Connect Everything for Wired Sharing
After you decide whether to use a software or hardware solution for sharing the Internet connection, it’s time to get your hands dirty: All the pieces of the puzzle must be set up and connected.
How to use the software method for wired sharing
When you use the software method to share your Internet connection, one of the computers on your network has both the connection to the Internet and a connection to the LAN. The following figure shows a typical setup for software Internet sharing, whether you’re using a dial-up modem account or a cable/DSL modem for your Internet connection.
Keep in mind, though, that when using a cable/DSL modem for your Internet connection, the computer running the sharing software must have two Ethernet connections.
How to use the hardware method for wired sharing
Not only does using a dedicated piece of hardware free one of the Macs on your network from the onerous job of hosting the shared connection, but it also keeps you from having to have more than one Ethernet connection on a single computer if you’re using a cable/DSL modem for your Internet access.
The following figure shows how you would connect your devices for hardware Internet sharing by using either a cable/DSL router with a built-in Ethernet switch or a cable/DSL router with a stand-alone Ethernet switch.
If you choose to buy a cable/DSL router that has a built-in Ethernet switch, you can simply connect all your computers on the LAN to the built-in switch.
However, if you buy a cable/DSL router that has only a single LAN connection, as with older versions of the AirPort Base Station, you must connect that single LAN connection to an external hub or switch in order to get all the computers on the same network.
Regardless of whether you use the hardware or software method to share your Internet connection, all the computers on your LAN — except the one that’s doing the sharing, if you’re using software sharing — should be configured to obtain its IP address automatically through our old friend, Dynamic Host Configuration Protocol (DHCP).
Although it’s not a requirement that you set up your other devices with DHCP, it’s recommended unless you understand the IP addressing scheme required by your cable/DSL router and you’re willing to set up the addresses manually. You need to follow the instructions that come with the cable/DSL router or software that you purchase for detailed information on how to configure that.