Configure Network Address Translation - Cisco CISCO851-K9 - 851 Integrated Services Router Configuration Manual

Configure Network Address Translation

Configure Network Address Translation
Network Address Translation (NAT) translates packets from addresses that match a standard access list,
using global addresses allocated by the dialer interface. Packets that enter the router through the inside
interface, packets sourced from the router, or both are checked against the access list for possible address
translation. You can configure NAT for either static or dynamic address translations.
Perform these steps to configure the outside Fast Ethernet WAN interface with dynamic NAT, beginning
in global configuration mode:
Command
Step 1 ip nat pool name start-ip end-ip {netmask
netmask | prefix-length prefix-length}
Example:
Router(config)# ip nat pool pool1
192.168.1.0 192.168.2.0 netmask
255.255.252.0
Router(config)#
Step 2 ip nat inside source {list access-list-number}
{interface type number | pool name} [overload]
Example 1:
Router(config)# ip nat inside source list 1
interface dialer 0 overload
or
Example 2:
Router(config)# ip nat inside source list
acl1 pool pool1
Step 3 interface type number
Example:
Router(config)# interface vlan 1
Router(config-if)#
Step 4 ip nat {inside | outside}
Example:
Router(config-if)# ip nat inside
Router(config-if)#
Cisco 850 Series and Cisco 870 Series Access Routers Software Configuration Guide
3-6
Chapter 3 Configuring PPP over Ethernet with NAT
Purpose
Creates pool of global IP addresses for NAT.
Enables dynamic translation of addresses on the
inside interface.
The first example shows the addresses permitted
by the access list 1 to be translated to one of the
addresses specified in the dialer interface 0.
The second example shows the addresses
permitted by access list acl1 to be translated to one
of the addresses specified in the NAT pool pool1.
For details about this command and additional
parameters that can be set, as well as information
about enabling static translation, see the
Cisco IOS IP Command Reference, Volume 1 of 4:
Addressing and Services.
Enters configuration mode for the VLAN (on
which the Fast Ethernet LAN interfaces
[FE0–FE3] reside) to be the inside interface for
NAT.
Identifies the specified VLAN interface as the
NAT inside interface.
For details about this command and additional
parameters that can be set, as well as information
about enabling static translation, see the
Cisco IOS IP Command Reference, Volume 1 of 4:
Addressing and Services.
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