< draft-ietf-roll-useofrplinfo-05.txt		draft-ietf-roll-useofrplinfo-06.txt >
	ROLL Working Group M. Robles		ROLL Working Group M. Robles
	Internet-Draft Ericsson		Internet-Draft Ericsson
	Intended status: Informational M. Richardson		Intended status: Informational M. Richardson
	Expires: December 12, 2016 SSW		Expires: January 19, 2017 SSW
	P. Thubert		P. Thubert
	Cisco		Cisco
	June 10, 2016		July 18, 2016
	When to use RFC 6553, 6554 and IPv6-in-IPv6		When to use RFC 6553, 6554 and IPv6-in-IPv6
	draft-ietf-roll-useofrplinfo-05		draft-ietf-roll-useofrplinfo-06
	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, RFC 6554 and IPv6-in-IPv6		enumerates the cases where RFC 6553, RFC 6554 and IPv6-in-IPv6
	encapsulation is required. This analysis provides the basis on which		encapsulation is required. This analysis provides the basis on which
	to design efficient compression of these headers.		to design efficient compression of these headers.
	skipping to change at page 1, line 38 ¶		skipping to change at page 1, line 38 ¶
	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 http://datatracker.ietf.org/drafts/current/.		Drafts is at http://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 December 12, 2016.		This Internet-Draft will expire on January 19, 2017.
	Copyright Notice		Copyright Notice
	Copyright (c) 2016 IETF Trust and the persons identified as the		Copyright (c) 2016 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
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	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
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	described in the Simplified BSD License.		described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
	2. Terminology and Requirements Language . . . . . . . . . . . . 3		2. Terminology and Requirements Language . . . . . . . . . . . . 3
			2.1. hop-by-hop IPv6-in-IPv6 headers . . . . . . . . . . . . . 4
	3. Sample/reference topology . . . . . . . . . . . . . . . . . . 4		3. Sample/reference topology . . . . . . . . . . . . . . . . . . 4
	4. Use cases . . . . . . . . . . . . . . . . . . . . . . . . . . 6		4. Use cases . . . . . . . . . . . . . . . . . . . . . . . . . . 7
	5. Storing mode . . . . . . . . . . . . . . . . . . . . . . . . 8		5. Storing mode . . . . . . . . . . . . . . . . . . . . . . . . 8
	5.1. Example of Flow from RPL-aware-leaf to root . . . . . . . 9		5.1. Example of Flow from RPL-aware-leaf to root . . . . . . . 9
	5.2. Example of Flow from root to RPL-aware-leaf . . . . . . . 10		5.2. Example of Flow from root to RPL-aware-leaf . . . . . . . 10
	5.3. Example of Flow from root to not-RPL-aware-leaf . . . . . 11		5.3. Example of Flow from root to not-RPL-aware-leaf . . . . . 11
	5.4. Example of Flow from not-RPL-aware-leaf to root . . . . . 11		5.4. Example of Flow from not-RPL-aware-leaf to root . . . . . 12
	5.5. Example of Flow from RPL-aware-leaf to Internet . . . . . 12		5.5. Example of Flow from RPL-aware-leaf to Internet . . . . . 12
	5.6. Example of Flow from Internet to RPL-aware-leaf . . . . . 13		5.6. Example of Flow from Internet to RPL-aware-leaf . . . . . 13
	5.7. Example of Flow from not-RPL-aware-leaf to Internet . . . 13		5.7. Example of Flow from not-RPL-aware-leaf to Internet . . . 14
	5.8. Example of Flow from Internet to non-RPL-aware-leaf . . . 14		5.8. Example of Flow from Internet to non-RPL-aware-leaf . . . 14
	5.9. Example of Flow from RPL-aware-leaf to RPL-aware-leaf . . 15		5.9. Example of Flow from RPL-aware-leaf to RPL-aware-leaf . . 15
	5.10. Example of Flow from RPL-aware-leaf to non-RPL-aware-leaf 16		5.10. Example of Flow from RPL-aware-leaf to non-RPL-aware-leaf 16
	5.11. Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf 17		5.11. Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf 18
	5.12. Example of Flow from not-RPL-aware-leaf to not-RPL-aware-		5.12. Example of Flow from not-RPL-aware-leaf to not-RPL-aware-
	leaf . . . . . . . . . . . . . . . . . . . . . . . . . . 18		leaf . . . . . . . . . . . . . . . . . . . . . . . . . . 19
