draft-ietf-roll-useofrplinfo-31.original		draft-ietf-roll-useofrplinfo-31-MIR.txt
	ROLL Working Group M. Robles		Internet Engineering Task Force (IETF) M. Robles
	Internet-Draft Aalto		Request for Comments: XXXX Aalto/UTN-FRM
	Updates: 6553, 6550, 8138 (if approved) M. Richardson		Updates: 6550, 6553, 8138 M. Richardson
	Intended status: Standards Track SSW		Category: Standards Track SSW
	Expires: January 5, 2020 P. Thubert		ISSN: 2070-1721 P. Thubert
	Cisco		Cisco
	July 4, 2019		August 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-31
	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
	RFC6553 adding a change to the RPL Option Type. Additionally, this		RFC6553 adding a change to the RPL Option Type. Additionally, this
	document updates RFC6550 defining a flag in the DIO Configuration		document updates RFC6550 defining a flag in the DIO Configuration
	Option to indicate about this change and updates RFC8138 as well to		Option to indicate about this change and updates RFC8138 as well to
	consider the new Option Type when the RPL Option is decompressed.		consider the new Option Type when the RPL Option is decompressed.
	Status of This Memo		Status of This Memo
	This Internet-Draft is submitted in full conformance with the		This is an Internet Standards Track document.
	provisions of BCP 78 and BCP 79.
	Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-
	Drafts is at https://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		This document is a product of the Internet Engineering Task Force
	and may be updated, replaced, or obsoleted by other documents at any		(IETF). It represents the consensus of the IETF community. It has
	time. It is inappropriate to use Internet-Drafts as reference		received public review and has been approved for publication by the
	material or to cite them other than as "work in progress."		Internet Engineering Steering Group (IESG). Further information on
			Internet Standards is available in Section 2 of RFC 7841.
	This Internet-Draft will expire on January 5, 2020.		Information about the current status of this document, any errata,
			and how to provide feedback on it may be obtained at
			https://www.rfc-editor.org/info/rfcXXXX.
	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
			RFC XXXX RPL-data-plane August 2019
	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 . . . . . . . . . . . . 4		2. Terminology and Requirements Language . . . . . . . . . . . . 4
	3. RPL Overview . . . . . . . . . . . . . . . . . . . . . . . . 6		3. RPL Overview . . . . . . . . . . . . . . . . . . . . . . . . 6
	4. Updates to RFC6553, RFC6550 and RFC8138 . . . . . . . . . . . 7		4. Updates to RFC6553, RFC6550 and RFC8138 . . . . . . . . . . . 6
	4.1. Updates to RFC6553: Indicating the new RPI value. . . . . 7		4.1. Updates to RFC6553: Indicating the new RPI value. . . . . 6
	4.2. Updates to RFC6550: Indicating the new RPI in the		4.2. Updates to RFC6550: Indicating the new RPI in the
	DODAG Configuration Option Flag. . . . . . . . . . . . . 10		DODAG Configuration Option Flag. . . . . . . . . . . . . 9
	4.3. 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. . . . . . . . . . . . . . . . . . . . 10
	5. Sample/reference topology . . . . . . . . . . . . . . . . . . 12		5. Sample/reference topology . . . . . . . . . . . . . . . . . . 12
	6. Use cases . . . . . . . . . . . . . . . . . . . . . . . . . . 14		6. Use cases . . . . . . . . . . . . . . . . . . . . . . . . . . 14
	7. Storing mode . . . . . . . . . . . . . . . . . . . . . . . . 16		7. Storing mode . . . . . . . . . . . . . . . . . . . . . . . . 16
	7.1. Storing Mode: Interaction between Leaf and Root . . . . . 18		7.1. Storing Mode: Interaction between Leaf and Root . . . . . 18
	7.1.1. SM: Example of Flow from RAL to root . . . . . . . . 18		7.1.1. SM: Example of Flow from RAL to root . . . . . . . . 18
	7.1.2. SM: Example of Flow from root to RAL . . . . . . . . 19		7.1.2. SM: Example of Flow from root to RAL . . . . . . . . 19
	7.1.3. SM: Example of Flow from root to RUL . . . . . . . . 20		7.1.3. SM: Example of Flow from root to RUL . . . . . . . . 20
	7.1.4. SM: Example of Flow from RUL to root . . . . . . . . 20		7.1.4. SM: Example of Flow from RUL to root . . . . . . . . 20
	7.2. SM: Interaction between Leaf and Internet. . . . . . . . 21		7.2. SM: Interaction between Leaf and Internet. . . . . . . . 21
	7.2.1. SM: Example of Flow from RAL to Internet . . . . . . 22		7.2.1. SM: Example of Flow from RAL to Internet . . . . . . 22
	7.2.2. SM: Example of Flow from Internet to RAL . . . . . . 22		7.2.2. SM: Example of Flow from Internet to RAL . . . . . . 22
	7.2.3. SM: Example of Flow from RUL to Internet . . . . . . 23		7.2.3. SM: Example of Flow from RUL to Internet . . . . . . 23
	7.2.4. SM: Example of Flow from Internet to RUL. . . . . . . 24		7.2.4. SM: Example of Flow from Internet to RUL. . . . . . . 24
	7.3. SM: Interaction between Leaf and Leaf . . . . . . . . . . 25		7.3. SM: Interaction between Leaf and Leaf . . . . . . . . . . 25
	7.3.1. SM: Example of Flow from RAL to RAL . . . . . . . . . 25		7.3.1. SM: Example of Flow from RAL to RAL . . . . . . . . . 25
	7.3.2. SM: Example of Flow from RAL to RUL . . . . . . . . . 27		7.3.2. SM: Example of Flow from RAL to RUL . . . . . . . . . 27
	7.3.3. SM: Example of Flow from RUL to RAL . . . . . . . . . 27		7.3.3. SM: Example of Flow from RUL to RAL . . . . . . . . . 27
	7.3.4. SM: Example of Flow from RUL to RUL . . . . . . . . . 29		7.3.4. SM: Example of Flow from RUL to RUL . . . . . . . . . 28
	8. Non Storing mode . . . . . . . . . . . . . . . . . . . . . . 30		8. Non Storing mode . . . . . . . . . . . . . . . . . . . . . . 30
	8.1. Non-Storing Mode: Interaction between Leaf and Root . . . 31		8.1. Non-Storing Mode: Interaction between Leaf and Root . . . 31
	8.1.1. Non-SM: Example of Flow from RAL to root . . . . . . 32		8.1.1. Non-SM: Example of Flow from RAL to root . . . . . . 32
	8.1.2. Non-SM: Example of Flow from root to RAL . . . . . . 32		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		8.1.3. Non-SM: Example of Flow from root to RUL . . . . . . 33
	8.1.4. Non-SM: Example of Flow from RUL to root . . . . . . 34		8.1.4. Non-SM: Example of Flow from RUL to root . . . . . . 34
	8.2. Non-Storing Mode: Interaction between Leaf and Internet . 35		8.2. Non-Storing Mode: Interaction between Leaf and Internet . 35
	8.2.1. Non-SM: Example of Flow from RAL to Internet . . . . 35		8.2.1. Non-SM: Example of Flow from RAL to Internet . . . . 35
	8.2.2. Non-SM: Example of Flow from Internet to RAL . . . . 36		8.2.2. Non-SM: Example of Flow from Internet to RAL . . . . 36
	8.2.3. Non-SM: Example of Flow from RUL to Internet . . . . 37		8.2.3. Non-SM: Example of Flow from RUL to Internet . . . . 37
	8.2.4. Non-SM: Example of Flow from Internet to RUL . . . . 38		8.2.4. Non-SM: Example of Flow from Internet to RUL . . . . 38
			RFC XXXX RPL-data-plane August 2019
	8.3. Non-SM: Interaction between Leafs . . . . . . . . . . . . 39		8.3. Non-SM: Interaction between Leafs . . . . . . . . . . . . 39
	8.3.1. Non-SM: Example of Flow from RAL to RAL . . . . . . . 39		8.3.1. Non-SM: Example of Flow from RAL to RAL . . . . . . . 39
	8.3.2. Non-SM: Example of Flow from RAL to RUL . . . . . . . 41		8.3.2. Non-SM: Example of Flow from RAL to RUL . . . . . . . 41
	8.3.3. Non-SM: Example of Flow from RUL to RAL . . . . . . . 42		8.3.3. Non-SM: Example of Flow from RUL to RAL . . . . . . . 42
	8.3.4. Non-SM: Example of Flow from RUL to RUL . . . . . . . 43		8.3.4. Non-SM: Example of Flow from RUL to RUL . . . . . . . 43
	9. Operational Considerations of supporting		9. Operational Considerations of supporting
	not-RPL-aware-leaves . . . . . . . . . . . . . . . . . . . . 44		RUL-leaves . . . . . . . . . . . . . . . . . . . . . . . . . 44
	10. Operational considerations of introducing 0x23 . . . . . . . 45		10. Operational considerations of introducing 0x23 . . . . . . . 45
	11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 46		11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 46
	12. Security Considerations . . . . . . . . . . . . . . . . . . . 47		12. Security Considerations . . . . . . . . . . . . . . . . . . . 47
	13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 50		13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 50
	14. References . . . . . . . . . . . . . . . . . . . . . . . . . 50		14. References . . . . . . . . . . . . . . . . . . . . . . . . . 50
	14.1. Normative References . . . . . . . . . . . . . . . . . . 50		14.1. Normative References . . . . . . . . . . . . . . . . . . 50
	14.2. Informative References . . . . . . . . . . . . . . . . . 51		14.2. Informative References . . . . . . . . . . . . . . . . . 52
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 54		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 54
	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
	skipping to change at page 4, line 12 ¶		skipping to change at page 4, line 5 ¶
	The ROLL WG analysized how [RFC2460] rules apply to storing and non-		The ROLL WG analysized how [RFC2460] rules apply to storing and non-
	storing use of RPL. The result was 24 data plane use cases. They		storing use of RPL. The result was 24 data plane use cases. They
	are exhaustively outlined here in order to be completely unambiguous.		are exhaustively outlined here in order to be completely unambiguous.
	During the processing of this document, new rules were published as		During the processing of this document, new rules were published as
	[RFC8200], and this document was updated to reflect the normative		[RFC8200], and this document was updated to reflect the normative
	changes in that document.		changes in that document.
	This document updates RFC6553, changing the RPI option value to make		This document updates RFC6553, changing the RPI option value to make
	RFC8200 routers ignore this option by default.		RFC8200 routers ignore this option by default.
			RFC XXXX RPL-data-plane August 2019
	A Routing Header Dispatch for 6LoWPAN (6LoRH)([RFC8138]) defines a		A Routing Header Dispatch for 6LoWPAN (6LoRH)([RFC8138]) defines a
	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 [IP-TUNNELS] that
	[I-D.ietf-intarea-tunnels] that explains the relationship of IP		explains the relationship of IP tunnels to existing protocol layers
	tunnels to existing protocol layers and the challenges in supporting		and the challenges in supporting IP tunneling.
	IP tunneling.
	Non-constrained uses of RPL are not in scope of this document, and		Non-constrained uses of RPL are not in scope of this document, and
	applicability statements for those uses may provide different advice,		applicability statements for those uses may provide different advice,
	E.g. [I-D.ietf-anima-autonomic-control-plane].		E.g. [AUTONOMIC-CONTROL].
