< draft-ietf-roll-useofrplinfo-29.txt		draft-ietf-roll-useofrplinfo-30.txt >
	ROLL Working Group M. Robles		ROLL Working Group M. Robles
	Internet-Draft Aalto		Internet-Draft Aalto
	Updates: 6553, 6550, 8138 (if approved) M. Richardson		Updates: 6553, 6550, 8138 (if approved) M. Richardson
	Intended status: Standards Track SSW		Intended status: Standards Track SSW
	Expires: November 21, 2019 P. Thubert		Expires: December 27, 2019 P. Thubert
	Cisco		Cisco
	May 20, 2019		June 25, 2019
	Using RPL Option Type, Routing Header for Source Routes and IPv6-in-IPv6		Using RPL Option Type, Routing Header for Source Routes and IPv6-in-IPv6
	encapsulation in the RPL Data Plane		encapsulation in the RPL Data Plane
	draft-ietf-roll-useofrplinfo-29		draft-ietf-roll-useofrplinfo-30
	Abstract		Abstract
	This document looks at different data flows through LLN (Low-Power		This document looks at different data flows through LLN (Low-Power
	and Lossy Networks) where RPL (IPv6 Routing Protocol for Low-Power		and Lossy Networks) where RPL (IPv6 Routing Protocol for Low-Power
	and Lossy Networks) is used to establish routing. The document		and Lossy Networks) is used to establish routing. The document
	enumerates the cases where RFC6553 (RPL Option Type), RFC6554		enumerates the cases where RFC6553 (RPL Option Type), RFC6554
	(Routing Header for Source Routes) and IPv6-in-IPv6 encapsulation is		(Routing Header for Source Routes) and IPv6-in-IPv6 encapsulation is
	required in data plane. This analysis provides the basis on which to		required in data plane. This analysis provides the basis on which to
	design efficient compression of these headers. This document updates		design efficient compression of these headers. This document updates
	skipping to change at page 1, line 44 ¶		skipping to change at page 1, line 44 ¶
	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 November 21, 2019.		This Internet-Draft will expire on December 27, 2019.
	Copyright Notice		Copyright Notice
	Copyright (c) 2019 IETF Trust and the persons identified as the		Copyright (c) 2019 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 . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
	1.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 4		1.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 4
	2. Terminology and Requirements Language . . . . . . . . . . . . 5		2. Terminology and Requirements Language . . . . . . . . . . . . 4
	3. Updates to RFC6553, RFC6550 and RFC8138 . . . . . . . . . . . 6		3. RPL Overview . . . . . . . . . . . . . . . . . . . . . . . . 6
	3.1. Updates to RFC6553: Indicating the new RPI value. . . . . 6		4. Updates to RFC6553, RFC6550 and RFC8138 . . . . . . . . . . . 7
	3.2. Updates to RFC6550: Indicating the new RPI in the		4.1. Updates to RFC6553: Indicating the new RPI value. . . . . 7
			4.2. Updates to RFC6550: Indicating the new RPI in the
	DODAG Configuration Option Flag. . . . . . . . . . . . . 10		DODAG Configuration Option Flag. . . . . . . . . . . . . 10
	3.3. Updates to RFC8138: Indicating the way to decompress with		4.3. Updates to RFC8138: Indicating the way to decompress with
	the new RPI value. . . . . . . . . . . . . . . . . . . . 11		the new RPI value. . . . . . . . . . . . . . . . . . . . 11
	4. Sample/reference topology . . . . . . . . . . . . . . . . . . 11		5. Sample/reference topology . . . . . . . . . . . . . . . . . . 12
	5. Use cases . . . . . . . . . . . . . . . . . . . . . . . . . . 14		6. Use cases . . . . . . . . . . . . . . . . . . . . . . . . . . 14
	6. Storing mode . . . . . . . . . . . . . . . . . . . . . . . . 16		7. Storing mode . . . . . . . . . . . . . . . . . . . . . . . . 16
	6.1. Storing Mode: Interaction between Leaf and Root . . . . . 17		7.1. Storing Mode: Interaction between Leaf and Root . . . . . 18
	6.1.1. SM: Example of Flow from RPL-aware-leaf to root . . . 17		7.1.1. SM: Example of Flow from RAL to root . . . . . . . . 18
	6.1.2. SM: Example of Flow from root to RPL-aware-leaf . . . 19		7.1.2. SM: Example of Flow from root to RAL . . . . . . . . 19
	6.1.3. SM: Example of Flow from root to not-RPL-aware-leaf . 19		7.1.3. SM: Example of Flow from root to RUL . . . . . . . . 20
	6.1.4. SM: Example of Flow from not-RPL-aware-leaf to root . 20		7.1.4. SM: Example of Flow from RUL to root . . . . . . . . 20
	6.2. Storing Mode: Interaction between Leaf and Internet. . . 21		7.2. SM: Interaction between Leaf and Internet. . . . . . . . 21
	6.2.1. SM: Example of Flow from RPL-aware-leaf to Internet . 21		7.2.1. SM: Example of Flow from RAL to Internet . . . . . . 22
	6.2.2. SM: Example of Flow from Internet to RPL-aware-leaf . 22		7.2.2. SM: Example of Flow from Internet to RAL . . . . . . 22
	6.2.3. SM: Example of Flow from not-RPL-aware-leaf to		7.2.3. SM: Example of Flow from RUL to Internet . . . . . . 23
	Internet . . . . . . . . . . . . . . . . . . . . . . 23		7.2.4. SM: Example of Flow from Internet to RUL. . . . . . . 24
	6.2.4. SM: Example of Flow from Internet to not-RPL-aware-		7.3. SM: Interaction between Leaf and Leaf . . . . . . . . . . 25
	leaf. . . . . . . . . . . . . . . . . . . . . . . . . 24		7.3.1. SM: Example of Flow from RAL to RAL . . . . . . . . . 25
	6.3. Storing Mode: Interaction between Leaf and Leaf . . . . . 25		7.3.2. SM: Example of Flow from RAL to RUL . . . . . . . . . 27
	6.3.1. SM: Example of Flow from RPL-aware-leaf to RPL-aware-		7.3.3. SM: Example of Flow from RUL to RAL . . . . . . . . . 27
	leaf . . . . . . . . . . . . . . . . . . . . . . . . 25		7.3.4. SM: Example of Flow from RUL to RUL . . . . . . . . . 29
	6.3.2. SM: Example of Flow from RPL-aware-leaf to not-RPL-		8. Non Storing mode . . . . . . . . . . . . . . . . . . . . . . 30
	aware-leaf . . . . . . . . . . . . . . . . . . . . . 26		8.1. Non-Storing Mode: Interaction between Leaf and Root . . . 31
	6.3.3. SM: Example of Flow from not-RPL-aware-leaf to RPL-		8.1.1. Non-SM: Example of Flow from RAL to root . . . . . . 32
	aware-leaf . . . . . . . . . . . . . . . . . . . . . 27		8.1.2. Non-SM: Example of Flow from root to RAL . . . . . . 32
			8.1.3. Non-SM: Example of Flow from root to RUL . . . . . . 33
	6.3.4. SM: Example of Flow from not-RPL-aware-leaf to not-		8.1.4. Non-SM: Example of Flow from RUL to root . . . . . . 34
	RPL-aware-leaf . . . . . . . . . . . . . . . . . . . 29		8.2. Non-Storing Mode: Interaction between Leaf and Internet . 35
	7. Non Storing mode . . . . . . . . . . . . . . . . . . . . . . 30		8.2.1. Non-SM: Example of Flow from RAL to Internet . . . . 35
	7.1. Non-Storing Mode: Interaction between Leaf and Root . . . 31		8.2.2. Non-SM: Example of Flow from Internet to RAL . . . . 36
	7.1.1. Non-SM: Example of Flow from RPL-aware-leaf to root . 32		8.2.3. Non-SM: Example of Flow from RUL to Internet . . . . 37
	7.1.2. Non-SM: Example of Flow from root to RPL-aware-leaf . 32		8.2.4. Non-SM: Example of Flow from Internet to RUL . . . . 38
	7.1.3. Non-SM: Example of Flow from root to not-RPL-aware-		8.3. Non-SM: Interaction between Leafs . . . . . . . . . . . . 39
	leaf . . . . . . . . . . . . . . . . . . . . . . . . 33		8.3.1. Non-SM: Example of Flow from RAL to RAL . . . . . . . 39
	7.1.4. Non-SM: Example of Flow from not-RPL-aware-leaf to		8.3.2. Non-SM: Example of Flow from RAL to RUL . . . . . . . 41
	root . . . . . . . . . . . . . . . . . . . . . . . . 34		8.3.3. Non-SM: Example of Flow from RUL to RAL . . . . . . . 42
	7.2. Non-Storing Mode: Interaction between Leaf and Internet . 35		8.3.4. Non-SM: Example of Flow from RUL to RUL . . . . . . . 43
	7.2.1. Non-SM: Example of Flow from RPL-aware-leaf to		9. Operational Considerations of supporting
	Internet . . . . . . . . . . . . . . . . . . . . . . 35
	7.2.2. Non-SM: Example of Flow from Internet to RPL-aware-
	leaf . . . . . . . . . . . . . . . . . . . . . . . . 36
	7.2.3. Non-SM: Example of Flow from not-RPL-aware-leaf to
	Internet . . . . . . . . . . . . . . . . . . . . . . 37
	7.2.4. Non-SM: Example of Flow from Internet to not-RPL-
	aware-leaf . . . . . . . . . . . . . . . . . . . . . 38
	7.3. Non-Storing Mode: Interaction between Leafs . . . . . . . 39
	7.3.1. Non-SM: Example of Flow from RPL-aware-leaf to RPL-
	aware-leaf . . . . . . . . . . . . . . . . . . . . . 39
	7.3.2. Non-SM: Example of Flow from RPL-aware-leaf to not-
	RPL-aware-leaf . . . . . . . . . . . . . . . . . . . 41
	7.3.3. Non-SM: Example of Flow from not-RPL-aware-leaf to
	RPL-aware-leaf . . . . . . . . . . . . . . . . . . . 42
	7.3.4. Non-SM: Example of Flow from not-RPL-aware-leaf to
	not-RPL-aware-leaf . . . . . . . . . . . . . . . . . 43
	8. Operational Considerations of supporting
	not-RPL-aware-leaves . . . . . . . . . . . . . . . . . . . . 44		not-RPL-aware-leaves . . . . . . . . . . . . . . . . . . . . 44
	9. Operational considerations of introducing 0x23 . . . . . . . 45		10. Operational considerations of introducing 0x23 . . . . . . . 45
	10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 46		11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 46
	11. Security Considerations . . . . . . . . . . . . . . . . . . . 47		12. Security Considerations . . . . . . . . . . . . . . . . . . . 47
	12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 50		13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 50
	13. References . . . . . . . . . . . . . . . . . . . . . . . . . 50		14. References . . . . . . . . . . . . . . . . . . . . . . . . . 50
	13.1. Normative References . . . . . . . . . . . . . . . . . . 50		14.1. Normative References . . . . . . . . . . . . . . . . . . 50
	13.2. Informative References . . . . . . . . . . . . . . . . . 51		14.2. Informative References . . . . . . . . . . . . . . . . . 51
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 54		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 53
	1. Introduction		1. Introduction
	RPL (IPv6 Routing Protocol for Low-Power and Lossy Networks)		RPL (IPv6 Routing Protocol for Low-Power and Lossy Networks)
	[RFC6550] is a routing protocol for constrained networks. RFC6553		[RFC6550] is a routing protocol for constrained networks. RFC6553
	[RFC6553] defines the "RPL option" (RPL Packet Information or RPI),		[RFC6553] defines the "RPL option" (RPL Packet Information or RPI),
	carried within the IPv6 Hop-by-Hop header to quickly identify		carried within the IPv6 Hop-by-Hop header to quickly identify
	inconsistencies (loops) in the routing topology. RFC6554 [RFC6554]		inconsistencies (loops) in the routing topology. RFC6554 [RFC6554]
	defines the "RPL Source Route Header" (RH3), an IPv6 Extension Header		defines the "RPL Source Route Header" (RH3), an IPv6 Extension Header
	to deliver datagrams within a RPL routing domain, particularly in		to deliver datagrams within a RPL routing domain, particularly in
	skipping to change at page 4, line 39 ¶		skipping to change at page 4, line 23 ¶
	mechanism for compressing RPL Option information and Routing Header		mechanism for compressing RPL Option information and Routing Header
	type 3 (RH3) [RFC6554], as well as an efficient IPv6-in-IPv6		type 3 (RH3) [RFC6554], as well as an efficient IPv6-in-IPv6
	technique.		technique.
	Since some of the uses cases here described, use IPv6-in-IPv6		Since some of the uses cases here described, use IPv6-in-IPv6
	encapsulation. It MUST take in consideration, when encapsulation is		encapsulation. It MUST take in consideration, when encapsulation is
	applied, the RFC6040 [RFC6040], which defines how the explicit		applied, the RFC6040 [RFC6040], which defines how the explicit
	congestion notification (ECN) field of the IP header should be		congestion notification (ECN) field of the IP header should be
	constructed on entry to and exit from any IPV6-in-IPV6 tunnel.		constructed on entry to and exit from any IPV6-in-IPV6 tunnel.
	Additionally, it is recommended the reading of		Additionally, it is recommended the reading of
	[I-D.ietf-intarea-tunnels].		[I-D.ietf-intarea-tunnels] that explains the relationship of IP
			tunnels to existing protocol layers and the challenges in supporting
			IP tunneling.
			Non-constrained uses of RPL are not in scope of this document, and
			applicability statements for those uses may provide different advice,
			E.g. [I-D.ietf-anima-autonomic-control-plane].
	1.1. Overview		1.1. Overview
	The rest of the document is organized as follows: Section 2 describes		The rest of the document is organized as follows: Section 2 describes
	the used terminology. Section 3 describes the updates to RFC6553,		the used terminology. Section 3 describes the updates to RFC6553,
	RFC6550 and RFC 8138. Section 4 provides the reference topology used		RFC6550 and RFC 8138. Section 4 provides the reference topology used
	for the uses cases. Section 5 describes the uses cases included.		for the uses cases. Section 5 describes the uses cases included.
	Section 6 describes the storing mode cases and section 7 the non-		Section 6 describes the storing mode cases and section 7 the non-
	storing mode cases. Section 8 describes the operational		storing mode cases. Section 8 describes the operational
	considerations of supporting not-RPL-aware-leaves. Section 9 depicts		considerations of supporting not-RPL-aware-leaves. Section 9 depicts
	skipping to change at page 5, line 15 ¶		skipping to change at page 5, line 5 ¶
	describes the security aspects.		describes the security aspects.
	2. Terminology and Requirements Language		2. Terminology and 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 BCP
	14 [RFC2119] [RFC8174] when, and only when, they appear in all		14 [RFC2119] [RFC8174] when, and only when, they appear in all
	capitals, as shown here.		capitals, as shown here.
	Terminology defined in [RFC7102] applies to this document: LBR, LLN,		Terminology defined in [RFC7102] applies to this document: LLN, RPL,
	RPL, RPL Domain and ROLL.		RPL Domain and ROLL.
	RPL-node: A device which implements RPL, thus the device is RPL-		RPL-aware-node: A device which implements RPL. Please note that the
	aware. Please note that the device can be found inside the LLN or		device can be found inside the LLN or outside LLN.
	outside LLN. In this document a RPL-node which is a leaf of a
	(Destination Oriented Directed Acyclic Graph) DODAG is called RPL-
	aware-leaf (Raf).
	RPL-not-capable: A device which does not implement RPL, thus the		RPL-Aware-Leaf(RAL): A RPL-aware-node which is a leaf of a
			(Destination Oriented Directed Acyclic Graph) DODAG.
			RPL-unaware-node: A device which does not implement RPL, thus the
	device is not-RPL-aware. Please note that the device can be found		device is not-RPL-aware. Please note that the device can be found
	inside the LLN. In this document a not-RPL-aware node which is a		inside the LLN.
	leaf of a DODAG is called not-RPL-aware-leaf (~Raf).
	6LN: [RFC6775] defines it as: "A 6LoWPAN node is any host or router		RPL-Unaware-Leaf(RUL): A RPL-unaware-node which is a leaf of a
	participating in a LoWPAN. This term is used when referring to		(Destination Oriented Directed Acyclic Graph) DODAG.
	situations in which either a host or router can play the role
	described.". In this document, a 6LN acts as a leaf.
	6LR: [RFC6775] defines it as:" An intermediate router in the LoWPAN		6LoWPAN Node (6LN): [RFC6775] defines it as: "A 6LoWPAN node is any
	that is able to send and receive Router Advertisements (RAs) and		host or router participating in a LoWPAN. This term is used when
	Router Solicitations (RSs) as well as forward and route IPv6 packets.		referring to situations in which either a host or router can play the
	6LoWPAN routers are present only in route-over topologies."		role described.". In this document, a 6LN acts as a leaf.
	6LBR: [RFC6775] defines it as:"A border router located at the		6LoWPAN Router (6LR): [RFC6775] defines it as:" An intermediate
	junction of separate 6LoWPAN networks or between a 6LoWPAN network		router in the LoWPAN that is able to send and receive Router
	and another IP network. There may be one or more 6LBRs at the		Advertisements (RAs) and Router Solicitations (RSs) as well as
	6LoWPAN network boundary. A 6LBR is the responsible authority for		forward and route IPv6 packets. 6LoWPAN routers are present only in
	IPv6 prefix propagation for the 6LoWPAN network it is serving. An		route-over topologies."
	isolated LoWPAN also contains a 6LBR in the network, which provides
	the prefix(es) for the isolated network."		6LoWPAN Border Router (6LBR): [RFC6775] defines it as:"A border
			router located at the junction of separate 6LoWPAN networks or
			between a 6LoWPAN network and another IP network. There may be one
			or more 6LBRs at the 6LoWPAN network boundary. A 6LBR is the
			responsible authority for IPv6 prefix propagation for the 6LoWPAN
			network it is serving. An isolated LoWPAN also contains a 6LBR in
			the network, which provides the prefix(es) for the isolated network."
	Flag Day: A transition that involves having a network with different		Flag Day: A transition that involves having a network with different
	values of RPL Option Type. Thus the network does not work correctly.		values of RPL Option Type. Thus the network does not work correctly
			(Lack of interoperation).
	Hop-by-hop re-encapsulation: The term "hop-by-hop re-encapsulation"		Hop-by-hop re-encapsulation: The term "hop-by-hop re-encapsulation"
	header refers to adding a header that originates from a node to an		header refers to adding a header that originates from a node to an
	adjacent node, using the addresses (usually the GUA or ULA, but could		adjacent node, using the addresses (usually the GUA or ULA, but could
	use the link-local addresses) of each node. If the packet must		use the link-local addresses) of each node. If the packet must
	traverse multiple hops, then it must be decapsulated at each hop, and		traverse multiple hops, then it must be decapsulated at each hop, and
	then re-encapsulated again in a similar fashion.		then re-encapsulated again in a similar fashion.
			Non-storing Mode (Non-SM): RPL mode of operation in which the RPL-
			aware-nodes send information to the root about its parents. Thus,
			the root know the topology, then the intermediate 6LRs do not
			maintain routing state so that source routing is needed.
			Storing Mode (SM): RPL mode of operation in which RPL-aware-nodes
			(6LRs) maintain routing state (of the children) so that source
			routing is not needed.
			Due to lack of space in some figures (tables) we refers IPv6-in-IPv6
			as IP6-IP6.
			3. RPL Overview
	RPL defines the RPL Control messages (control plane), a new ICMPv6		RPL defines the RPL Control messages (control plane), a new ICMPv6
	[RFC4443] message with Type 155. DIS (DODAG Information		[RFC4443] message with Type 155. DIS (DODAG Information
	Solicitation), DIO (DODAG Information Object) and DAO (Destination		Solicitation), DIO (DODAG Information Object) and DAO (Destination
	Advertisement Object) messages are all RPL Control messages but with		Advertisement Object) messages are all RPL Control messages but with
	different Code values. A RPL Stack is shown in Figure 1.		different Code values. A RPL Stack is shown in Figure 1.
	+--------------+		+--------------+
	| Upper Layers |		| Upper Layers |
	| |		| |
	+--------------+		+--------------+
	skipping to change at page 6, line 37 ¶		skipping to change at page 6, line 44 ¶
	+--------------+		+--------------+
	| 6LoWPAN |		| 6LoWPAN |
	| |		| |
	+--------------+		+--------------+
	| PHY-MAC |		| PHY-MAC |
	| |		| |
	+--------------+		+--------------+
	Figure 1: RPL Stack.		Figure 1: RPL Stack.
