User's Manual

Chapter 9 Network Address Translation (NAT)

AMG1202-T10A User’s Guide

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ZyXEL Device keeps track of the original addresses and port numbers so incoming reply packets can

have their original values restored. The following figure illustrates this.

Figure 71 How NAT Works

9.6.4 NAT Application

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

using IP alias) behind the ZyXEL Device can communicate with three distinct WAN networks.

Figure 72 NAT Application With IP Alias

9.6.5 NAT Mapping Types

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

192.168.1.13

192.168.1.10

192.168.1.11

192.168.1.12

192.168.1.10

IGA1

Inside Local

IP Address

192.168.1.10

192.168.1.11

192.168.1.12

192.168.1.13

Inside Global

IP Address

IGA 1

IGA 2

IGA 3

IGA 4

NAT Table

WAN

LAN

Inside Local

Address (ILA)

Inside Global

Address (IGA)