How to Configurate NAT on Cisco 1941

Published on December 30 2013 by Emma lee

When you want to connect a local network to the Internet and you don’t have that much IP addresses.

There are two types of NAT that can be configured on a Cisco router, such as Cisco 2900

; static, and dynamic.

Static NAT Configuration:

This type is used when you want to do one-to-one assignment of local IP addresses to global IP addresses.

1. Establish static translation between an inside local address and an inside global address,

Router(config)#ip nat inside source static XXX.XXX.XXX.XXX YYY.YYY.YYY.YYY

where,

XXX.XXX.XXX.XXX is the (inside) local address

YYY.YYY.YYY.YYY is the (inside) global address

2. Specify the local interface. This is done by going to the interface configuration mode and issuing,

Router(config-if)#ip nat inside

3. Specify the global address. This is done by going to the interface configuration mode and issuing,

Router(config-if)#ip nat outside

Dynamic NAT Configuration:

This type is used when you want the router to do the mapping dynamically. This method is useful when you have too many global and local addresses and you do not want to do the mapping manually, or when the number of global addresses available is less than the local addresses.

This would lead us to two different scenarios,

A. The number of global IP addresses is equal or less than the local addresses and more than one. (global >= local >1)

1. Define a pool of global addresses that would be employed in the translation,

Router(config)#ip nat pool NAME XXX.XXX.XXX.XXX YYY.YYY.YYY.YYY netmask ZZZ.ZZZ.ZZZ.ZZZ

where,

NAME is the name of the pool

XXX.XXX.XXX.XXX is the starting IP address of the pool

YYY.YYY.YYY.YYY is the end IP address of the pool

ZZZ.ZZZ.ZZZ.ZZZ is the subnet mask of the network that the pool is part of.

Below are the details for the Cisco 1941 NAT configuration:

http://www.youtube.com/watch?v=Rs2tN6kAinU

It is refered from: www.routergeek.net/general