Network Working Group D. Jones
Request for Comments: 3256 YAS Corporation
Category: Standards Track R. Woundy
AT&T Broadband
April 2002
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
DOCSIS（有线数据服务接口规范）设备类DHCP（动态主机配置协议）中继代理信息子选项
Status of this Memo
本备忘录的状况
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.
本文件规定了互联网社区的互联网标准跟踪协议，并要求进行讨论和提出改进建议。有关本协议的标准化状态和状态，请参考当前版本的“互联网官方协议标准”（STD 1）。本备忘录的分发不受限制。
Abstract
摘要
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.
本文档为DHCP（动态主机配置协议）中继代理信息选项提出了一个新的子选项。此新的子选项用于DOCSIS（电缆数据服务接口规范）电缆调制解调器，并描述电缆调制解调器所属的“设备类”。电缆调制解调器使用DOCSIS信令将其设备类别信息发送给中继代理，中继代理将设备类别信息转发给DHCP服务器，然后DHCP服务器可以基于此做出策略决策。
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.
[1]中描述了“中继代理信息”选项，包括几个中继代理信息子选项。本RFC提出了一个额外的子选项，用于DOCSIS电缆调制解调器。此子选项由终止电缆调制解调器的DHCP中继代理添加。子选项对电缆调制解调器所属的设备类别的标识符进行编码。它用于DHCP服务器根据主机的设备类别做出策略决策。
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
使用中继代理信息子选项而不是新的或现有的DHCP选项的动机是引入CPE控制的电缆调制解调器（CCCMs）[2]。在CCCM的实现中，调制解调器固件控制DOCSIS信令，但连接的计算机（CPE）管理其他协议活动，特别是DHCP客户端消息处理。本文件的假设是：
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).
最好信任CCCM固件的操作，而不是信任连接的计算机（例如，标准PC）上运行的CCCM软件的操作。
The key words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", and "MAY" in this document are to be interpreted as described in RFC 2119 [4].
本文件中的关键词“必须”、“不得”、“应该”、“不应该”和“可能”应按照RFC 2119[4]中的描述进行解释。
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:
DOCSIS RFI规范[3]规定了设备类标识请求（DCI-REQ）消息有效载荷内的设备类编码。中继代理必须将设备类值不变地传递给DHCP服务器。该字段的可能用途包括：
o host endpoint information
o 主机端点信息
o host hardware capabilities
o 主机硬件功能
o host software capabilities
o 主机软件功能
o host options information
o 主机选项信息
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.
DOCSIS将设备类定义为32位字段，其中各个位表示CM的各个属性。位#0是字段的最低有效位。位设置为1以选择下面定义的属性。
bit #0 - CPE Controlled Cable Modem (CCCM)
比特#0-CPE控制的电缆调制解调器（CCCM）
bits #1-31 - Reserved and set to zero
位#1-31-保留并设置为零
The DOCSIS Device Class sub-option is coded as follows:
DOCSIS设备类子选项编码如下：
SubOpt Len Device Class
+------+------+------+------+------+------+
| 4 | 4 | d1 | d2 | d3 | d4 |
+------+------+------+------+------+------+
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.
DHCP服务器需要理解此子选项的含义，以便在其对主机的答复中提供不同的策略选项。DHCP服务器可以将设备类用于IP，并将其他参数分配策略用于电缆调制解调器。
Operation of the DHCP Relay Agent Information Option relies on an implied trusted relationship between the DHCP relay agent and the DHCP server. The discussion of security considerations for the DHCP relay agent information option [1] apply to this sub-option as well.
DHCP中继代理信息选项的操作依赖于DHCP中继代理和DHCP服务器之间的隐含信任关系。DHCP中继代理信息选项[1]的安全注意事项讨论也适用于此子选项。
Operation of the DOCSIS Device Class sub-option relies on an implied trusted relationship between the DHCP client (i.e., the cable modem) and the DHCP relay agent, through DOCSIS signaling. According to DOCSIS specifications [2], the cable modem firmware always controls DOCSIS signaling, but cannot control DHCP client message handling (e.g., CCCMs). This document assumes that the cable modem firmware is trustworthy for DOCSIS signaling information.
DOCSIS设备类子选项的操作依赖于DHCP客户端（即电缆调制解调器）和DHCP中继代理之间通过DOCSIS信令的隐含信任关系。根据DOCSIS规范[2]，电缆调制解调器固件始终控制DOCSIS信令，但不能控制DHCP客户端消息处理（例如CCCMs）。本文档假设电缆调制解调器固件对于DOCSIS信令信息是可靠的。
This document introduces a new identifier, the DOCSIS Device Class sub-option, that is provided by the relay agent device and is assumed to be trusted. Cryptographic or other techniques to authenticate the device class are beyond the scope of this document.
本文档引入了一个新的标识符DOCSIS设备类子选项，该标识符由中继代理设备提供，并假定为可信的。用于验证设备类的加密或其他技术超出了本文档的范围。
IANA has assigned a value of 4 from the DHCP Relay Agent Sub-options space [RFC 3046] for the DOCSIS Device Class sub-option defined in section 2.
IANA已从DHCP中继代理子选项空间[RFC 3046]为第2节中定义的DOCSIS设备类子选项分配了值4。
[1] Patrick, M., "DHCP Relay Agent Information Option", RFC 3046, January 2001.
[1] Patrick，M.，“DHCP中继代理信息选项”，RFC 3046，2001年1月。
[2] "Data-Over-Cable Service Interface Specifications: Cable Modem to Customer Premise Equipment Interface Specification SP-CMCI-I07-020301", DOCSIS, March 2002, http://www.cablemodem.com.
[2] “电缆数据服务接口规范：电缆调制解调器至客户场所设备接口规范SP-CMCI-I07-020301”，DOCSIS，2002年3月，http://www.cablemodem.com.
[3] "Data-Over-Cable Service Interface Specifications: Cable Modem Radio Frequency Interface Specification SP-RFIv1.1-I08-020301", DOCSIS, March 2002, http://www.cablemodem.com.
[3] “电缆数据服务接口规范：电缆调制解调器射频接口规范SP-RFIv1.1-I08-020301”，DOCSIS，2002年3月，http://www.cablemodem.com.
[4] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[4] Bradner，S.，“RFC中用于表示需求水平的关键词”，BCP 14，RFC 2119，1997年3月。
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Acknowledgement
确认
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