< draft-ietf-roll-useofrplinfo-34.txt		draft-ietf-roll-useofrplinfo-35.txt >
	ROLL Working Group M. Robles		ROLL Working Group M. Robles
	Internet-Draft Aalto/UTN-FRM		Internet-Draft UTN-FRM/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: July 23, 2020 P. Thubert		Expires: August 15, 2020 P. Thubert
	Cisco		Cisco
	January 20, 2020		February 12, 2020
	Using RPI Option Type, Routing Header for Source Routes and IPv6-in-IPv6		Using RPI 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-34		draft-ietf-roll-useofrplinfo-35
	Abstract		Abstract
	This document looks at different data flows through LLN (Low-Power		This document looks at different data flows through LLN (Low-Power
	and Lossy Networks) where RPL (IPv6 Routing Protocol for Low-Power		and Lossy Networks) where RPL (IPv6 Routing Protocol for Low-Power
	and Lossy Networks) is used to establish routing. The document		and Lossy Networks) is used to establish routing. The document
	enumerates the cases where RFC6553 (RPI Option Type), RFC6554		enumerates the cases where RFC6553 (RPI Option Type), RFC6554
	(Routing Header for Source Routes) and IPv6-in-IPv6 encapsulation is		(Routing Header for Source Routes) and IPv6-in-IPv6 encapsulation is
	required in data plane. This analysis provides the basis on which to		required in data plane. This analysis provides the basis on which to
	design efficient compression of these headers. This document updates		design efficient compression of these headers. This document updates
	skipping to change at page 1, line 44 ¶		skipping to change at page 1, line 44 ¶
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at https://datatracker.ietf.org/drafts/current/.		Drafts is at https://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	This Internet-Draft will expire on July 23, 2020.		This Internet-Draft will expire on August 15, 2020.
	Copyright Notice		Copyright Notice
	Copyright (c) 2020 IETF Trust and the persons identified as the		Copyright (c) 2020 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(https://trustee.ietf.org/license-info) in effect on the date of		(https://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	skipping to change at page 3, line 4 ¶		skipping to change at page 3, line 4 ¶
	7.2.1. SM: Example of Flow from RAL to Internet . . . . . . 23		7.2.1. SM: Example of Flow from RAL to Internet . . . . . . 23
	7.2.2. SM: Example of Flow from Internet to RAL . . . . . . 24		7.2.2. SM: Example of Flow from Internet to RAL . . . . . . 24
	7.2.3. SM: Example of Flow from RUL to Internet . . . . . . 25		7.2.3. SM: Example of Flow from RUL to Internet . . . . . . 25
	7.2.4. SM: Example of Flow from Internet to RUL. . . . . . . 26		7.2.4. SM: Example of Flow from Internet to RUL. . . . . . . 26
	7.3. SM: Interaction between Leaf and Leaf . . . . . . . . . . 27		7.3. SM: Interaction between Leaf and Leaf . . . . . . . . . . 27
	7.3.1. SM: Example of Flow from RAL to RAL . . . . . . . . . 27		7.3.1. SM: Example of Flow from RAL to RAL . . . . . . . . . 27
	7.3.2. SM: Example of Flow from RAL to RUL . . . . . . . . . 28		7.3.2. SM: Example of Flow from RAL to RUL . . . . . . . . . 28
	7.3.3. SM: Example of Flow from RUL to RAL . . . . . . . . . 29		7.3.3. SM: Example of Flow from RUL to RAL . . . . . . . . . 29
	7.3.4. SM: Example of Flow from RUL to RUL . . . . . . . . . 30		7.3.4. SM: Example of Flow from RUL to RUL . . . . . . . . . 30
	8. Non Storing mode . . . . . . . . . . . . . . . . . . . . . . 31		8. Non Storing mode . . . . . . . . . . . . . . . . . . . . . . 31
	8.1. Non-Storing Mode: Interaction between Leaf and Root . . . 32		8.1. Non-Storing Mode: Interaction between Leaf and Root . . . 33
	8.1.1. Non-SM: Example of Flow from RAL to root . . . . . . 33		8.1.1. Non-SM: Example of Flow from RAL to root . . . . . . 34
	8.1.2. Non-SM: Example of Flow from root to RAL . . . . . . 33		8.1.2. Non-SM: Example of Flow from root to RAL . . . . . . 34
	8.1.3. Non-SM: Example of Flow from root to RUL . . . . . . 34		8.1.3. Non-SM: Example of Flow from root to RUL . . . . . . 35
	8.1.4. Non-SM: Example of Flow from RUL to root . . . . . . 35		8.1.4. Non-SM: Example of Flow from RUL to root . . . . . . 36
	8.2. Non-Storing Mode: Interaction between Leaf and Internet . 36		8.2. Non-Storing Mode: Interaction between Leaf and Internet . 37
	8.2.1. Non-SM: Example of Flow from RAL to Internet . . . . 36		8.2.1. Non-SM: Example of Flow from RAL to Internet . . . . 37
	8.2.2. Non-SM: Example of Flow from Internet to RAL . . . . 37		8.2.2. Non-SM: Example of Flow from Internet to RAL . . . . 38
	8.2.3. Non-SM: Example of Flow from RUL to Internet . . . . 38		8.2.3. Non-SM: Example of Flow from RUL to Internet . . . . 39
	8.2.4. Non-SM: Example of Flow from Internet to RUL . . . . 39		8.2.4. Non-SM: Example of Flow from Internet to RUL . . . . 40
	8.3. Non-SM: Interaction between Leafs . . . . . . . . . . . . 40		8.3. Non-SM: Interaction between Leafs . . . . . . . . . . . . 41
	8.3.1. Non-SM: Example of Flow from RAL to RAL . . . . . . . 40		8.3.1. Non-SM: Example of Flow from RAL to RAL . . . . . . . 41
	8.3.2. Non-SM: Example of Flow from RAL to RUL . . . . . . . 42		8.3.2. Non-SM: Example of Flow from RAL to RUL . . . . . . . 44
	8.3.3. Non-SM: Example of Flow from RUL to RAL . . . . . . . 43		8.3.3. Non-SM: Example of Flow from RUL to RAL . . . . . . . 46
	8.3.4. Non-SM: Example of Flow from RUL to RUL . . . . . . . 44		8.3.4. Non-SM: Example of Flow from RUL to RUL . . . . . . . 47
	9. Operational Considerations of supporting		9. Operational Considerations of supporting
	RUL-leaves . . . . . . . . . . . . . . . . . . . . . . . . . 45		RUL-leaves . . . . . . . . . . . . . . . . . . . . . . . . . 48
	10. Operational considerations of introducing 0x23 . . . . . . . 46		10. Operational considerations of introducing 0x23 . . . . . . . 49
	11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 46		11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 49
	12. Security Considerations . . . . . . . . . . . . . . . . . . . 47		12. Security Considerations . . . . . . . . . . . . . . . . . . . 50
	13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 50		13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 53
	14. References . . . . . . . . . . . . . . . . . . . . . . . . . 51		14. References . . . . . . . . . . . . . . . . . . . . . . . . . 54
	14.1. Normative References . . . . . . . . . . . . . . . . . . 51		14.1. Normative References . . . . . . . . . . . . . . . . . . 54
	14.2. Informative References . . . . . . . . . . . . . . . . . 52		14.2. Informative References . . . . . . . . . . . . . . . . . 55
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 54		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 57
	1. Introduction		1. Introduction
	RPL (IPv6 Routing Protocol for Low-Power and Lossy Networks)		RPL (IPv6 Routing Protocol for Low-Power and Lossy Networks)
	[RFC6550] is a routing protocol for constrained networks. [RFC6553]		[RFC6550] is a routing protocol for constrained networks. [RFC6553]
	defines the RPL Option carried within the IPv6 Hop-by-Hop Header to		defines the RPL Option carried within the IPv6 Hop-by-Hop Header to
	carry the RPLInstanceID and quickly identify inconsistencies (loops)		carry the RPLInstanceID and quickly identify inconsistencies (loops)
	in the routing topology. The RPL Option is commonly referred to as		in the routing topology. The RPL Option is commonly referred to as
	the RPL Packet Information (RPI) though the RPI is really the		the RPL Packet Information (RPI) though the RPI is really the
	abstract information that is defined in [RFC6550] and transported in		abstract information that is defined in [RFC6550] and transported in
	skipping to change at page 20, line 5 ¶		skipping to change at page 20, line 5 ¶
	(loops) in the routing topology. In all cases the RH3 is not needed		(loops) in the routing topology. In all cases the RH3 is not needed
	because it is not used in storing mode.		because it is not used in storing mode.