	RPL supports two modes of Downward traffic: in storing mode (RPL-SM),		RPL supports two modes of Downward traffic: in storing mode (SM), it
	it is fully stateful; in non-storing mode (RPL-NSM), it is fully		is fully stateful; in non-storing mode (Non-SM), it is fully source
	source routed. A RPL Instance is either fully storing or fully non-		routed. A RPL Instance is either fully storing or fully non-storing,
	storing, i.e. a RPL Instance with a combination of storing and non-		i.e. a RPL Instance with a combination of storing and non-storing
	storing nodes is not supported with the current specifications at the		nodes is not supported with the current specifications at the time of
	time of writing this document.		writing this document.
	3. Updates to RFC6553, RFC6550 and RFC8138		4. Updates to RFC6553, RFC6550 and RFC8138
	3.1. Updates to RFC6553: Indicating the new RPI value.		4.1. Updates to RFC6553: Indicating the new RPI value.
	This modification is required to be able to send, for example, IPv6		This modification is required to be able to send, for example, IPv6
	packets from a RPL-aware-leaf to a not-RPL-aware node through		packets from a RPL-Aware-Leaf to a not-RPL-aware node through
	Internet (see Section 6.2.1), without requiring IPv6-in-IPv6		Internet (see Section 7.2.1), without requiring IPv6-in-IPv6
	encapsulation.		encapsulation.
	[RFC6553] (Section 6, Page 7) states as shown in Figure 2, that in		[RFC6553] (Section 6, Page 7) states as shown in Figure 2, that in
	the Option Type field of the RPL Option header, the two high order		the Option Type field of the RPL Option header, the two high order
	bits must be set to '01' and the third bit is equal to '1'. The		bits must be set to '01' and the third bit is equal to '1'. The
	first two bits indicate that the IPv6 node must discard the packet if		first two bits indicate that the IPv6 node must discard the packet if
	it doesn't recognize the option type, and the third bit indicates		it doesn't recognize the option type, and the third bit indicates
	that the Option Data may change in route. The remaining bits serve		that the Option Data may change in route. The remaining bits serve
	as the option type.		as the option type.
	skipping to change at page 7, line 37 ¶		skipping to change at page 7, line 46 ¶
	At the time [RFC6553] was published, leaking a Hop-by-Hop header in		At the time [RFC6553] was published, leaking a Hop-by-Hop header in
	the outer IPv6 header chain could potentially impact core routers in		the outer IPv6 header chain could potentially impact core routers in
	the internet. So at that time, it was decided to encapsulate any		the internet. So at that time, it was decided to encapsulate any
	packet with a RPL option using IPv6-in-IPv6 in all cases where it was		packet with a RPL option using IPv6-in-IPv6 in all cases where it was
	unclear whether the packet would remain within the RPL domain. In		unclear whether the packet would remain within the RPL domain. In
	the exception case where a packet would still leak, the Option Type		the exception case where a packet would still leak, the Option Type
	would ensure that the first router in the Internet that does not		would ensure that the first router in the Internet that does not
	recognize the option would drop the packet and protect the rest of		recognize the option would drop the packet and protect the rest of
	the network.		the network.
	Even with [RFC8138] that compresses the IP-in-IP header, this		Even with [RFC8138] that compresses the IPv6-in-IPv6 header, this
	approach yields extra bytes in a packet which means consuming more		approach yields extra bytes in a packet which means consuming more
	energy, more bandwidth, incurring higher chances of loss and possibly		energy, more bandwidth, incurring higher chances of loss and possibly
	causing a fragmentation at the 6LoWPAN level. This impacts the daily		causing a fragmentation at the 6LoWPAN level. This impacts the daily
	operation of constrained devices for a case that generally does not		operation of constrained devices for a case that generally does not
	happen and would not heavily impact the core anyway.		happen and would not heavily impact the core anyway.
	While intention was and remains that the Hop-by-Hop header with a RPL		While intention was and remains that the Hop-by-Hop header with a RPL
	option should be confined within the RPL domain, this specification		option should be confined within the RPL domain, this specification
	modifies this behavior in order to reduce the dependency on IP-in-IP		modifies this behavior in order to reduce the dependency on IPv6-in-
	and protect the constrained devices. Section 4 of [RFC8200]		IPv6 and protect the constrained devices. Section 4 of [RFC8200]
	clarifies the behaviour of routers in the Internet as follows: "it is		clarifies the behaviour of routers in the Internet as follows: "it is
	now expected that nodes along a packet's delivery path only examine		now expected that nodes along a packet's delivery path only examine
	and process the Hop-by-Hop Options header if explicitly configured to		and process the Hop-by-Hop Options header if explicitly configured to
	do so". This means that while it should be avoided, the impact on		do so".
	the Internet of leaking a Hop-by-Hop header is acceptable.
	When unclear about the travel of a packet, it becomes preferable for		When unclear about the travel of a packet, it becomes preferable for
	a source not to encapsulate, accepting the fact that the packet may		a source not to encapsulate, accepting the fact that the packet may
	leave the RPL domain on its way to its destination. In that event,		leave the RPL domain on its way to its destination. In that event,
	the packet should reach its destination and should not be discarded		the packet should reach its destination and should not be discarded
	by the first node that does not recognize the RPL option. But with		by the first node that does not recognize the RPL option. But with
	the current value of the Option Type, if a node in the Internet is		the current value of the Option Type, if a node in the Internet is
	configured to process the Hop-by-Hop header, and if such node		configured to process the Hop-by-Hop header, and if such node
	encounters an option with the first two bits set to 01 and conforms		encounters an option with the first two bits set to 01 and conforms
	to [RFC8200], it will drop the packet. Host systems should do the		to [RFC8200], it will drop the packet. Host systems should do the
	skipping to change at page 8, line 31 ¶		skipping to change at page 8, line 40 ¶
	bit continues to be set to indicate that the Option Data may change		bit continues to be set to indicate that the Option Data may change
	en route. The remaining bits serve as the option type and remain as		en route. The remaining bits serve as the option type and remain as
	0x3. This ensures that a packet that leaves the RPL domain of an LLN		0x3. This ensures that a packet that leaves the RPL domain of an LLN
	(or that leaves the LLN entirely) will not be discarded when it		(or that leaves the LLN entirely) will not be discarded when it
	contains the [RFC6553] RPL Hop-by-Hop option known as RPI.		contains the [RFC6553] RPL Hop-by-Hop option known as RPI.
	With the new Option Type, if an IPv6 (intermediate) node (RPL-not-		With the new Option Type, if an IPv6 (intermediate) node (RPL-not-
	capable) receives a packet with an RPL Option, it should ignore the		capable) receives a packet with an RPL Option, it should ignore the
	Hop-by-Hop RPL option (skip over this option and continue processing		Hop-by-Hop RPL option (skip over this option and continue processing
	the header). This is relevant, as it was mentioned previously, in		the header). This is relevant, as it was mentioned previously, in
	the case that there is a flow from RPL-aware-leaf to Internet (see		the case that there is a flow from RAL to Internet (see
	Section 6.2.1).		Section 7.2.1).
	This is a significant update to [RFC6553].		This is a significant update to [RFC6553].
	+-------+-------------------+-------------+------------+		+-------+-------------------+-------------+------------+
	| Hex | Binary Value | Description | Reference |		| Hex | Binary Value | Description | Reference |
	+ Value +-------------------+ + +		+ Value +-------------------+ + +
	| | act | chg | rest | | |		| | act | chg | rest | | |
	+-------+-----+-----+-------+-------------+------------+		+-------+-----+-----+-------+-------------+------------+
	| 0x23 | 00 | 1 | 00011 | RPL Option |[RFCXXXX](*)|		| 0x23 | 00 | 1 | 00011 | RPL Option |[RFCXXXX](*)|
	+-------+-----+-----+-------+-------------+------------+		+-------+-----+-----+-------+-------------+------------+
	Figure 3: Revised Option Type in RPL Option. (*)represents this		Figure 3: Revised Option Type in RPL Option. (*)represents this
	document		document
	Without the signaling described below, this change would otherwise		Without the signaling described below, this change would otherwise
	create a flag day for existing networks which are currently using		create a lack of interoperation (flag day) for existing networks
	0x63 as the RPI value. A move to 0x23 will not be understood by		which are currently using 0x63 as the RPI value. A move to 0x23 will
	those networks. It is suggested that implementations accept both		not be understood by those networks. It is suggested that RPL
	0x63 and 0x23 when processing.		implementations accept both 0x63 and 0x23 when processing the header.
	When forwarding packets, implementations SHOULD use the same value as		When forwarding packets, implementations SHOULD use the same value as
	it was received (This is required because, RPI type code can not be		it was received (This is required because, RPI type code can not be
	changed by [RFC8200]). It allows to the network to be incrementally		changed by [RFC8200] - Section 4.2). It allows to the network to be
	upgraded, and for the DODAG root to know which parts of the network		incrementally upgraded, and for the DODAG root to know which parts of
	are upgraded.		the network are upgraded.
	When originating new packets, implementations SHOULD have an option		When originating new packets, implementations SHOULD have an option
	to determine which value to originate with, this option is controlled		to determine which value to originate with, this option is controlled
	by the DIO option described below.		by the DIO option described below.
	A network which is switching from straight 6lowpan compression		A network which is switching from straight 6LoWPAN compression
	mechanism to those described in [RFC8138] will experience a flag day		mechanism to those described in [RFC8138] will experience a flag day
	in the data compression anyway, and if possible this change can be		in the data compression anyway, and if possible this change can be
	deployed at the same time.		deployed at the same time.
	The change of RPI option type from 0x63 to 0x23, makes all [RFC8200]		The change of RPI option type from 0x63 to 0x23, makes all [RFC8200]
	Section 4.2 compliant nodes tolerant of the RPL artifacts. There is		Section 4.2 compliant nodes tolerant of the RPL artifacts. There is
	therefore no longer a necessity to remove the artifacts when sending		therefore no longer a necessity to remove the artifacts when sending
	traffic to the Internet. This change clarifies when to use an IPv6-		traffic to the Internet. This change clarifies when to use an IPv6-
	in-IPv6 header, and how to address them: The Hop-by-Hop Options		in-IPv6 header, and how to address them: The Hop-by-Hop Options
	Header containing the RPI option MUST always be added when 6LRs		Header containing the RPI option MUST always be added when 6LRs
	originate packets (without IPv6-in-IPv6 headers), and IPv6-in-IPv6		originate packets (without IPv6-in-IPv6 headers), and IPv6-in-IPv6
	headers MUST always be added when a 6LR find that it needs to insert		headers MUST always be added when a 6LR find that it needs to insert
	a Hop-by-Hop Options Header containing the RPI option. The IPv6-in-		a Hop-by-Hop Options Header containing the RPI option. The IPv6-in-
	IPv6 header is to be addressed to the RPL root when on the way up,		IPv6 header is to be addressed to the RPL root when on the way up,
	and to the end-host when on the way down.		and to the end-host when on the way down.
	Non-constrained uses of RPL are not in scope of this document, and
	applicability statements for those uses may provide different advice,
	E.g. [I-D.ietf-anima-autonomic-control-plane].
	In the non-storing case, dealing with not-RPL aware leaf nodes is		In the non-storing case, dealing with not-RPL aware leaf nodes is
	much easier as the 6LBR (DODAG root) has complete knowledge about the		much easier as the 6LBR (DODAG root) has complete knowledge about the
	connectivity of all DODAG nodes, and all traffic flows through the		connectivity of all DODAG nodes, and all traffic flows through the
	root node.		root node.
	The 6LBR can recognize not-RPL aware leaf nodes because it will		The 6LBR can recognize not-RPL aware leaf nodes because it will
	receive a DAO about that node from the 6LR immediately above that		receive a DAO about that node from the 6LR immediately above that
	not-RPL aware node. This means that the non-storing mode case can		not-RPL aware node. This means that the non-storing mode case can
	avoid ever using hop-by-hop re-encapsulation headers for traffic		avoid ever using hop-by-hop re-encapsulation headers for traffic
	originating from the root to the leafs.		originating from the root to the leafs.
	The non-storing mode case does not require the type change from 0x63		The non-storing mode case does not require the type change from 0x63
	to 0x23, as the root can always create the right packet. The type		to 0x23, as the root can always create the right packet. The type
	change does not adversely affect the non-storing case.		change does not adversely affect the non-storing case.
	3.2. Updates to RFC6550: Indicating the new RPI in the DODAG		4.2. Updates to RFC6550: Indicating the new RPI in the DODAG
	Configuration Option Flag.		Configuration Option Flag.
	In order to avoid a Flag Day caused by lack of interoperation between		In order to avoid a Flag Day caused by lack of interoperation between
	new RPI (0x23) and old RPI (0x63) nodes, this section defines a flag		new RPI (0x23) and old RPI (0x63) nodes, this section defines a flag
	in the DIO Configuration Option, to indicate when then new RPI value		in the DIO Configuration Option, to indicate when then new RPI value
	can be safely used. This means, the flag is going to indicate the		can be safely used. This means, the flag is going to indicate the
	type of RPI that the network is using. Thus, when a node join to a		type of RPI that the network is using. Thus, when a node join to a
	network will know which value to use. With this, RPL-capable nodes		network will know which value to use. With this, RPL-capable nodes
	know if it is safe to use 0x23 when creating a new RPI. A node that		know if it is safe to use 0x23 when creating a new RPI. A node that
	forwards a packet with an RPI MUST NOT modify the option type of the		forwards a packet with an RPI MUST NOT modify the option type of the
	skipping to change at page 10, line 48 ¶		skipping to change at page 11, line 14 ¶
	+------------+-----------------+---------------+		+------------+-----------------+---------------+
	| Bit number | Description | Reference |		| Bit number | Description | Reference |
	+------------+-----------------+---------------+		+------------+-----------------+---------------+
	| 3 | RPI 0x23 enable | This document |		| 3 | RPI 0x23 enable | This document |
	+------------+-----------------+---------------+		+------------+-----------------+---------------+
	Figure 4: DODAG Configuration Option Flag to indicate the RPI-flag-		Figure 4: DODAG Configuration Option Flag to indicate the RPI-flag-
	day.		day.
	In case of rebooting, the node (6LN or 6LR) does not remember if the		In case of rebooting, the node (6LN or 6LR) does not remember the RPL
	flag is set, so DIO messages would be set with the flag unset until a		Option Type, that is if the flag is set, so DIO messages sent by the
	DIO is received with the flag set.		node would be set with the flag unset until a DIO message is received
			with the flag set indicating the new RPI value. The node sets to
			0x23 if the node supports this feature.
	3.3. Updates to RFC8138: Indicating the way to decompress with the new		4.3. Updates to RFC8138: Indicating the way to decompress with the new
	RPI value.		RPI value.
	This modification is required to be able to decompress the RPL RPI		This modification is required to be able to decompress the RPL RPI
	option with the new value (0x23).		option with the new value (0x23).
	RPI-6LoRH header provides a compressed form for the RPL RPI [RFC8138]		RPI-6LoRH header provides a compressed form for the RPL RPI [RFC8138]
	in section 6. A node that is decompressing this header MUST		in section 6. A node that is decompressing this header MUST
	decompress using the RPL RPI option type that is currently active:		decompress using the RPL RPI option type that is currently active:
	that is, a choice between 0x23 (new) and 0x63 (old). The node will		that is, a choice between 0x23 (new) and 0x63 (old). The node will
	know which to use based upon the presence of the flag in the DODAG		know which to use based upon the presence of the flag in the DODAG
	Configuration Option defined in Section 3.2. E.g. If the network is		Configuration Option defined in Section 4.2. E.g. If the network is
	in 0x23 mode (by DIO option), then it should be decompressed to 0x23.		in 0x23 mode (by DIO option), then it should be decompressed to 0x23.
	[RFC8138] section 7 documents how to compress the IPv6-in-IPv6		[RFC8138] section 7 documents how to compress the IPv6-in-IPv6
	header.		header.
	There are potential significant advantages to having a single code		There are potential significant advantages to having a single code
	path that always processes IPv6-in-IPv6 headers with no conditional		path that always processes IPv6-in-IPv6 headers with no conditional
	branches.		branches.
	In Storing Mode, for the examples of Flow from RPL-aware-leaf to not-		In Storing Mode, for the examples of Flow from RAL to RUL and RUL to
	RPL-aware-leaf and not-RPL-aware-leaf to not-RPL-aware-leaf comprise		RUL comprise an IPv6-in-IPv6 and RPI compression headers. The use of
	an IPv6-in-IPv6 and RPI compression headers. The use of the IPv6-in-		the IPv6-in-IPv6 header is MANDATORY in this case, and it SHOULD be
	IPv6 header is MANDATORY in this case, and it SHOULD be compressed		compressed with [RFC8138] section 7. As exemplification of
	with [RFC8138] section 7. As exemplification of compressing the RPI,		compressing the RPI, section A.1 of [RFC8138] illustrates the case in
	section A.1 of [RFC8138] illustrates the case in Storing mode where		Storing mode where the packet is received from the Internet, then the
	the packet is received from the Internet, then the root encapsulates		root encapsulates the packet to insert the RPI. The result is shown
	the packet to insert the RPI. The result is shown in Figure 5.		in Figure 5.
	+-+ ... -+-+-...-+-+-- ... -+-+-+-+- ... -+-+ ... -+-+-+ ... -+-+-+...		+-+ ... -+-+-...-+-+-- ... -+-+-+-+- ... -+-+ ... -+-+-+ ... -+-+-+...
	|11110001| RPI- | IP-in-IP | NH=1 |11110CPP| Compressed | UDP		|11110001| RPI- | IP-in-IP | NH=1 |11110CPP| Compressed | UDP
	|Page 1 | 6LoRH | 6LoRH | LOWPAN_IPHC | UDP | UDP header | Payld		|Page 1 | 6LoRH | 6LoRH | LOWPAN_IPHC | UDP | UDP header | Payld
	+-+ ... -+-+-...-+-+-- ... -+-+-+-+- ... -+-+ ... -+-+-+ ... -+-+-+...		+-+ ... -+-+-...-+-+-- ... -+-+-+-+- ... -+-+ ... -+-+-+ ... -+-+-+...
	Figure 5: RPI Inserted by the Root in Storing Mode		Figure 5: RPI Inserted by the Root in Storing Mode
	4. Sample/reference topology		5. Sample/reference topology
	A RPL network in general is composed of a 6LBR (6LoWPAN Border		A RPL network in general is composed of a 6LBR, Backbone Router
	Router), Backbone Router (6BBR), 6LR (6LoWPAN Router) and 6LN		(6BBR), 6LR and 6LN as leaf logically organized in a DODAG structure.
	(6LoWPAN Node) as leaf logically organized in a DODAG structure.
	Figure 6 shows the reference RPL Topology for this document. The		Figure 6 shows the reference RPL Topology for this document. The
	letters above the nodes are there so that they may be referenced in		letters above the nodes are there so that they may be referenced in
	subsequent sections. In the figure, 6LR represents a full router		subsequent sections. In the figure, 6LR represents a full router
	node. The 6LN is a RPL aware router, or host (as a leaf).		node. The 6LN is a RPL aware router, or host (as a leaf).
	Additionally, for simplification purposes, it is supposed that the		Additionally, for simplification purposes, it is supposed that the
	6LBR has direct access to Internet, thus the 6BBR is not present in		6LBR has direct access to Internet, thus the 6BBR is not present in
	the figure.		the figure.
	The 6LN leaves (Raf) marked as (F, H and I) are RPL nodes with no		The 6LN leaves (RAL) marked as (F, H and I) are RPL nodes with no
	children hosts.		children hosts.
	The leafs marked as ~Raf (G and J) are devices which do not speak RPL		The leafs marked as RUL (G and J) are devices which do not speak RPL
	at all (not-RPL-aware), but uses Router-Advertisements, 6LowPAN DAR/		at all (not-RPL-aware), but uses Router-Advertisements, 6LowPAN DAR/
	DAC and efficient-ND only to participate in the network [RFC6775].		DAC and efficient-ND only to participate in the network [RFC6775].
	In the document these leafs (G and J) are also referred to as an IPv6		In the document these leafs (G and J) are also referred to as an IPv6
	node.		node.
	The 6LBR ("A") in the figure is the root of the Global DODAG.		The 6LBR ("A") in the figure is the root of the Global DODAG.
