User's Manual

Configuring Network Address Translation
308625-14.00 Rev 00
2-35
Modifying the Interface Type
The NAT router is configured with local and global interfaces. Local interfaces are
attached to the local network. When a packet arrives at the local interface, the
NAT router examines the packet’s source address to determine whether it should
be translated into a global address before forwarding. Global interfaces are
attached to the external network. When a packet arrives at the global interface, the
NAT router examines the packet’s destination address to determine whether it is
an existing translation.
By default, when you enable NAT on an IP interface, the interface type is set to
local. To configure an external interface, you must set the type to global.
Using the BCC
To modify the NAT interface type, navigate to the NAT interface prompt (for
example,
box; ethernet/13/1; ip1.2.3.4/255.0.0.0; nat
) and enter:
type
<type>
type
is one of the following:
local
(default)
global
For example, the following command sequence changes the type for NAT
interface 197.1.2.3 from local to global and verifies the change:
standard/5/1#
ip 197.1.2.3/8
ip/197.1.2.3/255.0.0.0#
nat
nat/197.1.2.3#
info
type local
state enabled
nat/197.1.2.3#
type global
nat/197.1.2.3#
info
type global
state enabled