rfc9927.original   rfc9927.txt 
6lo P. Thubert Internet Engineering Task Force (IETF) P. Thubert
Internet-Draft Request for Comments: 9927
Updates: 8928 (if approved) A. Rashid Updates: 8928 A. Rashid
Intended status: Standards Track Politecnico di Bari Category: Standards Track Politecnico di Bari
Expires: 28 December 2025 26 June 2025 ISSN: 2070-1721 January 2026
Fixing the C-Flag in Extended Address Registration Option (EARO) Fixing the C-Flag in the Extended Address Registration Option (EARO)
draft-ietf-6lo-updating-rfc-8928-05
Abstract Abstract
This document updates “Address-Protected Neighbor Discovery for Low- This document updates "Address-Protected Neighbor Discovery for Low-
Power and Lossy Networks” (RFC 8928) by changing the position of the Power and Lossy Networks" (RFC 8928) by changing the position of the
C-flag in the Extended Address Registration Option (EARO) and C-flag in the Extended Address Registration Option (EARO) and
registering it with IANA. registering it with IANA.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
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
working documents as Internet-Drafts. The list of current Internet-
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Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on 28 December 2025. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9927.
Copyright Notice Copyright Notice
Copyright (c) 2025 IETF Trust and the persons identified as the Copyright (c) 2026 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology
2.1. Requirements Language . . . . . . . . . . . . . . . . . . 2 2.1. Requirements Language
2.2. References . . . . . . . . . . . . . . . . . . . . . . . 2 2.2. Terminology
2.3. Acronyms . . . . . . . . . . . . . . . . . . . . . . . . 3 2.3. Acronyms
3. Updating RFC 8928 . . . . . . . . . . . . . . . . . . . . . . 3 3. Updating RFC 8928
4. Security Considerations . . . . . . . . . . . . . . . . . . . 5 4. Security Considerations
5. Operational Considerations . . . . . . . . . . . . . . . . . 5 5. Operational Considerations
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 6. IANA Considerations
6.1. Bit Position of the C-flag . . . . . . . . . . . . . . . 5 6.1. Bit Position of the C-flag
7. Normative References . . . . . . . . . . . . . . . . . . . . 6 7. References
8. Informative References . . . . . . . . . . . . . . . . . . . 7 7.1. Normative References
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 7.2. Informative References
Authors' Addresses
1. Introduction 1. Introduction
The Address-Protected Neighbor Discovery for Low-Power and Lossy The Address-Protected Neighbor Discovery for Low-Power and Lossy
Networks (AP-ND) [RFC8928] defined the C-flag in EARO. It is used to Networks (AP-ND) [RFC8928] defined the C-flag in EARO. It is used to
indicate that the Registration Ownership Verifier (ROVR) field indicate that the Registration Ownership Verifier (ROVR) field
contains a Crypto-ID and that the 6LoWPAN Node (6LN) may be contains a Crypto-ID and that the 6LoWPAN Node (6LN) may be
challenged for ownership of the registered address. Initially challenged for ownership of the registered address. Initially,
[RFC8928] defined the C-flag in the EARO in bit position 3; later [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 [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 with proper IANA registration, causing an overlap with Figure 1 of
[RFC8928] which depicts the location of the C-flag. [RFC8928], which depicts the location of the C-flag.
This specification updates [RFC8928] by repositioning the C-flag as This specification updates [RFC8928] by repositioning the C-flag as
bit 1 of the EARO flags field, thereby preventing conflicts. bit 1 of the EARO flags field, thereby preventing conflicts.
2. Terminology 2. Terminology
2.1. Requirements Language 2.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in
14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
2.2. References 2.2. Terminology
This document uses terms and concepts that are discussed in This document uses terms and concepts that are discussed in IPv6
IPv6-Neighbor Discovery (ND) [RFC4861], [RFC4862], as well as Neighbor Discovery (ND) [RFC4861], [RFC4862], as well as 6LoWPAN-ND
6LoWPAN-ND [RFC6775], [RFC8505], [RFC8928], [RFC8929], [RFC9685], and [RFC6775], [RFC8505], [RFC8928], [RFC8929], [RFC9685], and [RFC9926].
[I-D.ietf-6lo-prefix-registration].
2.3. Acronyms 2.3. Acronyms
This document uses the following abbreviations: This document uses the following abbreviations:
*6LN:* 6LoWPAN Node *6LN:* 6LoWPAN Node
*EARO:* Extended Address Registration Option *EARO:* Extended Address Registration Option
*ND:* Neighbor Discovery *ND:* Neighbor Discovery
*RATInd:* Registered Address Type Indicator *RATInd:* Registered Address Type Indicator
*ROVR:* Registration Ownership Verifier *ROVR:* Registration Ownership Verifier
3. Updating RFC 8928 3. Updating RFC 8928
[RFC8928] incorrectly refers to the Extended Address Registration [RFC8928] incorrectly refers to the Extended Address Registration
Option (EARO) as the Enhanced Address Registration Option. This Option (EARO) as the Enhanced Address Registration Option. This
specification corrects this terminology throughout the document. specification corrects this terminology throughout the document.
