Implementing User Classes

User classes allow you to apply a particular configuration of DHCP options to any subset of DHCP clients you define. To implement a user class, you first define the class at the DHCP server by assigning an ID and set of options for the class. Then you assign selected client computers to the class by using the Ipconfig /setclassid command. When these clients subsequently communicate with DHCP servers, they announce their class ID and inherit the options of that class.

A custom user class is helpful when you need to assign distinct options to distinct sets of client computers. For example, your network might require that clients with the security clearance to bypass the company firewall be assigned a unique default gateway. In this example, you could configure options to distribute the unique default gateway to the security-exempt class.

To create a custom or new user class, right-click the DHCP server icon in the DHCP console and select Define User Classes.

You then need to set an ID string for the class. You designate this class ID string when you first create the class in the DHCP console. After defining a new class and specifying an ID string for that class, you can then set desired options for that class.

Finally, for the desired computers to inherit the options of the new class, you need to set the class ID of appropriate client computers to match the ID you have defined for that class at the DHCP server. You can achieve this task by executing the Ipconfig /setclassid command at a command prompt at each client computer. The user class option permits only one class ID to be used for identifying clients. In other words, each client computer can be identified as a member of only a single user class at the DHCP server.

To create a new user or vendor class, complete the following steps:

1. Open the DHCP console.
2. In the console tree, select the applicable DHCP server.
3. JFrom the Action menu, select one of the following:
   • To create a new user class, select Define User Classes.
   • To create a new vendor class, select Define Vendor Classes.
4. JClick Add.
   The New Class dialog box opens.
5. JIn the Display Name text box, provide a friendly name for the class. Optionally, fill in the Description text box.
6. JIn the ID text box, set the same binary or ASCII string that matches the DHCP class ID string that is either implemented or set at member clients.
7. Click OK and then Close to return to the DHCP console.

To set DHCP class ID information at a client computer, complete the following steps:

1. JAt a DHCP-enabled client computer running Windows 2000, Microsoft Windows XP, or Windows Server 2003, open a command prompt.
2. JUse the Ipconfig /setclassid command to set the DHCP class ID the client uses when obtaining its lease from the DHCP server.
   You can use the Ipconfig /setclassid command as demonstrated in the following example command, which sets an ASCII string (MyNewClassId) as the DHCP class ID string for the local area network (LAN) connection in use at the client computer:

   C:\>ipconfig /setclassid "Local Area Connection" MyNewClassId
   
   Windows IP Configuration
   
   Successfully set the class id for adapter Local Area Connection.
   

Note You can use the Ipconfig /showclassid <adapter number> command to display all the DHCP class IDs allowed by the DHCP server for any network adapter installed on your computer.