Cable Router User's Guide

Chapter 6 Network Address Translation (NAT) Screens
P-2900-4HB User’s Guide
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6.3 NAT Technical Reference
This section provides some technical background information about the topics
covered in this chapter.
6.3.1 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.
NAT never changes the IP address (either local or global) of an outside host.
Apply Click Apply to save your changes back to the ZyXEL Device.
Cancel Click Cancel to return to the previously saved settings.
Delete Click Delete to exit this screen without saving.
Table 12 Edit Address Mapping Rule (continued)
LABEL DESCRIPTION
Table 13 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.