Managing One Windows XP-based Laptop for the Office and Home
Published: March 4, 2002
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As every IT department knows, employees who get a laptop computer at work inevitably use it for some amount of personal business, even though most corporate policy officially frowns on it.
Sometimes it's hard to tell where official business ends and personal business begins. The good news is that Windows XP Professional eliminates a lot of the calls to help desk when employees are trying to use a laptop in the different environments at home and work.
Before Windows XP, if you had a network at home, moving a laptop from home to work, and vice versa, was a daunting task. You had to reconfigure network settings every time you changed location. You might have needed to create multiple hardware profiles as well, especially if you used a docking station at work.
In Windows XP, the Plug and Play technology quietly handles the hardware configuration changes when you move between home and work. And Windows XP can handle network configuration changes with a new feature called "Alternate Configuration" that makes it simple and easy to keep connected.
Home Networking Scenarios
There are three scenarios you're likely to face when you bring your laptop home from work:
| • | No home network—You either connect directly to the Internet by plugging your network card into the cable or DSL modem, or you use a dial-up connection. |
| • | A home network with a DHCP server—Usually this means you've got an Internet gateway between your cable/DSL modem and the other computers in your house, or you could be running a more complicated network. |
| • | A home network with no DHCP server—Your home computers are all networked but generally you use dial-up to connect to the Internet in this situation. |
The first two situations are easiest to handle. The third scenario requires configuration of the computers on your home network, but after that, Windows XP should make it painless to connect your laptop. First, though, let's talk a little bit about what DHCP is and why you should care.
DHCP
DHCP stands for Dynamic Host Configuration Protocol. Not exactly enlightening, is it? What DHCP means, however, is pretty simple—when you use DHCP, you really don't have to know much of anything about TCP/IP and how to configure it. All the network configuration information is automatically (and dynamically) sent to each machine that asks. When you connect your laptop to a network with a DHCP server, all the necessary information to connect to other machines on the network and on the Internet is automatically handled. In an office network, the DHCP server is usually a special machine whose job it is to keep track of which machine has which address and make sure that none of them conflict. At home, few people are running their own Windows 2000 Server acting as a DHCP server, but if you connect to the Internet with a cable or DSL modem, or through an Internet gateway, you're actually running a DHCP server on the modem or gateway. The modem or gateway handles all the necessary details of sending the configuration information to your laptop when you bring it home and you should be able to just connect to the network and get on with your business, personal or otherwise.
Automatic Private IP Addressing
When there is no DHCP server available on the network, and you don't manually set up the addressing for a specific IP address, Windows XP defaults to use automatic private IP addressing (APIPA, if you really like hopeless acronyms). This automatically assigns an address in the special range between 169.254.0.0 and 169.254.255.255. This automatic IP addressing is supported by Windows 98, Windows Me, Windows 2000 and Windows XP.
Alternate Configuration
Under most circumstances, when you connect to the network at your office, you will automatically be assigned an IP address using DHCP. This is your Primary Configuration. When you come home, however, and you don't have a DHCP server available, Windows XP notices that you are now on a different network and automatically switches to use a different set of TCP/IP settings called the Alternate Configuration. The alternate configuration can use automatic private IP addressing (the default behavior) or you can configure a specific set of IP addresses. If you set up all the computers on your home network to use automatic private IP addressing, they all see each other without problems and when your laptop comes home, it will see and be seen as well.
To choose automatic private IP addressing for your alternate configuration
1. | Open the properties dialog for your network card. Click Control Panel, click Switch to Classic View, and then click Network Connections. |
2. | Right-click on the network card icon, and click Properties. This will open up the properties dialog as shown in Figure 1 below.  Figure 1. |
3. | Select Internet Protocol (TCP/IP), and then click on Properties to bring up the dialog shown in Figure 2 below.  Figure 2. |
4. | Click on the Alternate Configuration tab to bring up the dialog shown in Figure 3 below.  Figure 3. Note If your network card is not set to Obtain an IP address automatically, you will not see a tab for Alternate Configuration. You must be using automatic addressing on the primary configuration to have an alternate. |
5. | If you are using automatic private IP addressing for the alternate configuration, just leave that box checked. If your home network is using some other set of IP addresses, you can configure the TCP/IP properties here. They will apply only when you're laptop is not on your office network. |
After you have Alternate Configuration set up, your laptop will switch between configurations whether you're at home or at work, and you won't have to think about it.
In my next column, I'll be talking about optimizing your laptop for power conservation and performance. In Windows XP, you can fine tune your settings to suit the way you work.
If you use Windows XP Professional at work, and you have a topic you'd like to see me cover in one of my columns, feel free to write me at: Charlie@mvps.org. Please understand that I cannot answer individual e-mail messages. But I will be happy to consider your topic request for a future column.
