RFC 3256 (rfc3256) - Page 1 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
Network Working Group D. Jones
Request for Comments: 3256 YAS Corporation
Category: Standards Track R. Woundy
AT&T Broadband
April 2002
The DOCSIS (Data-Over-Cable Service Interface Specifications) Device
Class DHCP (Dynamic Host Configuration Protocol) Relay Agent
Information Sub-option
Status of this Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Abstract
This document proposes a new sub-option to the DHCP (Dynamic Host
Configuration Protocol) Relay Agent Information Option. This new
sub-option is for use with DOCSIS (Data-Over-Cable Service Interface
Specifications) cable modems and describes a "device class" to which
the cable modem belongs. The cable modem signals its device class
information to the Relay Agent using DOCSIS signaling, and the Relay
Agent forwards the device class information to the DHCP Server which
can then make a policy decision based on it.
1. Introduction
The "Relay Agent Information" Option is described in [1] and includes
several Relay Agent Information sub-options. This RFC proposes an
additional sub-option for use with DOCSIS cable modems. This sub-
option is added by DHCP relay agents which terminate cable modems.
The sub-option encodes an identifier of the device class to which the
cable modem belongs. It is intended for use by DHCP servers to make
policy decisions based on the device class of the host.
The motivation for using a Relay Agent Information sub-option, rather
than a new or existing DHCP option, is the introduction of CPE
Controlled Cable Modems (CCCMs) [2]. In an implementation of a CCCM,
the modem firmware controls DOCSIS signaling, but the attached
computer (CPE) manages other protocol activities -- particularly DHCP
client message handling. The assumption of this document is that it
Jones & Woundy Standards Track