WESM zl Management and Configuration Guide WT.01.28 and greater

8-9
Configuring Network Address Translation (NAT)
Overview
One principle to remember: on the Wireless Edge Services zl 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 zl 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 zl 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.