There are two types of
NAT that can be configured on a Cisco router Cisco 3925E; 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:
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http://www.youtube.com/watch?v=Rs2tN6kAinU
It is refered from: www.routergeek.net/general.