	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 provides a RPL Overview. Section 4
	RFC6550 and RFC 8138. Section 4 provides the reference topology used		describes the updates to RFC6553, RFC6550 and RFC 8138. Section 5
	for the uses cases. Section 5 describes the uses cases included.		provides the reference topology used for the uses cases. Section 6
	Section 6 describes the storing mode cases and section 7 the non-		describes the uses cases included. Section 7 describes the storing
	storing mode cases. Section 8 describes the operational		mode cases and section 8 the non-storing mode cases. Section 9
	considerations of supporting not-RPL-aware-leaves. Section 9 depicts		describes the operational considerations of supporting RPL-unaware-
	operational considerations for the proposed change on RPL Option		leaves. Section 10 depicts operational considerations for the
	type, section 10 the IANA considerations and then section 11		proposed change on RPL Option type, section 11 the IANA
	describes the security aspects.		considerations and then section 12 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: LLN, RPL,		Terminology defined in [RFC7102] applies to this document: LLN, RPL,
	RPL Domain and ROLL.		RPL Domain and ROLL.
	RPL-aware-node: A device which implements RPL. Please note that the		RPL-aware-node: A device which implements RPL. Please note that the
	device can be found inside the LLN or outside LLN.		device can be found inside the LLN or outside LLN.
	RPL-Aware-Leaf(RAL): A RPL-aware-node which is a leaf of a		RPL-Aware-Leaf(RAL): A RPL-aware-node which is a leaf of a
	(Destination Oriented Directed Acyclic Graph) DODAG.		(Destination Oriented Directed Acyclic Graph) DODAG.
			RFC XXXX RPL-data-plane August 2019
	RPL-unaware-node: A device which does not implement RPL, thus the		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.		inside the LLN.
	RPL-Unaware-Leaf(RUL): A RPL-unaware-node which is a leaf of a		RPL-Unaware-Leaf(RUL): A RPL-unaware-node which is a leaf of a
	(Destination Oriented Directed Acyclic Graph) DODAG.		(Destination Oriented Directed Acyclic Graph) DODAG.
	6LoWPAN Node (6LN): [RFC6775] defines it as: "A 6LoWPAN node is any		6LoWPAN Node (6LN): [RFC6775] defines it as: "A 6LoWPAN node is any
	host or router participating in a LoWPAN. This term is used when		host or router participating in a LoWPAN. This term is used when
	referring to situations in which either a host or router can play the		referring to situations in which either a host or router can play the
	skipping to change at page 5, line 51 ¶		skipping to change at page 5, line 44 ¶
	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).		(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-		Non-Storing Mode (Non-SM): RPL mode of operation in which the RPL-
	aware-nodes send information to the root about its parents. Thus,		aware-nodes send information to the root about its parents. Thus,
	the root know the topology, then the intermediate 6LRs do not		the root know the topology, then the intermediate 6LRs do not
	maintain routing state so that source routing is needed.		maintain routing state so that source routing is needed.
	Storing Mode (SM): RPL mode of operation in which RPL-aware-nodes		Storing Mode (SM): RPL mode of operation in which RPL-aware-nodes
	(6LRs) maintain routing state (of the children) so that source		(6LRs) maintain routing state (of the children) so that source
	routing is not needed.		routing is not needed.
	Due to lack of space in some figures (tables) we refers IPv6-in-IPv6		Note: Due to lack of space in some figures (tables) we refer to IPv6-
	as IP6-IP6.		in-IPv6 as IP6-IP6.
			RFC XXXX RPL-data-plane August 2019
	3. RPL Overview		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.
	+--------------+		+--------------+
	skipping to change at page 7, line 10 ¶		skipping to change at page 6, line 49 ¶
	routed. A RPL Instance is either fully storing or fully non-storing,		routed. A RPL Instance is either fully storing or fully non-storing,
	i.e. a RPL Instance with a combination of storing and non-storing		i.e. a RPL Instance with a combination of storing and non-storing
	nodes is not supported with the current specifications at the time of		nodes is not supported with the current specifications at the time of
	writing this document.		writing this document.
	4. Updates to RFC6553, RFC6550 and RFC8138		4. Updates to RFC6553, RFC6550 and RFC8138
	4.1. 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 RPL-unaware node through Internet
	Internet (see Section 7.2.1), without requiring IPv6-in-IPv6		(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
			RFC XXXX RPL-data-plane August 2019
	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.
	+-------+-------------------+----------------+-----------+		+-------+-------------------+----------------+-----------+
	| Hex | Binary Value | Description | Reference |		| Hex | Binary Value | Description | Reference |
	+ Value +-------------------+ + +		+ Value +-------------------+ + +
	| | act | chg | rest | | |		| | act | chg | rest | | |
	+-------+-----+-----+-------+----------------+-----------+		+-------+-----+-----+-------+----------------+-----------+
	skipping to change at page 8, line 17 ¶		skipping to change at page 8, line 4 ¶
	modifies this behavior in order to reduce the dependency on IPv6-in-		modifies this behavior in order to reduce the dependency on IPv6-in-
	IPv6 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".		do so".
	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,
			RFC XXXX RPL-data-plane August 2019
	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
	same, irrespective of the configuration.		same, irrespective of the configuration.
	Thus, this document updates the Option Type field to (Figure 3): the		Thus, this document updates the Option Type field to (Figure 3): the
	two high order bits MUST be set to '00' and the third bit is equal to		two high order bits MUST be set to '00' and the third bit is equal to
	skipping to change at page 9, line 25 ¶		skipping to change at page 9, line 4 ¶
	Without the signaling described below, this change would otherwise		Without the signaling described below, this change would otherwise
	create a lack of interoperation (flag day) for existing networks		create a lack of interoperation (flag day) for existing networks
	which are currently using 0x63 as the RPI value. A move to 0x23 will		which are currently using 0x63 as the RPI value. A move to 0x23 will
	not be understood by those networks. It is suggested that RPL		not be understood by those networks. It is suggested that RPL
	implementations accept both 0x63 and 0x23 when processing the header.		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] - Section 4.2). It allows to the network to be		changed by [RFC8200] - Section 4.2). It allows to the network to be
			RFC XXXX RPL-data-plane August 2019
	incrementally upgraded, and for the DODAG root to know which parts of		incrementally upgraded, and for the DODAG root to know which parts of
	the network 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
	skipping to change at page 10, line 24 ¶		skipping to change at page 10, line 4 ¶
	4.2. 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
			RFC XXXX RPL-data-plane August 2019
	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
	RPI.		RPI.
	This is done via a DODAG Configuration Option flag which will		This is done via a DODAG Configuration Option flag which will
	propagate through the network. If the flag is received with a value		propagate through the network. If the flag is received with a value
	zero (which is the default), then new nodes will remain in RFC6553		zero (which is the default), then new nodes will remain in RFC6553
	Compatible Mode; originating traffic with the old-RPI (0x63) value.		Compatible Mode; originating traffic with the old-RPI (0x63) value.
	As stated in [RFC6550] the DODAG Configuration option is present in		As stated in [RFC6550] the DODAG Configuration option is present in
	skipping to change at page 11, line 26 ¶		skipping to change at page 11, line 5 ¶
	node would be set with the flag unset until a DIO message is received		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		with the flag set indicating the new RPI value. The node sets to
	0x23 if the node supports this feature.		0x23 if the node supports this feature.
	4.3. 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).
			RFC XXXX RPL-data-plane August 2019
	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 4.2. 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.
	skipping to change at page 12, line 5 ¶		skipping to change at page 11, line 32 ¶
	In Storing Mode, for the examples of Flow from RAL to RUL and RUL to		In Storing Mode, for the examples of Flow from RAL to RUL and RUL to
	RUL comprise an IPv6-in-IPv6 and RPI compression headers. The use of		RUL comprise an IPv6-in-IPv6 and RPI compression headers. The use of
	the IPv6-in-IPv6 header is MANDATORY in this case, and it SHOULD be		the IPv6-in-IPv6 header is MANDATORY in this case, and it SHOULD be
	compressed with [RFC8138] section 7. Figure 5 illustrates the case		compressed with [RFC8138] section 7. Figure 5 illustrates the case
	in Storing mode where the packet is received from the Internet, then		in Storing mode where the packet is received from the Internet, then
	the root encapsulates the packet to insert the RPI. In that example,		the root encapsulates the packet to insert the RPI. In that example,
	the leaf is not known to support RFC 8138, and the packet is		the leaf is not known to support RFC 8138, and the packet is
	encapsulated to the 6LR that is the parent and last hop to the final		encapsulated to the 6LR that is the parent and last hop to the final
	destination.		destination.
	+-+ ... -+-+ ... +-+- ... -+-+- .... +-+-+-+ ... +-+-+ ... -+ ... +-...		+-+ ... -+-+ ... +-+- ... -+-+- +-+-+-+ ... +-+-+ ... -+++ ... +-...
	|11110001|SRH-6LoRH| RPI- |IPv6-in-IPv6| NH=1 |11110CPP| UDP | UDP		|11110001|SRH-6LoRH| RPI- |IP-in-IP| NH=1 |11110CPP| UDP | UDP
	|Page 1 |Type1 S=0| 6LoRH | 6LoRH |LOWPAN_IPHC| UDP | hdr |Payld		|Page 1 |Type1 S=0| 6LoRH |6LoRH |LOWPAN_IPHC| UDP | hdr |Payld
	+-+ ... -+-+ ... +-+- ... -+-+-- ...+-+-+-+-+ ... +-+-+ ... -+ ... +-...		+-+ ... -+-+ ... +-+- ... -+-+-.+-+-+-+-+ ... +-+-+ ... -+ ... +-...
	<-4bytes-> <- RFC 6282 ->		<-4bytes-> <- RFC 6282 ->
	No RPL artifact		No RPL artifact
	Figure 5: RPI Inserted by the Root in Storing Mode		Figure 5: RPI Inserted by the Root in Storing Mode
	In Figure 5, the source of the IPv6-in-IPv6 encapsulation is the		In Figure 5, the source of the IPv6-in-IPv6 encapsulation is the
	Root, so it is elided in the IPv6-in-IPv6 6LoRH. The destination is		Root, so it is elided in the IP-in-IP 6LoRH. The destination is the
	the parent 6LR of the destination of the inner packet so it cannot be		parent 6LR of the destination of the inner packet so it cannot be
	elided. It is placed as the single entry in an SRH-6LoRH as the		elided. It is placed as the single entry in an SRH-6LoRH as the
	first 6LoRH. There is a single entry so the SRH-6LoRH Size is 0. In		first 6LoRH. There is a single entry so the SRH-6LoRH Size is 0. In
	that example, the type is 1 so the 6LR address is compressed to 2		that example, the type is 1 so the 6LR address is compressed to 2
	bytes. It results that the total length of the SRH-6LoRH is 4 bytes.		bytes. It results that the total length of the SRH-6LoRH is 4 bytes.
	Follows the RPI-6LoRH and then the IPv6-in-IPv6 6LoRH. When the		Follows the RPI-6LoRH and then the IP-in-IP 6LoRH. When the IP-in-IP
	IPv6-in-IPv6 6LoRH is removed, all the router headers that precede it		6LoRH is removed, all the router headers that precede it are also
	are also removed. The Paging Dispatch [RFC8025] may also be removed		removed. The Paging Dispatch [RFC8025] may also be removed if there
	if there was no previous Page change to a Page other than 0 or 1,		was no previous Page change to a Page other than 0 or 1, since the
	since the LOWPAN_IPHC is encoded in the same fashion in the default
	Page 0 and in Page 1. The resulting packet to the destination is the		RFC XXXX RPL-data-plane August 2019
	inner packet compressed with [RFC6282].
			LOWPAN_IPHC is encoded in the same fashion in the default Page 0 and
			in Page 1. The resulting packet to the destination is the inner
			packet compressed with [RFC6282].
	5. Sample/reference topology		5. Sample/reference topology
	A RPL network in general is composed of a 6LBR, Backbone Router		A RPL network in general is composed of a 6LBR, Backbone Router
	(6BBR), 6LR and 6LN as leaf logically organized in a DODAG structure.		(6BBR), 6LR and 6LN 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 and is the root of the DODAG, thus
	the figure.		the 6BBR is not present in the figure.
