< draft-ietf-roll-useofrplinfo-25.txt		draft-ietf-roll-useofrplinfo-26.txt >
	ROLL Working Group M. Robles		ROLL Working Group M. Robles
	Internet-Draft Aalto		Internet-Draft Aalto
	Updates: 6553, 6550, 8138 (if approved) M. Richardson		Updates: 6553, 6550, 8138 (if approved) M. Richardson
	Intended status: Standards Track SSW		Intended status: Standards Track SSW
	Expires: September 12, 2019 P. Thubert		Expires: November 16, 2019 P. Thubert
	Cisco		Cisco
	March 11, 2019		May 15, 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-25		draft-ietf-roll-useofrplinfo-26
	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 RFC 6553 (RPL Option Type), RFC 6554		enumerates the cases where RFC 6553 (RPL Option Type), RFC 6554
	(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
	RFC 6553 adding a change to the RPL Option Type. Additionally, this		RFC 6553 adding a change to the RPL Option Type. Additionally, this
	document updates RFC 6550 to indicate about this change and updates		document updates RFC 6550 defining a flag in the DIO Configuration
	RFC8138 as well to consider the new Option Type when RPL Option is		Option to indicate about this change and updates RFC8138 as well to
	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 Internet-Draft is submitted in full conformance with the
	provisions of BCP 78 and BCP 79.		provisions of BCP 78 and BCP 79.
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at https://datatracker.ietf.org/drafts/current/.		Drafts is at https://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	This Internet-Draft will expire on September 12, 2019.		This Internet-Draft will expire on November 16, 2019.
	Copyright Notice		Copyright Notice
	Copyright (c) 2019 IETF Trust and the persons identified as the		Copyright (c) 2019 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
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	(https://trustee.ietf.org/license-info) in effect on the date of		(https://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	described in the Simplified BSD License.		described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
	1.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 4		1.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 4
	2. Terminology and Requirements Language . . . . . . . . . . . . 4		2. Terminology and Requirements Language . . . . . . . . . . . . 5
	3. Updates to RFC6553, RFC6550 and RFC 8138 . . . . . . . . . . 5		3. Updates to RFC6553, RFC6550 and RFC8138 . . . . . . . . . . . 6
	3.1. Updates to RFC 6553 . . . . . . . . . . . . . . . . . . . 5		3.1. Updates to RFC6553: Indicating the new RPI value. . . . . 6
	3.2. Updates to RFC 8138 . . . . . . . . . . . . . . . . . . . 8		3.2. Updates to RFC6550: Indicating the new RPI in the
	3.3. Updates to RFC 6550: Indicating the new RPI in the		DODAG Configuration Option Flag. . . . . . . . . . . . . 10
	DODAG Configuration Option Flag. . . . . . . . . . . . . 8		3.3. Updates to RFC8138: Indicating the way to decompress with
	4. Sample/reference topology . . . . . . . . . . . . . . . . . . 9		the new RPI value. . . . . . . . . . . . . . . . . . . . 11
	5. Use cases . . . . . . . . . . . . . . . . . . . . . . . . . . 12		4. Sample/reference topology . . . . . . . . . . . . . . . . . . 11
	6. Storing mode . . . . . . . . . . . . . . . . . . . . . . . . 15		5. Use cases . . . . . . . . . . . . . . . . . . . . . . . . . . 14
	6.1. Storing Mode: Interaction between Leaf and Root . . . . . 16		6. Storing mode . . . . . . . . . . . . . . . . . . . . . . . . 16
			6.1. Storing Mode: Interaction between Leaf and Root . . . . . 17
	6.1.1. SM: Example of Flow from RPL-aware-leaf to root . . . 17		6.1.1. SM: Example of Flow from RPL-aware-leaf to root . . . 17
	6.1.2. SM: Example of Flow from root to RPL-aware-leaf . . . 18		6.1.2. SM: Example of Flow from root to RPL-aware-leaf . . . 19
	6.1.3. SM: Example of Flow from root to not-RPL-aware-leaf . 18		6.1.3. SM: Example of Flow from root to not-RPL-aware-leaf . 19
	6.1.4. SM: Example of Flow from not-RPL-aware-leaf to root . 19		6.1.4. SM: Example of Flow from not-RPL-aware-leaf to root . 20
	6.2. Storing Mode: Interaction between Leaf and Internet. . . 20		6.2. Storing Mode: Interaction between Leaf and Internet. . . 21
	6.2.1. SM: Example of Flow from RPL-aware-leaf to Internet . 20		6.2.1. SM: Example of Flow from RPL-aware-leaf to Internet . 21
	6.2.2. SM: Example of Flow from Internet to RPL-aware-leaf . 21		6.2.2. SM: Example of Flow from Internet to RPL-aware-leaf . 22
	6.2.3. SM: Example of Flow from not-RPL-aware-leaf to		6.2.3. SM: Example of Flow from not-RPL-aware-leaf to
	Internet . . . . . . . . . . . . . . . . . . . . . . 22		Internet . . . . . . . . . . . . . . . . . . . . . . 23
	6.2.4. SM: Example of Flow from Internet to non-RPL-aware-		6.2.4. SM: Example of Flow from Internet to not-RPL-aware-
	leaf. . . . . . . . . . . . . . . . . . . . . . . . . 23		leaf. . . . . . . . . . . . . . . . . . . . . . . . . 24
	6.3. Storing Mode: Interaction between Leaf and Leaf . . . . . 24		6.3. Storing Mode: Interaction between Leaf and Leaf . . . . . 25
	6.3.1. SM: Example of Flow from RPL-aware-leaf to RPL-aware-		6.3.1. SM: Example of Flow from RPL-aware-leaf to RPL-aware-
	leaf . . . . . . . . . . . . . . . . . . . . . . . . 24		leaf . . . . . . . . . . . . . . . . . . . . . . . . 25
	6.3.2. SM: Example of Flow from RPL-aware-leaf to non-RPL-		6.3.2. SM: Example of Flow from RPL-aware-leaf to not-RPL-
	aware-leaf . . . . . . . . . . . . . . . . . . . . . 26		aware-leaf . . . . . . . . . . . . . . . . . . . . . 26
	6.3.3. SM: Example of Flow from not-RPL-aware-leaf to RPL-		6.3.3. SM: Example of Flow from not-RPL-aware-leaf to RPL-
	aware-leaf . . . . . . . . . . . . . . . . . . . . . 26		aware-leaf . . . . . . . . . . . . . . . . . . . . . 27
	6.3.4. SM: Example of Flow from not-RPL-aware-leaf to not-		6.3.4. SM: Example of Flow from not-RPL-aware-leaf to not-
	RPL-aware-leaf . . . . . . . . . . . . . . . . . . . 28		RPL-aware-leaf . . . . . . . . . . . . . . . . . . . 29
	7. Non Storing mode . . . . . . . . . . . . . . . . . . . . . . 29		7. Non Storing mode . . . . . . . . . . . . . . . . . . . . . . 30
	7.1. Non-Storing Mode: Interaction between Leaf and Root . . . 30		7.1. Non-Storing Mode: Interaction between Leaf and Root . . . 31
	7.1.1. Non-SM: Example of Flow from RPL-aware-leaf to root . 31		7.1.1. Non-SM: Example of Flow from RPL-aware-leaf to root . 32
	7.1.2. Non-SM: Example of Flow from root to RPL-aware-leaf . 31		7.1.2. Non-SM: Example of Flow from root to RPL-aware-leaf . 32
	7.1.3. Non-SM: Example of Flow from root to not-RPL-aware-		7.1.3. Non-SM: Example of Flow from root to not-RPL-aware-
	leaf . . . . . . . . . . . . . . . . . . . . . . . . 32		leaf . . . . . . . . . . . . . . . . . . . . . . . . 33
	7.1.4. Non-SM: Example of Flow from not-RPL-aware-leaf to		7.1.4. Non-SM: Example of Flow from not-RPL-aware-leaf to
	root . . . . . . . . . . . . . . . . . . . . . . . . 33		root . . . . . . . . . . . . . . . . . . . . . . . . 34
	7.2. Non-Storing Mode: Interaction between Leaf and Internet . 34		7.2. Non-Storing Mode: Interaction between Leaf and Internet . 35
	7.2.1. Non-SM: Example of Flow from RPL-aware-leaf to		7.2.1. Non-SM: Example of Flow from RPL-aware-leaf to
	Internet . . . . . . . . . . . . . . . . . . . . . . 34		Internet . . . . . . . . . . . . . . . . . . . . . . 35
	7.2.2. Non-SM: Example of Flow from Internet to RPL-aware-		7.2.2. Non-SM: Example of Flow from Internet to RPL-aware-
	leaf . . . . . . . . . . . . . . . . . . . . . . . . 35		leaf . . . . . . . . . . . . . . . . . . . . . . . . 36
	7.2.3. Non-SM: Example of Flow from not-RPL-aware-leaf to		7.2.3. Non-SM: Example of Flow from not-RPL-aware-leaf to
	Internet . . . . . . . . . . . . . . . . . . . . . . 36		Internet . . . . . . . . . . . . . . . . . . . . . . 37
	7.2.4. Non-SM: Example of Flow from Internet to not-RPL-		7.2.4. Non-SM: Example of Flow from Internet to not-RPL-
	aware-leaf . . . . . . . . . . . . . . . . . . . . . 37
	7.3. Non-Storing Mode: Interaction between Leafs . . . . . . . 38
	7.3.1. Non-SM: Example of Flow from RPL-aware-leaf to RPL-
	aware-leaf . . . . . . . . . . . . . . . . . . . . . 38		aware-leaf . . . . . . . . . . . . . . . . . . . . . 38
			7.3. Non-Storing Mode: Interaction between Leafs . . . . . . . 39
			7.3.1. Non-SM: Example of Flow from RPL-aware-leaf to RPL-
			aware-leaf . . . . . . . . . . . . . . . . . . . . . 39
	7.3.2. Non-SM: Example of Flow from RPL-aware-leaf to not-		7.3.2. Non-SM: Example of Flow from RPL-aware-leaf to not-
	RPL-aware-leaf . . . . . . . . . . . . . . . . . . . 40
	7.3.3. Non-SM: Example of Flow from not-RPL-aware-leaf to
	RPL-aware-leaf . . . . . . . . . . . . . . . . . . . 41		RPL-aware-leaf . . . . . . . . . . . . . . . . . . . 41
			7.3.3. Non-SM: Example of Flow from not-RPL-aware-leaf to
			RPL-aware-leaf . . . . . . . . . . . . . . . . . . . 42
	7.3.4. Non-SM: Example of Flow from not-RPL-aware-leaf to		7.3.4. Non-SM: Example of Flow from not-RPL-aware-leaf to
	not-RPL-aware-leaf . . . . . . . . . . . . . . . . . 42		not-RPL-aware-leaf . . . . . . . . . . . . . . . . . 43
	8. Operational Considerations of supporting		8. Operational Considerations of supporting
	not-RPL-aware-leaves . . . . . . . . . . . . . . . . . . . . 42		not-RPL-aware-leaves . . . . . . . . . . . . . . . . . . . . 44
	9. Operational considerations of introducing 0x23 . . . . . . . 43		9. Operational considerations of introducing 0x23 . . . . . . . 45
	10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 44		10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 46
	11. Security Considerations . . . . . . . . . . . . . . . . . . . 45		11. Security Considerations . . . . . . . . . . . . . . . . . . . 47
	12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 48		12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 50
	13. References . . . . . . . . . . . . . . . . . . . . . . . . . 48		13. References . . . . . . . . . . . . . . . . . . . . . . . . . 50
	13.1. Normative References . . . . . . . . . . . . . . . . . . 48		13.1. Normative References . . . . . . . . . . . . . . . . . . 50
	13.2. Informative References . . . . . . . . . . . . . . . . . 49		13.2. Informative References . . . . . . . . . . . . . . . . . 51
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 51		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. RFC 6553		[RFC6550] is a routing protocol for constrained networks. RFC 6553
	[RFC6553] defines the "RPL option" (RPI), carried within the IPv6		[RFC6553] defines the "RPL option" (RPI), carried within the IPv6
	Hop-by-Hop header to quickly identify inconsistencies (loops) in the		Hop-by-Hop header to quickly identify inconsistencies (loops) in the
	routing topology. RFC 6554 [RFC6554] defines the "RPL Source Route		routing topology. RFC 6554 [RFC6554] defines the "RPL Source Route
	Header" (RH3), an IPv6 Extension Header to deliver datagrams within a		Header" (RH3), an IPv6 Extension Header to deliver datagrams within a
	RPL routing domain, particularly in non-storing mode.		RPL routing domain, particularly in non-storing mode.
	These various items are referred to as RPL artifacts, and they are		These various items are referred to as RPL artifacts, and they are
	seen on all of the data-plane traffic that occurs in RPL routed		seen on all of the data-plane traffic that occurs in RPL routed
	networks; they do not in general appear on the RPL control plane		networks; they do not in general appear on the RPL control plane
	traffic at all which is mostly hop-by-hop traffic (one exception		traffic at all which is mostly hop-by-hop traffic (one exception
	being DAO messages in non-storing mode).		being DAO messages in non-storing mode).
	It has become clear from attempts to do multi-vendor		It has become clear from attempts to do multi-vendor
	interoperability, and from a desire to compress as many of the above		interoperability, and from a desire to compress as many of the above
	artifacts as possible that not all implementors agree when artifacts		artifacts as possible that not all implementers agree when artifacts
	are necessary, or when they can be safely omitted, or removed.		are necessary, or when they can be safely omitted, or removed.
	An interim meeting went through the 24 cases defined here to discover		The ROLL WG analysized how [RFC2460] rules apply to storing and non-
	if there were any shortcuts, and this document is the result of that		storing use of RPL. The result was 24 data plane use cases. They
	discussion. This document clarifies examples that intend to		are exhaustively outlined here in order to be completely unambiguous.
	illustrate the result of the normative language in RFC8200 and		During the processing of this document, new rules were published as
	RFC6553. In other words, the examples are intended to be normative		[RFC8200], and this document was updated to reflect the normative
	explanation of the results of executing that language.		changes in that document.
			This document updates RFC6553, changing the RPI option value to make
			RFC8200 routers ignore this option by default.
	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 [RFC6554], as well as an efficient IPv6-in-IPv6 technique.		type 3 (RH3) [RFC6554], as well as an efficient IPv6-in-IPv6
			technique.
			Since some of the uses cases here described, use IPv6-in-IPv6
			encapsulation. It MUST take in consideration, when encapsulation is
			applied, the RFC6040 [RFC6040], which defines how the explicit
			congestion notification (ECN) field of the IP header should be
			constructed on entry to and exit from any IPV6-in-IPV6 tunnel.
			Additionally, it is recommended the reading of
			[I-D.ietf-intarea-tunnels].
	1.1. Overview		1.1. Overview
	The rest of the document is organized as follows: Section 2 describes		The rest of the document is organized as follows: Section 2 describes
	the used terminology. Section 3 describes the updates to RFC6553,		the used terminology. Section 3 describes the updates to RFC6553,
	RFC6550 and RFC 8138. Section 4 provides the reference topology used		RFC6550 and RFC 8138. Section 4 provides the reference topology used
	for the uses cases. Section 5 describes the uses cases included.		for the uses cases. Section 5 describes the uses cases included.
	Section 6 describes the storing mode cases and section 7 the non-		Section 6 describes the storing mode cases and section 7 the non-
	storing mode cases. Section 8 describes the operational		storing mode cases. Section 8 describes the operational
	considerations of supporting not-RPL-aware-leaves. Section 9 depicts		considerations of supporting not-RPL-aware-leaves. Section 9 depicts
	skipping to change at page 5, line 18 ¶		skipping to change at page 5, line 32 ¶
	RPL-not-capable: A device which does not implement RPL, thus the		RPL-not-capable: A device which does not implement RPL, thus the
	device is not-RPL-aware. Please note that the device can be found		device is not-RPL-aware. Please note that the device can be found
	inside the LLN. In this document a not-RPL-aware node which is a		inside the LLN. In this document a not-RPL-aware node which is a
	leaf of a DODAG is called not-RPL-aware-leaf (~Raf).		leaf of a DODAG is called not-RPL-aware-leaf (~Raf).
	6LN: [RFC6775] defines it as: "A 6LoWPAN node is any host or router		6LN: [RFC6775] defines it as: "A 6LoWPAN node is any host or router
	participating in a LoWPAN. This term is used when referring to		participating in a LoWPAN. This term is used when referring to
	situations in which either a host or router can play the role		situations in which either a host or router can play the role
	described.". In this document, a 6LN acts as a leaf.		described.". In this document, a 6LN acts as a leaf.
	6LR, 6LBR are defined in [RFC6775].		6LR: [RFC6775] defines it as:" An intermediate router in the LoWPAN
			that is able to send and receive Router Advertisements (RAs) and
			Router Solicitations (RSs) as well as forward and route IPv6 packets.
			6LoWPAN routers are present only in route-over topologies."
			6LBR: [RFC6775] defines it as:"A border router located at the
			junction of separate 6LoWPAN networks or between a 6LoWPAN network
			and another IP network. There may be one or more 6LBRs at the
			6LoWPAN network boundary. A 6LBR is the responsible authority for
			IPv6 prefix propagation for the 6LoWPAN network it is serving. An
			isolated LoWPAN also contains a 6LBR in the network, which provides
			the prefix(es) for the isolated network."
	Flag Day: A transition that involves having a network with different		Flag Day: A transition that involves having a network with different
	values of RPL Option Type. Thus the network does not work correctly.		values of RPL Option Type. Thus the network does not work correctly.
	Hop-by-hop IPv6-in-IPv6 headers: The term "hop-by-hop IPv6-in-IPv6"		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.
	3. Updates to RFC6553, RFC6550 and RFC 8138		RPL defines the RPL Control messages (control plane), a new ICMPv6
			[RFC4443] message with Type 155. DIS (DODAG Information
			Solicitation), DIO (DODAG Information Object) and DAO (Destination
			Advertisement Object) messages are all RPL Control messages but with
			different Code values. A RPL Stack is shown in Figure 1.
	3.1. Updates to RFC 6553		+--------------+
			| Upper Layers |
			| |
			+--------------+
			| RPL |
			| |
			+--------------+
			| ICMPv6 |
			| |
			+--------------+
			| IPv6 |
			| |
			+--------------+
			| 6LoWPAN |
			| |
			+--------------+
			| PHY-MAC |
			| |
			+--------------+
			Figure 1: RPL Stack.
			RPL supports two modes of Downward traffic: in storing mode (RPL-SM),
			it is fully stateful; in non-storing mode (RPL-NSM), it is fully
			source 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 nodes is not supported with the current specifications at the
			time of writing this document.
			3. Updates to RFC6553, RFC6550 and RFC8138
			3.1. Updates to RFC6553: Indicating the new RPI value.
	This modification is required to be able to send, for example, IPv6		This modification is required to be able to send, for example, IPv6
	packets from a RPL-aware-leaf to a not-RPL-aware node through		packets from a RPL-aware-leaf to a not-RPL-aware node through
	Internet (see Section 6.2.1), without requiring IPv6-in-IPv6		Internet (see Section 6.2.1), without requiring IPv6-in-IPv6
	encapsulation.		encapsulation.
	[RFC6553] states as shown below, that in the Option Type field of the		[RFC6553] (Section 6, Page 7) states as shown in Figure 2, that in
	RPL Option header, the two high order bits must be set to '01' and		the Option Type field of the RPL Option header, the two high order
	the third bit is equal to '1'. The first two bits indicate that the		bits must be set to '01' and the third bit is equal to '1'. The
	IPv6 node must discard the packet if it doesn't recognize the option		first two bits indicate that the IPv6 node must discard the packet if
	type, and the third bit indicates that the Option Data may change in		it doesn't recognize the option type, and the third bit indicates
	route. The remaining bits serve as the option type.		that the Option Data may change in route. The remaining bits serve
			as the option type.
	Hex Value Binary Value		Hex Value Binary Value
	act chg rest Description Reference		act chg rest Description Reference
	--------- --- --- ------- ----------------- ----------		--------- --- --- ------- ----------------- ----------
	0x63 01 1 00011 RPL Option [RFC6553]		0x63 01 1 00011 RPL Option [RFC6553]
	Figure 1: Option Type in RPL Option.		Figure 2: Option Type in RPL Option.
