ZyXEL Communications P-3202HN-Ba, User Manual

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Chapter 9 Network Address Translation (NAT)
IAD User’s Guide
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9.5 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 IAD registers with the SIP register server,
the SIP ALG translates the IAD’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 IAD
is behind a SIP ALG.
Use this screen to enable and disable the SIP (VoIP) ALG in the IAD. To access this
screen, click Network > NAT > ALG.
Figure 48 Network > NAT > ALG
Each field is described in the following table.
Server
Mapping Set Only available when Type is set to Server.
Select a number from the drop-down menu to choose a port forwarding
set.
Edit Details Click this link to go to the Port Forwarding screen to edit a port
forwarding set that you have selected in the Server Mapping Set field.
Back Click Back to return to the previous screen.
Apply Click Apply to save your changes to the IAD.
Cancel Click Cancel to begin configuring this screen afresh.
Table 30 Network > NAT > Address Mapping: Edit (continued)
LABEL DESCRIPTION
Table 31 Network > NAT > ALG
LABEL DESCRIPTION
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 and to apply them to the IAD.
Reset Click this to return to previously saved configuration.