draft-ietf-roll-efficient-npdao-06.txt		draft-ietf-roll-efficient-npdao-07.txt
	ROLL R. Jadhav, Ed.		ROLL R. Jadhav, Ed.
	Internet-Draft Huawei		Internet-Draft Huawei
	Intended status: Standards Track P. Thubert		Intended status: Standards Track P. Thubert
	Expires: March 30, 2019 Cisco		Expires: March 31, 2019 Cisco
	R. Sahoo		R. Sahoo
	Z. Cao		Z. Cao
	Huawei		Huawei
	September 26, 2018		September 27, 2018
	Efficient Route Invalidation		Efficient Route Invalidation
	draft-ietf-roll-efficient-npdao-06		draft-ietf-roll-efficient-npdao-07
	Abstract		Abstract
	This document describes the problems associated with the use of NPDAO		This document describes the problems associated with the use of NPDAO
	messaging in RPL and signaling changes to improve route invalidation		messaging in RPL and signaling changes to improve route invalidation
	efficiency.		efficiency.
	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
	skipping to change at page 1, line 36 ¶		skipping to change at page 1, line 36 ¶
	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 https://datatracker.ietf.org/drafts/current/.		Drafts is at https://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 March 30, 2019.		This Internet-Draft will expire on March 31, 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
	(https://trustee.ietf.org/license-info) in effect on the date of		(https://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
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	described in the Simplified BSD License.		described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
	1.1. Requirements Language and Terminology . . . . . . . . . . 3		1.1. Requirements Language and Terminology . . . . . . . . . . 3
	1.2. Current NPDAO messaging . . . . . . . . . . . . . . . . . 3		1.2. Current NPDAO messaging . . . . . . . . . . . . . . . . . 4
	1.3. Why NPDAO is important? . . . . . . . . . . . . . . . . . 4		1.3. Why NPDAO is important? . . . . . . . . . . . . . . . . . 4
	2. Problems with current NPDAO messaging . . . . . . . . 5		2. Problems with current NPDAO messaging . . . . . . . . 5
	2.1. Lost NPDAO due to link break to the previous parent . . . 5		2.1. Lost NPDAO due to link break to the previous parent . . . 5
	2.2. Invalidate routes to dependent nodes . . . . . . . . . . 5		2.2. Invalidate routes to dependent nodes . . . . . . . . . . 5
	2.3. Possible route downtime caused by async operation of		2.3. Possible route downtime caused by async operation of
	NPDAO and DAO . . . . . . . . . . . . . . . . . . . . . . 5		NPDAO and DAO . . . . . . . . . . . . . . . . . . . . . . 5
	3. Requirements for the NPDAO Optimization . . . . . . . . . . . 5		3. Requirements for the NPDAO Optimization . . . . . . . . . . . 5
	3.1. Req#1: Tolerant to link failures to the previous		3.1. Req#1: Tolerant to link failures to the previous
	parents . . . . . . . . . . . . . . . . . . . . . . . . . 5		parents . . . . . . . . . . . . . . . . . . . . . . . . . 5
	3.2. Req#2: Dependent nodes route invalidation on parent		3.2. Req#2: Dependent nodes route invalidation on parent
	skipping to change at page 2, line 36 ¶		skipping to change at page 2, line 36 ¶
	4.2. Transit Information Option changes . . . . . . . . . . . 7		4.2. Transit Information Option changes . . . . . . . . . . . 7
	4.3. Destination Cleanup Object (DCO) . . . . . . . . . . . . 8		4.3. Destination Cleanup Object (DCO) . . . . . . . . . . . . 8
	4.3.1. Secure DCO . . . . . . . . . . . . . . . . . . . . . 9		4.3.1. Secure DCO . . . . . . . . . . . . . . . . . . . . . 9
	4.3.2. DCO Options . . . . . . . . . . . . . . . . . . . . . 9		4.3.2. DCO Options . . . . . . . . . . . . . . . . . . . . . 9
	4.3.3. Path Sequence number in the DCO . . . . . . . . . . . 9		4.3.3. Path Sequence number in the DCO . . . . . . . . . . . 9
	4.3.4. Destination Cleanup Option Acknowledgement (DCO-ACK) 9		4.3.4. Destination Cleanup Option Acknowledgement (DCO-ACK) 9
	4.3.5. Secure DCO-ACK . . . . . . . . . . . . . . . . . . . 10		4.3.5. Secure DCO-ACK . . . . . . . . . . . . . . . . . . . 10
	4.4. Other considerations . . . . . . . . . . . . . . . . . . 11		4.4. Other considerations . . . . . . . . . . . . . . . . . . 11
	4.4.1. Dependent Nodes invalidation . . . . . . . . . . . . 11		4.4.1. Dependent Nodes invalidation . . . . . . . . . . . . 11
	4.4.2. NPDAO and DCO in the same network . . . . . . . . . . 11		4.4.2. NPDAO and DCO in the same network . . . . . . . . . . 11
			4.4.3. DCO with multiple preferred parents . . . . . . . . . 11
	5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11		5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11
	6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11		6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