In [RFC8928], the C-flag is specified in the EARO flags field at bit 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] position 3 (as depicted in Figure 1 of [RFC8928]); however, [RFC8928]
skipping to change at page 3, line 48 skipping to change at line 141
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|r|C| P | I |R|T| TID | Registration Lifetime | |r|C| P | I |R|T| TID | Registration Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
... Registration Ownership Verifier (ROVR) ... ... Registration Ownership Verifier (ROVR) ...
| (64, 128, 192, or 256 bits) | | (64, 128, 192, or 256 bits) |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Extended Address Registration Option (EARO) Format for Figure 1: Extended Address Registration Option (EARO) Format for
use in NS messages Use in NS Messages
Figure 2 replaces Figure 1 in [RFC8928] in the case of an EARO used 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 in an NA message. The difference between the two formats is in the
usage of bits 16 to 23. usage of bits 16 to 23.
0 1 2 3 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 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 | | Type | Length | r | Status | Opaque |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|r|C| P | I |R|T| TID | Registration Lifetime | |r|C| P | I |R|T| TID | Registration Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
... Registration Ownership Verifier (ROVR) ... ... Registration Ownership Verifier (ROVR) ...
| (64, 128, 192, or 256 bits) | | (64, 128, 192, or 256 bits) |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Extended Address Registration Option (EARO) Format for Figure 2: Extended Address Registration Option (EARO) Format for
use in NA messages Use in NA Messages
Option fields of interest for this specification: Option fields of interest for this specification:
*Type:* 33 *Type:* 33
*Length:* Defined in [RFC8505]. *Length:* Defined in [RFC8505]
*F:* Defined in [I-D.ietf-6lo-prefix-registration] *F:* Defined in [RFC9926]
*Prefix Length* Defined in [I-D.ietf-6lo-prefix-registration] *Prefix Length* Defined in [RFC9926]
*Status:* 6-bit unsigned integer. This field is used in NA(EARO) *Status:* 6-bit unsigned integer. This field is used in NA(EARO)
response messages only to indicate the status of a registration. response messages only to indicate the status of a registration.
This field is defined in [RFC8505] and resized by [RFC9010]. The This field is defined in [RFC8505] and resized by [RFC9010]. The
values for the Status field are available in [IANA.ICMP.ARO.STAT]. 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 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 registration is for a prefix, in which case the F-flag is set and
the prefix length is provided. the prefix length is provided.
*Opaque:* Defined in [RFC8505] *Opaque:* Defined in [RFC8505]
skipping to change at page 5, line 4 skipping to change at line 194
depicted in Figure 1 and Figure 2. 2-bit reserved field (most depicted in Figure 1 and Figure 2. 2-bit reserved field (most
significant bits of Status filed) in NA(EARO) as depicted in significant bits of Status filed) in NA(EARO) as depicted in
Figure 2. All reserved field MUST be set to zero by the sender Figure 2. All reserved field MUST be set to zero by the sender
and MUST be ignored by the receiver. and MUST be ignored by the receiver.
*C:* 1-bit flag, moved from its position in Figure 1 of [RFC8928]. *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 It is set to indicate that the ROVR field contains a Crypto-ID and
that the 6LN MAY be challenged for ownership. that the 6LN MAY be challenged for ownership.
*P:* 2-bit field for Registered Address Type Indicator (RATInd). *P:* 2-bit field for Registered Address Type Indicator (RATInd).
Indicates whether the registered address is unicast, multicast,
Indicates whether the registered address is unicast, multicast, or
anycast, or derived from the registered unicast prefix. Used to anycast, or derived from the registered unicast prefix. Used to
transport the RATInd in different protocols. The values for the transport the RATInd in different protocols. The values for the
RATInd field are available in [IANA.ICMP.ARO.P-FIELD]. RATInd field are available in [IANA.ICMP.ARO.P-FIELD].
*I:* Defined in [RFC8505] *I:* Defined in [RFC8505]
*R:* Defined in [RFC8505] *R:* Defined in [RFC8505]
*T:* Defined in [RFC8505] *T:* Defined in [RFC8505]
*TID (Transaction ID):* Defined in [RFC8505] *TID (Transaction ID):* Defined in [RFC8505]
*Registration Lifetime:* Defined in [RFC8505] *Registration Lifetime:* Defined in [RFC8505]
*Registration Ownership Verifier (ROVR):* Defined in [RFC8505]. *Registration Ownership Verifier (ROVR):* Defined in [RFC8505].
Variable length field, used to verify who "owns" a registered IPv6 Variable-length field used to verify who "owns" a registered IPv6
address. When the C-flag is set, this field contains a Crypto-ID address. When the C-flag is set, this field contains a Crypto-ID
[RFC8928]. [RFC8928].
