< draft-ietf-6lo-rfc6775-update-06.txt		draft-ietf-6lo-rfc6775-update-07.txt >
	6lo P. Thubert, Ed.		6lo P. Thubert, Ed.
	Internet-Draft cisco		Internet-Draft cisco
	Updates: 6775 (if approved) E. Nordmark		Updates: 6775 (if approved) E. Nordmark
	Intended status: Standards Track		Intended status: Standards Track
	Expires: December 23, 2017 S. Chakrabarti		Expires: January 29, 2018 S. Chakrabarti
	June 21, 2017		July 28, 2017
	An Update to 6LoWPAN ND		An Update to 6LoWPAN ND
	draft-ietf-6lo-rfc6775-update-06		draft-ietf-6lo-rfc6775-update-07
	Abstract		Abstract
	This specification updates RFC 6775 - 6LoWPAN Neighbor Discovery, to		This specification updates RFC 6775 - 6LoWPAN Neighbor Discovery, to
	clarify the role of the protocol as a registration technique,		clarify the role of the protocol as a registration technique,
	simplify the registration operation in 6LoWPAN routers, as well as to		simplify the registration operation in 6LoWPAN routers, as well as to
	provide enhancements to the registration capabilities and mobility		provide enhancements to the registration capabilities and mobility
	detection for different network topologies including the backbone		detection for different network topologies including the backbone
	routers performing proxy Neighbor Discovery in a low power network.		routers performing proxy Neighbor Discovery in a low power network.
	skipping to change at page 1, line 37 ¶		skipping to change at page 1, line 37 ¶
	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 December 23, 2017.		This Internet-Draft will expire on January 29, 2018.
	Copyright Notice		Copyright Notice
	Copyright (c) 2017 IETF Trust and the persons identified as the		Copyright (c) 2017 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
	skipping to change at page 2, line 16 ¶		skipping to change at page 2, line 16 ¶
	described in the Simplified BSD License.		described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
	2. Applicability of Address Registration Options . . . . . . . . 3		2. Applicability of Address Registration Options . . . . . . . . 3
	3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4		3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
	4. Updating RFC 6775 . . . . . . . . . . . . . . . . . . . . . . 5		4. Updating RFC 6775 . . . . . . . . . . . . . . . . . . . . . . 5
	4.1. Extended Address Registration Option . . . . . . . . . . 6		4.1. Extended Address Registration Option . . . . . . . . . . 6
	4.2. Transaction ID . . . . . . . . . . . . . . . . . . . . . 6		4.2. Transaction ID . . . . . . . . . . . . . . . . . . . . . 6
	4.3. Owner Unique ID . . . . . . . . . . . . . . . . . . . . . 7		4.2.1. Comparing TID values . . . . . . . . . . . . . . . . 7
	4.4. Registering the Target Address . . . . . . . . . . . . . 7		4.3. Owner Unique ID . . . . . . . . . . . . . . . . . . . . . 8
	4.5. Link-Local Addresses and Registration . . . . . . . . . . 8		4.4. Registering the Target Address . . . . . . . . . . . . . 9
	4.6. Maintaining the Registration States . . . . . . . . . . . 9		4.5. Link-Local Addresses and Registration . . . . . . . . . . 9
	5. Detecting Enhanced ARO Capability Support . . . . . . . . . . 10		4.6. Maintaining the Registration States . . . . . . . . . . . 11
	6. Updated ND Options . . . . . . . . . . . . . . . . . . . . . 11		5. Detecting Enhanced ARO Capability Support . . . . . . . . . . 12
	6.1. The Enhanced Address Registration Option (EARO) . . . . . 11		6. Updated ND Options . . . . . . . . . . . . . . . . . . . . . 13
			6.1. The Enhanced Address Registration Option (EARO) . . . . . 13
	6.2. New 6LoWPAN capability Bits in the Capability Indication		6.2. New 6LoWPAN capability Bits in the Capability Indication
	Option . . . . . . . . . . . . . . . . . . . . . . . . . 14		Option . . . . . . . . . . . . . . . . . . . . . . . . . 15
	7. Backward Compatibility . . . . . . . . . . . . . . . . . . . 14		7. Backward Compatibility . . . . . . . . . . . . . . . . . . . 16
	7.1. Discovering the capabilities of an ND peer . . . . . . . 14		7.1. Discovering the capabilities of an ND peer . . . . . . . 16
	7.1.1. Using the E Flag in the CIO . . . . . . . . . . . . . 14		7.1.1. Using the E Flag in the CIO . . . . . . . . . . . . . 16
	7.1.2. Using the T Flag in the EARO . . . . . . . . . . . . 15		7.1.2. Using the T Flag in the EARO . . . . . . . . . . . . 17
	7.2. Legacy 6LoWPAN Node . . . . . . . . . . . . . . . . . . . 15		7.2. Legacy 6LoWPAN Node . . . . . . . . . . . . . . . . . . . 17
	7.3. Legacy 6LoWPAN Router . . . . . . . . . . . . . . . . . . 16		7.3. Legacy 6LoWPAN Router . . . . . . . . . . . . . . . . . . 17
	7.4. Legacy 6LoWPAN Border Router . . . . . . . . . . . . . . 16		7.4. Legacy 6LoWPAN Border Router . . . . . . . . . . . . . . 18
	8. Security Considerations . . . . . . . . . . . . . . . . . . . 16		8. Security Considerations . . . . . . . . . . . . . . . . . . . 18
	9. Privacy Considerations . . . . . . . . . . . . . . . . . . . 18		9. Privacy Considerations . . . . . . . . . . . . . . . . . . . 20
	10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18		10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
	11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 20		11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 21
	12. References . . . . . . . . . . . . . . . . . . . . . . . . . 20		12. References . . . . . . . . . . . . . . . . . . . . . . . . . 22
	12.1. Normative References . . . . . . . . . . . . . . . . . . 20		12.1. Normative References . . . . . . . . . . . . . . . . . . 22
