Roquefort-les-Pins 06330 France pascal.thubert@gmail.com

Politecnico di Bari

Via Edoardo Orabona 4 Bari 70126 Italy adnan.rashid@poliba.it

INT 6lo 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 is an Internet Standards Track document. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 7841. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at .

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Table of Contents

• .  Introduction
• .  Terminology
  • .  Requirements Language
  • .  Related Documents
  • .  Acronyms
• .  Updating RFC 8928
• .  Security Considerations
• .  Operational Considerations
• .  IANA Considerations
  • .  Bit Position of the C-flag
• .  References
  • .  Normative References
  • .  Informative References
• Authors' Addresses

Introduction The Address-Protected Neighbor Discovery for Low-Power and Lossy Networks (AP-ND) 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, defined the C-flag in the EARO in bit position 3; later, 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 , which depicts the location of the C-flag. This specification updates by repositioning the C-flag as bit 1 of the EARO flags field, thereby preventing conflicts.

Terminology

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 when, and only when, they appear in all capitals, as shown here.

Related Documents This document uses terms and concepts that are discussed in IPv6 Neighbor Discovery (ND) , , as well as 6LoWPAN-ND , , , , , and .

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

Updating RFC 8928 incorrectly refers to the Extended Address Registration Option (EARO) as the Enhanced Address Registration Option. This specification corrects this terminology throughout the document. In , the C-flag is specified in the EARO flags field at bit position 3 (as depicted in Figure 1 of ); however, fails to register its position with IANA. Later, 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 . To resolve the conflict, this specification updates by repositioning the C-flag to bit 1 of the EARO flags field, ensuring there are no overlapping definitions. replaces Figure 1 in in the case of an EARO used in an NS message.

Extended Address Registration Option (EARO) Format for Use in NS Messages 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) | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

replaces Figure 1 in 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.

Extended Address Registration Option (EARO) Format for Use in NA Messages 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) | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Option fields of interest for this specification:

Type:

33

Length:

Defined in

F:

Defined in

Prefix Length

Defined in

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 and resized by . The values for the Status field are available in . 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

r (reserved):

1-bit reserved field in NS(EARO) and NA(EARO) as depicted in and . 2-bit reserved field (most significant bits of Status filed) in NA(EARO) as depicted in . 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 . 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). Indicates whether the registered address is unicast, multicast, 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 .

I:

Defined in

R:

Defined in

T:

Defined in

TID (Transaction ID):

Defined in

Registration Lifetime:

Defined in

Registration Ownership Verifier (ROVR):

Defined in . Variable-length field used to verify who "owns" a registered IPv6 address. When the C-flag is set, this field contains a Crypto-ID .

Security Considerations This specification does not introduce any new security considerations beyond those already discussed in and .

Operational Considerations The updates introduced in this document are not backward compatible. However, given that there are no known implementations or deployments of , this document does not require any transition plan.

IANA Considerations

Bit Position of the C-flag IANA has updated the "Address Registration Option Flags" registry in the "Internet Control Message Protocol version 6 (ICMPv6) Parameters" registry group as specified in so this document is referenced in addition to for bit number 1: Bit Position of the C-flag

Bit Number	Description	Reference
1	C-Flag	RFC 9927 and

References Normative References IANA IANA IANA In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. This document specifies the Neighbor Discovery protocol for IP Version 6. IPv6 nodes on the same link use Neighbor Discovery to discover each other's presence, to determine each other's link-layer addresses, to find routers, and to maintain reachability information about the paths to active neighbors. [STANDARDS-TRACK] This document specifies the steps a host takes in deciding how to autoconfigure its interfaces in IP version 6. The autoconfiguration process includes generating a link-local address, generating global addresses via stateless address autoconfiguration, and the Duplicate Address Detection procedure to verify the uniqueness of the addresses on a link. [STANDARDS-TRACK] The IETF work in IPv6 over Low-power Wireless Personal Area Network (6LoWPAN) defines 6LoWPANs such as IEEE 802.15.4. This and other similar link technologies have limited or no usage of multicast signaling due to energy conservation. In addition, the wireless network may not strictly follow the traditional concept of IP subnets and IP links. IPv6 Neighbor Discovery was not designed for non- transitive wireless links, as its reliance on the traditional IPv6 link concept and its heavy use of multicast make it inefficient and sometimes impractical in a low-power and lossy network. This document describes simple optimizations to IPv6 Neighbor Discovery, its addressing mechanisms, and duplicate address detection for Low- power Wireless Personal Area Networks and similar networks. The document thus updates RFC 4944 to specify the use of the optimizations defined here. [STANDARDS-TRACK] RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings. This specification updates RFC 6775 -- the Low-Power Wireless Personal Area Network (6LoWPAN) Neighbor Discovery specification -- to clarify the role of the protocol as a registration technique and simplify the registration operation in 6LoWPAN routers, as well as to provide enhancements to the registration capabilities and mobility detection for different network topologies, including the Routing Registrars performing routing for host routes and/or proxy Neighbor Discovery in a low-power network. This document updates the IPv6 over Low-Power Wireless Personal Area Network (6LoWPAN) Neighbor Discovery (ND) protocol defined in RFCs 6775 and 8505. The new extension is called Address-Protected Neighbor Discovery (AP-ND), and it protects the owner of an address against address theft and impersonation attacks in a Low-Power and Lossy Network (LLN). Nodes supporting this extension compute a cryptographic identifier (Crypto-ID), and use it with one or more of their Registered Addresses. The Crypto-ID identifies the owner of the Registered Address and can be used to provide proof of ownership of the Registered Addresses. Once an address is registered with the Crypto-ID and a proof of ownership is provided, only the owner of that address can modify the registration information, thereby enforcing Source Address Validation. This specification provides a mechanism for a host that implements a routing-agnostic interface based on IPv6 over Low-Power Wireless Personal Area Network (6LoWPAN) Neighbor Discovery to obtain reachability services across a network that leverages RFC 6550 for its routing operations. It updates RFCs 6550, 6775, and 8505. This document updates the 6LoWPAN extensions to IPv6 Neighbor Discovery (specified in RFCs 4861 and 8505) to enable a listener to subscribe to an IPv6 anycast or multicast address. This document also updates the Routing Protocol for Low-Power and Lossy Networks (RPL) (specified in RFCs 6550 and 6553) to add a new Non-Storing multicast mode and new support for anycast addresses in Storing and Non-Storing modes. This document extends RFC 9010 to enable a 6LoWPAN Router (6LR) to inject the anycast and multicast addresses in RPL. Informative References This document updates RFCs 6775 and 8505 in order to enable proxy services for IPv6 Neighbor Discovery by Routing Registrars called "Backbone Routers". Backbone Routers are placed along the wireless edge of a backbone and federate multiple wireless links to form a single Multi-Link Subnet (MLSN).

Authors' Addresses

Roquefort-les-Pins 06330 France pascal.thubert@gmail.com

Politecnico di Bari

Via Edoardo Orabona 4 Bari 70126 Italy adnan.rashid@poliba.it