	6. Non Storing mode . . . . . . . . . . . . . . . . . . . . . . 19		6. Non Storing mode . . . . . . . . . . . . . . . . . . . . . . 20
	6.1. Example of Flow from RPL-aware-leaf to root . . . . . . . 19		6.1. Example of Flow from RPL-aware-leaf to root . . . . . . . 20
	6.2. Example of Flow from root to RPL-aware-leaf . . . . . . . 20		6.2. Example of Flow from root to RPL-aware-leaf . . . . . . . 21
	6.3. Example of Flow from root to not-RPL-aware-leaf . . . . . 20		6.3. Example of Flow from root to not-RPL-aware-leaf . . . . . 21
	6.4. Example of Flow from not-RPL-aware-leaf to root . . . . . 21		6.4. Example of Flow from not-RPL-aware-leaf to root . . . . . 22
	6.5. Example of Flow from RPL-aware-leaf to Internet . . . . . 22		6.5. Example of Flow from RPL-aware-leaf to Internet . . . . . 23
	6.6. Example of Flow from Internet to RPL-aware-leaf . . . . . 22		6.6. Example of Flow from Internet to RPL-aware-leaf . . . . . 23
	6.7. Example of Flow from not-RPL-aware-leaf to Internet . . . 23		6.7. Example of Flow from not-RPL-aware-leaf to Internet . . . 24
	6.8. Example of Flow from Internet to non-RPL-aware-leaf . . . 24		6.8. Example of Flow from Internet to non-RPL-aware-leaf . . . 25
	6.9. Example of Flow from RPL-aware-leaf to RPL-aware-leaf . . 24		6.9. Example of Flow from RPL-aware-leaf to RPL-aware-leaf . . 25
	6.10. Example of Flow from RPL-aware-leaf to not-RPL-aware-leaf 25		6.10. Example of Flow from RPL-aware-leaf to not-RPL-aware-leaf 26
	6.11. Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf 26		6.11. Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf 27
	6.12. Example of Flow from not-RPL-aware-leaf to not-RPL-aware-		6.12. Example of Flow from not-RPL-aware-leaf to not-RPL-aware-
	leaf . . . . . . . . . . . . . . . . . . . . . . . . . . 27		leaf . . . . . . . . . . . . . . . . . . . . . . . . . . 28
	7. Observations about the problem . . . . . . . . . . . . . . . 27		7. Observations about the problem . . . . . . . . . . . . . . . 28
	7.1. Storing mode . . . . . . . . . . . . . . . . . . . . . . 27		7.1. Storing mode . . . . . . . . . . . . . . . . . . . . . . 28
	7.2. Non-Storing mode . . . . . . . . . . . . . . . . . . . . 28		7.2. Non-Storing mode . . . . . . . . . . . . . . . . . . . . 29
	8. 6LoRH Compression cases . . . . . . . . . . . . . . . . . . . 29		8. 6LoRH Compression cases . . . . . . . . . . . . . . . . . . . 30
	9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29		9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 30
	10. Security Considerations . . . . . . . . . . . . . . . . . . . 29		10. Security Considerations . . . . . . . . . . . . . . . . . . . 30
	11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 29		11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 30
	12. References . . . . . . . . . . . . . . . . . . . . . . . . . 29		12. References . . . . . . . . . . . . . . . . . . . . . . . . . 30
	12.1. Normative References . . . . . . . . . . . . . . . . . . 29		12.1. Normative References . . . . . . . . . . . . . . . . . . 30
	12.2. Informative References . . . . . . . . . . . . . . . . . 30		12.2. Informative References . . . . . . . . . . . . . . . . . 31
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 31		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 32
	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.
	skipping to change at page 3, line 35 ¶		skipping to change at page 3, line 36 ¶
	artifacts as possible that not all implementors agree when artifacts		artifacts as possible that not all implementors 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		An interim meeting went through the 24 cases defined here to discover
	if there were any shortcuts, and this document is the result of that		if there were any shortcuts, and this document is the result of that
	discussion. This document should not be defining anything new, but		discussion. This document should not be defining anything new, but
	it may clarify what is correct and incorrect behaviour.		it may clarify what is correct and incorrect behaviour.
