JavaStation Client Software Guide

Vendor-Specific Options

The DHCP specification enables hardware and software vendors to create their own DHCP options. These options are delivered through the use of the Client Class Identifier option and the Vendor-Specific Options option. If a DHCP client identifies itself as being of a certain class of client, and the DHCP server has been configured to serve that class of clients, then the DHCP server can respond with a set of options specific to that client type.

Vendor-Specific Options can be used to deliver the JavaOS checksum, JavaOS property settings, and the JavaOS boot protocol to the JavaStation computer during the boot sequence.

The delivery of Vendor-Specific Options to JavaStation clients works as follows. The DHCP client on the JavaStation (the PROM or the JavaOS software) includes the JavaStation hardware's Client Class Identifier (DHCP Option #60) in every packet sent to the DHCP server. When the DHCP server receives the Client Class Identifier, it will deliver the JavaOS checksum, boot protocol, and/or property settings in the Vendor-Specific Options if it has been configured to do so.

The JavaStation hardware's Client Class Identifier is specified in the PROM. The table below lists the Client Class Identifiers for each JavaStation model.

Table 2-5 JavaStation Client Class Identifiers

JavaStation Model 

Client Class Identifier 

Brick model 


Tower model 


Examine the sample dhcptab file below for examples of setting the JavaOS checksum and JavaOS properties in dhcptab. Note, however, that JavaOS properties can be delivered to the JavaOS software using methods other than the DHCP Vendor-Specific Options. See Chapter 4, JavaOS Properties for more information.