ZyXEL g-2000 plusv2 Guia Do Utilizador

ZyXEL G-2000 Plus v2 User’s Guide

Chapter 8 Single User Account (SUA) / Network Address Translation (NAT)

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This chapter discusses how to configure SUA/NAT on the ZyXEL device.

NAT (Network Address Translation - NAT, RFC 1631) is the translation of the IP address of a 
host in a packet. For example, the source address of an outgoing packet, used within one 
network is changed to a different IP address known within another network. 

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.