamic Network Address Translation, the address translation device picks an IP address dynamically to convert from a list of allowed IP addresses.

   Dynamic NAT has two sets of IP addresses.

   One is a list of IP addresses that get converted, and the second is the list of IP addresses as the final IP addresses.

   Let us check the advantages and disadvantages of Dynamic Network Address Translation.

   The major problem with static and dynamic NAT is they convert just one IP address to another IP address.

   It cannot convert multiple IP addresses to a public IP address or vice versa.

   
   
   

3. Port Address Translation

   Port Address Translation (PAT) helps all the private IP addresses in the network to use a single public IP address with different port numbers.

   So by using PAT, we overcome the limitation of NAT that uses one-to-one mapping.

   PAT works with only TCP and UDP protocols.

   PAT is not free from disadvantages. Not all applications work with PAT.

   
   
   

4. Port Address Redirection

   Port Address Redirection (PAR) is the reverse of PAT. In PAR, multiple public IP addresses convert to a single private IP address.

   PAR works with only TCP and UDP protocols.

   However, Port Address Redirection also does not work with all applications.

   
   

1. Address Translation fixed the scarcity of IP addresses
   
   
2. NAT successfully hides internal network design from external parties
   
   
3. NAT helps network admins to have tighter control over network traffic

Though NAT is helpful, it is not free from disadvantages. Some of them are:

1. PAT and PAR work with only TCP and UDP protocols.
   
   
2. Not all applications support Address Translation.
   
   
3. Address Translation causes an extra delay in each connection.
   
   
4. NAT makes network troubleshooting more complex.

1. Dynamic Host Configuration Protocol (DHCP)
   
   
2. OSI Reference Model
   
   
3. Virtual Router Redundancy Protocol (VRRP)
   
   
4. What is a Router & Major Routing Protocols