	12.2. Informative References . . . . . . . . . . . . . . . . . 21		12.2. Informative References . . . . . . . . . . . . . . . . . 23
	12.3. External Informative References . . . . . . . . . . . . 23		12.3. External Informative References . . . . . . . . . . . . 26
	Appendix A. Applicability and Requirements Served . . . . . . . 24		Appendix A. Applicability and Requirements Served . . . . . . . 26
	Appendix B. Requirements . . . . . . . . . . . . . . . . . . . . 24		Appendix B. Requirements . . . . . . . . . . . . . . . . . . . . 27
	B.1. Requirements Related to Mobility . . . . . . . . . . . . 25		B.1. Requirements Related to Mobility . . . . . . . . . . . . 27
	B.2. Requirements Related to Routing Protocols . . . . . . . . 25		B.2. Requirements Related to Routing Protocols . . . . . . . . 27
	B.3. Requirements Related to the Variety of Low-Power Link		B.3. Requirements Related to the Variety of Low-Power Link
	types . . . . . . . . . . . . . . . . . . . . . . . . . . 26		types . . . . . . . . . . . . . . . . . . . . . . . . . . 28
	B.4. Requirements Related to Proxy Operations . . . . . . . . 27		B.4. Requirements Related to Proxy Operations . . . . . . . . 29
	B.5. Requirements Related to Security . . . . . . . . . . . . 27		B.5. Requirements Related to Security . . . . . . . . . . . . 29
	B.6. Requirements Related to Scalability . . . . . . . . . . . 28		B.6. Requirements Related to Scalability . . . . . . . . . . . 31
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 29		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 31
	1. Introduction		1. Introduction
	The scope of this draft is an IPv6 Low Power Networks including star		The scope of this draft is an IPv6 Low Power Networks including star
	and mesh topologies. This specification modifies and extends the		and mesh topologies. This specification modifies and extends the
	behavior and protocol elements of RFC 6775 "Neighbor Discovery		behavior and protocol elements of RFC 6775 "Neighbor Discovery
	Optimization for IPv6 over Low-Power Wireless Personal Area Networks		Optimization for IPv6 over Low-Power Wireless Personal Area Networks
	(6LoWPANs)" [RFC6775] to enable additional capabilities such as:		(6LoWPANs)" [RFC6775] to enable additional capabilities such as:
	* Support the indication of mobility vs retry (T-bit)		* Support the indication of mobility vs retry (T-bit)
	skipping to change at page 6, line 50 ¶		skipping to change at page 6, line 50 ¶
	each re-registration. The TID is used to detect the freshness of the		each re-registration. The TID is used to detect the freshness of the
	registration request and useful to detect one single registration by		registration request and useful to detect one single registration by
	multiple 6LOWPAN border routers supporting the same large 6LOWPAN, as		multiple 6LOWPAN border routers supporting the same large 6LOWPAN, as
	is the case for backbone routers (BBR).		is the case for backbone routers (BBR).
	For example, when a Registered Node is registered with multiple BBRs		For example, when a Registered Node is registered with multiple BBRs
	in parallel, it is expected that the same TID is used, to enable the		in parallel, it is expected that the same TID is used, to enable the
	6BBRs to correlate the registrations as being a single one, and		6BBRs to correlate the registrations as being a single one, and
	differentiate that situation from a movement.		differentiate that situation from a movement.
	Thus TID could be tracked to follow the sequence of mobility of a		Thus the TID could be tracked to follow the sequence of mobility of a
	node. The details protocols of mobility verification by the border		node. The details protocols of mobility verification by the border
	routers is not part of this specification.		routers is not part of this specification.
			4.2.1. Comparing TID values
			The TID is a sequence counter and by design, its operation is the
			exact match of the path sequence specified in RPL, the IPv6 Routing
			Protocol for Low-Power and Lossy Networks [RFC6550] specification.
			In order to keep this document self-contained and yet compatible, the
			text below is an exact copy from section 7.2. "Sequence Counter
			Operation" of [RFC6550]. A TID is deemed to be fresher than another
			when its value is greater per the operations detailed in this
			section.
			The TID range is subdivided in a 'lollipop' fashion ([Perlman83]),
			where the values from 128 and greater are used as a linear sequence
			to indicate a restart and bootstrap the counter, and the values less
			than or equal to 127 used as a circular sequence number space of size
			128 as in [RFC1982]. Consideration is given to the mode of operation
			when transitioning from the linear region to the circular region.
			Finally, when operating in the circular region, if sequence numbers
			are detected to be too far apart then they are not comparable, as
			detailed below.
			A window of comparison, SEQUENCE_WINDOW = 16, is configured based on
			a value of 2^N, where N is defined to be 4 in this specification.
			For a given sequence counter,
			1. The sequence counter SHOULD be initialized to an implementation
			defined value which is 128 or greater prior to use. A
			recommended value is 240 (256 - SEQUENCE_WINDOW).
			2. When a sequence counter increment would cause the sequence
			counter to increment beyond its maximum value, the sequence
			counter MUST wrap back to zero. When incrementing a sequence
			counter greater than or equal to 128, the maximum value is 255.
