ZyXEL Communications LTE3301-PLUS, User Manual

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Chapter 11 Network Address Translation (NAT)
Nebula Mobile Router User’s Guide
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Figure 130 Network Setting > NAT > ALG
The following table describes the fields in this screen.
11.6 Technical Reference
This part contains more information regarding NAT.
11.6.1 NAT Definitions
Inside or 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 or 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 or 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 76 Network Setting > NAT > ALG
LABEL DESCRIPTION
SIP ALG Click this (switch turns blue) to make sure SIP (VoIP) works correctly with port-forwarding and
address-mapping rules. Otherwise, click this to turn off (switch turns gray) the SIP ALG.
PPTP ALG Click this to turn on (switch turns blue) the PPTP ALG on the Zyxel Device to detect PPTP traffic
and help build PPTP sessions through the Zyxel Device’s NAT.
Apply Click Apply to save your changes back to the Zyxel Device.
Cancel Click Cancel to restore your previously saved settings.
Table 77 NAT Definitions
ITEM DESCRIPTION
Inside This refers to the host on the LAN.
Outside This refers to the host on the WAN.
Local This refers to the packet address (source or destination) as the packet travels on the LAN.
Global This refers to the packet address (source or destination) as the packet travels on the WAN.