	The related document A Routing Header Dispatch for 6LoWPAN (6LoRH)		The related document A Routing Header Dispatch for 6LoWPAN (6LoRH)
	[I-D.ietf-roll-routing-dispatch] defines a method to compress RPL		[I-D.ietf-roll-routing-dispatch] defines a method to compress RPL
	Option information and Routing Header type 3 (RFC6554) and an		Option information and Routing Header type 3 [RFC6554], an efficient
	efficient IP-in-IP technique. Uses cases proposed for the		IP-in-IP technique, and use cases proposed for the
	[Second6TischPlugtest] involving 6loRH.		[Second6TischPlugtest] involving 6loRH.
	2. Terminology and Requirements Language		2. Terminology and Requirements Language
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this		"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
	document are to be interpreted as described in RFC 2119 [RFC2119].		document are to be interpreted as described in RFC 2119 [RFC2119].
	Terminology defined in [RFC7102] applies to this document: LBR, LLN,		Terminology defined in [RFC7102] applies to this document: LBR, LLN,
	RPL, RPL Domain and ROLL.		RPL, RPL Domain and ROLL.
			2.1. hop-by-hop IPv6-in-IPv6 headers
			The term "hop-by-hop IPv6-in-IPv6" 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 use the link-local addresses) of
			each node. If the packet must traverse multiple hops, then it must
			be decapsulated at each hop, and then re-encapsulated again in a
			similar fashion.
	3. Sample/reference topology		3. Sample/reference topology
	A RPL network is composed of a 6LBR (6LoWPAN Border Router), Backbone		A RPL network is composed of a 6LBR (6LoWPAN Border Router), Backbone
	Router (6BBR), 6LR (6LoWPAN Router) and 6LN (6LoWPAN Node) as leaf		Router (6BBR), 6LR (6LoWPAN Router) and 6LN (6LoWPAN Node) as leaf
	logically organized in a DODAG structure (Destination Oriented		logically organized in a DODAG structure (Destination Oriented
	Directed Acyclic Graph).		Directed Acyclic Graph).
	RPL defines the RPL Control messages (control plane), a new ICMPv6		RPL defines the RPL Control messages (control plane), a new ICMPv6
	[RFC4443] message with Type 155. DIS (DODAG Information		[RFC4443] message with Type 155. DIS (DODAG Information
	Solicitation), DIO (DODAG Information Object) and DAO (Destination		Solicitation), DIO (DODAG Information Object) and DAO (Destination
	Advertisement Object) messages are all RPL Control messages but with		Advertisement Object) messages are all RPL Control messages but with
	different Code values.		different Code values. A RPL Stack is showed in Figure 1.
	RPL supports two modes of Downward traffic: in storing mode (RPL-SM),		RPL supports two modes of Downward traffic: in storing mode (RPL-SM),
	it is fully stateful or an in non-storing (RPL-NSM), it is fully		it is fully stateful or an in non-storing (RPL-NSM), it is fully
	source routed. A RPL Instance is either fully storing or fully non-		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, i.e. a RPL Instance with a combination of storing and non-
	storing nodes is not supported with the current specifications at the		storing nodes is not supported with the current specifications at the
	time of writing this document.		time of writing this document.
	+--------------+		+--------------+
	| Upper Layers |		| Upper Layers |
	skipping to change at page 5, line 33 ¶		skipping to change at page 6, line 33 ¶
	| | | | |		| | | | |
	| | | | |		| | | | |
	| 21 | 22 | 23 | 24 | 25		| 21 | 22 | 23 | 24 | 25
	+-+---+ +-+---+ +--+--+ +- --+ +---+-+		+-+---+ +-+---+ +--+--+ +- --+ +---+-+
	|Leaf | | | | | |Leaf| |Leaf |		|Leaf | | | | | |Leaf| |Leaf |
	| 6LN | | | | | | 6LN| | 6LN |		| 6LN | | | | | | 6LN| | 6LN |
	+-----+ +-----+ +-----+ +----+ +-----+		+-----+ +-----+ +-----+ +----+ +-----+
	Figure 2: A reference RPL Topology.		Figure 2: A reference RPL Topology.