			When incrementing a sequence counter less than 128, the maximum
			value is 127.
			3. When comparing two sequence counters, the following rules MUST be
			applied:
			1. When a first sequence counter A is in the interval [128..255]
			and a second sequence counter B is in [0..127]:
			1. If (256 + B - A) is less than or equal to
			SEQUENCE_WINDOW, then B is greater than A, A is less than
			B, and the two are not equal.
			2. If (256 + B - A) is greater than SEQUENCE_WINDOW, then A
			is greater than B, B is less than A, and the two are not
			equal.
			For example, if A is 240, and B is 5, then (256 + 5 - 240) is
			21. 21 is greater than SEQUENCE_WINDOW (16), thus 240 is
			greater than 5. As another example, if A is 250 and B is 5,
			then (256 + 5 - 250) is 11. 11 is less than SEQUENCE_WINDOW
			(16), thus 250 is less than 5.
			2. In the case where both sequence counters to be compared are
			less than or equal to 127, and in the case where both
			sequence counters to be compared are greater than or equal to
			128:
			1. If the absolute magnitude of difference between the two
			sequence counters is less than or equal to
			SEQUENCE_WINDOW, then a comparison as described in
			[RFC1982] is used to determine the relationships greater
			than, less than, and equal.
			2. If the absolute magnitude of difference of the two
			sequence counters is greater than SEQUENCE_WINDOW, then a
			desynchronization has occurred and the two sequence
			numbers are not comparable.
			4. If two sequence numbers are determined to be not comparable, i.e.
			the results of the comparison are not defined, then a node should
			consider the comparison as if it has evaluated in such a way so
			as to give precedence to the sequence number that has most
			recently been observed to increment. Failing this, the node
			should consider the comparison as if it has evaluated in such a
			way so as to minimize the resulting changes to its own state.
	4.3. Owner Unique ID		4.3. Owner Unique ID
	The Owner Unique ID (OUID) enables to differentiate a real duplicate		The Owner Unique ID (OUID) enables to differentiate a real duplicate
	address registration from a double registration or a movement. An ND		address registration from a double registration or a movement. An ND
	message from the 6BBR over the Backbone that is proxied on behalf of		message from the 6BBR over the Backbone that is proxied on behalf of
	a Registered Node must carry the most recent EARO option seen for		a Registered Node must carry the most recent EARO option seen for
	that node. A NS/NA with an EARO and a NS/NA without a EARO thus		that node. A NS/NA with an EARO and a NS/NA without a EARO thus
	represent different nodes and if they relate to a same target then		represent different nodes and if they relate to a same target then
	they reflect an address duplication. The Owner Unique ID can be as		they reflect an address duplication. The Owner Unique ID can be as
	simple as a EUI-64 burn-in address, if duplicate EUI-64 addresses are		simple as a EUI-64 burn-in address, if duplicate EUI-64 addresses are
	skipping to change at page 8, line 40 ¶		skipping to change at page 10, line 26 ¶
	An exchange between two nodes using Link-Local addresses implies that		An exchange between two nodes using Link-Local addresses implies that
	they are reachable over one hop and that at least one of the 2 nodes		they are reachable over one hop and that at least one of the 2 nodes
	acts as a 6LR. A node MUST register a Link-Local address to a 6LR in		acts as a 6LR. A node MUST register a Link-Local address to a 6LR in
	order to obtain reachability from that 6LR beyond the current		order to obtain reachability from that 6LR beyond the current
	exchange, and in particular to use the Link-Local address as source		exchange, and in particular to use the Link-Local address as source
	address to register other addresses, e.g. global addresses.		address to register other addresses, e.g. global addresses.
	If there is no collision with an address previously registered to		If there is no collision with an address previously registered to
	this 6LR by another 6LN, then, from the standpoint of this 6LR, this		this 6LR by another 6LN, then, from the standpoint of this 6LR, this
	Link-Local address is unique and the registration is acceptable.		Link-Local address is unique and the registration is acceptable.
	Conversely, it may possibly happen that two different 6LRs expose a		Conversely, it may possibly happen that two different 6LRs expose the
	same Link-Local address but different link-layer addresses. In that		same Link-Local address but different link-layer addresses. In that
	case, a 6LN may only interact with one of the 6LR so as to avoid		case, a 6LN may only interact with one of the 6LR so as to avoid
	confusion in the 6LN neighbor cache.		confusion in the 6LN neighbor cache.
	The DAD process between the 6LR and a 6LoWPAN Border Router (6LBR),		The DAD process between the 6LR and a 6LoWPAN Border Router (6LBR),
	which is based on a Duplicate Address Request (DAR) / Duplicate		which is based on a Duplicate Address Request (DAR) / Duplicate
	Address Confirmation (DAC) exchange as described in RFC 6775		Address Confirmation (DAC) exchange as described in RFC 6775
	[RFC6775], does not need to take place for Link-Local addresses.		[RFC6775], does not need to take place for Link-Local addresses.
	It is desired that a 6LR does not need to modify its state associated		It is desired that a 6LR does not need to modify its state associated
	skipping to change at page 10, line 21 ¶		skipping to change at page 12, line 8 ¶
	messages for the Registered Address. In order to refresh the		messages for the Registered Address. In order to refresh the
	registration state in the 6LBR, these registrations MUST be reported		registration state in the 6LBR, these registrations MUST be reported
	to the 6LBR.		to the 6LBR.
