ZyXEL 202H 91-003-194003B User Manual

P-202H Plus v2 User’s Guide

Chapter 6 Network Address Translation (NAT) Screens

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The following figure illustrates a possible NAT application, where three inside LANs (logical 
LANs using IP alias) behind the ZyXEL Device can communicate with three distinct WAN 
networks. More examples follow at the end of this chapter.

Figure 19   NAT Application With IP Alias

NAT supports five types of IP/port mapping. They are:

• One to One: In One-to-One mode, the ZyXEL Device maps one local IP address to one 

global IP address.

• Many to One: In Many-to-One mode, the ZyXEL Device maps multiple local IP 

addresses to one global IP address. This is equivalent to SUA (for instance, PAT, port 
address translation), ZyXEL’s Single User Account feature that previous ZyXEL routers 
supported (the SUA Only option in today’s routers). 

• Many to Many Overload: In Many-to-Many Overload mode, the ZyXEL Device maps 

the multiple local IP addresses to shared global IP addresses.

• Many-to-Many No Overload: In Many-to-Many No Overload mode, the ZyXEL Device 

maps each local IP address to a unique global IP address. 

• Server: This type allows you to specify inside servers of different services behind the 

NAT to be accessible to the outside world.