	+------------+		+------------+
	| INTERNET ----------+		| INTERNET ----------+
	| | |		| | |
	skipping to change at page 13, line 42 ¶		skipping to change at page 13, line 42 ¶
	| 6LR | | 6LR | | |		| 6LR | | 6LR | | |
	| | +------ | | |		| | +------ | | |
	+---|---+ | +---|---+ | |		+---|---+ | +---|---+ | |
	| | | | |		| | | | |
	| | +--+ | |		| | +--+ | |
	| | | | |		| | | | |
	| | | | |		| | | | |
	| | | I | J |		| | | I | J |
	F | | G | H | |		F | | G | H | |
	+-----+-+ +-|-----+ +---|--+ +---|---+ +---|---+		+-----+-+ +-|-----+ +---|--+ +---|---+ +---|---+
	| Raf | | ~Raf | | Raf | | Raf | | ~Raf |		| RAL | | RUL | | RAL | | RAL | | RUL |
	| 6LN | | 6LN | | 6LN | | 6LN | | 6LN |		| 6LN | | 6LN | | 6LN | | 6LN | | 6LN |
	+-------+ +-------+ +------+ +-------+ +-------+		+-------+ +-------+ +------+ +-------+ +-------+
	Figure 6: A reference RPL Topology.		Figure 6: A reference RPL Topology.
	5. Use cases		6. Use cases
	In the data plane a combination of RFC6553, RFC6554 and IPv6-in-IPv6		In the data plane a combination of RFC6553, RFC6554 and IPv6-in-IPv6
	encapsulation are going to be analyzed for a number of representative		encapsulation are going to be analyzed for a number of representative
	traffic flows.		traffic flows.
	This document assumes that the LLN is using the no-drop RPI option		This document assumes that the LLN is using the no-drop RPI option
	(0x23).		(0x23).
	The uses cases describe the communication between RPL-aware-nodes,		The use cases describe the communication in the following cases: -
	with the root (6LBR), and with Internet. This document also		Between RPL-aware-nodes with the root (6LBR) - Between RPL-aware-
	describes the communication between nodes acting as leaves that do		nodes with the Internet - Between RUL nodes within the LLN (e.g. see
	not understand RPL (~Raf nodes), but are part of the LLN. (e.g.		Section 7.1.4) - Inside of the LLN when the final destination address
	Section 6.1.4 Flow from not-RPL-aware-leaf to root) This document		resides outside of the LLN (e.g. see Section 7.2.3).
	depicts as well the communication inside of the LLN when it has the
	final destination addressed outside of the LLN e.g. with destination
	to Internet. For example, Section 6.2.3 Flow from not-RPL-aware-leaf
	to Internet
	The uses cases comprise as follow:		The uses cases are as follows:
	Interaction between Leaf and Root:		Interaction between Leaf and Root:
	RPL-aware-leaf(Raf) to root		RAL to root
	root to RPL-aware-leaf(Raf)		root to RAL
	not-RPL-aware-leaf(~Raf) to root		RUL to root
	root to not-RPL-aware-leaf(~Raf)		root to RUL
	Interaction between Leaf and Internet:		Interaction between Leaf and Internet:
	RPL-aware-leaf(Raf) to Internet		RAL to Internet
	Internet to RPL-aware-leaf(Raf)		Internet to RAL
	not-RPL-aware-leaf(~Raf) to Internet		RUL to Internet
	Internet to not-RPL-aware-leaf(~Raf)		Internet to RUL
	Interaction between Leafs:		Interaction between Leafs:
	RPL-aware-leaf(Raf) to RPL-aware-leaf(Raf) (storing and non-		RAL to RAL (storing and non-storing)
	storing)
	RPL-aware-leaf(Raf) to not-RPL-aware-leaf(~Raf) (non-storing)		RAL to RUL (non-storing)
	not-RPL-aware-leaf(~Raf) to RPL-aware-leaf(Raf) (storing and non-
	storing)
	not-RPL-aware-leaf(~Raf) to not-RPL-aware-leaf(~Raf) (non-storing)		RUL to RAL (storing and non-storing)
			RUL to RUL (non-storing)
	This document is consistent with the rule that a Header cannot be		This document is consistent with the rule that a Header cannot be
	inserted or removed on the fly inside an IPv6 packet that is being		inserted or removed on the fly inside an IPv6 packet that is being
	routed. This is a fundamental precept of the IPv6 architecture as		routed. This is a fundamental precept of the IPv6 architecture as
	outlined in [RFC8200]. Extensions headers may not be added or		outlined in [RFC8200].
	removed except by the sender or the receiver.
	As the rank information in the RPI artifact is changed at each hop,		As the rank information in the RPI artifact is changed at each hop,
	it will typically be zero when it arrives at the DODAG root. The		it will typically be zero when it arrives at the DODAG root. The
	DODAG root MUST force it to zero when passing the packet out to the		DODAG root MUST force it to zero when passing the packet out to the
	Internet. The Internet will therefore not see any SenderRank		Internet. The Internet will therefore not see any SenderRank
	information.		information.
	Despite being legal to leave the RPI artifact in place, an		Despite being legal to leave the RPI artifact in place, an
	intermediate router that needs to add an extension header (e.g. RH3		intermediate router that needs to add an extension header (e.g. RH3
	or RPI Option) MUST still encapsulate the packet in an (additional)		or RPI Option) MUST still encapsulate the packet in an (additional)
	skipping to change at page 16, line 8 ¶		skipping to change at page 15, line 50 ¶
	RPI for downward flows in non-storing mode. The exception covered a		RPI for downward flows in non-storing mode. The exception covered a
	very small number of cases, and causes significant interoperability		very small number of cases, and causes significant interoperability
	challenges, yet costed significant code and testing complexity. The		challenges, yet costed significant code and testing complexity. The
	ability to compress the RPI down to three bytes or less removes much		ability to compress the RPI down to three bytes or less removes much
	of the pressure to optimize this any further		of the pressure to optimize this any further
	[I-D.ietf-anima-autonomic-control-plane].		[I-D.ietf-anima-autonomic-control-plane].
	The earlier examples are more extensive to make sure that the process		The earlier examples are more extensive to make sure that the process
	is clear, while later examples are more concise.		is clear, while later examples are more concise.
	6. Storing mode		The uses cases are delineated based on the following requirements:
			The RPI option has to be in every packet that traverses the LLN.
			- Because of (1), packets from the Internet have to be
			encapsulated.
			- A Header cannot be inserted or removed on the fly inside an IPv6
			packet that is being routed.
			- Extension headers may not be added or removed except by the
			sender or the receiver.
			- RPI and RH3 headers may be modified by routers on the path of
			the packet without the need to add and remove an encapsulating
			header.
			- An RH3 or RPI Option can only be removed by an intermediate
			router if it is placed in an encapsulating IPv6 Header, which is
			addressed to the intermediate router.
			- Non-storing mode requires downstream encapsulation by root for
			RH3.
			The uses cases are delineated based on the following assumptions:
			This document assumes that the LLN is using the no-drop RPI option
			(0x23).
			- Each IPv6 node (including Internet routers) obeys [RFC8200]
			8200, so that 0x23 RPI can be safely inserted.
			- All 6LRs obey [RFC8200].
			- The RPI is ignored at the IPv6 dst node (RPL-unaware-leaf).
			- The leaf can be a router 6LR or a host, both indicated as 6LN.
			- Non-constrained uses of RPL are not in scope of this document.
			- Compression is based on [RFC8138].
			- The flow label [RFC6437] is not needed in RPL.
			7. Storing mode
	In storing mode (SM) (fully stateful), the sender can determine if		In storing mode (SM) (fully stateful), the sender can determine if
	the destination is inside the LLN by looking if the destination		the destination is inside the LLN by looking if the destination
	address is matched by the DIO's Prefix Information Option (PIO)		address is matched by the DIO's Prefix Information Option (PIO)
	option.		option.
	The following table (Figure 7) itemizes which headers are needed in		The following table (Figure 7) itemizes which headers are needed in
	each of the following scenarios. It indicates if the IPv6-in-IPv6		each of the following scenarios. It indicates if the IPv6-in-IPv6
	header that is added, must be addressed to the final destination (the		header that is added, must be addressed to the final destination (the
	Raf node that is the target(tgt)), to the "root" or if a hop-by-hop		RAL node that is the target(tgt)), to the "root" or if a hop-by-hop
	header must be added (indicated by "hop").		header must be added (indicated by "hop"). In the hop-by-hop basis,
			the destination address for the next hop is the link-layer address of
			the next hop.
	In cases where no IPv6-in-IPv6 header is needed, the column states as		In cases where no IPv6-in-IPv6 header is needed, the column states as
	"No". If the IPv6-in-IPv6 header is needed is a "must".		"No". If the IPv6-in-IPv6 header is needed is a "must".
	In all cases the RPI headers are needed, since it identifies		In all cases the RPI headers are needed, since it identifies
	inconsistencies (loops) in the routing topology. In all cases the		inconsistencies (loops) in the routing topology. In all cases the
	RH3 is not needed because it is not used in storing mode.		RH3 is not needed because it is not used in storing mode.
	In each case, 6LR_i is the intermediate router from source to		In each case, 6LR_i are the intermediate routers from source to
	destination. "1 <= i <= n", n is the number of routers (6LR) that		destination. "1 <= i <= n", n is the number of routers (6LR) that
	the packet goes through from source (6LN) to destination.		the packet goes through from source (6LN) to destination.
	The leaf can be a router 6LR or a host, both indicated as 6LN. The		The leaf can be a router 6LR or a host, both indicated as 6LN. The
	root refers to the 6LBR (see Figure 6).		root refers to the 6LBR (see Figure 6).
	+---------------------+--------------+------------+------------------+		+---------------------+--------------+------------+------------------+
	| Interaction between | Use Case |IPv6-in-IPv6| IPv6-in-IPv6 dst |		| Interaction between | Use Case |IPv6-in-IPv6| IPv6-in-IPv6 dst |
	+---------------------+--------------+------------+------------------+		+---------------------+--------------+------------+------------------+
	| | Raf to root | No | No |		| | RAL to root | No | No |
	+ +--------------+------------+------------------+		+ +--------------+------------+------------------+
	| Leaf - Root | root to Raf | No | No |		| Leaf - Root | root to RAL | No | No |
	+ +--------------+------------+------------------+		+ +--------------+------------+------------------+
	| | root to ~Raf | No | No |		| | root to RUL | No | No |
	+ +--------------+------------+------------------+		+ +--------------+------------+------------------+
	| | ~Raf to root | must | root |		| | RUL to root | must | root |
	+---------------------+--------------+------------+------------------+		+---------------------+--------------+------------+------------------+
	| | Raf to Int | No | No |		| | RAL to Int | No | No |
	+ +--------------+------------+------------------+		+ +--------------+------------+------------------+
	| Leaf - Internet | Int to Raf | must | Raf (tgt) |		| Leaf - Internet | Int to RAL | must | RAL (tgt) |
	+ +--------------+------------+------------------+		+ +--------------+------------+------------------+
	| | ~Raf to Int | must | root |		| | RUL to Int | must | root |
	+ +--------------+------------+------------------+		+ +--------------+------------+------------------+
	| | Int to ~Raf | must | hop |		| | Int to RUL | must | hop |
	+---------------------+--------------+------------+------------------+		+---------------------+--------------+------------+------------------+
	| | Raf to Raf | No | No |		| | RAL to RAL | No | No |
	+ +--------------+------------+------------------+		+ +--------------+------------+------------------+
	| | Raf to ~Raf | No | No |		| | RAL to RUL | No | No |
	+ Leaf - Leaf +--------------+------------+------------------+		+ Leaf - Leaf +--------------+------------+------------------+
	| | ~Raf to Raf | must | Raf (tgt) |		| | RUL to RAL | must | RAL (tgt) |
	+ +--------------+------------+------------------+		+ +--------------+------------+------------------+
	| | ~Raf to ~Raf | must | hop |		| | RUL to RUL | must | hop |
	+---------------------+--------------+------------+------------------+		+---------------------+--------------+------------+------------------+
	Figure 7: Table of IPv6-in-IPv6 encapsulation in Storing mode.		Figure 7: Table of IPv6-in-IPv6 encapsulation in Storing mode.
	6.1. Storing Mode: Interaction between Leaf and Root		7.1. Storing Mode: Interaction between Leaf and Root
	In this section is described the communication flow in storing mode		In this section is described the communication flow in storing mode
	(SM) between,		(SM) between,
	RPL-aware-leaf to root		RAL to root
	root to RPL-aware-leaf		root to RAL
	not-RPL-aware-leaf to root		RUL to root
	root to not-RPL-aware-leaf		root to RUL
	6.1.1. SM: Example of Flow from RPL-aware-leaf to root		7.1.1. SM: Example of Flow from RAL to root
	In storing mode, RFC 6553 (RPI) is used to send RPL Information		In storing mode, RFC 6553 (RPI) is used to send RPL Information
	instanceID and rank information.		instanceID and rank information.
	As stated in Section 16.2 of [RFC6550] a RPL-aware-leaf node does not
	generally issue DIO messages; a leaf node accepts DIO messages from
	upstream. (When the inconsistency in routing occurs, a leaf node
	will generate a DIO with an infinite rank, to fix it). It may issue
	DAO and DIS messages though it generally ignores DAO and DIS
	messages.
	In this case the flow comprises:		In this case the flow comprises:
	RPL-aware-leaf (6LN) --> 6LR_i --> root(6LBR)		RAL (6LN) --> 6LR_i --> root(6LBR)
	For example, a communication flow could be: Node F --> Node D -->		For example, a communication flow could be: Node F --> Node D -->
	Node B --> Node A root(6LBR)		Node B --> Node A root(6LBR)
	As it was mentioned in this document 6LRs, 6LBR are always full-
	fledged RPL routers.
	The 6LN (Node F) inserts the RPI header, and sends the packet to 6LR		The 6LN (Node F) inserts the RPI header, and sends the packet to 6LR
	(Node E) which decrements the rank in RPI and sends the packet up.		(Node E) which decrements the rank in RPI and sends the packet up.
	When the packet arrives at 6LBR (Node A), the RPI is removed and the		When the packet arrives at 6LBR (Node A), the RPI is removed and the
	packet is processed.		packet is processed.
	No IPv6-in-IPv6 header is required.		No IPv6-in-IPv6 header is required.
	The RPI header can be removed by the 6LBR because the packet is		The RPI header can be removed by the 6LBR because the packet is
	addressed to the 6LBR. The 6LN must know that it is communicating		addressed to the 6LBR. The 6LN must know that it is communicating
	with the 6LBR to make use of this scenario. The 6LN can know the		with the 6LBR to make use of this scenario. The 6LN can know the
	skipping to change at page 18, line 47 ¶		skipping to change at page 19, line 37 ¶
	+-------------------+---------+-------+----------+		+-------------------+---------+-------+----------+
	| Header | 6LN src | 6LR_i | 6LBR dst |		| Header | 6LN src | 6LR_i | 6LBR dst |
	+-------------------+---------+-------+----------+		+-------------------+---------+-------+----------+
	| Inserted headers | RPI | -- | -- |		| Inserted headers | RPI | -- | -- |
	| Removed headers | -- | -- | RPI |		| Removed headers | -- | -- | RPI |
	| Re-added headers | -- | -- | -- |		| Re-added headers | -- | -- | -- |
	| Modified headers | -- | RPI | -- |		| Modified headers | -- | RPI | -- |
	| Untouched headers | -- | -- | -- |		| Untouched headers | -- | -- | -- |
	+-------------------+---------+-------+----------+		+-------------------+---------+-------+----------+
	Table 1: Storing mode: Summary of the use of headers from RPL-aware-		Table 1: SM: Summary of the use of headers from RAL to root
	leaf to root
	6.1.2. SM: Example of Flow from root to RPL-aware-leaf		7.1.2. SM: Example of Flow from root to RAL
	In this case the flow comprises:		In this case the flow comprises:
	root (6LBR) --> 6LR_i --> RPL-aware-leaf (6LN)		root (6LBR) --> 6LR_i --> RAL (6LN)
	For example, a communication flow could be: Node A root(6LBR) -->		For example, a communication flow could be: Node A root(6LBR) -->
	Node B --> Node D --> Node F		Node B --> Node D --> Node F
	In this case the 6LBR inserts RPI header and sends the packet down,		In this case the 6LBR inserts RPI header and sends the packet down,
	the 6LR is going to increment the rank in RPI (it examines the		the 6LR is going to increment the rank in RPI (it examines the
	instanceID to identify the right forwarding table), the packet is		instanceID to identify the right forwarding table), the packet is
	processed in the 6LN and the RPI removed.		processed in the 6LN and the RPI removed.
	No IPv6-in-IPv6 header is required.		No IPv6-in-IPv6 header is required.
	skipping to change at page 19, line 33 ¶		skipping to change at page 20, line 19 ¶
	+-------------------+------+-------+------+		+-------------------+------+-------+------+
	| Header | 6LBR | 6LR_i | 6LN |		| Header | 6LBR | 6LR_i | 6LN |
	+-------------------+------+-------+------+		+-------------------+------+-------+------+
	| Inserted headers | RPI | -- | -- |		| Inserted headers | RPI | -- | -- |
	| Removed headers | -- | -- | RPI |		| Removed headers | -- | -- | RPI |
	| Re-added headers | -- | -- | -- |		| Re-added headers | -- | -- | -- |
	| Modified headers | -- | RPI | -- |		| Modified headers | -- | RPI | -- |
	| Untouched headers | -- | -- | -- |		| Untouched headers | -- | -- | -- |
	+-------------------+------+-------+------+		+-------------------+------+-------+------+
	Table 2: Storing mode: Summary of the use of headers from root to		Table 2: SM: Summary of the use of headers from root to RAL
	RPL-aware-leaf
	6.1.3. SM: Example of Flow from root to not-RPL-aware-leaf		7.1.3. SM: Example of Flow from root to RUL
	In this case the flow comprises:		In this case the flow comprises:
	root (6LBR) --> 6LR_i --> not-RPL-aware-leaf (IPv6)		root (6LBR) --> 6LR_i --> RUL (IPv6)
	For example, a communication flow could be: Node A root(6LBR) -->		For example, a communication flow could be: Node A root(6LBR) -->
	Node B --> Node E --> Node G		Node B --> Node E --> Node G
	As the RPI extension can be ignored by the not-RPL-aware leaf, this		As the RPI extension can be ignored by the not-RPL-aware leaf, this
	situation is identical to the previous scenario.		situation is identical to the previous scenario.
	The Table 3 summarizes what headers are needed for this use case.		The Table 3 summarizes what headers are needed for this use case.
	+-------------------+----------+-------+----------------+		+-------------------+----------+-------+----------------+
	| Header | 6LBR src | 6LR_i | IPv6 dst node |		| Header | 6LBR src | 6LR_i | IPv6 dst node |
	+-------------------+----------+-------+----------------+		+-------------------+----------+-------+----------------+
	| Inserted headers | RPI | -- | -- |		| Inserted headers | RPI | -- | -- |
	| Removed headers | -- | -- | -- |		| Removed headers | -- | -- | -- |
	| Re-added headers | -- | -- | -- |		| Re-added headers | -- | -- | -- |
	| Modified headers | -- | RPI | -- |		| Modified headers | -- | RPI | -- |
	| Untouched headers | -- | -- | RPI (Ignored) |		| Untouched headers | -- | -- | RPI (Ignored) |
	+-------------------+----------+-------+----------------+		+-------------------+----------+-------+----------------+
	Table 3: Storing mode: Summary of the use of headers from root to		Table 3: SM: Summary of the use of headers from root to RUL
	not-RPL-aware-leaf
	6.1.4. SM: Example of Flow from not-RPL-aware-leaf to root		7.1.4. SM: Example of Flow from RUL to root
	In this case the flow comprises:		In this case the flow comprises:
	not-RPL-aware-leaf (IPv6) --> 6LR_1 --> 6LR_i --> root (6LBR)		RUL (IPv6) --> 6LR_1 --> 6LR_i --> root (6LBR)
	For example, a communication flow could be: Node G --> Node E -->		For example, a communication flow could be: Node G --> Node E -->
	Node B --> Node A root(6LBR)		Node B --> Node A root(6LBR)
	When the packet arrives from IPv6 node (Node G) to 6LR_1 (Node E),		When the packet arrives from IPv6 node (Node G) to 6LR_1 (Node E),
	the 6LR_1 will insert a RPI header, encapsulated in a IPv6-in-IPv6		the 6LR_1 will insert a RPI header, encapsulated in a IPv6-in-IPv6
	header. The IPv6-in-IPv6 header can be addressed to the next hop		header. The IPv6-in-IPv6 header can be addressed to the next hop
	(Node B), or to the root (Node A). The root removes the header and		(Node B), or to the root (Node A). The root removes the header and
	processes the packet.		processes the packet.