	A node that ceases to use an address SHOULD attempt to deregister		A node that ceases to use an address SHOULD attempt to deregister
	that address from all the 6LRs to which it has registered the		that address from all the 6LRs to which it has registered the
	address, which is achieved using an NS(EARO) message with a		address, which is achieved using an NS(EARO) message with a
	Registration Lifetime of 0.		Registration Lifetime of 0.
	A node that moves away from a particular 6LR SHOULD attempt to		A node that moves away from a particular 6LR SHOULD attempt to
	deregister all of its addresses registered to that 6LR.		deregister all of its addresses registered to that 6LR and register
			to a new 6LR with an incremented TID.
	Upon receiving a NS(EARO) message with a Registration Lifetime of 0		Upon receiving a NS(EARO) message with a Registration Lifetime of 0
	and determining that this EARO is the freshest for a given NCE (see		and determining that this EARO is the freshest for a given NCE (see
	Section 4.2), a 6LR cleans up its NCE. If the address was registered		Section 4.2), a 6LR cleans up its NCE. If the address was registered
	to the 6LBR, then the 6LR MUST report to the 6LBR, through a DAR/DAC		to the 6LBR, then the 6LR MUST report to the 6LBR, through a DAR/DAC
	exchange with the 6LBR, or an alternate protocol, indicating the null		exchange with the 6LBR, or an alternate protocol, indicating the null
	Registration Lifetime and the latest TID that this 6LR is aware of.		Registration Lifetime and the latest TID that this 6LR is aware of.
	Upon the DAR message, the 6LBR evaluates if this is the freshest EARO		Upon the DAR message, the 6LBR evaluates if this is the freshest EARO
	it has received for that particular registry entry. If it is, then		it has received for that particular registry entry. If it is, then
	the entry is scheduled to be removed, and the DAR is answered with a		the entry is scheduled to be removed, and the DAR is answered with a
	DAC message bearing a Status of 0 "Success". If it is not the		DAC message bearing a Status of 0 "Success". If it is not the
	freshest, then a Status 2 "Moved" is returned instead, and the		freshest, then a Status 2 "Moved" is returned instead, and the
	existing entry is conserved. The 6LBR SHOULD conserve the address in		existing entry is conserved.
	a DELAY state for a configurable period of time, so as to protect a
	mobile node that deregistered from one 6LR and did not register yet		Upon timing out a registration, a 6LR removes silently its binding
	to a new one.		cache entry, and a 6LBR schedules its entry to be removed.
			When an address is scheduled to be removed, the 6LBR SHOULD conserve
			its entry in a DELAY state for a configurable period of time, so as
			to protect a mobile node that deregistered from one 6LR and did not
			register yet to a new one, or the new registration did not reach yet
			the 6LBR due to propagation delays in the network. Once the DELAY
			time is passed, the 6LBR removes silently its entry.
	5. Detecting Enhanced ARO Capability Support		5. Detecting Enhanced ARO Capability Support
	The nodes and routers in a network may be mixed and if a node wants		The nodes and routers in a network may be mixed and if a node wants
	to use EARO feature for address registration, it has to find a router		to use EARO feature for address registration, it has to find a router
	which supports it. Thus all implementations with EARO option MUST		which supports it. Thus all implementations with EARO option MUST
	provide the capability detection method using 6CIO option to support		provide the capability detection method using 6CIO option to support
	both types of registrations (ARO and EARO) as described in later		both types of registrations (ARO and EARO) as described in later
	sections. Moreover, any new implementation of 6LOWPAN is also		sections. Moreover, any new implementation of 6LOWPAN is also
	RECOMMENDED to support 6LoWPAN Capability Indication option(6CIO)in		RECOMMENDED to support 6LoWPAN Capability Indication option(6CIO)in
	skipping to change at page 11, line 32 ¶		skipping to change at page 13, line 26 ¶
	6.1. The Enhanced Address Registration Option (EARO)		6.1. The Enhanced Address Registration Option (EARO)
	The Enhanced Address Registration Option (EARO) is intended to be		The Enhanced Address Registration Option (EARO) is intended to be
	used as a replacement to the ARO option within Neighbor Discovery NS		used as a replacement to the ARO option within Neighbor Discovery NS
	and NA messages between a LLN node and its 6LoWPAN Router (6LR), as		and NA messages between a LLN node and its 6LoWPAN Router (6LR), as
	well as in Duplicate Address Request (DAR) and the Duplicate Address		well as in Duplicate Address Request (DAR) and the Duplicate Address
	Confirmation (DAC) messages between 6LRs and 6LBRs in LLNs meshes		Confirmation (DAC) messages between 6LRs and 6LBRs in LLNs meshes
	such as 6TiSCH networks.		such as 6TiSCH networks.
	An NS message with an EARO option is a registration if and only if it		An NS message with an EARO option is a registration if and only if it
	also carries an SLLAO option. The AERO option also used in NS and NA		also carries an SLLAO option. The EARO option also used in NS and NA
	messages between Backbone Routers over the Backbone link to sort out		messages between Backbone Routers over the Backbone link to sort out
	the distributed registration state, and in that case, it does not		the distributed registration state, and in that case, it does not
	carry the SLLAO option and is not confused with a registration.		carry the SLLAO option and is not confused with a registration.
	The EARO extends the ARO and is recognized by the "T" flag set.
	When using the EARO option, the address being registered is found in		When using the EARO option, the address being registered is found in
	the Target Address field of the NS and NA messages. This differs		the Target Address field of the NS and NA messages. This differs
	from 6LoWPAN ND RFC 6775 [RFC6775] which specifies that the address		from 6LoWPAN ND RFC 6775 [RFC6775] which specifies that the address
	being registered is the source of the NS.		being registered is the source of the NS.
