NAT Basics with need,types of nat,configuration and Advantages of nat

Posted: November 12, 2017 in Uncategorized
Tags: , ,

In this tutorial we will learn the basics of NAT like NAT introduction,Advantages of NAT,Disadvantages of NAT,Types of NAT and NAT configuration;

NAT stands for Network Address Translation. Bydefault Private IP Address can’t access internet because internet uses public ip address.So if you want to access internet from a private ip address you must configure NAT.
NAT is used to communicate public ip address with private ip address and vice versa.
NAT allows a single device like Router to act as a agent between the Internet and Local Network.
So all IP Address Translations take place at Router.

 

RANGE OF PRIVATE IP ADDRESS:

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)

NAT also ac as a typical firewall by hiding Internal IP Address from outer network.

ADVANTAGES OF NAT:

Public IP address sharing.
Easier expansion.
Greater Local Control.
Flexibility in ISP service.
Enhanced Security.
Mostly Transparent.

 

DISADVANTAGES OF NAT:

It’s complex to configure.
Lack of ip address creates problems.
Certain Applications are not compatible with NAT.
Problems with Security Protocol.
Poor support for client access.
Performance Reduction.
NON-NAT GIST nodes must be NAT aware.
Does not work in the presence of IPSec/TLS.

TYPES OF NAT:

There are total mainly Three types of NAT
1.Static NAT
2.Dynamic NAT(DNAT)
3.Port Address Translation(PAT)

 

But very few network engineers also beleive that NAT can be of below types:

NAT which modify only IP addresses.
NAT which modify IP addresses and POrt Numbers.
NAT that use a single IP Address.
NAT that Dynamically allocate IP Addresses to flows.

But if you are in ccna stage go with top 3 NAT i have mentioned above.

NAT CONFIGURATION:

If anyone want to configure NAT then atleast one interface on the router has to be configured with Inside Interface using below command.

Router>enable
Router#configure terminal
router(config)#ip nat inside

Use the IP Nat outside command to mark as interface as an outside interface.

Router>enable
Router#configure terminal
router(config)#ip nat inside

 

 Read:How to configure STATIC NAT on IPv4

Read:How to configuer STATIC NAT on IPv6

 

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