	The 6LN leaves (RAL) 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 RUL (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.
			RFC XXXX RPL-data-plane August 2019
	+------------+		+------------+
	| INTERNET ----------+		| INTERNET ----------+
	| | |		| | |
	+------------+ |		+------------+ |
	|		|
	|		|
	|		|
	A |		A |
	+-------+		+-------+
	|6LBR |		|6LBR |
	skipping to change at page 14, line 5 ¶		skipping to change at page 14, line 5 ¶
	| | | | |		| | | | |
	| | | I | J |		| | | I | J |
	F | | G | H | |		F | | G | H | |
	+-----+-+ +-|-----+ +---|--+ +---|---+ +---|---+		+-----+-+ +-|-----+ +---|--+ +---|---+ +---|---+
	| RAL | | RUL | | RAL | | RAL | | RUL |		| 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.
			RFC XXXX RPL-data-plane August 2019
	6. 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 use cases describe the communication in the following cases: -		The use cases describe the communication in the following cases: -
	skipping to change at page 14, line 44 ¶		skipping to change at page 14, line 46 ¶
	RAL to Internet		RAL to Internet
	Internet to RAL		Internet to RAL
	RUL to Internet		RUL to Internet
	Internet to RUL		Internet to RUL
	Interaction between Leafs:		Interaction between Leafs:
	RAL to RAL (storing and non-storing)		RAL to RAL
	RAL to RUL (non-storing)		RAL to RUL
	RUL to RAL (storing and non-storing)		RUL to RAL
	RUL to RUL (non-storing)		RUL to RUL
			RFC XXXX RPL-data-plane August 2019
	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].		outlined in [RFC8200].
	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
	skipping to change at page 15, line 44 ¶		skipping to change at page 15, line 46 ¶
	applied across these headers, but it can not secure the values which		applied across these headers, but it can not secure the values which
	mutate.		mutate.
	RPI MUST be present in every single RPL data packet.		RPI MUST be present in every single RPL data packet.
	Prior to [RFC8138], there was significant interest in removing the		Prior to [RFC8138], there was significant interest in removing the
	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 [AUTONOMIC-CONTROL].
	[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.
	The uses cases are delineated based on the following requirements:		The uses cases are delineated based on the following requirements:
	The RPI option has to be in every packet that traverses the LLN.		The RPI option has to be in every packet that traverses the LLN.
	- Because of (1), packets from the Internet have to be		RFC XXXX RPL-data-plane August 2019
	encapsulated.
			- Because of the previous requirement, packets from the Internet
			have to be encapsulated.
	- A Header cannot be inserted or removed on the fly inside an IPv6		- A Header cannot be inserted or removed on the fly inside an IPv6
	packet that is being routed.		packet that is being routed.
	- Extension headers may not be added or removed except by the		- Extension headers may not be added or removed except by the
	sender or the receiver.		sender or the receiver.
	- RPI and RH3 headers may be modified by routers on the path of		- RPI and RH3 headers may be modified by routers on the path of
	the packet without the need to add and remove an encapsulating		the packet without the need to add and remove an encapsulating
	header.		header.
	skipping to change at page 16, line 30 ¶		skipping to change at page 16, line 32 ¶
	addressed to the intermediate router.		addressed to the intermediate router.
	- Non-storing mode requires downstream encapsulation by root for		- Non-storing mode requires downstream encapsulation by root for
	RH3.		RH3.
	The uses cases are delineated based on the following assumptions:		The uses cases are delineated based on the following assumptions:
	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).
	- Each IPv6 node (including Internet routers) obeys [RFC8200]		- Each IPv6 node (including Internet routers) obeys [RFC8200] RFC
	8200, so that 0x23 RPI can be safely inserted.		8200, so that 0x23 RPI can be safely inserted.
	- All 6LRs obey [RFC8200].		- All 6LRs obey RFC 8200 [RFC8200].
	- The RPI is ignored at the IPv6 dst node (RPL-unaware-leaf).		- The RPI is ignored at the IPv6 dst node (RUL).
	- 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.
	- Non-constrained uses of RPL are not in scope of this document.		- Non-constrained uses of RPL are not in scope of this document.
	- Compression is based on [RFC8138].		- Compression is based on [RFC8138].
	- The flow label [RFC6437] is not needed in RPL.		- The flow label [RFC6437] is not needed in RPL.
	7. Storing mode		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.
			RFC XXXX RPL-data-plane August 2019
	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
	RAL 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"). In the hop-by-hop basis,		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 destination address for the next hop is the link-layer address of
	the next hop.		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".
	skipping to change at page 18, line 5 ¶		skipping to change at page 18, line 5 ¶
	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 are the intermediate routers 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).
			RFC XXXX RPL-data-plane August 2019
	+---------------------+--------------+------------+------------------+		+---------------------+--------------+------------+------------------+
	| Interaction between | Use Case |IPv6-in-IPv6| IPv6-in-IPv6 dst |		| Interaction between | Use Case |IPv6-in-IPv6| IPv6-in-IPv6 dst |
	+---------------------+--------------+------------+------------------+		+---------------------+--------------+------------+------------------+
	| | RAL to root | No | No |		| | RAL to root | No | No |
	+ +--------------+------------+------------------+		+ +--------------+------------+------------------+
	| Leaf - Root | root to RAL | No | No |		| Leaf - Root | root to RAL | No | No |
	+ +--------------+------------+------------------+		+ +--------------+------------+------------------+
	| | root to RUL | No | No |		| | root to RUL | No | No |
	+ +--------------+------------+------------------+		+ +--------------+------------+------------------+
	| | RUL to root | must | root |		| | RUL to root | must | hop or root |
	+---------------------+--------------+------------+------------------+		+---------------------+--------------+------------+------------------+
	| | RAL to Int | No | No |		| | RAL to Int | No | No |
	+ +--------------+------------+------------------+		+ +--------------+------------+------------------+
	| Leaf - Internet | Int to RAL | must | RAL (tgt) |		| Leaf - Internet | Int to RAL | must | RAL (tgt) |
	+ +--------------+------------+------------------+		+ +--------------+------------+------------------+
	| | RUL to Int | must | root |		| | RUL to Int | must | hop or root |
	+ +--------------+------------+------------------+		+ +--------------+------------+------------------+
	| | Int to RUL | must | hop |		| | Int to RUL | must | hop |
	+---------------------+--------------+------------+------------------+		+---------------------+--------------+------------+------------------+
	| | RAL to RAL | No | No |		| | RAL to RAL | No | No |
	+ +--------------+------------+------------------+		+ +--------------+------------+------------------+
	| | RAL to RUL | No | No |		| | RAL to RUL | No | No |
	+ Leaf - Leaf +--------------+------------+------------------+		+ Leaf - Leaf +--------------+------------+------------------+
	| | RUL to RAL | must | RAL (tgt) |		| | RUL to RAL | must | RAL (tgt) |
	+ +--------------+------------+------------------+		+ +--------------+------------+------------------+
	| | RUL to RUL | must | hop |		| | RUL to RUL | must | hop |
	skipping to change at page 19, line 5 ¶		skipping to change at page 19, line 5 ¶
	RUL to root		RUL to root
	root to RUL		root to RUL
	7.1.1. SM: Example of Flow from RAL 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.
			RFC XXXX RPL-data-plane August 2019
	In this case the flow comprises:		In this case the flow comprises:
	RAL (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)
	The 6LN (Node F) inserts the RPI header, and sends the packet to 6LR		The RAL (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 D) 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 RAL 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 RAL can know the
	address of the 6LBR because it knows the address of the root via the		address of the 6LBR because it knows the address of the root via the
	DODAGID in the DIO messages.		DODAGID in the DIO messages.
	The Table 1 summarizes what headers are needed for this use case.		The Table 1 summarizes what headers are needed for this use case.
	+-------------------+---------+-------+----------+		+-------------------+---------+-------+----------+
	| Header | 6LN src | 6LR_i | 6LBR dst |		| Header | RAL 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: SM: Summary of the use of headers from RAL to root		Table 1: SM: Summary of the use of headers from RAL to root
	skipping to change at page 19, line 51 ¶		skipping to change at page 19, line 53 ¶
	In this case the flow comprises:		In this case the flow comprises:
	root (6LBR) --> 6LR_i --> RAL (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 RAL and the RPI removed.
			RFC XXXX RPL-data-plane August 2019
	No IPv6-in-IPv6 header is required.		No IPv6-in-IPv6 header is required.
	The Table 2 summarizes what headers are needed for this use case.		The Table 2 summarizes what headers are needed for this use case.
	+-------------------+------+-------+------+		+-------------------+----------+-------+---------+
	| Header | 6LBR | 6LR_i | 6LN |		| Header | 6LBR src | 6LR_i | RAL 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 2: SM: Summary of the use of headers from root to RAL		Table 2: SM: Summary of the use of headers from root to RAL
	7.1.3. SM: Example of Flow from root to RUL		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 --> RUL (IPv6)		root (6LBR) --> 6LR_i --> RUL (IPv6 dst node)
	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 RUL, this situation is
	situation is identical to the previous scenario.		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 | RUL (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: SM: Summary of the use of headers from root to RUL		Table 3: SM: Summary of the use of headers from root to RUL
	7.1.4. SM: Example of Flow from RUL 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:
	RUL (IPv6) --> 6LR_1 --> 6LR_i --> root (6LBR)		RUL (IPv6 src node) --> 6LR_1 --> 6LR_i --> root (6LBR)
			RFC XXXX RPL-data-plane August 2019
	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. [1] refers the case where the IPv6-in-IPv6 header		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		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).		IPv6-in-IPv6 header is addressed to the root (Node A).
	+-----------+------+--------------+-----------------+------------------+		+-----------+------+--------------+-----------------+------------------+
	| Header | IPv6 | 6LR_1 | 6LR_i | 6LBR dst |		| Header | RUL | 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] |IP6-IP6(RPI)[1][2]|
	| headers | | | | |		| headers | | | | |
	+-----------+------+--------------+-----------------+------------------+		+-----------+------+--------------+-----------------+------------------+
	| Re-added | -- | -- | IP6-IP6(RPI)[1] | -- |		| Re-added | -- | -- | -- | -- |
	| headers | | | | |		| headers | | | | |
	+-----------+------+--------------+-----------------+------------------+		+-----------+------+--------------+-----------------+------------------+
	| Modified | -- | -- | IP6-IP6(RPI)[2] | -- |		| Modified | -- | -- | IP6-IP6(RPI)[2] | -- |
	| headers | | | | |		| headers | | | | |
	+-----------+------+--------------+-----------------+------------------+		+-----------+------+--------------+-----------------+------------------+
	| Untouched | -- | -- | -- | -- |		| Untouched | -- | -- | -- | -- |
	| headers | | | | |		| headers | | | | |
	+-----------+------+--------------+-----------------+------------------+		+-----------+------+--------------+-----------------+------------------+
	Figure 8: SM: Summary of the use of headers from RUL to root.		Figure 8: SM: Summary of the use of headers from RUL to root.
	skipping to change at page 22, line 4 ¶		skipping to change at page 22, line 4 ¶
	7.2. SM: 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,
	RAL to Internet		RAL to Internet
	Internet to RAL		Internet to RAL
	RUL to Internet		RUL to Internet
			RFC XXXX RPL-data-plane August 2019
	Internet to RUL		Internet to RUL
	7.2.1. SM: Example of Flow from RAL 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:
	RAL (6LN) --> 6LR_i --> root (6LBR) --> Internet		RAL (6LN) --> 6LR_i --> root (6LBR) --> Internet
	skipping to change at page 22, line 26 ¶		skipping to change at page 22, line 29 ¶
	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-aware-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 | RAL 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: SM: Summary of the use of headers from RAL to Internet		Table 4: SM: Summary of the use of headers from RAL to Internet
	skipping to change at page 22, line 48 ¶		skipping to change at page 22, line 51 ¶
	In this case the flow comprises:		In this case the flow comprises:
	Internet --> root (6LBR) --> 6LR_i --> RAL (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 RAL) 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 the RAL the RPI header is
	and the packet processed.		removed and the packet processed.