	The format of the EARO option is as follows:		The EARO extends the ARO and is recognized by the "T" flag set. The
			format of the EARO option is as follows:
	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 = 2 | Status | Reserved |		| Type | Length = 2 | Status | Reserved |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Reserved |T| TID | Registration Lifetime |		| Reserved |T| TID | Registration Lifetime |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| |		| |
	+ Owner Unique ID (EUI-64 or equivalent) +		+ Owner Unique ID (EUI-64 or equivalent) +
	| |		| |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Figure 1: EARO		Figure 1: EARO
	Option Fields		Option Fields
	Type: 33		Type: 33
	Length: 8-bit unsigned integer.
	Status: 8-bit unsigned integer. Indicates the status of a
	registration in the NA response. MUST be set to 0 in NS messages.
	See Table 1 below.
	Reserved: This field is unused. It MUST be initialized to zero by
	the sender and MUST be ignored by the receiver.
	T: One bit flag. Set if the next octet is a used as a TID.
	TID: 1-byte integer; a transaction id that is maintained by the node
	and incremented with each transaction. it is recommended that the
	node maintains the TID in a persistent storage.
	Registration Lifetime: 16-bit integer; expressed in minutes. 0		Length: 8-bit unsigned integer.
	means that the registration has ended and the associated state
	should be removed.
	Owner Unique Identifier (OUI): A globally unique identifier for the		Status: 8-bit unsigned integer. Indicates the status of a
	node associated. This can be the EUI-64 derived IID of an		registration in the NA response. MUST be set to 0 in
	interface, or some provable ID obtained cryptographically.		NS messages. See Table 1 below.
	+-------+-----------------------------------------------------------+		+-------+-----------------------------------------------------------+
	| Value | Description |		| Value | Description |
	+-------+-----------------------------------------------------------+		+-------+-----------------------------------------------------------+
	| 0..2 | See RFC 6775 [RFC6775]. Note that a Status of 1 |		| 0..2 | See RFC 6775 [RFC6775]. Note that a Status of 1 |
	| | "Duplicate Address" applies to the Registered Address. If |		| | "Duplicate Address" applies to the Registered Address. If |
	| | the Source Address conflicts with an existing |		| | the Source Address conflicts with an existing |
	| | registration, "Duplicate Source Address" should be used. |		| | registration, "Duplicate Source Address" should be used. |
	| | |		| | |
	| 3 | Moved: The registration fails because it is not the |		| 3 | Moved: The registration fails because it is not the |
	skipping to change at page 13, line 47 ¶		skipping to change at page 15, line 16 ¶
	| | |		| | |
	| 9 | 6LBR Registry saturated: A new registration cannot be |		| 9 | 6LBR Registry saturated: A new registration cannot be |
	| | accepted because the 6LBR Registry is saturated. |		| | accepted because the 6LBR Registry is saturated. |
	| | |		| | |
	| 10 | Incorrect proof: The proof of ownership of the registered |		| 10 | Incorrect proof: The proof of ownership of the registered |
	| | address is not correct. |		| | address is not correct. |
	+-------+-----------------------------------------------------------+		+-------+-----------------------------------------------------------+
	Table 1: EARO Status		Table 1: EARO Status
			Reserved: This field is unused. It MUST be initialized to zero
			by the sender and MUST be ignored by the receiver.
			T: One bit flag. Set if the next octet is a used as a
			TID.
			TID: 1-byte integer; a transaction id that is maintained
			by the node and incremented with each transaction.
			it is recommended that the node maintains the TID in
			a persistent storage.
			Registration Lifetime: 16-bit integer; expressed in minutes. 0
			means that the registration has ended and the
			associated state should be removed.
			Owner Unique Identifier (OUI): A globally unique identifier for the
			node associated. This can be the EUI-64 derived IID
			of an interface, or some provable ID obtained
			cryptographically.
	Note: the code "6LBR Registry saturated" is used by 6LBRs instead of		Note: the code "6LBR Registry saturated" is used by 6LBRs instead of
	Status 2 when responding to a DAR/DAC exchange and passed on to the		Status 2 when responding to a DAR/DAC exchange and passed on to the
	Registering Node by the 6LR. There is no point for the node to retry		Registering Node by the 6LR. There is no point for the node to retry
	this registration immediately via another 6LR, since the problem is		this registration immediately via another 6LR, since the problem is
	global to the network. The node may either abandon that address,		global to the network. The node may either abandon that address,
	deregister other addresses first to make room, or keep the address in		deregister other addresses first to make room, or keep the address in
	TENTATIVE state and retry later.		TENTATIVE state and retry later.
	6.2. New 6LoWPAN capability Bits in the Capability Indication Option		6.2. New 6LoWPAN capability Bits in the Capability Indication Option
	skipping to change at page 16, line 13 ¶		skipping to change at page 17, line 50 ¶
	[RFC6775] specification, and manage the binding cache accordingly.		[RFC6775] specification, and manage the binding cache accordingly.
	The main difference with RFC 6775 is that DAR/DAC exchange for DAD		The main difference with RFC 6775 is that DAR/DAC exchange for DAD
	may be avoided for Link-Local addresses. Additionally, the 6LR		may be avoided for Link-Local addresses. Additionally, the 6LR
	SHOULD use an EARO in the reply, and may use any of the Status codes		SHOULD use an EARO in the reply, and may use any of the Status codes
	defined in this specification.		defined in this specification.
