ZyXEL Communications P-334WT Support Notes page 17

Some servers providing Internet applications such as some mIRC servers do not allow users to login
using the same IP address. Thus, users on the same network can not login to the same server
simultaneously. In this case it is better to use Many-to-Many No Overload or One-to-One NAT mapping
types, thus each user login to the server using a unique global IP address.
9. What IP/Port mapping does Multi-NAT support?
NAT supports five types of IP/port mapping. They are: One to One, Many to One, Many to Many
Overload, Many to Many No Overload and Server. The details of the mapping between ILA and IGA
are described as below. Here we define the local IP addresses as the Internal Local Addresses (ILA) and
the global IP addresses as the Inside Global Address (IGA),
1. One to One
In One-to-One mode, the Prestige maps one ILA to one IGA.
2. Many to One
In Many-to-One mode, the Prestige maps multiple ILA to one IGA. This is equivalent to
SUA (i.e., PAT, port address translation), ZyXEL's Single User Account feature that
previous ZyNOS routers supported (the SUA only option in today's routers).
3. Many to Many Overload
In Many-to-Many Overload mode, the Prestige maps the multiple ILA to shared IGA.
4. Many to Many No Overload
In Many-to-Many No Overload mode, the Prestige maps each ILA to unique IGA.
5. Server
In Server mode, the Prestige maps multiple inside servers to one global IP address. This
allows us to specify multiple servers of different types behind the NAT for outside access.
Note, if you want to map each server to one unique IGA please use the One-to-One mode.
The following table summarizes these types.
NAT Type
One-to-One
IP Mapping
ILA1<--->IGA1