			RFC XXXX RPL-data-plane August 2019
	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.		for this use case.
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	| Header | Internet | 6LBR | 6LR_i | 6LN dst |		| Header | Internet | 6LBR | 6LR_i | RAL dst |
	| | src | | | |		| | src | | | |
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	| Inserted | -- | IP6-IP6(RPI) | -- | -- |		| Inserted | -- | IP6-IP6(RPI) | -- | -- |
	| headers | | | | |		| headers | | | | |
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	| Removed | -- | -- | -- | IP6-IP6(RPI) |		| Removed | -- | -- | -- | IP6-IP6(RPI) |
	| headers | | | | |		| headers | | | | |
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	| Re-added | -- | -- | -- | -- |		| Re-added | -- | -- | -- | -- |
	| headers | | | | |		| headers | | | | |
	skipping to change at page 23, line 34 ¶		skipping to change at page 23, line 36 ¶
	| Untouched | -- | -- | -- | -- |		| Untouched | -- | -- | -- | -- |
	| headers | | | | |		| headers | | | | |
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	Figure 9: SM: Summary of the use of headers from Internet to RAL.		Figure 9: SM: Summary of the use of headers from Internet to RAL.
	7.2.3. SM: Example of Flow from RUL 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:
	RUL (IPv6) --> 6LR_1 --> 6LR_i -->root (6LBR) --> Internet		RUL (IPv6 src node) --> 6LR_1 --> 6LR_i -->root (6LBR) --> 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, for details check [RFC6437].		sending to the Internet, for details check [RFC6437].
			RFC XXXX RPL-data-plane August 2019
	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.		for this use case. In the table, [1] shows the case when packet is
			addressed to the root. [2] shows the case when the packet is
			addressed hop-by-hop.
	+---------+-------+------------+--------------+-------------+--------+		+---------+-------+------------+--------------+-------------+--------+
	| 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 | | | | |
			| | (RUL) | | | | |
	+---------+-------+------------+--------------+-------------+--------+		+---------+-------+------------+--------------+-------------+--------+
	| 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)| -- |
	| headers | | | [2] | [1][2] | |		| headers | | | [2] | [1][2] | |
	+---------+-------+------------+--------------+-------------+--------+		+---------+-------+------------+--------------+-------------+--------+
	| Re-added| -- | -- | -- | -- | -- |		| Re-added| -- | -- | -- | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	+---------+-------+------------+--------------+-------------+--------+		+---------+-------+------------+--------------+-------------+--------+
	| Modified| -- | -- | IP6-IP6(RPI) | -- | -- |		| Modified| -- | -- | IP6-IP6(RPI) | -- | -- |
	| headers | | | [1] | | |		| headers | | | [1] | | |
	+---------+-------+------------+--------------+-------------+--------+		+---------+-------+------------+--------------+-------------+--------+
	|Untouched| -- | -- | -- | -- | -- |		|Untouched| -- | -- | -- | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	+---------+-------+------------+--------------+-------------+--------+		+---------+-------+------------+--------------+-------------+--------+
	Figure 10: SM: Summary of the use of headers from RUL to Internet.		Figure 10: SM: Summary of the use of headers from RUL to Internet.
	[1] Case when packet is addressed to the root. [2] Case when the
	packet is addressed hop-by-hop.
	7.2.4. SM: Example of Flow from Internet to RUL.		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 --> RUL (IPv6)		Internet --> root (6LBR) --> 6LR_i --> RUL (IPv6 dst node)
	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. Further details about
	this are mentioned in [I-D.thubert-roll-unaware-leaves], which		this are mentioned in [RPL-LEAVES], which specifies RPL routing for a
	specifies RPL routing for a 6LN acting as a plain host and not aware		6LN acting as a plain host and not being aware of RPL.
	of RPL.
			RFC XXXX RPL-data-plane August 2019
	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 [RFC8138][RFC6437].		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.		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) | IP6-IP6(RPI) | -- |
	| headers | | | | |		| headers | | | | |
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	| Removed | -- | -- | | IP6-IP6(RPI)|		| Removed | -- | -- | IP6-IP6(RPI) | IP6-IP6(RPI)|
	| headers | | | | RPI Ignored |		| headers | | | | RPI Ignored |
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	| Re-added | -- | -- | -- | -- |		| Re-added | -- | -- | -- | -- |
	| headers | | | | |		| headers | | | | |
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	| Modified | -- | -- | IP6-IP6(RPI) | -- |		| Modified | -- | -- | -- | -- |
	| headers | | | | |		| headers | | | | |
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	| Untouched | -- | -- | -- | -- |		| Untouched | -- | -- | -- | -- |
	| headers | | | | |		| headers | | | | |
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	Figure 11: SM: Summary of the use of headers from Internet to RUL.		Figure 11: SM: Summary of the use of headers from Internet to RUL.
	7.3. SM: Interaction between Leaf and Leaf		7.3. SM: Interaction between Leaf and Leaf
	skipping to change at page 26, line 5 ¶		skipping to change at page 26, line 5 ¶
	RUL to RUL		RUL to RUL
	7.3.1. SM: Example of Flow from RAL to RAL		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].
			RFC XXXX RPL-data-plane August 2019
	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		RAL src (6LN) --> 6LR_ia --> common parent (6LR_x) --> 6LR_id --> RAL
			dst (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) are the intermediate routers from source to the		6LR_ia (Node D) are the intermediate routers from source to the
	common parent (6LR_x) (Node B) In this case, 1 <= ia <= n, n is the		common parent (6LR_x) (Node B). In this case, 1 <= ia <= n, n is the
	number of routers (6LR) that the packet goes through from 6LN (Node		number of routers (6LR) that the packet goes through from RAL (Node
	F) to the common parent (6LR_x).		F) to the common parent 6LR_x (Node B).
	6LR_id (Node E) are the intermediate routers 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 RAL (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 RAL (Node H).
	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 decreasing to increasing 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.
	+---------------+--------+--------+---------------+--------+--------+		+---------------+--------+--------+---------------+--------+--------+
	| Header | 6LN | 6LR_ia | 6LR_x (common | 6LR_id | 6LN |		| Header | RAL | 6LR_ia | 6LR_x (common | 6LR_id | RAL |
	| | src | | parent) | | dst |		| | src | | parent) | | dst |
	+---------------+--------+--------+---------------+--------+--------+		+---------------+--------+--------+---------------+--------+--------+
	| Inserted | RPI | -- | -- | -- | -- |		| Inserted | RPI | -- | -- | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	| 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: SM: Summary of the use of headers for RAL to RAL		Table 5: SM: Summary of the use of headers for RAL to RAL
			RFC XXXX RPL-data-plane August 2019
	7.3.2. SM: Example of Flow from RAL to RUL		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		RAL src (6LN) --> 6LR_ia --> common parent (6LR_x) --> 6LR_id --> RUL
	6LN (IPv6)		(IPv6 dst node)
	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 are the intermediate routers from source (6LN) to the common		6LR_ia are the intermediate routers from source (RAL) to the common
	parent (6LR_x) In this case, 1 <= ia <= n, n is the number of routers		parent (6LR_x) In this case, 1 <= ia <= n, n is the number of routers
	(6LR) that the packet goes through from 6LN to the common parent		(6LR) that the packet goes through from RAL to the common parent
	(6LR_x).		(6LR_x).
	6LR_id (Node E) are the intermediate routers 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 RUL (Node G). In this case, 1 <= id
	In this case, 1 <= id <= m, m is the number of routers (6LR) that the		<= m, m is the number of routers (6LR) that the packet goes through
	packet goes through from the common parent (6LR_x) to destination		from the common parent (6LR_x) to destination RUL.
	6LN.
	This situation is identical to the previous situation Section 7.3.1		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 | RAL | 6LR_ia | 6LR_x(common | 6LR_id | RUL dst |
	| | src | | parent) | | node |		| | src | | parent) | | |
	+-----------+------+--------+---------------+--------+--------------+		+-----------+------+--------+---------------+--------+--------------+
	| 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: SM: Summary of the use of headers for RAL to RUL		Table 6: SM: Summary of the use of headers for RAL to RUL
	7.3.3. SM: Example of Flow from RUL to RAL		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) -->		RUL (IPv6 src node) --> 6LR_ia --> common parent (6LR_x) --> 6LR_id
	6LR_id --> 6LN		--> RAL dst (6LN)
			RFC XXXX RPL-data-plane August 2019
	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) are the intermediate routers from source (not-RPL-		6LR_ia (Node E) are the intermediate routers from source (RUL) (Node
	aware 6LN (IPv6)) (Node G) to the common parent (6LR_x) (Node B). In		G) to the common parent (6LR_x) (Node B). In this case, 1 <= ia <=
	this case, 1 <= ia <= n, n is the number of routers (6LR) that the		n, n is the number of routers (6LR) that the packet goes through from
	packet ges through from source to the common parent.		source to the common parent.
	6LR_id (Node D) are the intermediate routers 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 RAL (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 the destination RAL.
	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 RUL (Node G)
	(Node G) and inserts and the RPI header encapsulated in IPv6-in-IPv6		and inserts the RPI header encapsulated in a IPv6-in-IPv6 header.
	header. The IPv6-in-IPv6 header is addressed to the destination 6LN		The IPv6-in-IPv6 header is addressed to the destination RAL (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.		for this use case.
	+---------+-----+------------+-------------+-------------+------------+		+---------+-----+------------+-------------+-------------+------------+
	| Header |IPv6 | 6LR_ia | Common | 6LR_id | 6LN |		| Header |RUL | 6LR_ia | Common | 6LR_id | RAL |
	| |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)|
	| headers | | | | | |		| headers | | | | | |
	+---------+-----+------------+-------------+-------------+------------+		+---------+-----+------------+-------------+-------------+------------+
	| Re-added| -- | -- | -- | -- | -- |		| Re-added| -- | -- | -- | -- | -- |
	skipping to change at page 29, line 9 ¶		skipping to change at page 29, line 5 ¶
	|Untouched| -- | -- | -- | -- | -- |		|Untouched| -- | -- | -- | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	+---------+-----+------------+-------------+-------------+------------+		+---------+-----+------------+-------------+-------------+------------+
	Figure 12: SM: Summary of the use of headers from RUL to RAL.		Figure 12: SM: Summary of the use of headers from RUL to RAL.
	7.3.4. SM: Example of Flow from RUL to RUL		7.3.4. SM: Example of Flow from RUL to RUL
	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		RFC XXXX RPL-data-plane August 2019
	--> not-RPL-aware 6LN (IPv6 dst)
			RUL (IPv6 src node)--> 6LR_1--> 6LR_ia --> 6LBR --> 6LR_id --> RUL
			(IPv6 dst node)
	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 RUL source (Node G) to the root (6LBR) (Node A). In
	(Node A). In this case, "1 < ia <= n", n is the number of routers		this case, "1 < ia <= n", n is the number of routers (6LR) that the
	(6LR) that the packet goes through from IPv6 src to the root.		packet goes through from the RUL to the root.
	6LR_id (Node C) are the intermediate routers from the root (Node A)		6LR_id (Node C) are the intermediate routers from the root (Node A)
	to the destination Node J. In this case, 1 <= id <= m, m is the		to the destination RUL dst node (Node J). In this case, 1 <= id <=
	number of routers (6LR) that the packet goes through from the root to		m, m is the number of routers (6LR) that the packet goes through from
	destination (IPv6 dst).		the root to destination RUL.