	7.3. Legacy 6LoWPAN Router		7.3. Legacy 6LoWPAN Router
	The first registration by a an updated 6LN is for a Link-Local		The first registration by a an updated 6LN is for a Link-Local
	address, using that Link-Local address as source. A legacy 6LN will		address, using that Link-Local address as source. A legacy 6LR will
	not makes a difference and accept -or reject- that registration as if		not make a difference and accept -or reject- that registration as if
	the 6LN was a legacy node.		the 6LN was a legacy node.
	An updated 6LN will always use an EARO option in the registration NS		An updated 6LN will always use an EARO option in the registration NS
	message, whereas a legacy 6LN will always areply with an ARO option		message, whereas a legacy 6LR will always reply with an ARO option in
	in the NA message. So from that first registration, the updated 6LN		the NA message. So from that first registration, the updated 6LN can
	can figure whether the 6LR supports this specification or not.		figure whether the 6LR supports this specification or not.
	When facing a legacy 6LR, an updated 6LN may attempt to find an		When facing a legacy 6LR, an updated 6LN may attempt to find an
	alternate 6LR that is updated. In order to be backward compatible,		alternate 6LR that is updated. In order to be backward compatible,
	based on the discovery that a 6LR is legacy, the 6LN needs to		based on the discovery that a 6LR is legacy, the 6LN needs to
	fallback to legacy behavior and source the packet with the Registered		fallback to legacy behavior and source the packet with the Registered
	Address.		Address.
	The main difference is that the updated 6LN SHOULD use an EARO in the		The main difference is that the updated 6LN SHOULD use an EARO in the
	request regardless of the type of 6LN, legacy or updated		request regardless of the type of 6LR, legacy or updated
	7.4. Legacy 6LoWPAN Border Router		7.4. Legacy 6LoWPAN Border Router
	With this specification, the DAR/DAC transports an EARO option as		With this specification, the DAR/DAC transports an EARO option as
	opposed to an ARO option. As described for the NS/NA exchange,		opposed to an ARO option. As described for the NS/NA exchange, 6LBR
	devices that support this specification always use an EARO option and		devices that support this specification always use an EARO option and
	all the associated behavior.		all the associated behavior. A legacy 6LBR will accept and process
			an EARO option as if it was an ARO option, so the legacy support of
			DAD will function. But considering that there are a lot fewer 6LBR
			than 6LR, the expectation is that they are upgraded as soon as
			devices that implement this specification are deployed.
	8. Security Considerations		8. Security Considerations
	This specification extends RFC 6775 [RFC6775], and the security		This specification extends RFC 6775 [RFC6775], and the security
	section of that draft also applies to this as well. In particular,		section of that draft also applies to this as well. In particular,
	it is expected that the link layer is sufficiently protected to		it is expected that the link layer is sufficiently protected to
	prevent a rogue access, either by means of physical or IP security on		prevent a rogue access, either by means of physical or IP security on
	the Backbone Link and link layer cryptography on the LLN. This		the Backbone Link and link layer cryptography on the LLN. This
	specification also expects that the LLN MAC provides secure unicast		specification also expects that the LLN MAC provides secure unicast
	to/from the Backbone Router and secure Broadcast from the Backbone		to/from the Backbone Router and secure Broadcast from the Backbone
	skipping to change at page 18, line 38 ¶		skipping to change at page 20, line 32 ¶
	specifications involving 6LOWPAN Neighbor Discovery should consult		specifications involving 6LOWPAN Neighbor Discovery should consult
	"Recommendation on Stable IPv6 Interface Identifiers" [RFC8064] for		"Recommendation on Stable IPv6 Interface Identifiers" [RFC8064] for
	default interface identifaction.		default interface identifaction.
	10. IANA Considerations		10. IANA Considerations
	IANA is requested to create a new subregistry for "ARO Flags" under		IANA is requested to create a new subregistry for "ARO Flags" under
	the "Internet Control Message Protocol version 6 (ICMPv6)		the "Internet Control Message Protocol version 6 (ICMPv6)
	Parameters". This specification defines 8 positions, bit 0 to bit 7,		Parameters". This specification defines 8 positions, bit 0 to bit 7,
	and assigns bit 7 for the "T" flag in Section 6.1. The policy is		and assigns bit 7 for the "T" flag in Section 6.1. The policy is
	"IETF Review" or "IESG Approval" [RFC5226]. The initial content of		"IETF Review" or "IESG Approval" [RFC8126]. The initial content of
	the registry is as shown in Table 2.		the registry is as shown in Table 2.
	New subregistry for ARO Flags under the "Internet Control Message		New subregistry for ARO Flags under the "Internet Control Message
	Protocol version 6 (ICMPv6) Parameters"		Protocol version 6 (ICMPv6) Parameters"
	+------------+--------------+-----------+		+------------+--------------+-----------+
	| ARO Status | Description | Document |		| ARO Status | Description | Document |
	+------------+--------------+-----------+		+------------+--------------+-----------+
	| 0..6 | Unassigned | |		| 0..6 | Unassigned | |
	| | | |		| | | |
	skipping to change at page 20, line 8 ¶		skipping to change at page 21, line 50 ¶
	| 13 | 6BBR capable (P bit) | RFC This |		| 13 | 6BBR capable (P bit) | RFC This |
	| | | |		| | | |
	| 14 | EARO support (E bit) | RFC This |		| 14 | EARO support (E bit) | RFC This |
	+----------------+----------------------+-----------+		+----------------+----------------------+-----------+
	Table 4: New 6LoWPAN capability Bits		Table 4: New 6LoWPAN capability Bits
	11. Acknowledgments		11. Acknowledgments
	Kudos to Eric Levy-Abegnoli who designed the First Hop Security		Kudos to Eric Levy-Abegnoli who designed the First Hop Security
	infrastructure at Cisco.		infrastructure at Cisco, upon which the first backbone router wsa
			implemented; many thanks to Sedat Gormus, Rahul Jadhav, Charlie
			Perkins for their various contributions and reviews. Also many
			thanks to Thomas Watteyne for his early implementation of a 6LN that
			was instrumental to test the 6LR, 6LBR and Backbone Router.
