I am attempting to setup Internet Connection Sharing (ICS) on my desktop computer which connects to the internet using an ADSL Speedstream (Optusnet) modem. I have been able to complete this task previously for a dial-up connection, but there does not seem to be a method for the ADSL connection in the Network Connections window. The network between my desktop computer and the other computer works perfectly fine – I just need ICS setup. The computers are running Windows XP.

The most likely reason you are having difficulty setting up ICS on your broadband connection is that the broadband connection operates differently to a dial-up connection. The premise behind ICS is that one computer in the household functions as the internet gateway, through which all other computers connect to the internet. This internet gateway computer has a modem which it uses to access the outside world, and other computers on your internal network send traffic to this gateway computer to access the internet. In this situation, the gateway computer needs to establish the internet connection (if the connection is not active) when a computer on the network needs internet access. On a dial-up connection, it simply dials-up the internet connection. However, a broadband connection is different. On a broadband internet connection the computer connected to the broadband (ADSL) modem does not need to establish the connection, but the modem does this itself. In essence, the modem is a little computer which is your internet gateway. When any computer connected to the ADSL modem needs to access the internet the computer just sends the request to the modem which then establishes the connection. This is why no client or dialling software need be loaded on the computer connected to the modem. Instead, when you initially setup your broadband connection your username, password, and connection details are configured on the modem itself. From my research, this process appears to accurately reflect the setup procedure for Optus ADSL connections: help.optuszoo.com.au/help/dsl/connected/windows/optus_modems/speedstream_4200 .

So, the question remains as to why you cannot use ICS. On the Speedstream 4200 ADSL modems (which I assume is the model you are using, as this appears to be the standard Optus ADSL modem model) there are two methods to connect the model to your computer: Ethernet or USB. When you connect the modem via Ethernet your computer thinks you are just connecting to a local area network (LAN). Technically you are connecting to a LAN, just that it only has two devices – your ADSL modem and your computer. ICS will not allow you to share an internet connection which is provided over a LAN connection, since it deems this unnecessary and complex. It reasons that if you wanted other computers to connect to the internet you would directly connect them onto that LAN rather than using ICS through one computer on the LAN. The same situation holds when you connect the ADSL modem to the computer via USB, as this installs an emulated Ethernet connection on the computer which makes Windows think that it is talking over a normal Ethernet connection but it is actually is transmitting over USB instead.

This is certainly an interesting explanation, but has one major fault. There is only one Ethernet port and one USB port on the ADSL modem and, as far as I am aware, you cannot use both at the same time. As such, you can only connect one computer onto that LAN at one time. Since you cannot enable ICS on that computer, you are unable to share the internet with any other computers. Fortunately, there are two ways around this issue. The first method involves purchasing and installing a network switch to distribute that one internet output to multiple computers. We will use an analogy to demonstrate this concept. Imagine you have one power outlet and need to provide power to two computers. Obviously you will need two power points instead of just one. The easiest method around this issue would be to plug a powerboard into the power outlet which distributes the power available from that one outlet to multiple outlets on the powerboard. A network switch functions exactly the same. You would connect the Ethernet output of your ADSL modem into one of the ports on the Ethernet switch. Then, you would connect all your computers to the remaining ports on the Ethernet switch and voila – you have distributed your internet to multiple computers. You only need a 100 Mbps network switch for this purpose, as your internet connection speed is substantially less than 100 Mbps, and these will cost you around $40.00 (for example: tinyurl.com/5j2j8q). Just make sure the switch you purchase has a feature called “auto-uplink” on the network ports, as this will mean you can use a normal network cable to connect the switch to your modem rather than having to fiddle around with cross-over cables.

The second option is to completely eliminate your Optus-provided ADSL modem and purchase an ADSL modem router. This performs exactly the same function as your current ADSL modem, but also has an inbuilt switch allowing you to (usually) connect up to 4 devices to the modem router. As you may have determined, it is essentially the same setup as proposed in the method outlined above, except instead of having two pieces of hardware (modem and switch) they are built into the one physical device. This is a much neater solution, but is marginally more expensive. For an ADSL modem router with a 4 port switch this will cost around $85.00 (for example: tinyurl.com/6n7way). Alternatively, you may wish to go for a wireless ADSL modem router with a 4 port switch. This is pretty much the same as the previous device, but also includes a wireless radio in case you wish to use a wireless network at your house. This will cost around $110.00 (for example: tinyurl.com/6j2op3).

In any case, using one of the above options is a much easier and neater method of sharing internet when you have a broadband internet connection. Furthermore, it also removes the need for one computer to always be on for the internet service to function.