	The RPI is ignored at the IPv6 dst node.		The RPI is ignored at the RUL 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 RUL (Node G) and
	G) and inserts the RPI header (RPI), encapsulated in an IPv6-in-IPv6		inserts the RPI header (RPI), encapsulated in an IPv6-in-IPv6 header.
	header. The IPv6-in-IPv6 header is addressed hop-by-hop.		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.		for this use case.
			RFC XXXX RPL-data-plane August 2019
	+---------+------+-------+-------+---------+-------+-------+		+---------+------+-------+-------+---------+-------+-------+
	| Header | IPv6 | 6LR_1 | 6LR_ia| 6LBR |6LR_id | IPv6 |		| Header | RUL | 6LR_1 | 6LR_ia| 6LBR |6LR_id | RUL |
	| | src | | | | | dst |		| | src | | | | | dst |
	| | node | | | | | node |		| | node | | | | | node |
	+---------+------+-------+-------+---------+-------+-------+		+---------+------+-------+-------+---------+-------+-------+
	| Inserted| -- |IP6-IP6| -- | | -- | -- |		| Inserted| -- |IP6-IP6|IP6-IP6| IP6-IP6 |IP6-IP6| -- |
	| headers | | (RPI )| | | | |		| headers | | (RPI )| (RPI) | (RPI) | (RPI) | |
	| | | | | | | |		| | | | | | | |
	+---------+------+-------+-------+---------+-------+-------+		+---------+------+-------+-------+---------+-------+-------+
	| Removed | -- | -- | -- | | -- |IP6-IP6|		| Removed | -- | -- |IP6-IP6| IP6-IP6 |IP6-IP6|IP6-IP6|
	| headers | | | | | |(RPI) |		| headers | | | (RPI) | (RPI) | (RPI) |(RPI) |
	| | | | | | | RPI |		| | | | | | | RPI |
	| | | | | | |Ignored|		| | | | | | |Ignored|
	+---------+------+-------+-------+---------+-------+-------+		+---------+------+-------+-------+---------+-------+-------+
	| Re-added| -- | -- | -- | -- | -- | -- |		| Re-added| -- | -- | -- | -- | -- | -- |
	| headers | | | | | | |		| headers | | | | | | |
	+---------+------+-------+-------+---------+-------+-------+		+---------+------+-------+-------+---------+-------+-------+
	| Modified| -- | -- |IP6-IP6| IP6-IP6 |IP6-IP6| -- |		| Modified| -- | -- | | | | -- |
	| headers | | | (RPI) | (RPI) | (RPI) | |		| headers | | | | | | |
	| | | | | | | |		| | | | | | | |
	+---------+------+-------+-------+---------+-------+-------+		+---------+------+-------+-------+---------+-------+-------+
	|Untouched| -- | -- | -- | -- | -- | -- |		|Untouched| -- | -- | -- | -- | -- | -- |
	| headers | | | | | | |		| headers | | | | | | |
	+---------+------+-------+-------+---------+-------+-------+		+---------+------+-------+-------+---------+-------+-------+
	Figure 13: SM: Summary of the use of headers from RUL to RUL		Figure 13: SM: Summary of the use of headers from RUL to RUL
	8. 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 RPL-unaware
	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 table (Figure 14) summarizes what headers are needed in the
	the following scenarios, and indicates when the RPI, RH3 and IPv6-in-		following scenarios, and indicates when the RPI, RH3 and IPv6-in-IPv6
	IPv6 header are to be inserted. It depicts the target destination		header are to be inserted. It depicts the target destination address
	address possible (indicated by "RAL"), to a 6LR (parent of a 6LN) or		possible to a 6LN (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 6). In the table (Figure 14) the (1) indicates a 6tisch case
	where the RPI header may still be needed for the instanceID to be
	available for priority/channel selection at each hop.		RFC XXXX RPL-data-plane August 2019
			[RFC8180], where the RPI header may still be needed for the
			instanceID to be 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 |
	+-----------------+--------------+-----+-----+------------+------------+		+-----------------+--------------+-----+-----+------------+------------+
	| | RAL to root | Yes | No | No | No |		| | RAL to root | Yes | No | No | No |
	+ +--------------+-----+-----+------------+------------+		+ +--------------+-----+-----+------------+------------+
	| Leaf - Root | root to RAL | Yes | Yes | No | No |		| Leaf - Root | root to RAL | Yes | Yes | No | No |
	+ +--------------+-----+-----+------------+------------+		+ +--------------+-----+-----+------------+------------+
	| | root to RUL | Yes | Yes | must | 6LR |		| | root to RUL | Yes | Yes | must | 6LR |
	skipping to change at page 31, line 51 ¶		skipping to change at page 32, line 5 ¶
	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,
	RAL to root		RAL to root
	root to RAL		root to RAL
	RUL to root		RUL to root
			RFC XXXX RPL-data-plane August 2019
	root to RUL		root to RUL
	8.1.1. Non-SM: Example of Flow from RAL to root		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.
	RAL (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 are the intermediate routers from source to destination. In		6LR_i are the intermediate routers from source to destination. In
	this case, "1 <= i <= n", n is the number of routers (6LR) that the		this case, "1 <= i <= n", n is the number of routers (6LR) that the
	packet goes through from source (6LN) to destination (6LBR).		packet goes through from source (RAL) 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 | RAL 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-SM: Summary of the use of headers from RAL to root		Table 7: Non-SM: Summary of the use of headers from RAL to root
	skipping to change at page 32, line 47 ¶		skipping to change at page 32, line 51 ¶
	In this case the flow comprises:		In this case the flow comprises:
	root (6LBR) --> 6LR_i --> RAL (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 are the intermediate routers from source to destination. In		6LR_i are the intermediate routers from source to destination. In
	this case, "1 <= i <= n", n is the number of routers (6LR) that the		this case, "1 <= i <= n", n is the number of routers (6LR) that the
	packet goes through from source (6LBR) to destination (6LN).		packet goes through from source (6LBR) to destination (RAL).
	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.
			RFC XXXX RPL-data-plane August 2019
	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 | RAL 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-SM: Summary of the use of headers from root to RAL		Table 8: Non-SM: Summary of the use of headers from root to RAL
	8.1.3. Non-SM: Example of Flow from root to RUL		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 --> RUL (IPv6)		root (6LBR) --> 6LR_i --> RUL (IPv6 dst node)
	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 are the intermediate routers from source to destination. In		6LR_i are the intermediate routers from source to destination. In
	this case, "1 <= i <= n", n is the number of routers (6LR) that the		this case, "1 <= i <= n", n is the number of routers (6LR) that the
	packet goes through from source (6LBR) to destination (IPv6).		packet goes through from source (6LBR) to destination (RUL).
	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.
			RFC XXXX RPL-data-plane August 2019
	+-----------+----------+--------------+----------------+----------+		+-----------+----------+--------------+----------------+----------+
	| Header | 6LBR | 6LR_i | 6LR_n | IPv6 |		| Header | 6LBR | 6LR_i | 6LR_n | IPv6 |
	| | | i=(1,..,n-1) | | dst |		| | | i=(1,..,n-1) | |dst node |
	| | | | | node |		| | | | | (RUL) |
	+-----------+----------+--------------+----------------+----------+		+-----------+----------+--------------+----------------+----------+
	| Inserted | RPI, RH3 | -- | -- | -- |		| Inserted | RPI, RH3 | -- | -- | -- |
	| headers | | | | |		| headers | | | | |
	+-----------+----------+--------------+----------------+----------+		+-----------+----------+--------------+----------------+----------+
	| Removed | -- | -- | | -- |		| Removed | -- | -- | | -- |
	| headers | | | | |		| headers | | | | |
	+-----------+----------+--------------+----------------+----------+		+-----------+----------+--------------+----------------+----------+
	| Re-added | -- | -- | -- | -- |		| Re-added | -- | -- | -- | -- |
	| headers | | | | |		| headers | | | | |
	+-----------+----------+--------------+----------------+----------+		+-----------+----------+--------------+----------------+----------+
	skipping to change at page 34, line 33 ¶		skipping to change at page 34, line 35 ¶
	| headers | | | | (both |		| headers | | | | (both |
	| | | | | ignored) |		| | | | | ignored) |
	+-----------+----------+--------------+----------------+----------+		+-----------+----------+--------------+----------------+----------+
	Figure 15: Non-SM: Summary of the use of headers from root to RUL		Figure 15: Non-SM: Summary of the use of headers from root to RUL
	8.1.4. Non-SM: Example of Flow from RUL 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:
	RUL (IPv6) --> 6LR_1 --> 6LR_i --> root (6LBR)		RUL (IPv6 src node) --> 6LR_1 --> 6LR_i --> root (6LBR) 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 B --> Node A (root)
	6LR_i are the intermediate routers from source to destination. In		6LR_i are the intermediate routers from source to destination. In
	this case, "1 < i <= n", n is the number of routers (6LR) that the		this case, "1 <= i <= n", n is the number of routers (6LR) that the
	packet goes through from source (IPv6) to destination (6LBR). For		packet goes through from source (RUL) to destination (6LBR). For
	example, 6LR_1 (i=1) is the router that receives the packets from the		example, 6LR_1 (i=1) is the router that receives the packets from the
	IPv6 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 the 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.
			RFC XXXX RPL-data-plane August 2019
	+---------+----+-----------------+-----------------+-----------------+		+---------+----+-----------------+-----------------+-----------------+
	| Header |IPv6| 6LR_1 | 6LR_i | 6LBR dst |		| |RUL | | | |
	| |src | | | |		| Header |src | 6LR_1 | 6LR_i | 6LBR dst |
	| |node| | | |		| |node| | | |
	+---------+----+-----------------+-----------------+-----------------+		+---------+----+-----------------+-----------------+-----------------+
	| Inserted| -- |IPv6-in-IPv6(RPI)| -- | -- |		| Inserted| -- |IPv6-in-IPv6(RPI)| -- | -- |
	| headers | | | | |		| headers | | | | |
	+---------+----+-----------------+-----------------+-----------------+		+---------+----+-----------------+-----------------+-----------------+
	| Removed | -- | -- | -- |IPv6-in-IPv6(RPI)|		| Removed | -- | -- | -- |IPv6-in-IPv6(RPI)|
	| headers | | | | |		| headers | | | | |
	+---------+----+-----------------+-----------------+-----------------+		+---------+----+-----------------+-----------------+-----------------+
	| Re-added| -- | -- | -- | -- |		| Re-added| -- | -- | -- | -- |
	| headers | | | | |		| headers | | | | |
	skipping to change at page 35, line 45 ¶		skipping to change at page 35, line 47 ¶
	Internet to RAL		Internet to RAL
	RUL to Internet		RUL to Internet
	Internet to RUL		Internet to RUL
	8.2.1. Non-SM: Example of Flow from RAL 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:
	RAL (6LN) --> 6LR_i --> root (6LBR) --> Internet		RAL (6LN) src --> 6LR_i --> root (6LBR) --> Internet 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 --> Internet		Node B --> Node A --> Internet
	6LR_i are the intermediate routers from source to destination. In		6LR_i are the intermediate routers from source to destination. In
	this case, "1 <= i <= n", n is the number of routers (6LR) that the		this case, "1 <= i <= n", n is the number of routers (6LR) that the
	packet goes through from source (6LN) to 6LBR.		packet goes through from source (RAL) to 6LBR.
