ZyXEL Communications P-2612HW-F1 -, User Manual

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Chapter 9 Network Address Translation (NAT)
P-2612HW Series User’s Guide
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Use this screen to enable and disable the SIP (VoIP) ALG in the ZyXEL Device. To
access this screen, click Network > NAT > ALG.
Figure 116 Network > NAT > ALG
Each field is described in the following table.
9.5 NAT Technical Reference
This section provides some technical background information about the topics
covered in this chapter.
9.5.1 NAT Definitions
Inside/outside denotes where a host is located relative to the ZyXEL Device, for
example, the computers of your subscribers are the inside hosts, while the web
servers on the Internet are the outside hosts.
Global/local denotes the IP address of a host in a packet as the packet traverses a
router, for example, the local address refers to the IP address of a host when the
packet is in the local network, while the global address refers to the IP address of
the host when the same packet is traveling in the WAN side.
Note that inside/outside refers to the location of a host, while global/local refers to
the IP address of a host used in a packet. Thus, an inside local address (ILA) is the
IP address of an inside host in a packet when the packet is still in the local
network, while an inside global address (IGA) is the IP address of the same inside
Table 49 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 ZyXEL Device.
Reset Click this to return to previously saved configuration.