Fixing the C-Flag in Extended Address Registration Option (EARO)
draft-ietf-6lo-updating-rfc-8928-05
| Document | Type | Active Internet-Draft (6lo WG) | |
|---|---|---|---|
| Authors | Pascal Thubert , Adnan Rashid | ||
| Last updated | 2025-07-09 (Latest revision 2025-06-26) | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Intended RFC status | Proposed Standard | ||
| Formats | |||
| Reviews | |||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | Submitted to IESG for Publication | |
| Document shepherd | Carles Gomez | ||
| Shepherd write-up | Show Last changed 2025-05-19 | ||
| IESG | IESG state | RFC Ed Queue | |
| Action Holders |
(None)
|
||
| Consensus boilerplate | Yes | ||
| Telechat date | (None) | ||
| Responsible AD | Éric Vyncke | ||
| Send notices to | carles.gomez@upc.edu | ||
| IANA | IANA review state | Version Changed - Review Needed | |
| IANA action state | RFC-Ed-Ack | ||
| RFC Editor | RFC Editor state | EDIT | |
| Details |
draft-ietf-6lo-updating-rfc-8928-05
6lo P. Thubert
Internet-Draft
Updates: 8928 (if approved) A. Rashid
Intended status: Standards Track Politecnico di Bari
Expires: 28 December 2025 26 June 2025
Fixing the C-Flag in Extended Address Registration Option (EARO)
draft-ietf-6lo-updating-rfc-8928-05
Abstract
This document updates “Address-Protected Neighbor Discovery for Low-
Power and Lossy Networks” (RFC 8928) by changing the position of the
C-flag in the Extended Address Registration Option (EARO) and
registering it with IANA.
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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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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 28 December 2025.
Copyright Notice
Copyright (c) 2025 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 (https://trustee.ietf.org/
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Please review these documents carefully, as they describe your rights
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provided without warranty as described in the Revised BSD License.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
2.1. Requirements Language . . . . . . . . . . . . . . . . . . 2
2.2. References . . . . . . . . . . . . . . . . . . . . . . . 2
2.3. Acronyms . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Updating RFC 8928 . . . . . . . . . . . . . . . . . . . . . . 3
4. Security Considerations . . . . . . . . . . . . . . . . . . . 5
5. Operational Considerations . . . . . . . . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
6.1. Bit Position of the C-flag . . . . . . . . . . . . . . . 5
7. Normative References . . . . . . . . . . . . . . . . . . . . 6
8. Informative References . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
The Address-Protected Neighbor Discovery for Low-Power and Lossy
Networks (AP-ND) [RFC8928] defined the C-flag in EARO. It is used to
indicate that the Registration Ownership Verifier (ROVR) field
contains a Crypto-ID and that the 6LoWPAN Node (6LN) may be
challenged for ownership of the registered address. Initially
[RFC8928] defined the C-flag in the EARO in bit position 3; later
[RFC9685] defined the P-Field in bits 2 and 3 of the EARO flags field
with proper IANA registration, causing an overlap with Figure 1 of
[RFC8928] which depicts the location of the C-flag.
This specification updates [RFC8928] by repositioning the C-flag as
bit 1 of the EARO flags field, thereby preventing conflicts.
2. Terminology
2.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2.2. References
This document uses terms and concepts that are discussed in
IPv6-Neighbor Discovery (ND) [RFC4861], [RFC4862], as well as
6LoWPAN-ND [RFC6775], [RFC8505], [RFC8928], [RFC8929], [RFC9685], and
[I-D.ietf-6lo-prefix-registration].
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2.3. Acronyms
This document uses the following abbreviations:
*6LN:* 6LoWPAN Node
*EARO:* Extended Address Registration Option
*ND:* Neighbor Discovery
*RATInd:* Registered Address Type Indicator
*ROVR:* Registration Ownership Verifier
3. Updating RFC 8928
[RFC8928] incorrectly refers to the Extended Address Registration
Option (EARO) as the Enhanced Address Registration Option. This
specification corrects this terminology throughout the document.