	Recent changes in [RFC8200] (section 4, page 8), states: "it is now		This document illustrates that is is not always possible to know for
	expected that nodes along a packet's delivery path only examine and		sure at the source that a packet will only travel within the RPL
	process the Hop-by-Hop Options header if explicitly configured to do		domain or may leave it.
	so". Processing of the Hop-by-Hop Options header (by IPv6
	intermediate nodes) is now optional, but if they are configured to
	process the header, and if such nodes encounter an option with the
	first two bits set to 01, they will drop the packet (if they conform
	to [RFC8200]). Host systems should do the same, irrespective of the
	configuration.
	Based on that, if an IPv6 (intermediate) node (RPL-not-capable)		At the time [RFC6553] was published, leaking a Hop-by-Hop header in
	receives a packet with an RPL Option, it should ignore the HBH RPL		the outer IPv6 header chain could potentially impact core routers in
	option (skip over this option and continue processing the header).		the internet. So at that time, it was decided to encapsulate any
	This is relevant, as it was mentioned previously, in the case that		packet with a RPL option using IPv6-in-IPv6 in all cases where it was
	there is a flow from RPL-aware-leaf to Internet (see Section 6.2.1).		unclear whether the packet would remain within the RPL domain. In
			the exception case where a packet would still leak, the Option Type
			would ensure that the first router in the Internet that does not
			recognize the option would drop the packet and protect the rest of
			the network.
	Thus, this document updates the Option Type field to: the two high		Even with [RFC8138] that compresses the IP-in-IP header, this
	order bits MUST be set to '00' and the third bit is equal to '1'.		approach yields extra bytes in a packet which means consuming more
	The first two bits indicate that the IPv6 node MUST skip over this		energy, more bandwidth, incurring higher chances of loss and possibly
	option and continue processing the header ([RFC8200] Section 4.2) if		causing a fragmentation at the 6LoWPAN level. This impacts the daily
	it doesn't recognize the option type, and the third bit continues to		operation of constrained devices for a case that generally does not
	be set to indicate that the Option Data may change en route. The		happen and would not heavily impact the core anyway.
	remaining bits serve as the option type and remain as 0x3. This
	ensures that a packet that leaves the RPL domain of an LLN (or that
	leaves the LLN entirely) will not be discarded when it contains the
	[RFC6553] RPL Hop-by-Hop option known as RPI.
	This is a significant update to [RFC6553]. [RFCXXXX] represents this		While intention was and remains that the Hop-by-Hop header with a RPL
	document.		option should be confined within the RPL domain, this specification
			modifies this behavior in order to reduce the dependency on IP-in-IP
			and protect the constrained devices. Section 4 of [RFC8200]
			clarifies the behaviour of routers in the Internet as follows: "it is
			now expected that nodes along a packet's delivery path only examine
			and process the Hop-by-Hop Options header if explicitly configured to
			do so". This means that while it should be avoided, the impact on
			the Internet of leaking a Hop-by-Hop header is acceptable.
			When unclear about the travel of a packet, it becomes preferable for
			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,
			the packet should reach its destination and should not be discarded
			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
			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
			to [RFC8200], it will drop the packet. Host systems should do the
			same, irrespective of the configuration.
			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
			'1'. The first two bits indicate that the IPv6 node MUST skip over
			this option and continue processing the header ([RFC8200]
			Section 4.2) if it doesn't recognize the option type, and the third
			bit continues to be set to indicate that the Option Data may change
			en route. The remaining bits serve as the option type and remain as
			0x3. This ensures that a packet that leaves the RPL domain of an LLN
			(or that leaves the LLN entirely) will not be discarded when it
			contains the [RFC6553] RPL Hop-by-Hop option known as RPI.
			With the new Option Type, if an IPv6 (intermediate) node (RPL-not-
			capable) receives a packet with an RPL Option, it should ignore the
			Hop-by-Hop RPL option (skip over this option and continue processing
			the header). This is relevant, as it was mentioned previously, in
			the case that there is a flow from RPL-aware-leaf to Internet (see
			Section 6.2.1).
			This is a significant update to [RFC6553].
	Hex Value Binary Value		Hex Value Binary Value
	act chg rest Description Reference		act chg rest Description Reference
	--------- --- --- ------- ----------------- ----------		--------- --- --- ------- ----------------- ----------
	0x23 00 1 00011 RPL Option [RFCXXXX]		0x23 00 1 00011 RPL Option [RFCXXXX]
	Figure 2: Revised Option Type in RPL Option.		Figure 3: Revised Option Type in RPL Option.
	This change creates a flag day for existing networks which are		Without the signaling described below, this change would otherwise
	currently using 0x63 as the RPI value. A move to 0x23 will not be		create a flag day for existing networks which are currently using
	understood by those networks. It is suggested that implementations		0x63 as the RPI value. A move to 0x23 will not be understood by
	accept both 0x63 and 0x23 when processing.		those networks. It is suggested that implementations accept both
			0x63 and 0x23 when processing.
	In the cases where a forwarding node is forwarding traffic that is		When forwarding packets, implementations SHOULD use the same value as
	not addressed directly to it (such as when the outer IPv6-in-IPv6		it was received (This is required because, RPI type code can not be
	header is not a Link-Local address), then RFC8200 forbids changing		changed by [RFC8200]). It allows to the network to be incrementally
	the RPI type code when forwarding.		upgraded, and for the DODAG root to know which parts of the network
			are upgraded.
	When forwarding traffic that is wrapped in Link-Local IPv6-in-IPv6		When originating new packets, implementations SHOULD have an option
	headers, the forwarding node is in effect originating new packets,		to determine which value to originate with, this option is controlled
	and it MAY make a choice as to whether to use the old (0x63) RPI Type		by the DIO option described below.
	code, or the new (0x23) RPI Type code. In that situation,
	implementations SHOULD use the same value as was received. This
	allows to the network to be incrementally upgraded, and in some cases
	may allow the DODAG root to know which parts of the network are
	upgraded.
	A network which is switching from straight 6lowpan compression		A network which is switching from straight 6lowpan compression
	mechanism to those described in [RFC8138] will experience a flag day		mechanism to those described in [RFC8138] will experience a flag day
	in the data compression anyway, and if possible this change can be		in the data compression anyway, and if possible this change can be
	deployed at the same time.		deployed at the same time.
	The change of RPI option type from 0x63 to 0x23, makes all [RFC8200]		The change of RPI option type from 0x63 to 0x23, makes all [RFC8200]
	Section 4.2 compliant nodes tolerant of the RPL artifacts. There is		Section 4.2 compliant nodes tolerant of the RPL artifacts. There is
	therefore no longer a necessity to remove the artifacts when sending		therefore no longer a necessity to remove the artifacts when sending
	traffic to the Internet. This change clarifies when to use an IPv6-		traffic to the Internet. This change clarifies when to use an IPv6-
	in-IPv6 header, and how to address them: The Hop-by-Hop Options		in-IPv6 header, and how to address them: The Hop-by-Hop Options
	Header containing the RPI option SHOULD always be added when 6LRs		Header containing the RPI option MUST always be added when 6LRs
	originate packets (without IPv6-in-IPv6 headers), and IPv6-in-IPv6		originate packets (without IPv6-in-IPv6 headers), and IPv6-in-IPv6
	headers SHOULD always be added when a 6LR find that it needs to		headers MUST always be added when a 6LR find that it needs to insert
	insert a Hop-by-Hop Options Header containing the RPI option. The		a Hop-by-Hop Options Header containing the RPI option. The IPv6-in-
	IPv6-in-IPv6 header is to be addressed to the RPL root when on the		IPv6 header is to be addressed to the RPL root when on the way up,
	way up, and to the end-host when on the way down.		and to the end-host when on the way down.
	Non-constrained uses of RPL are not in scope of this document, and		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. [I-D.ietf-anima-autonomic-control-plane].
	In the non-storing case, dealing with non-RPL aware leaf nodes is		In the non-storing case, dealing with not-RPL aware leaf nodes is
	much easier as the 6LBR (DODAG root) has complete knowledge about the		much easier as the 6LBR (DODAG root) has complete knowledge about the
	connectivity of all DODAG nodes, and all traffic flows through the		connectivity of all DODAG nodes, and all traffic flows through the
	root node.		root node.
	The 6LBR can recognize non-RPL aware leaf nodes because it will		The 6LBR can recognize not-RPL aware leaf nodes because it will
	receive a DAO about that node from the 6LR immediately above that		receive a DAO about that node from the 6LR immediately above that
	non-RPL aware node. This means that the non-storing mode case can		not-RPL aware node. This means that the non-storing mode case can
	avoid ever using hop-by-hop IPv6-in-IPv6 headers for traffic		avoid ever using hop-by-hop IPv6-in-IPv6 headers for traffic
	originating from the root to leafs.		originating from the root to leafs.
	The non-storing mode case does not require the type change from 0x63		The non-storing mode case does not require the type change from 0x63
	to 0x23, as the root can always create the right packet. The type		to 0x23, as the root can always create the right packet. The type
	change does not adversely affect the non-storing case.		change does not adversely affect the non-storing case.
	3.2. Updates to RFC 8138		3.2. Updates to RFC6550: Indicating the new RPI in the DODAG
	RPI-6LoRH header provides a compressed form for the RPL RPI [RFC8138]
	in section 6. A node that is decompressing this header MUST
	decompress using the RPL RPI option type that is currently active:
	that is, a choice between 0x23 (new) and 0x63 (old). The node will
	know which to use based upon the presence of the DODAG Configuration
	Option described in the next section. E.g. If the network is in
	0x23 mode (by DIO option), then it should be decompressed to 0x23.
	[RFC8138] section 7 documents how to compress the IPv6-in-IPv6
	header.
	There are potential significant advantages to having a single code
	path that always processes IPv6-in-IPv6 headers with no options.
	In Storing Mode, for the examples of Flow from RPL-aware-leaf to non-
	RPL-aware-leaf and non-RPL-aware-leaf to non-RPL-aware-leaf 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 compressed
	with [RFC8138] section 7.
	+--+-----+---+--------------+-----------+-----------+-----------+
	|1 | 0|0 |TSE| 6LoRH Type 6 | Hop Limit | RPI-6LoRH |LOWPAN IPHC|
	+--+-----+---+--------------+-----------+-----------+-----------+
	Figure 3: IPv6-in-IPv6 (RPI).
	3.3. Updates to RFC 6550: 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. Without this, there could be a mix of new nodes		can be safely used. This means, the flag is going to indicate the
	(which understand 0x23 and 0x63), and old nodes (which understand		type of RPI that the network is using. Thus, when a node join to a
	0x63 only). A new node would not know if it was safe to use 0x23.		network will know which value to use. With this, RPL-capable nodes
			know if it is safe to use 0x23 when creating a new RPI. A node that
			forwards a packet with an RPI MUST not modify the option type of the
			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
	DIO messages. The DODAG Configuration option distributes		DIO messages. The DODAG Configuration option distributes
	configuration information. It is generally static, and does not		configuration information. It is generally static, and does not
	change within the DODAG. This information is configured at the DODAG		change within the DODAG. This information is configured at the DODAG
	root and distributed throughout the DODAG with the DODAG		root and distributed throughout the DODAG with the DODAG
	Configuration option. Nodes other than the DODAG root do not modify		Configuration option. Nodes other than the DODAG root do not modify
	this information when propagating the DODAG Configuration option.		this information when propagating the DODAG Configuration option.
	The DODAG Configuration Option has a Flag field which is modified by		The DODAG Configuration Option has a Flag field which is modified by
	this document. Currently, the DODAG Configuration Option in		this document. Currently, the DODAG Configuration Option in
	[RFC6550] states: "the unused bits MUST be initialize to zero by the		[RFC6550] states: "the unused bits MUST be initialize to zero by the
	sender and MUST be ignored by the receiver".		sender and MUST be ignored by the receiver".
	Bit number three of the flag field in the DODAG Configuration option		Bit number three of the flag field in the DODAG Configuration option
	is to be used as follows:		is to be used as shown in Figure 4 :
	+------------+-----------------+---------------+		+------------+-----------------+---------------+
	| Bit number | Description | Reference |		| Bit number | Description | Reference |
	+------------+-----------------+---------------+		+------------+-----------------+---------------+
	| 3 | RPI 0x23 enable | This document |		| 3 | RPI 0x23 enable | This document |
	+------------+-----------------+---------------+		+------------+-----------------+---------------+
	Figure 4: DODAG Configuration Option Flag to indicate the RPI-flag-		Figure 4: DODAG Configuration Option Flag to indicate the RPI-flag-
	day.		day.
	In case of rebooting, the node (6LN or 6LR) does not remember if the		In case of rebooting, the node (6LN or 6LR) does not remember if the
	flag is set, so DIO messages would be set with the flag unset until a		flag is set, so DIO messages would be set with the flag unset until a
	DIO is received with the flag set.		DIO is received with the flag set.
			3.3. Updates to RFC8138: Indicating the way to decompress with the new
			RPI value.
			This modification is required to be able to decompress the RPL RPI
			option with the new value (0x23).
			RPI-6LoRH header provides a compressed form for the RPL RPI [RFC8138]
			in section 6. A node that is decompressing this header MUST
			decompress using the RPL RPI option type that is currently active:
			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
			Configuration Option defined in Section 3.2. E.g. If the network is
			in 0x23 mode (by DIO option), then it should be decompressed to 0x23.
			[RFC8138] section 7 documents how to compress the IPv6-in-IPv6
			header.
			There are potential significant advantages to having a single code
			path that always processes IPv6-in-IPv6 headers with no conditional
			branches.
			In Storing Mode, for the examples of Flow from RPL-aware-leaf to not-
			RPL-aware-leaf and not-RPL-aware-leaf to not-RPL-aware-leaf 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 compressed
			with [RFC8138] section 7. As exemplification of compressing the RPI,
			section A.1 of [RFC8138] illustrates the case in Storing mode where
			the packet is received from the Internet, then the root encapsulates
			the packet to insert the RPI. The result is shown in Figure 5.
			+-+ ... -+-+-...-+-+-- ... -+-+-+-+- ... -+-+ ... -+-+-+ ... -+-+-+...
			|11110001| RPI- | IP-in-IP | NH=1 |11110CPP| Compressed | UDP
			|Page 1 | 6LoRH | 6LoRH | LOWPAN_IPHC | UDP | UDP header | Payld
			+-+ ... -+-+-...-+-+-- ... -+-+-+-+- ... -+-+ ... -+-+-+ ... -+-+-+...
			Figure 5: RPI Inserted by the Root in Storing Mode
	4. Sample/reference topology		4. Sample/reference topology
	A RPL network in general is composed of a 6LBR (6LoWPAN Border		A RPL network in general is composed of a 6LBR (6LoWPAN Border
	Router), Backbone Router (6BBR), 6LR (6LoWPAN Router) and 6LN		Router), Backbone Router (6BBR), 6LR (6LoWPAN Router) and 6LN
	(6LoWPAN Node) as leaf logically organized in a DODAG structure.		(6LoWPAN Node) as leaf logically organized in a DODAG structure.
	Figure 4 shows the reference RPL Topology for this document. The		Figure 6 shows the reference RPL Topology for this document. The
	letters above the nodes are there so that they may be referenced in		letters above the nodes are there so that they may be referenced in
	subsequent sections. In the figure, 6LR represents a full router		subsequent sections. In the figure, 6LR represents a full router
	node. The 6LN is a RPL aware router, or host (as a leaf).		node. The 6LN is a RPL aware router, or host (as a leaf).
	Additionally, for simplification purposes, it is supposed that the		Additionally, for simplification purposes, it is supposed that the
	6LBR has direct access to Internet, thus the 6BBR is not present in		6LBR has direct access to Internet, thus the 6BBR is not present in
	the figure.		the figure.
	The 6LN leaves (Raf - "RPL aware leaf"-) marked as (F, H and I) are		The 6LN leaves (Raf) marked as (F, H and I) are RPL nodes with no
	RPL nodes with no children hosts.		children hosts.
	The leafs marked as ~Raf "not-RPL aware leaf" (G and J) are devices		The leafs marked as ~Raf (G and J) are devices which do not speak RPL
	which do not speak RPL at all (not-RPL-aware), but uses Router-		at all (not-RPL-aware), but uses Router-Advertisements, 6LowPAN DAR/
	Advertisements, 6LowPAN DAR/DAC and efficient-ND only to participate		DAC and efficient-ND only to participate in the network [RFC6775].
	in the network [RFC6775]. In the document these leafs (G and J) are		In the document these leafs (G and J) are also referred to as an IPv6
	also referred to as an IPv6 node.		node.
	The 6LBR ("A") in the figure is the root of the Global DODAG.		The 6LBR ("A") in the figure is the root of the Global DODAG.
	+------------+		+------------+
	| INTERNET ----------+		| INTERNET ----------+
	| | |		| | |
	+------------+ |		+------------+ |
	|		|
	|		|
	|		|
	skipping to change at page 11, line 24 ¶		skipping to change at page 13, line 24 ¶
	|6LBR |		|6LBR |
	+-----------|(root) |-------+		+-----------|(root) |-------+
	| +-------+ |		| +-------+ |
	| |		| |
	| |		| |
	| |		| |
	| |		| |
	| B |C		| B |C
	+---|---+ +---|---+		+---|---+ +---|---+
	| 6LR | | 6LR |		| 6LR | | 6LR |
	+-------->| |--+ +--- ---+		+---------| |--+ +--- ---+
	| +-------+ | | +-------+ |		| +-------+ | | +-------+ |
	| | | |		| | | |
	| | | |		| | | |
	| | | |		| | | |
	| | | |		| | | |
	| D | E | |		| D | E | |
	+-|-----+ +---|---+ | |		+-|-----+ +---|---+ | |
	| 6LR | | 6LR | | |		| 6LR | | 6LR | | |
	| | +------ | | |		| | +------ | | |
	+---|---+ | +---|---+ | |		+---|---+ | +---|---+ | |
	skipping to change at page 11, line 46 ¶		skipping to change at page 13, line 46 ¶
	| | +--+ | |		| | +--+ | |
	| | | | |		| | | | |
	| | | | |		| | | | |
	| | | I | J |		| | | I | J |
	F | | G | H | |		F | | G | H | |
	+-----+-+ +-|-----+ +---|--+ +---|---+ +---|---+		+-----+-+ +-|-----+ +---|--+ +---|---+ +---|---+
	| Raf | | ~Raf | | Raf | | Raf | | ~Raf |		| Raf | | ~Raf | | Raf | | Raf | | ~Raf |
	| 6LN | | 6LN | | 6LN | | 6LN | | 6LN |		| 6LN | | 6LN | | 6LN | | 6LN | | 6LN |
	+-------+ +-------+ +------+ +-------+ +-------+		+-------+ +-------+ +------+ +-------+ +-------+
	Figure 5: A reference RPL Topology.		Figure 6: A reference RPL Topology.
	RPL defines the RPL Control messages (control plane), a new ICMPv6
	[RFC4443] message with Type 155. DIS (DODAG Information
	Solicitation), DIO (DODAG Information Object) and DAO (Destination
	Advertisement Object) messages are all RPL Control messages but with
	different Code values. A RPL Stack is shown in Figure 5.
	+--------------+
	| Upper Layers |
	| |
	+--------------+
	| RPL |
	| |
	+--------------+
	| ICMPv6 |
	| |
	+--------------+
	| IPv6 |
	| |
	+--------------+
	| 6LoWPAN |
	| |
	+--------------+
	| PHY-MAC |
	| |
	+--------------+
	Figure 6: RPL Stack.
	RPL supports two modes of Downward traffic: in storing mode (RPL-SM),
	it is fully stateful; in non-storing (RPL-NSM), it is fully source
	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
	nodes is not supported with the current specifications at the time of
	writing this document.
	5. Use cases		5. Use cases
	In the data plane a combination of RFC6553, RFC6554 and IPv6-in-IPv6		In the data plane a combination of RFC6553, RFC6554 and IPv6-in-IPv6
	encapsulation are going to be analyzed for a number of representative		encapsulation are going to be analyzed for a number of representative
	traffic flows.		traffic flows.
	This document assumes that the LLN is using the no-drop RPI option		This document assumes that the LLN is using the no-drop RPI option
	(0x23).		(0x23).
