Configuring Option Classes
Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2
Windows Server 2003 DHCP includes vendor-defined and user-defined option classes. Use DHCP option classes to configure the parameters necessary for network clients to meet the special requirements of custom applications. Equipment from multiple vendors on a network can also use different option numbers for different functions. The option types used to support vendor-defined classes — the vendor class identifier and the vendor-specific option — are defined in the Internet DHCP options standard reference, RFC 2132.
You can add and configure vendor-defined classes for submanaging DHCP options that are assigned to clients identified by vendor type. You can also add and configure user-defined classes for submanaging DHCP options that are assigned to clients identified by a common need for a similar DHCP option configuration.
After you configure specific user-defined and vendor-defined options classes, you must configure scopes to assign the option classes to clients.
Vendor-Defined Classes
DHCP clients can use vendor-defined classes to identify the client’s vendor type and configuration to the DHCP server when obtaining a lease. For a client to identify its vendor class during the lease process, the client needs to include the vendor class ID option (option code 60) when it requests or selects a lease from a DHCP server.
When vendor options are specified, the server performs the following additional steps to provide a lease to the client:
The server checks to see that the vendor class identified by the client request is a recognized class defined on the server.
If the vendor class is recognized, the server checks to see whether any additional DHCP options are configured for this class in the active scope.
If the vendor class is not recognized, the server ignores the vendor class identified in the client request, and returns options allocated to the default vendor class (includes all DHCP Standard Options).
If the scope contains options configured specifically for use with clients in this vendor-defined class, the server returns those options and uses the vendor-specific option type (option code 43) as part of its acknowledgment message.
In most cases, the default vendor class — DHCP Standard Options — provides a default grouping for any Windows Server 2003 DHCP clients or other DHCP clients that do not specify a vendor class ID. In some cases, you might define additional vendor classes for other DHCP clients, such as printers or some types of UNIX clients. When you add other vendor classes for these purposes, be sure that the vendor class identifier that you use to configure the class at the server matches the identifier used by clients for your third-party vendor.
User-Defined Classes
User-defined classes allow DHCP clients to specify what type of client they are, such as a remote access client or a desktop computer. For Windows Server 2003 clients, you can define specific user class identifiers to relate information about a client’s software configuration, its physical location in a building, or its user preferences. If user-defined option classes are not specified, default settings are assigned.