Chapter 10 Network Address Translation (NAT)
VMG8324-B10A / VMG8324-B30A Series User’s Guide
166
10.6
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 91
Network Setting > NAT > ALG
The following table describes the fields in this screen.
10.7
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 92
Network Setting > NAT > Address Mapping
Table 64
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.
RTSP ALG
Enable this to have the Device detect RTSP traffic and help build RTSP sessions through its
NAT. The Real Time Streaming (media control) Protocol (RTSP) is a remote control for
multimedia on the Internet.
Apply
Click
Apply
to save your changes.
Cancel
Click
Cancel
to restore your previously saved settings.