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Networking Two PCs Via a Crossover Cable

This week we'll show you how to connect two PCs together with just a crossover cable. We also answer that age old question, "What is the difference between a Hub and a Switch?"

By Ron Pacchiano

Q. I've heard that it is possible to connect two PCs together using a crossover cable, but I haven't been able to do so. I'd like these machines to be able to share my dial-up Internet connection, along with my inkjet printer and some data. The LAN connection appears to be enabled and connected, but they can't seem to communicate with each other. I've tried a number of different things to get around it, but nothing seems to work. Could you please provide me with some simple instructions for doing this?

A. Connecting two PCs directly to each other is a relatively simple and straightforward process. For starters, both PCs need to have properly installed Ethernet adapters. This means that the device driver for the NIC is loaded and Device Manager reports it as enabled and working. Next you'll need to configure each adapter with a static IP address and a common Subnet. For our example we'll assign the first PC an IP address of 192.168.0.1 and the second PC an address of 192.168.0.2. Both machines should be given the Subnet 255.255.255.0.

Now you want to make sure that both machines have been configured as members of the same workgroup. Any name will work for the workgroup name as long as it doesn't exceed 15 characters (ex.WORKGROUP). The last thing you'll need is a crossover cable. A crossover cable is a specific cable, not to be confused with a patch cable, that's readily available at most computer stores; using a regular patch cable instead of a crossover cable could be the source of connectivity problems.

The Crossover cable will be connected to the Ethernet port of each PC. All that's left to do now is reboot the system. Upon reboot, go to a DOS prompt and try to Ping the other PC. To do this just type PING and the IP address of the system you're trying to reach (ex. C:\>PING 192.168.0.2). You should get 5 replies.

If for some reason your Ping returns a timeout message, then you might have another problem. The most common issue has to do with Windows XP and the Internet Connection Firewall (ICF). The Windows XP Network Setup Wizard will sometimes enable ICF on your Ethernet adapter. ICF is designed to protect you from threats outside of your network by blocking unauthorized traffic from reaching your PC. It is supposed to be used only on the interface that directly connects to your Internet connection. However, if ICF is enacted on an interface that is being used to connect to another PC, it will block all the transmissions being sent to it. It will not even respond to pings. ICF must be disabled in order for the connection to work.

To disable ICF simply right-click on "My Network Places" and select Properties. Right-click on your LAN connection and again select Properties. Go to the Advanced tab and uncheck the box that reads "Protect my computer and network by limiting or preventing access to this computer from the Internet." Click OK. Now try to ping the other PC again. It should work fine.

Now that your PCs can see each other, they need to be configured to share your Internet connection. This is done using Windows XP's Internet Connection Sharing or (ICS). Configuring ICS is a relatively simple process to set up, and detailed instructions for this can be found at http://support.microsoft.com/default.aspx?scid=kb;EN-US;306126, which explains how to configure both the host and client sides of ICS.

The only thing left to do now is enable file and print sharing. The procedure for sharing a drive, folder or printer is pretty much the same. To share a folder simply open Windows Explorer and locate the folder you want to share. Right-click it and select Sharing and Security. Go to the Sharing tab and select the option "Share this folder on the network." If you wanted to share a drive, you would check the box that reads "you understand the risk but still want to share the root of the drive." After you say OK, a small hand will appear under the drive or folder you selected. This indicates that sharing has been enabled and the folder will now be accessible from the other PC.

Sharing a printer is almost identical to sharing a folder. Just right-click on the printer you want to share and select Properties. Go to the sharing tab and select "Share this Printer." Give the printer a shared name and press OK. The hand will appear and the printer will now be shared.

This completes the configuration of your network. Good Luck!

Q. I have a couple of PCs at home and would like to set up a simple home network. I don't currently have a cable modem for Internet access, but I plan to have one in the near future. I was told by a friend of mine that in order to connect my PCs together I'd need a hub and a few Ethernet network cards. So I ordered them the other day. Today I had someone tell me that I should have ordered a Switch instead. When I asked him why I needed a switch and not a hub, he couldn't explain the differences to me, but he insisted that the switch was better. So my question is did I make a mistake ordering the hub and what is the difference between the two?

A. The short answer is no, you did not make a mistake ordering the Hub. However, your friend is also right when he says that a Switch is better.

A Hub and Switch have very similar functions. Each serves as a central connection for all of your network equipment and handles a data type known as "Frames." Frames carry your data. When a Frame is received, it is amplified and then transmitted on to the port of the destination PC. The big difference between these two devices is in the method in which Frames are being delivered.

In a Hub, a Frame is passed along or broadcast to each of its ports. It doesn't matter that the Frame is only destined for one port. The Hub has no way of distinguishing which port a Frame should be sent to. Passing it along to every port ensures that it will reach its intended destination. This places a lot of traffic on the network and can lead to poor network response times.

Additionally, a 10/100Mbps Hub must share its bandwidth with each and every one of its ports. So when only one PC is broadcasting, it will have access to the maximum available bandwidth. If, however, multiple PCs are broadcasting, then that bandwidth will be divided between all of those systems, degrading performance.

A Switch, on the other hand, keeps a record of the MAC addresses of all the devices connected to it. With this information, a Switch can identify which system is sitting on which port. So when a Frame is received, it knows exactly which port to send it to, significantly increasing network response times. And unlike a Hub, a 10/100Mbps Switch will allocate a full 10/100Mbps to each of its ports. So regardless of the number of PCs transmitting, users will always have access to the maximum amount of bandwidth. These are a couple of the reasons why a Switch is considered to be a much better choice then a hub.

One last piece of advice; if you are planning to add a cable modem to your network in the not to distance future you might want to consider trading in your hub for a Cable/DSL Router. Many routers today have built-in switches ranging from 4 to 8 ports. This would solve your immediate need for a Switch and make upgrading to broadband later as easy as plugging in a cable. Good, low cost routers are available from D-Link, Netgear and Linksys just to name a few.

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