In [RFC8928], the C-flag is specified in the EARO flags field at bit
position 3 (as depicted in Figure 1 of [RFC8928]); however, [RFC8928]
fails to register its position with IANA. Later, [RFC9685] defined
the P-Field in bits 2 and 3 of the EARO flags field and obtained
proper IANA registration, but this introduced an overlap with the
representation in [RFC8928]. To resolve the conflict, this
specification updates [RFC8928] by repositioning the C-flag to bit 1
of the EARO flags field, ensuring there are no overlapping
definitions.
Figure 1 replaces Figure 1 in [RFC8928] in the case of an EARO used
in an NS message.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |F|Prefix Length| Opaque |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|r|C| P | I |R|T| TID | Registration Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
... Registration Ownership Verifier (ROVR) ...
| (64, 128, 192, or 256 bits) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Extended Address Registration Option (EARO) Format for
use in NS messages
Figure 2 replaces Figure 1 in [RFC8928] in the case of an EARO used
in an NA message. The difference between the two formats is in the
usage of bits 16 to 23.
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | r | Status | Opaque |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|r|C| P | I |R|T| TID | Registration Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
... Registration Ownership Verifier (ROVR) ...
| (64, 128, 192, or 256 bits) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Extended Address Registration Option (EARO) Format for
use in NA messages
Option fields of interest for this specification:
*Type:* 33
*Length:* Defined in [RFC8505].
*F:* Defined in [I-D.ietf-6lo-prefix-registration]
*Prefix Length* Defined in [I-D.ietf-6lo-prefix-registration]
*Status:* 6-bit unsigned integer. This field is used in NA(EARO)
response messages only to indicate the status of a registration.
This field is defined in [RFC8505] and resized by [RFC9010]. The
values for the Status field are available in [IANA.ICMP.ARO.STAT].
This field MUST be set to 0 in NS(EARO) messages unless the
registration is for a prefix, in which case the F-flag is set and
the prefix length is provided.
*Opaque:* Defined in [RFC8505]
*r (reserved):* 1-bit reserved field in NS(EARO) and NA(EARO) as
depicted in Figure 1 and Figure 2. 2-bit reserved field (most
significant bits of Status filed) in NA(EARO) as depicted in
Figure 2. All reserved field MUST be set to zero by the sender
and MUST be ignored by the receiver.
*C:* 1-bit flag, moved from its position in Figure 1 of [RFC8928].
It is set to indicate that the ROVR field contains a Crypto-ID and
that the 6LN MAY be challenged for ownership.
*P:* 2-bit field for Registered Address Type Indicator (RATInd).
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Indicates whether the registered address is unicast, multicast, or
anycast, or derived from the registered unicast prefix. Used to
transport the RATInd in different protocols. The values for the
RATInd field are available in [IANA.ICMP.ARO.P-FIELD].
*I:* Defined in [RFC8505]
*R:* Defined in [RFC8505]
*T:* Defined in [RFC8505]
*TID (Transaction ID):* Defined in [RFC8505]
*Registration Lifetime:* Defined in [RFC8505]
*Registration Ownership Verifier (ROVR):* Defined in [RFC8505].
Variable length field, used to verify who "owns" a registered IPv6
address. When the C-flag is set, this field contains a Crypto-ID
[RFC8928].
4. Security Considerations
This specification does not introduce any new security considerations
beyond those already discussed in [RFC8928] and [RFC8505].
5. Operational Considerations
The updates introduced in this document are not backward compatible.
However, given that there are no known implementations or deployments
of [RFC8928], this document do not require any transition plan.
