draft-ietf-6man-ipv6only-flag-00.txt   draft-ietf-6man-ipv6only-flag-01.txt 
Network Working Group R. Hinden Network Working Group R. Hinden
Internet-Draft Check Point Software Internet-Draft Check Point Software
Updates: 5175 (if approved) B. Carpenter Updates: 5175 (if approved) B. Carpenter
Intended status: Standards Track Univ. of Auckland Intended status: Standards Track Univ. of Auckland
Expires: November 25, 2018 May 24, 2018 Expires: January 1, 2019 June 30, 2018
IPv6 Router Advertisement IPv6-Only Flag IPv6 Router Advertisement IPv6-Only Flag
draft-ietf-6man-ipv6only-flag-00 draft-ietf-6man-ipv6only-flag-01
Abstract Abstract
This document specifies a Router Advertisement Flag to indicate to This document specifies a Router Advertisement Flag to indicate to
hosts that the administrator has configured the router to advertise hosts that the administrator has configured the router to advertise
that the link is IPv6-Only. This document updates RFC5175. that the link is IPv6-Only. This document updates RFC5175.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on November 25, 2018. This Internet-Draft will expire on January 1, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3 2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. Applicability Statements . . . . . . . . . . . . . . . . . . 4 3. Applicability Statements . . . . . . . . . . . . . . . . . . 4
4. IPv6-Only Definition . . . . . . . . . . . . . . . . . . . . 4 4. IPv6-Only Definition . . . . . . . . . . . . . . . . . . . . 4
5. IPv6-Only Flag . . . . . . . . . . . . . . . . . . . . . . . 4 5. IPv6-Only Flag . . . . . . . . . . . . . . . . . . . . . . . 4
6. Router and Operational Considerations . . . . . . . . . . . . 5 6. Router and Operational Considerations . . . . . . . . . . . . 5
7. Host Behavior Considerations . . . . . . . . . . . . . . . . 6 7. Host Behavior Considerations . . . . . . . . . . . . . . . . 6
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
9. Security Considerations . . . . . . . . . . . . . . . . . . . 6 9. Security Considerations . . . . . . . . . . . . . . . . . . . 7
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 7 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 7
11. Change log [RFC Editor: Please remove] . . . . . . . . . . . 7 11. Change log [RFC Editor: Please remove] . . . . . . . . . . . 8
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
12.1. Normative References . . . . . . . . . . . . . . . . . . 9 12.1. Normative References . . . . . . . . . . . . . . . . . . 9
12.2. Informative References . . . . . . . . . . . . . . . . . 9 12.2. Informative References . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction 1. Introduction
This document specifies a Router Advertisement Flag to indicate to This document specifies a Router Advertisement Flag to indicate to
hosts that the administrator has configured the router to advertise hosts that the administrator has configured the router to advertise
that the link is IPv6-Only. The flag does not apply to non-default that the link is IPv6-Only. The flag does not apply to non-default
IPv6 routers. IPv6 routers.
Hosts that support IPv4 and IPv6, usually called dual stack hosts, Hosts that support IPv4 and IPv6, usually called dual stack hosts,
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a specific IPv4 link-local service, can continue to do so. This is a specific IPv4 link-local service, can continue to do so. This is
consistent with the SHOULD language in this document. consistent with the SHOULD language in this document.
Administrators SHOULD only use this mechanism if they are certain Administrators SHOULD only use this mechanism if they are certain
that the link is IPv6-Only. For example, in cases where there is a that the link is IPv6-Only. For example, in cases where there is a
need to continue to use IPv4 or there are IPv4 only routers, setting need to continue to use IPv4 or there are IPv4 only routers, setting
this flag to 1 is a configuration error. this flag to 1 is a configuration error.
4. IPv6-Only Definition 4. IPv6-Only Definition
IPv6-Only is defined to mean that only IPv6 is running on the link. IPv6-Only is defined to mean that no other versions of internet
This includes: protocol than IPv6 are running directly on the link. Today this
effectively simply means that IPv4 is not running on the link, and it
includes:
* No IPv4 traffic on the Link * No IPv4 traffic on the Link
* No IPv4 routers on the Link * No IPv4 routers on the Link
* No DHCPv4 servers on the Link * No DHCPv4 servers on the Link
* No IPv4 accessible services on the Link * No IPv4 accessible services on the Link
* All IPv4 and ARP traffic may be blocked at Layer 2 by the * All IPv4 and ARP traffic may be blocked at Layer 2 by the
administrator administrator
It is expected that on IPv6-Only networks it will be common for It is expected that on IPv6-Only networks it will be common for
access to IPv4 external services to be reached by techniques such as access to IPv4 external services to be reached by techniques such as
NAT64 [RFC6146] and DNS64 [RFC6147] at the edge of the network. This NAT64 [RFC6146] and DNS64 [RFC6147] at the edge of the network. This
is beyond the scope of this document. is beyond the scope of this document.
Note that IPv6-Only provides no information about other network
protocols than IP running directly over the link layer. It is out of
scope of this specification whether any such protocol is running on
the link or whether any protocol is tunneled over IPv6.
