IANA Allocation Guidelines for the Address Resolution Protocol (ARP)
RFC 5494

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Network Working Group                                           J. Arkko
Request for Comments: 5494                                      Ericsson
Updates: 826, 951, 1044, 1329, 2131,                        C. Pignataro
         2132, 2176, 2225, 2834, 2835,                     Cisco Systems
         3315, 4338, 4361, 4701                               April 2009
Category: Standards Track

  IANA Allocation Guidelines for the Address Resolution Protocol (ARP)

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) 2009 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 in effect on the date of
   publication of this document (http://trustee.ietf.org/license-info).
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.

Abstract

   This document specifies the IANA guidelines for allocating new values
   in the Address Resolution Protocol (ARP).  This document also
   reserves some numbers for experimentation purposes.  The changes also
   affect other protocols that employ values from the ARP name spaces.

Arkko & Pignataro           Standards Track                     [Page 1]
RFC 5494                     ARP IANA Rules                   April 2009

1.  Introduction

   This document specifies the IANA guidelines [RFC5226] for allocating
   new values for various fields in the Address Resolution Protocol
   (ARP) [RFC0826].  The change is also applicable to extensions of ARP
   that use the same message format, such as [RFC0903], [RFC1931], and
   [RFC2390].

   The change also affects other protocols that employ values from the
   ARP name spaces.  For instance, the ARP hardware address type
   (ar$hrd) number space is also used in the "htype" (hardware address
   type) fields in the Bootstrap Protocol (BOOTP) [RFC0951] and Dynamic
   Host Configuration Protocol (DHCP) [RFC2131], as well as in the
   "hardware type" field in the DHCP Unique Identifiers in DHCPv6
   [RFC3315].  These protocols are therefore affected by the update in
   the IANA rules.  Other affected specifications include the
   specialized address resolution mechanisms in:

   o  HYPERchannel [RFC1044]

   o  DHCP options [RFC2132] [RFC4361]

   o  ATM (Asynchronous Transfer Mode) ARP [RFC2225]

   o  HARP (High-Performance Parallel Interface ARP) [RFC2834] [RFC2835]

   o  Dual MAC (Media Access Control) FDDI (Fiber Distributed Data
      Interface) ARP [RFC1329]

   o  MAPOS (Multiple Access Protocol over Synchronous Optical Network/
      Synchronous Digital Hierarchy) ARP [RFC2176]

   o  FC (Fibre Channel) ARP [RFC4338]

   o  DNS DHCID Resource Record [RFC4701]

   The IANA guidelines are given in Section 2.  Previously, no IANA
   guidance existed for such allocations.  The purpose of this document
   is to allow IANA to manage number assignments based on these
   guidelines in a consistent manner.

   This document also reserves some numbers for experimentation
   purposes.  These numbers are given in Section 3.

Arkko & Pignataro           Standards Track                     [Page 2]
RFC 5494                     ARP IANA Rules                   April 2009

2.  IANA Considerations

   The following rules apply to the fields of ARP:

   ar$hrd (16 bits) Hardware address space

      Requests for ar$hrd values below 256 or for a batch of more than
      one new value are made through Expert Review [RFC5226].

      Note that certain protocols, such as BOOTP and DHCPv4, employ
      these values within an 8-bit field.  The expert should determine
      that a need to allocate the new values exists and that the
      existing values are insufficient to represent the new hardware
      address types.  The expert should also determine the applicability
      of the request and assign values higher than 255 for requests that
      do not apply to BOOTP/DHCPv4.  Similarly, the expert should assign
      1-octet values for requests that apply to BOOTP/DHCPv4, as for
      example the "IPsec tunnel" with value 31 [RFC3456].  Conversely,
      ARP-only uses, without a foreseeable reason to use the same value
      in BOOTP/DHCPv4, should favor 2-octet values.

      Requests for individual new ar$hrd values that do not specify a
      value, or where the requested value is greater than 255, are made
      through First Come First Served [RFC5226].  The assignment will
      always result in a 2-octet value.

   ar$pro (16 bits) Protocol address space