			In Figure 2 is showed the reference RPL Topology for this document.
	The numbers in or above the nodes are there so that they may be		The numbers in or above the nodes are there so that they may be
	referenced in subsequent sections. In the figure 2, 6LN can be a		referenced in subsequent sections. In the figure, a 6LN can be a
	router or a host. The 6LN leaf marked as (21) and (25) are routers.		router or a host. The 6LN leafs marked as (21) and (25) are routers.
	The leaf marked 6LN (24) is a device which does not speak RPL at all		The leaf marked 6LN (24) is a device which does not speak RPL at all
	(not-RPL-aware), but uses Router-Advertisements, 6LowPAN DAR/DAC and		(not-RPL-aware), but uses Router-Advertisements, 6LowPAN DAR/DAC and
	efficient-ND only to participate in the network [RFC6775]. In the		efficient-ND only to participate in the network [RFC6775]. In the
	document this leaf (24) is mentioned as well as IPv6 node. The 6LBR		document this leaf (24) is often named IPv6 node. The 6LBR in the
	in the figure is the root of the Global DODAG.		figure is the root of the Global DODAG.
	This document is in part motivated by the work that is ongoing at the		This document is in part motivated by the work that is ongoing at the
	6TiSCH working group. The 6TiSCH architecture		6TiSCH working group. The 6TiSCH architecture
	[I-D.ietf-6tisch-architecture] draft explains the network		[I-D.ietf-6tisch-architecture] draft explains the network
	architecture of a 6TiSCH network. This architecture is used for the		architecture of a 6TiSCH network.
	remainder of this document.
	The scope of the 6TiSCH (IPv6 over the TSCH mode of IEEE 802.15.4e)
	Architecture is a Backbone Link that federates multiple LLNs (mesh)
	as a single IPv6 Multi-Link Subnet. Each LLN in the subnet is
	anchored at a Backbone Router (6BBR). The Backbone Routers
	interconnect the LLNs over the Backbone Link and emulate that the LLN
	nodes are present on the Backbone thus creating a so-called: Multi-
	Link Subnet. An LLN node can move freely from an LLN anchored at a
	Backbone Router to another LLN anchored at the same or a different
	Backbone Router inside the Multi-Link Subnet and conserve its
	addresses. Internet is connected through the 6BBR. For the
	following uses cases the 6BBR would be mapped to 6LBR and the
	Backbone router to 6LR.
	+---------+
	+---+Internet |
	| +---------+
	|
	|
	+-----+
	| | Border Router to the RPL domain
	| | (may be a RPL virtual root)
	+-----+
	|
	| Backbone
	+-------------------+-------------------+
	| | |
	+-----+ +-----+ +-----+
	| | Backbone | | Backbone | | Backbone
	| | router | | router | | router
	+|---|+ +-|||-+ +-[_]-+
	| | PCI-exp / | \ USB | Ethernet
	( ) ( ) ( )( )( ) (6LBR == RPL DODAG root)
	o o o o o o o o o o o o
	o o o o o o o o o o o o o o o o
	o o o o o o o o o o 6LR == RPL router) o o
	o o o o o o o z
	o o o o o o (6LoWPAN Host)
	<----------------------- RPL Instances ------------------------>
	Figure 3: RPL domain architecture
	4. Use cases		4. Use cases
	In data plane context a combination of RFC6553, RFC6554 and IPv6-in-		In data plane context a combination of RFC6553, RFC6554 and IPv6-in-
	IPv6 encapsulation is going to be analyzed for the following traffic		IPv6 encapsulation is going to be analyzed for the following traffic
	flows:		flows:
	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
	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 7, line 27 ¶		skipping to change at page 7, line 36 ¶
	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
	not-RPL-aware-leaf to RPL-aware-leaf		not-RPL-aware-leaf to RPL-aware-leaf
	not-RPL-aware-leaf to not-RPL-aware-leaf		not-RPL-aware-leaf to not-RPL-aware-leaf
	This document assumes a rule that a Header cannot be inserted or		This document assumes a rule that a Header cannot be inserted or
	removed on the fly inside an IPv6 packet that is being routed. This		removed on the fly inside an IPv6 packet that is being routed. A
	is a fundamental precept of the IPv6 architecture as outlined in		fundamental precept of the IPv6 architecture as outlined in [RFC2460]
	[RFC2460] is that Extensions may not be added or removed except by		is that Extensions may not be added or removed except by the sender
	the sender or the receiver.		or the receiver.