	In each case, 6LR_i are the intermediate routers from source to		In each case, 6LR_i are the intermediate routers from source to
	destination. "1 <= i <= n", n is the number of routers (6LR) that		destination. "1 <= i <= n", n is the number of routers (6LR) that
	the packet goes through from source (6LN) to destination.		the packet goes through from source (6LN) to destination.
	The leaf can be a router 6LR or a host, both indicated as 6LN. The		The leaf can be a router 6LR or a host, both indicated as 6LN. The
	root refers to the 6LBR (see Figure 6).		root refers to the 6LBR (see Figure 6).
	+---------------------+--------------+------------+------------------+		+---------------------+--------------+------------+----------------+
	| Interaction between | Use Case |IPv6-in-IPv6| IPv6-in-IPv6 dst |		| Interaction between | Use Case |IPv6-in-IPv6|IPv6-in-IPv6 dst|
	+---------------------+--------------+------------+------------------+		+---------------------+--------------+------------+----------------+
	| | RAL to root | No | No |		| | RAL to root | No | No |
	+ +--------------+------------+------------------+		+ +--------------+------------+----------------+
	| Leaf - Root | root to RAL | No | No |		| Leaf - Root | root to RAL | No | No |
	+ +--------------+------------+------------------+		+ +--------------+------------+----------------+
	| | root to RUL | No | No |		| | root to RUL | No | No |
	+ +--------------+------------+------------------+		+ +--------------+------------+----------------+
	| | RUL to root | must | root |		| | RUL to root | must | root |
	+---------------------+--------------+------------+------------------+		+---------------------+--------------+------------+----------------+
	| | RAL to Int | No | No |		| | RAL to Int | No | No |
	+ +--------------+------------+------------------+		+ +--------------+------------+----------------+
	| Leaf - Internet | Int to RAL | must | RAL (tgt) |		| Leaf - Internet | Int to RAL | must | RAL (tgt) |
	+ +--------------+------------+------------------+		+ +--------------+------------+----------------+
	| | RUL to Int | must | root |		| | RUL to Int | must | root |
	+ +--------------+------------+------------------+		+ +--------------+------------+----------------+
	| | Int to RUL | must | 6LR |		| | Int to RUL | must | 6LR |
	+---------------------+--------------+------------+------------------+		+---------------------+--------------+------------+----------------+
	| | RAL to RAL | No | No |		| | RAL to RAL | No | No |
	+ +--------------+------------+------------------+		+ +--------------+------------+----------------+
	| | RAL to RUL | No | No |		| | RAL to RUL | No | No |
	+ Leaf - Leaf +--------------+------------+------------------+		+ Leaf - Leaf +--------------+------------+----------------+
	| | RUL to RAL | must | root/RAL(tgt) |		| | RUL to RAL | must | root |
	+ +--------------+------------+------------------+		+ +--------------+------------+----------------+
	| | RUL to RUL | must | root/6LR |		| | RUL to RUL | must | root |
	+---------------------+--------------+------------+------------------+		+---------------------+--------------+------------+----------------+
	Figure 7: Table of IPv6-in-IPv6 encapsulation in Storing mode.		Figure 7: Table of IPv6-in-IPv6 encapsulation in Storing mode.
	7.1. Storing Mode: Interaction between Leaf and Root		7.1. Storing Mode: Interaction between Leaf and Root
	In this section is described the communication flow in storing mode		In this section is described the communication flow in storing mode
	(SM) between,		(SM) between,
	RAL to root		RAL to root
	skipping to change at page 23, line 13 ¶		skipping to change at page 23, line 13 ¶
	(6LR_1)--> Node B (6LR_i)--> Node A root(6LBR)		(6LR_1)--> Node B (6LR_i)--> 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, encapsulated in a IPv6-in-IPv6 header.		the 6LR_1 will insert a RPI, encapsulated in a IPv6-in-IPv6 header.
	The IPv6-in-IPv6 header is addressed to the root (Node A). The root		The IPv6-in-IPv6 header is addressed to the root (Node A). The root
	removes the header and processes the packet.		removes the header and processes the packet.
	The Figure 8 shows the table that summarizes what headers are needed		The Figure 8 shows the table that summarizes what headers are needed
	for this use case where the IPv6-in-IPv6 header is addressed to the		for this use case where the IPv6-in-IPv6 header is addressed to the
	root (Node A).		root (Node A).
	+-----------+------+--------------+-----------------+------------------+		+-----------+------+--------------+----------------+-----------------+
	| Header | RUL | 6LR_1 | 6LR_i | 6LBR dst |		| Header | RUL | 6LR_1 | 6LR_i | 6LBR dst |
	| | src | | | |		| | src | | | |
	| | node | | | |		| | node | | | |
	+-----------+------+--------------+-----------------+------------------+		+-----------+------+--------------+----------------+-----------------+
	| Added | -- | IP6-IP6(RPI) | | -- |		| Added | -- | IP6-IP6(RPI) | | -- |
	| headers | | | | |		| headers | | | | |
	+-----------+------+--------------+-----------------+------------------+		+-----------+------+--------------+----------------+-----------------+
	| Modified | -- | -- | IP6-IP6(RPI) | -- |		| Modified | -- | -- | IP6-IP6(RPI) | -- |
	| headers | | | | |		| headers | | | | |
	+-----------+------+--------------+-----------------+------------------+		+-----------+------+--------------+----------------+-----------------+
	| Removed | -- | -- | | IP6-IP6(RPI) |		| Removed | -- | -- | | IP6-IP6(RPI) |
	| headers | | | | |		| headers | | | | |
	+-----------+------+--------------+-----------------+------------------+		+-----------+------+--------------+----------------+-----------------+
	| Untouched | -- | -- | -- | -- |		| Untouched | -- | -- | -- | -- |
	| headers | | | | |		| headers | | | | |
	+-----------+------+--------------+-----------------+------------------+		+-----------+------+--------------+----------------+-----------------+
	Figure 8: SM: Summary of the use of headers from RUL to root.		Figure 8: SM: Summary of the use of headers from RUL to root.
	7.2. SM: Interaction between Leaf and Internet.		7.2. SM: Interaction between Leaf and Internet.
	In this section is described the communication flow in storing mode		In this section is described the communication flow in storing mode
	(SM) between,		(SM) between,
	RAL to Internet		RAL to Internet
	skipping to change at page 26, line 5 ¶		skipping to change at page 26, line 5 ¶
	modified.		modified.
	The originating node will ideally leave the IPv6 flow label as zero		The originating node will ideally leave the IPv6 flow label as zero
	so that the packet can be better compressed through the LLN. The		so that the packet can be better compressed through the LLN. The
	6LBR will set the flow label of the packet to a non-zero value when		6LBR will set the flow label of the packet to a non-zero value when
	sending to the Internet, for details check [RFC6437].		sending to the Internet, for details check [RFC6437].
	The Figure 10 shows the table that summarizes what headers are needed		The Figure 10 shows the table that summarizes what headers are needed
	for this use case.		for this use case.
	+---------+-------+------------+--------------+-------------+--------+		+---------+-------+------------+-------------+-------------+--------+
	| Header | IPv6 | 6LR_1 | 6LR_i | 6LBR |Internet|		| Header | IPv6 | 6LR_1 | 6LR_i | 6LBR |Internet|
	| | src | | [i=2,...,n] | | dst |		| | src | | [i=2,...,n] | | dst |
	| | node | | | | |		| | node | | | | |
	| | (RUL) | | | | |		| | (RUL) | | | | |
	+---------+-------+------------+--------------+-------------+--------+		+---------+-------+------------+-------------+-------------+--------+
	| Added | -- |IP6-IP6(RPI)| -- | -- | -- |		| Added | -- |IP6-IP6(RPI)| -- | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	+---------+-------+------------+--------------+-------------+--------+		+---------+-------+------------+-------------+-------------+--------+
	| Modified| -- | -- | IP6-IP6(RPI) | -- | -- |		| Modified| -- | -- |IP6-IP6(RPI) | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	+---------+-------+------------+--------------+-------------+--------+		+---------+-------+------------+-------------+-------------+--------+
	| Removed | -- | -- | -- | IP6-IP6(RPI)| -- |		| Removed | -- | -- | -- | IP6-IP6(RPI)| -- |
	| headers | | | | | |		| headers | | | | | |
	+---------+-------+------------+--------------+-------------+--------+		+---------+-------+------------+-------------+-------------+--------+
	|Untouched| -- | -- | -- | -- | -- |		|Untouched| -- | -- | -- | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	+---------+-------+------------+--------------+-------------+--------+		+---------+-------+------------+-------------+-------------+--------+
	Figure 10: SM: Summary of the use of headers from RUL to Internet.		Figure 10: SM: Summary of the use of headers from RUL to Internet.