	7. Security Considerations . . . . . . . . . . . . . . . . . . . 12		7. Security Considerations . . . . . . . . . . . . . . . . . . . 12
	8. References . . . . . . . . . . . . . . . . . . . . . . . . . 12		8. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
	8.1. Normative References . . . . . . . . . . . . . . . . . . 12		8.1. Normative References . . . . . . . . . . . . . . . . . . 12
	8.2. Informative References . . . . . . . . . . . . . . . . . 12		8.2. Informative References . . . . . . . . . . . . . . . . . 12
	Appendix A. Example DCO Messaging . . . . . . . . . . . . . . . 12		Appendix A. Example DCO Messaging . . . . . . . . . . . . . . . 13
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
	1. Introduction		1. Introduction
	RPL [RFC6550] specifies a proactive distance-vector based routing		RPL [RFC6550] specifies a proactive distance-vector based routing
	scheme. RPL has an optional messaging in the form of DAO messages		scheme. RPL has an optional messaging in the form of DAO
	using which the 6LBR can learn route towards the nodes. In storing		(Destination Advertisement Object) messages using which the 6LBR can
	mode, DAO messages would result in routing entries been created on		learn route towards the nodes. In storing mode, DAO messages would
	all intermediate hops from the node's parent all the way towards the		result in routing entries been created on all intermediate hops from
	6LBR.		the node's parent all the way towards the 6LBR.
	RPL allows use of No-Path DAO (NPDAO) messaging to invalidate a		RPL allows use of No-Path DAO (NPDAO) messaging to invalidate a
	routing path corresponding to the given target, thus releasing		routing path corresponding to the given target, thus releasing
	resources utilized on that path. A NPDAO is a DAO message with route		resources utilized on that path. A NPDAO is a DAO message with route
	lifetime of zero, originates at the target node and always flows		lifetime of zero, originates at the target node and always flows
	upstream towards the 6LBR. This document explains the problems		upstream towards the 6LBR. This document explains the problems
	associated with the current use of NPDAO messaging and also discusses		associated with the current use of NPDAO messaging and also discusses
	the requirements for an optimized route invalidation messaging		the requirements for an optimized route invalidation messaging
	scheme. Further a new pro-active route invalidation message called		scheme. Further a new pro-active route invalidation message called
	as "Destination Cleanup Object (DCO)" is specified which fulfills		as "Destination Cleanup Object (DCO)" is specified which fulfills
	requirements of an optimized route invalidation messaging.		requirements of an optimized route invalidation messaging.
			The document only caters to the RPL's storing mode of operation
			(MOP). The non-storing MOP does not require use of NPDAO for route
			invalidation since routing entries are not maintained on 6LRs.
	1.1. Requirements Language and Terminology		1.1. Requirements Language and Terminology
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this		"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
	document are to be interpreted as described in RFC 2119 [RFC2119].		document are to be interpreted as described in RFC 2119 [RFC2119].
	The document only caters to the RPL's storing mode of operation		DAO: Destination Advertisement Object
	(MOP). The non-storing MOP does not require use of NPDAO for route
	invalidation since routing entries are not maintained on 6LRs.		DIO: DODAG Information Object
	Common Ancestor node: 6LR node which is the first common node on the		Common Ancestor node: 6LR node which is the first common node on the
	old and new path for the child node.		old and new path for the child node.
	NPDAO: No-Path DAO. A DAO message which has target with lifetime 0.		NPDAO: No-Path DAO. A DAO message which has target with lifetime 0.
	DCO: Destination Cleanup Object, A new RPL control message type		DCO: Destination Cleanup Object, A new RPL control message type
	defined by this draft.		defined by this draft.
	Regular DAO: A DAO message with non-zero lifetime.		Regular DAO: A DAO message with non-zero lifetime.
	skipping to change at page 5, line 46 ¶		skipping to change at page 5, line 52 ¶
	to (C). An NPDAO sent from previous route may invalidate the		to (C). An NPDAO sent from previous route may invalidate the
	existing route whereas there is no way to determine whether the new		existing route whereas there is no way to determine whether the new
	DAO has successfully updated the route entries on the new path.		DAO has successfully updated the route entries on the new path.
