How to configure nat overload in cisco router using packet tracer step by step guide

In this article we will  learn what is  nat overload(PAT), how to configure  nat overload in cisco router using packet tracer software.

Normally we use private ip inside the organization which is not allow to users to access the internet,then we use dynamic nat to fulfill our purpose. If ISP not provides organization pool of ip address then we go the another option which is called NAT overload(PAT).

Private ip address Range

Normally we use private ip address which is reserved inside the organization to communicate internal purpose which is not public ip address. The ange are given below.

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

Type of NAT

Three types of nats are available.

•   Static nat
•   Dynamicnat
•   Natoverloading(PAT)

What is NAT overload

In the dynamic nating we saw that ISP provides us a pool of public ip address to map with internal private ip to access internet. If ISP gives us few public ip addresses or 1 public ip address instead a pool of public ip addresses to map internal private ip addresses to access internet. In this scenario NAT overload is configured to overcome the problem.

Lab Diagram

                         How to configure nat overload in cisco router using packet tracer

In the above diagram we configure nat overload in cisco router using packet tracer software.

Configuration of NAT overload(PAT)

If ISP gives us few ip addresses or even 1 ip address so we can eliminate the netmask keyword from the dynamic nating command.

Router(config)#ip nat pool mypool 15.100.60.3 15.100.60.4

Router(config)#ip access-list extended mypool

Router(config-ext-nacl)#permit ip 192.168.1.0 0.0.0.255 any

Router(config-ext-nacl)#exit

Here we use only two public ip addesses to map with the internal private ip addresses.Finally we bind the access list with pool and use overload keyword end of the command.

Router(config)#ip nat pool inside source list mypool pool mypool overload

In this article we have   learned what is  nat overload(PAT), how to configure  nat overload in cisco router using packet tracer software.

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