	7.2.4. SM: Example of Flow from Internet to RUL.		7.2.4. SM: Example of Flow from Internet to RUL.
	In this case the flow comprises:		In this case the flow comprises:
	Internet --> root (6LBR) --> 6LR_i --> RUL (IPv6 dst node)		Internet --> root (6LBR) --> 6LR_i --> RUL (IPv6 dst node)
	For example, a communication flow could be: Internet --> Node A		For example, a communication flow could be: Internet --> Node A
	skipping to change at page 27, line 5 ¶		skipping to change at page 27, line 5 ¶
	Further details about this are mentioned in		Further details about this are mentioned in
	[I-D.ietf-roll-unaware-leaves], which specifies RPL routing for a 6LN		[I-D.ietf-roll-unaware-leaves], which specifies RPL routing for a 6LN
	acting as a plain host and not being aware of RPL.		acting as a plain host and not being 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 [RFC8138][RFC6437].		zero in order to aid in compression [RFC8138][RFC6437].
	The Figure 11 shows the table that summarizes what headers are needed		The Figure 11 shows the table that summarizes what headers are needed
	for this use case.		for this use case.
	+---------+-------+------------+--------------+-------------+--------+		+---------+-------+------------+--------------+-------------+-------+
	| Header |Inter- | 6LBR | 6LR_i | 6LR_n | RUL |		| Header |Inter- | 6LBR | 6LR_i | 6LR_n | RUL |
	| | net | |[i=1,..,n-1] | | dst |		| | net | |[i=1,..,n-1] | | dst |
	| | src | | | | |		| | src | | | | |
	| | | | | | |		| | | | | | |
	+---------+-------+------------+--------------+-------------+--------+		+---------+-------+------------+--------------+-------------+-------+
	| Inserted| -- |IP6-IP6(RPI)| | -- | -- |		| Inserted| -- |IP6-IP6(RPI)| | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	+---------+-------+------------+--------------+-------------+--------+		+---------+-------+------------+--------------+-------------+-------+
	| Modified| -- | -- | IP6-IP6(RPI) | -- | -- |		| Modified| -- | -- | IP6-IP6(RPI) | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	+---------+-------+------------+--------------+-------------+--------+		+---------+-------+------------+--------------+-------------+-------+
	| Removed | -- | -- | | IP6-IP6(RPI)| -- |		| Removed | -- | -- | | IP6-IP6(RPI)| -- |
	| headers | | | | | |		| headers | | | | | |
	+---------+-------+------------+--------------+-------------+--------+		+---------+-------+------------+--------------+-------------+-------+
	|Untouched| -- | -- | -- | -- | -- |		|Untouched| -- | -- | -- | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	+---------+-------+------------+--------------+-------------+--------+		+---------+-------+------------+--------------+-------------+-------+
	Figure 11: SM: Summary of the use of headers from Internet to RUL.		Figure 11: SM: Summary of the use of headers from Internet to RUL.
	7.3. SM: Interaction between Leaf and Leaf		7.3. SM: Interaction between Leaf and Leaf
	In this section is described the communication flow in storing mode		In this section is described the communication flow in storing mode
	(SM) between,		(SM) between,
	RAL to RAL		RAL to RAL
	skipping to change at page 31, line 50 ¶		skipping to change at page 31, line 50 ¶
	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 RPL-unaware		no need for all nodes to know about the existence of RPL-unaware
	nodes. Only the 6LBR needs to act if compensation is necessary for		nodes. Only the 6LBR needs to act if compensation is necessary for
	not-RPL aware receivers.		not-RPL aware receivers.
	The table (Figure 14) summarizes what headers are needed in the		The table (Figure 14) summarizes what headers are needed in the
	following scenarios, and indicates when the RPI, RH3 and IPv6-in-IPv6		following scenarios, and indicates when the RPI, RH3 and IPv6-in-IPv6
	header are to be inserted. It depicts the target destination address		header are to be inserted. It depicts the target destination address
	possible to a 6LN (indicated by "RAL"), to a 6LR (parent of a 6LN) or		possible to a 6LN (indicated by "RAL"), to a 6LR (parent of a RUL) or
	to the root. In cases where no IPv6-in-IPv6 header is needed, the		to the root. In cases where no IPv6-in-IPv6 header is needed, the
	column states as "No". There is no expectation on RPL that RPI can		column states as "No". There is no expectation on RPL that RPI can
	be omitted, because it is needed for routing, quality of service and		be omitted, because it is needed for routing, quality of service and
	compression. This specification expects that is always a RPI		compression. This specification expects that is always a RPI
	Present.		Present. The term "may(up)" refers that the IPv6-in-IPv6 header may
			be necessary in the upwards direction. The term "must(up)" refers
			that the IPv6-in-IPv6 header must be present in the upwards
			direction. The term "must(down)" refers that the IPv6-in-IPv6 header
			must be present in the downward direction.
	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 6). In the table (Figure 14) the (1) indicates a 6tisch case		(Figure 6). In the table (Figure 14) the (1) indicates a 6tisch case
	[RFC8180], where the RPI may still be needed for the instanceID to be		[RFC8180], where the RPI may still be needed for the instanceID to be
	available for priority/channel selection at each hop.		available for priority/channel selection at each hop.
	+-----------------+--------------+-----+-----+------------+------------+		The root always have to encapuslate on the way down
	| Interaction | Use Case | RPI | RH3 |IPv6-in-IPv6|IPv6-in-IPv6|
	| between | | | | | dst |		+--- ------------+-------------+-----+-----+--------------+----------+
	+-----------------+--------------+-----+-----+------------+------------+		| Interaction | Use Case | RPI | RH3 | IPv6-in-IPv6 | IP-in-IP |
	| | RAL to root | Yes | No | No | No |		| between | | | | | dst |
	+ +--------------+-----+-----+------------+------------+		+----------------+-------------+-----+-----+--------------+----------+
	| Leaf - Root | root to RAL | Yes | Yes | No | No |		| | RAL to root | Yes | No | No | No |
	+ +--------------+-----+-----+------------+------------+		| +-------------+-----+-----+--------------+----------+
	| | root to RUL | Yes | Yes | must | 6LR |		| Leaf - Root | root to RAL | Yes | Yes | No | No |
	| | | (1) | | | |		| +-------------+-----+-----+--------------+----------+
	+ +--------------+-----+-----+------------+------------+		| | root to RUL | Yes | Yes | must | 6LR |
	| | RUL to root | Yes | No | must | root |		| | | (1) | | | |
	+-----------------+--------------+-----+-----+------------+------------+		| +-------------+-----+-----+--------------+----------+
	| | RAL to Int | Yes | No | No | No |		| | RUL to root | Yes | No | must | root |
	+ +--------------+-----+-----+------------+------------+		+----------------+-------------+-----+-----+--------------+----------+
	| Leaf - Internet | Int to RAL | Yes | Yes | must | RAL |		| | RAL to Int | Yes | No | may(up) | root |
	+ +--------------+-----+-----+------------+------------+		| +-------------+-----+-----+--------------+----------+
	| | RUL to Int | Yes | No | must | root |		|Leaf - Internet | Int to RAL | Yes | Yes | must | RAL |
	+ +--------------+-----+-----+------------+------------+		| +-------------+-----+-----+--------------+----------+
	| | Int to RUL | Yes | Yes | must | 6LR |		| | RUL to Int | Yes | No | must | root |
	+-----------------+--------------+-----+-----+------------+------------+		| +-------------+-----+-----+--------------+----------+
	| | RAL to RAL | Yes | Yes | must | root/RAL |		| | Int to RUL | Yes | Yes | must | 6LR |
	+ +--------------+-----+-----+------------+------------+		+----------------+-------------+-----+-----+--------------+----------+
	| | RAL to RUL | Yes | Yes | must | root/6LR |		| | RAL to RAL | Yes | Yes | may(up) | root |
	+ Leaf - Leaf +--------------+-----+-----+------------+------------+		| | | | +--------------+----------+
	| | RUL to RAL | Yes | Yes | must | root/RAL |		| | | | | must(down) | RAL |
	+ +--------------+-----+-----+------------+------------+		| Leaf - Leaf +-------------+-----+-----+--------------+----------+
	| | RUL to RUL | Yes | Yes | must | root/6LR |		| | RAL to RUL | Yes | Yes | may(up) | root |
	+-----------------+--------------+-----+-----+------------+------------+		| | | | +--------------+----------+
			| | | | | must(down) | 6LR |
			| +-------------+-----+-----+--------------+----------+
			| | RUL to RAL | Yes | Yes | must(up) | root |
			| | | | +--------------+----------+
			| | | | | must(down) | RAL |
			| +-------------+-----+-----+--------------+----------+
			| | RUL to RUL | Yes | Yes | must(up) | root |
			| | | | +--------------+----------+
			| | | | | must(down) | 6LR |
			+----------------+-------------+-----+-----+--------------+----------+
	Figure 14: Table that shows headers needed in Non-Storing mode: RPI,		Figure 14: Table that shows headers needed in Non-Storing mode: RPI,
	RH3, IPv6-in-IPv6 encapsulation.		RH3, IPv6-in-IPv6 encapsulation.
