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
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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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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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