4. Security Considerations 4. Security Considerations
This specification does not introduce any new security considerations This specification does not introduce any new security considerations
beyond those already discussed in [RFC8928] and [RFC8505]. beyond those already discussed in [RFC8928] and [RFC8505].
5. Operational Considerations 5. Operational Considerations
The updates introduced in this document are not backward compatible. The updates introduced in this document are not backward compatible.
However, given that there are no known implementations or deployments However, given that there are no known implementations or deployments
of [RFC8928], this document do not require any transition plan. of [RFC8928], this document does not require any transition plan.
6. IANA Considerations 6. IANA Considerations
6.1. Bit Position of the C-flag 6.1. Bit Position of the C-flag
IANA is requested to reference this RFC in addition to [RFC8928] when IANA has updated the "Address Registration Option Flags"
updating the "Address Registration Option Flags" [IANA.ICMP.ARO.FLG] [IANA.ICMP.ARO.FLG] registry in the "Internet Control Message
registry under the heading "Internet Control Message Protocol version Protocol version 6 (ICMPv6) Parameters" registry group as specified
6 (ICMPv6) Parameters" as specified in Table 1: in Table 1 so this document is referenced in addition to [RFC8928]
for bit number 1:
+---------------+-------------+------------------------+ +============+=============+========================+
| EARO flag | Description | Reference | | Bit Number | Description | Reference |
+---------------+-------------+------------------------+ +============+=============+========================+
| 1 (suggested) | C-Flag | RFC XXXX and [RFC8928] | | 1 | C-Flag | RFC 9927 and [RFC8928] |
+---------------+-------------+------------------------+ +------------+-------------+------------------------+
Table 1: Bit Position of the C-flag Table 1: Bit Position of the C-flag
7. Normative References 7. References
7.1. Normative References
[IANA.ICMP.ARO.FLG]
IANA, "Address Registration Option Flags",
<https://www.iana.org/assignments/icmpv6-parameters>.
[IANA.ICMP.ARO.P-FIELD]
IANA, "P-Field Values",
<https://www.iana.org/assignments/icmpv6-parameters>.
[IANA.ICMP.ARO.STAT]
IANA, "Address Registration Option Status Values",
<https://www.iana.org/assignments/icmpv6-parameters>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
DOI 10.17487/RFC4861, September 2007, DOI 10.17487/RFC4861, September 2007,
<https://www.rfc-editor.org/info/rfc4861>. <https://www.rfc-editor.org/info/rfc4861>.
skipping to change at page 7, line 5 skipping to change at line 305
[RFC9010] Thubert, P., Ed. and M. Richardson, "Routing for RPL [RFC9010] Thubert, P., Ed. and M. Richardson, "Routing for RPL
(Routing Protocol for Low-Power and Lossy Networks) (Routing Protocol for Low-Power and Lossy Networks)
Leaves", RFC 9010, DOI 10.17487/RFC9010, April 2021, Leaves", RFC 9010, DOI 10.17487/RFC9010, April 2021,
<https://www.rfc-editor.org/info/rfc9010>. <https://www.rfc-editor.org/info/rfc9010>.
[RFC9685] Thubert, P., Ed., "Listener Subscription for IPv6 Neighbor [RFC9685] Thubert, P., Ed., "Listener Subscription for IPv6 Neighbor
Discovery Multicast and Anycast Addresses", RFC 9685, Discovery Multicast and Anycast Addresses", RFC 9685,
DOI 10.17487/RFC9685, November 2024, DOI 10.17487/RFC9685, November 2024,
<https://www.rfc-editor.org/info/rfc9685>. <https://www.rfc-editor.org/info/rfc9685>.
[I-D.ietf-6lo-prefix-registration] [RFC9926] Thubert, P., Ed., "IPv6 Neighbor Discovery Prefix
Thubert, P., "IPv6 Neighbor Discovery Prefix Registration", RFC 9926, DOI 10.17487/RFC9926, January
Registration", Work in Progress, Internet-Draft, draft- 2026, <https://www.rfc-editor.org/info/rfc9926>.
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 7.2. Informative References
[RFC8929] Thubert, P., Ed., Perkins, C.E., and E. Levy-Abegnoli, [RFC8929] Thubert, P., Ed., Perkins, C.E., and E. Levy-Abegnoli,
"IPv6 Backbone Router", RFC 8929, DOI 10.17487/RFC8929, "IPv6 Backbone Router", RFC 8929, DOI 10.17487/RFC8929,
November 2020, <https://www.rfc-editor.org/info/rfc8929>. November 2020, <https://www.rfc-editor.org/info/rfc8929>.
Authors' Addresses Authors' Addresses
Pascal Thubert Pascal Thubert
06330 Roquefort-les-Pins 06330 Roquefort-les-Pins
France France
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