	8.1. Non-Storing Mode: Interaction between Leaf and Root		8.1. Non-Storing Mode: Interaction between Leaf and Root
	In this section is described the communication flow in Non Storing		In this section is described the communication flow in Non Storing
	Mode (Non-SM) between,		Mode (Non-SM) between,
	RAL to root
			RAL to root
	root to RAL		root to RAL
	RUL to root		RUL to root
	root to RUL		root to RUL
	8.1.1. Non-SM: Example of Flow from RAL to root		8.1.1. Non-SM: Example of Flow from RAL to root
	In non-storing mode the leaf node uses default routing to send		In non-storing mode the leaf node uses default routing to send
	traffic to the root. The RPI must be included since it contains the		traffic to the root. The RPI must be included since it contains the
	skipping to change at page 33, line 35 ¶		skipping to change at page 34, line 33 ¶
	packet goes through from source (RAL) to destination (6LBR).		packet goes through from source (RAL) to destination (6LBR).
	This situation is the same case as storing mode.		This situation is the same case as storing mode.
	The Table 7 summarizes what headers are needed for this use case.		The Table 7 summarizes what headers are needed for this use case.
	+-------------------+---------+-------+----------+		+-------------------+---------+-------+----------+
	| Header | RAL src | 6LR_i | 6LBR dst |		| Header | RAL src | 6LR_i | 6LBR dst |
	+-------------------+---------+-------+----------+		+-------------------+---------+-------+----------+
	| Added headers | RPI | -- | -- |		| Added headers | RPI | -- | -- |
	| Removed headers | -- | -- | RPI |
	| Modified headers | -- | RPI | -- |		| Modified headers | -- | RPI | -- |
			| Removed headers | -- | -- | RPI |
	| Untouched headers | -- | -- | -- |		| Untouched headers | -- | -- | -- |
	+-------------------+---------+-------+----------+		+-------------------+---------+-------+----------+
	Table 7: Non-SM: Summary of the use of headers from RAL to root		Table 7: Non-SM: Summary of the use of headers from RAL to root
	8.1.2. Non-SM: Example of Flow from root to RAL		8.1.2. Non-SM: Example of Flow from root to RAL
	In this case the flow comprises:		In this case the flow comprises:
	root (6LBR) --> 6LR_i --> RAL (6LN)		root (6LBR) --> 6LR_i --> RAL (6LN)
	skipping to change at page 34, line 33 ¶		skipping to change at page 35, line 30 ¶
	Table 8: Non-SM: Summary of the use of headers from root to RAL		Table 8: Non-SM: Summary of the use of headers from root to RAL
	8.1.3. Non-SM: Example of Flow from root to RUL		8.1.3. Non-SM: Example of Flow from root to RUL
	In this case the flow comprises:		In this case the flow comprises:
	root (6LBR) --> 6LR_i --> RUL (IPv6 dst node)		root (6LBR) --> 6LR_i --> RUL (IPv6 dst node)
	For example, a communication flow could be: Node A (root) --> Node B		For example, a communication flow could be: Node A (root) --> Node B
	--> Node E --> Node G		--> Node E --> Node G (RUL)
	6LR_i are the intermediate routers from source to destination. In		6LR_i are the intermediate routers from source to destination. In
	this case, "1 <= i <= n", n is the number of routers (6LR) that the		this case, "1 <= i <= n", n is the number of routers (6LR) that the
	packet goes through from source (6LBR) to destination (RUL).		packet goes through from source (6LBR) to destination (RUL).
	In 6LBR the RH3 is added, it is modified at each intermediate 6LR		In the 6LBR the RH3 is added, it is modified at each intermediate 6LR
	(6LR_1 and so on) and it is fully consumed in the last 6LR (6LR_n),		(6LR_1 and so on) and it is fully consumed in the last 6LR (6LR_n),
	but left there. As the RPI is added, then the IPv6 node which does		but left there. As the RPI is added, then the IPv6 node which does
	not understand the RPI, will ignore it (following RFC8200), thus		not understand the RPI, will ignore it (following RFC8200), thus
	encapsulation is not necessary.		encapsulation is not necessary.
	The Figure 15 depicts the table that summarizes what headers are		The Figure 15 depicts the table that summarizes what headers are
	needed for this use case.		needed for this use case.
	+-----------+----------+--------------+----------------+----------+		+-----------+----------+--------------+----------------+----------+
	| Header | 6LBR | 6LR_i | 6LR_n | RUL |		| Header | 6LBR | 6LR_i | 6LR_n | RUL |
	skipping to change at page 36, line 51 ¶		skipping to change at page 38, line 5 ¶
	RAL (6LN) src --> 6LR_i --> root (6LBR) --> Internet dst		RAL (6LN) src --> 6LR_i --> root (6LBR) --> Internet dst
	For example, a communication flow could be: Node F (RAL) --> Node D		For example, a communication flow could be: Node F (RAL) --> Node D
	--> Node B --> Node A --> Internet		--> Node B --> Node A --> Internet
	6LR_i are the intermediate routers from source to destination. In		6LR_i are the intermediate routers from source to destination. In
	this case, "1 <= i <= n", n is the number of routers (6LR) that the		this case, "1 <= i <= n", n is the number of routers (6LR) that the
	packet goes through from source (RAL) to 6LBR.		packet goes through from source (RAL) to 6LBR.
	This case is identical to storing-mode case.		In this case, the encapsulation from the RAL to the root is optional.
			The simplest case is when the RPI gets to the Internet (as the table
			show it), knowing that the Internet is going to ignore it.
	The IPv6 flow label should be set to zero to aid in compression		The IPv6 flow label should be set to zero to aid in compression
	[RFC8138], and the 6LBR will set it to a non-zero value when sending		[RFC8138], and the 6LBR will set it to a non-zero value when sending
	towards the Internet [RFC6437].		towards the Internet [RFC6437].
	The Table 9 summarizes what headers are needed for this use case.		The Table 9 summarizes what headers are needed for this use case when
			no encapsulation is used. The Table 10 summarizes what headers are
			needed for this use case when encapsulation to the root is used.
	+-------------------+---------+-------+------+----------------+		+-------------------+---------+-------+------+----------------+
	| Header | RAL src | 6LR_i | 6LBR | Internet dst |		| Header | RAL src | 6LR_i | 6LBR | Internet dst |
	+-------------------+---------+-------+------+----------------+		+-------------------+---------+-------+------+----------------+
	| Added headers | RPI | -- | -- | -- |		| Added headers | RPI | -- | -- | -- |
	| Modified headers | -- | RPI | -- | -- |		| Modified headers | -- | RPI | -- | -- |
	| Removed headers | -- | -- | -- | -- |		| Removed headers | -- | -- | -- | -- |
	| Untouched headers | -- | -- | RPI | RPI (Ignored) |		| Untouched headers | -- | -- | RPI | RPI (Ignored) |
	+-------------------+---------+-------+------+----------------+		+-------------------+---------+-------+------+----------------+
	Table 9: Non-SM: Summary of the use of headers from RAL to Internet		Table 9: Non-SM: Summary of the use of headers from RAL to Internet
			with no encapsulation
			+-----------+--------------+--------------+--------------+----------+
			| Header | RAL src | 6LR_i | 6LBR | Internet |
			| | | | | dst |
			+-----------+--------------+--------------+--------------+----------+
			| Added | IPv6-in-IPv6 | -- | -- | -- |
			| headers | (RPI) | | | |
			| Modified | -- | IPv6-in-IPv6 | -- | -- |
			| headers | | (RPI) | | |
			| Removed | -- | -- | IPv6-in-IPv6 | -- |
			| headers | | | (RPI) | |
			| Untouched | -- | -- | -- | -- |
			| headers | | | | |
			+-----------+--------------+--------------+--------------+----------+
			Table 10: Non-SM: Summary of the use of headers from RAL to Internet
			with encapsulation to the root
	8.2.2. Non-SM: Example of Flow from Internet to RAL		8.2.2. Non-SM: Example of Flow from Internet to RAL
	In this case the flow comprises:		In this case the flow comprises:
	Internet --> root (6LBR) --> 6LR_i --> RAL dst (6LN)		Internet --> root (6LBR) --> 6LR_i --> RAL dst (6LN)
	For example, a communication flow could be: Internet --> Node A		For example, a communication flow could be: Internet --> Node A
	(root) --> Node B --> Node D --> Node F (RAL)		(root) --> Node B --> Node D --> Node F (RAL)
	6LR_i are the intermediate routers from source to destination. In		6LR_i are the intermediate routers from source to destination. In
	this case, "1 <= i <= n", n is the number of routers (6LR) that the		this case, "1 <= i <= n", n is the number of routers (6LR) that the
	packet goes through from 6LBR to destination (RAL).		packet goes through from 6LBR to destination (RAL).
