Installation guide

WF200 802.11g Wireless Router

Outside This refers to the host on the WAN.

Local This refers to the packet address (source or destination) as the packet travels on the

LAN.

Global This refers to the packet address (source or destination) as the packet travels on the

WAN.

6.3.2 How NAT Works

Each packet has two addresses – a source address and a destination address. For outgoing packets, the

ILA is the source address on the LAN, and the IGA is the source address on the WAN. For incoming

packets, the ILA is the destination address on the LAN, and the IGA is the destination address on the

WAN. NAT maps private (local) IP addresses to globally unique ones required for communication with

hosts on other networks. It replaces the original IP source address (and TCP or UDP source port

numbers for Many-to-One and Many-to-Many Overload NAT mapping) in each packet and then

forwards it to the Internet. The ROUTER keeps track of the original addresses and port numbers so

incoming reply packets can have their original values restored.

The following figure illustrates this.

6.3.3 NAT Application

The following figure illustrates a possible NAT application, where three inside LANs (logical LANs

using IP Alias) behind the router can communicate with three distinct WAN networks. More examples

follow at the end of this chapter.

6.3.4 NAT Mapping Types

NAT supports five types of IP/port mapping. They are:

a. One-to-One: In One-to-One mode, the device maps one local IP address to one global IP address.

b. Many-to-One: In Many-to-One mode, the device maps multiple local IP addresses to one global IP