	12. References		12. References
	12.1. Normative References		12.1. Normative References
	[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,
	<http://www.rfc-editor.org/info/rfc2119>.		<http://www.rfc-editor.org/info/rfc2119>.
	skipping to change at page 20, line 33 ¶		skipping to change at page 22, line 30 ¶
	[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,
	<http://www.rfc-editor.org/info/rfc4861>.		<http://www.rfc-editor.org/info/rfc4861>.
	[RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless		[RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
	Address Autoconfiguration", RFC 4862,		Address Autoconfiguration", RFC 4862,
	DOI 10.17487/RFC4862, September 2007,		DOI 10.17487/RFC4862, September 2007,
	<http://www.rfc-editor.org/info/rfc4862>.		<http://www.rfc-editor.org/info/rfc4862>.
	[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
	IANA Considerations Section in RFCs", RFC 5226,
	DOI 10.17487/RFC5226, May 2008,
	<http://www.rfc-editor.org/info/rfc5226>.
	[RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6		[RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6
	Datagrams over IEEE 802.15.4-Based Networks", RFC 6282,		Datagrams over IEEE 802.15.4-Based Networks", RFC 6282,
	DOI 10.17487/RFC6282, September 2011,		DOI 10.17487/RFC6282, September 2011,
	<http://www.rfc-editor.org/info/rfc6282>.		<http://www.rfc-editor.org/info/rfc6282>.
	[RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C.		[RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C.
	Bormann, "Neighbor Discovery Optimization for IPv6 over		Bormann, "Neighbor Discovery Optimization for IPv6 over
	Low-Power Wireless Personal Area Networks (6LoWPANs)",		Low-Power Wireless Personal Area Networks (6LoWPANs)",
	RFC 6775, DOI 10.17487/RFC6775, November 2012,		RFC 6775, DOI 10.17487/RFC6775, November 2012,
	<http://www.rfc-editor.org/info/rfc6775>.		<http://www.rfc-editor.org/info/rfc6775>.
	[RFC7400] Bormann, C., "6LoWPAN-GHC: Generic Header Compression for		[RFC7400] Bormann, C., "6LoWPAN-GHC: Generic Header Compression for
	IPv6 over Low-Power Wireless Personal Area Networks		IPv6 over Low-Power Wireless Personal Area Networks
	(6LoWPANs)", RFC 7400, DOI 10.17487/RFC7400, November		(6LoWPANs)", RFC 7400, DOI 10.17487/RFC7400, November
	2014, <http://www.rfc-editor.org/info/rfc7400>.		2014, <http://www.rfc-editor.org/info/rfc7400>.
			[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
			Writing an IANA Considerations Section in RFCs", BCP 26,
			RFC 8126, DOI 10.17487/RFC8126, June 2017,
			<http://www.rfc-editor.org/info/rfc8126>.
	12.2. Informative References		12.2. Informative References
	[I-D.chakrabarti-nordmark-6man-efficient-nd]		[I-D.chakrabarti-nordmark-6man-efficient-nd]
	Chakrabarti, S., Nordmark, E., Thubert, P., and M.		Chakrabarti, S., Nordmark, E., Thubert, P., and M.
	Wasserman, "IPv6 Neighbor Discovery Optimizations for		Wasserman, "IPv6 Neighbor Discovery Optimizations for
	Wired and Wireless Networks", draft-chakrabarti-nordmark-		Wired and Wireless Networks", draft-chakrabarti-nordmark-
	6man-efficient-nd-07 (work in progress), February 2015.		6man-efficient-nd-07 (work in progress), February 2015.
	[I-D.delcarpio-6lo-wlanah]		[I-D.delcarpio-6lo-wlanah]
	Vega, L., Robles, I., and R. Morabito, "IPv6 over		Vega, L., Robles, I., and R. Morabito, "IPv6 over
	skipping to change at page 21, line 26 ¶		skipping to change at page 23, line 26 ¶
	progress), October 2015.		progress), October 2015.
	[I-D.ietf-6lo-ap-nd]		[I-D.ietf-6lo-ap-nd]
	Sarikaya, B., Thubert, P., and M. Sethi, "Address		Sarikaya, B., Thubert, P., and M. Sethi, "Address
	Protected Neighbor Discovery for Low-power and Lossy		Protected Neighbor Discovery for Low-power and Lossy
	Networks", draft-ietf-6lo-ap-nd-02 (work in progress), May		Networks", draft-ietf-6lo-ap-nd-02 (work in progress), May
	2017.		2017.
	[I-D.ietf-6lo-backbone-router]		[I-D.ietf-6lo-backbone-router]
	Thubert, P., "IPv6 Backbone Router", draft-ietf-6lo-		Thubert, P., "IPv6 Backbone Router", draft-ietf-6lo-
	backbone-router-03 (work in progress), January 2017.		backbone-router-04 (work in progress), July 2017.
