Have a wireless adapter that's finding it difficult to obtain an IP address from your wireless router's DHCP server? This week we'll cover some of the more common issues that can prevent your wireless networking gear from talking to each other.

By Ron Pacchiano

Q. I have a wireless USB network adapter that is configured to automatically receive an IP address from the wireless router's DHCP server, yet for some reason it doesn't appear to be working. When I run IPCONFIG it reports that my system is using an IP address that begins with a 169. Yet my router's DHCP address pool is set to assign addresses that start with a 192. So I don't know where it is getting the 169 address from. Could I be connecting to someone else's wireless router? I've tried a number of things to fix it, but I'm at a loss. What do I need to do to resolve this problem?

A. I doubt very much that you're linking to another router. An IP address that begins with a 169 typically means that the NIC is not communicating with the DHCP server. This would indicate to me that the problem is more likely related to the way you've configured your wireless network. Don't be discouraged, though; wireless networks can sometimes be very complicated to setup, particularly if you're dealing with encryption and products from different vendors. Any number of variables can keep your workstations from talking with each other. Let's go over some of the more common ones.

For starters, verify that your router and your workstation are using the same SSID descriptions. SSID is short for Service Set Identifier. This is a 32-character unique identifier attached to the header of packets sent over a WLAN and acts as a password when a mobile device tries to connect to the wireless network. The SSID also differentiates one WLAN from another, so all access points and all devices attempting to connect to a specific WLAN must use the same SSID. A workstation will not be permitted to connect to the network unless it can provide this unique identifier. This is similar to the function of your network's Workgroup or Domain name.

When you're experiencing conductivity problems, it is always best to keep things simple. So next you are going to want to disable any WEP encryption you might have configured. Encryption can be one of the most convoluted components of a wireless network, and its implementation can vary from vendor to vendor. For example, your router might be set for either 64 or 128-bit encryption, while another manufacturer's network adapter might use only 40 or 256-bit encryption, which will of course prevent the two from making a secure connection.

Successful implementation of encryption also includes the use of a shared key. A HEX key is most common, but other formats are also used. This key identifies the workstation to the router as a trusted member of this network. Different manufactures can implement this key technology in ways that might prevent them from working correctly with another vendor's products. So attention to detail is going to be the key to a successful installation.

Next make sure the router and the NIC are configured to use the same communications channel. There are normally 11 of them, and the default channel can also vary from vendor to vendor. You might also want to confirm that the router has DHCP services enabled and an address pool configured. If not, the NIC won't be able to pick up an IP address. I have run across a few access points that offer DHCP services but do not assign all of the needed IP information to the NIC. For example, I was reviewing one product that would assign a workstation an IP address, subnet mask, and gateway, but would not provide it with any DNS information. As a result, I was able to connect to the network, but could not browse the web. The point is, don't assume anything. Verify for yourself that all of the required settings are being received by the workstation.

Finally, you might want to keep the system you're trying to configure in the same room as the router, at least during the initial configuration, in order to minimize potential interference from concrete walls or steel beams.

Once you get the workstation and the wireless NIC talking to each other, verify that your workstation is part of the same domain or workgroup as the rest of the network systems. If not, you won't be able to see or access any other systems on the network. This should be enough information to get you started. Just cross your t's and dot your i's, and everything should workout fine. Good Luck!

Q. I'm currently using the Ethernet connection on my desktop to link to my laptop computer. I'd like to add a broadband connection to my systems, but I'm not sure how I would go about connecting them, as I have no more Ethernet ports available to plug in the Internet cable. How can I give both of these systems access to the internet?

A. This is a relatively straightforward question. The easiest thing to do would be to purchase a low cost router such as the FriendlyNET FR1004 4-Port Router. This router sells for about $65 and not only allows you to share an Internet connection with multiple PCs, but also provides your network with NAT firewall security to help protect your home or office network from would-be hackers. A full review of the FriendlyNET can be found athttp://www.practicallynetworked.com/review_prnt.asp?pid=516. I highly recommend using a firewall with any type of broadband technology. Using this router, you could have both machines surfing the web in no more than 5 minutes.

Other options available would be to create a multi-homed system by adding a second NIC card to your desktop. This would allow you to use one connection for Internet WAN traffic and the other for local LAN traffic. This is a much more complicated procedure, however, and could prove to be VERY problematic. The Microsoft Knowledge Base can provide you with information on how to do this, as it is just too complicated to get into detail in this column. My advice: save yourself the headache and just invest in the router.

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