ZyXEL Communications Corporation AMG1302 Manuel D’Utilisation

Chapter 9 Network Address Translation (NAT)

AMG1302-T10A User’s Guide

Use this screen to enable and disable the SIP (VoIP) ALG in the Device. To access this screen, click 
Network > NAT > ALG

.

Network > NAT > ALG

The following table describes the fields in this screen.

This chapter contains more information regarding NAT.

Inside/outside denotes where a host is located relative to the Device, for example, the computers 

of your subscribers are the inside hosts, while the web servers on the Internet are the outside 

hosts. 

Global/local denotes the IP address of a host in a packet as the packet traverses a router, for 

example, the local address refers to the IP address of a host when the packet is in the local 

network, while the global address refers to the IP address of the host when the same packet is 

traveling in the WAN side. 

Note that inside/outside refers to the location of a host, while global/local refers to the IP address 

of a host used in a packet. Thus, an inside local address (ILA) is the IP address of an inside host in 

a packet when the packet is still in the local network, while an inside global address (IGA) is the IP 

address of the same inside host when the packet is on the WAN side. The following table 

summarizes this information.

Network > NAT > ALG

Enable SIP ALG

Select this to make sure SIP (VoIP) works correctly with port-forwarding and address-

mapping rules.

Apply

Click this to save your changes.

Reset

Click this to restore your previously saved settings.

NAT Definitions

Inside

This refers to the host on the LAN.

Outside

This refers to the host on the WAN.