ZyXEL Communications P-2900-4HB User Manual

 Chapter 6 Network Address Translation (NAT) Screens

P-2900-4HB User’s Guide

This section provides some technical background information about the topics 
covered in this chapter.

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)

Table 13   NAT Definitions

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.