When there is a non-routable, private IP address on the Local WAN interface of a Netopia router, Network Address Translation (NAT) cannot function properly. This is due to the fact that the router needs to translate the private Ethernet IP subnet into a public routed IP address. However, this Netopia Quick Guide will detail how to configure a Netopia router for NAT when the ISP has assigned the router a private Local Wan IP Address.

Please Note: This document is applicable if your router has been assigned a non-routable Local WAN IP Address on a numbered interface with a routable block of IP addresses on the Ethernet interface. As defined in RFC 1918, the following three blocks of the IP address space have been designated for private non-routable networks:

• 10.0.0.0 - 10.255.255.255
• 172.16.0.0 - 172.31.255.255
• 192.168.0.0 - 192.168.255.255

You plan to enable NAT (Network Address Translation) in your router's Internet connection profile and you plan to change the IP subnet on your router's Ethernet interface to one of the above private IP subnets.

Please Note: If your router is currently running Netopia Residential Firmware with a web "GUI" configuration menu, this technote is not applicable to you. Most 3300 Series Netopia Gateways can be upgraded to Enterprise level firmware. Click Here! to purchase the upgrade key.

Firmware References:

• v8.2 R1 (and up) - 3300 Enterprise Series
• v5.3.7   (and up) - 4000 Series 
• v4.8.2   (and up) - R-Series

Before You Start

Telnet into the Netopia router's Main Menu at 192.168.1.1 (if using the default IP setting). If your network has a different IP addressing scheme, modify this accordingly. Click Here! for instructions on using telnet and Hyperterminal (serial connection).

Login with the user name and password. The Superuser login is required to save changes. If you are unsure of this, contact your network administrator.

Don't forget to press the Enter key to save any entries. Hitting the back space, delete or tab without first hitting enter will undo any changes.

The Esc key will take you back towards the main menu screen.

Once you have completed your configuration, you should reboot the Netopia to save and apply your changes.

The Netopia Main Menu Interface

Network Configuration

The following network configuration is the configuration that is referenced in this technote. Please note, the IP addresses used below are examples only. Please substitute your own information for the values used below.

Figure A: Before Implementing NAT

Router Configuration

1. From the Main Menu, go to Quick Menus.
2. Select Network Address Translation.
3. Select Show/Change Public Range.
4. Select the Easy-PAT Range.
5. Change the Public Address from 0.0.0.0 to one of the available routable IP addresses in the subnet allocated to you by your ISP.

   (Note: Considering the above example network configuration, the Public Address would be entered as 200.200.200.201.

6. Select Change NAT Public Range. This will take you back to the Network Address Translation screen.
7. Escape once back to the Quick Menus screen and select IP Setup.
8. Change the Ethernet IP Address and Ethernet Subnet Mask to a private IP address and mask. Any of the designated non-routable IP ranges are acceptable just as long as you don't specify a private IP address within the same private subnet used on your Local WAN interface.

   (Note: For our example, the Ethernet IP Address has been set to 192.168.1.1 with an Ethernet Subnet mask of 255.255.255.0 as illustrated in
   Figure B below. This would make the private IP addresses 192.168.1.2 - 192.168.1.254 available for use on the LAN, whether statically configured or assigned via DHCP.)

9. Next, select Network Address Translation.
10. Select Show/Change Server List.
11. Select Easy-Servers.
12. Select Add Server.
13. Select Service, and select telnet 23 from the pull down menu.
14. Next, change the Server Private IP Address to the Ethernet IP Address you configured in step 8.
15. Then, enter the same Public IP Address that you entered in step 5.
16. Select Add NAT Server at the bottom of the screen. This new entry in the NAT Server List allows telnet access to the router from the WAN interface (in other words, telnet access to the router over the Internet.)
17. Escape twice to return to Quick Menu and select Change Connection Profile.

    Note: If you have an R9100 that DOES NOT use PPPoE to connect to the Internet, escape to the Main Menu instead, and select WAN Configuration -> WAN (Wide Area Network) Setup -> EN (WAN Module 1) Setup. Next, skip to step 19.)

18. Select your Internet Connection Profile, then select IP Profile Parameters.
19. Toggle Address Translation Enabled to Yes with your tab key and hit enter.
20. For NAT Map List, confirm you have Easy-PAT List selected (or a NAT MAP List you have correctly configured on your own).
21. For NAT Server List, confirm you have Easy-Servers selected (or a NAT Server List you have correctly configured on your own).
22. Escape three times back to the Main Menu and select Utilities & Diagnostics.
23. Select Restart System. Now that the configuration is complete, the following network configuration illustrates the solution implemented within this Quick Guide:

Figure B: After Implementing NAT

Conclusion

Now your router is configured for a private IP address on the Ethernet interface, as well as for NAT. If your network was previously configured to communicate with the router via the original routable IP subnet, you will now need to change the configuration of your network to communicate with the router via the new private IP subnet.