RFC 3256 (rfc3256) - Page 2 of 5
The DOCSIS (Data-Over-Cable Service Interface Specifications) Device Class DHCP (Dynamic Host Configuration Protocol) Relay Agent Information Sub-option
Alternative Format: Original Text Document
RFC 3256 The DOCSIS Device Class DHCP April 2002 is better to trust the operation of the CCCM firmware, than to trust the operation of CCCM software running on the attached computer (e.g., a standard PC). The key words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", and "MAY" in this document are to be interpreted as described in RFC 2119 [4]. 2. DOCSIS Device Class Sub-option The DOCSIS RFI specification [3] specifies the Device Class encoding within the payload of the Device Class Identification Request (DCI- REQ) message. The relay agent MUST pass the Device Class value unchanged to the DHCP server. Possible uses of this field include: o host endpoint information o host hardware capabilities o host software capabilities o host options information DOCSIS defines the Device Class to be a 32-bit field where individual bits represent individual attributes of the CM. Bit #0 is the least significant bit of the field. Bits are set to 1 to select the attributes defined below. bit #0 - CPE Controlled Cable Modem (CCCM) bits #1-31 - Reserved and set to zero The DOCSIS Device Class sub-option is coded as follows: SubOpt Len Device Class +------+------+------+------+------+------+ | 4 | 4 | d1 | d2 | d3 | d4 | +------+------+------+------+------+------+ The DHCP server needs to understand the meaning of this sub-option in order to offer different policy options in its reply to the host. DHCP servers MAY use the device class for IP and other parameter assignment policies for cable modems. Jones & Woundy Standards Track