	[I-D.ietf-6lo-nfc]		[I-D.ietf-6lo-nfc]
	Choi, Y., Hong, Y., Youn, J., Kim, D., and J. Choi,		Choi, Y., Hong, Y., Youn, J., Kim, D., and J. Choi,
	"Transmission of IPv6 Packets over Near Field		"Transmission of IPv6 Packets over Near Field
	Communication", draft-ietf-6lo-nfc-07 (work in progress),		Communication", draft-ietf-6lo-nfc-07 (work in progress),
	June 2017.		June 2017.
	[I-D.ietf-6tisch-architecture]		[I-D.ietf-6tisch-architecture]
	Thubert, P., "An Architecture for IPv6 over the TSCH mode		Thubert, P., "An Architecture for IPv6 over the TSCH mode
	of IEEE 802.15.4", draft-ietf-6tisch-architecture-11 (work		of IEEE 802.15.4", draft-ietf-6tisch-architecture-11 (work
	skipping to change at page 22, line 11 ¶		skipping to change at page 24, line 11 ¶
	Thaler, D. and C. Huitema, "Multi-link Subnet Support in		Thaler, D. and C. Huitema, "Multi-link Subnet Support in
	IPv6", draft-ietf-ipv6-multilink-subnets-00 (work in		IPv6", draft-ietf-ipv6-multilink-subnets-00 (work in
	progress), July 2002.		progress), July 2002.
	[I-D.popa-6lo-6loplc-ipv6-over-ieee19012-networks]		[I-D.popa-6lo-6loplc-ipv6-over-ieee19012-networks]
	Popa, D. and J. Hui, "6LoPLC: Transmission of IPv6 Packets		Popa, D. and J. Hui, "6LoPLC: Transmission of IPv6 Packets
	over IEEE 1901.2 Narrowband Powerline Communication		over IEEE 1901.2 Narrowband Powerline Communication
	Networks", draft-popa-6lo-6loplc-ipv6-over-		Networks", draft-popa-6lo-6loplc-ipv6-over-
	ieee19012-networks-00 (work in progress), March 2014.		ieee19012-networks-00 (work in progress), March 2014.
			[RFC1982] Elz, R. and R. Bush, "Serial Number Arithmetic", RFC 1982,
			DOI 10.17487/RFC1982, August 1996,
			<http://www.rfc-editor.org/info/rfc1982>.
	[RFC3610] Whiting, D., Housley, R., and N. Ferguson, "Counter with		[RFC3610] Whiting, D., Housley, R., and N. Ferguson, "Counter with
	CBC-MAC (CCM)", RFC 3610, DOI 10.17487/RFC3610, September		CBC-MAC (CCM)", RFC 3610, DOI 10.17487/RFC3610, September
	2003, <http://www.rfc-editor.org/info/rfc3610>.		2003, <http://www.rfc-editor.org/info/rfc3610>.
	[RFC3810] Vida, R., Ed. and L. Costa, Ed., "Multicast Listener		[RFC3810] Vida, R., Ed. and L. Costa, Ed., "Multicast Listener
	Discovery Version 2 (MLDv2) for IPv6", RFC 3810,		Discovery Version 2 (MLDv2) for IPv6", RFC 3810,
	DOI 10.17487/RFC3810, June 2004,		DOI 10.17487/RFC3810, June 2004,
	<http://www.rfc-editor.org/info/rfc3810>.		<http://www.rfc-editor.org/info/rfc3810>.
	[RFC3971] Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander,		[RFC3971] Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander,
	skipping to change at page 24, line 5 ¶		skipping to change at page 26, line 12 ¶
	Passing (MS/TP) Networks", RFC 8163, DOI 10.17487/RFC8163,		Passing (MS/TP) Networks", RFC 8163, DOI 10.17487/RFC8163,
	May 2017, <http://www.rfc-editor.org/info/rfc8163>.		May 2017, <http://www.rfc-editor.org/info/rfc8163>.
	12.3. External Informative References		12.3. External Informative References
	[IEEEstd802154]		[IEEEstd802154]
	IEEE, "IEEE Standard for Low-Rate Wireless Networks",		IEEE, "IEEE Standard for Low-Rate Wireless Networks",
	IEEE Standard 802.15.4, DOI 10.1109/IEEESTD.2016.7460875,		IEEE Standard 802.15.4, DOI 10.1109/IEEESTD.2016.7460875,
	<http://ieeexplore.ieee.org/document/7460875/>.		<http://ieeexplore.ieee.org/document/7460875/>.
			[Perlman83]
			Perlman, R., "Fault-Tolerant Broadcast of Routing
			Information", North-Holland Computer Networks 7: 395-405,
			1983, <http://www.cs.illinois.edu/~pbg/courses/cs598fa09/
			readings/p83.pdf>.
	Appendix A. Applicability and Requirements Served		Appendix A. Applicability and Requirements Served
	This specification extends 6LoWPAN ND to sequence the registration		This specification extends 6LoWPAN ND to sequence the registration
	and serves the requirements expressed Appendix B.1 by enabling the		and serves the requirements expressed Appendix B.1 by enabling the
	mobility of devices from one LLN to the next based on the		mobility of devices from one LLN to the next based on the
	complementary work in the "IPv6 Backbone Router"		complementary work in the "IPv6 Backbone Router"
	[I-D.ietf-6lo-backbone-router] specification.		[I-D.ietf-6lo-backbone-router] specification.
	In the context of the the TimeSlotted Channel Hopping (TSCH) mode of		In the context of the the TimeSlotted Channel Hopping (TSCH) mode of
	IEEE Std. 802.15.4 [IEEEstd802154], the "6TiSCH architecture"		IEEE Std. 802.15.4 [IEEEstd802154], the "6TiSCH architecture"
End of changes. 30 change blocks.
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