Configure NAT overload by using the
keyword overload:
Router(config)#ip nat inside
source list access-list-number pool name overload
RTA is configured as shown here:
RTA(config)#ip nat pool
mypatpool 171.70.2.1 171.70.2.30 netmask 255.255.255.0
RTA(config)#access-list 24 permit 10.1.1.0 0.0.0.255
RTA(config)#ip nat inside source list 24 pool mypatpool overload
RTA(config)#interface bri 0
RTA(config-if)#ip nat outside
RTA(config-if)#interface ethernet 0
RTA(config-if)#ip nat inside
The
ip nat pool
command creates the pool of
addresses that are used for overloading. Notice that this pool, mypatpool,
contains only 30 addresses. Using NAT overload, these 30 addresses
can comfortably serve hundreds, or even thousands, of inside hosts
(see Figure ).
The
access-list
command creates the access list
that is used to match addresses that are to be translated. The
ip nat inside source list 24
command configures the router to
translate addresses that match access list 24 using inside global
addresses from mypatpool.
You do not necessarily have to configure an address pool in
order for NAT overload to work. If you don't have any available IP
addresses, you can overload the address of the outside interface, as
shown:
Router(config)#ip nat inside
source list access-list-number interface interface-name
overload
Typically, home users receive only one IP address by their
provider. Figure
shows how NAT overload can be configured using the outside
interface.
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