	The Figure 8 shows the table that summarizes what headers are needed		The Figure 8 shows the table that summarizes what headers are needed
	for this use case. In the figure, IP6-IP6 refers to IPv6-in-IPv6.		for this use case. [1] refers the case where the IPv6-in-IPv6 header
			is addressed to the next hop (Node B). [2] refers the case where the
			IPv6-in-IPv6 header is addressed to the root (Node A).
	+-----------+------+--------------+-----------------+------------------+		+-----------+------+--------------+-----------------+------------------+
	| Header | IPv6 | 6LR_1 | 6LR_i | 6LBR dst |		| Header | IPv6 | 6LR_1 | 6LR_i | 6LBR dst |
	| | src | | | |		| | src | | | |
	| | node | | | |		| | node | | | |
	+-----------+------+--------------+-----------------+------------------+		+-----------+------+--------------+-----------------+------------------+
	| Inserted | -- | IP6-IP6(RPI) | IP6-IP6(RPI)[1] | -- |		| Inserted | -- | IP6-IP6(RPI) | IP6-IP6(RPI)[1] | -- |
	| headers | | | | |		| headers | | | | |
	+-----------+------+--------------+-----------------+------------------+		+-----------+------+--------------+-----------------+------------------+
	| Removed | -- | -- | -- |IP6-IP6(RPI)[1][2]|		| Removed | -- | -- | -- |IP6-IP6(RPI)[1][2]|
	skipping to change at page 21, line 26 ¶		skipping to change at page 21, line 39 ¶
	| Re-added | -- | -- | IP6-IP6(RPI)[1] | -- |		| Re-added | -- | -- | IP6-IP6(RPI)[1] | -- |
	| headers | | | | |		| headers | | | | |
	+-----------+------+--------------+-----------------+------------------+		+-----------+------+--------------+-----------------+------------------+
	| Modified | -- | -- | IP6-IP6(RPI)[2] | -- |		| Modified | -- | -- | IP6-IP6(RPI)[2] | -- |
	| headers | | | | |		| headers | | | | |
	+-----------+------+--------------+-----------------+------------------+		+-----------+------+--------------+-----------------+------------------+
	| Untouched | -- | -- | -- | -- |		| Untouched | -- | -- | -- | -- |
	| headers | | | | |		| headers | | | | |
	+-----------+------+--------------+-----------------+------------------+		+-----------+------+--------------+-----------------+------------------+
	Figure 8: Storing mode: Summary of the use of headers from not-RPL-		Figure 8: SM: Summary of the use of headers from RUL to root.
	aware-leaf to root. [1] Case where the IPv6-in-IPv6 header is
	addressed to the next hop (Node B). [2] Case where the IPv6-in-IPv6
	header is addressed to the root (Node A).
	6.2. Storing Mode: Interaction between Leaf and Internet.		7.2. SM: Interaction between Leaf and Internet.
	In this section is described the communication flow in storing mode		In this section is described the communication flow in storing mode
	(SM) between,		(SM) between,
	RPL-aware-leaf to Internet		RAL to Internet
	Internet to RPL-aware-leaf
	not-RPL-aware-leaf to Internet		Internet to RAL
	Internet to not-RPL-aware-leaf		RUL to Internet
			Internet to RUL
	6.2.1. SM: Example of Flow from RPL-aware-leaf to Internet		7.2.1. SM: Example of Flow from RAL to Internet
	RPL information from RFC 6553 may go out to Internet as it will be		RPL information from RFC 6553 may go out to Internet as it will be
	ignored by nodes which have not been configured to be RPI aware.		ignored by nodes which have not been configured to be RPI aware.
	In this case the flow comprises:		In this case the flow comprises:
	RPL-aware-leaf (6LN) --> 6LR_i --> root (6LBR) --> Internet		RAL (6LN) --> 6LR_i --> root (6LBR) --> Internet
	For example, the communication flow could be: Node F --> Node D -->		For example, the communication flow could be: Node F --> Node D -->
	Node B --> Node A root(6LBR) --> Internet		Node B --> Node A root(6LBR) --> Internet
	No IPv6-in-IPv6 header is required.		No IPv6-in-IPv6 header is required.
	Note: In this use case it is used a node as leaf, but this use case		Note: In this use case it is used a node as leaf, but this use case
	can be also applicable to any RPL-node type (e.g. 6LR)		can be also applicable to any RPL-aware-node type (e.g. 6LR)
	The Table 4 summarizes what headers are needed for this use case.		The Table 4 summarizes what headers are needed for this use case.
	+-------------------+---------+-------+------+----------------+		+-------------------+---------+-------+------+----------------+
	| Header | 6LN src | 6LR_i | 6LBR | Internet dst |		| Header | 6LN src | 6LR_i | 6LBR | Internet dst |
	+-------------------+---------+-------+------+----------------+		+-------------------+---------+-------+------+----------------+
	| Inserted headers | RPI | -- | -- | -- |		| Inserted headers | RPI | -- | -- | -- |
	| Removed headers | -- | -- | -- | -- |		| Removed headers | -- | -- | -- | -- |
	| Re-added headers | -- | -- | -- | -- |		| Re-added headers | -- | -- | -- | -- |
	| Modified headers | -- | RPI | -- | -- |		| Modified headers | -- | RPI | -- | -- |
	| Untouched headers | -- | -- | RPI | RPI (Ignored) |		| Untouched headers | -- | -- | RPI | RPI (Ignored) |
	+-------------------+---------+-------+------+----------------+		+-------------------+---------+-------+------+----------------+
	Table 4: Storing mode: Summary of the use of headers from RPL-aware-		Table 4: SM: Summary of the use of headers from RAL to Internet
	leaf to Internet
	6.2.2. SM: Example of Flow from Internet to RPL-aware-leaf		7.2.2. SM: Example of Flow from Internet to RAL
	In this case the flow comprises:		In this case the flow comprises:
	Internet --> root (6LBR) --> 6LR_i --> RPL-aware-leaf (6LN)		Internet --> root (6LBR) --> 6LR_i --> RAL (6LN)
	For example, a communication flow could be: Internet --> Node A		For example, a communication flow could be: Internet --> Node A
	root(6LBR) --> Node B --> Node D --> Node F		root(6LBR) --> Node B --> Node D --> Node F
	When the packet arrives from Internet to 6LBR the RPI header is added		When the packet arrives from Internet to 6LBR the RPI header is added
	in a outer IPv6-in-IPv6 header (with the IPv6-in-IPv6 destination		in a outer IPv6-in-IPv6 header (with the IPv6-in-IPv6 destination
	address set to the 6LR) and sent to 6LR, which modifies the rank in		address set to the 6LR) and sent to 6LR, which modifies the rank in
	the RPI. When the packet arrives at 6LN the RPI header is removed		the RPI. When the packet arrives at 6LN the RPI header is removed
	and the packet processed.		and the packet processed.
	The Figure 9 shows the table that summarizes what headers are needed		The Figure 9 shows the table that summarizes what headers are needed
	for this use case. In the figure, IP6-IP6 refers to IPv6-in-IPv6.		for this use case.
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	| Header | Internet | 6LBR | 6LR_i | 6LN dst |		| Header | Internet | 6LBR | 6LR_i | 6LN dst |
	| | src | | | |		| | src | | | |
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	| Inserted | -- | IP6-IP6(RPI) | -- | -- |		| Inserted | -- | IP6-IP6(RPI) | -- | -- |
	| headers | | | | |		| headers | | | | |
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	| Removed | -- | -- | -- | IP6-IP6(RPI) |		| Removed | -- | -- | -- | IP6-IP6(RPI) |
	| headers | | | | |		| headers | | | | |
	skipping to change at page 23, line 25 ¶		skipping to change at page 23, line 28 ¶
	| Re-added | -- | -- | -- | -- |		| Re-added | -- | -- | -- | -- |
	| headers | | | | |		| headers | | | | |
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	| Modified | -- | -- | IP6-IP6(RPI) | -- |		| Modified | -- | -- | IP6-IP6(RPI) | -- |
	| headers | | | | |		| headers | | | | |
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	| Untouched | -- | -- | -- | -- |		| Untouched | -- | -- | -- | -- |
	| headers | | | | |		| headers | | | | |
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	Figure 9: Storing mode: Summary of the use of headers from Internet		Figure 9: SM: Summary of the use of headers from Internet to RAL.
	to RPL-aware-leaf.
	6.2.3. SM: Example of Flow from not-RPL-aware-leaf to Internet		7.2.3. SM: Example of Flow from RUL to Internet
	In this case the flow comprises:		In this case the flow comprises:
	not-RPL-aware-leaf (IPv6) --> 6LR_1 --> 6LR_i -->root (6LBR) -->		RUL (IPv6) --> 6LR_1 --> 6LR_i -->root (6LBR) --> Internet
	Internet
	For example, a communication flow could be: Node G --> Node E -->		For example, a communication flow could be: Node G --> Node E -->
	Node B --> Node A root(6LBR) --> Internet		Node B --> Node A root(6LBR) --> Internet
	The 6LR_1 (i=1) node will add an IPv6-in-IPv6(RPI) header addressed		The 6LR_1 (i=1) node will add an IPv6-in-IPv6(RPI) header addressed
	either to the root, or hop-by-hop such that the root can remove the		either to the root, or hop-by-hop such that the root can remove the
	RPI header before passing upwards. The IPv6-in-IPv6 addressed to the		RPI header before passing upwards. The IPv6-in-IPv6 addressed to the
	root cause less processing overhead. On the other hand, with hop-by-		root cause less processing overhead. On the other hand, with hop-by-
	hop the intermediate routers can check the routing tables for a		hop the intermediate routers can check the routing tables for a
	better routing path, thus it could be more efficient and faster.		better routing path, thus it could be more efficient and faster.
	Implementation should decide which approach to take.		Implementation should decide which approach to take.
	The originating node will ideally leave the IPv6 flow label as zero		The originating node will ideally leave the IPv6 flow label as zero
	so that the packet can be better compressed through the LLN. The		so that the packet can be better compressed through the LLN. The
	6LBR will set the flow label of the packet to a non-zero value when		6LBR will set the flow label of the packet to a non-zero value when
	sending to the Internet.		sending to the Internet, for details check [RFC6437].
	The Figure 10 shows the table that summarizes what headers are needed		The Figure 10 shows the table that summarizes what headers are needed
	for this use case. In the figure, IP6-IP6 refers to IPv6-in-IPv6.		for this use case.
	+---------+-------+------------+--------------+-------------+--------+		+---------+-------+------------+--------------+-------------+--------+
	| Header | IPv6 | 6LR_1 | 6LR_i | 6LBR |Internet|		| Header | IPv6 | 6LR_1 | 6LR_i | 6LBR |Internet|
	| | src | | [i=2,...,n] | | dst |		| | src | | [i=2,...,n] | | dst |
	| | node | | | | |		| | node | | | | |
	+---------+-------+------------+--------------+-------------+--------+		+---------+-------+------------+--------------+-------------+--------+
	| Inserted| -- |IP6-IP6(RPI)| IP6-IP6(RPI) | -- | -- |		| Inserted| -- |IP6-IP6(RPI)| IP6-IP6(RPI) | -- | -- |
	| headers | | | [2] | | |		| headers | | | [2] | | |
	+---------+-------+------------+--------------+-------------+--------+		+---------+-------+------------+--------------+-------------+--------+
	| Removed | -- | -- | IP6-IP6(RPI) | IP6-IP6(RPI)| -- |		| Removed | -- | -- | IP6-IP6(RPI) | IP6-IP6(RPI)| -- |
	skipping to change at page 24, line 26 ¶		skipping to change at page 24, line 29 ¶
	| Re-added| -- | -- | -- | -- | -- |		| Re-added| -- | -- | -- | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	+---------+-------+------------+--------------+-------------+--------+		+---------+-------+------------+--------------+-------------+--------+
	| Modified| -- | -- | IP6-IP6(RPI) | -- | -- |		| Modified| -- | -- | IP6-IP6(RPI) | -- | -- |
	| headers | | | [1] | | |		| headers | | | [1] | | |
	+---------+-------+------------+--------------+-------------+--------+		+---------+-------+------------+--------------+-------------+--------+
	|Untouched| -- | -- | -- | -- | -- |		|Untouched| -- | -- | -- | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	+---------+-------+------------+--------------+-------------+--------+		+---------+-------+------------+--------------+-------------+--------+
	Figure 10: Storing mode: Summary of the use of headers from not-RPL-		Figure 10: SM: Summary of the use of headers from RUL to Internet.
	aware-leaf to Internet. [1] Case when packet is addressed to the		[1] Case when packet is addressed to the root. [2] Case when the
	root. [2] Case when the packet is addressed hop-by-hop.		packet is addressed hop-by-hop.
	6.2.4. SM: Example of Flow from Internet to not-RPL-aware-leaf.		7.2.4. SM: Example of Flow from Internet to RUL.
	In this case the flow comprises:		In this case the flow comprises:
	Internet --> root (6LBR) --> 6LR_i --> not-RPL-aware-leaf (IPv6)		Internet --> root (6LBR) --> 6LR_i --> RUL (IPv6)
	For example, a communication flow could be: Internet --> Node A		For example, a communication flow could be: Internet --> Node A
	root(6LBR) --> Node B --> Node E --> Node G		root(6LBR) --> Node B --> Node E --> Node G
	The 6LBR will have to add an RPI header within an IPv6-in-IPv6		The 6LBR will have to add an RPI header within an IPv6-in-IPv6
	header. The IPv6-in-IPv6 is addressed hop-by-hop.		header. The IPv6-in-IPv6 is addressed hop-by-hop.
	The final node should be able to remove one or more IPv6-in-IPv6		The final node should be able to remove one or more IPv6-in-IPv6
	headers which are all addressed to it. The final node does not		headers which are all addressed to it. The final node does not
	process the RPI, the node ignores the RPI. Furhter details about		process the RPI, the node ignores the RPI. Furhter details about
	this are mentioned in [I-D.thubert-roll-unaware-leaves], which		this are mentioned in [I-D.thubert-roll-unaware-leaves], which
	specifies RPL routing for a 6LN acting as a plain host and not aware		specifies RPL routing for a 6LN acting as a plain host and not aware
	of RPL.		of RPL.
	The 6LBR may set the flow label on the inner IPv6-in-IPv6 header to		The 6LBR may set the flow label on the inner IPv6-in-IPv6 header to
	zero in order to aid in compression.		zero in order to aid in compression [RFC8138][RFC6437].
	The Figure 11 shows the table that summarizes what headers are needed		The Figure 11 shows the table that summarizes what headers are needed
	for this use case. In the figure, IP6-IP6 refers to IPv6-in-IPv6.		for this use case.
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	| Header | Internet | 6LBR | 6LR_i |IPv6 dst node |		| Header | Internet | 6LBR | 6LR_i |IPv6 dst node |
	| | src | | | |		| | src | | | |
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	| Inserted | -- | IP6-IP6(RPI) | -- | -- |		| Inserted | -- | IP6-IP6(RPI) | -- | -- |
	| headers | | | | |		| headers | | | | |
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	| Removed | -- | -- | | IP6-IP6(RPI)|		| Removed | -- | -- | | IP6-IP6(RPI)|
	| headers | | | | RPI Ignored |		| headers | | | | RPI Ignored |
	skipping to change at page 25, line 28 ¶		skipping to change at page 25, line 31 ¶
	| Re-added | -- | -- | -- | -- |		| Re-added | -- | -- | -- | -- |
	| headers | | | | |		| headers | | | | |
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	| Modified | -- | -- | IP6-IP6(RPI) | -- |		| Modified | -- | -- | IP6-IP6(RPI) | -- |
	| headers | | | | |		| headers | | | | |
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	| Untouched | -- | -- | -- | -- |		| Untouched | -- | -- | -- | -- |
	| headers | | | | |		| headers | | | | |
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	Figure 11: Storing mode: Summary of the use of headers from Internet		Figure 11: SM: Summary of the use of headers from Internet to RUL.
	to not-RPL-aware-leaf.
	6.3. Storing Mode: Interaction between Leaf and Leaf		7.3. SM: Interaction between Leaf and Leaf
	In this section is described the communication flow in storing mode		In this section is described the communication flow in storing mode
	(SM) between,		(SM) between,
	RPL-aware-leaf to RPL-aware-leaf		RAL to RAL
	RPL-aware-leaf to not-RPL-aware-leaf		RAL to RUL
	not-RPL-aware-leaf to RPL-aware-leaf		RUL to RAL
	not-RPL-aware-leaf to not-RPL-aware-leaf		RUL to RUL
	6.3.1. SM: Example of Flow from RPL-aware-leaf to RPL-aware-leaf		7.3.1. SM: Example of Flow from RAL to RAL
	In [RFC6550] RPL allows a simple one-hop optimization for both		In [RFC6550] RPL allows a simple one-hop optimization for both
	storing and non-storing networks. A node may send a packet destined		storing and non-storing networks. A node may send a packet destined
	to a one-hop neighbor directly to that node. See section 9 in		to a one-hop neighbor directly to that node. See section 9 in
	[RFC6550].		[RFC6550].
	When the nodes are not directly connected, then in storing mode, the		When the nodes are not directly connected, then in storing mode, the
	flow comprises:		flow comprises:
	6LN --> 6LR_ia --> common parent (6LR_x) --> 6LR_id --> 6LN		6LN --> 6LR_ia --> common parent (6LR_x) --> 6LR_id --> 6LN
	For example, a communication flow could be: Node F --> Node D -->		For example, a communication flow could be: Node F --> Node D -->
	Node B --> Node E --> Node H		Node B --> Node E --> Node H
	6LR_ia (Node D) is the intermediate router from source to the common		6LR_ia (Node D) are the intermediate routers from source to the
	parent (6LR_x) (Node B) In this case, "1 <= ia <= n", n is the number		common parent (6LR_x) (Node B) In this case, 1 <= ia <= n, n is the
	of routers (6LR) that the packet goes through from 6LN (Node F) to		number of routers (6LR) that the packet goes through from 6LN (Node
	the common parent (6LR_x).		F) to the common parent (6LR_x).
	6LR_id (Node E) is the intermediate router from the common parent		6LR_id (Node E) are the intermediate routers from the common parent
	(6LR_x) (Node B) to destination 6LN (Node H). In this case, "1 <= id		(6LR_x) (Node B) to destination 6LN (Node H). In this case, 1 <= id
	<= m", m is the number of routers (6LR) that the packet goes through		<= m, m is the number of routers (6LR) that the packet goes through
	from the common parent (6LR_x) to destination 6LN.		from the common parent (6LR_x) to destination 6LN.
	It is assumed that the two nodes are in the same RPL Domain (that		It is assumed that the two nodes are in the same RPL Domain (that
	they share the same DODAG root). At the common parent (Node B), the		they share the same DODAG root). At the common parent (Node B), the
	direction of RPI is changed (from increasing to decreasing the rank).		direction of RPI is changed (from increasing to decreasing the rank).
	While the 6LR nodes will update the RPI, no node needs to add or		While the 6LR nodes will update the RPI, no node needs to add or
	remove the RPI, so no IPv6-in-IPv6 headers are necessary.		remove the RPI, so no IPv6-in-IPv6 headers are necessary.
	The Table 5 summarizes what headers are needed for this use case.		The Table 5 summarizes what headers are needed for this use case.
	skipping to change at page 26, line 45 ¶		skipping to change at page 26, line 48 ¶
	| Removed | -- | -- | -- | -- | RPI |		| Removed | -- | -- | -- | -- | RPI |
	| headers | | | | | |		| headers | | | | | |
	| Re-added | -- | -- | -- | -- | -- |		| Re-added | -- | -- | -- | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	| Modified | -- | RPI | RPI | RPI | -- |		| Modified | -- | RPI | RPI | RPI | -- |
	| headers | | | | | |		| headers | | | | | |
	| Untouched | -- | -- | -- | -- | -- |		| Untouched | -- | -- | -- | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	+---------------+--------+--------+---------------+--------+--------+		+---------------+--------+--------+---------------+--------+--------+
	Table 5: Storing mode: Summary of the use of headers for RPL-aware-		Table 5: SM: Summary of the use of headers for RAL to RAL
	leaf to RPL-aware-leaf
	6.3.2. SM: Example of Flow from RPL-aware-leaf to not-RPL-aware-leaf		7.3.2. SM: Example of Flow from RAL to RUL
	In this case the flow comprises:		In this case the flow comprises:
	6LN --> 6LR_ia --> common parent (6LR_x) --> 6LR_id --> not-RPL-aware		6LN --> 6LR_ia --> common parent (6LR_x) --> 6LR_id --> not-RPL-aware
	6LN (IPv6)		6LN (IPv6)
	For example, a communication flow could be: Node F --> Node D -->		For example, a communication flow could be: Node F --> Node D -->
	Node B --> Node E --> Node G		Node B --> Node E --> Node G
	6LR_ia is the intermediate router from source (6LN) to the common		6LR_ia are the intermediate routers from source (6LN) to the common
	parent (6LR_x) In this case, "1 <= ia <= n", n is the number of		parent (6LR_x) In this case, 1 <= ia <= n, n is the number of routers
	routers (6LR) that the packet goes through from 6LN to the common		(6LR) that the packet goes through from 6LN to the common parent
	parent (6LR_x).		(6LR_x).