	Note: current discussions on [I-D.ietf-6man-rfc2460bis] related to		Note: current discussions on [I-D.ietf-6man-rfc2460bis] related to
	extensions headers may affect some cases in this document (Ticket		extensions headers may affect some cases in this document (Ticket
	nro. 9) in 6man. [TO DO].		nro. 9) in 6man. [TO DO].
	A second important thing is that packets with a Hop-by-Hop option		A second important thing is that packets with a Hop-by-Hop option
	which are marked with option type 01 ([RFC2460] section 4.2) must be		which are marked with option type 01 ([RFC2460] section 4.2) must be
	discarded if received by a host or router which does not understand		discarded if received by a host or router which does not understand
	that option. This means that in general, any packet that leaves the		that option. This means that in general, any packet that leaves the
	RPL domain of an LLN (or leaves the LLN entirely) is likely to be		RPL domain of an LLN (or leaves the LLN entirely) is likely to be
	skipping to change at page 8, line 13 ¶		skipping to change at page 8, line 21 ¶
	can be placed.		can be placed.
	This also means that a Header can only be removed by an intermediate		This also means that a Header can only be removed by an intermediate
	router if it is placed in an encapsulating IPv6 Header, and in that		router if it is placed in an encapsulating IPv6 Header, and in that
	case, the whole encapsulating header must be removed - a replacement		case, the whole encapsulating header must be removed - a replacement
	may be added. Further, an intermediate router can only remove such		may be added. Further, an intermediate router can only remove such
	an outer header if that outer header has the router as the		an outer header if that outer header has the router as the
	destination!		destination!
	Both RPI and RH3 headers may be modified by routers on the path of		Both RPI and RH3 headers may be modified by routers on the path of
	the packet without the need to add to remove an encapsulating header.		the packet without the need to add or remove an encapsulating header.
	Both headers were designed with this modification in mind, and both		Both headers were designed with this modification in mind, and both
	the RPL RH and the RPL option are marked mutable but recoverable, so		the RPL RH and the RPL option are marked mutable but recoverable, so
	an IPsec AH security header can be applied across these headers, but		an IPsec AH security header can be applied across these headers, but
	it may not secure all the values in those headers.		it may not secure all the values in those headers.
	RPI should be present in every single RPL data packet. There is one		RPI should be present in every single RPL data packet. There is one
	exception in non-storing mode: when a packet is going down from the		exception in non-storing mode: when a packet is going down from the
	root. In a downward non-storing mode, the entire route is written,		root. In a downward non-storing mode, the entire route is written,
	so there can be no loops by construction, nor any confusion about		so there can be no loops by construction, nor any confusion about
	which forwarding table to use. There may be cases (such as in		which forwarding table to use. There may be cases (such as in
	6tisch) where the instanceID may still be needed to pick an		6tisch) where the instanceID may still be needed to pick an
	appropriate priority or channel at each hop.		appropriate priority or channel at each hop.
	The applicability for storing (RPL-SM) and non-Storing (RPL-NSM)		The applicability for storing (RPL-SM) and non-Storing (RPL-NSM)
	modes for the previous cases is showed as follows:		modes for the previous cases is showed as follows:
	In tables, the term "RPL aware leaf" is has been shortened to "Raf",		In the tables present in this document, the term "RPL aware leaf" is
	and "not-RPL aware leaf" has been shortened to "~Raf" to make the		has been shortened to "Raf", and "not-RPL aware leaf" has been
	table fit in available space.		shortened to "~Raf" to make the table fit in available space.