	The uses cases describe the communication between RPL-aware-nodes,		The uses cases describe the communication between RPL-aware-nodes,
	with the root (6LBR), and with Internet. This document also describe		with the root (6LBR), and with Internet. This document also
	the communication between nodes acting as leaves that do not		describes the communication between nodes acting as leaves that do
	understand RPL, but are part of the LLN. these nodes are named as		not understand RPL (~Raf nodes), but are part of the LLN. (e.g.
	not-RPL-aware-leaf, mentioned previously. (e.g. Section 6.1.4 Flow		Section 6.1.4 Flow from not-RPL-aware-leaf to root) This document
	from not-RPL-aware-leaf to root) This document describes also how is		depicts as well the communication inside of the LLN when it has the
	the communication inside of the LLN when it has the final destination		final destination addressed outside of the LLN e.g. with destination
	addressed outside of the LLN e.g. with destination to Internet.		to Internet. For example, Section 6.2.3 Flow from not-RPL-aware-leaf
	(e.g. Section 6.2.3 Flow from not-RPL-aware-leaf to Internet)		to Internet
	The uses cases comprise as follow:		The uses cases comprise as follow:
	Interaction between Leaf and Root:		Interaction between Leaf and Root:
	RPL-aware-leaf to root		RPL-aware-leaf(Raf) to root
	root to RPL-aware-leaf		root to RPL-aware-leaf(Raf)
	not-RPL-aware-leaf to root		not-RPL-aware-leaf(~Raf) to root
	root to not-RPL-aware-leaf		root to not-RPL-aware-leaf(~Raf)
	Interaction between Leaf and Internet:		Interaction between Leaf and Internet:
	RPL-aware-leaf to Internet		RPL-aware-leaf(Raf) to Internet
	Internet to RPL-aware-leaf		Internet to RPL-aware-leaf(Raf)
	not-RPL-aware-leaf to Internet		not-RPL-aware-leaf(~Raf) to Internet
	Internet to not-RPL-aware-leaf		Internet to not-RPL-aware-leaf(~Raf)
	Interaction between Leafs:		Interaction between Leafs:
	RPL-aware-leaf to RPL-aware-leaf (storing and non-storing)		RPL-aware-leaf(Raf) to RPL-aware-leaf(Raf) (storing and non-
			storing)
	RPL-aware-leaf to not-RPL-aware-leaf (non-storing)
	not-RPL-aware-leaf to RPL-aware-leaf (storing and non-storing)		RPL-aware-leaf(Raf) to not-RPL-aware-leaf(~Raf) (non-storing)
			not-RPL-aware-leaf(~Raf) to RPL-aware-leaf(Raf) (storing and non-
			storing)
	not-RPL-aware-leaf to not-RPL-aware-leaf (non-storing)		not-RPL-aware-leaf(~Raf) to not-RPL-aware-leaf(~Raf) (non-storing)
	This document is consistent with the rule that a Header cannot be		This document is consistent with the rule that a Header cannot be
	inserted or removed on the fly inside an IPv6 packet that is being		inserted or removed on the fly inside an IPv6 packet that is being
	routed. This is a fundamental precept of the IPv6 architecture as		routed. This is a fundamental precept of the IPv6 architecture as
	outlined in [RFC8200]. Extensions may not be added or removed except		outlined in [RFC8200]. Extensions headers may not be added or
	by the sender or the receiver.		removed except by the sender or the receiver.
	However, unlike [RFC6553], the Hop-by-Hop Option Header used for the		However, unlike [RFC6553], the Hop-by-Hop Option Header used for the
	RPI artifact has the first two bits set to '00'. This means that the		RPI artifact has the first two bits set to '00'. This means that the
	RPI artifact will be ignored when received by a host or router that		RPI artifact will be ignored when received by a host or router that
	does not understand that option ( Section 4.2 [RFC8200]).		does not understand that option ( Section 4.2 [RFC8200]).
	This means that when the no-drop RPI option code 0x23 is used, a		This means that when the no-drop RPI option code 0x23 is used, a
	packet that leaves the RPL domain of an LLN (or that leaves the LLN		packet that leaves the RPL domain of an LLN (or that leaves the LLN
	entirely) will not be discarded when it contains the [RFC6553] RPL		entirely) will not be discarded when it contains the [RFC6553] RPL
	Hop-by-Hop option known as RPI. Thus, the RPI Hop-by-Hop option is		Hop-by-Hop option known as RPI. Thus, the RPI Hop-by-Hop option is
	left in place even if the end host does not understand it.		left in place even if the end host does not understand it.
	NOTE: There is some possible security risk when the RPI information		NOTE: No clear attack has been described when the RPI information is
	is released to the Internet. At this point this is a theoretical		released to the Internet. At a minimum, it is clear that the RPI
	situation; no clear attack has been described. At worst, it is clear		option would waste some network bandwidth when it escapes. This is
	that the RPI option would waste some network bandwidth when it		traded off against the savings in the LLN by not having to
	escapes. This is traded off against the savings in the LLN by not		encapsulate the packet in order to remove the artifact. Please check
	having to encapsulate the packet in order to remove the artifact.		the Security Considerations sections Section 11 for further details.
	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 SHOULD force it to zero when passing the packet out to the		DODAG root MUST force it to zero when passing the packet out to the
	Internet. The Internet will therefore not see any SenderRank		Internet. The Internet will therefore not see any SenderRank
	information.		information.
	Despite being legal to leave the RPI artifact in place, an		Despite being legal to leave the RPI artifact in place, an
	intermediate router that needs to add an extension header (RH3 or RPI		intermediate router that needs to add an extension header (e.g. RH3
	Option) MUST still encapsulate the packet in an (additional) outer IP		or RPI Option) MUST still encapsulate the packet in an (additional)
	header. The new header is placed after this new outer IP header.		outer IP header. The new header is placed after this new outer IP
			header.
	A corollary is that an RH3 or RPI Option can only be removed by an		A corollary is that an RH3 or RPI Option can only be removed by an
	intermediate router if it is placed in an encapsulating IPv6 Header,		intermediate router if it is placed in an encapsulating IPv6 Header,
	which is addressed TO the intermediate router. When it does so, the		which is addressed TO the intermediate router. When it does so, the
	whole encapsulating header must be removed. (A replacement may be		whole encapsulating header must be removed. (A replacement may be
	added). This sometimes can result in outer IP headers being		added). This sometimes can result in outer IP headers being
	addressed to the next hop router using link-local address.		addressed to the next hop router using link-local address.
	Both RPI and RH3 headers may be modified in very specific ways by		Both RPI and RH3 headers may be modified in very specific ways by
	routers on the path of the packet without the need to add to remove		routers on the path of the packet without the need to add and remove
	an encapsulating header. Both headers were designed with this		an encapsulating header. Both headers were designed with this
	modification in mind, and both the RPL RH3 and the RPL option are		modification in mind, and both the RPL RH3 and the RPL option are
	marked mutable but recoverable: so an IPsec AH security header can be		marked mutable but recoverable: so an IPsec AH security header can be
	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. There is one		RPI MUST be present in every single RPL data packet.
	exception in non-storing mode: when a packet is going down from the
	root the RPI MAY be omitted. The rational is that in a downward non-
	storing mode, the entire route is written, so there can be no loops
	by construction, nor any confusion about which forwarding table to
	use (as the root has already made all routing decisions). However,
	there are still cases, such as in 6tisch, where the instanceID
	portion of the RPI header may still be needed [RFC8180] to pick an
	appropriate priority or channel at each hop.
	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
	[I-D.ietf-anima-autonomic-control-plane].		[I-D.ietf-anima-autonomic-control-plane].
	The earlier examples are more extensive to make sure that the process		The earlier examples are more extensive to make sure that the process
	is clear, while later examples are more concise.		is clear, while later examples are more concise.
	6. Storing mode		6. Storing mode
	In storing mode (fully stateful), the sender can determine if the		In storing mode (fully stateful), the sender can determine if the
	destination is inside the LLN by looking if the destination address		destination is inside the LLN by looking if the destination address
	is matched by the DIO's Prefix Information Option (PIO) option.		is matched by the DIO's Prefix Information Option (PIO) option.
	The following table (Figure 7) itemizes which headers are needed in		The following table (Figure 7) itemizes which headers are needed in
	each of the following scenarios. It indicate if an IPv6-in-IPv6		each of the following scenarios. It indicates if the IPv6-in-IPv6
	header must be inserted, and whether the destination address of the		header that is added, must be addressed to the final destination (the
	IPv6-in-IPv6 header is the next hop, or the final target address.		Raf node that is the target(tgt)), to the "root" or if a hop-by-hop
	There are these possible situations: hop-by-hop necessary (indicated		header must be added (indicated by "hop").
	by "hop"), or final target address possible (indicated by "tgt"). In
	all cases hop by hop may be used rather than the final target
	address.
	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".		"No". If the IPv6-in-IPv6 header is needed is a "must".
	In all cases the RPI headers are needed, since it identifies		In all cases the RPI headers are needed, since it identifies
	inconsistencies (loops) in the routing topology. In all cases the		inconsistencies (loops) in the routing topology. In all cases the
	RH3 is not needed because it is not used in storing mode.		RH3 is not needed because it is not used in storing mode.
	In each case, 6LR_i are the intermediate routers from source to		In each case, 6LR_i is the intermediate router 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 go 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 (see		The leaf can be a router 6LR or a host, both indicated as 6LN. The
	Figure 5).		root refers to the 6LBR (see Figure 6).
	+---------------------+--------------+------------+--------------+		+---------------------+--------------+------------+------------------+
	| Interaction between | Use Case |IPv6-in-IPv6| v6-in-v6 dst |		| Interaction between | Use Case |IPv6-in-IPv6| IPv6-in-IPv6 dst |
	+---------------------+--------------+------------+--------------+		+---------------------+--------------+------------+------------------+
	| | Raf to root | No | No |		| | Raf to root | No | No |
	+ +--------------+------------+--------------+		+ +--------------+------------+------------------+
	| Leaf - Root | root to Raf | No | No |		| Leaf - Root | root to Raf | No | No |
	+ +--------------+------------+--------------+		+ +--------------+------------+------------------+
	| | root to ~Raf | No | No |		| | root to ~Raf | No | No |
	+ +--------------+------------+--------------+		+ +--------------+------------+------------------+
	| | ~Raf to root | must | root |		| | ~Raf to root | must | root |
	+---------------------+--------------+------------+--------------+		+---------------------+--------------+------------+------------------+
	| | Raf to Int | No | No |		| | Raf to Int | No | No |
	+ +--------------+------------+--------------+		+ +--------------+------------+------------------+
	| Leaf - Internet | Int to Raf | must | tgt (Raf) |		| Leaf - Internet | Int to Raf | must | Raf (tgt) |
	+ +--------------+------------+--------------+		+ +--------------+------------+------------------+
	| | ~Raf to Int | must | root |		| | ~Raf to Int | must | root |
	+ +--------------+------------+--------------+		+ +--------------+------------+------------------+
	| | Int to ~Raf | must | hop |		| | Int to ~Raf | must | hop |
	+---------------------+--------------+------------+--------------+		+---------------------+--------------+------------+------------------+
	| | Raf to Raf | No | No |		| | Raf to Raf | No | No |
	+ +--------------+------------+--------------+		+ +--------------+------------+------------------+
	| | Raf to ~Raf | No | No |		| | Raf to ~Raf | No | No |
	+ Leaf - Leaf +--------------+------------+--------------+		+ Leaf - Leaf +--------------+------------+------------------+
	| | ~Raf to Raf | must | tgt (Raf) |		| | ~Raf to Raf | must | Raf (tgt) |
	+ +--------------+------------+--------------+		+ +--------------+------------+------------------+
	| | ~Raf to ~Raf | Yes | hop |		| | ~Raf to ~Raf | must | ~Raf |
	+---------------------+--------------+------------+--------------+		+---------------------+--------------+------------+------------------+
	Figure 7: Table of IPv6-in-IPv6 encapsulation in Storing mode.		Figure 7: Table of IPv6-in-IPv6 encapsulation in Storing mode.
	6.1. Storing Mode: Interaction between Leaf and Root		6.1. Storing Mode: Interaction between Leaf and Root
	In this section is described the communication flow in storing mode		In this section is described the communication flow in storing mode
	(SM) between,		(SM) between,
	RPL-aware-leaf to root		RPL-aware-leaf to root
	skipping to change at page 17, line 21 ¶		skipping to change at page 18, line 16 ¶
	generally issue DIO messages; a leaf node accepts DIO messages from		generally issue DIO messages; a leaf node accepts DIO messages from
	upstream. (When the inconsistency in routing occurs, a leaf node		upstream. (When the inconsistency in routing occurs, a leaf node
	will generate a DIO with an infinite rank, to fix it). It may issue		will generate a DIO with an infinite rank, to fix it). It may issue
	DAO and DIS messages though it generally ignores DAO and DIS		DAO and DIS messages though it generally ignores DAO and DIS
	messages.		messages.
	In this case the flow comprises:		In this case the flow comprises:
	RPL-aware-leaf (6LN) --> 6LR_i --> root(6LBR)		RPL-aware-leaf (6LN) --> 6LR_i --> root(6LBR)
	For example, a communication flow could be: Node F --> Node E -->		For example, a communication flow could be: Node F --> Node D -->
	Node B --> Node A root(6LBR)		Node B --> Node A root(6LBR)
	As it was mentioned in this document 6LRs, 6LBR are always full-		As it was mentioned in this document 6LRs, 6LBR are always full-
	fledged RPL routers.		fledged RPL routers.
	The 6LN (Node F) inserts the RPI header, and sends the packet to 6LR		The 6LN (Node F) inserts the RPI header, and sends the packet to 6LR
	(Node E) which decrements the rank in RPI and sends the packet up.		(Node E) which decrements the rank in RPI and sends the packet up.
	When the packet arrives at 6LBR (Node A), the RPI is removed and the		When the packet arrives at 6LBR (Node A), the RPI is removed and the
	packet is processed.		packet is processed.
	No IPv6-in-IPv6 header is required.		No IPv6-in-IPv6 header is required.
	The RPI header can be removed by the 6LBR because the packet is		The RPI header can be removed by the 6LBR because the packet is
	addressed to the 6LBR. The 6LN must know that it is communicating		addressed to the 6LBR. The 6LN must know that it is communicating
	with the 6LBR to make use of this scenario. The 6LN can know the		with the 6LBR to make use of this scenario. The 6LN can know the
	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.
	| Header | 6LN | 6LR_i | 6LBR |
	+-------------------+-----+-------+------+		+-------------------+---------+-------+----------+
	| Inserted headers | RPI | -- | -- |		| Header | 6LN src | 6LR_i | 6LBR dst |
	| Removed headers | -- | -- | RPI |		+-------------------+---------+-------+----------+
	| Re-added headers | -- | -- | -- |		| Inserted headers | RPI | -- | -- |
	| Modified headers | -- | RPI | -- |		| Removed headers | -- | -- | RPI |
	| Untouched headers | -- | -- | -- |		| Re-added headers | -- | -- | -- |
	+-------------------+-----+-------+------+		| Modified headers | -- | RPI | -- |
			| Untouched headers | -- | -- | -- |
			+-------------------+---------+-------+----------+
	Table 1: Storing: Summary of the use of headers from RPL-aware-leaf		Table 1: Storing: Summary of the use of headers from RPL-aware-leaf
	to root		to root
	6.1.2. SM: Example of Flow from root to RPL-aware-leaf		6.1.2. SM: Example of Flow from root to RPL-aware-leaf
	In this case the flow comprises:		In this case the flow comprises:
	root (6LBR) --> 6LR_i --> RPL-aware-leaf (6LN)		root (6LBR) --> 6LR_i --> RPL-aware-leaf (6LN)
	For example, a communication flow could be: Node A root(6LBR) -->		For example, a communication flow could be: Node A root(6LBR) -->
	Node B --> Node D --> Node F		Node B --> Node D --> Node F
	In this case the 6LBR inserts RPI header and sends the packet down,		In this case the 6LBR inserts RPI header and sends the packet down,
	the 6LR is going to increment the rank in RPI (it examines the		the 6LR is going to increment the rank in RPI (it examines the
	instanceID to identify the right forwarding table), the packet is		instanceID to identify the right forwarding table), the packet is
	processed in the 6LN and the RPI removed.		processed in the 6LN and the RPI removed.
	No IPv6-in-IPv6 header is required.		No IPv6-in-IPv6 header is required.
			The Table 2 summarizes what headers are needed for this use case.
	+-------------------+------+-------+------+		+-------------------+------+-------+------+
	| Header | 6LBR | 6LR_i | 6LN |		| Header | 6LBR | 6LR_i | 6LN |
	+-------------------+------+-------+------+		+-------------------+------+-------+------+
	| Inserted headers | RPI | -- | -- |		| Inserted headers | RPI | -- | -- |
	| Removed headers | -- | -- | RPI |		| Removed headers | -- | -- | RPI |
	| Re-added headers | -- | -- | -- |		| Re-added headers | -- | -- | -- |
	| Modified headers | -- | RPI | -- |		| Modified headers | -- | RPI | -- |
	| Untouched headers | -- | -- | -- |		| Untouched headers | -- | -- | -- |
	+-------------------+------+-------+------+		+-------------------+------+-------+------+
	skipping to change at page 19, line 5 ¶		skipping to change at page 19, line 48 ¶
	In this case the flow comprises:		In this case the flow comprises:
	root (6LBR) --> 6LR_i --> not-RPL-aware-leaf (IPv6)		root (6LBR) --> 6LR_i --> not-RPL-aware-leaf (IPv6)
	For example, a communication flow could be: Node A root(6LBR) -->		For example, a communication flow could be: Node A root(6LBR) -->
	Node B --> Node E --> Node G		Node B --> Node E --> Node G
	As the RPI extension can be ignored by the not-RPL-aware leaf, this		As the RPI extension can be ignored by the not-RPL-aware leaf, this
	situation is identical to the previous scenario.		situation is identical to the previous scenario.
	+-------------------+------+-------+----------------+		The Table 3 summarizes what headers are needed for this use case.
	| Header | 6LBR | 6LR_i | IPv6 |
	+-------------------+------+-------+----------------+		+-------------------+----------+-------+----------------+
	| Inserted headers | RPI | -- | -- |		| Header | 6LBR src | 6LR_i | IPv6 dst node |
	| Removed headers | -- | -- | -- |		+-------------------+----------+-------+----------------+
	| Re-added headers | -- | -- | -- |		| Inserted headers | RPI | -- | -- |
	| Modified headers | -- | RPI | -- |		| Removed headers | -- | -- | -- |
	| Untouched headers | -- | -- | RPI (Ignored) |		| Re-added headers | -- | -- | -- |
	+-------------------+------+-------+----------------+		| Modified headers | -- | RPI | -- |
			| Untouched headers | -- | -- | RPI (Ignored) |
			+-------------------+----------+-------+----------------+
	Table 3: Storing: Summary of the use of headers from root to not-RPL-		Table 3: Storing: Summary of the use of headers from root to not-RPL-
	aware-leaf		aware-leaf
	6.1.4. SM: Example of Flow from not-RPL-aware-leaf to root		6.1.4. SM: Example of Flow from not-RPL-aware-leaf to root
	In this case the flow comprises:		In this case the flow comprises:
	not-RPL-aware-leaf (IPv6) --> 6LR_1 --> 6LR_i --> root (6LBR)		not-RPL-aware-leaf (IPv6) --> 6LR_1 --> 6LR_i --> root (6LBR)
	For example, a communication flow could be: Node G --> Node E -->		For example, a communication flow could be: Node G --> Node E -->
	Node B --> Node A root(6LBR)		Node B --> Node A root(6LBR)
	When the packet arrives from IPv6 node (Node G) to 6LR_1 (Node E),		When the packet arrives from IPv6 node (Node G) to 6LR_1 (Node E),
	the 6LR_1 will insert a RPI header, encapsuladed 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
	| Header | IPv | 6LR_1 | 6LR_i | 6LBR |		for this use case. In the figure, IP6-IP6 refers to IPv6-in-IPv6.
	| | 6 | | | |
	+---------+-----+---------------+------------------+----------------+
	| Inserte | -- | IPv6-in- | IPv6-in- | -- |
	| d | | IPv6(RPI) | IPv6(RPI)(1) | |
	| headers | | | | |
	| Removed | -- | -- | -- | IPv6-in- |
	| headers | | | | IPv6(RPI) |
	| Re- | -- | -- | IPv6-in- | -- |
	| added | | | IPv6(RPI)(1) | |
	| headers | | | | |
	| Modifie | -- | -- | IPv6-in- | -- |
	| d | | | IPv6(RPI)(2) | |
	| headers | | | | |
	| Untouch | -- | -- | -- | -- |
	| ed | | | | |
	| headers | | | | |
	+---------+-----+---------------+------------------+----------------+
	Table 4: Storing: Summary of the use of headers from not-RPL-aware-		+-----------+------+--------------+-----------------+--------------------+
	leaf to root. (1) Case where the IPv6-in-IPv6 header is addressed to		| Header | IPv6 | 6LR_1 | 6LR_i | 6LBR dst |
	the next hop (Node B). (2) Case where the IPv6-in-IPv6 header is		| | src | | | |
	addressed to the root (Node A)		| | node | | | |
			+-----------+------+--------------+-----------------+--------------------+
			| Inserted | -- | IP6-IP6(RPI) | IP6-IP6(RPI)[1] | -- |
			| headers | | | | |
			+-----------+------+--------------+-----------------+--------------------+
			| Removed | -- | -- | -- | IP6-IP6(RPI)[1][2] |
			| headers | | | | |
			+-----------+------+--------------+-----------------+--------------------+
			| Re-added | -- | -- | IP6-IP6(RPI)[1] | -- |
			| headers | | | | |
			+-----------+------+--------------+-----------------+--------------------+
			| Modified | -- | -- | IP6-IP6(RPI)[2] | -- |
			| headers | | | | |
			+-----------+------+--------------+-----------------+--------------------+
			| Untouched | -- | -- | -- | -- |
			| headers | | | | |
			+-----------+------+--------------+-----------------+--------------------+
			Figure 8: Storing mode: Summary of the use of headers from not-RPL-
			aware-leaf to root. [[1] Case where the IPv6-in-IPv6 header is
			addressed to the next hop (Node B). [2] Case where the IPv6-in-IPv6
			header is addressed to the root (Node A).