	3. Requirements for the NPDAO Optimization		3. Requirements for the NPDAO Optimization
	3.1. Req#1: Tolerant to link failures to the previous parents		3.1. Req#1: Tolerant to link failures to the previous parents
	When the switching node sends the NPDAO message to the previous		When the switching node sends the NPDAO message to the previous
	parent, it is normal that the link to the previous parent is prone to		parent, it is normal that the link to the previous parent is prone to
	failure. Therefore, it is required that the NPDAO message must be		failure. Therefore, it is required that the route invalidation does
	tolerant to the link failure. The link referred here represents the		not depend on the previous link which is prone to failure. The
	link between the node and its previous parent (from whom the node is		previous link referred here represents the link between the node and
	now disassociating).		its previous parent (from whom the node is now disassociating).
	3.2. Req#2: Dependent nodes route invalidation on parent switching		3.2. Req#2: Dependent nodes route invalidation on parent switching
	It should be possible to do route invalidation for dependent nodes		It should be possible to do route invalidation for dependent nodes
	rooted at the switching node.		rooted at the switching node.
	3.3. Req#3: Route invalidation should not impact data traffic		3.3. Req#3: Route invalidation should not impact data traffic
	While sending the NPDAO and DAO messages, it is possible that the		While sending the NPDAO and DAO messages, it is possible that the
	NPDAO successfully invalidates the previous path, while the newly		NPDAO successfully invalidates the previous path, while the newly
	skipping to change at page 7, line 19 ¶		skipping to change at page 7, line 19 ¶
	are appended to add message/use-case specific attributes. As an		are appended to add message/use-case specific attributes. As an
	example, a DAO message may be attributed by one or more "RPL Target"		example, a DAO message may be attributed by one or more "RPL Target"
	options which specifies the reachability information for the given		options which specifies the reachability information for the given
	targets. Similarly, a Transit Information option may be associated		targets. Similarly, a Transit Information option may be associated
	with a set of RPL Target options.		with a set of RPL Target options.
	The draft proposes a change in Transit Information option to contain		The draft proposes a change in Transit Information option to contain
	"Invalidate previous route" (I) bit. This I-bit signals the common		"Invalidate previous route" (I) bit. This I-bit signals the common
	ancestor node to generate a DCO on behalf of the target node. The		ancestor node to generate a DCO on behalf of the target node. The
	I-bit is carried in the transit information option which augments the		I-bit is carried in the transit information option which augments the
	reachability information for a given set of RPL Target(s).		reachability information for a given set of RPL Target(s). Transit
			information option should be carried in the DAO message with I-bit
			set in case route invalidation is sought for the correspondig
			target(s).
	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 = 0x06 | Option Length |E|I| Flags | Path Control |		| Type = 0x06 | Option Length |E|I| Flags | Path Control |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Path Sequence | Path Lifetime | |		| Path Sequence | Path Lifetime | |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
	| |		| |
	+ +		+ +
	skipping to change at page 9, line 37 ¶		skipping to change at page 9, line 37 ¶
	The DCO carries a Target option and an associated Transit Information		The DCO carries a Target option and an associated Transit Information
	option with a lifetime of 0x00000000 to indicate a loss of		option with a lifetime of 0x00000000 to indicate a loss of
	reachability to that Target.		reachability to that Target.
	4.3.3. Path Sequence number in the DCO		4.3.3. Path Sequence number in the DCO
	A DCO message may contain a Path Sequence in the transit information		A DCO message may contain a Path Sequence in the transit information
	option to identify the freshness of the DCO message. The Path		option to identify the freshness of the DCO message. The Path
	Sequence in the DCO MUST use the same Path Sequence number present in		Sequence in the DCO MUST use the same Path Sequence number present in
	the regular DAO message when the DCO is generated in response to DAO		the regular DAO message when the DCO is generated in response to DAO
	message.		message. The DAO and DCO path sequence are picked from the same
			sequence number set. Thus if a DCO is received by a 6LR and
			subsequently a DAO is received with old seqeunce number, then the DAO
			should be ignored.
	4.3.4. Destination Cleanup Option Acknowledgement (DCO-ACK)		4.3.4. Destination Cleanup Option Acknowledgement (DCO-ACK)
	The DCO-ACK message may be sent as a unicast packet by a DCO		The DCO-ACK message may be sent as a unicast packet by a DCO
	recipient in response to a unicast DCO message.		recipient in response to a unicast DCO message.