	6LR_id (Node E) is the intermediate router from the common parent		6LR_id (Node E) are the intermediate routers from the common parent
	(6LR_x) (Node B) to destination not-RPL-aware 6LN (IPv6) (Node G).		(6LR_x) (Node B) to destination not-RPL-aware 6LN (IPv6) (Node G).
	In this case, "1 <= id <= m", m is the number of routers (6LR) that		In this case, 1 <= id <= m, m is the number of routers (6LR) that the
	the packet goes through from the common parent (6LR_x) to destination		packet goes through from the common parent (6LR_x) to destination
	6LN.		6LN.
	This situation is identical to the previous situation Section 6.3.1		This situation is identical to the previous situation Section 7.3.1
	The Table 6 summarizes what headers are needed for this use case.		The Table 6 summarizes what headers are needed for this use case.
	+-----------+------+--------+---------------+--------+--------------+		+-----------+------+--------+---------------+--------+--------------+
	| Header | 6LN | 6LR_ia | 6LR_x(common | 6LR_id | IPv6 dst |		| Header | 6LN | 6LR_ia | 6LR_x(common | 6LR_id | IPv6 dst |
	| | src | | parent) | | node |		| | src | | parent) | | node |
	+-----------+------+--------+---------------+--------+--------------+		+-----------+------+--------+---------------+--------+--------------+
	| Inserted | RPI | -- | -- | -- | -- |		| Inserted | RPI | -- | -- | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	| Removed | -- | -- | -- | -- | -- |		| Removed | -- | -- | -- | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	| Re-added | -- | -- | -- | -- | -- |		| Re-added | -- | -- | -- | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	| Modified | -- | RPI | RPI | RPI | -- |		| Modified | -- | RPI | RPI | RPI | -- |
	| headers | | | | | |		| headers | | | | | |
	| Untouched | -- | -- | -- | -- | RPI(Ignored) |		| Untouched | -- | -- | -- | -- | RPI(Ignored) |
	| headers | | | | | |		| headers | | | | | |
	+-----------+------+--------+---------------+--------+--------------+		+-----------+------+--------+---------------+--------+--------------+
	Table 6: Storing mode: Summary of the use of headers for RPL-aware-		Table 6: SM: Summary of the use of headers for RAL to RUL
	leaf to not-RPL-aware-leaf
	6.3.3. SM: Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf		7.3.3. SM: Example of Flow from RUL to RAL
	In this case the flow comprises:		In this case the flow comprises:
	not-RPL-aware 6LN (IPv6) --> 6LR_ia --> common parent (6LR_x) -->		not-RPL-aware 6LN (IPv6) --> 6LR_ia --> common parent (6LR_x) -->
	6LR_id --> 6LN		6LR_id --> 6LN
	For example, a communication flow could be: Node G --> Node E -->		For example, a communication flow could be: Node G --> Node E -->
	Node B --> Node D --> Node F		Node B --> Node D --> Node F
	6LR_ia (Node E) is the intermediate router from source (not-RPL-aware		6LR_ia (Node E) are the intermediate routers from source (not-RPL-
	6LN (IPv6)) (Node G) to the common parent (6LR_x) (Node B). In this		aware 6LN (IPv6)) (Node G) to the common parent (6LR_x) (Node B). In
	case, "1 <= ia <= n", n is the number of routers (6LR) that the		this case, 1 <= ia <= n, n is the number of routers (6LR) that the
	packet ges through from source to the common parent.		packet ges through from source to the common parent.
	6LR_id (Node D) is the intermediate router from the common parent		6LR_id (Node D) are the intermediate routers from the common parent
	(6LR_x) (Node B) to destination 6LN (Node F). In this case, "1 <= id		(6LR_x) (Node B) to destination 6LN (Node F). In this case, 1 <= id
	<= m", m is the number of routers (6LR) that the packet goes through		<= m, m is the number of routers (6LR) that the packet goes through
	from the common parent (6LR_x) to destination 6LN.		from the common parent (6LR_x) to destination 6LN.
	The 6LR_ia (ia=1) (Node E) receives the packet from the the IPv6 node		The 6LR_ia (ia=1) (Node E) receives the packet from the the IPv6 node
	(Node G) and inserts and the RPI header encapsulated in IPv6-in-IPv6		(Node G) and inserts and the RPI header encapsulated in IPv6-in-IPv6
	header. The IPv6-in-IPv6 header is addressed to the destination 6LN		header. The IPv6-in-IPv6 header is addressed to the destination 6LN
	(Node F).		(Node F).
	The Figure 12 shows the table that summarizes what headers are needed		The Figure 12 shows the table that summarizes what headers are needed
	for this use case. In the figure, IP6-IP6 refers to IPv6-in-IPv6.		for this use case.
	+---------+-----+------------+-------------+-------------+------------+		+---------+-----+------------+-------------+-------------+------------+
	| Header |IPv6 | 6LR_ia | Common | 6LR_id | 6LN |		| Header |IPv6 | 6LR_ia | Common | 6LR_id | 6LN |
	| |src | | Parent | | dst |		| |src | | Parent | | dst |
	| |node | | (6LRx) | | |		| |node | | (6LRx) | | |
	+---------+-----+------------+-------------+-------------+------------+		+---------+-----+------------+-------------+-------------+------------+
	| Inserted| -- |IP6-IP6(RPI)| -- | -- | -- |		| Inserted| -- |IP6-IP6(RPI)| -- | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	+---------+-----+------------+-------------+-------------+------------+		+---------+-----+------------+-------------+-------------+------------+
	| Removed | -- | -- | -- | -- |IP6-IP6(RPI)|		| Removed | -- | -- | -- | -- |IP6-IP6(RPI)|
	skipping to change at page 28, line 46 ¶		skipping to change at page 28, line 50 ¶
	| Re-added| -- | -- | -- | -- | -- |		| Re-added| -- | -- | -- | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	+---------+-----+------------+-------------+-------------+------------+		+---------+-----+------------+-------------+-------------+------------+
	| Modified| -- | -- |IP6-IP6(RPI) |IP6-IP6(RPI) | -- |		| Modified| -- | -- |IP6-IP6(RPI) |IP6-IP6(RPI) | -- |
	| headers | | | | | |		| headers | | | | | |
	+---------+-----+------------+-------------+-------------+------------+		+---------+-----+------------+-------------+-------------+------------+
	|Untouched| -- | -- | -- | -- | -- |		|Untouched| -- | -- | -- | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	+---------+-----+------------+-------------+-------------+------------+		+---------+-----+------------+-------------+-------------+------------+
	Figure 12: Storing mode: Summary of the use of headers from not-RPL-		Figure 12: SM: Summary of the use of headers from RUL to RAL.
	aware-leaf to RPL-aware-leaf.
	6.3.4. SM: Example of Flow from not-RPL-aware-leaf to not-RPL-aware-		7.3.4. SM: Example of Flow from RUL to RUL
	leaf
	In this case the flow comprises:		In this case the flow comprises:
	not-RPL-aware 6LN (IPv6 src)--> 6LR_1--> 6LR_ia --> 6LBR --> 6LR_id		not-RPL-aware 6LN (IPv6 src)--> 6LR_1--> 6LR_ia --> 6LBR --> 6LR_id
	--> not-RPL-aware 6LN (IPv6 dst)		--> not-RPL-aware 6LN (IPv6 dst)
	For example, a communication flow could be: Node G --> Node E -->		For example, a communication flow could be: Node G --> Node E -->
	Node B --> Node A (root) --> Node C --> Node J		Node B --> Node A (root) --> Node C --> Node J
	Internal nodes 6LR_ia (e.g: Node E or Node B) is the intermediate		Internal nodes 6LR_ia (e.g: Node E or Node B) is the intermediate
	router from the not-RPL-aware source (Node G) to the root (6LBR)		router from the not-RPL-aware source (Node G) to the root (6LBR)
	(Node A). In this case, "1 < ia <= n", n is the number of routers		(Node A). In this case, "1 < ia <= n", n is the number of routers
	(6LR) that the packet goes through from IPv6 src to the root.		(6LR) that the packet goes through from IPv6 src to the root.
	6LR_id (C) is the intermediate router from the root (Node A) to the		6LR_id (Node C) are the intermediate routers from the root (Node A)
	destination Node J. In this case, "1 <= id <= m", m is the number of		to the destination Node J. In this case, 1 <= id <= m, m is the
	routers (6LR) that the packet goes through from the root to		number of routers (6LR) that the packet goes through from the root to
	destination (IPv6 dst).		destination (IPv6 dst).
	The RPI is ignored at the IPv6 dst node.		The RPI is ignored at the IPv6 dst node.
	The 6LR_1 (Node E) receives the packet from the the IPv6 node (Node		The 6LR_1 (Node E) receives the packet from the the IPv6 node (Node
	G) and inserts the RPI header (RPI), encapsulated in an IPv6-in-IPv6		G) and inserts the RPI header (RPI), encapsulated in an IPv6-in-IPv6
	header. The IPv6-in-IPv6 header is addressed hop-by-hop.		header. The IPv6-in-IPv6 header is addressed hop-by-hop.
	The Figure 13 shows the table that summarizes what headers are needed		The Figure 13 shows the table that summarizes what headers are needed
	for this use case. In the figure, IP6-IP6 refers to IPv6-in-IPv6.		for this use case.
	+---------+------+-------+-------+---------+-------+-------+		+---------+------+-------+-------+---------+-------+-------+
	| Header | IPv6 | 6LR_1 | 6LR_ia| 6LBR |6LR_id | IPv6 |		| Header | IPv6 | 6LR_1 | 6LR_ia| 6LBR |6LR_id | IPv6 |
	| | src | | | | | dst |		| | src | | | | | dst |
	| | node | | | | | node |		| | node | | | | | node |
	+---------+------+-------+-------+---------+-------+-------+		+---------+------+-------+-------+---------+-------+-------+
	| Inserted| -- |IP6-IP6| -- | | -- | -- |		| Inserted| -- |IP6-IP6| -- | | -- | -- |
	| headers | | (RPI )| | | | |		| headers | | (RPI )| | | | |
	| | | | | | | |		| | | | | | | |
	+---------+------+-------+-------+---------+-------+-------+		+---------+------+-------+-------+---------+-------+-------+
	skipping to change at page 30, line 30 ¶		skipping to change at page 30, line 30 ¶
	| headers | | | | | | |		| headers | | | | | | |
	+---------+------+-------+-------+---------+-------+-------+		+---------+------+-------+-------+---------+-------+-------+
	| Modified| -- | -- |IP6-IP6| IP6-IP6 |IP6-IP6| -- |		| Modified| -- | -- |IP6-IP6| IP6-IP6 |IP6-IP6| -- |
	| headers | | | (RPI) | (RPI) | (RPI) | |		| headers | | | (RPI) | (RPI) | (RPI) | |
	| | | | | | | |		| | | | | | | |
	+---------+------+-------+-------+---------+-------+-------+		+---------+------+-------+-------+---------+-------+-------+
	|Untouched| -- | -- | -- | -- | -- | -- |		|Untouched| -- | -- | -- | -- | -- | -- |
	| headers | | | | | | |		| headers | | | | | | |
	+---------+------+-------+-------+---------+-------+-------+		+---------+------+-------+-------+---------+-------+-------+
	Figure 13: Storing mode: Summary of the use of headers from not-RPL-		Figure 13: SM: Summary of the use of headers from RUL to RUL
	aware-leaf to not-RPL-aware-leaf
	7. Non Storing mode		8. Non Storing mode
	In Non Storing Mode (Non SM) (fully source routed), the 6LBR (DODAG		In Non Storing Mode (Non-SM) (fully source routed), the 6LBR (DODAG
	root) has complete knowledge about the connectivity of all DODAG		root) has complete knowledge about the connectivity of all DODAG
	nodes, and all traffic flows through the root node. Thus, there is		nodes, and all traffic flows through the root node. Thus, there is
	no need for all nodes to know about the existence of not-RPL aware		no need for all nodes to know about the existence of not-RPL aware
	nodes. Only the 6LBR needs to act if compensation is necessary for		nodes. Only the 6LBR needs to act if compensation is necessary for
	not-RPL aware receivers.		not-RPL aware receivers.
	The following table (Figure 14) summarizes what headers are needed in		The following table (Figure 14) summarizes what headers are needed in
	the following scenarios, and indicates when the RPI, RH3 and IPv6-in-		the following scenarios, and indicates when the RPI, RH3 and IPv6-in-
	IPv6 header are to be inserted. It depicts the target destination		IPv6 header are to be inserted. It depicts the target destination
	address possible (indicated by "Raf"), to a 6LR (parent of a 6LN) or		address possible (indicated by "RAL"), to a 6LR (parent of a 6LN) or
	to the root. In cases where no IPv6-in-IPv6 header is needed, the		to the root. In cases where no IPv6-in-IPv6 header is needed, the
	column states as "No". There is no expectation on RPL that RPI can		column states as "No". There is no expectation on RPL that RPI can
	be omitted, because it is needed for routing, quality of service and		be omitted, because it is needed for routing, quality of service and
	compression. This specification expects that is always a RPI		compression. This specification expects that is always a RPI
	Present.		Present.
	The leaf can be a router 6LR or a host, both indicated as 6LN		The leaf can be a router 6LR or a host, both indicated as 6LN
	(Figure 3). In the Figure the (1) indicates a 6tisch case [RFC8180],		(Figure 3). In the Figure the (1) indicates a 6tisch case [RFC8180],
	where the RPI header may still be needed for the instanceID to be		where the RPI header may still be needed for the instanceID to be
	available for priority/channel selection at each hop.		available for priority/channel selection at each hop.
	+-----------------+--------------+-----+-----+------------+------------+		+-----------------+--------------+-----+-----+------------+------------+
	| Interaction | Use Case | RPI | RH3 |IPv6-in-IPv6|IPv6-in-IPv6|		| Interaction | Use Case | RPI | RH3 |IPv6-in-IPv6|IPv6-in-IPv6|
	| between | | | | | dst |		| between | | | | | dst |
	+-----------------+--------------+-----+-----+------------+------------+		+-----------------+--------------+-----+-----+------------+------------+
	| | Raf to root | Yes | No | No | No |		| | RAL to root | Yes | No | No | No |
	+ +--------------+-----+-----+------------+------------+		+ +--------------+-----+-----+------------+------------+
	| Leaf - Root | root to Raf | Yes | Yes | No | No |		| Leaf - Root | root to RAL | Yes | Yes | No | No |
	+ +--------------+-----+-----+------------+------------+		+ +--------------+-----+-----+------------+------------+
	| | root to ~Raf | Yes | Yes | must | 6LR |		| | root to RUL | Yes | Yes | must | 6LR |
	| | | (1) | | | |		| | | (1) | | | |
	+ +--------------+-----+-----+------------+------------+		+ +--------------+-----+-----+------------+------------+
	| | ~Raf to root | Yes | No | must | root |		| | RUL to root | Yes | No | must | root |
	+-----------------+--------------+-----+-----+------------+------------+		+-----------------+--------------+-----+-----+------------+------------+
	| | Raf to Int | Yes | No | No | No |		| | RAL to Int | Yes | No | No | No |
	+ +--------------+-----+-----+------------+------------+		+ +--------------+-----+-----+------------+------------+
	| Leaf - Internet | Int to Raf | Yes | Yes | must | Raf |		| Leaf - Internet | Int to RAL | Yes | Yes | must | RAL |
	+ +--------------+-----+-----+------------+------------+		+ +--------------+-----+-----+------------+------------+
	| | ~Raf to Int | Yes | No | must | root |		| | RUL to Int | Yes | No | must | root |
	+ +--------------+-----+-----+------------+------------+		+ +--------------+-----+-----+------------+------------+
	| | Int to ~Raf | Yes | Yes | must | 6LR |		| | Int to RUL | Yes | Yes | must | 6LR |
	+-----------------+--------------+-----+-----+------------+------------+		+-----------------+--------------+-----+-----+------------+------------+
	| | Raf to Raf | Yes | Yes | must | root/Raf |		| | RAL to RAL | Yes | Yes | must | root/RAL |
	+ +--------------+-----+-----+------------+------------+		+ +--------------+-----+-----+------------+------------+
	| | Raf to ~Raf | Yes | Yes | must | root/6LR |		| | RAL to RUL | Yes | Yes | must | root/6LR |
	+ Leaf - Leaf +--------------+-----+-----+------------+------------+		+ Leaf - Leaf +--------------+-----+-----+------------+------------+
	| | ~Raf to Raf | Yes | Yes | must | root/Raf |		| | RUL to RAL | Yes | Yes | must | root/RAL |
	+ +--------------+-----+-----+------------+------------+		+ +--------------+-----+-----+------------+------------+
	| | ~Raf to ~Raf | Yes | Yes | must | root/6LR |		| | RUL to RUL | Yes | Yes | must | root/6LR |
	+-----------------+--------------+-----+-----+------------+------------+		+-----------------+--------------+-----+-----+------------+------------+
	Figure 14: Table that shows headers needed in Non-Storing mode: RPI,		Figure 14: Table that shows headers needed in Non-Storing mode: RPI,
	RH3, IPv6-in-IPv6 encapsulation.		RH3, IPv6-in-IPv6 encapsulation.
	7.1. Non-Storing Mode: Interaction between Leaf and Root		8.1. Non-Storing Mode: Interaction between Leaf and Root
	In this section is described the communication flow in Non Storing		In this section is described the communication flow in Non Storing
	Mode (Non-SM) between,		Mode (Non-SM) between,
	RPL-aware-leaf to root		RAL to root
	root to RPL-aware-leaf		root to RAL
	not-RPL-aware-leaf to root		RUL to root
	root to not-RPL-aware-leaf
	7.1.1. Non-SM: Example of Flow from RPL-aware-leaf to root		root to RUL
			8.1.1. Non-SM: Example of Flow from RAL to root
	In non-storing mode the leaf node uses default routing to send		In non-storing mode the leaf node uses default routing to send
	traffic to the root. The RPI header must be included since it		traffic to the root. The RPI header must be included since it
	contains the rank information, which is used to avoid/detect loops.		contains the rank information, which is used to avoid/detect loops.
	RPL-aware-leaf (6LN) --> 6LR_i --> root(6LBR)		RAL (6LN) --> 6LR_i --> root(6LBR)
	For example, a communication flow could be: Node F --> Node D -->		For example, a communication flow could be: Node F --> Node D -->
	Node B --> Node A (root)		Node B --> Node A (root)
	6LR_i is the intermediate router from source to destination. In this		6LR_i are the intermediate routers from source to destination. In
	case, "1 <= i <= n", n is the number of routers (6LR) that the packet		this case, "1 <= i <= n", n is the number of routers (6LR) that the
	goes through from source (6LN) to destination (6LBR).		packet goes through from source (6LN) to destination (6LBR).
	This situation is the same case as storing mode.		This situation is the same case as storing mode.
	The Table 7 summarizes what headers are needed for this use case.		The Table 7 summarizes what headers are needed for this use case.