			RFC XXXX RPL-data-plane August 2019
	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		The IPv6 flow label should be set to zero to aid in compression
	[RFC8138], and the 6LBR will set it to a non-zero value when sending		[RFC8138], and the 6LBR will set it to a non-zero value when sending
	towards the Internet [RFC6437].		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 | RAL 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-SM: Summary of the use of headers from RAL to Internet		Table 9: Non-SM: Summary of the use of headers from RAL to Internet
	8.2.2. Non-SM: Example of Flow from Internet to RAL		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 --> RAL (6LN)		Internet --> root (6LBR) --> 6LR_i --> RAL dst (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 are the intermediate routers from source to destination. In		6LR_i are the intermediate routers from source to destination. In
	this case, "1 <= i <= n", n is the number of routers (6LR) that the		this case, "1 <= i <= n", n is the number of routers (6LR) that the
	packet goes through from 6LBR to destination(6LN).		packet goes through from 6LBR to destination (RAL).
	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 [RFC8138].		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.
			RFC XXXX RPL-data-plane August 2019
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	| Header | Internet | 6LBR | 6LR_i | 6LN src |		| Header | Internet | 6LBR | 6LR_i | RAL dst |
	| | dst | | | |		| | src | | | |
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	| 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-SM: Summary of the use of headers from Internet to RAL		Table 10: Non-SM: Summary of the use of headers from Internet to RAL
	8.2.3. Non-SM: Example of Flow from RUL 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:
	RUL (IPv6) --> 6LR_1 --> 6LR_i -->root (6LBR) --> Internet		RUL (IPv6 src node) --> 6LR_1 --> 6LR_i -->root (6LBR) --> Internet
			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 --> Internet		Node B --> Node A --> Internet
	6LR_i are the intermediate routers from source to destination. In		6LR_i are the intermediate routers from source to destination. In
	this case, "1 < i <= n", n is the number of routers (6LR) that the		this case, "1 <= i <= n", n is the number of routers (6LR) that the
	packet goes through from source(IPv6) to 6LBR. e.g 6LR_1 (i=1).		packet goes through from source (RUL) 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 7.2.3).		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.		for this use case.
			RFC XXXX RPL-data-plane August 2019
	+---------+----+-------------+--------------+--------------+--------+		+---------+----+-------------+--------------+--------------+--------+
	| Header |IPv6| 6LR_1 | 6LR_i | 6LBR |Internet|		| Header |RUL | 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) | -- |
	| headers | | | | | |		| headers | | | | | |
	+---------+----+-------------+--------------+--------------+--------+		+---------+----+-------------+--------------+--------------+--------+
	| Re-added| -- | -- | -- | -- | -- |		| Re-added| -- | -- | -- | -- | -- |
	skipping to change at page 38, line 32 ¶		skipping to change at page 38, line 34 ¶
	|Untouched| -- | -- | -- | -- | -- |		|Untouched| -- | -- | -- | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	+---------+----+-------------+--------------+--------------+--------+		+---------+----+-------------+--------------+--------------+--------+
	Figure 17: Non-SM: Summary of the use of headers from RUL to Internet		Figure 17: Non-SM: Summary of the use of headers from RUL to Internet
	8.2.4. Non-SM: Example of Flow from Internet to RUL		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 --> RUL (IPv6)		Internet src --> root (6LBR) --> 6LR_i --> RUL (IPv6 dst node)
	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 are the intermediate routers from source to destination. In		6LR_i are the intermediate routers from source to destination. In
	this case, "1 < i <= n", n is the number of routers (6LR) that the		this case, "1 <= i <= n", n is the number of routers (6LR) that the
	packet goes through from 6LBR to RUL (IPv6).		packet goes through from 6LBR to RUL.
	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 [RFC8138].		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.
			RFC XXXX RPL-data-plane August 2019
	+---------+--------+-------------+--------------+--------------+-----+		+---------+--------+-------------+--------------+--------------+-----+
	| Header |Internet| 6LBR | 6LR_1 | 6lR_i |IPv6 |		| Header |Internet| 6LBR | 6LR_1 | 6lR_i |RUL |
	| | src | | | (i=2,...,n) |dst |		| | src | | | (i=2,...,n) |dst |
	| | | | | |node |		| | | | | |node |
	+---------+--------+-------------+--------------+--------------+-----+		+---------+--------+-------------+--------------+--------------+-----+
	| 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)[1] | |		| headers | | | | (RH3,RPI)[1] | |
	+---------+--------+-------------+--------------+--------------+-----+		+---------+--------+-------------+--------------+--------------+-----+
	| Re-added| -- | -- | -- | -- | -- |		| Re-added| -- | -- | -- | -- | -- |
	skipping to change at page 39, line 46 ¶		skipping to change at page 39, line 48 ¶
	RAL to RUL		RAL to RUL
	RUL to RAL		RUL to RAL
	RUL to RUL		RUL to RUL
	8.3.1. Non-SM: Example of Flow from RAL to RAL		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		RAL src --> 6LR_ia --> root (6LBR) --> 6LR_id --> RAL 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
			RFC XXXX RPL-data-plane August 2019
	6LR_ia are the intermediate routers 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 packet		case, 1 <= ia <= n, n is the number of routers (6LR) that the packet
	goes through from 6LN to the root.		goes through from RAL to the root.
	6LR_id are the intermediate routers 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 (RPI1) into an IPv6-in-IPv6
	addressed to the root, so that the 6LBR can remove that header. If		header addressed to the root, so that the 6LBR can remove that
	it does not, then additional resources are wasted on the way down to		header. If it does not, then additional resources are wasted on the
	carry the useless RPI option.		way down to 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
	it was contained in an IPv6-in-IPv6 header addressed to it.		RPI(RPI1), as it was contained in an IPv6-in-IPv6 header addressed to
	Otherwise, there may be a RPI header buried inside the inner IP		it. Otherwise, there may be a RPI header buried inside the inner IP
	header, which should get ignored.		header, which should get ignored. The root inserts a RPI (RPI2)
			alongside the RH3.
	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 8.1.2, 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.
			RFC XXXX RPL-data-plane August 2019
	+---------+------------+----------+------------+----------+------------+		+---------+------------+----------+------------+----------+------------+
	| Header | 6LN | 6LR_ia | 6LBR | 6LR_id | 6LN |		| Header | RAL | 6LR_ia | 6LBR | 6LR_id | RAL |
	| | 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-> RAL, | | |
	| | | | RPI2) | | |		| | | | RPI2) | | |
	+---------+------------+----------+------------+----------+------------+		+---------+------------+----------+------------+----------+------------+
	| Removed | -- | -- |IPv6-in-IPv6| -- |IPv6-in-IPv6|		| Removed | -- | -- |IPv6-in-IPv6| -- |IPv6-in-IPv6|
	| headers | | | (RPI1) | | (RH3, |		| headers | | | (RPI1) | | (RH3, |
	| | | | | | RPI2) |		| | | | | | RPI2) |
	+---------+------------+----------+------------+----------+------------+		+---------+------------+----------+------------+----------+------------+
	| Re-added| -- | -- | -- | -- | -- |		| Re-added| -- | -- | -- | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	+---------+------------+----------+------------+----------+------------+		+---------+------------+----------+------------+----------+------------+
	| Modified| -- |IP6-in-IP6| -- |IP6-in-IP6| -- |		| Modified| -- |IP6-in-IP6| -- |IP6-in-IP6| -- |
	skipping to change at page 41, line 34 ¶		skipping to change at page 41, line 36 ¶
	| headers | | | | | |		| headers | | | | | |
	+---------+------------+----------+------------+----------+------------+		+---------+------------+----------+------------+----------+------------+
	Figure 19: Non-SM: Summary of the use of headers for RAL to RAL.		Figure 19: Non-SM: Summary of the use of headers for RAL to RAL.
	IP6-in-IP6 refers to IPv6-in-IPv6.		IP6-in-IP6 refers to IPv6-in-IPv6.
	8.3.2. Non-SM: Example of Flow from RAL to RUL		8.3.2. Non-SM: Example of Flow from RAL to RUL
	In this case the flow comprises:		In this case the flow comprises:
	6LN --> 6LR_ia --> root (6LBR) --> 6LR_id --> not-RPL-aware (IPv6)		RAL --> 6LR_ia --> root (6LBR) --> 6LR_id --> RUL (IPv6 dst node)
	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 are the intermediate routers 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 are the intermediate routers 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 RAL (6LN) will insert a RPI (RPI_1)
	which must be in an IPv6-in-IPv6 header addressed to the root so that		header which must be in an IPv6-in-IPv6 header addressed to the root
	the 6LBR can remove this RPI. The 6LBR will then insert an RH3		so that the 6LBR can remove this RPI. The 6LBR will then insert an
	inside a new IPv6-in-IPv6 header addressed to the 6LR_id.		RH3 inside a new IPv6-in-IPv6 header addressed to the last 6LR_id
			(6LR_id = m).
			RFC XXXX RPL-data-plane August 2019
	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.		for this use case.
	+-----------+---------+---------+---------+---------+---------+------+		+-----------+---------+---------+---------+---------+---------+------+
	| Header | 6LN | 6LR_ia | 6LBR | 6LR_id | 6LR_m | IPv6 |		| Header | RAL | 6LR_ia | 6LBR | 6LR_id | 6LR_m | RUL |
	| | src | | | | | dst |		| | src | | | | | dst |
	| | | | | | | node |		| | node | | | | | node |
	+-----------+---------+---------+---------+---------+---------+------+		+-----------+---------+---------+---------+---------+---------+------+
	| Inserted | IP6-IP6 | | IP6-IP6 | -- | -- | -- |		| Inserted | IP6-IP6 | | IP6-IP6 | -- | -- | -- |
	| headers | (RPI1) | | (RH3, | | | |		| headers | (RPI1) | | (RH3, | | | |
	| | | | RPI2) | | | |		| | | | RPI2) | | | |
	+-----------+---------+---------+---------+---------+---------+------+		+-----------+---------+---------+---------+---------+---------+------+
	| Removed | -- | -- | IP6-IP6 | -- | IP6-IP6 | -- |		| Removed | -- | -- | IP6-IP6 | -- | IP6-IP6 | -- |
	| headers | | | (RPI1) | | (RH3, | |		| headers | | | (RPI1) | | (RH3, | |
	| | | | | | RPI2) | |		| | | | | | RPI2) | |
	+-----------+---------+---------+---------+---------+---------+------+		+-----------+---------+---------+---------+---------+---------+------+
	| Re-added | -- | -- | -- | -- | -- | -- |		| Re-added | -- | -- | -- | -- | -- | -- |
	skipping to change at page 42, line 35 ¶		skipping to change at page 42, line 40 ¶
	| Untouched | -- | -- | -- | -- | -- | -- |		| Untouched | -- | -- | -- | -- | -- | -- |
	| headers | | | | | | |		| headers | | | | | | |
	+-----------+---------+---------+---------+---------+---------+------+		+-----------+---------+---------+---------+---------+---------+------+
	Figure 20: Non-SM: Summary of the use of headers from RAL to RUL.		Figure 20: Non-SM: Summary of the use of headers from RAL to RUL.
	8.3.3. Non-SM: Example of Flow from RUL to RAL		8.3.3. Non-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_1 --> 6LR_ia --> root (6LBR) -->		RUL (IPv6 src node) --> 6LR_1 --> 6LR_ia --> root (6LBR) --> 6LR_id
	6LR_id --> 6LN		--> RAL dst (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 are the intermediate routers 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 are the intermediate routers 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
	added by the first 6LR (6LR_1) inside an IPv6-in-IPv6 header		(RPI1) is added by the first 6LR (6LR_1) inside an IPv6-in-IPv6
	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).		RFC XXXX RPL-data-plane August 2019
			header 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
			(RPI2).
	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.		for this use case.