6. IANA Considerations
6.1. Bit Position of the C-flag
IANA is requested to reference this RFC in addition to [RFC8928] when
updating the "Address Registration Option Flags" [IANA.ICMP.ARO.FLG]
registry under the heading "Internet Control Message Protocol version
6 (ICMPv6) Parameters" as specified in Table 1:
+---------------+-------------+------------------------+
| EARO flag | Description | Reference |
+---------------+-------------+------------------------+
| 1 (suggested) | C-Flag | RFC XXXX and [RFC8928] |
+---------------+-------------+------------------------+
Table 1: Bit Position of the C-flag
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7. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
DOI 10.17487/RFC4861, September 2007,
<https://www.rfc-editor.org/info/rfc4861>.
[RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
Address Autoconfiguration", RFC 4862,
DOI 10.17487/RFC4862, September 2007,
<https://www.rfc-editor.org/info/rfc4862>.
[RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C.
Bormann, "Neighbor Discovery Optimization for IPv6 over
Low-Power Wireless Personal Area Networks (6LoWPANs)",
RFC 6775, DOI 10.17487/RFC6775, November 2012,
<https://www.rfc-editor.org/info/rfc6775>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8505] Thubert, P., Ed., Nordmark, E., Chakrabarti, S., and C.
Perkins, "Registration Extensions for IPv6 over Low-Power
Wireless Personal Area Network (6LoWPAN) Neighbor
Discovery", RFC 8505, DOI 10.17487/RFC8505, November 2018,
<https://www.rfc-editor.org/info/rfc8505>.
[RFC8928] Thubert, P., Ed., Sarikaya, B., Sethi, M., and R. Struik,
"Address-Protected Neighbor Discovery for Low-Power and
Lossy Networks", RFC 8928, DOI 10.17487/RFC8928, November
2020, <https://www.rfc-editor.org/info/rfc8928>.
[RFC9010] Thubert, P., Ed. and M. Richardson, "Routing for RPL
(Routing Protocol for Low-Power and Lossy Networks)
Leaves", RFC 9010, DOI 10.17487/RFC9010, April 2021,
<https://www.rfc-editor.org/info/rfc9010>.
[RFC9685] Thubert, P., Ed., "Listener Subscription for IPv6 Neighbor
Discovery Multicast and Anycast Addresses", RFC 9685,
DOI 10.17487/RFC9685, November 2024,
<https://www.rfc-editor.org/info/rfc9685>.
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[I-D.ietf-6lo-prefix-registration]
Thubert, P., "IPv6 Neighbor Discovery Prefix
Registration", Work in Progress, Internet-Draft, draft-
ietf-6lo-prefix-registration-13, 6 June 2025,
<https://datatracker.ietf.org/doc/html/draft-ietf-6lo-
prefix-registration-13>.
[IANA.ICMP.ARO.FLG]
IANA, "IANA Registry for the Address Registration Option
Flags", IANA, https://www.iana.org/assignments/icmpv6-
parameters/icmpv6-parameters.xhtml#icmpv6-adress-
registration-option-flags.
[IANA.ICMP.ARO.STAT]
IANA, "IANA Registry for the Address Registration Option
Status Value", IANA, https://www.iana.org/assignments/
icmpv6-parameters/icmpv6-parameters.xhtml#address-
registration.
[IANA.ICMP.ARO.P-FIELD]
IANA, "IANA Registry for the Address Registration Option
Status Value", IANA, https://www.iana.org/assignments/
icmpv6-parameters/icmpv6-parameters.xhtml#p-field-values.
8. Informative References
[RFC8929] Thubert, P., Ed., Perkins, C.E., and E. Levy-Abegnoli,
"IPv6 Backbone Router", RFC 8929, DOI 10.17487/RFC8929,
November 2020, <https://www.rfc-editor.org/info/rfc8929>.
Authors' Addresses
Pascal Thubert
06330 Roquefort-les-Pins
France
Email: pascal.thubert@gmail.com
Adnan Rashid
Politecnico di Bari
Via Edoardo Orabona 4
70126 Bari
Italy
Email: adnan.rashid@poliba.it
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