ZyXEL VMG1312-B10A VMG1312-B10A-EU01V1F Ficha De Dados

Chapter 11 Network Address Translation (NAT)

VMG1312-B10A User’s Guide

Some NAT routers may include a SIP Application Layer Gateway (ALG). A SIP ALG allows SIP calls 
to pass through NAT by examining and translating IP addresses embedded in the data stream. 
When the Device registers with the SIP register server, the SIP ALG translates the Device’s private 
IP address inside the SIP data stream to a public IP address. You do not need to use STUN or an 
outbound proxy if your Device is behind a SIP ALG.

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

Network Setting > NAT > ALG

The following table describes the fields in this screen.

Ordering your rules is important because the Device applies the rules in the order that you specify. 
When a rule matches the current packet, the Device takes the corresponding action and the 
remaining rules are ignored. 

Click Network Setting > NAT > Address Mapping to display the following screen. 

Network Setting > NAT > Address Mapping

Network Setting > NAT > ALG

NAT ALG

Enable this to make sure applications such as FTP and file transfer in IM applications work 
correctly with port-forwarding and address-mapping rules.

SIP ALG

Enable this to make sure SIP (VoIP) works correctly with port-forwarding and address-
mapping rules.

Apply

Click Apply to save your changes.

Cancel

Click Cancel to restore your previously saved settings.