Internet DRAFT - draft-hilliard-v6ops-host-addr-update

draft-hilliard-v6ops-host-addr-update







v6ops                                                        N. Hilliard
Internet-Draft                                                      INEX
BCP: 204                                                     J. Snijders
Updates: 7934 (if approved)                                          NTT
Intended status: Best Current Practice                     July 17, 2017
Expires: January 18, 2018


       Update for IPv6 Host Address Availability Recommendations
                draft-hilliard-v6ops-host-addr-update-00

Abstract

   The IPv6 Host Address Availability Recommendations Best Current
   Practice (RFC 7934), describes why IPv6 hosts should use multiple
   global addresses when attaching to a network.  This document updates
   RFC 7934 by removing a recommendation for networks to give the host
   the ability to use new addresses without requiring explicit requests.

Requirements Language

   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 [RFC2119].

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on January 18, 2018.

Copyright Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.





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   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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Updates to RFC7934  . . . . . . . . . . . . . . . . . . . . .   2
   3.  Rationale . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
   5.  Normative References  . . . . . . . . . . . . . . . . . . . .   3
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   4

1.  Introduction

   The IPv6 Host Address Availability Recommendations Best Current
   Practice document [RFC7934] describes why IPv6 hosts should use
   multiple global addresses when attaching to a network.  The
   recommendations in Section 8 of this document included the text:

      Due to the drawbacks imposed by requiring explicit requests for
      address space (see Section 4), it is RECOMMENDED that the network
      give the host the ability to use new addresses without requiring
      explicit requests.

   This text could be interpreted as recommending that IPv6 networks
   should not use not DHCPv6 [RFC3736], which provides new addresses in
   response to explicit requests.  This interpretation is based on the
   fact that a host which uses DHCPv6 IA_NA or IA_TA cannot use new
   addresses without requesting them from a DHCPv6 server on the
   network.

2.  Updates to RFC7934

   This document updates [RFC7934] to remove the second and third
   paragraphs of Section 8, so that the recommendations section of
   [RFC7934] reads in its entirety as follows:

      In order to avoid the problems described above and preserve the
      Internet's ability to support new applications that use more than
      one IPv6 address, it is RECOMMENDED that IPv6 network deployments
      provide multiple IPv6 addresses from each prefix to general-



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      purpose hosts.  To support future use cases, it is NOT RECOMMENDED
      to impose a hard limit on the size of the address pool assigned to
      a host.  Particularly, it is NOT RECOMMENDED to limit a host to
      only one IPv6 address per prefix.

3.  Rationale

   It has been argued in the v6ops Working Group that the first sentence
   second paragraph technically relegates the status of DHCPv6 to "NOT
   RECOMMENDED" on IPv6 networks, as it formally recommends that new
   addresses should be assigned without explicit requests.  This
   implicitly excludes all address assignment mechanisms, including
   DHCPv6, which are not handled by the host itself.  A change of this
   form to the status of DHCPv6 would be a serious and substantial
   change to the status of DHCPv6 at the IETF, and not one that could or
   should have been entertained without extensive debate as to whether
   it was an appropriate move to make.  This debate never happened and
   the justification provided in section 4 of [RFC7934] is insufficient
   per-se to warrant changing the recommendation status of such a
   widely-deployed Standards Track protocol as DHCPv6.

   The IPv6 self-selection addressing model does not necessarily suit
   the deployment requirements for many types of ipv6 networks,
   including enterprise, provider hosting, and various access network
   protocols (e.g.  docsis / gpon / ipoe); if the status of DHCPv6 were
   changed to "NOT RECOMMENDED", then there would be no recommended IETF
   model for stateful / operator-assigned IPv6 addressing, and this
   would leave a glaring hole in the IPv6 host specification.

   The subsequent sentences in the second paragraph provide alternatives
   to DHCPv6, and are superfluous in the absence of the first paragraph.

   The third paragraph notes that DHCPv6 stateful address assignment
   (IA_NA or IA_TA) can be used to provide multiple addresses when the
   host connects to the network, but does not mention that the host can
   issue multiple dhcpv6 requests, thereby allowing arbitrary numbers of
   assignments rather than the stated limit of approximately 30.  As the
   text in this paragraph is incorrect, it too has been removed.

4.  IANA Considerations

   There are no IANA considerations.

5.  Normative References







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   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC3736]  Droms, R., "Stateless Dynamic Host Configuration Protocol
              (DHCP) Service for IPv6", RFC 3736, DOI 10.17487/RFC3736,
              April 2004, <http://www.rfc-editor.org/info/rfc3736>.

   [RFC7934]  Colitti, L., Cerf, V., Cheshire, S., and D. Schinazi,
              "Host Address Availability Recommendations", BCP 204,
              RFC 7934, DOI 10.17487/RFC7934, July 2016,
              <http://www.rfc-editor.org/info/rfc7934>.

Authors' Addresses

   Nick Hilliard
   INEX
   4027 Kingswood Road
   Dublin  24
   IE

   Email: nick@inex.ie


   Job Snijders
   NTT Communications
   Theodorus Majofskistraat 100
   Amsterdam  1065 SZ
   The Netherlands

   Email: job@ntt.net



















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