Wireless/Redundant Edge Services xl Module Management and Configuration Guide WS.02.xx and greater

8-10
Configuring Network Address Translation (NAT)
Overview
One principle to remember: on the Wireless Edge Services xl Module, you
define which VLANs are inside interfaces and which are outside. Figure 8-4
shows a configuration in which the VLAN used in the Ethernet network is an
outside interface. So you configure the destination NAT on inside interfaces
(these interfaces receive traffic that is destined to the outside VLAN).
As mentioned earlier, you can apply destination NAT to traffic from both the
inside and the outside network. In theory, you could also apply destination
NAT to traffic being sent from the wired network to the wireless network.
However, destination NAT is typically used to allow servers to share a public
IP address and to conceal their private addresses. Your wireless network is
unlikely to include such servers, so you would probably set up destination
NAT in one direction.
Using Port Forwarding with Static Destination NAT
The Wireless Edge Services xl Module also supports port forwarding for static
destination NAT. Port forwarding allows two or more devices on a network to
share a single IP address known in the other network. For example, you could
have wireless users send traffic that is destined to two different servers to the
same IP address:
■ your LAN’s Web server
■ your LAN’s FTP server
The Wireless Edge Services xl Module would then translate the destination IP
addresses of all traffic destined to port 80 to the Web server’s private IP
address (the address on wired network). Likewise, the module would translate
all traffic destined to port 21 to the FTP server’s private IP address.