	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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| RPLInstanceID |D| Reserved | DCOSequence | Status |		| RPLInstanceID |D| Reserved | DCOSequence | Status |
	skipping to change at page 11, line 21 ¶		skipping to change at page 11, line 21 ¶
	nodes invalidation. Dependent nodes will generate their respective		nodes invalidation. Dependent nodes will generate their respective
	DAOs to update their paths, and the previous route invalidation for		DAOs to update their paths, and the previous route invalidation for
	those nodes should work in the similar manner described for switching		those nodes should work in the similar manner described for switching
	node. The dependent node may set the I-bit in the transit		node. The dependent node may set the I-bit in the transit
	information option as part of regular DAO so as to request		information option as part of regular DAO so as to request
	invalidation of previous route from the common ancestor node.		invalidation of previous route from the common ancestor node.
	4.4.2. NPDAO and DCO in the same network		4.4.2. NPDAO and DCO in the same network
	Even with the changed semantics, the current NPDAO mechanism in		Even with the changed semantics, the current NPDAO mechanism in
	[RFC6550] can still be used. There are certain scenarios where		[RFC6550] can still be used, for example, when the route lifetime
	current NPDAO signalling may still be used, for example, when the		expiry of the target happens or when the node simply decides to
	route lifetime expiry of the target happens or when the node simply		gracefully terminate the RPL session on graceful node shutdown.
	decides to gracefully terminate the RPL session on graceful node		Moreover a deployment can have a mix of nodes supporting the proposed
	shutdown. Moreover a deployment can have a mix of nodes supporting		DCO and the existing NPDAO mechanism.
	the proposed DCO and the existing NPDAO mechanism.
			4.4.3. DCO with multiple preferred parents
			[RFC6550] allows a node to select multiple preferred parents for
			route establishment. DCO can be used for route invalidation in such
			cases as well. There are no changes required in the DCO messaging to
			support multiple preferred parents and DCO should work seemlessly in
			such scenarios.
	5. Acknowledgements		5. Acknowledgements
	Many thanks to Cenk Gundogan, Simon Duquennoy, Georgios		Many thanks to Cenk Gundogan, Simon Duquennoy, Georgios
	Papadopoulous, Peter Van Der Stok for their review and comments.		Papadopoulous, Peter Van Der Stok for their review and comments.
	6. IANA Considerations		6. IANA Considerations
	IANA is requested to allocate new ICMPv6 RPL control codes in RPL		IANA is requested to allocate new ICMPv6 RPL control codes in RPL
	[RFC6550] for DCO and DCO-ACK messages.		[RFC6550] for DCO and DCO-ACK messages.
	skipping to change at page 12, line 4 ¶		skipping to change at page 12, line 17 ¶
	+------+---------------------------------------------+--------------+		+------+---------------------------------------------+--------------+
	| 0x04 | Destination Cleanup Object | This |		| 0x04 | Destination Cleanup Object | This |
	| | | document |		| | | document |
	| 0x05 | Destination Cleanup Object Acknowledgement | This |		| 0x05 | Destination Cleanup Object Acknowledgement | This |
	| | | document |		| | | document |
	| 0x84 | Secure Destination Cleanup Object | This |		| 0x84 | Secure Destination Cleanup Object | This |
	| | | document |		| | | document |
	| 0x85 | Secure Destination Cleanup Object | This |		| 0x85 | Secure Destination Cleanup Object | This |
	| | Acknowledgement | document |		| | Acknowledgement | document |
	+------+---------------------------------------------+--------------+		+------+---------------------------------------------+--------------+
	IANA is requested to allocate bit 18 in the Transit Information		IANA is requested to allocate bit 18 in the Transit Information
	Option defined in RPL [RFC6550] section 6.7.8 for Invalidate route		Option defined in RPL [RFC6550] section 6.7.8 for Invalidate route
	'I' flag.		'I' flag.
	7. Security Considerations		7. Security Considerations
	This document handles security considerations inline to base RPL.		The document adds new messages (DCO, DCO-ACK) which are similar to
	Secure versions of DCO and DCO-ACK are added similar to other RPL		existing RPL messages such as DAO, DAO-ACK. Secure versions of DCO
	messages. For general RPL security considerations, see [RFC6550].		and DCO-ACK are added similar to other RPL messages (such as DAO,
			DAO-ACK). For general RPL security considerations, see [RFC6550].
	8. References		8. References
	8.1. Normative References		8.1. 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,
	<https://www.rfc-editor.org/info/rfc2119>.		<https://www.rfc-editor.org/info/rfc2119>.
End of changes. 16 change blocks.
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