	6.2. Storing Mode: Interaction between Leaf and Internet.		6.2. Storing Mode: Interaction between Leaf and Internet.
	In this section is described the communication flow in storing mode		In this section is described the communication flow in storing mode
	(SM) between,		(SM) between,
	RPL-aware-leaf to Internet		RPL-aware-leaf to Internet
	Internet to RPL-aware-leaf		Internet to RPL-aware-leaf
	skipping to change at page 21, line 12 ¶		skipping to change at page 22, line 12 ¶
	RPL-aware-leaf (6LN) --> 6LR_i --> root (6LBR) --> Internet		RPL-aware-leaf (6LN) --> 6LR_i --> root (6LBR) --> Internet
	For example, the communication flow could be: Node F --> Node D -->		For example, the communication flow could be: Node F --> Node D -->
	Node B --> Node A root(6LBR) --> Internet		Node B --> Node A root(6LBR) --> Internet
	No IPv6-in-IPv6 header is required.		No IPv6-in-IPv6 header is required.
	Note: In this use case it is used a node as leaf, but this use case		Note: In this use case it is used a node as leaf, but this use case
	can be also applicable to any RPL-node type (e.g. 6LR)		can be also applicable to any RPL-node type (e.g. 6LR)
	+-------------------+------+-------+------+----------------+		The Table 4 summarizes what headers are needed for this use case.
	| Header | 6LN | 6LR_i | 6LBR | Internet |
	+-------------------+------+-------+------+----------------+
	| Inserted headers | RPI | -- | -- | -- |
	| Removed headers | -- | -- | -- | -- |
	| Re-added headers | -- | -- | -- | -- |
	| Modified headers | -- | RPI | -- | -- |
	| Untouched headers | -- | -- | RPI | RPI (Ignored) |
	+-------------------+------+-------+------+----------------+
	Table 5: Storing: Summary of the use of headers from RPL-aware-leaf		+-------------------+---------+-------+------+----------------+
			| Header | 6LN src | 6LR_i | 6LBR | Internet dst |
			+-------------------+---------+-------+------+----------------+
			| Inserted headers | RPI | -- | -- | -- |
			| Removed headers | -- | -- | -- | -- |
			| Re-added headers | -- | -- | -- | -- |
			| Modified headers | -- | RPI | -- | -- |
			| Untouched headers | -- | -- | RPI | RPI (Ignored) |
			+-------------------+---------+-------+------+----------------+
			Table 4: Storing: Summary of the use of headers from RPL-aware-leaf
	to Internet		to Internet
	6.2.2. SM: Example of Flow from Internet to RPL-aware-leaf		6.2.2. SM: Example of Flow from Internet to RPL-aware-leaf
	In this case the flow comprises:		In this case the flow comprises:
	Internet --> root (6LBR) --> 6LR_i --> RPL-aware-leaf (6LN)		Internet --> root (6LBR) --> 6LR_i --> RPL-aware-leaf (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 and sent to 6LR, which modifies the		in a outer IPv6-in-IPv6 header (with the IPv6-in-IPv6 destination
	rank in the RPI. When the packet arrives at 6LN the RPI header is		address set to the 6LR) and sent to 6LR, which modifies the rank in
	removed and the packet processed.		the RPI. When the packet arrives at 6LN the RPI header is removed
			and the packet processed.
	+---------+--------+---------------+---------------+----------------+		The Figure 9 shows the table that summarizes what headers are needed
	| Header | Intern | 6LBR | 6LR_i | 6LN |		for this use case. In the figure, IP6-IP6 refers to IPv6-in-IPv6.
	| | et | | | |
	+---------+--------+---------------+---------------+----------------+
	| Inserte | -- | IPv6-in- | -- | -- |
	| d | | IPv6(RPI) | | |
	| headers | | | | |
	| Removed | -- | -- | -- | IPv6-in- |
	| headers | | | | IPv6(RPI) |
	| Re- | -- | -- | -- | -- |
	| added | | | | |
	| headers | | | | |
	| Modifie | -- | -- | IPv6-in- | -- |
	| d | | | IPv6(RPI) | |
	| headers | | | | |
	| Untouch | -- | -- | -- | -- |
	| ed | | | | |
	| headers | | | | |
	+---------+--------+---------------+---------------+----------------+
	Table 6: Storing: Summary of the use of headers from Internet to RPL-		+-----------+----------+--------------+--------------+------------------+
	aware-leaf		| Header | Internet | 6LBR | 6LR_i | 6LN dst |
			| | src | | | |
			+-----------+----------+--------------+--------------+------------------+
			| Inserted | -- | IP6-IP6(RPI) | -- | -- |
			| headers | | | | |
			+-----------+----------+--------------+--------------+------------------+
			| Removed | -- | -- | -- | IP6-IP6(RPI) |
			| headers | | | | |
			+-----------+----------+--------------+--------------+------------------+
			| Re-added | -- | -- | -- | -- |
			| headers | | | | |
			+-----------+----------+--------------+--------------+------------------+
			| Modified | -- | -- | IP6-IP6(RPI) | -- |
			| headers | | | | |
			+-----------+----------+--------------+--------------+------------------+
			| Untouched | -- | -- | -- | -- |
			| headers | | | | |
			+-----------+----------+--------------+--------------+------------------+
			Figure 9: Storing mode: Summary of the use of headers from Internet
			to RPL-aware-leaf.
	6.2.3. SM: Example of Flow from not-RPL-aware-leaf to Internet		6.2.3. SM: Example of Flow from not-RPL-aware-leaf to Internet
	In this case the flow comprises:		In this case the flow comprises:
	not-RPL-aware-leaf (IPv6) --> 6LR_1 --> 6LR_i -->root (6LBR) -->		not-RPL-aware-leaf (IPv6) --> 6LR_1 --> 6LR_i -->root (6LBR) -->
	Internet		Internet
	For example, a communication flow could be: Node G --> Node E -->		For example, a communication flow could be: Node G --> Node E -->
	Node B --> Node A root(6LBR) --> Internet		Node B --> Node A root(6LBR) --> Internet
	skipping to change at page 23, line 5 ¶		skipping to change at page 23, line 51 ¶
	root cause less processing overhead. On the other hand, with hop-by-		root cause less processing overhead. On the other hand, with hop-by-
	hop the intermediate routers can check the routing tables for a		hop the intermediate routers can check the routing tables for a
	better routing path, thus it could be more efficient and faster.		better routing path, thus it could be more efficient and faster.
	Implementation should decide which approach to take.		Implementation should decide which approach to take.
	The originating node will ideally leave the IPv6 flow label as zero		The originating node will ideally leave the IPv6 flow label as zero
	so that the packet can be better compressed through the LLN. The		so that the packet can be better compressed through the LLN. The
	6LBR will set the flow label of the packet to a non-zero value when		6LBR will set the flow label of the packet to a non-zero value when
	sending to the Internet.		sending to the Internet.
	+-------+----+-------------+---------------+---------------+--------+		The Figure 10 shows the table that summarizes what headers are needed
	| Heade | IP | 6LR_1 | 6LR_i | 6LBR | Intern |		for this use case. In the figure, IP6-IP6 refers to IPv6-in-IPv6.
	| r | v6 | | [i=2,..,n]_ | | et |
	+-------+----+-------------+---------------+---------------+--------+
	| Inser | -- | IPv6-in- | IPv6-in- | -- | -- |
	| ted h | | IPv6(RPI) | IPv6(RPI)(2) | | |
	| eader | | | | | |
	| s | | | | | |
	| Remov | -- | -- | IPv6-in- | IPv6-in- | -- |
	| ed he | | | IPv6(RPI)(2) | IPv6(RPI)(1) | |
	| aders | | | | | |
	| Re- | -- | -- | -- | -- | -- |
	| added | | | | | |
	| heade | | | | | |
	| rs | | | | | |
	| Modif | -- | -- | IPv6-in- | -- | -- |
	| ied h | | | IPv6(RPI)(1) | | |
	| eader | | | | | |
	| s | | | | | |
	| Untou | -- | -- | -- | -- | -- |
	| ched | | | | | |
	| heade | | | | | |
	| rs | | | | | |
	+-------+----+-------------+---------------+---------------+--------+
	Table 7: Storing: Summary of the use of headers from not-RPL-aware-		+---------+-------+------------+--------------+-------------+--------+
	leaf to Internet. (1) Case when packet is addressed to the root.		| Header | IPv6 | 6LR_1 | 6LR_i | 6LBR |Internet|
	(2) Case when the packet is addressed hop-by-hop.		| | src | | [i=2,...,n] | | dst |
			| | node | | | | |
			+---------+-------+------------+--------------+-------------+--------+
			| Inserted| -- |IP6-IP6(RPI)| IP6-IP6(RPI) | -- | -- |
			| headers | | | [2] | | |
			+---------+-------+------------+--------------+-------------+--------+
			| Removed | -- | -- | IP6-IP6(RPI) | IP6-IP6(RPI)| -- |
			| headers | | | [2] | [1][2] | |
			+---------+-------+------------+--------------+-------------+--------+
			| Re-added| -- | -- | -- | -- | -- |
			| headers | | | | | |
			+---------+-------+------------+--------------+-------------+--------+
			| Modified| -- | -- | IP6-IP6(RPI) | -- | -- |
			| headers | | | [1] | | |
			+---------+-------+------------+--------------+-------------+--------+
			|Untouched| -- | -- | -- | -- | -- |
			| headers | | | | | |
			+---------+-------+------------+--------------+-------------+--------+
	6.2.4. SM: Example of Flow from Internet to non-RPL-aware-leaf.		Figure 10: Storing mode: Summary of the use of headers from not-RPL-
			aware-leaf to Internet. [1] Case when packet is addressed to the
			root. [2] Case when the packet is addressed hop-by-hop.
			6.2.4. SM: Example of Flow from Internet to not-RPL-aware-leaf.
	In this case the flow comprises:		In this case the flow comprises:
	Internet --> root (6LBR) --> 6LR_i --> not-RPL-aware-leaf (IPv6)		Internet --> root (6LBR) --> 6LR_i --> not-RPL-aware-leaf (IPv6)
	For example, a communication flow could be: Internet --> Node A		For example, a communication flow could be: Internet --> Node A
	root(6LBR) --> Node B --> Node E --> Node G		root(6LBR) --> Node B --> Node E --> Node G
	The 6LBR will have to add an RPI header within an IPv6-in-IPv6		The 6LBR will have to add an RPI header within an IPv6-in-IPv6
	header. The IPv6-in-IPv6 is addressed to the not-RPL-aware-leaf,		header. The IPv6-in-IPv6 is addressed hop-by-hop.
	leaving the RPI inside.
	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. Furhter details about this		headers which are all addressed to it. The final node does not
	are mentioned in [I-D.thubert-roll-unaware-leaves], which specifies		process the RPI, the node ignores the RPI. Furhter details about
	RPL routing for a 6LN acting as a plain host and not aware of RPL.		this are mentioned in [I-D.thubert-roll-unaware-leaves], which
			specifies RPL routing for a 6LN acting as a plain host and not aware
			of RPL.
	The 6LBR may set the flow label on the inner IPv6-in-IPv6 header to		The 6LBR may set the flow label on the inner IPv6-in-IPv6 header to
	zero in order to aid in compression.		zero in order to aid in compression.
	+--------+---------+---------------+---------------+----------------+		The Figure 11 shows the table that summarizes what headers are needed
	| Header | Interne | 6LBR | 6LR_i | IPv6 |		for this use case. In the figure, IP6-IP6 refers to IPv6-in-IPv6.
	| | t | | | |
	+--------+---------+---------------+---------------+----------------+
	| Insert | -- | IPv6-in- | -- | -- |
	| ed hea | | IPv6(RPI) | | |
	| ders | | | | |
	| Remove | -- | -- | -- | IPv6-in- |
	| d head | | | | IPv6(RPI)- RPI |
	| ers | | | | (Ignored) |
	| Re- | -- | -- | -- | -- |
	| added | | | | |
	| header | | | | |
	| s | | | | |
	| Modifi | -- | -- | IPv6-in- | -- |
	| ed hea | | | IPv6(RPI) | |
	| ders | | | | |
	| Untouc | -- | -- | -- | -- |
	| hed he | | | | |
	| aders | | | | |
	+--------+---------+---------------+---------------+----------------+
	Table 8: Storing: Summary of the use of headers from Internet to non-		+-----------+----------+--------------+--------------+--------------+
	RPL-aware-leaf		| Header | Internet | 6LBR | 6LR_i |IPv6 dst node |
			| | src | | | |
			+-----------+----------+--------------+--------------+--------------+
			| Inserted | -- | IP6-IP6(RPI) | -- | -- |
			| headers | | | | |
			+-----------+----------+--------------+--------------+--------------+
			| Removed | -- | -- | | IP6-IP6(RPI)|
			| headers | | | | RPI Ignored |
			+-----------+----------+--------------+--------------+--------------+
			| Re-added | -- | -- | -- | -- |
			| headers | | | | |
			+-----------+----------+--------------+--------------+--------------+
			| Modified | -- | -- | IP6-IP6(RPI) | -- |
			| headers | | | | |
			+-----------+----------+--------------+--------------+--------------+
			| Untouched | -- | -- | -- | -- |
			| headers | | | | |
			+-----------+----------+--------------+--------------+--------------+
			Figure 11: Storing mode: Summary of the use of headers from Internet
			to not-RPL-aware-leaf.
	6.3. Storing Mode: Interaction between Leaf and Leaf		6.3. Storing Mode: Interaction between Leaf and Leaf
	In this section is described the communication flow in storing mode		In this section is described the communication flow in storing mode
	(SM) between,		(SM) between,
	RPL-aware-leaf to RPL-aware-leaf		RPL-aware-leaf to RPL-aware-leaf
	RPL-aware-leaf to not-RPL-aware-leaf		RPL-aware-leaf to not-RPL-aware-leaf
	skipping to change at page 25, line 13 ¶		skipping to change at page 26, line 10 ¶
	[RFC6550].		[RFC6550].
	When the nodes are not directly connected, then in storing mode, the		When the nodes are not directly connected, then in storing mode, the
	flow comprises:		flow comprises:
	6LN --> 6LR_ia --> common parent (6LR_x) --> 6LR_id --> 6LN		6LN --> 6LR_ia --> common parent (6LR_x) --> 6LR_id --> 6LN
	For example, a communication flow could be: Node F --> Node D -->		For example, a communication flow could be: Node F --> Node D -->
	Node B --> Node E --> Node H		Node B --> Node E --> Node H
	6LR_ia (Node D) are the intermediate routers from source to the		6LR_ia (Node D) is the intermediate router from source to the common
	common parent (6LR_x) (Node B) In this case, "1 <= ia <= n", n is the		parent (6LR_x) (Node B) In this case, "1 <= ia <= n", n is the number
	number of routers (6LR) that the packet go through from 6LN (Node F)		of routers (6LR) that the packet goes through from 6LN (Node F) to
	to the common parent (6LR_x).		the common parent (6LR_x).
	6LR_id (Node E) are the intermediate routers from the common parent		6LR_id (Node E) is the intermediate router from the common parent
	(6LR_x) (Node B) to destination 6LN (Node H). In this case, "1 <= id		(6LR_x) (Node B) to destination 6LN (Node H). In this case, "1 <= id
	<= m", m is the number of routers (6LR) that the packet go through		<= m", m is the number of routers (6LR) that the packet goes through
	from the common parent (6LR_x) to destination 6LN.		from the common parent (6LR_x) to destination 6LN.
	It is assumed that the two nodes are in the same RPL Domain (that		It is assumed that the two nodes are in the same RPL Domain (that
	they share the same DODAG root). At the common parent (Node B), the		they share the same DODAG root). At the common parent (Node B), the
	direction of RPI is changed (from increasing to decreasing the rank).		direction of RPI is changed (from increasing to decreasing the rank).
	While the 6LR nodes will update the RPI, no node needs to add or		While the 6LR nodes will update the RPI, no node needs to add or
	remove the RPI, so no IPv6-in-IPv6 headers are necessary. This may		remove the RPI, so no IPv6-in-IPv6 headers are necessary.
	be done regardless of where the destination is, as the included RPI
	will be ignored by the receiver.		The Table 5 summarizes what headers are needed for this use case.
	+---------------+--------+--------+---------------+--------+--------+		+---------------+--------+--------+---------------+--------+--------+
	| Header | 6LN | 6LR_ia | 6LR_x (common | 6LR_id | 6LN |		| Header | 6LN | 6LR_ia | 6LR_x (common | 6LR_id | 6LN |
	| | 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 9: Storing: Summary of the use of headers for RPL-aware-leaf to		Table 5: Storing: Summary of the use of headers for RPL-aware-leaf to
	RPL-aware-leaf		RPL-aware-leaf
	6.3.2. SM: Example of Flow from RPL-aware-leaf to non-RPL-aware-leaf		6.3.2. SM: Example of Flow from RPL-aware-leaf to not-RPL-aware-leaf
	In this case the flow comprises:		In this case the flow comprises:
	6LN --> 6LR_ia --> common parent (6LR_x) --> 6LR_id --> not-RPL-aware		6LN --> 6LR_ia --> common parent (6LR_x) --> 6LR_id --> not-RPL-aware
	6LN (IPv6)		6LN (IPv6)
	For example, a communication flow could be: Node F --> Node D -->		For example, a communication flow could be: Node F --> Node D -->
	Node B --> Node E --> Node G		Node B --> Node E --> Node G
	6LR_ia are the intermediate routers from source (6LN) to the common		6LR_ia is the intermediate router from source (6LN) to the common
	parent (6LR_x) In this case, "1 <= ia <= n", n is the number of		parent (6LR_x) In this case, "1 <= ia <= n", n is the number of
	routers (6LR) that the packet go through from 6LN to the common		routers (6LR) that the packet goes through from 6LN to the common
	parent (6LR_x).		parent (6LR_x).
	6LR_id (Node E) are the intermediate routers from the common parent		6LR_id (Node E) is the intermediate router from the common parent
	(6LR_x) (Node B) to destination not-RPL-aware 6LN (IPv6) (Node G).		(6LR_x) (Node B) to destination not-RPL-aware 6LN (IPv6) (Node G).
	In this case, "1 <= id <= m", m is the number of routers (6LR) that		In this case, "1 <= id <= m", m is the number of routers (6LR) that
	the packet go through from the common parent (6LR_x) to destination		the packet goes through from the common parent (6LR_x) to destination
	6LN.		6LN.
	This situation is identical to the previous situation Section 6.3.1		This situation is identical to the previous situation Section 6.3.1
			The Table 6 summarizes what headers are needed for this use case.
