Troubleshooting Q&A - January 15, 2004
Networking Multiple Computers Without a Hub
In some cases, it doesn't make sense or is simply not feasible to use a hub when networking multiple computers. This week's Q&A steps through the process of setting up a network and sharing internet access without using a hub or switch.
By Ron Pacchiano
Q. I’m an English teacher at the local high school and have managed to scrounge up a few extra computers for use in my classroom. All of the computers are running Windows XP, and one computer in the classroom is equipped with Internet access, while the others are not. I would like to be able to share this Internet connection between all three PCs. I’ve tried getting the I.T. staff to bring me a hub, but they don’t have one available.
I brought in a stack of old Ethernet adapters that I had at home and thought that I might be able to use them to connect all of the PCs together and then use Microsoft Internet Connection Sharing (ICS) to give them access to the Internet. When setting up my home network I remembered seeing this option displayed in the Network Setup Wizard, so I thought I would be able to implement it here.
Yet for some reason, no matter what I try, I just can’t seem to get it to work. I've spent literally hours trying to resolve this issue. Any suggestions you have that might resolve this issue would be greatly and sincerely appreciated. Thank you!
A. In the past, whenever I’ve received questions like this my first response is to suggest simply investing in a low cost hub. And when I say low cost, I mean somewhere in the neighborhood of $25. Otherwise, in order for you to do what you're looking to achieve you would need to have one (1) network adapter in the first PC, two (2) network adapters in the second PC, and two (2) network adapters in the Host PC. The PCs equipped with two network adapters would then need to be bridged (or multi-homed) to pass data between them. To say that this could be problematic would be an understatement, and in most situations I would not recommend it. For the $25 price of the hub, it simply isn’t worth the aggravation.
Since you are a teacher, I understand your resistance in shelling out money on equipment that by all rights the school administration should provide. And because your IT staff doesn’t have a hub available but should have plenty of NICs (network adapter cards) and Ethernet cables in reserve (if you need more than you already have), I’m going to forgo my usual response and instruct you on what steps you need to take in order to get these PCs up and running. Since you’re running Windows XP on those systems, it really isn’t that complicated. However, with any other version of Windows I would seriously consider investing in a hub.
To begin, you’re going to need some parts from your stash or from I.T. The list of parts is as follows:
5 Network Adapters; 1 for PC 1, 2 for PC 2, and 2 for the Host PC
The first thing you need to do is install all of the network adapters into the PCs. With any luck, Windows XP will be able to install the drivers for these adapters automatically. If not, you’ll need to download the drivers from the vendor’s website and refer to the documentation for the proper installation procedure. Use the Device Manager to verify that the drivers have been installed and are working.
Once the functionality of your network cards has been verified, we can begin the next step of the installation — bridging the network adapters of PC 2 (better known as the one in the middle). This is done by right-clicking on “My Network Places” and selecting Properties. Now hold down the “Control” key and click on both network adapters. This will highlight both of them.
Right-click on the highlighted area and select “Bridge Connections”. Windows will now begin bridging the connections. Once finished, you’ll see a new adapter listed under Network Connections labeled “Network Bridge”. With the bridge created, we can now install ICS on the Host PC (the one with the Internet connection).
At this point there should be two network adapters in the Host PC. One of these adapters will be connected to your school’s network via the straight-through cable. Go back into Network Connection by right-clicking on “My Network Places” and selecting Properties. Now right-click on the network adapter connected to the schools network and select Properties. Go to the Advanced tab, and under the section “Internet Connection Sharing,” check the box labeled “Allow other network users to connect through this computers Internet connection” and press “OK.” ICS is now enabled.
At this point I recommend shutting down all three computers. Once they’re off, connect one of the crossover cables to the free network adapter on the Host PC, and connect the other end of the cable to one of the network adapters on PC 2. Connect the other crossover cable to the remaining network adapter on PC 2 and insert it into the Network adapter on PC 1. All of the PCs should now be linked together.
With that completed, the only thing left to do is reboot the PCs. Boot the Host computer first. Once booting has completed, verify that this system still has working Internet conductivity. Once verified, you can go ahead and boot up PCs 1 and 2. If everything went according to plan, all of these systems should now have access to the Internet.
If not, then you have other issues to contend with. Any number of variables could prevent this network configuration from functioning correctly. ICS is typically only used to connect a group of PCs to a cable modem, DSL line, or dial-up modem. The most difficult thing about this configuration is simply the fact that you’re trying to share the Internet connection of an existing network. Because of this, the biggest obstacle you’re likely to encounter will have to do with IP addresses.
The reason for this is that most internal networks base their IP address on the non-routable addresses of 192.168.x.x. By default, ICS will manage DHCP assignments based on this address scheme. So if your school’s network is also using 192 addresses, ICS is not going to be able to initialize. Regrettably, to the best of my knowledge, ICS’s DHCP scope cannot be altered. So in this situation you’ll have no choice but to invest in a hub. I hope this helps you. Good luck!
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