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Subscriber-ID Suboption for the Dynamic Host Configuration Protocol (DHCP) Relay Agent Option
RFC 3993

Document type: RFC - Proposed Standard (March 2005)
Document stream: IETF
Last updated: 2013-03-02
Other versions: plain text, pdf, html

IETF State: (None)
Consensus: Unknown
Document shepherd: No shepherd assigned

IESG State: RFC 3993 (Proposed Standard)
Responsible AD: Margaret Wasserman
Send notices to: No addresses provided

Network Working Group                                         R. Johnson
Request for Comments: 3993                                T. Palaniappan
Category: Standards Track                                       M. Stapp
                                                     Cisco Systems, Inc.
                                                              March 2005

                    Subscriber-ID Suboption for the
     Dynamic Host Configuration Protocol (DHCP) Relay Agent 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.

Copyright Notice

   Copyright (C) The Internet Society (2005).

Abstract

   This memo defines a new Subscriber-ID suboption for the Dynamic Host
   Configuration Protocol's (DHCP) relay agent information option.  The
   suboption allows a DHCP relay agent to associate a stable
   "Subscriber-ID" with DHCP client messages in a way that is
   independent of the client and of the underlying physical network
   infrastructure.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  2
   2.  Requirements Terminology . . . . . . . . . . . . . . . . . . .  2
   3.  The Subscriber-ID Suboption  . . . . . . . . . . . . . . . . .  2
       3.1.  Suboption Format . . . . . . . . . . . . . . . . . . . .  3
   4.  Relay Agent Behavior . . . . . . . . . . . . . . . . . . . . .  3
   5.  DHCP Server Behavior . . . . . . . . . . . . . . . . . . . . .  4
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . .  4
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  5
   8.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . .  5
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . .  5
       9.1.  Normative References . . . . . . . . . . . . . . . . . .  5
       9.2.  Informative References . . . . . . . . . . . . . . . . .  5
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . .  6
   Full Copyright Statement . . . . . . . . . . . . . . . . . . . . .  7

Johnson, et al.             Standards Track                     [Page 1]
RFC 3993                Subscriber-ID Suboption               March 2005

1.  Introduction

   DHCP (RFC 2131 [2]) provides IP addresses and configuration
   information for IPv4 clients.  It includes a relay agent capability
   in which processes within the network infrastructure receive
   broadcast messages from clients and forward them to DHCP servers as
   unicast messages.  In network environments such as DOCSIS data-over-
   cable and xDSL, it has proven useful for the relay agent to add
   information to the DHCP message before forwarding it, by using the
   relay agent information option (RFC 3046 [3]).

   Servers that recognize the relay agent option echo it back in their
   replies, and some of the information that relays add may be used to
   help an edge device efficiently return replies to clients.  The
   information that relays supply can also be used in the server's
   decision making about the addresses and configuration parameters that
   the client should receive.

   In many service provider environments, it is desirable to associate
   some provider-specific information with clients' DHCP messages.  This
   is often done by using the relay agent information option.  RFC 3046
   defines Remote-ID and Circuit-ID suboptions that are used to carry
   such information.  The values of those suboptions, however, are
   usually based on a network resource such as an IP address of a
   network access device, an ATM Virtual Circuit identifier, or a DOCSIS
   cable-modem identifier.  As a result, the values carried in these
   suboptions are dependent on the physical network configuration.  If a
   client connects to the service provider network through different
   paths, different values are carried in network-dependent suboptions.

2.  Requirements Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [1].

3.  The Subscriber-ID Suboption

   In complex service provider environments, connecting a customer's
   DHCP configuration and administrative information is necessary.  The
   Subscriber-ID suboption carries a value that can be independent of

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