Specifications

3-3
Cisco 1700 Series Router Software Configuration Guide
78-5407-03
Chapter 3 Miscellaneous Features
Configuring Network Address Translation
dns-server 172.16.1.102 172.16.2.102
netbios-name-server 172.16.1.103 172.16.2.103
netbios-node-type h-node
!
ip dhcp pool 1
network 172.16.1.0 /24
default-router 172.16.1.100 172.16.1.101
lease 30
!
ip dhcp pool 2
network 172.16.2.0 /24
default-router 172.16.2.100 172.16.2.101
lease 30
Configuring Network Address Translation
Network Address Translation (NAT) translates IP addresses within private
“internal” networks to “legal” IP addresses for transport over public “external”
networks (such as the Internet). Incoming traffic is translated back for delivery
within the inside network. Thus, NAT allows an organization with unregistered
“private” addresses to connect to the Internet by translating those addresses into
globally registered IP addresses.
Interfaces are configured as “NAT inside” or “NAT outside.” Once the interfaces
are configured, the following steps can be performed to establish the NAT
configuration within the router.
Command Task
Step1
ip nat pool name start-ip end-ip {netmask
netmask | prefix-length prefix-length}
Create a pool of global IP addresses for NAT.
Step2
access-list access-list-number permit source
[source-wildcard]
Define a standard access list permitting
addresses that need translation.
Step3
ip nat inside source list access-list-number
pool name [overload]
Enable dynamic translation of addresses
permitted by access list. Overload allows the
use of one global address, from the pool, for
many local addresses.
Step4
ip nat outside source static global-ip
local-ip
Enable static translation of a specified outside
source address. This command is optional.