	+-----------+------+--------+---------------+--------+--------------+		+-----------+------+--------+---------------+--------+--------------+
	| Header | 6LN | 6LR_ia | 6LR_x(common | 6LR_id | IPv6 |		| Header | 6LN | 6LR_ia | 6LR_x(common | 6LR_id | IPv6 dst |
	| | src | | parent) | | |		| | src | | parent) | | node |
	+-----------+------+--------+---------------+--------+--------------+		+-----------+------+--------+---------------+--------+--------------+
	| Inserted | RPI | -- | -- | -- | -- |		| Inserted | RPI | -- | -- | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	| Removed | -- | -- | -- | -- | -- |		| Removed | -- | -- | -- | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	| Re-added | -- | -- | -- | -- | -- |		| Re-added | -- | -- | -- | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	| Modified | -- | RPI | RPI | RPI | -- |		| Modified | -- | RPI | RPI | RPI | -- |
	| headers | | | | | |		| headers | | | | | |
	| Untouched | -- | -- | -- | -- | RPI(Ignored) |		| Untouched | -- | -- | -- | -- | RPI(Ignored) |
	| headers | | | | | |		| headers | | | | | |
	+-----------+------+--------+---------------+--------+--------------+		+-----------+------+--------+---------------+--------+--------------+
	Table 10: Storing: Summary of the use of headers for RPL-aware-leaf		Table 6: Storing: Summary of the use of headers for RPL-aware-leaf to
	to non-RPL-aware-leaf		not-RPL-aware-leaf
	6.3.3. SM: Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf		6.3.3. SM: Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf
	In this case the flow comprises:		In this case the flow comprises:
	not-RPL-aware 6LN (IPv6) --> 6LR_ia --> common parent (6LR_x) -->		not-RPL-aware 6LN (IPv6) --> 6LR_ia --> common parent (6LR_x) -->
	6LR_id --> 6LN		6LR_id --> 6LN
	For example, a communication flow could be: Node G --> Node E -->		For example, a communication flow could be: Node G --> Node E -->
	Node B --> Node D --> Node F		Node B --> Node D --> Node F
	6LR_ia (Node E) are the intermediate routers from source (not-RPL-		6LR_ia (Node E) is the intermediate router from source (not-RPL-aware
	aware 6LN (IPv6)) (Node G) to the common parent (6LR_x) (Node B). In		6LN (IPv6)) (Node G) to the common parent (6LR_x) (Node B). In this
	this case, "1 <= ia <= n", n is the number of routers (6LR) that the		case, "1 <= ia <= n", n is the number of routers (6LR) that the
	packet go through from source to the common parent.		packet ges through from source to the common parent.
	6LR_id (Node D) are the intermediate routers from the common parent		6LR_id (Node D) is the intermediate router from the common parent
	(6LR_x) (Node B) to destination 6LN (Node F). In this case, "1 <= id		(6LR_x) (Node B) to destination 6LN (Node F). In this case, "1 <= id
	<= m", m is the number of routers (6LR) that the packet go through		<= m", m is the number of routers (6LR) that the packet goes through
	from the common parent (6LR_x) to destination 6LN.		from the common parent (6LR_x) to destination 6LN.
	The 6LR_ia (ia=1) (Node E) receives the packet from the the IPv6 node		The 6LR_ia (ia=1) (Node E) receives the packet from the the IPv6 node
	(Node G) and inserts and the RPI header encapsulated in IPv6-in-IPv6		(Node G) and inserts and the RPI header encapsulated in IPv6-in-IPv6
	header. The IPv6-in-IPv6 header is addressed to the destination 6LN		header. The IPv6-in-IPv6 header is addressed to the destination 6LN
	(Node F).		(Node F).
	+-------+----+------------+-------------+-------------+-------------+		The Figure 12 shows the table that summarizes what headers are needed
	| Heade | IP | 6LR_ia | common | 6LR_id | 6LN |		for this use case. In the figure, IP6-IP6 refers to IPv6-in-IPv6.
	| r | v6 | | parent | | |
	| | | | (6LRx) | | |
	+-------+----+------------+-------------+-------------+-------------+
	| Inser | -- | IPv6-in- | -- | -- | -- |
	| ted h | | IPv6(RPI) | | | |
	| eader | | | | | |
	| s | | | | | |
	| Remov | -- | -- | -- | -- | IPv6-in- |
	| ed he | | | | | IPv6(RPI) |
	| aders | | | | | |
	| Re- | -- | -- | -- | -- | -- |
	| added | | | | | |
	| heade | | | | | |
	| rs | | | | | |
	| Modif | -- | -- | IPv6-in- | IPv6-in- | -- |
	| ied h | | | IPv6(RPI) | IPv6(RPI) | |
	| eader | | | | | |
	| s | | | | | |
	| Untou | -- | -- | -- | -- | -- |
	| ched | | | | | |
	| heade | | | | | |
	| rs | | | | | |
	+-------+----+------------+-------------+-------------+-------------+
	Table 11: Storing: Summary of the use of headers from not-RPL-aware-		+----------+-----+--------------+--------------+--------------+------------+
	leaf to RPL-aware-leaf		| Header |IPv6 | 6LR_ia | Common | 6LR_id | 6LN |
			| |src | | Parent | | dst |
			| |node | | (6LRx) | | |
			+----------+-----+--------------+--------------+--------------+------------+
			| Inserted | -- | IP6-IP6(RPI) | -- | -- | -- |
			| headers | | | | | |
			+----------+-----+--------------+--------------+--------------+------------+
			| Removed | -- | -- | -- | -- |IP6-IP6(RPI)|
			| headers | | | | | |
			+----------+-----+--------------+--------------+--------------+------------+
			| Re-added | -- | -- | -- | -- | -- |
			| headers | | | | | |
			+----------+-----+--------------+--------------+--------------+------------+
			| Modified | -- | -- | IP6-IP6(RPI) | IP6-IP6(RPI) | -- |
			| headers | | | | | |
			+----------+-----+--------------+--------------+--------------+------------+
			|Untouched | -- | -- | -- | -- | -- |
			| headers | | | | | |
			+----------+-----+--------------+--------------+--------------+------------+
			Figure 12: Storing mode: Summary of the use of headers from not-RPL-
			aware-leaf to RPL-aware-leaf.
	6.3.4. SM: Example of Flow from not-RPL-aware-leaf to not-RPL-aware-		6.3.4. SM: Example of Flow from not-RPL-aware-leaf to not-RPL-aware-
	leaf		leaf
	In this case the flow comprises:		In this case the flow comprises:
	not-RPL-aware 6LN (IPv6 src)--> 6LR_1--> 6LR_ia --> 6LR_id --> not-		not-RPL-aware 6LN (IPv6 src)--> 6LR_1--> 6LR_ia --> 6LBR --> 6LR_id
	RPL-aware 6LN (IPv6 dst)		--> not-RPL-aware 6LN (IPv6 dst)
	For example, a communication flow could be: Node G --> Node E -->		For example, a communication flow could be: Node G --> Node E -->
	Node B --> Node A (root) --> Node C --> Node J		Node B --> Node A (root) --> Node C --> Node J
	Internal nodes 6LR_ia (e.g: Node E or Node B) are the intermediate		Internal nodes 6LR_ia (e.g: Node E or Node B) is the intermediate
	routers from the not-RPL-aware source (Node G) to the root (6LBR)		router from the not-RPL-aware source (Node G) to the root (6LBR)
	(Node A). In this case, "1 < ia <= n", n is the number of routers		(Node A). In this case, "1 < ia <= n", n is the number of routers
	(6LR) that the packet go through from IPv6 src to the root.		(6LR) that the packet goes through from IPv6 src to the root.
	6LR_id (C) are the intermediate routers from the root (Node A) to the		6LR_id (C) is the intermediate router from the root (Node A) to the
	destination Node J. In this case, "1 <= id <= m", m is the number of		destination Node J. In this case, "1 <= id <= m", m is the number of
	routers (6LR) that the packet go through from the root to destination		routers (6LR) that the packet goes through from the root to
	(IPv6 dst).		destination (IPv6 dst).
	Note that this flow is identical to Section 6.3.3, except for where		Note that this flow is identical to Section 6.3.3, except that the
	the IPv6-in-IPv6 header is inserted.		RPI is ignored at the IPv6 dst node.
	The 6LR_1 (Node E) receives the packet from the the IPv6 node (Node		The 6LR_1 (Node E) receives the packet from the the IPv6 node (Node
	G) and inserts the RPI header (RPI), encapsulated in an IPv6-in-IPv6		G) and inserts the RPI header (RPI), encapsulated in an IPv6-in-IPv6
	header. The IPv6-in-IPv6 header is addressed to the final		header. The IPv6-in-IPv6 header is addressed to the final
	destination (Node J).		destination (Node J).
	+-------+----+------------+-------------+-------------+-------------+		The Figure 13 shows the table that summarizes what headers are needed
	| Heade | IP | 6LR_1 | 6LR_ia | 6LR_m | IPv6 dst |		for this use case. In the figure, IP6-IP6 refers to IPv6-in-IPv6.
	| r | v6 | | | | |
	| | sr | | | | |
	| | c | | | | |
	+-------+----+------------+-------------+-------------+-------------+
	| Inser | -- | IPv6-in- | -- | -- | -- |
	| ted h | | IPv6(RPI) | | | |
	| eader | | | | | |
	| s | | | | | |
	| Remov | -- | -- | -- | -- | IPv6-in- |
	| ed he | | | | | IPv6(RPI), |
	| aders | | | | | RPI Ignored |
	| Re- | -- | -- | -- | -- | -- |
	| added | | | | | |
	| heade | | | | | |
	| rs | | | | | |
	| Modif | -- | -- | IPv6-in- | IPv6-in- | -- |
	| ied h | | | IPv6(RPI) | IPv6(RPI) | |
	| eader | | | | | |
	| s | | | | | |
	| Untou | -- | -- | -- | -- | -- |
	| ched | | | | | |
	| heade | | | | | |
	| rs | | | | | |
	+-------+----+------------+-------------+-------------+-------------+
	Table 12: Storing: Summary of the use of headers from not-RPL-aware-		+---------+------+------------+------------+------------+------------+
	leaf to non-RPL-aware-leaf		| Header | IPv6 | 6LR_1 | 6LR_ia | 6LR_m | IPv6 |
			| | src | | | | dst |
			| | node | | | | node |
			+---------+------+------------+------------+------------+------------+
			| Inserted| -- |IP6-IP6(RPI)| -- | -- | -- |
			| headers | | | | | |
			+---------+------+------------+------------+------------+------------+
			| Removed | -- | -- | -- | -- |IP6-IP6(RPI)|
			| headers | | | | | RPI Ignored|
			+---------+------+------------+------------+------------+------------+
			| Re-added| -- | -- | -- | -- | -- |
			| headers | | | | | |
			+---------+------+------------+------------+------------+------------+
			| Modified| -- | -- |IP6-IP6(RPI)|IP6-IP6(RPI)| -- |
			| headers | | | | | |
			+---------+------+------------+------------+------------+------------+
			|Untouched| -- | -- | -- | -- | -- |
			| headers | | | | | |
			+---------+------+------------+------------+------------+------------+
			Figure 13: Storing mode: Summary of the use of headers from not-RPL-
			aware-leaf to not-RPL-aware-leaf
	7. Non Storing mode		7. 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 non-RPL aware		no need for all nodes to know about the existence of not-RPL aware
	nodes. Only the 6LBR needs to act if compensation is necessary for		nodes. Only the 6LBR needs to act if compensation is necessary for
	non-RPL aware receivers.		not-RPL aware receivers.
	The following table (Figure 8) summarizes what headers are needed in		The following table (Figure 14) summarizes what headers are needed in
	the following scenarios, and indicates when the RPI, RH3 and IPv6-in-		the following scenarios, and indicates when the RPI, RH3 and IPv6-in-
	IPv6 header are to be inserted. There are these possible situations:		IPv6 header are to be inserted. It depicts the target destination
	target destination address possible (indicated by "tgt"), to a 6LR,		address possible (indicated by "Raf"), to a 6LR (parent of a 6LN) or
	to a 6LN or to the root. In cases where no IPv6-in-IPv6 header is		to the root. In cases where no IPv6-in-IPv6 header is needed, the
	needed, the column states as "No".		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
			compression. This specification expects that is always a RPI
			Present.
	The leaf can be a router 6LR or a host, both indicated as 6LN		The leaf can be a router 6LR or a host, both indicated as 6LN
	(Figure 3). In the Figure the (1) indicates a 6tisch case [RFC8180],		(Figure 3). In the Figure the (1) indicates a 6tisch case [RFC8180],
	where the instanceID portion of the RPI header may still be needed to		where the RPI header may still be needed for the instanceID to be
	pick an appropriate priority or channel at each hop.		available for priority/channel selection at each hop.
	+-----------------+--------------+-----+-----+----------+----------+
	| Interaction | Use Case | RPI | RH3 | v6-in-v6 | v6-in-v6 |
	| between | | | | | dst |
	+-----------------+--------------+-----+-----+----------+----------+
	| | Raf to root | Yes | No | No | No |
	+ +--------------+-----+-----+----------+----------+
	| Leaf - Root | root to Raf | Opt | Yes | No | No |
	+ +--------------+-----+-----+----------+----------+
	| | root to ~Raf |No(1)| Yes | must | 6LR |
	+ +--------------+-----+-----+----------+----------+
	| | ~Raf to root | Yes | No | must | root |
	+-----------------+--------------+-----+-----+----------+----------+
	| | Raf to Int | Yes | No | must | root |
	+ +--------------+-----+-----+----------+----------+
	| Leaf - Internet | Int to Raf |No(1)| Yes | must | tgt |
	+ +--------------+-----+-----+----------+----------+
	| | ~Raf to Int | Yes | No | must | root |
	+ +--------------+-----+-----+----------+----------+
	| | Int to ~Raf |No(1)| Yes | must | 6LR |
	+-----------------+--------------+-----+-----+----------+----------+
	| | Raf to Raf | Yes | Yes | must | root/tgt |
	+ +--------------+-----+-----+----------+----------+
	| | Raf to ~Raf | Yes | Yes | must | root/6LR |
	+ Leaf - Leaf +--------------+-----+-----+----------+----------+
	| | ~Raf to Raf | Yes | Yes | must | root/6LN |
	+ +--------------+-----+-----+----------+----------+
	| | ~Raf to ~Raf | Yes | Yes | must | root/6LR |
	+-----------------+--------------+-----+-----+----------+----------+
	(1)-6tisch networks may need the RPI information.		+-----------------+--------------+-----+-----+------------+------------+
			| Interaction | Use Case | RPI | RH3 |IPv6-in-IPv6|IPv6-in-IPv6|
			| between | | | | | dst |
			+-----------------+--------------+-----+-----+------------+------------+
			| | Raf to root | Yes | No | No | No |
			+ +--------------+-----+-----+------------+------------+
			| Leaf - Root | root to Raf | Yes | Yes | No | No |
			+ +--------------+-----+-----+------------+------------+
			| | root to ~Raf | Yes | Yes | must | 6LR |
			| | | (1) | | | |
			+ +--------------+-----+-----+------------+------------+
			| | ~Raf to root | Yes | No | must | root |
			+-----------------+--------------+-----+-----+------------+------------+
			| | Raf to Int | Yes | No | No | No |
			+ +--------------+-----+-----+------------+------------+
			| Leaf - Internet | Int to Raf | Yes | Yes | must | Raf |
			+ +--------------+-----+-----+------------+------------+
			| | ~Raf to Int | Yes | No | must | root |
			+ +--------------+-----+-----+------------+------------+
			| | Int to ~Raf | Yes | Yes | must | 6LR |
			+-----------------+--------------+-----+-----+------------+------------+
			| | Raf to Raf | Yes | Yes | must | root/Raf |
			+ +--------------+-----+-----+------------+------------+
			| | Raf to ~Raf | Yes | Yes | must | root/6LR |
			+ Leaf - Leaf +--------------+-----+-----+------------+------------+
			| | ~Raf to Raf | Yes | Yes | must | root/Raf |
			+ +--------------+-----+-----+------------+------------+
			| | ~Raf to ~Raf | Yes | Yes | must | root/6LR |
			+-----------------+--------------+-----+-----+------------+------------+
	Figure 8: Table that shows headers needed in Non-Storing mode: RPI,		Figure 14: Table that shows headers needed in Non-Storing mode: RPI,
	RH3, IPv6-in-IPv6 encapsulation.		RH3, IPv6-in-IPv6 encapsulation.
	7.1. Non-Storing Mode: Interaction between Leaf and Root		7.1. Non-Storing Mode: Interaction between Leaf and Root
	In this section is described the communication flow in Non Storing		In this section is described the communication flow in Non Storing
	Mode (Non-SM) between,		Mode (Non-SM) between,
	RPL-aware-leaf to root		RPL-aware-leaf to root
	root to RPL-aware-leaf		root to RPL-aware-leaf
	skipping to change at page 31, line 4 ¶		skipping to change at page 31, line 48 ¶
	7.1. Non-Storing Mode: Interaction between Leaf and Root		7.1. Non-Storing Mode: Interaction between Leaf and Root
	In this section is described the communication flow in Non Storing		In this section is described the communication flow in Non Storing
	Mode (Non-SM) between,		Mode (Non-SM) between,
	RPL-aware-leaf to root		RPL-aware-leaf to root
	root to RPL-aware-leaf		root to RPL-aware-leaf
	not-RPL-aware-leaf to root		not-RPL-aware-leaf to root
	root to not-RPL-aware-leaf		root to not-RPL-aware-leaf
	7.1.1. Non-SM: Example of Flow from RPL-aware-leaf to root		7.1.1. Non-SM: Example of Flow from RPL-aware-leaf to root
	In non-storing mode the leaf node uses default routing to send		In non-storing mode the leaf node uses default routing to send
	traffic to the root. The RPI header must be included since it		traffic to the root. The RPI header must be included since it
	contains the rank information, which is used to avoid/detect loops.		contains the rank information, which is used to avoid/detect loops.
	RPL-aware-leaf (6LN) --> 6LR_i --> root(6LBR)		RPL-aware-leaf (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 is the intermediate router from source to destination. In this
	this case, "1 <= i <= n", n is the number of routers (6LR) that the		case, "1 <= i <= n", n is the number of routers (6LR) that the packet
	packet go through from source (6LN) to destination (6LBR).		goes through from source (6LN) to destination (6LBR).
	This situation is the same case as storing mode.		This situation is the same case as storing mode.
	+-------------------+-----+-------+------+		The Table 7 summarizes what headers are needed for this use case.
	| Header | 6LN | 6LR_i | 6LBR |
	+-------------------+-----+-------+------+
	| Inserted headers | RPI | -- | -- |
	| Removed headers | -- | -- | RPI |
	| Re-added headers | -- | -- | -- |
	| Modified headers | -- | RPI | -- |
	| Untouched headers | -- | -- | -- |
	+-------------------+-----+-------+------+
	Table 13: Non Storing: Summary of the use of headers from RPL-aware-		+-------------------+---------+-------+----------+
			| Header | 6LN src | 6LR_i | 6LBR dst |
			+-------------------+---------+-------+----------+
			| Inserted headers | RPI | -- | -- |
			| Removed headers | -- | -- | RPI |
			| Re-added headers | -- | -- | -- |
			| Modified headers | -- | RPI | -- |
			| Untouched headers | -- | -- | -- |
			+-------------------+---------+-------+----------+
			Table 7: Non Storing: Summary of the use of headers from RPL-aware-
	leaf to root		leaf to root
	7.1.2. Non-SM: Example of Flow from root to RPL-aware-leaf		7.1.2. Non-SM: Example of Flow from root to RPL-aware-leaf
	In this case the flow comprises:		In this case the flow comprises:
	root (6LBR) --> 6LR_i --> RPL-aware-leaf (6LN)		root (6LBR) --> 6LR_i --> RPL-aware-leaf (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 is the intermediate router from source to destination. In this
	this case, "1 <= i <= n", n is the number of routers (6LR) that the		case, "1 <= i <= n", n is the number of routers (6LR) that the packet
	packet go through from source (6LBR) to destination (6LN).		goes through from source (6LBR) to destination (6LN).
	The 6LBR inserts an RH3, and a RPI header. No IPv6-in-IPv6 header is		The 6LBR inserts an RH3, and a RPI header. No IPv6-in-IPv6 header is
	necessary as the traffic originates with an RPL aware node, the 6LBR.		necessary as the traffic originates with an RPL aware node, the 6LBR.
