ZyXEL Communications 128MH user manual Advantages of SUA

Prestige 128MH PSTN Router/Hub

The IP address for the SUA can be either fixed or dynamically assigned by the ISP (or other remote node). In addition, you can also configure a server (for example, a Web server) on your local network and make it accessible by outside users.

If you do not set a server IP address, SUA offers the additional benefit of firewall protection. With SUA, even if no server is defined, all incoming inquiries will be filtered out by your Prestige even if you do have a server on your network. This can prevent intruders from probing your system.

Your Prestige accomplishes this address sharing by translating the internal LAN IP addresses to a single address that is globally unique on the Internet. For more information on IP address translation, refer to RFC 1631, The IP Network Address Translator (NAT).

3.5.1 Advantages of SUA

In summary:

•SUA is an ideal cost-effective solution for small offices with less than 20 hosts using a LAN to concurrently access the Internet or other remote TCP/IP network.

•SUA can provide one server address to be accessed by Remote Dial-in Users, thus controlling the incoming packets.

•SUA can provide firewall protection if you do not configure a server IP address. All incoming inquiries will be filtered out by your Prestige protecting the servers on your network.

•UDP and TCP datagrams can be routed. In addition, ICMP echo can also be routed.

Figure 3-4 shows an example of a small office connected to the Internet via a SUA using the Prestige. Note that if you enable the SUA feature, your local IP address MUST be selected from the list of IP addresses for private networks as defined by the IANA.

Chapter 3 Internet Access Application 3-13