	The earlier examples are more complete 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 consise.		is clear, while later examples are more consise.
	5. Storing mode		5. Storing mode
	In storing mode (fully stateful), determinate whether the destination		In storing mode (fully stateful), the sender cannot determine whether
	is RPL capable is not currently discernible by the sender and thus		the destination is RPL-capable and thus would need an IP-in-IP
	would need an IP-in-IP header. The IP-in-IP header needs to be		header. The IP-in-IP header needs to be addressed on a hop-by-hop
	addressed on a hop-by-hop basis so that the last 6LR can remove the		basis so that the last 6LR can remove the RPI header. Additionally,
	RPI header. Additionally, The sender can determine if the		The sender can determine if the destination is inside the LLN by
	destination is inside the LLN by looking if the destination address		looking if the destination address is matched by the DIO's PIO
	is matched by the DIO's PIO option.		option.
	The following table summarizes what headers are needed in the		The following table summarizes what headers are needed in the
	following scenarios, and indicates the IP-in-IP header must be		following scenarios, and indicates when the IP-in-IP header must be
	inserted on a hop-by-hop basis, and when it can target the		inserted on a hop-by-hop basis, and when it can target the
	destination node directly. There are three possible situations: hop-		destination node directly. There are three possible situations: hop-
	by-hop necessary (indicated by "hop"), or destination address		by-hop necessary (indicated by "hop"), or destination address
	possible (indicated by "dst"). In all cases hop by hop can be used.		possible (indicated by "dst"). In all cases hop by hop can be used.
	In cases where no IP-in-IP header is needed, the column is left		In cases where no IP-in-IP header is needed, the column is left
	blank.		blank.
	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.
	+--------------+-------+-------+-----------+---------------+		+--------------+-------+-------+-----------+---------------+
	| Use Case | RPI | RH3 | IP-in-IP | IP-in-IP dst |		| Use Case | RPI | RH3 | IP-in-IP | IP-in-IP dst |
	+--------------+-------+-------+-----------+---------------+		+--------------+-------+-------+-----------+---------------+
	| Raf to root | Yes | No | No | -- |		| Raf to root | Yes | No | No | -- |
	| root to Raf | Yes | No | No | -- |		| root to Raf | Yes | No | No | -- |
	skipping to change at page 9, line 50 ¶		skipping to change at page 10, line 10 ¶
	messages.		messages.
	In storing mode, RFC 6553 (RPI) is used to send RPL Information		In storing mode, RFC 6553 (RPI) is used to send RPL Information
	instanceID and rank information.		instanceID and rank information.
	In this case the flow comprises:		In this case the flow comprises:
	RPL-aware-leaf (6LN) --> 6LR --> 6LR,... --> root (6LBR)		RPL-aware-leaf (6LN) --> 6LR --> 6LR,... --> 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-
	fledge RPL routers, and are the RPL root node.		fledge RPL routers.
	The 6LN inserts the RPI header, and sends the packet to 6LR which		The 6LN inserts the RPI header, and sends the packet to 6LR which
	decrements the rank in RPI and sends the packet up. When the packet		decrements the rank in RPI and sends the packet up. When the packet
	arrives at 6LBR, the RPI is removed and the packet is processed.		arrives at 6LBR, the RPI is removed and the packet is processed.
	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 in order to be able to make use of this scenario. The		with the 6LBR to make use of this scenario. The 6LN can know the
	6LN can know the address of the 6LBR because it knows the address of		address of the 6LBR because it knows the address of the root via the
	the root via the DODAGID in the DIO messages.		DODAGID in the DIO messages.