	The destination is known to 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.
	| Header | 6LBR | 6LR_i | 6LN |
	+-------------------+-----------------+-------+------------------+
	| Inserted headers | (opt: RPI), RH3 | -- | -- |
	| Removed headers | -- | -- | RH3, (opt: RPI) |
	| Re-added headers | -- | -- | -- |
	| Modified headers | -- | RH3 | -- |
	| Untouched headers | -- | -- | -- |
	+-------------------+-----------------+-------+------------------+
	Table 14: Non Storing: Summary of the use of headers from root to		+-------------------+----------+-----------+-----------+
	RPL-aware-leaf		| Header | 6LBR src | 6LR_i | 6LN dst |
			+-------------------+----------+-----------+-----------+
			| Inserted headers | RPI, RH3 | -- | -- |
			| Removed headers | -- | -- | RH3, RPI |
			| Re-added headers | -- | -- | -- |
			| Modified headers | -- | RPI, RH3 | -- |
			| Untouched headers | -- | -- | -- |
			+-------------------+----------+-----------+-----------+
			Table 8: Non Storing: Summary of the use of headers from root to RPL-
			aware-leaf
	7.1.3. Non-SM: Example of Flow from root to not-RPL-aware-leaf		7.1.3. Non-SM: Example of Flow from root to not-RPL-aware-leaf
	In this case the flow comprises:		In this case the flow comprises:
	root (6LBR) --> 6LR_i --> not-RPL-aware-leaf (IPv6)		root (6LBR) --> 6LR_i --> not-RPL-aware-leaf (IPv6)
	For example, a communication flow could be: Node A (root) --> Node B		For example, a communication flow could be: Node A (root) --> Node B
	--> Node E --> Node G		--> Node E --> Node G
	6LR_i are the intermediate routers from source to destination. In		6LR_i is the intermediate router from source to destination. In this
	this case, "1 <= i <= n", n is the number of routers (6LR) that the		case, "1 <= i <= n", n is the number of routers (6LR) that the packet
	packet go through from source (6LBR) to destination (IPv6).		goes through from source (6LBR) to destination (IPv6).
	In 6LBR the RH3 is added, it is modified at each intermediate 6LR		In 6LBR the RH3 is added, it is modified at each intermediate 6LR
	(6LR_1 and so on) and it is fully consumed in the last 6LR (6LR_n),		(6LR_1 and so on) and it is fully consumed in the last 6LR (6LR_n),
	but left there. If RPI is left by the previous 6LR, then the IPv6		but left there. As the RPI is added, then the IPv6 node which does
	node which does not understand the RPI, will ignore it (following		not understand the RPI, will ignore it (following RFC8200), thus
	RFC8200), thus encapsulation is not necessary. Due to the complete		encapsulation is not necessary.
	knowledge of the topology at the root, the 6LBR may optionally
	address the IPv6-in-IPv6 header to the last 6LR, such that it is
	removed prior to the IPv6 node. Please see Section 8 for
	clarification of use of IPv6-in-IPv6 encapsulation.
	+---------------+-------------+--------------+------------+---------+		The Figure 15 depicts the table that summarizes what headers are
	| Header | 6LBR | 6LR_i(i=1) | 6LR_n(i=n) | IPv6 |		needed for this use case.
	+---------------+-------------+--------------+------------+---------+
	| Inserted | (opt: RPI), | -- | -- | -- |
	| headers | RH3 | | | |
	| Removed | -- | -- | RH3 | -- |
	| headers | | | | |
	| Re-added | -- | -- | -- | -- |
	| headers | | | | |
	| Modified | -- | (opt: RPI), | (opt: RPI) | -- |
	| headers | | RH3 | | |
	| Untouched | -- | -- | -- | opt: |
	| headers | | | | RPI |
	+---------------+-------------+--------------+------------+---------+
	Table 15: Non Storing: Summary of the use of headers from root to		+-----------+----------+--------------+----------------+----------+
			| Header | 6LBR | 6LR_i | 6LR_n | IPv6 |
			| | | i=(1,..,n-1) | | dst |
			| | | | | node |
			+-----------+----------+--------------+----------------+----------+
			| Inserted | RPI, RH3 | -- | -- | -- |
			| headers | | | | |
			+-----------+----------+--------------+----------------+----------+
			| Removed | -- | -- | | -- |
			| headers | | | | |
			+-----------+----------+--------------+----------------+----------+
			| Re-added | -- | -- | -- | -- |
			| headers | | | | |
			+-----------+----------+--------------+----------------+----------+
			| Modified | -- | RPI, RH3 | RPI, | -- |
			| headers | | | RH3(consumed) | |
			+-----------+----------+--------------+----------------+----------+
			| Untouched | -- | -- | -- | RPI, RH3 |
			| headers | | | | (both |
			| | | | | ignored) |
			+-----------+----------+--------------+----------------+----------+
			Figure 15: Non Storing: Summary of the use of headers from root to
	not-RPL-aware-leaf		not-RPL-aware-leaf
	7.1.4. Non-SM: Example of Flow from not-RPL-aware-leaf to root		7.1.4. Non-SM: Example of Flow from not-RPL-aware-leaf to root
	In this case the flow comprises:		In this case the flow comprises:
	not-RPL-aware-leaf (IPv6) --> 6LR_1 --> 6LR_i --> root (6LBR)		not-RPL-aware-leaf (IPv6) --> 6LR_1 --> 6LR_i --> root (6LBR)
	For example, a communication flow could be: Node G --> Node E -->		For example, a communication flow could be: Node G --> Node E -->
	Node B --> Node A (root)		Node B --> Node A (root)
	6LR_i are the intermediate routers from source to destination. In		6LR_i is the intermediate router from source to destination. In this
	this case, "1 < i <= n", n is the number of routers (6LR) that the		case, "1 < i <= n", n is the number of routers (6LR) that the packet
	packet go through from source (IPv6) to destination (6LBR). For		goes through from source (IPv6) to destination (6LBR). For example,
	example, 6LR_1 (i=1) is the router that receives the packets from the		6LR_1 (i=1) is the router that receives the packets from the IPv6
	IPv6 node.		node.
	In this case the RPI is added by the first 6LR (6LR1) (Node E),		In this case the RPI is added by the first 6LR (6LR1) (Node E),
	encapsulated in an IPv6-in-IPv6 header, and is modified in the		encapsulated in an IPv6-in-IPv6 header, and is modified in the
	following 6LRs. The RPI and entire packet is consumed by the root.		following 6LRs. The RPI and entire packet is consumed by the root.
	+---------+-----+----------------+----------------+-----------------+		The Figure 16 shows the table that summarizes what headers are needed
	| Header | IPv | 6LR_1 | 6LR_i | 6LBR |		for this use case.
	| | 6 | | | |
	+---------+-----+----------------+----------------+-----------------+
	| Inserte | -- | IPv6-in- | -- | -- |
	| d | | IPv6(RPI) | | |
	| headers | | | | |
	| Removed | -- | -- | -- | IPv6-in- |
	| headers | | | | IPv6(RPI) |
	| Re- | -- | -- | -- | -- |
	| added | | | | |
	| headers | | | | |
	| Modifie | -- | -- | IPv6-in- | -- |
	| d | | | IPv6(RPI) | |
	| headers | | | | |
	| Untouch | -- | -- | -- | -- |
	| ed | | | | |
	| headers | | | | |
	+---------+-----+----------------+----------------+-----------------+
	Table 16: Non Storing: Summary of the use of headers from not-RPL-		+----------+------+-------------------+------------------+-----------------+
			| Header | IPv6 | 6LR_1 | 6LR_i | 6LBR dst |
			| | src | | | |
			| | node | | | |
			+----------+------+-------------------+------------------+-----------------+
			| Inserted | -- | IPv6-in-IPv6(RPI) | -- | -- |
			| headers | | | | |
			+----------+------+-------------------+------------------+-----------------+
			| Removed | -- | -- | -- |IPv6-in-IPv6(RPI)|
			| headers | | | | |
			+----------+------+-------------------+------------------+-----------------+
			| Re-added | -- | -- | -- | -- |
			| headers | | | | |
			+----------+------+-------------------+------------------+-----------------+
			| Modified | -- | -- | IPv6-in-IPv6(RPI)| -- |
			| headers | | | | |
			+----------+------+-------------------+------------------+-----------------+
			|Untouched | -- | -- | -- | -- |
			| headers | | | | |
			+----------+------+-------------------+------------------+-----------------+
			Figure 16: Non Storing: Summary of the use of headers from not-RPL-
	aware-leaf to root		aware-leaf to root
	7.2. Non-Storing Mode: Interaction between Leaf and Internet		7.2. Non-Storing Mode: Interaction between Leaf and Internet
	This section will describe the communication flow in Non Storing Mode		This section will describe the communication flow in Non Storing Mode
	(Non-SM) between:		(Non-SM) between:
	RPL-aware-leaf to Internet		RPL-aware-leaf to Internet
	Internet to RPL-aware-leaf		Internet to RPL-aware-leaf
	skipping to change at page 34, line 49 ¶		skipping to change at page 36, line 4 ¶
	Internet to not-RPL-aware-leaf		Internet to not-RPL-aware-leaf
	7.2.1. Non-SM: Example of Flow from RPL-aware-leaf to Internet		7.2.1. Non-SM: Example of Flow from RPL-aware-leaf to Internet
	In this case the flow comprises:		In this case the flow comprises:
	RPL-aware-leaf (6LN) --> 6LR_i --> root (6LBR) --> Internet		RPL-aware-leaf (6LN) --> 6LR_i --> root (6LBR) --> Internet
	For example, a communication flow could be: Node F --> Node D -->		For example, a communication flow could be: Node F --> Node D -->
	Node B --> Node A --> Internet		Node B --> Node A --> Internet
			6LR_i is the intermediate router from source to destination. In this
	6LR_i are the intermediate routers from source to destination. In		case, "1 <= i <= n", n is the number of routers (6LR) that the packet
	this case, "1 <= i <= n", n is the number of routers (6LR) that the		goes through from source (6LN) to 6LBR.
	packet go through from source (6LN) to 6LBR.
	This case is identical to storing-mode case.		This case is identical to storing-mode case.
	The IPv6 flow label should be set to zero to aid in compression, and		The IPv6 flow label should be set to zero to aid in compression, and
	the 6LBR will set it to a non-zero value when sending towards the		the 6LBR will set it to a non-zero value when sending towards the
	Internet.		Internet.
	+-------------------+------+-------+------+----------------+		The Table 9 summarizes what headers are needed for this use case.
	| Header | 6LN | 6LR_i | 6LBR | Internet |
	+-------------------+------+-------+------+----------------+
	| Inserted headers | RPI | -- | -- | -- |
	| Removed headers | -- | -- | -- | -- |
	| Re-added headers | -- | -- | -- | -- |
	| Modified headers | -- | RPI | -- | -- |
	| Untouched headers | -- | -- | RPI | RPI (Ignored) |
	+-------------------+------+-------+------+----------------+
	Table 17: Non Storing: Summary of the use of headers from RPL-aware-		+-------------------+---------+-------+------+----------------+
			| Header | 6LN src | 6LR_i | 6LBR | Internet dst |
			+-------------------+---------+-------+------+----------------+
			| Inserted headers | RPI | -- | -- | -- |
			| Removed headers | -- | -- | -- | -- |
			| Re-added headers | -- | -- | -- | -- |
			| Modified headers | -- | RPI | -- | -- |
			| Untouched headers | -- | -- | RPI | RPI (Ignored) |
			+-------------------+---------+-------+------+----------------+
			Table 9: Non Storing: Summary of the use of headers from RPL-aware-
	leaf to Internet		leaf to Internet
	7.2.2. Non-SM: Example of Flow from Internet to RPL-aware-leaf		7.2.2. Non-SM: Example of Flow from Internet to RPL-aware-leaf
	In this case the flow comprises:		In this case the flow comprises:
	Internet --> root (6LBR) --> 6LR_i --> RPL-aware-leaf (6LN)		Internet --> root (6LBR) --> 6LR_i --> RPL-aware-leaf (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 is the intermediate router from source to destination. In this
	this case, "1 <= i <= n", n is the number of routers (6LR) that the		case, "1 <= i <= n", n is the number of routers (6LR) that the packet
	packet go through from 6LBR to destination(6LN).		goes through from 6LBR to destination(6LN).
	The 6LBR must add an RH3 header. As the 6LBR will know the path and		The 6LBR must add an RH3 header. As the 6LBR will know the path and
	address of the target node, it can address the IPv6-in-IPv6 header to		address of the target node, it can address the IPv6-in-IPv6 header to
	that node. The 6LBR will zero the flow label upon entry in order to		that node. The 6LBR will zero the flow label upon entry in order to
	aid compression.		aid compression.
			The Table 10 summarizes what headers are needed for this use case.
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	| Header | Internet | 6LBR | 6LR_i | 6LN |		| Header | Internet | 6LBR | 6LR_i | 6LN src |
			| | dst | | | |
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	| Inserted | -- | IPv6-in-IPv6 | -- | -- |		| Inserted | -- | IPv6-in-IPv6 | -- | -- |
	| headers | | (RH3,RPI) | | |		| headers | | (RH3,RPI) | | |
	| Removed | -- | -- | -- | IPv6-in-IPv6 |		| Removed | -- | -- | -- | IPv6-in-IPv6 |
	| headers | | | | (RH3,RPI) |		| headers | | | | (RH3,RPI) |
	| Re-added | -- | -- | -- | -- |		| Re-added | -- | -- | -- | -- |
	| headers | | | | |		| headers | | | | |
	| Modified | -- | -- | IPv6-in-IPv6 | -- |		| Modified | -- | -- | IPv6-in-IPv6 | -- |
	| headers | | | (RH3,RPI) | |		| headers | | | (RH3,RPI) | |
	| Untouched | -- | -- | -- | -- |		| Untouched | -- | -- | -- | -- |
	| headers | | | | |		| headers | | | | |
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	Table 18: Non Storing: Summary of the use of headers from Internet to		Table 10: Non Storing: Summary of the use of headers from Internet to
	RPL-aware-leaf		RPL-aware-leaf
	7.2.3. Non-SM: Example of Flow from not-RPL-aware-leaf to Internet		7.2.3. Non-SM: Example of Flow from not-RPL-aware-leaf to Internet
	In this case the flow comprises:		In this case the flow comprises:
	not-RPL-aware-leaf (IPv6) --> 6LR_1 --> 6LR_i -->root (6LBR) -->		not-RPL-aware-leaf (IPv6) --> 6LR_1 --> 6LR_i -->root (6LBR) -->
	Internet		Internet
	For example, a communication flow could be: Node G --> Node E -->		For example, a communication flow could be: Node G --> Node E -->
	Node B --> Node A --> Internet		Node B --> Node A --> Internet
	6LR_i are the intermediate routers from source to destination. In		6LR_i is the intermediate router from source to destination. In this
	this case, "1 < i <= n", n is the number of routers (6LR) that the		case, "1 < i <= n", n is the number of routers (6LR) that the packet
	packet go through from source(IPv6) to 6LBR. e.g 6LR_1 (i=1).		goes through from source(IPv6) to 6LBR. e.g 6LR_1 (i=1).
	In this case the flow label is recommended to be zero in the IPv6		In this case the flow label is recommended to be zero in the IPv6
	node. As RPL headers are added in the IPv6 node packet, the first		node. As RPL headers are added in the IPv6 node packet, the first
	6LR (6LR_1) will add a RPI header inside a new IPv6-in-IPv6 header.		6LR (6LR_1) will add a RPI header inside a new IPv6-in-IPv6 header.
	The IPv6-in-IPv6 header will be addressed to the root. This case is		The IPv6-in-IPv6 header will be addressed to the root. This case is
	identical to the storing-mode case (see Section 6.2.3).		identical to the storing-mode case (see Section 6.2.3).
	+---------+-----+------------+-------------+-------------+----------+		The Figure 17 shows the table that summarizes what headers are needed
	| Header | IPv | 6LR_1 | 6LR_i | 6LBR | Internet |		for this use case. In the figure, IP6-IP6 refers to IPv6-in-IPv6.
	| | 6 | | [i=2,..,n]_ | | |
	+---------+-----+------------+-------------+-------------+----------+
	| Inserte | -- | IPv6-in- | -- | -- | -- |
	| d | | IPv6 (RPI) | | | |
	| headers | | | | | |
	| Removed | -- | -- | -- | IPv6-in- | -- |
	| headers | | | | IPv6 (RPI) | |
	| Re- | -- | -- | -- | -- | -- |
	| added | | | | | |
	| headers | | | | | |
	| Modifie | -- | -- | IPv6-in- | -- | -- |
	| d | | | IPv6 (RPI) | | |
	| headers | | | | | |
	| Untouch | -- | -- | -- | -- | -- |
	| ed | | | | | |
	| headers | | | | | |
	+---------+-----+------------+-------------+-------------+----------+
	Table 19: Non Storing: Summary of the use of headers from not-RPL-		+-----------+------+--------------+--------------+--------------+----------+
			| Header | IPv6 | 6LR_1 | 6LR_i | 6LBR | Internet |
			| | src | | [i=2,..,n] | | dst |
			| | node | | | | |
			+-----------+------+--------------+--------------+--------------+----------+
			| Inserted | -- | IP6-IP6(RPI) | -- | -- | -- |
			| headers | | | | | |
			+-----------+------+--------------+--------------+--------------+----------+
			| Removed | -- | -- | -- | IP6-IP6(RPI) | -- |
			| headers | | | | | |
			+-----------+------+--------------+--------------+--------------+----------+
			| Re-added | -- | -- | -- | -- | -- |
			| headers | | | | | |
			+-----------+------+--------------+--------------+--------------+----------+
			| Modified | -- | -- | IP6-IP6(RPI) | -- | -- |
			| headers | | | | | |
			+-----------+------+--------------+--------------+--------------+----------+
			| Untouched | -- | -- | -- | -- | -- |
			| headers | | | | | |
			+-----------+------+--------------+--------------+--------------+----------+
			Figure 17: Non Storing: Summary of the use of headers from not-RPL-
	aware-leaf to Internet		aware-leaf to Internet
	7.2.4. Non-SM: Example of Flow from Internet to not-RPL-aware-leaf		7.2.4. Non-SM: Example of Flow from Internet to not-RPL-aware-leaf
	In this case the flow comprises:		In this case the flow comprises:
	Internet --> root (6LBR) --> 6LR_i --> not-RPL-aware-leaf (IPv6)		Internet --> root (6LBR) --> 6LR_i --> not-RPL-aware-leaf (IPv6)
	For example, a communication flow could be: Internet --> Node A		For example, a communication flow could be: Internet --> Node A
	(root) --> Node B --> Node E --> Node G		(root) --> Node B --> Node E --> Node G
	6LR_i are the intermediate routers from source to destination. In		6LR_i is the intermediate router from source to destination. In this
	this case, "1 < i <= n", n is the number of routers (6LR) that the		case, "1 < i <= n", n is the number of routers (6LR) that the packet
	packet go through from 6LBR to not-RPL-aware-leaf (IPv6).		goes through from 6LBR to not-RPL-aware-leaf (IPv6).
	The 6LBR must add an RH3 header inside an IPv6-in-IPv6 header. The		The 6LBR must add an RH3 header inside an IPv6-in-IPv6 header. The
	6LBR will know the path, and will recognize that the final node is		6LBR will know the path, and will recognize that the final node is
	not an RPL capable node as it will have received the connectivity DAO		not an RPL capable node as it will have received the connectivity DAO
	from the nearest 6LR. The 6LBR can therefore make the IPv6-in-IPv6		from the nearest 6LR. The 6LBR can therefore make the IPv6-in-IPv6
	header destination be the last 6LR. The 6LBR will set to zero the		header destination be the last 6LR. The 6LBR will set to zero the
	flow label upon entry in order to aid compression.		flow label upon entry in order to aid compression.