	The 6LBR must add an RH3 header. As the 6LBR will know the path and		The 6LBR must add an RH3 header. As the 6LBR will know the path and
	address of the target node, it can address the IPv6-in-IPv6 header to		address of the target node, it can address the IPv6-in-IPv6 header to
	that node. The 6LBR will zero the flow label upon entry in order to		that node. The 6LBR will zero the flow label upon entry in order to
	aid compression [RFC8138].		aid compression [RFC8138].
	The Table 10 summarizes what headers are needed for this use case.		The Table 11 summarizes what headers are needed for this use case.
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	| Header | Internet | 6LBR | 6LR_i | RAL dst |		| Header | Internet | 6LBR | 6LR_i | RAL dst |
	| | src | | | |		| | src | | | |
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	| Added | -- | IPv6-in-IPv6 | -- | -- |		| Added | -- | IPv6-in-IPv6 | -- | -- |
	| headers | | (RH3,RPI) | | |		| headers | | (RH3,RPI) | | |
	| Modified | -- | -- | IPv6-in-IPv6 | -- |		| Modified | -- | -- | IPv6-in-IPv6 | -- |
	| headers | | | (RH3,RPI) | |		| headers | | | (RH3,RPI) | |
	| Removed | -- | -- | -- | IPv6-in-IPv6 |		| Removed | -- | -- | -- | IPv6-in-IPv6 |
	| headers | | | | (RH3,RPI) |		| headers | | | | (RH3,RPI) |
	| Untouched | -- | -- | -- | -- |		| Untouched | -- | -- | -- | -- |
	| headers | | | | |		| headers | | | | |
	+-----------+----------+--------------+--------------+--------------+		+-----------+----------+--------------+--------------+--------------+
	Table 10: Non-SM: Summary of the use of headers from Internet to RAL		Table 11: Non-SM: Summary of the use of headers from Internet to RAL
	8.2.3. Non-SM: Example of Flow from RUL to Internet		8.2.3. Non-SM: Example of Flow from RUL to Internet
	In this case the flow comprises:		In this case the flow comprises:
	RUL (IPv6 src node) --> 6LR_1 --> 6LR_i -->root (6LBR) --> Internet		RUL (IPv6 src node) --> 6LR_1 --> 6LR_i -->root (6LBR) --> Internet
	dst		dst
	For example, a communication flow could be: Node G --> Node E -->		For example, a communication flow could be: Node G --> Node E -->
	Node B --> Node A --> Internet		Node B --> Node A --> Internet
	skipping to change at page 40, line 22 ¶		skipping to change at page 41, line 22 ¶
	| Modified | -- | -- | IP6-IP6 | -- | -- |		| Modified | -- | -- | IP6-IP6 | -- | -- |
	| headers | | | (RH3,RPI) | | |		| headers | | | (RH3,RPI) | | |
	+----------+--------+------------------+-----------+-----------+-----+		+----------+--------+------------------+-----------+-----------+-----+
	| Removed | -- | -- | -- | IP6-IP6 | -- |		| Removed | -- | -- | -- | IP6-IP6 | -- |
	| headers | | | | (RH3,RPI) | |		| headers | | | | (RH3,RPI) | |
	+----------+--------+------------------+-----------+-----------+-----+		+----------+--------+------------------+-----------+-----------+-----+
	|Untouched | -- | -- | -- | -- | -- |		|Untouched | -- | -- | -- | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	+----------+--------+------------------+-----------+-----------+-----+		+----------+--------+------------------+-----------+-----------+-----+
	Figure 18: Non-SM: Summary of the use of headers from Internet to RUL		Figure 18: Non-SM: Summary of the use of headers from Internet to
	[1] The last 6LR before the IPv6 node.		RUL.
	8.3. Non-SM: Interaction between Leafs		8.3. Non-SM: Interaction between Leafs
	In this section is described the communication flow in Non Storing		In this section is described the communication flow in Non Storing
	Mode (Non-SM) between,		Mode (Non-SM) between,
	RAL to RAL		RAL to RAL
	RAL to RUL		RAL to RUL
	RUL to RAL		RUL to RAL
	RUL to RUL		RUL to RUL
	8.3.1. Non-SM: Example of Flow from RAL to RAL		8.3.1. Non-SM: Example of Flow from RAL to RAL
	In this case the flow comprises:		In this case the flow comprises:
	RAL src --> 6LR_ia --> root (6LBR) --> 6LR_id --> RAL dst		RAL src --> 6LR_ia --> root (6LBR) --> 6LR_id --> RAL dst
	For example, a communication flow could be: Node F --> Node D -->		For example, a communication flow could be: Node F (RAL src)--> Node
	Node B --> Node A (root) --> Node B --> Node E --> Node H		D --> Node B --> Node A (root) --> Node B --> Node E --> Node H (RAL
			dst)
	6LR_ia are the intermediate routers from source to the root In this		6LR_ia are the intermediate routers from source to the root In this
	case, 1 <= ia <= n, n is the number of routers (6LR) that the packet		case, 1 <= ia <= n, n is the number of routers (6LR) that the packet
	goes through from RAL to the root.		goes through from RAL to the root.
	6LR_id are the intermediate routers from the root to the destination.		6LR_id are the intermediate routers from the root to the destination.
	In this case, "1 <= ia <= m", m is the number of the intermediate		In this case, "1 <= ia <= m", m is the number of the intermediate
	routers (6LR).		routers (6LR).
	This case involves only nodes in same RPL Domain. The originating		This case involves only nodes in same RPL Domain. The originating
	node will add a RPI to the original packet, and send the packet		node will add a RPI to the original packet, and send the packet
	upwards.		upwards.
	The originating node must put the RPI (RPI1) into an IPv6-in-IPv6		The originating node may put the RPI (RPI1) into an IPv6-in-IPv6
	header addressed to the root, so that the 6LBR can remove that		header addressed to the root, so that the 6LBR can remove that
	header. If it does not, then additional resources are wasted on the		header. If it does not, then the RPI1 is forwarded down from the
	way down to carry the useless RPI.		root in the inner header to no avail.
	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		add an IPv6-in-IPv6 header. It should be able to remove the
	RPI(RPI1), as it was contained in an IPv6-in-IPv6 header addressed to		RPI(RPI1), as it was contained in an IPv6-in-IPv6 header addressed to
	it. Otherwise, there may be a RPI buried inside the inner IP header,		it. Otherwise, there may be a RPI buried inside the inner IP header,
	which should get ignored. The root inserts a RPI (RPI2) alongside		which should get ignored. The root inserts a RPI (RPI2) alongside
	the RH3.		the RH3.
	Networks that use the RPL P2P extension [RFC6997] are essentially		Networks that use the RPL P2P extension [RFC6997] are essentially
	non-storing DODAGs and fall into this scenario or scenario		non-storing DODAGs and fall into this scenario or scenario
	Section 8.1.2, with the originating node acting as 6LBR.		Section 8.1.2, with the originating node acting as 6LBR.
	The Figure 19 shows the table that summarizes what headers are needed		The Figure 19 shows the table that summarizes what headers are needed
	for this use case.		for this use case when encapsulation to the root takes place.
			The Figure 20 shows the table that summarizes what headers are needed
			for this use case when there is no encapsulation to the root.
