ZyXEL Communications VMG8924-B10D - The ALG Screen

Chapter 11 Network Address Translation (NAT)
VMG8924-B10D/B30D User’s Guide
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Figure 81 Network Setting > NAT > DMZ
The following table describes the fields in this screen.
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 VMG
registers with the SIP register server, the SIP ALG translates the VMG’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 VMG is
behind a SIP ALG.
Use this screen to enable and disable the NAT and SIP (VoIP) ALG in the VMG. To access this screen,
click Network Setting > NAT > ALG.
Figure 82 Network Setting > NAT > ALG
The following table describes the fields in this screen.
Table 61 Network Setting > NAT > DMZ
LABEL DESCRIPTION
Default Server
Address
Enter the IP address of the default server which receives packets from ports that are not
specified in the NAT Port Forwarding screen.
Note: If you do not assign a Default Server Address, the VMG discards all packets
received for ports that are not specified in the NAT Port Forwarding screen.
Apply Click Apply to save your changes.
Cancel Click Cancel to restore your previously saved settings.
Table 62 Network Setting > NAT > ALG
LABEL DESCRIPTION
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.