	+---------+--------+------------+------------+---------------+------+		The Figure 18 shows the table that summarizes what headers are needed
	| Header | Intern | 6LBR | 6LR_1 | 6LR_i(i=2,.., | IPv6 |		for this use case.
	| | et | | | n) | |
	+---------+--------+------------+------------+---------------+------+
	| Inserte | -- | IPv6-in- | -- | -- | -- |
	| d | | IPv6 (RH3, | | | |
	| headers | | RPI) | | | |
	| Removed | -- | -- | -- | IPv6-in-IPv6 | -- |
	| headers | | | | (RH3,RPI)(1) | |
	| Re- | -- | -- | -- | -- | -- |
	| added | | | | | |
	| headers | | | | | |
	| Modifie | -- | -- | IPv6-in- | IPv6-in-IPv6 | -- |
	| d | | | IPv6 | (RH3, RPI) | |
	| headers | | | (RH3,RPI) | | |
	| Untouch | -- | -- | -- | -- | -- |
	| ed | | | | | |
	| headers | | | | | |
	+---------+--------+------------+------------+---------------+------+
	Table 20: NonStoring: Summary of the use of headers from Internet to		+-----------+--------+--------------+--------------+--------------+------+
	non-RPL-aware-leaf (1) The last 6LR before the IPv6 node.		| Header |Internet| 6LBR | 6LR_1 | 6lR_i | IPv6 |
			| | src | | | (i=2,...,n) | dst |
			| | | | | | node |
			+-----------+--------+--------------+--------------+--------------+------+
			| Inserted | -- | IPv6-in-IPv6 | -- | -- | -- |
			| headers | | (RH3,RPI) | | | |
			+-----------+--------+--------------+--------------+--------------+------+
			| Removed | -- | -- | -- | IPv6-in-IPv6 | -- |
			| headers | | | | (RH3,RPI)[1] | |
			+-----------+--------+--------------+--------------+--------------+------+
			| Re-added | -- | -- | -- | -- | -- |
			| headers | | | | | |
			+-----------+--------+--------------+--------------+--------------+------+
			| Modified | -- | -- | IPv6-in-IPv6 | IPv6-in-IPv6 | -- |
			| headers | | | (RH3,RPI) | (RH3,RPI) | |
			+-----------+--------+--------------+--------------+--------------+------+
			| Untouched | -- | -- | -- | -- | -- |
			| headers | | | | | |
			+-----------+--------+--------------+--------------+--------------+------+
			Figure 18: Non-Storing mode: Summary of the use of headers from
			Internet to not-RPL-aware-leaf [1] The last 6LR before the IPv6 node.
	7.3. Non-Storing Mode: Interaction between Leafs		7.3. Non-Storing Mode: Interaction between Leafs
	In this section is described the communication flow in Non Storing		In this section is described the communication flow in Non Storing
	Mode (Non-SM) between,		Mode (Non-SM) between,
	RPL-aware-leaf to RPL-aware-leaf		RPL-aware-leaf to RPL-aware-leaf
	RPL-aware-leaf to not-RPL-aware-leaf		RPL-aware-leaf to not-RPL-aware-leaf
	skipping to change at page 38, line 49 ¶		skipping to change at page 40, line 4 ¶
	not-RPL-aware-leaf to not-RPL-aware-leaf		not-RPL-aware-leaf to not-RPL-aware-leaf
	7.3.1. Non-SM: Example of Flow from RPL-aware-leaf to RPL-aware-leaf		7.3.1. Non-SM: Example of Flow from RPL-aware-leaf to RPL-aware-leaf
	In this case the flow comprises:		In this case the flow comprises:
	6LN src --> 6LR_ia --> root (6LBR) --> 6LR_id --> 6LN dst		6LN src --> 6LR_ia --> root (6LBR) --> 6LR_id --> 6LN dst
	For example, a communication flow could be: Node F --> Node D -->		For example, a communication flow could be: Node F --> Node D -->
	Node B --> Node A (root) --> Node B --> Node E --> Node H		Node B --> Node A (root) --> Node B --> Node E --> Node H
			6LR_ia is the intermediate router from source to the root In this
	6LR_ia are the intermediate routers from source to the root In this
	case, "1 <= ia <= n", n is the number of routers (6LR) that the		case, "1 <= ia <= n", n is the number of routers (6LR) that the
	packet go through from 6LN to the root.		packet goes through from 6LN to the root.
	6LR_id are the intermediate routers from the root to the destination.		6LR_id is the intermediate router 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 should put the RPI into an IPv6-in-IPv6 header		The originating node must put the RPI into an IPv6-in-IPv6 header
	addressed to the root, so that the 6LBR can remove that header. If		addressed to the root, so that the 6LBR can remove that header. If
	it does not, then additional resources are wasted on the way down to		it does not, then additional resources are wasted on the way down to
	carry the useless RPI option.		carry the useless RPI option.
	The 6LBR will need to insert an RH3 header, which requires that it		The 6LBR will need to insert an RH3 header, which requires that it
	add an IPv6-in-IPv6 header. It should be able to remove the RPI, as		add an IPv6-in-IPv6 header. It should be able to remove the RPI, as
	it was contained in an IPv6-in-IPv6 header addressed to it.		it was contained in an IPv6-in-IPv6 header addressed to it.
	Otherwise, there may be a RPI header buried inside the inner IP		Otherwise, there may be a RPI header buried inside the inner IP
	header, which should get ignored.		header, which should get ignored.
	Networks that use the RPL P2P extension [RFC6997] are essentially		Networks that use the RPL P2P extension [RFC6997] are essentially
	non-storing DODAGs and fall into this scenario or scenario		non-storing DODAGs and fall into this scenario or scenario
	Section 7.1.2, with the originating node acting as 6LBR.		Section 7.1.2, with the originating node acting as 6LBR.
	+---------+------------+-------+-------------+--------+-------------+		The Figure 19 shows the table that summarizes what headers are needed
	| Header | 6LN src | 6LR_i | 6LBR | 6LR_id | 6LN dst |		for this use case.
	| | | a | | | |
	+---------+------------+-------+-------------+--------+-------------+
	| Inserte | IPv6-in- | -- | IPv6-in- | -- | -- |
	| d | IPv6 | | IPv6 | | |
	| headers | (RPI1) | | (RH3->6LN, | | |
	| | | | opt RPI2) | | |
	| Removed | -- | -- | IPv6-in- | -- | IPv6-in- |
	| headers | | | IPv6 (RPI1) | | IPv6 (RH3, |
	| | | | | | opt RPI2) |
	| Re- | -- | -- | -- | -- | -- |
	| added | | | | | |
	| headers | | | | | |
	| Modifie | -- | RPI1 | -- | RPI2 | -- |
	| d | | | | | |
	| headers | | | | | |
	| Untouch | -- | -- | -- | -- | -- |
	| ed | | | | | |
	| headers | | | | | |
	+---------+------------+-------+-------------+--------+-------------+
	Table 21: Non Storing: Summary of the use of headers for RPL-aware-		+---------+------------+------------+------------+------------+------------+
	leaf to RPL-aware-leaf		| Header | 6LN | 6LR_ia | 6LBR | 6LR_id | 6LN |
			| | src | | | | dst |
			+---------+------------+------------+------------+------------+------------+
			| Inserted|IPv6-in-IPv6| |IPv6-in-IPv6| -- | -- |
			| headers | (RPI1) | |(RH3-> 6LN, | | |
			| | | | RPI2) | | |
			+---------+------------+------------+------------+------------+------------+
			| Removed | -- | -- |IPv6-in-IPv6| -- |IPv6-in-IPv6|
			| headers | | | (RPI1) | | (RH3, |
			| | | | | | RPI2) |
			+---------+------------+------------+------------+------------+------------+
			| Re-added| -- | -- | -- | -- | -- |
			| headers | | | | | |
			+---------+------------+------------+------------+------------+------------+
			| Modified| -- |IPv6-in-IPv | -- |IPv6-in-IPv6| -- |
			| headers | | (RPI1) | | (RPI2) | |
			+---------+------------+------------+------------+------------+------------+
			|Untouched| -- | -- | -- | -- | -- |
			| headers | | | | | |
			+---------+------------+------------+------------+------------+------------+
			Figure 19: Non Storing mode: Summary of the use of headers for RPL-
			aware-leaf to RPL-aware-leaf
	7.3.2. Non-SM: Example of Flow from RPL-aware-leaf to not-RPL-aware-		7.3.2. Non-SM: Example of Flow from RPL-aware-leaf to not-RPL-aware-
	leaf		leaf
	In this case the flow comprises:		In this case the flow comprises:
	6LN --> 6LR_ia --> root (6LBR) --> 6LR_id --> not-RPL-aware (IPv6)		6LN --> 6LR_ia --> root (6LBR) --> 6LR_id --> not-RPL-aware (IPv6)
	For example, a communication flow could be: Node F --> Node D -->		For example, a communication flow could be: Node F --> Node D -->
	Node B --> Node A (root) --> Node B --> Node E --> Node G		Node B --> Node A (root) --> Node B --> Node E --> Node G
	6LR_ia are the intermediate routers from source to the root In this		6LR_ia is the intermediate router 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 is the intermediate router 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 (6LRs).
	As in the previous case, the 6LN will insert a RPI (RPI_1) header		As in the previous case, the 6LN will insert a RPI (RPI_1) header
	which must be in an IPv6-in-IPv6 header addressed to the root so that		which must be in an IPv6-in-IPv6 header addressed to the root so that
	the 6LBR can remove this RPI. The 6LBR will then insert an RH3		the 6LBR can remove this RPI. The 6LBR will then insert an RH3
	inside a new IPv6-in-IPv6 header addressed to the 6LR_id. The RPI is		inside a new IPv6-in-IPv6 header addressed to the 6LR_id.
	optional from 6LBR to 6LR_id (RPI_2).
	+---------+-----------+-----------+------------+------------+-------+		The Figure 20 shows the table that summarizes what headers are needed
	| Header | 6LN | 6LR_1 | 6LBR | 6LR_id | IPv6 |		for this use case. In the figure, IP6-IP6 refers to IPv6-in-IPv6.
	+---------+-----------+-----------+------------+------------+-------+
	| Inserte | IPv6-in- | -- | IPv6-in- | -- | -- |
	| d | IPv6 | | IPv6 (RH3, | | |
	| headers | (RPI1) | | opt RPI_2) | | |
	| Removed | -- | -- | IPv6-in- | IPv6-in- | -- |
	| headers | | | IPv6 | IPv6 (RH3, | |
	| | | | (RPI_1) | opt RPI_2) | |
	| Re- | -- | -- | -- | -- | -- |
	| added | | | | | |
	| headers | | | | | |
	| Modifie | -- | IPv6-in- | -- | IPv6-in- | -- |
	| d | | IPv6 | | IPv6 (RH3, | |
	| headers | | (RPI_1) | | opt RPI_2) | |
	| Untouch | -- | -- | -- | -- | opt |
	| ed | | | | | RPI_2 |
	| headers | | | | | |
	+---------+-----------+-----------+------------+------------+-------+
	Table 22: Non Storing: Summary of the use of headers from RPL-aware-		+-----------+---------+---------+---------+---------+---------+------+
	leaf to not-RPL-aware-leaf		| Header | 6LN | 6LR_ia | 6LBR | 6LR_id | 6LR_m | IPv6 |
			| | src | | | | | dst |
			| | | | | | | node |
			+-----------+---------+---------+---------+---------+---------+------+
			| Inserted | IP6-IP6 | | IP6-IP6 | -- | -- | -- |
			| headers | (RPI1) | | (RH3, | | | |
			| | | | RPI2) | | | |
			+-----------+---------+---------+---------+---------+---------+------+
			| Removed | -- | -- | IP6-IP6 | -- | IP6-IP6 | -- |
			| headers | | | (RPI1) | | (RH3, | |
			| | | | | | RPI2) | |
			+-----------+---------+---------+---------+---------+---------+------+
			| Re-added | -- | -- | -- | -- | -- | -- |
			| headers | | | | | | |
			+-----------+---------+---------+---------+---------+---------+------+
			| Modified | -- | IP6-IP6 | -- | IP6-IP6 | | -- |
			| headers | | (RPI1) | | (RH3, | | |
			| | | | | RPI2) | | |
			+-----------+---------+---------+---------+---------+---------+------+
			| Untouched | -- | -- | -- | -- | -- | -- |
			| headers | | | | | | |
			+-----------+---------+---------+---------+---------+---------+------+
			Figure 20: Non Storing: Summary of the use of headers from RPL-aware-
			leaf to not-RPL-aware-leaf.
	7.3.3. Non-SM: Example of Flow from not-RPL-aware-leaf to RPL-aware-		7.3.3. Non-SM: Example of Flow from not-RPL-aware-leaf to RPL-aware-
	leaf		leaf
	In this case the flow comprises:		In this case the flow comprises:
	not-RPL-aware 6LN (IPv6) --> 6LR_ia --> root (6LBR) --> 6LR_id -->		not-RPL-aware 6LN (IPv6) --> 6LR_1 --> 6LR_ia --> root (6LBR) -->
	6LN		6LR_id --> 6LN
	For example, a communication flow could be: Node G --> Node E -->		For example, a communication flow could be: Node G --> Node E -->
	Node B --> Node A (root) --> Node B --> Node E --> Node H		Node B --> Node A (root) --> Node B --> Node E --> Node H
	6LR_ia are the intermediate routers from source to the root. In this		6LR_ia is the intermediate router 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 is the intermediate router from the root to the destination.
	In this case, "1 <= ia <= m", m is the number of the intermediate		In this case, "1 <= ia <= m", m is the number of the intermediate
	routers (6LR).		routers (6LR).
	This scenario is mostly identical to the previous one. The RPI is		This scenario is mostly identical to the previous one. The RPI is
	added by the first 6LR (6LR_1) inside an IPv6-in-IPv6 header		added by the first 6LR (6LR_1) inside an IPv6-in-IPv6 header
	addressed to the root. The 6LBR will remove this RPI, and add it's		addressed to the root. The 6LBR will remove this RPI, and add it's
	own IPv6-in-IPv6 header containing an RH3 header and optional RPI		own IPv6-in-IPv6 header containing an RH3 header and an RPI (RPI_2).
	(RPI_2).
	+---------+-----+------------+------------+------------+------------+		The Figure 21 shows the table that summarizes what headers are needed
	| Header | IPv | 6LR_1 | 6LBR | 6LR_id | 6LN |		for this use case. In the figure, IP6-IP6 refers to IPv6-in-IPv6.
	| | 6 | | | | |
	+---------+-----+------------+------------+------------+------------+
	| Inserte | -- | IPv6-in- | IPv6-in- | -- | -- |
	| d | | IPv6 | IPv6 (RH3, | | |
	| headers | | (RPI_1) | opt RPI_2) | | |
	| Removed | -- | -- | IPv6-in- | -- | IPv6-in- |
	| headers | | | IPv6 | | IPv6 (RH3, |
	| | | | (RPI_1) | | opt RPI_2) |
	| Re- | -- | -- | -- | -- | -- |
	| added | | | | | |
	| headers | | | | | |
	| Modifie | -- | -- | -- | IPv6-in- | -- |
	| d | | | | IPv6 (RH3, | |
	| headers | | | | opt RPI_2) | |
	| Untouch | -- | -- | -- | -- | -- |
	| ed | | | | | |
	| headers | | | | | |
	+---------+-----+------------+------------+------------+------------+
	Table 23: Non Storing: Summary of the use of headers from not-RPL-		+-----------+------+---------+---------+---------+---------+---------+
	aware-leaf to RPL-aware-leaf		| Header | IPv6 | 6LR_1 | 6LR_ia | 6LBR | 6LR_id | 6LN |
			| | src | | | | | dst |
			| | node | | | | | |
			+-----------+------+---------+---------+---------+---------+---------+
			| Inserted | -- | IP6-IP6 | -- | IP6-IP6 | -- | -- |
			| headers | | (RPI1) | | (RH3, | | |
			| | | | | RPI2) | | |
			+-----------+------+---------+---------+---------+---------+---------+
			| Removed | -- | | -- | IP6-IP6 | -- | IP6-IP6 |
			| headers | | | | (RPI1) | | (RH3, |
			| | | | | | | RPI2) |
			+-----------+------+---------+---------+---------+---------+---------+
			| Re-added | -- | | -- | -- | -- | -- |
			| headers | | | | | | |
			+-----------+------+---------+---------+---------+---------+---------+
			| Modified | -- | | IP6-IP6 | -- | IP6-IP6 | -- |
			| headers | | | (RPI1) | | (RH3, | |
			| | | | | | RPI2) | |
			+-----------+------+---------+---------+---------+---------+---------+
			| Untouched | -- | | -- | -- | -- | -- |
			| headers | | | | | | |
			+-----------+------+---------+---------+---------+---------+---------+
			Figure 21: Non Storing: Summary of the use of headers from not-RPL-
			aware-leaf to RPL-aware-leaf.
	7.3.4. Non-SM: Example of Flow from not-RPL-aware-leaf to not-RPL-		7.3.4. Non-SM: Example of Flow from not-RPL-aware-leaf to not-RPL-
	aware-leaf		aware-leaf
	In this case the flow comprises:		In this case the flow comprises:
	not-RPL-aware 6LN (IPv6 src)--> 6LR_ia --> root (6LBR) --> 6LR_id -->		not-RPL-aware 6LN (IPv6 src) --> 6LR_1 --> 6LR_ia --> root (6LBR) -->
	not-RPL-aware (IPv6 dst)		6LR_id --> not-RPL-aware (IPv6 dst)
	For example, a communication flow could be: Node G --> Node E -->		For example, a communication flow could be: Node G --> Node E -->
	Node B --> Node A (root) --> Node C --> Node J		Node B --> Node A (root) --> Node C --> Node J
	6LR_ia are the intermediate routers from source to the root. In this		6LR_ia is the intermediate router from source to the root. In this
	case, "1 <= ia <= n", n is the number of intermediate routers (6LR)		case, "1 <= ia <= n", n is the number of intermediate routers (6LR)
			6LR_id is the intermediate router from the root to the destination.
	6LR_id are the intermediate routers from the root to the destination.
	In this case, "1 <= ia <= m", m is the number of the intermediate		In this case, "1 <= ia <= m", m is the number of the intermediate
	routers (6LR).		routers (6LR).
	This scenario is the combination of the previous two cases.		This scenario is the combination of the previous two cases.
	+----------+-----+-------------+--------------+--------------+------+		The Figure 22 shows the table that summarizes what headers are needed
	| Header | IPv | 6LR_1 | 6LBR | 6LR_id | IPv6 |		for this use case. In the figure, IP6-IP6 refers to IPv6-in-IPv6.
	| | 6 | | | | dst |
	| | src | | | | |
	+----------+-----+-------------+--------------+--------------+------+
	| Inserted | -- | IPv6-in- | IPv6-in-IPv6 | -- | -- |
	| headers | | IPv6 | (RH3, opt | | |
	| | | (RPI_1) | RPI_2) | | |
	| Removed | -- | -- | IPv6-in-IPv6 | IPv6-in-IPv6 | -- |
	| headers | | | (RPI_1) | (RH3, opt | |
	| | | | | RPI_2) | |
	| Re-added | -- | -- | -- | -- | -- |
	| headers | | | | | |
	| Modified | -- | -- | -- | -- | -- |
	| headers | | | | | |
	| Untouche | -- | -- | -- | -- | -- |
	| d | | | | | |
	| headers | | | | | |
	+----------+-----+-------------+--------------+--------------+------+
	Table 24: Non Storing: Summary of the use of headers from not-RPL-		+---------+------+-------+-------+---------+-------+---------+------+
			| Header | IPv6 | 6LR_1 | 6LR_ia| 6LBR |6LR_id | 6LR_m | IPv6 |
			| | src | | | | | | dst |
			| | node | | | | | | node |
			+---------+------+-------+-------+---------+-------+---------+------+
			| Inserted| -- |IP6-IP6| -- | IP6-IP6 | -- | -- | -- |
			| headers | | (RPI1)| | (RH3, | | | |
			| | | | | RPI2) | | | |
			+---------+------+-------+-------+---------+-------+---------+------+
			| Removed | -- | -- | -- | IP6-IP6 | -- | IP6-IP6 | -- |
			| headers | | | | (RPI1) | | (RH3, | |
			| | | | | | | RPI2) | |
			+---------+------+-------+-------+---------+-------+---------+------+
			| Re-added| -- | -- | -- | -- | -- | -- | -- |
			| headers | | | | | | | |
			+---------+------+-------+-------+---------+-------+---------+------+
			| Modified| -- | -- |IP6-IP6| -- |IP6-IP6| -- | -- |
			| headers | | | (RPI1)| | (RH3, | | |
			| | | | | | RPI2)| | |
			+---------+------+-------+-------+---------+-------+---------+------+
			|Untouched| -- | -- | -- | -- | -- | -- | -- |
			| headers | | | | | | | |
			+---------+------+-------+-------+---------+-------+---------+------+
			Figure 22: Non Storing: Summary of the use of headers from not-RPL-
	aware-leaf to not-RPL-aware-leaf		aware-leaf to not-RPL-aware-leaf
	8. Operational Considerations of supporting not-RPL-aware-leaves		8. Operational Considerations of supporting not-RPL-aware-leaves
	Roughly half of the situations described in this document involve		Roughly half of the situations described in this document involve
	leaf ("host") nodes that do not speak RPL. These nodes fall into two		leaf ("host") nodes that do not speak RPL. These nodes fall into two
	further categories: ones that drop a packet that have RPI or RH3		further categories: ones that drop a packet that have RPI or RH3
	headers, and ones that continue to process a packet that has RPI and/		headers, and ones that continue to process a packet that has RPI and/
	or RH3 headers.		or RH3 headers.
	skipping to change at page 43, line 27 ¶		skipping to change at page 45, line 20 ¶
	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.