	+---------+-------+----------+------------+----------+------------+		+---------+-------+----------+------------+----------+------------+
	| Header | RAL | 6LR_ia | 6LBR | 6LR_id | RAL |		| Header | RAL | 6LR_ia | 6LBR | 6LR_id | RAL |
	| | src | | | | dst |		| | src | | | | dst |
	+---------+-------+----------+------------+----------+------------+		+---------+-------+----------+------------+----------+------------+
	| Added |IP6-IP6| | IP6-IP6 | -- | -- |		| Added |IP6-IP6| | IP6-IP6 | -- | -- |
	| headers |(RPI1) | |(RH3-> RAL, | | |		| headers |(RPI1) | |(RH3-> RAL, | | |
	| | | | RPI2) | | |		| | | | RPI2) | | |
	+---------+-------+----------+------------+----------+------------+		+---------+-------+----------+------------+----------+------------+
	| Modified| -- | IP6-IP6 | -- | IP6-IP6 | -- |		| Modified| -- | IP6-IP6 | -- | IP6-IP6 | -- |
	| headers | | (RPI1) | |(RH3,RPI) | |		| headers | | (RPI1) | |(RH3,RPI) | |
	+---------+-------+----------+------------+----------+------------+		+---------+-------+----------+------------+----------+------------+
	| Removed | -- | -- | IP6-IP6 | -- | IP6-IP6 |		| Removed | -- | -- | IP6-IP6 | -- | IP6-IP6 |
	| headers | | | (RPI1) | | (RH3, |		| headers | | | (RPI1) | | (RH3, |
	| | | | | | RPI2) |		| | | | | | RPI2) |
	+---------+-------+----------+------------+----------+------------+		+---------+-------+----------+------------+----------+------------+
	|Untouched| -- | -- | -- | -- | -- |		|Untouched| -- | -- | -- | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	+---------+-------+----------+------------+----------+------------+		+---------+-------+----------+------------+----------+------------+
	Figure 19: Non-SM: Summary of the use of headers for RAL to RAL.		Figure 19: Non-SM: Summary of the use of headers for RAL to RAL with
			encapsulation to the root.
			+-----------+------+--------+---------+---------+---------+
			| Header | RAL | 6LR_ia | 6LBR | 6LR_id | RAL |
			+-----------+------+--------+---------+---------+---------+
			| Inserted | RPI1 | -- | IP6-IP6 | -- | -- |
			| headers | | | (RH3, | | |
			| | | | RPI2) | | |
			+-----------+------+--------+---------+---------+---------+
			| Modified | -- | RPI1 | -- | IP6-IP6 | -- |
			| headers | | | | (RH3, | |
			| | | | | RPI2) | |
			+-----------+------+--------+---------+---------+---------+
			| Removed | -- | -- | -- | -- | IP6-IP6 |
			| headers | | | | | (RH3, |
			| | | | | | RPI2) |
			| | | | | | RPI1 |
			+-----------+------+--------+---------+---------+---------+
			| Untouched | -- | -- | RPI1 | RPI1 | -- |
			| headers | | | | | |
			+-----------+------+--------+---------+---------+---------+
			Figure 20: Non-SM: Summary of the use of headers for RAL to RAL
			without encapsulation to the root.
	8.3.2. Non-SM: Example of Flow from RAL to RUL		8.3.2. Non-SM: Example of Flow from RAL to RUL
	In this case the flow comprises:		In this case the flow comprises:
	RAL --> 6LR_ia --> root (6LBR) --> 6LR_id --> RUL (IPv6 dst node)		RAL --> 6LR_ia --> root (6LBR) --> 6LR_id --> RUL (IPv6 dst node)
	For example, a communication flow could be: Node F --> Node D -->		For example, a communication flow could be: Node F (RAL) --> Node D
	Node B --> Node A (root) --> Node B --> Node E --> Node G		--> Node B --> Node A (root) --> Node B --> Node E --> Node G (RUL)
	6LR_ia are the intermediate routers from source to the root In this		6LR_ia are the intermediate routers from source to the root In this
	case, 1 <= ia <= n, n is the number of intermediate routers (6LR)		case, 1 <= ia <= n, n is the number of intermediate routers (6LR)
	6LR_id are the intermediate routers from the root to the destination.		6LR_id are the intermediate routers from the root to the destination.
	In this case, "1 <= ia <= m", m is the number of the intermediate		In this case, "1 <= ia <= m", m is the number of the intermediate
	routers (6LRs).		routers (6LRs).
	As in the previous case, the RAL (6LN) will insert a RPI (RPI_1)		As in the previous case, the RAL (6LN) may insert a RPI (RPI1) header
	header which must be in an IPv6-in-IPv6 header addressed to the root		which must be in an IPv6-in-IPv6 header addressed to the root so that
	so that the 6LBR can remove this RPI. The 6LBR will then insert an		the 6LBR can remove this RPI. The 6LBR will then insert an RH3
	RH3 inside a new IPv6-in-IPv6 header addressed to the last 6LR_id		inside a new IPv6-in-IPv6 header addressed to the last 6LR_id (6LR_id
	(6LR_id = m).		= m) alongside the insertion of RPI2.
	The Figure 20 shows the table that summarizes what headers are needed		If the originating node does not not put the RPI (RPI1) into an IPv6-
	for this use case.		in-IPv6 header addressed to the root. Then, the RPI1 is forwarded
			down from the root in the inner header to no avail.
			The Figure 21 shows the table that summarizes what headers are needed
			for this use case when encapsulation to the root takes place. The
			Figure 22 shows the table that summarizes what headers are needed for
			this use case when no encapsulation to the root takes place.
	+-----------+---------+---------+---------+---------+---------+------+		+-----------+---------+---------+---------+---------+---------+------+
	| Header | RAL | 6LR_ia | 6LBR | 6LR_id | 6LR_m | RUL |		| Header | RAL | 6LR_ia | 6LBR | 6LR_id | 6LR_m | RUL |
	| | src | | | | | dst |		| | src | | | | | dst |
	| | node | | | | | node |		| | node | | | | | node |
	+-----------+---------+---------+---------+---------+---------+------+		+-----------+---------+---------+---------+---------+---------+------+
	| Added | IP6-IP6 | | IP6-IP6 | -- | -- | -- |		| Added | IP6-IP6 | | IP6-IP6 | -- | -- | -- |
	| headers | (RPI1) | | (RH3, | | | |		| headers | (RPI1) | | (RH3, | | | |
	| | | | RPI2) | | | |		| | | | RPI2) | | | |
	+-----------+---------+---------+---------+---------+---------+------+		+-----------+---------+---------+---------+---------+---------+------+
	skipping to change at page 42, line 51 ¶		skipping to change at page 45, line 26 ¶
	| | | | | RPI2) | | |		| | | | | RPI2) | | |
	+-----------+---------+---------+---------+---------+---------+------+		+-----------+---------+---------+---------+---------+---------+------+
	| Removed | -- | -- | IP6-IP6 | -- | IP6-IP6 | -- |		| Removed | -- | -- | IP6-IP6 | -- | IP6-IP6 | -- |
	| headers | | | (RPI1) | | (RH3, | |		| headers | | | (RPI1) | | (RH3, | |
	| | | | | | RPI2) | |		| | | | | | RPI2) | |
	+-----------+---------+---------+---------+---------+---------+------+		+-----------+---------+---------+---------+---------+---------+------+
	| Untouched | -- | -- | -- | -- | -- | -- |		| Untouched | -- | -- | -- | -- | -- | -- |
	| headers | | | | | | |		| headers | | | | | | |
	+-----------+---------+---------+---------+---------+---------+------+		+-----------+---------+---------+---------+---------+---------+------+
	Figure 20: Non-SM: Summary of the use of headers from RAL to RUL.		Figure 21: Non-SM: Summary of the use of headers from RAL to RUL with
			encapsulation to the root.
			+-----------+------+--------+---------+---------+---------+---------+
			| Header | RAL | 6LR_ia | 6LBR | 6LR_id | 6LR_n | RUL |
			| | src | | | | | dst |
			| | node | | | | | node |
			+-----------+------+--------+---------+---------+---------+---------+
			| Inserted | RPI1 | -- | IP6-IP6 | -- | -- | -- |
			| headers | | | (RH3, | | | |
			| | | | RPI2) | | | |
			+-----------+------+--------+---------+---------+---------+---------+
			| Modified | -- | RPI1 | -- | IP6-IP6 | -- | -- |
			| headers | | | | (RH3, | | |
			| | | | | RPI2) | | |
			+-----------+------+--------+---------+---------+---------+---------+
			| Removed | -- | -- | -- | -- | IP6-IP6 | -- |
			| headers | | | | | (RH3, | |
			| | | | | | RPI2) | |
			+-----------+------+--------+---------+---------+---------+---------+
			| Untouched | -- | -- | RPI1 | RPI1 | RPI1 | RPI1 |
			| headers | | | | | |(Ignored)|
			+-----------+------+--------+---------+---------+---------+---------+
			Figure 22: Non-SM: Summary of the use of headers from RAL to RUL
			without encapsulation to the root.
