This article describes setting up Macintosh computers, both with and without AirPort capability, to utilize an AirPort Base Station through cable or digital subscriber line (DSL) modem, or a dial-up (PPP) connection.

There are a couple of ways you can connect a Macintosh with Ethernet, such as a Power Macintosh G3, to the Base Station to obtain Internet services via cable modem, DSL, or PPP.

If you are only sharing the Internet connection with wireless clients, you can connect the Base Station directly to your cable or DSL modem. If you are sharing the Internet connection with both wireless and Ethernet clients, an Ethernet hub will be required to connect non-AirPort capable computers to the Base Station.

Cable or DSL Connection Using DHCP

This setup assumes that you have successfully connected to the Base Station and the Internet from an AirPort capable computer such as an iBook. To add the Power Macintosh G3, set its TCP/IP control panel to use Network Address Translation (NAT) provided by the Base Station.

No changes are necessary to the Base Station when the ISP is using DHCP. By properly setting up the TCP/IP control panel, the Base Station can serve as a DHCP/NAT server to wired or wireless client computers. In this case, you will only make use of NAT services.

Warning: When connecting a wired client to your Base Station to share cable Internet service, it is strongly recommended that you NOT allow the Base Station to provide IP addresses over Ethernet.

Connect your cable or DSL modem to the Ethernet hub. Then connect any computers to the hub that will use NAT services from the Base Station. To setup your wired computers, you need only:

• set the TCP/IP control panel to an IP address outside the range that it is being served wirelessly by the Base Station
• not set your wired computers to DHCP

Figure 1: TCP/IP Control Panel Setup for Cable Modem

You could set up the Base Station so that it provides IP addresses on Ethernet, but this could cause trouble. Both your service provider's DHCP server and the Base Station would be attempting to provide IP addresses to any computers connected by Ethernet. This would cause conflicts and result in unreliable connections for both the wired and wireless computers. This could potentially disable all Internet traffic through your cable or DSL modem until the modem is reset.

Using a Static IP Address via Cable or DSL

If the cable ISP provided a static IP address for your connection, it is still appropriate to use the same setup as described above. While the AirPort Admin Utility software allows you to set up the Base Station to provide DCHP addresses over Ethernet, your Base Station could respond to DHCP requests from the Internet and create unwanted Internet traffic. This is not desirable to you or your ISP.

Note: This is unlikely to be an issue with DSL.

Dial-up PPP Connection

The setup described for cable or DSL modems should work with dial-up connections. No changes need to be made to the Base Station. Use the TCP/IP control panel on your wired computer to define the connection. In the TCP/IP control panel on the computer using Ethernet, enter an IP address of 10.0.1.201. Additional computers would be set to the next number 10.0.1.202, an so forth, up to 10.0.1.254. Enter the subnet address of 255.255.255.0 and a router address of 10.0.1.1. The DNS IP addresses and the domain names should be the same as those used for your ISP. The TCP/IP control panel should appear as in Figure 2:

Figure 2: TCP/IP Control Panel Setup forPPP Connection

Note: The warning about providing IP addresses over Ethernet from the Base Station does not apply to PPP connections. If need be, you can set up the Base Station to provide IP addresses over the Ethernet for your wired client computers.

In the TCP/IP control panel for the wired computers, set them to "Connect via Ethernet" and "Configure Using DHCP Server."

Note: Wireless Internet access requires AirPort Card, AirPort Base Station, and Internet Access (fees may apply). Some ISPs are not currently compatible with AirPort, including America Online. Range may vary with site conditions.