	+-----------+------+---------+---------+---------+---------+---------+		+-----------+------+---------+---------+---------+---------+---------+
	| Header | IPv6 | 6LR_1 | 6LR_ia | 6LBR | 6LR_id | 6LN |		| Header | RUL | 6LR_1 | 6LR_ia | 6LBR | 6LR_id | RAL |
	| | src | | | | | dst |		| | src | | | | | dst |
	| | node | | | | | |		| | node | | | | | node |
	+-----------+------+---------+---------+---------+---------+---------+		+-----------+------+---------+---------+---------+---------+---------+
	| Inserted | -- | IP6-IP6 | -- | IP6-IP6 | -- | -- |		| Inserted | -- | IP6-IP6 | -- | IP6-IP6 | -- | -- |
	| headers | | (RPI1) | | (RH3, | | |		| headers | | (RPI1) | | (RH3, | | |
	| | | | | RPI2) | | |		| | | | | RPI2) | | |
	+-----------+------+---------+---------+---------+---------+---------+		+-----------+------+---------+---------+---------+---------+---------+
	| Removed | -- | | -- | IP6-IP6 | -- | IP6-IP6 |		| Removed | -- | | -- | IP6-IP6 | -- | IP6-IP6 |
	| headers | | | | (RPI1) | | (RH3, |		| headers | | | | (RPI1) | | (RH3, |
	| | | | | | | RPI2) |		| | | | | | | RPI2) |
	+-----------+------+---------+---------+---------+---------+---------+		+-----------+------+---------+---------+---------+---------+---------+
	| Re-added | -- | | -- | -- | -- | -- |		| Re-added | -- | | -- | -- | -- | -- |
	skipping to change at page 43, line 38 ¶		skipping to change at page 43, line 44 ¶
	| Untouched | -- | | -- | -- | -- | -- |		| Untouched | -- | | -- | -- | -- | -- |
	| headers | | | | | | |		| headers | | | | | | |
	+-----------+------+---------+---------+---------+---------+---------+		+-----------+------+---------+---------+---------+---------+---------+
	Figure 21: Non-SM: Summary of the use of headers from RUL to RAL.		Figure 21: Non-SM: Summary of the use of headers from RUL to RAL.
	8.3.4. Non-SM: Example of Flow from RUL to RUL		8.3.4. Non-SM: Example of Flow from RUL to RUL
	In this case the flow comprises:		In this case the flow comprises:
	not-RPL-aware 6LN (IPv6 src) --> 6LR_1 --> 6LR_ia --> root (6LBR) -->		RUL (IPv6 src node) --> 6LR_1 --> 6LR_ia --> root (6LBR) --> 6LR_id
	6LR_id --> not-RPL-aware (IPv6 dst)		--> RUL (IPv6 dst node)
	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 are the intermediate routers 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)
			RFC XXXX RPL-data-plane August 2019
	6LR_id are the intermediate routers 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.		for this use case.
	+---------+------+-------+-------+---------+-------+---------+------+		+---------+------+-------+-------+---------+-------+---------+------+
	| Header | IPv6 | 6LR_1 | 6LR_ia| 6LBR |6LR_id | 6LR_m | IPv6 |		| Header | RUL | 6LR_1 | 6LR_ia| 6LBR |6LR_id | 6LR_m | RUL |
	| | 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) | | | |
	+---------+------+-------+-------+---------+-------+---------+------+		+---------+------+-------+-------+---------+-------+---------+------+
	| Removed | -- | -- | -- | IP6-IP6 | -- | IP6-IP6 | -- |		| Removed | -- | -- | -- | IP6-IP6 | -- | IP6-IP6 | -- |
	| headers | | | | (RPI1) | | (RH3, | |		| headers | | | | (RPI1) | | (RH3, | |
	| | | | | | | RPI2) | |		| | | | | | | RPI2) | |
	+---------+------+-------+-------+---------+-------+---------+------+		+---------+------+-------+-------+---------+-------+---------+------+
	skipping to change at page 44, line 34 ¶		skipping to change at page 44, line 42 ¶
	| 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-SM: Summary of the use of headers from RUL to RUL		Figure 22: Non-SM: Summary of the use of headers from RUL to RUL
	9. Operational Considerations of supporting not-RPL-aware-leaves		9. Operational Considerations of supporting RUL-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.
	Despite this, and despite the switch from 0x63 to 0x23, there may be		Despite this, and despite the switch from 0x63 to 0x23, there may be
	hosts that are pre-RFC8200, or simply intolerant. Those hosts will		hosts that are pre-RFC8200, or simply intolerant. Those hosts will
			RFC XXXX RPL-data-plane August 2019
	drop packets that continue to have RPL artifacts in them. In		drop packets that continue to have RPL artifacts in them. In
	general, such hosts can not be easily supported in RPL LLNs.		general, such hosts can not be easily supported in RPL LLNs.
	There are some specific cases where it is possible to remove the RPL		There are some specific cases where it is possible to remove the RPL
	artifacts prior to forwarding the packet to the leaf host. The		artifacts prior to forwarding the packet to the leaf host. The
	critical thing is that the artifacts have been inserted by the RPL		critical thing is that the artifacts have been inserted by the RPL
	root inside an IPv6-in-IPv6 header, and that the header has been		root inside an IPv6-in-IPv6 header, and that the header has been
	addressed to the 6LR immediately prior to the leaf node. In that		addressed to the 6LR immediately prior to the leaf node. In that
	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.
	skipping to change at page 45, line 45 ¶		skipping to change at page 46, line 4 ¶
	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
			RFC XXXX RPL-data-plane August 2019
	Option Type. Thus, the DIO is sent with a flag indicating the new		Option Type. Thus, the DIO is sent with a flag indicating the new
	RPI value.		RPI value.
	The DODAG Configuration option is contained in a RPL DIO message,		The DODAG Configuration option is contained in a RPL DIO message,
	which contains a unique DTSN counter. The leaf nodes respond to this		which contains a unique DTSN counter. The leaf nodes respond to this
	message with DAO messages containing the same DTSN. This is a normal		message with DAO messages containing the same DTSN. This is a normal
	part of RPL routing; the RPL root therefore knows when the updated		part of RPL routing; the RPL root therefore knows when the updated
	DODAG Configuration Option has been seen by all nodes.		DODAG Configuration Option has been seen by all nodes.
	Before the migration happens, all the RPL-aware nodes should support		Before the migration happens, all the RPL-aware nodes should support
	skipping to change at page 46, line 42 ¶		skipping to change at page 47, line 5 ¶
	| 0x23 | 00 | 1 | 00011 | RPL Option |[RFCXXXX](*)|		| 0x23 | 00 | 1 | 00011 | RPL Option |[RFCXXXX](*)|
	+-------+-----+-----+-------+------------------------+------------+		+-------+-----+-----+-------+------------------------+------------+
	| 0x63 | 01 | 1 | 00011 | RPL Option(DEPRECATED) | [RFC6553] |		| 0x63 | 01 | 1 | 00011 | RPL Option(DEPRECATED) | [RFC6553] |
	| | | | | |[RFCXXXX](*)|		| | | | | |[RFCXXXX](*)|
	+-------+-----+-----+-------+------------------------+------------+		+-------+-----+-----+-------+------------------------+------------+
	Figure 23: Option Type in RPL Option.(*)represents this document		Figure 23: Option Type in RPL Option.(*)represents this document
	DODAG Configuration option is updated as follows (Figure 24):		DODAG Configuration option is updated as follows (Figure 24):
			RFC XXXX RPL-data-plane August 2019
	+------------+-----------------+---------------+		+------------+-----------------+---------------+
	| 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.
	12. Security Considerations		12. Security Considerations
	skipping to change at page 47, line 21 ¶		skipping to change at page 47, line 32 ¶
	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 attack is targeting another LLN.		impact, particularly if attack is targeting another 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 [AUTONOMIC-CONTROL], which may be equipped with multiple
	equipped with multiple 100Gb/s interfaces.		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
	involves a single prefix comparison and should be trivial to		involves a single prefix comparison and should be trivial to
	automatically configure.		automatically configure.
	There are some scenarios where IPv6-in-IPv6 traffic should be allowed		There are some scenarios where IPv6-in-IPv6 traffic should be allowed
	to pass through the RPL root, such as the IPv6-in-IPv6 mediated		to pass through the RPL root, such as the IPv6-in-IPv6 mediated
	communications between a new Pledge and the Join Registrar/		communications between a new Pledge and the Join Registrar/
	Coordinator (JRC) when using [I-D.ietf-anima-bootstrapping-keyinfra]		Coordinator (JRC) when using [BRSKI] and
	and [I-D.ietf-6tisch-dtsecurity-secure-join]. This is the case for		[I-D.ietf-6tisch-dtsecurity-secure-join]. This is the case for the
	the RPL root to do careful filtering: it occurs only when the Join		RPL root to do careful filtering: it occurs only when the Join
	Coordinator is not co-located inside the RPL root.		Coordinator is not co-located inside the RPL root.
			RFC XXXX RPL-data-plane August 2019
	With the above precautions, an attack using IPv6-in-IPv6 tunnels can		With the above precautions, an attack using IPv6-in-IPv6 tunnels can
	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
	skipping to change at page 48, line 42 ¶		skipping to change at page 49, line 4 ¶
	(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
	attacker's RH3 header will not be seen by the network until it		attacker's RH3 header will not be seen by the network until it
	reaches the end host, which will decapsulate it. An end-host should		reaches the end host, which will decapsulate it. An end-host should
	be suspicious about a RH3 header which has additional hops which have		be suspicious about a RH3 header which has additional hops which have
	not yet been processed, and SHOULD ignore such a second RH3 header.		not yet been processed, and SHOULD ignore such a second RH3 header.
	In addition, the LLN will likely use [RFC8138] to compress the IPv6-		In addition, the LLN will likely use [RFC8138] to compress the IPv6-
	in-IPv6 and RH3 headers. As such, the compressor at the RPL-root		in-IPv6 and RH3 headers. As such, the compressor at the RPL-root
	will see the second RH3 header and MAY choose to discard the packet		will see the second RH3 header and MAY choose to discard the packet
			RFC XXXX RPL-data-plane August 2019
	if the RH3 header has not been completely consumed. A consumed		if the RH3 header has not been completely consumed. A consumed
	(inert) RH3 header could be present in a packet that flows from one		(inert) RH3 header could be present in a packet that flows from one
	LLN, crosses the Internet, and enters another LLN. As per the		LLN, crosses the Internet, and enters another LLN. As per the
	discussion in this document, such headers do not need to be removed.		discussion in this document, such headers do not need to be removed.
	However, there is no case described in this document where an RH3 is		However, there is no case described in this document where an RH3 is
	inserted in a non-storing network on traffic that is leaving the LLN,		inserted in a non-storing network on traffic that is leaving the LLN,
	but this document should not preclude such a future innovation. It		but this document should not preclude such a future innovation. It
	should just be noted that an incoming RH3 must be fully consumed, or		should just be noted that an incoming RH3 must be fully consumed, or
	very carefully inspected.		very carefully inspected.
	skipping to change at page 49, line 37 ¶		skipping to change at page 49, line 49 ¶
	Nodes within the LLN can use the IPv6-in-IPv6 mechanism to mount an		Nodes within the LLN can use the IPv6-in-IPv6 mechanism to mount an
	attack on another part of the LLN, while disguising the origin of the		attack on another part of the LLN, while disguising the origin of the
	attack. The mechanism can even be abused to make it appear that the		attack. The mechanism can even be abused to make it appear that the
	attack is coming from outside the LLN, and unless countered, this		attack is coming from outside the LLN, and unless countered, this
	could be used to mount a Distributed Denial Of Service attack upon		could be used to mount a Distributed Denial Of Service attack upon
	nodes elsewhere in the Internet. See [DDOS-KREBS] for an example of		nodes elsewhere in the Internet. See [DDOS-KREBS] for an example of
	such attacks already seen in the real world.		such attacks already seen in the real world.