	8.3.3. Non-SM: Example of Flow from RUL to RAL		8.3.3. Non-SM: Example of Flow from RUL to RAL
	In this case the flow comprises:		In this case the flow comprises:
	RUL (IPv6 src node) --> 6LR_1 --> 6LR_ia --> root (6LBR) --> 6LR_id		RUL (IPv6 src node) --> 6LR_1 --> 6LR_ia --> root (6LBR) --> 6LR_id
	--> RAL dst (6LN)		--> RAL dst (6LN)
	For example, a communication flow could be: Node G --> Node E -->		For example, a communication flow could be: Node G (RUL)--> Node E
	Node B --> Node A (root) --> Node B --> Node E --> Node H		--> Node B --> Node A (root) --> Node B --> Node E --> Node H (RAL)
	6LR_ia are the intermediate routers from source to the root. In this		6LR_ia are the intermediate routers from source to the root. In this
	case, 1 <= ia <= n, n is the number of intermediate routers (6LR)		case, 1 <= ia <= n, n is the number of intermediate routers (6LR)
	6LR_id are the intermediate routers from the root to the destination.		6LR_id are the intermediate routers from the root to the destination.
	In this case, "1 <= ia <= m", m is the number of the intermediate		In this case, "1 <= ia <= m", m is the number of the intermediate
	routers (6LR).		routers (6LR).
	This scenario is mostly identical to the previous one. The RPI		In this scenario the RPI (RPI1) is added by the first 6LR (6LR_1)
	(RPI1) is added by the first 6LR (6LR_1) inside an IPv6-in-IPv6		inside an IPv6-in-IPv6 header addressed to the root. The 6LBR will
	header addressed to the root. The 6LBR will remove this RPI, and add		remove this RPI, and add it's own IPv6-in-IPv6 header containing an
	it's own IPv6-in-IPv6 header containing an RH3 header and an RPI		RH3 header and an RPI (RPI2).
	(RPI2).
	The Figure 21 shows the table that summarizes what headers are needed		The Figure 23 shows the table that summarizes what headers are needed
	for this use case.		for this use case.
	+-----------+------+---------+---------+---------+---------+---------+		+----------+------+---------+---------+---------+---------+---------+
	| Header | RUL | 6LR_1 | 6LR_ia | 6LBR | 6LR_id | RAL |		| Header | RUL | 6LR_1 | 6LR_ia | 6LBR | 6LR_id | RAL |
	| | src | | | | | dst |		| | src | | | | | dst |
	| | node | | | | | node |		| | node | | | | | node |
	+-----------+------+---------+---------+---------+---------+---------+		+----------+------+---------+---------+---------+---------+---------+
	| Added | -- | IP6-IP6 | -- | IP6-IP6 | -- | -- |		| Added | -- | IP6-IP6 | -- | IP6-IP6 | -- | -- |
	| headers | | (RPI1) | | (RH3, | | |		| headers | | (RPI1) | | (RH3, | | |
	| | | | | RPI2) | | |		| | | | | RPI2) | | |
	+-----------+------+---------+---------+---------+---------+---------+		+----------+------+---------+---------+---------+---------+---------+
	| Modified | -- | | IP6-IP6 | -- | IP6-IP6 | -- |		| Modified | -- | | IP6-IP6 | -- | IP6-IP6 | -- |
	| headers | | | (RPI1) | | (RH3, | |		| headers | | | (RPI1) | | (RH3, | |
	| | | | | | RPI2) | |		| | | | | | RPI2) | |
	+-----------+------+---------+---------+---------+---------+---------+		+----------+------+---------+---------+---------+---------+---------+
	| Removed | -- | | -- | IP6-IP6 | -- | IP6-IP6 |		| Removed | -- | | -- | IP6-IP6 | -- | IP6-IP6 |
	| headers | | | | (RPI1) | | (RH3, |		| headers | | | | (RPI1) | | (RH3, |
	| | | | | | | RPI2) |		| | | | | | | RPI2) |
	+-----------+------+---------+---------+---------+---------+---------+		+----------+------+---------+---------+---------+---------+---------+
	| Untouched | -- | | -- | -- | -- | -- |		|Untouched | -- | | -- | -- | -- | -- |
	| headers | | | | | | |		| headers | | | | | | |
	+-----------+------+---------+---------+---------+---------+---------+		+----------+------+---------+---------+---------+---------+---------+
	Figure 21: Non-SM: Summary of the use of headers from RUL to RAL.		Figure 23: Non-SM: Summary of the use of headers from RUL to RAL.
	8.3.4. Non-SM: Example of Flow from RUL to RUL		8.3.4. Non-SM: Example of Flow from RUL to RUL
	In this case the flow comprises:		In this case the flow comprises:
	RUL (IPv6 src node) --> 6LR_1 --> 6LR_ia --> root (6LBR) --> 6LR_id		RUL (IPv6 src node) --> 6LR_1 --> 6LR_ia --> root (6LBR) --> 6LR_id
	--> RUL (IPv6 dst node)		--> RUL (IPv6 dst node)
	For example, a communication flow could be: Node G --> Node E -->		For example, a communication flow could be: Node G --> Node E -->
	Node B --> Node A (root) --> Node C --> Node J		Node B --> Node A (root) --> Node C --> Node J
	6LR_ia are the intermediate routers from source to the root. In this		6LR_ia are the intermediate routers from source to the root. In this
	case, 1 <= ia <= n, n is the number of intermediate routers (6LR)		case, 1 <= ia <= n, n is the number of intermediate routers (6LR)
	6LR_id are the intermediate routers from the root to the destination.		6LR_id are the intermediate routers from the root to the destination.
	In this case, "1 <= ia <= m", m is the number of the intermediate		In this case, "1 <= ia <= m", m is the number of the intermediate
	routers (6LR).		routers (6LR).
	This scenario is the combination of the previous two cases.		This scenario is the combination of the previous two cases.
	The Figure 22 shows the table that summarizes what headers are needed		The Figure 24 shows the table that summarizes what headers are needed
	for this use case.		for this use case.
	+---------+------+-------+-------+---------+-------+---------+------+		+---------+------+-------+-------+---------+-------+---------+------+
	| Header | RUL | 6LR_1 | 6LR_ia| 6LBR |6LR_id | 6LR_m | RUL |		| Header | RUL | 6LR_1 | 6LR_ia| 6LBR |6LR_id | 6LR_m | RUL |
	| | src | | | | | | dst |		| | src | | | | | | dst |
	| | node | | | | | | node |		| | node | | | | | | node |
	+---------+------+-------+-------+---------+-------+---------+------+		+---------+------+-------+-------+---------+-------+---------+------+
	| Added | -- |IP6-IP6| -- | IP6-IP6 | -- | -- | -- |		| Added | -- |IP6-IP6| -- | IP6-IP6 | -- | -- | -- |
	| headers | | (RPI1)| | (RH3, | | | |		| headers | | (RPI1)| | (RH3, | | | |
	| | | | | RPI2) | | | |		| | | | | RPI2) | | | |
	skipping to change at page 44, line 48 ¶		skipping to change at page 47, line 48 ¶
	| | | | | | RPI2)| | |		| | | | | | RPI2)| | |
	+---------+------+-------+-------+---------+-------+---------+------+		+---------+------+-------+-------+---------+-------+---------+------+
	| Removed | -- | -- | -- | IP6-IP6 | -- | IP6-IP6 | -- |		| Removed | -- | -- | -- | IP6-IP6 | -- | IP6-IP6 | -- |
	| headers | | | | (RPI1) | | (RH3, | |		| headers | | | | (RPI1) | | (RH3, | |
	| | | | | | | RPI2) | |		| | | | | | | RPI2) | |
	+---------+------+-------+-------+---------+-------+---------+------+		+---------+------+-------+-------+---------+-------+---------+------+
	|Untouched| -- | -- | -- | -- | -- | -- | -- |		|Untouched| -- | -- | -- | -- | -- | -- | -- |
	| headers | | | | | | | |		| headers | | | | | | | |
	+---------+------+-------+-------+---------+-------+---------+------+		+---------+------+-------+-------+---------+-------+---------+------+
	Figure 22: Non-SM: Summary of the use of headers from RUL to RUL		Figure 24: Non-SM: Summary of the use of headers from RUL to RUL
	9. Operational Considerations of supporting RUL-leaves		9. Operational Considerations of supporting RUL-leaves
	Roughly half of the situations described in this document involve		Roughly half of the situations described in this document involve
	leaf ("host") nodes that do not speak RPL. These nodes fall into two		leaf ("host") nodes that do not speak RPL. These nodes fall into two
	further categories: ones that drop a packet that have RPI or RH3		further categories: ones that drop a packet that have RPI or RH3
	headers, and ones that continue to process a packet that has RPI and/		headers, and ones that continue to process a packet that has RPI and/
	or RH3 headers.		or RH3 headers.