	+-------------------+---------+-------+----------+		+-------------------+---------+-------+----------+
	| Header | 6LN src | 6LR_i | 6LBR dst |		| Header | 6LN src | 6LR_i | 6LBR dst |
	+-------------------+---------+-------+----------+		+-------------------+---------+-------+----------+
	| Inserted headers | RPI | -- | -- |		| Inserted headers | RPI | -- | -- |
	| Removed headers | -- | -- | RPI |		| Removed headers | -- | -- | RPI |
	| Re-added headers | -- | -- | -- |		| Re-added headers | -- | -- | -- |
	| Modified headers | -- | RPI | -- |		| Modified headers | -- | RPI | -- |
	| Untouched headers | -- | -- | -- |		| Untouched headers | -- | -- | -- |
	+-------------------+---------+-------+----------+		+-------------------+---------+-------+----------+
	Table 7: Non Storing mode: Summary of the use of headers from RPL-		Table 7: Non-SM: Summary of the use of headers from RAL to root
	aware-leaf to root
	7.1.2. Non-SM: Example of Flow from root to RPL-aware-leaf		8.1.2. Non-SM: Example of Flow from root to RAL
	In this case the flow comprises:		In this case the flow comprises:
	root (6LBR) --> 6LR_i --> RPL-aware-leaf (6LN)		root (6LBR) --> 6LR_i --> RAL (6LN)
	For example, a communication flow could be: Node A (root) --> Node B		For example, a communication flow could be: Node A (root) --> Node B
	--> Node D --> Node F		--> Node D --> Node F
	6LR_i is the intermediate router from source to destination. In this		6LR_i are the intermediate routers from source to destination. In
	case, "1 <= i <= n", n is the number of routers (6LR) that the packet		this case, "1 <= i <= n", n is the number of routers (6LR) that the
	goes through from source (6LBR) to destination (6LN).		packet goes through from source (6LBR) to destination (6LN).
	The 6LBR inserts an RH3, and a RPI header. No IPv6-in-IPv6 header is		The 6LBR inserts an RH3, and a RPI header. No IPv6-in-IPv6 header is
	necessary as the traffic originates with an RPL aware node, the 6LBR.		necessary as the traffic originates with an RPL aware node, the 6LBR.
	The destination is known to be RPL-aware because the root knows the		The destination is known to be RPL-aware because the root knows the
	whole topology in non-storing mode.		whole topology in non-storing mode.
	The Table 8 summarizes what headers are needed for this use case.		The Table 8 summarizes what headers are needed for this use case.
	+-------------------+----------+-----------+-----------+		+-------------------+----------+-----------+-----------+
	| Header | 6LBR src | 6LR_i | 6LN dst |		| Header | 6LBR src | 6LR_i | 6LN dst |
	+-------------------+----------+-----------+-----------+		+-------------------+----------+-----------+-----------+
	| Inserted headers | RPI, RH3 | -- | -- |		| Inserted headers | RPI, RH3 | -- | -- |
	| Removed headers | -- | -- | RH3, RPI |		| Removed headers | -- | -- | RH3, RPI |
	| Re-added headers | -- | -- | -- |		| Re-added headers | -- | -- | -- |
	| Modified headers | -- | RPI, RH3 | -- |		| Modified headers | -- | RPI, RH3 | -- |
	| Untouched headers | -- | -- | -- |		| Untouched headers | -- | -- | -- |
	+-------------------+----------+-----------+-----------+		+-------------------+----------+-----------+-----------+
	Table 8: Non Storing mode: Summary of the use of headers from root to		Table 8: Non-SM: Summary of the use of headers from root to RAL
	RPL-aware-leaf
	7.1.3. Non-SM: Example of Flow from root to not-RPL-aware-leaf		8.1.3. Non-SM: Example of Flow from root to RUL
	In this case the flow comprises:		In this case the flow comprises:
	root (6LBR) --> 6LR_i --> not-RPL-aware-leaf (IPv6)		root (6LBR) --> 6LR_i --> RUL (IPv6)
	For example, a communication flow could be: Node A (root) --> Node B		For example, a communication flow could be: Node A (root) --> Node B
	--> Node E --> Node G		--> Node E --> Node G
	6LR_i is the intermediate router from source to destination. In this		6LR_i are the intermediate routers from source to destination. In
	case, "1 <= i <= n", n is the number of routers (6LR) that the packet		this case, "1 <= i <= n", n is the number of routers (6LR) that the
	goes through from source (6LBR) to destination (IPv6).		packet goes through from source (6LBR) to destination (IPv6).
	In 6LBR the RH3 is added, it is modified at each intermediate 6LR		In 6LBR the RH3 is added, it is modified at each intermediate 6LR
	(6LR_1 and so on) and it is fully consumed in the last 6LR (6LR_n),		(6LR_1 and so on) and it is fully consumed in the last 6LR (6LR_n),
	but left there. As the RPI is added, then the IPv6 node which does		but left there. As the RPI is added, then the IPv6 node which does
	not understand the RPI, will ignore it (following RFC8200), thus		not understand the RPI, will ignore it (following RFC8200), thus
	encapsulation is not necessary.		encapsulation is not necessary.
	The Figure 15 depicts the table that summarizes what headers are		The Figure 15 depicts the table that summarizes what headers are
	needed for this use case.		needed for this use case.
	skipping to change at page 34, line 27 ¶		skipping to change at page 34, line 27 ¶
	| headers | | | | |		| headers | | | | |
	+-----------+----------+--------------+----------------+----------+		+-----------+----------+--------------+----------------+----------+
	| Modified | -- | RPI, RH3 | RPI, | -- |		| Modified | -- | RPI, RH3 | RPI, | -- |
	| headers | | | RH3(consumed) | |		| headers | | | RH3(consumed) | |
	+-----------+----------+--------------+----------------+----------+		+-----------+----------+--------------+----------------+----------+
	| Untouched | -- | -- | -- | RPI, RH3 |		| Untouched | -- | -- | -- | RPI, RH3 |
	| headers | | | | (both |		| headers | | | | (both |
	| | | | | ignored) |		| | | | | ignored) |
	+-----------+----------+--------------+----------------+----------+		+-----------+----------+--------------+----------------+----------+
	Figure 15: Non Storing mode: Summary of the use of headers from root		Figure 15: Non-SM: Summary of the use of headers from root to RUL
	to not-RPL-aware-leaf
	7.1.4. Non-SM: Example of Flow from not-RPL-aware-leaf to root		8.1.4. Non-SM: Example of Flow from RUL to root
	In this case the flow comprises:		In this case the flow comprises:
	not-RPL-aware-leaf (IPv6) --> 6LR_1 --> 6LR_i --> root (6LBR)		RUL (IPv6) --> 6LR_1 --> 6LR_i --> root (6LBR)
	For example, a communication flow could be: Node G --> Node E -->		For example, a communication flow could be: Node G --> Node E -->
	Node B --> Node A (root)		Node B --> Node A (root)
	6LR_i is the intermediate router from source to destination. In this		6LR_i are the intermediate routers from source to destination. In
	case, "1 < i <= n", n is the number of routers (6LR) that the packet		this case, "1 < i <= n", n is the number of routers (6LR) that the
	goes through from source (IPv6) to destination (6LBR). For example,		packet goes through from source (IPv6) to destination (6LBR). For
	6LR_1 (i=1) is the router that receives the packets from the IPv6		example, 6LR_1 (i=1) is the router that receives the packets from the
	node.		IPv6 node.
	In this case the RPI is added by the first 6LR (6LR1) (Node E),		In this case the RPI is added by the first 6LR (6LR1) (Node E),
	encapsulated in an IPv6-in-IPv6 header, and is modified in the		encapsulated in an IPv6-in-IPv6 header, and is modified in the
	following 6LRs. The RPI and entire packet is consumed by the root.		following 6LRs. The RPI and entire packet is consumed by the root.
	The Figure 16 shows the table that summarizes what headers are needed		The Figure 16 shows the table that summarizes what headers are needed
	for this use case.		for this use case.
	+---------+----+-----------------+-----------------+-----------------+		+---------+----+-----------------+-----------------+-----------------+
	| Header |IPv6| 6LR_1 | 6LR_i | 6LBR dst |		| Header |IPv6| 6LR_1 | 6LR_i | 6LBR dst |
	skipping to change at page 35, line 26 ¶		skipping to change at page 35, line 26 ¶
	| Re-added| -- | -- | -- | -- |		| Re-added| -- | -- | -- | -- |
	| headers | | | | |		| headers | | | | |
	+---------+----+-----------------+-----------------+-----------------+		+---------+----+-----------------+-----------------+-----------------+
	| Modified| -- | -- |IPv6-in-IPv6(RPI)| -- |		| Modified| -- | -- |IPv6-in-IPv6(RPI)| -- |
	| headers | | | | |		| headers | | | | |
	+---------+----+-----------------+-----------------+-----------------+		+---------+----+-----------------+-----------------+-----------------+
	|Untouched| -- | -- | -- | -- |		|Untouched| -- | -- | -- | -- |
	| headers | | | | |		| headers | | | | |
	+---------+----+-----------------+-----------------+-----------------+		+---------+----+-----------------+-----------------+-----------------+
	Figure 16: Non Storing mode: Summary of the use of headers from not-		Figure 16: Non-SM: Summary of the use of headers from RUL to root
	RPL-aware-leaf to root
	7.2. Non-Storing Mode: Interaction between Leaf and Internet		8.2. Non-Storing Mode: Interaction between Leaf and Internet
	This section will describe the communication flow in Non Storing Mode		This section will describe the communication flow in Non Storing Mode
	(Non-SM) between:		(Non-SM) between:
	RPL-aware-leaf to Internet		RAL to Internet
	Internet to RPL-aware-leaf		Internet to RAL
	not-RPL-aware-leaf to Internet		RUL to Internet
	Internet to not-RPL-aware-leaf		Internet to RUL
	7.2.1. Non-SM: Example of Flow from RPL-aware-leaf to Internet		8.2.1. Non-SM: Example of Flow from RAL to Internet
	In this case the flow comprises:		In this case the flow comprises:
	RPL-aware-leaf (6LN) --> 6LR_i --> root (6LBR) --> Internet		RAL (6LN) --> 6LR_i --> root (6LBR) --> Internet
	For example, a communication flow could be: Node F --> Node D -->		For example, a communication flow could be: Node F --> Node D -->
	Node B --> Node A --> Internet		Node B --> Node A --> Internet
	6LR_i is the intermediate router from source to destination. In this
	case, "1 <= i <= n", n is the number of routers (6LR) that the packet		6LR_i are the intermediate routers from source to destination. In
	goes through from source (6LN) to 6LBR.		this case, "1 <= i <= n", n is the number of routers (6LR) that the
			packet goes through from source (6LN) to 6LBR.
	This case is identical to storing-mode case.		This case is identical to storing-mode case.
	The IPv6 flow label should be set to zero to aid in compression, and		The IPv6 flow label should be set to zero to aid in compression
	the 6LBR will set it to a non-zero value when sending towards the		[RFC8138], and the 6LBR will set it to a non-zero value when sending
	Internet.		towards the Internet [RFC6437].
	The Table 9 summarizes what headers are needed for this use case.		The Table 9 summarizes what headers are needed for this use case.
	+-------------------+---------+-------+------+----------------+		+-------------------+---------+-------+------+----------------+
	| Header | 6LN src | 6LR_i | 6LBR | Internet dst |		| Header | 6LN src | 6LR_i | 6LBR | Internet dst |
	+-------------------+---------+-------+------+----------------+		+-------------------+---------+-------+------+----------------+
	| Inserted headers | RPI | -- | -- | -- |		| Inserted headers | RPI | -- | -- | -- |
	| Removed headers | -- | -- | -- | -- |		| Removed headers | -- | -- | -- | -- |
	| Re-added headers | -- | -- | -- | -- |		| Re-added headers | -- | -- | -- | -- |
	| Modified headers | -- | RPI | -- | -- |		| Modified headers | -- | RPI | -- | -- |
	| Untouched headers | -- | -- | RPI | RPI (Ignored) |		| Untouched headers | -- | -- | RPI | RPI (Ignored) |
	+-------------------+---------+-------+------+----------------+		+-------------------+---------+-------+------+----------------+
	Table 9: Non Storing mode: Summary of the use of headers from RPL-		Table 9: Non-SM: Summary of the use of headers from RAL to Internet
	aware-leaf to Internet
	7.2.2. Non-SM: Example of Flow from Internet to RPL-aware-leaf		8.2.2. Non-SM: Example of Flow from Internet to RAL
	In this case the flow comprises:		In this case the flow comprises:
	Internet --> root (6LBR) --> 6LR_i --> RPL-aware-leaf (6LN)		Internet --> root (6LBR) --> 6LR_i --> RAL (6LN)
	For example, a communication flow could be: Internet --> Node A		For example, a communication flow could be: Internet --> Node A
	(root) --> Node B --> Node D --> Node F		(root) --> Node B --> Node D --> Node F
	6LR_i is the intermediate router from source to destination. In this		6LR_i are the intermediate routers from source to destination. In
	case, "1 <= i <= n", n is the number of routers (6LR) that the packet		this case, "1 <= i <= n", n is the number of routers (6LR) that the
	goes through from 6LBR to destination(6LN).		packet goes through from 6LBR to destination(6LN).
	The 6LBR must add an RH3 header. As the 6LBR will know the path and		The 6LBR must add an RH3 header. As the 6LBR will know the path and
	address of the target node, it can address the IPv6-in-IPv6 header to		address of the target node, it can address the IPv6-in-IPv6 header to
	that node. The 6LBR will zero the flow label upon entry in order to		that node. The 6LBR will zero the flow label upon entry in order to
	aid compression.		aid compression [RFC8138].
	The Table 10 summarizes what headers are needed for this use case.		The Table 10 summarizes what headers are needed for this use case.
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	| Header | Internet | 6LBR | 6LR_i | 6LN src |		| Header | Internet | 6LBR | 6LR_i | 6LN src |
	| | dst | | | |		| | dst | | | |
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	| Inserted | -- | IPv6-in-IPv6 | -- | -- |		| Inserted | -- | IPv6-in-IPv6 | -- | -- |
	| headers | | (RH3,RPI) | | |		| headers | | (RH3,RPI) | | |
	| Removed | -- | -- | -- | IPv6-in-IPv6 |		| Removed | -- | -- | -- | IPv6-in-IPv6 |
	| headers | | | | (RH3,RPI) |		| headers | | | | (RH3,RPI) |
	| Re-added | -- | -- | -- | -- |		| Re-added | -- | -- | -- | -- |
	| headers | | | | |		| headers | | | | |
	| Modified | -- | -- | IPv6-in-IPv6 | -- |		| Modified | -- | -- | IPv6-in-IPv6 | -- |
	| headers | | | (RH3,RPI) | |		| headers | | | (RH3,RPI) | |
	| Untouched | -- | -- | -- | -- |		| Untouched | -- | -- | -- | -- |
	| headers | | | | |		| headers | | | | |
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	Table 10: Non Storing mode: Summary of the use of headers from		Table 10: Non-SM: Summary of the use of headers from Internet to RAL
	Internet to RPL-aware-leaf
	7.2.3. Non-SM: Example of Flow from not-RPL-aware-leaf to Internet		8.2.3. Non-SM: Example of Flow from RUL to Internet
	In this case the flow comprises:		In this case the flow comprises:
	not-RPL-aware-leaf (IPv6) --> 6LR_1 --> 6LR_i -->root (6LBR) -->		RUL (IPv6) --> 6LR_1 --> 6LR_i -->root (6LBR) --> Internet
	Internet
	For example, a communication flow could be: Node G --> Node E -->		For example, a communication flow could be: Node G --> Node E -->
	Node B --> Node A --> Internet		Node B --> Node A --> Internet
	6LR_i is the intermediate router from source to destination. In this		6LR_i are the intermediate routers from source to destination. In
	case, "1 < i <= n", n is the number of routers (6LR) that the packet		this case, "1 < i <= n", n is the number of routers (6LR) that the
	goes through from source(IPv6) to 6LBR. e.g 6LR_1 (i=1).		packet goes through from source(IPv6) to 6LBR. e.g 6LR_1 (i=1).
	In this case the flow label is recommended to be zero in the IPv6		In this case the flow label is recommended to be zero in the IPv6
	node. As RPL headers are added in the IPv6 node packet, the first		node. As RPL headers are added in the IPv6 node packet, the first
	6LR (6LR_1) will add a RPI header inside a new IPv6-in-IPv6 header.		6LR (6LR_1) will add a RPI header inside a new IPv6-in-IPv6 header.
	The IPv6-in-IPv6 header will be addressed to the root. This case is		The IPv6-in-IPv6 header will be addressed to the root. This case is
	identical to the storing-mode case (see Section 6.2.3).		identical to the storing-mode case (see Section 7.2.3).
	The Figure 17 shows the table that summarizes what headers are needed		The Figure 17 shows the table that summarizes what headers are needed
	for this use case. In the figure, IP6-IP6 refers to IPv6-in-IPv6.		for this use case.
	+---------+----+-------------+--------------+--------------+--------+		+---------+----+-------------+--------------+--------------+--------+
	| Header |IPv6| 6LR_1 | 6LR_i | 6LBR |Internet|		| Header |IPv6| 6LR_1 | 6LR_i | 6LBR |Internet|
	| |src | | [i=2,..,n] | | dst |		| |src | | [i=2,..,n] | | dst |
	| |node| | | | |		| |node| | | | |
	+---------+----+-------------+--------------+--------------+--------+		+---------+----+-------------+--------------+--------------+--------+
	| Inserted| -- |IP6-IP6(RPI) | -- | -- | -- |		| Inserted| -- |IP6-IP6(RPI) | -- | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	+---------+----+-------------+--------------+--------------+--------+		+---------+----+-------------+--------------+--------------+--------+
	| Removed | -- | -- | -- | IP6-IP6(RPI) | -- |		| Removed | -- | -- | -- | IP6-IP6(RPI) | -- |
	skipping to change at page 38, line 26 ¶		skipping to change at page 38, line 26 ¶
	| Re-added| -- | -- | -- | -- | -- |		| Re-added| -- | -- | -- | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	+---------+----+-------------+--------------+--------------+--------+		+---------+----+-------------+--------------+--------------+--------+
	| Modified| -- | -- | IP6-IP6(RPI) | -- | -- |		| Modified| -- | -- | IP6-IP6(RPI) | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	+---------+----+-------------+--------------+--------------+--------+		+---------+----+-------------+--------------+--------------+--------+
	|Untouched| -- | -- | -- | -- | -- |		|Untouched| -- | -- | -- | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	+---------+----+-------------+--------------+--------------+--------+		+---------+----+-------------+--------------+--------------+--------+
	Figure 17: Non Storing mode: Summary of the use of headers from not-		Figure 17: Non-SM: Summary of the use of headers from RUL to Internet
	RPL-aware-leaf to Internet
	7.2.4. Non-SM: Example of Flow from Internet to not-RPL-aware-leaf		8.2.4. Non-SM: Example of Flow from Internet to RUL
	In this case the flow comprises:		In this case the flow comprises:
	Internet --> root (6LBR) --> 6LR_i --> not-RPL-aware-leaf (IPv6)		Internet --> root (6LBR) --> 6LR_i --> RUL (IPv6)
	For example, a communication flow could be: Internet --> Node A		For example, a communication flow could be: Internet --> Node A
	(root) --> Node B --> Node E --> Node G		(root) --> Node B --> Node E --> Node G
	6LR_i is the intermediate router from source to destination. In this		6LR_i are the intermediate routers from source to destination. In
	case, "1 < i <= n", n is the number of routers (6LR) that the packet		this case, "1 < i <= n", n is the number of routers (6LR) that the
	goes through from 6LBR to not-RPL-aware-leaf (IPv6).		packet goes through from 6LBR to RUL (IPv6).
	The 6LBR must add an RH3 header inside an IPv6-in-IPv6 header. The		The 6LBR must add an RH3 header inside an IPv6-in-IPv6 header. The
	6LBR will know the path, and will recognize that the final node is		6LBR will know the path, and will recognize that the final node is
	not an RPL capable node as it will have received the connectivity DAO		not an RPL capable node as it will have received the connectivity DAO
	from the nearest 6LR. The 6LBR can therefore make the IPv6-in-IPv6		from the nearest 6LR. The 6LBR can therefore make the IPv6-in-IPv6
	header destination be the last 6LR. The 6LBR will set to zero the		header destination be the last 6LR. The 6LBR will set to zero the
	flow label upon entry in order to aid compression.		flow label upon entry in order to aid compression [RFC8138].
	The Figure 18 shows the table that summarizes what headers are needed		The Figure 18 shows the table that summarizes what headers are needed
	for this use case.		for this use case.