	+-------------------+-----+------+------+		+-------------------+-----+------+------+
	| Header | 6LN | 6LR | 6LBR |		| Header | 6LN | 6LR | 6LBR |
	+-------------------+-----+------+------+		+-------------------+-----+------+------+
	| 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 | -- | -- | -- |
	+-------------------+-----+------+------+		+-------------------+-----+------+------+
	Storing: Summary of the use of headers from RPL-aware-leaf to root		Storing: Summary of the use of headers from RPL-aware-leaf to root
	5.2. Example of Flow from root to RPL-aware-leaf		5.2. Example of Flow from root to RPL-aware-leaf
	In this case the flow comprises:		In this case the flow comprises:
	root (6LBR)--> 6LR --> RPL-aware-leaf (6LN)		root (6LBR)--> 6LR --> RPL-aware-leaf (6LN)
	In this case the 6LBR insert RPI header and send the packet down, the		In this case the 6LBR inserts RPI header and sends the packet down,
	6LR is going to increment the rank in RPI (examines instanceID for		the 6LR is going to increment the rank in RPI (examines instanceID
	multiple tables), the packet is processed in 6LN and RPI removed.		for multiple tables), the packet is processed in 6LN and RPI removed.
	No IP-in-IP header is required.		No IP-in-IP header is required.
	+-------------------+------+-------+------+		+-------------------+------+-------+------+
	| Header | 6LBR | 6LR | 6LN |		| Header | 6LBR | 6LR | 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 | -- |
	skipping to change at page 15, line 21 ¶		skipping to change at page 15, line 38 ¶
	In this case the flow comprises:		In this case the flow comprises:
	6LN --> 6LR --> common parent (6LR) --> 6LR --> 6LN		6LN --> 6LR --> common parent (6LR) --> 6LR --> 6LN
	This case is assumed in the same RPL Domain. In the common parent,		This case is assumed in the same RPL Domain. In the common parent,
	the direction of RPI is changed (from increasing to decreasing the		the direction of RPI is changed (from increasing to decreasing the
	rank).		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 IP-in-IP headers are necessary. The ability to		remove the RPI, so no IP-in-IP headers are necessary. The ability to
	do this depends upon the sending know that the destination is: a)		do this depends upon the sending the 6LN to know that the destination
	inside the LLN, and b) RPL capable.		is: a) inside the LLN, and b) RPL capable.
	The sender can determine if the destination is inside the LLN by		The sender can determine if the destination is inside the LLN by
	looking if the destination address is matched by the DIO's PIO		looking if the destination address is matched by the DIO's PIO
	option. This check may be modified by the use of backbone routers,		option. This check may be modified by the use of backbone routers,
	but in this case it is assumed that the backbone routers are RPL		but in this case it is assumed that the backbone routers are RPL
	capable and so can process the RPI header correctly.		capable and so can process the RPI header correctly.
	The other check, that the destination is RPL capable is not currently		The other check, that the destination is RPL capable is not currently
	discernible by the sender. This information is necessary to		discernible by the sender. This information is necessary to
	distinguish this test case from Section 5.10.		distinguish this test case from Section 5.10.
	skipping to change at page 16, line 12 ¶		skipping to change at page 16, line 32 ¶
	Storing: Summary of the use of headers for RPL-aware-leaf to RPL-		Storing: Summary of the use of headers for RPL-aware-leaf to RPL-
	aware-leaf		aware-leaf
	5.10. Example of Flow from RPL-aware-leaf to non-RPL-aware-leaf		5.10. Example of Flow from RPL-aware-leaf to non-RPL-aware-leaf
	In this case the flow comprises:		In this case the flow comprises:
	6LN --> 6LR --> common parent (6LR) --> 6LR --> not-RPL-aware 6LN		6LN --> 6LR --> common parent (6LR) --> 6LR --> not-RPL-aware 6LN
	The sender, being aware out of band, that the receiver is not RPL		The sender, being aware out of band, that the receiver is not RPL
	aware, sends adds an RPI header inside an IP-in-IP header. The IP-		aware, adds an RPI header inside an IP-in-IP header. The IP-in-IP
	in-IP header needs to be addressed on a hop-by-hop basis so that the		header needs to be addressed on a hop-by-hop basis so that the last
	last 6LR can remove the RPI header.		6LR can remove the RPI header.
	,---.		,---.
	/ \		/ \
	( 6LR2 ) IP3,RPI,IP,ULP		( 6LR2 ) IP3,RPI,IP,ULP
	,-" .		,-" .