	[RFC8200] provides for new rules that suggest that nodes that have		[RFC8200] provides for new rules that suggest that nodes that have
	skipping to change at page 46, line 43 ¶		skipping to change at page 49, line 43 ¶
	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.
	11. IANA Considerations		11. IANA Considerations
	This document updates the registration made in [RFC6553] Destination		This document updates the registration made in [RFC6553] Destination
	Options and Hop-by-Hop Options registry from 0x63 to 0x23 as shown in		Options and Hop-by-Hop Options registry from 0x63 to 0x23 as shown in
	Figure 23.		Figure 25.
	+-------+-------------------+------------------------+---------- -+		+-------+-------------------+------------------------+---------- -+
	| Hex | Binary Value | Description | Reference |		| Hex | Binary Value | Description | Reference |
	+ Value +-------------------+ + +		+ Value +-------------------+ + +
	| | act | chg | rest | | |		| | act | chg | rest | | |
	+-------+-----+-----+-------+------------------------+------------+		+-------+-----+-----+-------+------------------------+------------+
	| 0x23 | 00 | 1 | 00011 | RPL Option |[RFCXXXX](*)|		| 0x23 | 00 | 1 | 00011 | RPL Option |[RFCXXXX](*)|
	+-------+-----+-----+-------+------------------------+------------+		+-------+-----+-----+-------+------------------------+------------+
	| 0x63 | 01 | 1 | 00011 | RPL Option(DEPRECATED) | [RFC6553] |		| 0x63 | 01 | 1 | 00011 | RPL Option(DEPRECATED) | [RFC6553] |
	| | | | | |[RFCXXXX](*)|		| | | | | |[RFCXXXX](*)|
	+-------+-----+-----+-------+------------------------+------------+		+-------+-----+-----+-------+------------------------+------------+
	Figure 23: Option Type in RPL Option.(*)represents this document		Figure 25: Option Type in RPL Option.(*)represents this document
	DODAG Configuration option is updated as follows (Figure 24):		DODAG Configuration option is updated as follows (Figure 26):
	+------------+-----------------+---------------+		+------------+-----------------+---------------+
	| Bit number | Description | Reference |		| Bit number | Description | Reference |
	+------------+-----------------+---------------+		+------------+-----------------+---------------+
	| 3 | RPI 0x23 enable | This document |		| 3 | RPI 0x23 enable | This document |
	+------------+-----------------+---------------+		+------------+-----------------+---------------+
	Figure 24: DODAG Configuration Option Flag to indicate the RPI-flag-		Figure 26: DODAG Configuration Option Flag to indicate the RPI-flag-
	day.		day.
	12. Security Considerations		12. Security Considerations
	The security considerations covered in [RFC6553] and [RFC6554] apply		The security considerations covered in [RFC6553] and [RFC6554] apply
	when the packets are in the RPL Domain.		when the packets are in the RPL Domain.
	The IPv6-in-IPv6 mechanism described in this document is much more		The IPv6-in-IPv6 mechanism described in this document is much more
	limited than the general mechanism described in [RFC2473]. The		limited than the general mechanism described in [RFC2473]. The
	willingness of each node in the LLN to decapsulate packets and		willingness of each node in the LLN to decapsulate packets and
	skipping to change at page 52, line 39 ¶		skipping to change at page 55, line 39 ¶
	[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-13 (work in		Lossy Networks", draft-ietf-6lo-ap-nd-19 (work in
	progress), January 2020.		progress), February 2020.
	[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-13 (work		Backbone Router", draft-ietf-6lo-backbone-router-16 (work
	in progress), September 2019.		in progress), February 2020.
	[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-21 (work in progress), November 2019.		plane-22 (work in progress), February 2020.
	[I-D.ietf-anima-bootstrapping-keyinfra]		[I-D.ietf-anima-bootstrapping-keyinfra]
	Pritikin, M., Richardson, M., Eckert, T., Behringer, M.,		Pritikin, M., Richardson, M., Eckert, T., Behringer, M.,
	and K. Watsen, "Bootstrapping Remote Secure Key		and K. Watsen, "Bootstrapping Remote Secure Key
	Infrastructures (BRSKI)", draft-ietf-anima-bootstrapping-		Infrastructures (BRSKI)", draft-ietf-anima-bootstrapping-
	keyinfra-34 (work in progress), January 2020.		keyinfra-35 (work in progress), February 2020.
	[I-D.ietf-intarea-tunnels]		[I-D.ietf-intarea-tunnels]
	Touch, J. and M. Townsley, "IP Tunnels in the Internet		Touch, J. and M. Townsley, "IP Tunnels in the Internet
	Architecture", draft-ietf-intarea-tunnels-10 (work in		Architecture", draft-ietf-intarea-tunnels-10 (work in
	progress), September 2019.		progress), September 2019.
	[I-D.ietf-roll-unaware-leaves]		[I-D.ietf-roll-unaware-leaves]
	Thubert, P. and M. Richardson, "Routing for RPL Leaves",		Thubert, P. and M. Richardson, "Routing for RPL Leaves",
	draft-ietf-roll-unaware-leaves-08 (work in progress),		draft-ietf-roll-unaware-leaves-09 (work in progress),
	December 2019.		January 2020.
	[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6		[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
	(IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460,		(IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460,
	December 1998, <https://www.rfc-editor.org/info/rfc2460>.		December 1998, <https://www.rfc-editor.org/info/rfc2460>.
	[RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in		[RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in
	IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473,		IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473,
	December 1998, <https://www.rfc-editor.org/info/rfc2473>.		December 1998, <https://www.rfc-editor.org/info/rfc2473>.
	[RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet		[RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet
	skipping to change at page 54, line 40 ¶		skipping to change at page 57, line 40 ¶
	May 2017, <https://www.rfc-editor.org/info/rfc8180>.		May 2017, <https://www.rfc-editor.org/info/rfc8180>.
	[RFC8505] Thubert, P., Ed., Nordmark, E., Chakrabarti, S., and C.		[RFC8505] Thubert, P., Ed., Nordmark, E., Chakrabarti, S., and C.
	Perkins, "Registration Extensions for IPv6 over Low-Power		Perkins, "Registration Extensions for IPv6 over Low-Power
	Wireless Personal Area Network (6LoWPAN) Neighbor		Wireless Personal Area Network (6LoWPAN) Neighbor
	Discovery", RFC 8505, DOI 10.17487/RFC8505, November 2018,		Discovery", RFC 8505, DOI 10.17487/RFC8505, November 2018,
	<https://www.rfc-editor.org/info/rfc8505>.		<https://www.rfc-editor.org/info/rfc8505>.
	Authors' Addresses		Authors' Addresses
	Maria Ines Robles		Maria Ines Robles
	Aalto University, Finland/Uni. Tec. Nac.(UTN) - FRM, Argentina		Universidad Tecno. Nac.(UTN)-FRM, Argentina / Aalto University, Finland
	Email: mariainesrobles@gmail.com		Email: mariainesrobles@gmail.com
	Michael C. Richardson		Michael C. Richardson
	Sandelman Software Works		Sandelman Software Works
	470 Dawson Avenue		470 Dawson Avenue
	Ottawa, ON K1Z 5V7		Ottawa, ON K1Z 5V7
	CA		CA
	Email: mcr+ietf@sandelman.ca		Email: mcr+ietf@sandelman.ca
	URI: http://www.sandelman.ca/mcr/		URI: http://www.sandelman.ca/mcr/
	Pascal Thubert		Pascal Thubert
End of changes. 54 change blocks.
	214 lines changed or deleted		307 lines changed or added
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