The Alg Screen; The Address Mapping Screen - ZyXEL Communications VMG1312-B Series User Manual

Chapter 11 Network Address Translation (NAT)

11.6 The ALG Screen

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.
Figure 81 Network Setting > NAT > ALG
The following table describes the fields in this screen.
Table 58 Network Setting > NAT > ALG
LABEL
NAT ALG
SIP ALG
Apply
Cancel

11.7 The Address Mapping 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.
Figure 82 Network Setting > NAT > Address Mapping
192
DESCRIPTION
Enable this to make sure applications such as FTP and file transfer in IM applications work
correctly with port-forwarding and address-mapping rules.
Enable this to make sure SIP (VoIP) works correctly with port-forwarding and address-
mapping rules.
Click Apply to save your changes.
Click Cancel to restore your previously saved settings.
VMG1312-B Series User's Guide