Before discussing the configuration of the NAT in this article we will discuss the NAT advantages and disadvantages.
- The main advantage of NAT is that it can prevent the depletion of IPv4 addresses. It conserves the public IPv4 address by allowing the privatization of intranets. NAT save the addresses using application port-level multiplexing. With Port Address Translation, the hosts with private IPv4 addresses can share a single public IPv4 address for all external communications.
- Network Address Translation (NAT) also provides increased flexibility when connecting to the public Internet. We can implement a backup pool, and load-balancing pools to ensure reliable public network connections.
- If a network uses a public IP address, first the administrator will get an address space as a network grows, the chance of getting IP addresses from the same IP address class is minimal and even zero. But in case of using private address and NAT for external traffic using some addresses, an organization does not have to purchase IP addresses for every computer in use there is a significant cost saving due to using the process of Network Address Translation.
- Network Address Translation (NAT) allows to use your own private IPv4 addressing scheme and prevent the internal address changes in case of changing the service provider.
- Network Address Translation (NAT) provides additional security by masking the original source and destination addresses. The private networks do not advertise their addresses or internal topology, therefore, are secure when used in conjunction with NAT to gain controlled external access.
Disadvantages of NAT
With NAT advantages the NAT also some disadvantages. Because of the host on the Internet communicates directly with the NAT-enabled router in place of the actual host inside the private network. That situation creates several issues.
- Network Address Translation (NAT) consumes the processor and memory because NAT need to translate IPv4 addresses for all incoming and outgoing IPv4 datagram and to keep the translation details in memory.
- It slows down the network performance, therefore it creates a problem in real-time protocols. It increases switching delays because the translation of each IPv4 address within the packet headers takes time.
- When using, NAT the end-to-end addressing is lost. Several Internet protocols and applications basis on end-to-end addressing from the source to the destination therefore many applications do not work with NAT. Some applications use physical addresses, in its place of a qualified domain name, cannot reach the destinations when using a NAT router.
- In the case of using NAT, the end-to-end IPv4 traceability is not possible. The tracing of the packets is much difficult because of changing the address over multiple NAT hops. This makes troubleshooting difficult.
- NAT also make difficult the use of tunnelling