Using Multi-Nat; What Is Multi-Nat - ZyXEL Communications P-660R-T1 Support Notes

P-660 series Support Notes
IP address from PNC Monitor or SMT Menu 24.1. If the Internet IP address is a
fixed IP address provided by ISP in SUA mode, then you can always use this IP
address for reaching the VPN server.
In the following example, the IP address '140.113.1.225' is dynamically assigned b y
ISP. You must enter this IP address in the 'VPN Server' dialog box for reaching the
PPTP server. After the VPN link is established, you can start the network protocol
application such as IP, IPX and NetBEUI.

5. Using Multi-NAT

What is Multi-NAT?

NAT (Network Address Translation-NAT RFC 1 631) is the translation of an Internet
Protocol address used within one network to a different IP address known within
another network. One network is designated the inside network and the other is the
outside. Typically, a company maps its local inside network addresses to one or mo re
global out side IP addresses and "unmaps" the global IP addresses on incoming
packets ba ck into local IP addresses. The IP addresses for the NAT can be either fixed
or dynamically assigned by the ISP. In addition, you can designate servers, e.g., a web
server and a telnet server, on your local network and make them accessible to the
outside world. If you do not define any servers, NAT offers the additional benef it of
firewall protection. In such case, all incoming connections to your network will be
filtered out by the P-660, thus preventing intruders from probing your network.
The SUA feature that the P-660 supports previously opera tes by mapping the private
IP addresses to a global IP address. It is only one subset of the NAT. The P-660 with
ZyNOS V3.4 0 support s the most of th e features of the NAT based on RFC 1631, and
41
All contents copyright © 2005 ZyXEL Communications Corporation.