	The above case occurs whenever traffic originates from the outside		The above case occurs whenever traffic originates from the outside
	the LLN (the "Internet" cases above), and non-storing mode is used.		the LLN (the "Internet" cases above), and non-storing mode is used.
	In non-storing mode, the RPL root knows the exact topology (as it		In non-storing mode, the RPL root knows the exact topology (as it
	must be create the RH3 header), and therefore knows what the 6LR		must be create the RH3 header), and therefore knows what the 6LR
	prior to the leaf --- the 6LR_n.		prior to the leaf. For example, in Figure 5, node E is the 6LR prior
			to the leaf node G, or node C is the 6LR prior to the leaf node J.
	Traffic originating from the RPL root (such as when the data		Traffic originating from the RPL root (such as when the data
	collection system is co-located on the RPL root), does not require an		collection system is co-located on the RPL root), does not require an
	IPv6-in-IPv6 header (in either mode), as the packet is originating at		IPv6-in-IPv6 header (in either mode), as the packet is originating at
	the root, and the root can insert the RPI and RH3 headers directly		the root, and the root can insert the RPI and RH3 headers directly
	into the packet, as it is formed. Such a packet is slightly smaller,		into the packet, as it is formed. Such a packet is slightly smaller,
	but only can be sent to nodes (whether RPL aware or not), that will		but only can be sent to nodes (whether RPL aware or not), that will
	tolerate the RPL artifacts.		tolerate the RPL artifacts.
	An operator that finds itself with a lot of traffic from the RPL root		An operator that finds itself with a lot of traffic from the RPL root
	skipping to change at page 44, line 5 ¶		skipping to change at page 45, line 46 ¶
	As storing mode can not know the final path of the traffic,		As storing mode can not know the final path of the traffic,
	intolerant (that drop packets with RPL artifacts) leaf nodes can not		intolerant (that drop packets with RPL artifacts) leaf nodes can not
	be supported.		be supported.
	9. Operational considerations of introducing 0x23		9. Operational considerations of introducing 0x23
	This section describes the operational considerations of introducing		This section describes the operational considerations of introducing
	the new RPI value of 0x23.		the new RPI value of 0x23.
	Related to the deployment of RPL, there are no known multivendor		During bootstrapping the node gets the DIO with the information of
	deployments outside of the research groups! All known deployments of		RPL Option Type, indicating the new RPI in the DODAG Configuration
	RPL are in market verticals, with a single vendor providing all		Option Flag. The DODAG root is in charge to configure the current
	components. Research groups typically are using Contiki, RiotOS, or		network to the new value, through DIO messages and when all the nodes
	OpenWSN, and these are easily adapted to 0x23 functionality.		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
			Option Type. Thus, the DIO is sent with a flag indicating the new
			RPI value.
	During bootstrapping the node get the DIO with the information of RPL		The DODAG Configuration option is contained in a RPL DIO message,
	Option Type, indicating the new RPI in the DODAG Configuration Option		which contains a unique DTSN counter. The leaf nodes respond to this
	Flag. The DODAG root is in charge to configure the current network		message with DAO messages containing the same DTSN. This is a normal
	to the new value, through DIO messages and when all the nodes are set		part of RPL routing; the RPL root therefore knows when the updated
	with the new value. The DODAG should change to a new DODAG version.		DODAG Configuration Option has been seen by all nodes.
	In case of rebooting, the node does not remember the RPL Option Type.
	Thus, the DIO is sent with a flag indicating the new RPI value.
	The migration path to the change from 0x63 to 0x23 in networks that		Before the migration happens, all the RPL-aware nodes should support
	accepts both values is changed when the DIO is sent with the flag		both values . The migration procedure it is triggered when the DIO
	indicating the new RPI value. Namely, it remains at 0x63 until it is		is sent with the flag indicating the new RPI value. Namely, it
	sure that the network is capable of 0x23, then it abruptly change to		remains at 0x63 until it is sure that the network is capable of 0x23,
	0x23. This options allows to send packets to non-RPL nodes, which		then it abruptly change to 0x23. This options allows to send packets
	should ignore the option and continue processing the packets.		to not-RPL nodes, which should ignore the option and continue
			processing the packets.
	In case that a node join to a network that only process 0x63, it		In case that a node join to a network that only process 0x63, it
	would produce a flag day as was mentioned previously. Indicating the		would produce a flag day as was mentioned previously. Indicating the
	new RPI in the DODAG Configuration Option Flag is a way to avoid the		new RPI in the DODAG Configuration Option Flag is a way to avoid the
	flag day in a network. It is recommended that a network process both		flag day in a network. It is recommended that a network process both
	options to enable interoperability.		options to enable interoperability.
	10. IANA Considerations		10. IANA Considerations
	This document updates the registration made in [RFC6553] Destination		This document updates the registration made in [RFC6553] Destination
	Options and Hop-by-Hop Options registry from 0x63 to 0x23.		Options and Hop-by-Hop Options registry from 0x63 to 0x23 as shown in
			Figure 23.
	[RFCXXXX] represents this document.		[RFCXXXX] represents this document.
	Hex Value Binary Value		Hex Value Binary Value
	act chg rest Description Reference		act chg rest Description Reference
	--------- --- --- ------- ----------------- ----------		--------- --- --- ------- ----------------- ----------
	0x23 00 1 00011 RPL Option [RFCXXXX]		0x23 00 1 00011 RPL Option [RFCXXXX]
	0x63 01 1 00011 RPL Option(DEPRECATED) [RFC6553][RFCXXXX]		0x63 01 1 00011 RPL Option(DEPRECATED) [RFC6553][RFCXXXX]
	Figure 9: Option Type in RPL Option.		Figure 23: Option Type in RPL Option.
	The DODAG Configuration Option Flags in the DODAG Configuration		DODAG Configuration option is updated as follows (Figure 24):
	option is updated as follows:
	+------------+-----------------+---------------+		+------------+-----------------+---------------+
	| Bit number | Description | Reference |		| Bit number | Description | Reference |
	+------------+-----------------+---------------+		+------------+-----------------+---------------+
	| 3 | RPI 0x23 enable | This document |		| 3 | RPI 0x23 enable | This document |
	+------------+-----------------+---------------+		+------------+-----------------+---------------+
	Figure 10: DODAG Configuration Option Flag to indicate the RPI-flag-		Figure 24: DODAG Configuration Option Flag to indicate the RPI-flag-
	day.		day.
	11. Security Considerations		11. Security Considerations
	The security considerations covered in [RFC6553] and [RFC6554] apply		The security considerations covered in [RFC6553] and [RFC6554] apply
	when the packets are in the RPL Domain.		when the packets are in the RPL Domain.
	The IPv6-in-IPv6 mechanism described in this document is much more		The IPv6-in-IPv6 mechanism described in this document is much more
	limited than the general mechanism described in [RFC2473]. The		limited than the general mechanism described in [RFC2473]. The
	willingness of each node in the LLN to decapsulate packets and		willingness of each node in the LLN to decapsulate packets and
	forward them could be exploited by nodes to disguise the origin of an		forward them could be exploited by nodes to disguise the origin of an
	attack.		attack.
	While a typical LLN may be a very poor origin for attack traffic (as		While a typical LLN may be a very poor origin for attack traffic (as
	the networks tend to be very slow, and the nodes often have very low		the networks tend to be very slow, and the nodes often have very low
	duty cycles) given enough nodes, they could still have a significant		duty cycles) given enough nodes, they could still have a significant
	impact, particularly if the attack was on another LLN! Additionally,		impact, particularly if the target of the attack is targeting another
	some uses of RPL involve large backbone ISP scale equipment		LLN. Additionally, some uses of RPL involve large backbone ISP scale
	[I-D.ietf-anima-autonomic-control-plane], which may be equipped with		equipment [I-D.ietf-anima-autonomic-control-plane], which may be
	multiple 100Gb/s interfaces.		equipped with multiple 100Gb/s interfaces.
	Blocking or careful filtering of IPv6-in-IPv6 traffic entering the		Blocking or careful filtering of IPv6-in-IPv6 traffic entering the
	LLN as described above will make sure that any attack that is mounted		LLN as described above will make sure that any attack that is mounted
	must originate from compromised nodes within the LLN. The use of		must originate from compromised nodes within the LLN. The use of
	BCP38 filtering at the RPL root on egress traffic will both alert the		BCP38 [BCP38] filtering at the RPL root on egress traffic will both
	operator to the existence of the attack, as well as drop the attack		alert the operator to the existence of the attack, as well as drop
	traffic. As the RPL network is typically numbered from a single		the attack traffic. As the RPL network is typically numbered from a
	prefix, which is itself assigned by RPL, BCP38 filtering involves a		single prefix, which is itself assigned by RPL, BCP38 filtering
	single prefix comparison and should be trivial to automatically		involves a single prefix comparison and should be trivial to
	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 [I-D.ietf-anima-bootstrapping-keyinfra]
	and [I-D.ietf-6tisch-dtsecurity-secure-join]. This is the case for		and [I-D.ietf-6tisch-dtsecurity-secure-join]. This is the case for
	the RPL root to do careful filtering: it occurs only when the Join		the 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.
	With the above precautions, an attack using IPv6-in-IPv6 tunnels will		With the above precautions, an attack using IPv6-in-IPv6 tunnels can
	be by a node within the LLN on another node within the LLN. Such an		only be by a node within the LLN on another node within the LLN.
	attack could, of course, be done directly. An attack of this kind is		Such an attack could, of course, be done directly. An attack of this
	meaningful only if the source addresses are either fake or if the		kind is meaningful only if the source addresses are either fake or if
	point is to amplify return traffic. Such an attack, could also be		the point is to amplify return traffic. Such an attack, could also
	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.
	[RFC2473] suggests that tunnel entry and exit points can be secured,		Whenever IPv6-in-IPv6 headers are being proposed, there is a concern
	via the "Use IPsec". The suggested solution has all the problems		about creating security issues. In the security section of
	that [RFC5406] goes into. In an LLN such a solution would degenerate		[RFC2473], it was suggested that tunnel entry and exit points can be
	into every node having a tunnel with every other node. It would		secured, via "Use IPsec". This recommendation is not practical for
	provide a small amount of origin address authentication at a very		RPL networks. [RFC5406] goes into some detail on what additional
	high cost; doing BCP38 at every node (linking layer-3 addresses to		details would be needed in order to "Use IPsec". Use of ESP would
	layer-2 addresses, and to already present layer-2 cryptographic		prevent RFC8183 compression (compression must occur before
	mechanisms) would be cheaper should RPL be run in an environment		encryption), and RFC8183 compression is lossy in a way that prevents
	where hostile nodes are likely to be a part of the LLN.		use of AH. These are minor issues. The major issue is how to
			establish trust enough such that IKEv2 could be used. This would
			require a system of certificates to be present in every single node,
			including any Internet nodes that might need to communicate with the
			LLN. Thus, "Use IPsec" requires a global PKI in the general case.
			More significantly, the use of IPsec tunnels to protect the IPv6-in-
			IPv6 headers would in the general case scale with the square of the
			number of nodes. This is a lot of resource for a constrained nodes
			on a constrained network. In the end, the IPsec tunnels would be
			providing only BCP38-like origin authentication! Just doing BCP38
			origin filtering at the entry and exit of the LLN provides a similar
			level amount of security without all the scaling and trust problems
			of using IPsec as RFC2473 suggested. IPsec is not recommended.
			An LLN with hostile nodes within it would not be protected against
			impersonation with the LLN by entry/exit filtering.
	The RH3 header usage described here can be abused in equivalent ways		The RH3 header usage described here can be abused in equivalent ways
	with an IPv6-in-IPv6 header to add the needed RH3 header. As such,		(to disguise the origin of traffic and attack other nodes) with an
	the attacker's RH3 header will not be seen by the network until it		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
	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
	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
	skipping to change at page 47, line 28 ¶		skipping to change at page 49, line 45 ¶
	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
	[I-D.ietf-6lo-ap-nd]. The attacker will not be able to source with		[I-D.ietf-6lo-ap-nd]. The attacker will not be able to source
	an address that is not registered, and the registration checks for		traffic with an address that is not registered, and the registration
	topological correctness. Notice that there is an L2 authentication		process checks for topological correctness. Notice that there is an
	in most of the cases. If an attack comes from outside LLN IPv6-in-		L2 authentication in most of the cases. If an attack comes from
	IPv6 can be used to hide inner routing headers, but RH3 is protected		outside LLN IPv6-in- IPv6 can be used to hide inner routing headers,
	by its definition.		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
			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 do a deep packet inspection wherein		simpler solution), or it SHOULD walk the IP header extension chain
	it walks the IP header extension chain until it can inspect the		until it can inspect the upper-layer-payload as described in
	upper-layer-payload as described in [RFC7045]. In particular, the		[RFC7045]. In particular, the RPL root SHOULD do [BCP38] processing
	RPL root SHOULD do BCP38 ([RFC2827]) processing on the source		on the source addresses of all IP headers that it examines in both
	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.
	12. Acknowledgments		12. Acknowledgments
	We are very thankful to the grant by the Finnish Foundation for		This work is done thanks to the grant by the Stand.ICT project.
	Technology Promotion (Tekniikan Edistaemissaeaetioen - TES), and the
	grant by the FP7 Marie Curie Initial Training Network (ITN) METRICS
	project (grant agreement No. 607728)
	A special BIG thanks to C. M. Heard for the help with the		A special BIG thanks to C. M. Heard for the help with the
	Section 3. Much of the redaction in that section is based on his		Section 3. Much of the redaction in that section is based on his
	comments.		comments.
	Additionally, the authors would like to acknowledge the review,		Additionally, the authors would like to acknowledge the review,
	feedback, and comments of (alphabetical order): Robert Cragie, Simon		feedback, and comments of (alphabetical order): Robert Cragie, Simon
	Duquennoy, Ralph Droms, Cenk Guendogan, Rahul Jadhav, Matthias		Duquennoy, Ralph Droms, Cenk Guendogan, Rahul Jadhav, Matthias
	Kovatsch, Peter van der Stok, Xavier Vilajosana and Thomas Watteyne.		Kovatsch, Peter van der Stok, Xavier Vilajosana and Thomas Watteyne.
	13. References		13. References
	13.1. Normative References		13.1. Normative References
			[BCP38] Ferguson, P. and D. Senie, "Network Ingress Filtering:
			Defeating Denial of Service Attacks which employ IP Source
			Address Spoofing", BCP 38, RFC 2827, DOI 10.17487/RFC2827,
			May 2000, <https://www.rfc-editor.org/info/bcp38>.
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119,		Requirement Levels", BCP 14, RFC 2119,
	DOI 10.17487/RFC2119, March 1997,		DOI 10.17487/RFC2119, March 1997,
	<https://www.rfc-editor.org/info/rfc2119>.		<https://www.rfc-editor.org/info/rfc2119>.
	[RFC2827] Ferguson, P. and D. Senie, "Network Ingress Filtering:		[RFC6040] Briscoe, B., "Tunnelling of Explicit Congestion
	Defeating Denial of Service Attacks which employ IP Source		Notification", RFC 6040, DOI 10.17487/RFC6040, November
	Address Spoofing", BCP 38, RFC 2827, DOI 10.17487/RFC2827,		2010, <https://www.rfc-editor.org/info/rfc6040>.
	May 2000, <https://www.rfc-editor.org/info/rfc2827>.
	[RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J.,		[RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J.,
	Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur,		Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur,
	JP., and R. Alexander, "RPL: IPv6 Routing Protocol for		JP., and R. Alexander, "RPL: IPv6 Routing Protocol for
	Low-Power and Lossy Networks", RFC 6550,		Low-Power and Lossy Networks", RFC 6550,
	DOI 10.17487/RFC6550, March 2012,		DOI 10.17487/RFC6550, March 2012,
	<https://www.rfc-editor.org/info/rfc6550>.		<https://www.rfc-editor.org/info/rfc6550>.
	[RFC6553] Hui, J. and JP. Vasseur, "The Routing Protocol for Low-		[RFC6553] Hui, J. and JP. Vasseur, "The Routing Protocol for Low-
	Power and Lossy Networks (RPL) Option for Carrying RPL		Power and Lossy Networks (RPL) Option for Carrying RPL
	skipping to change at page 49, line 35 ¶		skipping to change at page 52, line 14 ¶
	[DDOS-KREBS]		[DDOS-KREBS]
	Goodin, D., "Record-breaking DDoS reportedly delivered by		Goodin, D., "Record-breaking DDoS reportedly delivered by
	>145k hacked cameras", September 2016,		>145k hacked cameras", September 2016,
	<http://arstechnica.com/security/2016/09/botnet-of-145k-		<http://arstechnica.com/security/2016/09/botnet-of-145k-
	cameras-reportedly-deliver-internets-biggest-ddos-ever/>.		cameras-reportedly-deliver-internets-biggest-ddos-ever/>.
	[I-D.ietf-6lo-ap-nd]		[I-D.ietf-6lo-ap-nd]
	Thubert, P., Sarikaya, B., Sethi, M., and R. Struik,		Thubert, P., Sarikaya, B., Sethi, M., and R. Struik,
	"Address Protected Neighbor Discovery for Low-power and		"Address Protected Neighbor Discovery for Low-power and
	Lossy Networks", draft-ietf-6lo-ap-nd-11 (work in		Lossy Networks", draft-ietf-6lo-ap-nd-12 (work in
	progress), February 2019.		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]		[I-D.ietf-anima-autonomic-control-plane]
	Eckert, T., Behringer, M., and S. Bjarnason, "An Autonomic		Eckert, T., Behringer, M., and S. Bjarnason, "An Autonomic
	Control Plane (ACP)", draft-ietf-anima-autonomic-control-		Control Plane (ACP)", draft-ietf-anima-autonomic-control-
	plane-18 (work in progress), August 2018.		plane-19 (work in progress), March 2019.
	[I-D.ietf-anima-bootstrapping-keyinfra]		[I-D.ietf-anima-bootstrapping-keyinfra]
	Pritikin, M., Richardson, M., Behringer, M., Bjarnason,		Pritikin, M., Richardson, M., Behringer, M., Bjarnason,
	S., and K. Watsen, "Bootstrapping Remote Secure Key		S., and K. Watsen, "Bootstrapping Remote Secure Key
	Infrastructures (BRSKI)", draft-ietf-anima-bootstrapping-		Infrastructures (BRSKI)", draft-ietf-anima-bootstrapping-
	keyinfra-19 (work in progress), March 2019.		keyinfra-20 (work in progress), May 2019.
			[I-D.ietf-intarea-tunnels]
			Touch, J. and M. Townsley, "IP Tunnels in the Internet
			Architecture", draft-ietf-intarea-tunnels-09 (work in
			progress), July 2018.
	[I-D.thubert-roll-unaware-leaves]		[I-D.thubert-roll-unaware-leaves]
	Thubert, P., "Routing for RPL Leaves", draft-thubert-roll-		Thubert, P., "Routing for RPL Leaves", draft-thubert-roll-
	unaware-leaves-06 (work in progress), November 2018.		unaware-leaves-07 (work in progress), April 2019.
			[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
			(IPv6) Specification", RFC 2460, DOI 10.17487/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
	Control Message Protocol (ICMPv6) for the Internet		Control Message Protocol (ICMPv6) for the Internet
	Protocol Version 6 (IPv6) Specification", STD 89,		Protocol Version 6 (IPv6) Specification", STD 89,
	RFC 4443, DOI 10.17487/RFC4443, March 2006,		RFC 4443, DOI 10.17487/RFC4443, March 2006,
	<https://www.rfc-editor.org/info/rfc4443>.		<https://www.rfc-editor.org/info/rfc4443>.
End of changes. 202 change blocks.
	876 lines changed or deleted		1028 lines changed or added
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