5. IPv6-Only Flag 5. IPv6-Only Flag
RFC5175 currently defines the flags in the NDP Router Advertisement RFC5175 currently defines the flags in the NDP Router Advertisement
message and these flags are registered in the IANA IPv6 ND Router message and these flags are registered in the IANA IPv6 ND Router
Advertisement flags Registry [IANA-RF]. This currently contains the Advertisement flags Registry [IANA-RF]. This currently contains the
following one-bit flags defined in published RFCs: following one-bit flags defined in published RFCs:
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|M|O|H|Prf|P|R|R| |M|O|H|Prf|P|R|R|
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In all of the above, the flag's value is considered valid for the In all of the above, the flag's value is considered valid for the
lifetime of the default router concerned, unless a subsequent RA lifetime of the default router concerned, unless a subsequent RA
delivers a different flag value. If a default router expires (i.e., delivers a different flag value. If a default router expires (i.e.,
no RA is received that refreshes its lifetime), the host must remove no RA is received that refreshes its lifetime), the host must remove
this router's flag value from consideration. If the result is that this router's flag value from consideration. If the result is that
all surviving default routers have the flag set to 1, the host SHOULD all surviving default routers have the flag set to 1, the host SHOULD
assume that the link is IPv6-Only. In other words, at any given assume that the link is IPv6-Only. In other words, at any given
time, the state of the flag as seen by the host is the logical AND of time, the state of the flag as seen by the host is the logical AND of
the flags sent by all unexpired default IPv6 routers. the flags sent by all unexpired default IPv6 routers.
This also means that if all default routers have set the flag, the
flag for the host is thereby set. If the lifetimes of all the
routers subsequently expire, then the state of the flag for the host
becomes cleared.
8. IANA Considerations 8. IANA Considerations
IANA is requested to assign the new Router Advertisement flag defined IANA is requested to assign the new Router Advertisement flag defined
in Section 5 of this document. Bit 6 is the next available bit in in Section 5 of this document. Bit 6 is the next available bit in
this registry, IANA is requested to use this bit unless there is a this registry, IANA is requested to use this bit unless there is a
reason to use another bit in this registry. reason to use another bit in this registry.
IANA is also requested to register this new flag bit in the IANA IPv6 IANA is also requested to register this new flag bit in the IANA IPv6
ND Router Advertisement flags Registry [IANA-RF]. ND Router Advertisement flags Registry [IANA-RF].
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traffic that might reveal the existence of a host and the correlation traffic that might reveal the existence of a host and the correlation
between its hardware and IPv4 addresses. between its hardware and IPv4 addresses.
10. Acknowledgments 10. Acknowledgments
A closely related proposal was published earlier as A closely related proposal was published earlier as
[I-D.ietf-sunset4-noipv4]. [I-D.ietf-sunset4-noipv4].
Helpful comments were received from Lorenzo Colitti, David Farmer, Helpful comments were received from Lorenzo Colitti, David Farmer,
Fernando Gont, Nick Hilliard, Erik Kline, Jen Linkova, Veronika Fernando Gont, Nick Hilliard, Erik Kline, Jen Linkova, Veronika
McKillop, Michael Richardson, Mark Smith, Barbara Stark, Ole Troan, McKillop, Michael Richardson, Mark Smith, Barbara Stark, Tatuya
James Woodyatt, and other members of the 6MAN working group. Jinmei, Ole Troan, James Woodyatt, and other members of the 6MAN
working group.
Bjoern Zeeb has also produced a variant of this proposal and proposed Bjoern Zeeb has also produced a variant of this proposal and proposed
an IPv6 transition plan in [I-D.bz-v4goawayflag]. an IPv6 transition plan in [I-D.bz-v4goawayflag].
11. Change log [RFC Editor: Please remove] 11. Change log [RFC Editor: Please remove]
draft-ietf-6man-ipv6only-flag-01, 2018-June-29:
* Added text to section that defines what IPv6-Only includes to
clarify that only other version of the Internet protocol are in
scope.
* Added clarification if the lifetime of all routers expire.
* Editorial changes.
draft-ietf-6man-ipv6only-flag-00, 2018-May-21: draft-ietf-6man-ipv6only-flag-00, 2018-May-21:
* Changed the file name to draft-ietf-6man-ipv6only-flag to match * Changed the file name to draft-ietf-6man-ipv6only-flag to match
the current tile and that it is a w.g. draft. the current tile and that it is a w.g. draft.
* Added new section that defines what IPv6-Only includes. * Added new section that defines what IPv6-Only includes.
* Expanded description of using Layer 2 filter to block IPv4 and * Expanded description of using Layer 2 filter to block IPv4 and
ARP traffic. ARP traffic.
* Editorial changes. * Editorial changes.
draft-hinden-ipv4flag-04, 2018-April-16: draft-hinden-ipv4flag-04, 2018-April-16:
* Changed the name of the document and flag to be the IPv6-Only * Changed the name of the document and flag to be the IPv6-Only
flag. flag.
* Rewrote text to make it affirmative that this is used by an * Rewrote text to make it affirmative that this is used by an
administrator to tell the hosts that the link is IPv6-Only. administrator to tell the hosts that the link is IPv6-Only.
 End of changes. 12 change blocks. 
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