	If an attack comes from inside of LLN, it can be alleviated with SAVI		If an attack comes from inside of LLN, it can be alleviated with SAVI
	(Source Address Validation Improvement) using [RFC8505] with		(Source Address Validation Improvement) using [RFC8505] with [AP-ND].
	[I-D.ietf-6lo-ap-nd]. The attacker will not be able to source		The attacker will not be able to source traffic with an address that
	traffic with an address that is not registered, and the registration		is not registered, and the registration process checks for
	process checks for topological correctness. Notice that there is an		topological correctness. Notice that there is an L2 authentication
	L2 authentication in most of the cases. If an attack comes from		in most of the cases. If an attack comes from outside LLN IPv6-in-
	outside LLN IPv6-in- IPv6 can be used to hide inner routing headers,		IPv6 can be used to hide inner routing headers, but by construction,
	but by construction, the RH3 can typically only address nodes within
	the LLN. That is, a RH3 with a CmprI less than 8 , should be		RFC XXXX RPL-data-plane August 2019
	considered an attack (see RFC6554, section 3).
			the RH3 can typically only address nodes within the LLN. That is, a
			RH3 with a CmprI less than 8 , should be considered an attack (see
			RFC6554, section 3).
	Nodes outside of the LLN will need to pass IPv6-in-IPv6 traffic		Nodes outside of the LLN will need to pass IPv6-in-IPv6 traffic
	through the RPL root to perform this attack. To counter, the RPL		through the RPL root to perform this attack. To counter, the RPL
	root SHOULD either restrict ingress of IPv6-in-IPv6 packets (the		root SHOULD either restrict ingress of IPv6-in-IPv6 packets (the
	simpler solution), or it SHOULD walk the IP header extension chain		simpler solution), or it SHOULD walk the IP header extension chain
	until it can inspect the upper-layer-payload as described in		until it can inspect the upper-layer-payload as described in
	[RFC7045]. In particular, the RPL root SHOULD do [BCP38] processing		[RFC7045]. In particular, the RPL root SHOULD do [BCP38] processing
	on the source addresses of all IP headers that it examines in both		on the source addresses of all IP headers that it examines in both
	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.
	13. Acknowledgments		13. Acknowledgments
	This work is done thanks to the grant by the Stand.ICT project.		This work is done thanks to the grant given by the StandICT.eu
			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 4. 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 Gundogan, Rahul Jadhav, Benjamin Kaduk,
	Kovatsch, Peter van der Stok, Xavier Vilajosana and Thomas Watteyne.		Matthias Kovatsch, Charlie Perkins, Alvaro Retana, Peter van der
			Stok, Xavier Vilajosana, Eric Vyncke and Thomas Watteyne.
	14. References		14. References
	14.1. 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/rfc2827>.
			RFC XXXX RPL-data-plane August 2019
	[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>.
	[RFC6040] Briscoe, B., "Tunnelling of Explicit Congestion		[RFC6040] Briscoe, B., "Tunnelling of Explicit Congestion
	Notification", RFC 6040, DOI 10.17487/RFC6040, November		Notification", RFC 6040, DOI 10.17487/RFC6040, November
	2010, <https://www.rfc-editor.org/info/rfc6040>.		2010, <https://www.rfc-editor.org/info/rfc6040>.
	skipping to change at page 51, line 39 ¶		skipping to change at page 52, line 5 ¶
	[RFC8025] Thubert, P., Ed. and R. Cragie, "IPv6 over Low-Power		[RFC8025] Thubert, P., Ed. and R. Cragie, "IPv6 over Low-Power
	Wireless Personal Area Network (6LoWPAN) Paging Dispatch",		Wireless Personal Area Network (6LoWPAN) Paging Dispatch",
	RFC 8025, DOI 10.17487/RFC8025, November 2016,		RFC 8025, DOI 10.17487/RFC8025, November 2016,
	<https://www.rfc-editor.org/info/rfc8025>.		<https://www.rfc-editor.org/info/rfc8025>.
	[RFC8138] Thubert, P., Ed., Bormann, C., Toutain, L., and R. Cragie,		[RFC8138] Thubert, P., Ed., Bormann, C., Toutain, L., and R. Cragie,
	"IPv6 over Low-Power Wireless Personal Area Network		"IPv6 over Low-Power Wireless Personal Area Network
	(6LoWPAN) Routing Header", RFC 8138, DOI 10.17487/RFC8138,		(6LoWPAN) Routing Header", RFC 8138, DOI 10.17487/RFC8138,
	April 2017, <https://www.rfc-editor.org/info/rfc8138>.		April 2017, <https://www.rfc-editor.org/info/rfc8138>.
			RFC XXXX RPL-data-plane August 2019
	[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>.
	14.2. Informative References		14.2. Informative References
			[AP-ND] Thubert, P., Sarikaya, B., Sethi, M., and R. Struik,
			"Address Protected Neighbor Discovery for Low-power and
			Lossy Networks", Work in Progress, draft-ietf-6lo-ap-nd-
			12, April 2019.
			[AUTONOMIC-CONTROL]
			Eckert, T., Behringer, M., and S. Bjarnason, "An Autonomic
			Control Plane (ACP)", Work in Progress, draft-ietf-anima-
			autonomic-control-plane-20, July 2019.
			[BRSKI] Pritikin, M., Richardson, M., Behringer, M., and K.
			Watsen, "Bootstrapping Remote Secure Key Infrastructures
			(BRSKI)", Work in Progress, draft-ietf-anima-
			bootstrapping-keyinfra-24, July 2019.
	[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]
	Thubert, P., Sarikaya, B., Sethi, M., and R. Struik,
	"Address Protected Neighbor Discovery for Low-power and
	Lossy Networks", draft-ietf-6lo-ap-nd-12 (work in
	progress), April 2019.
	[I-D.ietf-6lo-backbone-router]		[I-D.ietf-6lo-backbone-router]
	Thubert, P., Perkins, C., and E. Levy-Abegnoli, "IPv6		Thubert, P., Perkins, C., and E. Levy-Abegnoli, "IPv6
	Backbone Router", draft-ietf-6lo-backbone-router-11 (work		Backbone Router", draft-ietf-6lo-backbone-router-11 (work
	in progress), February 2019.		in progress), February 2019.
	[I-D.ietf-6tisch-dtsecurity-secure-join]		[I-D.ietf-6tisch-dtsecurity-secure-join]
	Richardson, M., "6tisch Secure Join protocol", draft-ietf-		Richardson, M., "6tisch Secure Join protocol", draft-ietf-
	6tisch-dtsecurity-secure-join-01 (work in progress),		6tisch-dtsecurity-secure-join-01 (work in progress),
	February 2017.		February 2017.
	[I-D.ietf-anima-autonomic-control-plane]		[IP-TUNNELS]
	Eckert, T., Behringer, M., and S. Bjarnason, "An Autonomic
	Control Plane (ACP)", draft-ietf-anima-autonomic-control-
	plane-19 (work in progress), March 2019.
	[I-D.ietf-anima-bootstrapping-keyinfra]
	Pritikin, M., Richardson, M., Behringer, M., Bjarnason,
	S., and K. Watsen, "Bootstrapping Remote Secure Key
	Infrastructures (BRSKI)", draft-ietf-anima-bootstrapping-
	keyinfra-22 (work in progress), June 2019.
	[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", Work in Progress, draft-ietf-intarea-
	progress), July 2018.		tunnels-09, July 2018.
	[I-D.thubert-roll-unaware-leaves]		RFC XXXX RPL-data-plane August 2019
	Thubert, P., "Routing for RPL Leaves", draft-thubert-roll-
	unaware-leaves-07 (work in progress), April 2019.
	[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6		[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
	(IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460,		(IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460,
	December 1998, <https://www.rfc-editor.org/info/rfc2460>.		December 1998, <https://www.rfc-editor.org/info/rfc2460>.
	[RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in		[RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in
	IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473,		IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473,
	December 1998, <https://www.rfc-editor.org/info/rfc2473>.		December 1998, <https://www.rfc-editor.org/info/rfc2473>.
	[RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet		[RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet
	skipping to change at page 53, line 46 ¶		skipping to change at page 54, line 5 ¶
	[RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and		[RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and
	Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January		Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January
	2014, <https://www.rfc-editor.org/info/rfc7102>.		2014, <https://www.rfc-editor.org/info/rfc7102>.
	[RFC7416] Tsao, T., Alexander, R., Dohler, M., Daza, V., Lozano, A.,		[RFC7416] Tsao, T., Alexander, R., Dohler, M., Daza, V., Lozano, A.,
	and M. Richardson, Ed., "A Security Threat Analysis for		and M. Richardson, Ed., "A Security Threat Analysis for
	the Routing Protocol for Low-Power and Lossy Networks		the Routing Protocol for Low-Power and Lossy Networks
	(RPLs)", RFC 7416, DOI 10.17487/RFC7416, January 2015,		(RPLs)", RFC 7416, DOI 10.17487/RFC7416, January 2015,
	<https://www.rfc-editor.org/info/rfc7416>.		<https://www.rfc-editor.org/info/rfc7416>.
			RFC XXXX RPL-data-plane August 2019
	[RFC8180] Vilajosana, X., Ed., Pister, K., and T. Watteyne, "Minimal		[RFC8180] Vilajosana, X., Ed., Pister, K., and T. Watteyne, "Minimal
	IPv6 over the TSCH Mode of IEEE 802.15.4e (6TiSCH)		IPv6 over the TSCH Mode of IEEE 802.15.4e (6TiSCH)
	Configuration", BCP 210, RFC 8180, DOI 10.17487/RFC8180,		Configuration", BCP 210, RFC 8180, DOI 10.17487/RFC8180,
	May 2017, <https://www.rfc-editor.org/info/rfc8180>.		May 2017, <https://www.rfc-editor.org/info/rfc8180>.
	[RFC8505] Thubert, P., Ed., Nordmark, E., Chakrabarti, S., and C.		[RFC8505] Thubert, P., Ed., Nordmark, E., Chakrabarti, S., and C.
	Perkins, "Registration Extensions for IPv6 over Low-Power		Perkins, "Registration Extensions for IPv6 over Low-Power
	Wireless Personal Area Network (6LoWPAN) Neighbor		Wireless Personal Area Network (6LoWPAN) Neighbor
	Discovery", RFC 8505, DOI 10.17487/RFC8505, November 2018,		Discovery", RFC 8505, DOI 10.17487/RFC8505, November 2018,
	<https://www.rfc-editor.org/info/rfc8505>.		<https://www.rfc-editor.org/info/rfc8505>.
			[RPL-LEAVES]
			Thubert, P., "Routing for RPL Leaves", Work in Progress,
			draft-ietf-roll-unaware-leaves-02, July 2019.
	Authors' Addresses		Authors' Addresses
	Maria Ines Robles		Maria Ines Robles
	Aalto University		Aalto University, Finland - / - Universidad Tecnologica Nacional - Facultad Regional Mendoza, Argentina
	Otaniemi
	Espoo 02150
	Finland
	Email: mariainesrobles@gmail.com		Email: mariainesrobles@gmail.com
	Michael C. Richardson		Michael C. Richardson
	Sandelman Software Works		Sandelman Software Works
	470 Dawson Avenue		470 Dawson Avenue
	Ottawa, ON K1Z 5V7		Ottawa, ON K1Z 5V7
	CA		CA
	Email: mcr+ietf@sandelman.ca		Email: mcr+ietf@sandelman.ca
	URI: http://www.sandelman.ca/mcr/		URI: http://www.sandelman.ca/mcr/
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