	+---------+--------+-------------+--------------+--------------+-----+		+---------+--------+-------------+--------------+--------------+-----+
	| Header |Internet| 6LBR | 6LR_1 | 6lR_i |IPv6 |		| Header |Internet| 6LBR | 6LR_1 | 6lR_i |IPv6 |
	| | src | | | (i=2,...,n) |dst |		| | src | | | (i=2,...,n) |dst |
	| | | | | |node |		| | | | | |node |
	+---------+--------+-------------+--------------+--------------+-----+		+---------+--------+-------------+--------------+--------------+-----+
	| Inserted| -- | IPv6-in-IPv6| -- | -- | -- |		| Inserted| -- | IPv6-in-IPv6| -- | -- | -- |
	skipping to change at page 39, line 26 ¶		skipping to change at page 39, line 26 ¶
	| Re-added| -- | -- | -- | -- | -- |		| Re-added| -- | -- | -- | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	+---------+--------+-------------+--------------+--------------+-----+		+---------+--------+-------------+--------------+--------------+-----+
	| Modified| -- | -- | IPv6-in-IPv6 | IPv6-in-IPv6 | -- |		| Modified| -- | -- | IPv6-in-IPv6 | IPv6-in-IPv6 | -- |
	| headers | | | (RH3,RPI) | (RH3,RPI) | |		| headers | | | (RH3,RPI) | (RH3,RPI) | |
	+---------+--------+-------------+--------------+--------------+-----+		+---------+--------+-------------+--------------+--------------+-----+
	|Untouched| -- | -- | -- | -- | -- |		|Untouched| -- | -- | -- | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	+---------+--------+-------------+--------------+--------------+-----+		+---------+--------+-------------+--------------+--------------+-----+
	Figure 18: Non-Storing mode: Summary of the use of headers from		Figure 18: Non-SM: Summary of the use of headers from Internet to RUL
	Internet to not-RPL-aware-leaf [1] The last 6LR before the IPv6 node.		[1] The last 6LR before the IPv6 node.
	7.3. Non-Storing Mode: Interaction between Leafs		8.3. Non-SM: Interaction between Leafs
	In this section is described the communication flow in Non Storing		In this section is described the communication flow in Non Storing
	Mode (Non-SM) between,		Mode (Non-SM) between,
	RPL-aware-leaf to RPL-aware-leaf		RAL to RAL
	RPL-aware-leaf to not-RPL-aware-leaf		RAL to RUL
	not-RPL-aware-leaf to RPL-aware-leaf		RUL to RAL
	not-RPL-aware-leaf to not-RPL-aware-leaf		RUL to RUL
	7.3.1. Non-SM: Example of Flow from RPL-aware-leaf to RPL-aware-leaf		8.3.1. Non-SM: Example of Flow from RAL to RAL
	In this case the flow comprises:		In this case the flow comprises:
	6LN src --> 6LR_ia --> root (6LBR) --> 6LR_id --> 6LN dst		6LN src --> 6LR_ia --> root (6LBR) --> 6LR_id --> 6LN dst
	For example, a communication flow could be: Node F --> Node D -->		For example, a communication flow could be: Node F --> Node D -->
	Node B --> Node A (root) --> Node B --> Node E --> Node H		Node B --> Node A (root) --> Node B --> Node E --> Node H
	6LR_ia is the intermediate router from source to the root In this		6LR_ia are the intermediate routers from source to the root In this
	case, "1 <= ia <= n", n is the number of routers (6LR) that the		case, 1 <= ia <= n, n is the number of routers (6LR) that the packet
	packet goes through from 6LN to the root.		goes through from 6LN to the root.
	6LR_id is the intermediate router from the root to the destination.		6LR_id are the intermediate routers from the root to the destination.
	In this case, "1 <= ia <= m", m is the number of the intermediate		In this case, "1 <= ia <= m", m is the number of the intermediate
	routers (6LR).		routers (6LR).
	This case involves only nodes in same RPL Domain. The originating		This case involves only nodes in same RPL Domain. The originating
	node will add a RPI header to the original packet, and send the		node will add a RPI header to the original packet, and send the
	packet upwards.		packet upwards.
	The originating node must put the RPI into an IPv6-in-IPv6 header		The originating node must put the RPI into an IPv6-in-IPv6 header
	addressed to the root, so that the 6LBR can remove that header. If		addressed to the root, so that the 6LBR can remove that header. If
	it does not, then additional resources are wasted on the way down to		it does not, then additional resources are wasted on the way down to
	carry the useless RPI option.		carry the useless RPI option.
	The 6LBR will need to insert an RH3 header, which requires that it		The 6LBR will need to insert an RH3 header, which requires that it
	add an IPv6-in-IPv6 header. It should be able to remove the RPI, as		add an IPv6-in-IPv6 header. It should be able to remove the RPI, as
	it was contained in an IPv6-in-IPv6 header addressed to it.		it was contained in an IPv6-in-IPv6 header addressed to it.
	Otherwise, there may be a RPI header buried inside the inner IP		Otherwise, there may be a RPI header buried inside the inner IP
	header, which should get ignored.		header, which should get ignored.
	Networks that use the RPL P2P extension [RFC6997] are essentially		Networks that use the RPL P2P extension [RFC6997] are essentially
	non-storing DODAGs and fall into this scenario or scenario		non-storing DODAGs and fall into this scenario or scenario
	Section 7.1.2, with the originating node acting as 6LBR.		Section 8.1.2, with the originating node acting as 6LBR.
	The Figure 19 shows the table that summarizes what headers are needed		The Figure 19 shows the table that summarizes what headers are needed
	for this use case.		for this use case.
	+---------+------------+----------+------------+----------+------------+		+---------+------------+----------+------------+----------+------------+
	| Header | 6LN | 6LR_ia | 6LBR | 6LR_id | 6LN |		| Header | 6LN | 6LR_ia | 6LBR | 6LR_id | 6LN |
	| | src | | | | dst |		| | src | | | | dst |
	+---------+------------+----------+------------+----------+------------+		+---------+------------+----------+------------+----------+------------+
	| Inserted|IPv6-in-IPv6| |IPv6-in-IPv6| -- | -- |		| Inserted|IPv6-in-IPv6| |IPv6-in-IPv6| -- | -- |
	| headers | (RPI1) | |(RH3-> 6LN, | | |		| headers | (RPI1) | |(RH3-> 6LN, | | |
	skipping to change at page 41, line 27 ¶		skipping to change at page 41, line 27 ¶
	| Re-added| -- | -- | -- | -- | -- |		| Re-added| -- | -- | -- | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	+---------+------------+----------+------------+----------+------------+		+---------+------------+----------+------------+----------+------------+
	| Modified| -- |IP6-in-IP6| -- |IP6-in-IP6| -- |		| Modified| -- |IP6-in-IP6| -- |IP6-in-IP6| -- |
	| headers | | (RPI1) | | (RPI2) | |		| headers | | (RPI1) | | (RPI2) | |
	+---------+------------+----------+------------+----------+------------+		+---------+------------+----------+------------+----------+------------+
	|Untouched| -- | -- | -- | -- | -- |		|Untouched| -- | -- | -- | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	+---------+------------+----------+------------+----------+------------+		+---------+------------+----------+------------+----------+------------+
	Figure 19: Non Storing mode: Summary of the use of headers for RPL-		Figure 19: Non-SM: Summary of the use of headers for RAL to RAL.
	aware-leaf to RPL-aware-leaf. IP6-in-IP6 refers to IPv6-in-IPv6.		IP6-in-IP6 refers to IPv6-in-IPv6.
	7.3.2. Non-SM: Example of Flow from RPL-aware-leaf to not-RPL-aware-		8.3.2. Non-SM: Example of Flow from RAL to RUL
	leaf
	In this case the flow comprises:		In this case the flow comprises:
	6LN --> 6LR_ia --> root (6LBR) --> 6LR_id --> not-RPL-aware (IPv6)		6LN --> 6LR_ia --> root (6LBR) --> 6LR_id --> not-RPL-aware (IPv6)
	For example, a communication flow could be: Node F --> Node D -->		For example, a communication flow could be: Node F --> Node D -->
	Node B --> Node A (root) --> Node B --> Node E --> Node G		Node B --> Node A (root) --> Node B --> Node E --> Node G
	6LR_ia is the intermediate router from source to the root In this		6LR_ia are the intermediate routers from source to the root In this
	case, "1 <= ia <= n", n is the number of intermediate routers (6LR)		case, 1 <= ia <= n, n is the number of intermediate routers (6LR)
	6LR_id is the intermediate router from the root to the destination.		6LR_id are the intermediate routers from the root to the destination.
	In this case, "1 <= ia <= m", m is the number of the intermediate		In this case, "1 <= ia <= m", m is the number of the intermediate
	routers (6LRs).		routers (6LRs).
	As in the previous case, the 6LN will insert a RPI (RPI_1) header		As in the previous case, the 6LN will insert a RPI (RPI_1) header
	which must be in an IPv6-in-IPv6 header addressed to the root so that		which must be in an IPv6-in-IPv6 header addressed to the root so that
	the 6LBR can remove this RPI. The 6LBR will then insert an RH3		the 6LBR can remove this RPI. The 6LBR will then insert an RH3
	inside a new IPv6-in-IPv6 header addressed to the 6LR_id.		inside a new IPv6-in-IPv6 header addressed to the 6LR_id.
	The Figure 20 shows the table that summarizes what headers are needed		The Figure 20 shows the table that summarizes what headers are needed
	for this use case. In the figure, IP6-IP6 refers to IPv6-in-IPv6.		for this use case.
	+-----------+---------+---------+---------+---------+---------+------+		+-----------+---------+---------+---------+---------+---------+------+
	| Header | 6LN | 6LR_ia | 6LBR | 6LR_id | 6LR_m | IPv6 |		| Header | 6LN | 6LR_ia | 6LBR | 6LR_id | 6LR_m | IPv6 |
	| | src | | | | | dst |		| | src | | | | | dst |
	| | | | | | | node |		| | | | | | | node |
	+-----------+---------+---------+---------+---------+---------+------+		+-----------+---------+---------+---------+---------+---------+------+
	| Inserted | IP6-IP6 | | IP6-IP6 | -- | -- | -- |		| Inserted | IP6-IP6 | | IP6-IP6 | -- | -- | -- |
	| headers | (RPI1) | | (RH3, | | | |		| headers | (RPI1) | | (RH3, | | | |
	| | | | RPI2) | | | |		| | | | RPI2) | | | |
	+-----------+---------+---------+---------+---------+---------+------+		+-----------+---------+---------+---------+---------+---------+------+
	skipping to change at page 42, line 32 ¶		skipping to change at page 42, line 29 ¶
	| headers | | | | | | |		| headers | | | | | | |
	+-----------+---------+---------+---------+---------+---------+------+		+-----------+---------+---------+---------+---------+---------+------+
	| Modified | -- | IP6-IP6 | -- | IP6-IP6 | | -- |		| Modified | -- | IP6-IP6 | -- | IP6-IP6 | | -- |
	| headers | | (RPI1) | | (RH3, | | |		| headers | | (RPI1) | | (RH3, | | |
	| | | | | RPI2) | | |		| | | | | RPI2) | | |
	+-----------+---------+---------+---------+---------+---------+------+		+-----------+---------+---------+---------+---------+---------+------+
	| Untouched | -- | -- | -- | -- | -- | -- |		| Untouched | -- | -- | -- | -- | -- | -- |
	| headers | | | | | | |		| headers | | | | | | |
	+-----------+---------+---------+---------+---------+---------+------+		+-----------+---------+---------+---------+---------+---------+------+
	Figure 20: Non Storing mode: Summary of the use of headers from RPL-		Figure 20: Non-SM: Summary of the use of headers from RAL to RUL.
	aware-leaf to not-RPL-aware-leaf.
	7.3.3. Non-SM: Example of Flow from not-RPL-aware-leaf to RPL-aware-		8.3.3. Non-SM: Example of Flow from RUL to RAL
	leaf
	In this case the flow comprises:		In this case the flow comprises:
	not-RPL-aware 6LN (IPv6) --> 6LR_1 --> 6LR_ia --> root (6LBR) -->		not-RPL-aware 6LN (IPv6) --> 6LR_1 --> 6LR_ia --> root (6LBR) -->
	6LR_id --> 6LN		6LR_id --> 6LN
	For example, a communication flow could be: Node G --> Node E -->		For example, a communication flow could be: Node G --> Node E -->
	Node B --> Node A (root) --> Node B --> Node E --> Node H		Node B --> Node A (root) --> Node B --> Node E --> Node H
	6LR_ia is the intermediate router from source to the root. In this		6LR_ia are the intermediate routers from source to the root. In this
	case, "1 <= ia <= n", n is the number of intermediate routers (6LR)		case, 1 <= ia <= n, n is the number of intermediate routers (6LR)
	6LR_id is the intermediate router from the root to the destination.		6LR_id are the intermediate routers from the root to the destination.
	In this case, "1 <= ia <= m", m is the number of the intermediate		In this case, "1 <= ia <= m", m is the number of the intermediate
	routers (6LR).		routers (6LR).
	This scenario is mostly identical to the previous one. The RPI is		This scenario is mostly identical to the previous one. The RPI is
	added by the first 6LR (6LR_1) inside an IPv6-in-IPv6 header		added by the first 6LR (6LR_1) inside an IPv6-in-IPv6 header
	addressed to the root. The 6LBR will remove this RPI, and add it's		addressed to the root. The 6LBR will remove this RPI, and add it's
	own IPv6-in-IPv6 header containing an RH3 header and an RPI (RPI_2).		own IPv6-in-IPv6 header containing an RH3 header and an RPI (RPI_2).
	The Figure 21 shows the table that summarizes what headers are needed		The Figure 21 shows the table that summarizes what headers are needed
	for this use case. In the figure, IP6-IP6 refers to IPv6-in-IPv6.		for this use case.
	+-----------+------+---------+---------+---------+---------+---------+		+-----------+------+---------+---------+---------+---------+---------+
	| Header | IPv6 | 6LR_1 | 6LR_ia | 6LBR | 6LR_id | 6LN |		| Header | IPv6 | 6LR_1 | 6LR_ia | 6LBR | 6LR_id | 6LN |
	| | src | | | | | dst |		| | src | | | | | dst |
	| | node | | | | | |		| | node | | | | | |
	+-----------+------+---------+---------+---------+---------+---------+		+-----------+------+---------+---------+---------+---------+---------+
	| Inserted | -- | IP6-IP6 | -- | IP6-IP6 | -- | -- |		| Inserted | -- | IP6-IP6 | -- | IP6-IP6 | -- | -- |
	| headers | | (RPI1) | | (RH3, | | |		| headers | | (RPI1) | | (RH3, | | |
	| | | | | RPI2) | | |		| | | | | RPI2) | | |
	+-----------+------+---------+---------+---------+---------+---------+		+-----------+------+---------+---------+---------+---------+---------+
	skipping to change at page 43, line 37 ¶		skipping to change at page 43, line 32 ¶
	| headers | | | | | | |		| headers | | | | | | |
	+-----------+------+---------+---------+---------+---------+---------+		+-----------+------+---------+---------+---------+---------+---------+
	| Modified | -- | | IP6-IP6 | -- | IP6-IP6 | -- |		| Modified | -- | | IP6-IP6 | -- | IP6-IP6 | -- |
	| headers | | | (RPI1) | | (RH3, | |		| headers | | | (RPI1) | | (RH3, | |
	| | | | | | RPI2) | |		| | | | | | RPI2) | |
	+-----------+------+---------+---------+---------+---------+---------+		+-----------+------+---------+---------+---------+---------+---------+
	| Untouched | -- | | -- | -- | -- | -- |		| Untouched | -- | | -- | -- | -- | -- |
	| headers | | | | | | |		| headers | | | | | | |
	+-----------+------+---------+---------+---------+---------+---------+		+-----------+------+---------+---------+---------+---------+---------+
	Figure 21: Non Storing mode: Summary of the use of headers from not-		Figure 21: Non-SM: Summary of the use of headers from RUL to RAL.
	RPL-aware-leaf to RPL-aware-leaf.
	7.3.4. Non-SM: Example of Flow from not-RPL-aware-leaf to not-RPL-		8.3.4. Non-SM: Example of Flow from RUL to RUL
	aware-leaf
	In this case the flow comprises:		In this case the flow comprises:
	not-RPL-aware 6LN (IPv6 src) --> 6LR_1 --> 6LR_ia --> root (6LBR) -->		not-RPL-aware 6LN (IPv6 src) --> 6LR_1 --> 6LR_ia --> root (6LBR) -->
	6LR_id --> not-RPL-aware (IPv6 dst)		6LR_id --> not-RPL-aware (IPv6 dst)
	For example, a communication flow could be: Node G --> Node E -->		For example, a communication flow could be: Node G --> Node E -->
	Node B --> Node A (root) --> Node C --> Node J		Node B --> Node A (root) --> Node C --> Node J
	6LR_ia is the intermediate router from source to the root. In this		6LR_ia are the intermediate routers from source to the root. In this
	case, "1 <= ia <= n", n is the number of intermediate routers (6LR)		case, 1 <= ia <= n, n is the number of intermediate routers (6LR)
	6LR_id is the intermediate router from the root to the destination.
			6LR_id are the intermediate routers from the root to the destination.
	In this case, "1 <= ia <= m", m is the number of the intermediate		In this case, "1 <= ia <= m", m is the number of the intermediate
	routers (6LR).		routers (6LR).
	This scenario is the combination of the previous two cases.		This scenario is the combination of the previous two cases.
	The Figure 22 shows the table that summarizes what headers are needed		The Figure 22 shows the table that summarizes what headers are needed
	for this use case. In the figure, IP6-IP6 refers to IPv6-in-IPv6.		for this use case.
	+---------+------+-------+-------+---------+-------+---------+------+		+---------+------+-------+-------+---------+-------+---------+------+
	| Header | IPv6 | 6LR_1 | 6LR_ia| 6LBR |6LR_id | 6LR_m | IPv6 |		| Header | IPv6 | 6LR_1 | 6LR_ia| 6LBR |6LR_id | 6LR_m | IPv6 |
	| | src | | | | | | dst |		| | src | | | | | | dst |
	| | node | | | | | | node |		| | node | | | | | | node |
	+---------+------+-------+-------+---------+-------+---------+------+		+---------+------+-------+-------+---------+-------+---------+------+
	| Inserted| -- |IP6-IP6| -- | IP6-IP6 | -- | -- | -- |		| Inserted| -- |IP6-IP6| -- | IP6-IP6 | -- | -- | -- |
	| headers | | (RPI1)| | (RH3, | | | |		| headers | | (RPI1)| | (RH3, | | | |
	| | | | | RPI2) | | | |		| | | | | RPI2) | | | |
	+---------+------+-------+-------+---------+-------+---------+------+		+---------+------+-------+-------+---------+-------+---------+------+
	skipping to change at page 44, line 37 ¶		skipping to change at page 44, line 32 ¶
	| headers | | | | | | | |		| headers | | | | | | | |
	+---------+------+-------+-------+---------+-------+---------+------+		+---------+------+-------+-------+---------+-------+---------+------+
	| Modified| -- | -- |IP6-IP6| -- |IP6-IP6| -- | -- |		| Modified| -- | -- |IP6-IP6| -- |IP6-IP6| -- | -- |
	| headers | | | (RPI1)| | (RH3, | | |		| headers | | | (RPI1)| | (RH3, | | |
	| | | | | | RPI2)| | |		| | | | | | RPI2)| | |
	+---------+------+-------+-------+---------+-------+---------+------+		+---------+------+-------+-------+---------+-------+---------+------+
	|Untouched| -- | -- | -- | -- | -- | -- | -- |		|Untouched| -- | -- | -- | -- | -- | -- | -- |
	| headers | | | | | | | |		| headers | | | | | | | |
	+---------+------+-------+-------+---------+-------+---------+------+		+---------+------+-------+-------+---------+-------+---------+------+
	Figure 22: Non Storing mode: Summary of the use of headers from not-		Figure 22: Non-SM: Summary of the use of headers from RUL to RUL
	RPL-aware-leaf to not-RPL-aware-leaf
	8. Operational Considerations of supporting not-RPL-aware-leaves		9. Operational Considerations of supporting not-RPL-aware-leaves
	Roughly half of the situations described in this document involve		Roughly half of the situations described in this document involve
	leaf ("host") nodes that do not speak RPL. These nodes fall into two		leaf ("host") nodes that do not speak RPL. These nodes fall into two
	further categories: ones that drop a packet that have RPI or RH3		further categories: ones that drop a packet that have RPI or RH3
	headers, and ones that continue to process a packet that has RPI and/		headers, and ones that continue to process a packet that has RPI and/
	or RH3 headers.		or RH3 headers.
