Session-14/2 How to configure Static NAT | Network Address Translation configuration, Static NAT LAB
How to configure Static NAT, Network Address Translation configuration, Static NAT LAB,
NETWORK ADDRESS TRANSLATION
NAT is the method of Translation of private IP address into public IP address.
In order to communicate with internet, we must have registered public IP address.
Address translation was originally developed to solve two problems:
1. To handle a shortage of IPv4 addresses
2. Hide network addressing schemes.
* Small companies typically get their public IP addresses directly from their ISPs, which have a limited number.
* Large companies can sometimes get their public IP addresses from a registration authority, such as the Internet Assigned Numbers Authority (IANA).
* Common devices that can perform address translation include firewalls, routers, and servers. Typically address translation is done at the perimeter of the network by either a firewall (more commonly) or a router.
* There are certain addresses in each class of IP address that are reserved for Private Networks. These addresses are called private addresses.
Class A 10.0.0.0 to 10.255.255.255
Class B 172.16.0.0 to 172.31.255.255
Class C 192.168.0.0 to 192.168.255.255
Here’s a list of situations when it’s best to have NAT on your side:
* You need to connect to the Internet and your hosts don’t have globally unique IP addresses.
* You change to a new ISP that requires you to renumber your network.
* You need to merge two intranets with duplicate addresses.
Advantages
* Conserves legally registered addresses.
* Reduces address overlap occurrence. Increases flexibility when connecting to Internet.
* Eliminates address renumbering as network changes
Disadvantages
* Translation introduces switching path delays.
* Loss of end-to-end IP traceability.
* Certain applications will not function with NAT enabled.
NAT Terminology
Inside Local Addresses – Name of inside source address before translation (private IP)
Inside Global Address – Name of inside host after translation (public IP)
Outside Local Address – Name of destination host before translation
Outside Global Address – Name of outside destination host after translation
Types of NAT:-
1. Dynamic NAT
2. Static NAT
3. PAT
Static NAT
This type of NAT is designed to allow one-to-one mapping between local and global addresses.
Keep in mind that the static version requires you to have one real Internet IP address for every host on your network.
One-to-one mapping between the private address and the registered address
Every private IP needs one registered public IP address (one : one)
Defeats the goal of reducing the number of public IPv4 addresses needed for that organization
ip address
