The DHCPv4 Relay Agent Identifier Sub-Option
RFC 6925

Document Type RFC - Proposed Standard (April 2013; No errata)
Last updated 2013-04-29
Stream IETF
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IESG IESG state RFC 6925 (Proposed Standard)
Telechat date
Responsible AD Ralph Droms
IESG note Ted Lemon (ted.lemon@nominum.com) is the document shepherd.
Send notices to dhc-chairs@ietf.org, draft-ietf-dhc-relay-id-suboption@ietf.org
Internet Engineering Task Force (IETF)                          B. Joshi
Request for Comments: 6925                                    R. Desetti
Category: Standards Track                                   Infosys Ltd.
ISSN: 2070-1721                                                 M. Stapp
                                                     Cisco Systems, Inc.
                                                              April 2013

              The DHCPv4 Relay Agent Identifier Sub-Option

Abstract

   This document defines a new Relay Agent Identifier sub-option for the
   Dynamic Host Configuration Protocol (DHCP) Relay Agent Information
   option.  The sub-option carries a value that uniquely identifies the
   relay agent device within the administrative domain.  The value is
   normally administratively configured in the relay agent.  The sub-
   option allows a DHCP relay agent to include the identifier in the
   DHCP messages it sends.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6925.

Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Joshi, et al.                Standards Track                    [Page 1]
RFC 6925              The Relay Agent ID Sub-Option           April 2013

Table of Contents

   1. Introduction ....................................................2
   2. Terminology .....................................................2
   3. Example Use Cases ...............................................3
      3.1. Bulk Leasequery ............................................3
      3.2. Industrial Ethernet ........................................3
   4. Sub-Option Format ...............................................4
   5. Identifier Stability ............................................4
      5.1. Identifier Uniqueness ......................................5
   6. Security Considerations .........................................6
      6.1. Forged Relay ID Attacks ....................................6
      6.2. Factory-Floor Scenario .....................................6
   7. IANA Considerations .............................................7
   8. Acknowledgments .................................................7
   9. References ......................................................7
      9.1. Normative References .......................................7
      9.2. Informative References .....................................8

1.  Introduction

   The Dynamic Host Configuration Protocol for IPv4 (DHCPv4) [RFC2131]
   provides IP addresses and configuration information for IPv4 clients.
   It includes a relay agent capability, in which network elements
   receive broadcast messages from clients and forward them to DHCP
   servers as unicast messages.  In many network environments, relay
   agents add information to the DHCP messages before forwarding them,
   using the Relay Agent Information option [RFC3046].  Servers that
   recognize the Relay Agent Information option echo it back in their
   replies.

   This specification introduces a Relay Agent Identifier (Relay-ID)
   sub-option for the Relay Agent Information option.  The Relay-ID sub-
   option carries a sequence of octets that is intended to uniquely
   identify the relay agent within the administrative domain.  In this
   document, an administrative domain consists of all DHCP servers and
   relay agents that communicate with each other.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
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