Nat Technical Reference; Nat Definitions - ZyXEL Communications P-660H-61 User Manual

Use this screen to enable and disable the SIP (VoIP) ALG in the ZyXEL Device. To access this
screen, click Network > NAT > ALG.
Figure 67 Network > NAT > ALG
The following table describes the fields in this screen.
Table 46 Network > NAT > ALG
LABEL
Enable SIP ALG
Apply
Reset

9.6 NAT Technical Reference

This chapter contains more information regarding NAT.

9.6.1 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 host when the packet is on the WAN side. The following table
summarizes this information.
Table 47 NAT Definitions
ITEM
Inside
Outside
ADSL Router Series User's Guide
DESCRIPTION
Select this to make sure SIP (VoIP) works correctly with port-forwarding and address-
mapping rules.
Click this to save your changes.
Click this to restore your previously saved settings.
DESCRIPTION
This refers to the host on the LAN.
This refers to the host on the WAN.
Chapter 9 Network Address Translation (NAT)
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