	[RFC8200] provides for new rules that suggest that nodes that have		[RFC8200] provides for new rules that suggest that nodes that have
	not been configured (explicitly) to examine Hop-by-Hop headers,		not been configured (explicitly) to examine Hop-by-Hop headers,
	should ignore those headers, and continue processing the packet.		should ignore those headers, and continue processing the packet.
	skipping to change at page 45, line 23 ¶		skipping to change at page 45, line 16 ¶
	case, in the process of removing the IPv6-in-IPv6 header, the		case, in the process of removing the IPv6-in-IPv6 header, the
	artifacts can also be removed.		artifacts can also be removed.
	The above case occurs whenever traffic originates from the outside		The above case occurs whenever traffic originates from the outside
	the LLN (the "Internet" cases above), and non-storing mode is used.		the LLN (the "Internet" cases above), and non-storing mode is used.
	In non-storing mode, the RPL root knows the exact topology (as it		In non-storing mode, the RPL root knows the exact topology (as it
	must be create the RH3 header), and therefore knows what the 6LR		must be create the RH3 header), and therefore knows what the 6LR
	prior to the leaf. For example, in Figure 5, node E is the 6LR prior		prior to the leaf. For example, in Figure 5, node E is the 6LR prior
	to the leaf node G, or node C is the 6LR prior to the leaf node J.		to the leaf node G, or node C is the 6LR prior to the leaf node J.
	Traffic originating from the RPL root (such as when the data		traffic originating from the RPL root (such as when the data
	collection system is co-located on the RPL root), does not require an		collection system is co-located on the RPL root), does not require an
	IPv6-in-IPv6 header (in either mode), as the packet is originating at		IPv6-in-IPv6 header (in either mode), as the packet is originating at
	the root, and the root can insert the RPI and RH3 headers directly		the root, and the root can insert the RPI and RH3 headers directly
	into the packet, as it is formed. Such a packet is slightly smaller,		into the packet, as it is formed. Such a packet is slightly smaller,
	but only can be sent to nodes (whether RPL aware or not), that will		but only can be sent to nodes (whether RPL aware or not), that will
	tolerate the RPL artifacts.		tolerate the RPL artifacts.
	An operator that finds itself with a lot of traffic from the RPL root		An operator that finds itself with a lot of traffic from the RPL root
	to RPL-not-aware-leaves, will have to do IPv6-in-IPv6 encapsulation		to RPL-not-aware-leaves, will have to do IPv6-in-IPv6 encapsulation
	if the leaf is not tolerant of the RPL artifacts. Such an operator		if the leaf is not tolerant of the RPL artifacts. Such an operator
	could otherwise omit this unnecessary header if it was certain of the		could otherwise omit this unnecessary header if it was certain of the
	properties of the leaf.		properties of the leaf.
	As storing mode can not know the final path of the traffic,		As storing mode can not know the final path of the traffic,
	intolerant (that drop packets with RPL artifacts) leaf nodes can not		intolerant (that drop packets with RPL artifacts) leaf nodes can not
	be supported.		be supported.
	9. Operational considerations of introducing 0x23		10. Operational considerations of introducing 0x23
	This section describes the operational considerations of introducing		This section describes the operational considerations of introducing
	the new RPI value of 0x23.		the new RPI value of 0x23.
	During bootstrapping the node gets the DIO with the information of		During bootstrapping the node gets the DIO with the information of
	RPL Option Type, indicating the new RPI in the DODAG Configuration		RPL Option Type, indicating the new RPI in the DODAG Configuration
	Option Flag. The DODAG root is in charge to configure the current		Option Flag. The DODAG root is in charge to configure the current
	network to the new value, through DIO messages and when all the nodes		network to the new value, through DIO messages and when all the nodes
	are set with the new value. The DODAG should change to a new DODAG		are set with the new value. The DODAG should change to a new DODAG
	version. In case of rebooting, the node does not remember the RPL		version. In case of rebooting, the node does not remember the RPL
	skipping to change at page 46, line 27 ¶		skipping to change at page 46, line 21 ¶
	then it abruptly change to 0x23. This options allows to send packets		then it abruptly change to 0x23. This options allows to send packets
	to not-RPL nodes, which should ignore the option and continue		to not-RPL nodes, which should ignore the option and continue
	processing the packets.		processing the packets.
	In case that a node join to a network that only process 0x63, it		In case that a node join to a network that only process 0x63, it
	would produce a flag day as was mentioned previously. Indicating the		would produce a flag day as was mentioned previously. Indicating the
	new RPI in the DODAG Configuration Option Flag is a way to avoid the		new RPI in the DODAG Configuration Option Flag is a way to avoid the
	flag day in a network. It is recommended that a network process both		flag day in a network. It is recommended that a network process both
	options to enable interoperability.		options to enable interoperability.
	10. IANA Considerations		11. IANA Considerations
	This document updates the registration made in [RFC6553] Destination		This document updates the registration made in [RFC6553] Destination
	Options and Hop-by-Hop Options registry from 0x63 to 0x23 as shown in		Options and Hop-by-Hop Options registry from 0x63 to 0x23 as shown in
	Figure 23.		Figure 23.
	+-------+-------------------+------------------------+---------- -+		+-------+-------------------+------------------------+---------- -+
	| Hex | Binary Value | Description | Reference |		| Hex | Binary Value | Description | Reference |
	+ Value +-------------------+ + +		+ Value +-------------------+ + +
	| | act | chg | rest | | |		| | act | chg | rest | | |
	+-------+-----+-----+-------+------------------------+------------+		+-------+-----+-----+-------+------------------------+------------+
	skipping to change at page 47, line 14 ¶		skipping to change at page 47, line 5 ¶
	+------------+-----------------+---------------+		+------------+-----------------+---------------+
	| Bit number | Description | Reference |		| Bit number | Description | Reference |
	+------------+-----------------+---------------+		+------------+-----------------+---------------+
	| 3 | RPI 0x23 enable | This document |		| 3 | RPI 0x23 enable | This document |
	+------------+-----------------+---------------+		+------------+-----------------+---------------+
	Figure 24: DODAG Configuration Option Flag to indicate the RPI-flag-		Figure 24: DODAG Configuration Option Flag to indicate the RPI-flag-
	day.		day.
	11. Security Considerations		12. Security Considerations
	The security considerations covered in [RFC6553] and [RFC6554] apply		The security considerations covered in [RFC6553] and [RFC6554] apply
	when the packets are in the RPL Domain.		when the packets are in the RPL Domain.
	The IPv6-in-IPv6 mechanism described in this document is much more		The IPv6-in-IPv6 mechanism described in this document is much more
	limited than the general mechanism described in [RFC2473]. The		limited than the general mechanism described in [RFC2473]. The
	willingness of each node in the LLN to decapsulate packets and		willingness of each node in the LLN to decapsulate packets and
	forward them could be exploited by nodes to disguise the origin of an		forward them could be exploited by nodes to disguise the origin of an
	attack.		attack.
	While a typical LLN may be a very poor origin for attack traffic (as		While a typical LLN may be a very poor origin for attack traffic (as
	the networks tend to be very slow, and the nodes often have very low		the networks tend to be very slow, and the nodes often have very low
	duty cycles) given enough nodes, they could still have a significant		duty cycles) given enough nodes, they could still have a significant
	impact, particularly if the target of the attack is targeting another		impact, particularly if attack is targeting another LLN.
	LLN. Additionally, some uses of RPL involve large backbone ISP scale		Additionally, some uses of RPL involve large backbone ISP scale
	equipment [I-D.ietf-anima-autonomic-control-plane], which may be		equipment [I-D.ietf-anima-autonomic-control-plane], which may be
	equipped with multiple 100Gb/s interfaces.		equipped with multiple 100Gb/s interfaces.
	Blocking or careful filtering of IPv6-in-IPv6 traffic entering the		Blocking or careful filtering of IPv6-in-IPv6 traffic entering the
	LLN as described above will make sure that any attack that is mounted		LLN as described above will make sure that any attack that is mounted
	must originate from compromised nodes within the LLN. The use of		must originate from compromised nodes within the LLN. The use of
	BCP38 [BCP38] filtering at the RPL root on egress traffic will both		BCP38 [BCP38] filtering at the RPL root on egress traffic will both
	alert the operator to the existence of the attack, as well as drop		alert the operator to the existence of the attack, as well as drop
	the attack traffic. As the RPL network is typically numbered from a		the attack traffic. As the RPL network is typically numbered from a
	single prefix, which is itself assigned by RPL, BCP38 filtering		single prefix, which is itself assigned by RPL, BCP38 filtering
	skipping to change at page 48, line 16 ¶		skipping to change at page 48, line 4 ¶
	only be by a node within the LLN on another node within the LLN.		only be by a node within the LLN on another node within the LLN.
	Such an attack could, of course, be done directly. An attack of this		Such an attack could, of course, be done directly. An attack of this
	kind is meaningful only if the source addresses are either fake or if		kind is meaningful only if the source addresses are either fake or if
	the point is to amplify return traffic. Such an attack, could also		the point is to amplify return traffic. Such an attack, could also
	be done without the use of IPv6-in-IPv6 headers using forged source		be done without the use of IPv6-in-IPv6 headers using forged source
	addresses. If the attack requires bi-directional communication, then		addresses. If the attack requires bi-directional communication, then
	IPv6-in-IPv6 provides no advantages.		IPv6-in-IPv6 provides no advantages.
	Whenever IPv6-in-IPv6 headers are being proposed, there is a concern		Whenever IPv6-in-IPv6 headers are being proposed, there is a concern
	about creating security issues. In the security section of		about creating security issues. In the security section of
	[RFC2473], it was suggested that tunnel entry and exit points can be		[RFC2473], it was suggested that tunnel entry and exit points can be
	secured, via "Use IPsec". This recommendation is not practical for		secured, via "Use IPsec". This recommendation is not practical for
	RPL networks. [RFC5406] goes into some detail on what additional		RPL networks. [RFC5406] goes into some detail on what additional
	details would be needed in order to "Use IPsec". Use of ESP would		details would be needed in order to "Use IPsec". Use of ESP would
	prevent RFC8183 compression (compression must occur before		prevent RFC8183 compression (compression must occur before
	encryption), and RFC8183 compression is lossy in a way that prevents		encryption), and RFC8183 compression is lossy in a way that prevents
	use of AH. These are minor issues. The major issue is how to		use of AH. These are minor issues. The major issue is how to
	establish trust enough such that IKEv2 could be used. This would		establish trust enough such that IKEv2 could be used. This would
	require a system of certificates to be present in every single node,		require a system of certificates to be present in every single node,
	including any Internet nodes that might need to communicate with the		including any Internet nodes that might need to communicate with the
	LLN. Thus, "Use IPsec" requires a global PKI in the general case.		LLN. Thus, "Use IPsec" requires a global PKI in the general case.
	More significantly, the use of IPsec tunnels to protect the IPv6-in-		More significantly, the use of IPsec tunnels to protect the IPv6-in-
	IPv6 headers would in the general case scale with the square of the		IPv6 headers would in the general case scale with the square of the
	number of nodes. This is a lot of resource for a constrained nodes		number of nodes. This is a lot of resource for a constrained nodes
	on a constrained network. In the end, the IPsec tunnels would be		on a constrained network. In the end, the IPsec tunnels would be
	providing only BCP38-like origin authentication! Just doing BCP38		providing only BCP38-like origin authentication! That is, IPsec
			provides a transitive guarantee to the tunnel exit point that the
			tunnel entry point did BCP38 on traffic going in. Just doing BCP38
	origin filtering at the entry and exit of the LLN provides a similar		origin filtering at the entry and exit of the LLN provides a similar
	level amount of security without all the scaling and trust problems		level amount of security without all the scaling and trust problems
	of using IPsec as RFC2473 suggested. IPsec is not recommended.		of using IPsec as RFC2473 suggested. IPsec is not recommended.
	An LLN with hostile nodes within it would not be protected against		An LLN with hostile nodes within it would not be protected against
	impersonation with the LLN by entry/exit filtering.		impersonation with the LLN by entry/exit filtering.
	The RH3 header usage described here can be abused in equivalent ways		The RH3 header usage described here can be abused in equivalent ways
	(to disguise the origin of traffic and attack other nodes) with an		(to disguise the origin of traffic and attack other nodes) with an
	IPv6-in-IPv6 header to add the needed RH3 header. As such, the		IPv6-in-IPv6 header to add the needed RH3 header. As such, the
	skipping to change at page 50, line 24 ¶		skipping to change at page 50, line 15 ¶
	directions.		directions.
	Note: there are some situations where a prefix will spread across		Note: there are some situations where a prefix will spread across
	multiple LLNs via mechanisms such as the one described in		multiple LLNs via mechanisms such as the one described in
	[I-D.ietf-6lo-backbone-router]. In this case the BCP38 filtering		[I-D.ietf-6lo-backbone-router]. In this case the BCP38 filtering
	needs to take this into account, either by exchanging detailed		needs to take this into account, either by exchanging detailed
	routing information on each LLN, or by moving the BCP38 filtering		routing information on each LLN, or by moving the BCP38 filtering
	further towards the Internet, so that the details of the multiple		further towards the Internet, so that the details of the multiple
	LLNs do not matter.		LLNs do not matter.
	12. Acknowledgments		13. Acknowledgments
	This work is done thanks to the grant by the Stand.ICT project.		This work is done thanks to the grant by the Stand.ICT project.
	A special BIG thanks to C. M. Heard for the help with the		A special BIG thanks to C. M. Heard for the help with the
	Section 3. Much of the redaction in that section is based on his		Section 4. Much of the redaction in that section is based on his
	comments.		comments.
	Additionally, the authors would like to acknowledge the review,		Additionally, the authors would like to acknowledge the review,
	feedback, and comments of (alphabetical order): Robert Cragie, Simon		feedback, and comments of (alphabetical order): Robert Cragie, Simon
	Duquennoy, Ralph Droms, Cenk Guendogan, Rahul Jadhav, Matthias		Duquennoy, Ralph Droms, Cenk Guendogan, Rahul Jadhav, Matthias
	Kovatsch, Peter van der Stok, Xavier Vilajosana and Thomas Watteyne.		Kovatsch, Peter van der Stok, Xavier Vilajosana and Thomas Watteyne.
	13. References		14. References
	13.1. Normative References		14.1. Normative References
	[BCP38] Ferguson, P. and D. Senie, "Network Ingress Filtering:		[BCP38] Ferguson, P. and D. Senie, "Network Ingress Filtering:
	Defeating Denial of Service Attacks which employ IP Source		Defeating Denial of Service Attacks which employ IP Source
	Address Spoofing", BCP 38, RFC 2827, DOI 10.17487/RFC2827,		Address Spoofing", BCP 38, RFC 2827, DOI 10.17487/RFC2827,
	May 2000, <https://www.rfc-editor.org/info/bcp38>.		May 2000, <https://www.rfc-editor.org/info/bcp38>.
	[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>.
	skipping to change at page 51, line 47 ¶		skipping to change at page 51, line 36 ¶
	[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC		[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
	2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,		2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
	May 2017, <https://www.rfc-editor.org/info/rfc8174>.		May 2017, <https://www.rfc-editor.org/info/rfc8174>.
	[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6		[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
	(IPv6) Specification", STD 86, RFC 8200,		(IPv6) Specification", STD 86, RFC 8200,
	DOI 10.17487/RFC8200, July 2017,		DOI 10.17487/RFC8200, July 2017,
	<https://www.rfc-editor.org/info/rfc8200>.		<https://www.rfc-editor.org/info/rfc8200>.
	13.2. Informative References		14.2. Informative References
	[DDOS-KREBS]		[DDOS-KREBS]
	Goodin, D., "Record-breaking DDoS reportedly delivered by		Goodin, D., "Record-breaking DDoS reportedly delivered by
	>145k hacked cameras", September 2016,		>145k hacked cameras", September 2016,
	<http://arstechnica.com/security/2016/09/botnet-of-145k-		<http://arstechnica.com/security/2016/09/botnet-of-145k-
	cameras-reportedly-deliver-internets-biggest-ddos-ever/>.		cameras-reportedly-deliver-internets-biggest-ddos-ever/>.
	[I-D.ietf-6lo-ap-nd]		[I-D.ietf-6lo-ap-nd]
	Thubert, P., Sarikaya, B., Sethi, M., and R. Struik,		Thubert, P., Sarikaya, B., Sethi, M., and R. Struik,
	"Address Protected Neighbor Discovery for Low-power and		"Address Protected Neighbor Discovery for Low-power and
	skipping to change at page 52, line 36 ¶		skipping to change at page 52, line 24 ¶
	[I-D.ietf-anima-autonomic-control-plane]		[I-D.ietf-anima-autonomic-control-plane]
	Eckert, T., Behringer, M., and S. Bjarnason, "An Autonomic		Eckert, T., Behringer, M., and S. Bjarnason, "An Autonomic
	Control Plane (ACP)", draft-ietf-anima-autonomic-control-		Control Plane (ACP)", draft-ietf-anima-autonomic-control-
	plane-19 (work in progress), March 2019.		plane-19 (work in progress), March 2019.
	[I-D.ietf-anima-bootstrapping-keyinfra]		[I-D.ietf-anima-bootstrapping-keyinfra]
	Pritikin, M., Richardson, M., Behringer, M., Bjarnason,		Pritikin, M., Richardson, M., Behringer, M., Bjarnason,
	S., and K. Watsen, "Bootstrapping Remote Secure Key		S., and K. Watsen, "Bootstrapping Remote Secure Key
	Infrastructures (BRSKI)", draft-ietf-anima-bootstrapping-		Infrastructures (BRSKI)", draft-ietf-anima-bootstrapping-
	keyinfra-20 (work in progress), May 2019.		keyinfra-22 (work in progress), June 2019.
	[I-D.ietf-intarea-tunnels]		[I-D.ietf-intarea-tunnels]
	Touch, J. and M. Townsley, "IP Tunnels in the Internet		Touch, J. and M. Townsley, "IP Tunnels in the Internet
	Architecture", draft-ietf-intarea-tunnels-09 (work in		Architecture", draft-ietf-intarea-tunnels-09 (work in
	progress), July 2018.		progress), July 2018.
	[I-D.thubert-roll-unaware-leaves]		[I-D.thubert-roll-unaware-leaves]
	Thubert, P., "Routing for RPL Leaves", draft-thubert-roll-		Thubert, P., "Routing for RPL Leaves", draft-thubert-roll-
	unaware-leaves-07 (work in progress), April 2019.		unaware-leaves-07 (work in progress), April 2019.
	skipping to change at page 53, line 19 ¶		skipping to change at page 53, line 5 ¶
	[RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet		[RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet
	Control Message Protocol (ICMPv6) for the Internet		Control Message Protocol (ICMPv6) for the Internet
	Protocol Version 6 (IPv6) Specification", STD 89,		Protocol Version 6 (IPv6) Specification", STD 89,
	RFC 4443, DOI 10.17487/RFC4443, March 2006,		RFC 4443, DOI 10.17487/RFC4443, March 2006,
	<https://www.rfc-editor.org/info/rfc4443>.		<https://www.rfc-editor.org/info/rfc4443>.
	[RFC5406] Bellovin, S., "Guidelines for Specifying the Use of IPsec		[RFC5406] Bellovin, S., "Guidelines for Specifying the Use of IPsec
	Version 2", BCP 146, RFC 5406, DOI 10.17487/RFC5406,		Version 2", BCP 146, RFC 5406, DOI 10.17487/RFC5406,
	February 2009, <https://www.rfc-editor.org/info/rfc5406>.		February 2009, <https://www.rfc-editor.org/info/rfc5406>.
			[RFC6437] Amante, S., Carpenter, B., Jiang, S., and J. Rajahalme,
			"IPv6 Flow Label Specification", RFC 6437,
			DOI 10.17487/RFC6437, November 2011,
			<https://www.rfc-editor.org/info/rfc6437>.
	[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,
	<https://www.rfc-editor.org/info/rfc6775>.		<https://www.rfc-editor.org/info/rfc6775>.
	[RFC6997] Goyal, M., Ed., Baccelli, E., Philipp, M., Brandt, A., and		[RFC6997] Goyal, M., Ed., Baccelli, E., Philipp, M., Brandt, A., and
	J. Martocci, "Reactive Discovery of Point-to-Point Routes		J. Martocci, "Reactive Discovery of Point-to-Point Routes
	in Low-Power and Lossy Networks", RFC 6997,		in Low-Power and Lossy Networks", RFC 6997,
	DOI 10.17487/RFC6997, August 2013,		DOI 10.17487/RFC6997, August 2013,
End of changes. 237 change blocks.
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