ZyXEL Communications Prestige 28641, User Manual

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46 Configuring for Internet Access
the Internet connection. If the test fails, note the error message that
you receive and take the appropriate troubleshooting steps.
Single User Account
Typically, if there are multiple users on the LAN wanting to concurrently
access the Internet, they will have to subscribe to multiple IP addresses
or a Class C subnetwork from the ISP. In either case, these two
approaches will cost more than a single user account.
The Single User Account (SUA) feature allows customers to have the
same benefits as having a Class C address, but still only pay for one IP
address, thus saving significantly on subscription fees. (Check with your
ISP before you enable this feature).
This feature may also be used to connect to TCP/IP remote nodes
other than Internet Service Providers. For example this feature can be
used to simplify the allocation of IP addresses when connecting branch
offices to the corporate network.
The IP address for the Single User Account can be either fixed or
dynamically assigned by the ISP (or other remote node). In addition,
you can also configure a server, e.g., 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. This is because if no server is defined, all
incoming inquiries will be filtered out by the Prestige even if you do have
a server on your network. This can prevent intruders from probing your
system.
The 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) .