	,-" `---' `.		,-" `---' `.
	,' `.		,' `.
	,---. ,-" `,---.		,---. ,-" `,---.
	/ +" / \		/ +" / \
	( 6LR1 ) Remove the IP3,RPI( 6LR3 )		( 6LR1 ) Remove the IP3,RPI( 6LR3 )
	skipping to change at page 16, line 37 ¶		skipping to change at page 17, line 26 ¶
	/ IP2,RPI,IP,ULP \		/ IP2,RPI,IP,ULP \
	/ |		/ |
	/ \		/ \
	,---+-. |		,---+-. |
	/ \ +--+----+		/ \ +--+----+
	( 6LN ) | |		( 6LN ) | |
	\ / | IPv6 | IP,ULP		\ / | IPv6 | IP,ULP
	`-----' | |		`-----' | |
	IP1,RPI,IP,ULP +-------+		IP1,RPI,IP,ULP +-------+
	Figure 4: Solution IPv6-in-IPv6 in each hop		Figure 3: Solution IPv6-in-IPv6 in each hop
	Alternatively, if the definition of the Option Type field of RPL		As we mentioned previously, packets with a Hop-by-Hop option which
	Option '01' were changed so that it isn't a "discard if not		are marked with option type 01 ([RFC2460] section 4.2) must be
	recognized", then no IP-in-IP header would be necessary. This change		discarded if received by a host or router which does not understand
	is an incompatible on-the-wire change and would require some kind of		that option. This means that in general, any packet that leaves the
	flag day, possibly a change that is done simultaenously with an		RPL domain of an LLN (or leaves the LLN entirely) is likely to be
	updated 6LoRH compress.		discarded if it still contains an [RFC6553] RPL Option Header known
			as the RPI. For this case, if the definition of the Option Type
			field of RPL Option '01' were changed so that it isn't a "discard if
			not recognized", then no IP-in-IP header would be necessary. This
			change is an incompatible on-the-wire change and would require some
			kind of flag day, possibly a change that is done simultaenously with
			an updated 6LoRH compress.
	+--------+------------+------------+------------+------------+------+		+--------+------------+------------+------------+------------+------+
	| Header | 6LN | 6LR | 6LR | 6LR | IPv6 |		| Header | 6LN | 6LR | 6LR | 6LR | IPv6 |
	| | | | (common | | |		| | | | (common | | |
	| | | | parent) | | |		| | | | parent) | | |
	+--------+------------+------------+------------+------------+------+		+--------+------------+------------+------------+------------+------+
	| Insert | IP-in- | -- | -- | -- | -- |		| Insert | IP-in- | -- | -- | -- | -- |
	| ed hea | IP(RPI) | | | | |		| ed hea | IP(RPI) | | | | |
	| ders | | | | | |		| ders | | | | | |
	| Remove | -- | -- | -- | IP-in- | -- |		| Remove | -- | -- | -- | IP-in- | -- |
	skipping to change at page 17, line 39 ¶		skipping to change at page 18, line 39 ¶
	RPL-aware-leaf		RPL-aware-leaf
	5.11. Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf		5.11. 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 --> 6LR --> common parent (6LR) --> 6LR --> 6LN		not-RPL-aware 6LN --> 6LR --> common parent (6LR) --> 6LR --> 6LN
	The 6LR receives the packet from the the IPv6 node and inserts and		The 6LR receives the packet from the the IPv6 node and inserts and
	the RPI header encapsulated in IPv6-in-IPv6 header. The IP-in-IP		the RPI header encapsulated in IPv6-in-IPv6 header. The IP-in-IP
	header could be addresses to the 6LN if the destination is known to		header could be addressed to the 6LN if the destination is known to
	the RPL aware, otherwise must send the packet using a hop-by-hop IP-		the RPL aware, otherwise it must send the packet using a hop-by-hop
	in-IP header. Similar considerations apply from section		IP-in-IP header. Similar considerations apply from section
	Section 5.10.		Section 5.10.
	+--------+------+------------+------------+------------+------------+		+--------+------+------------+------------+------------+------------+
	| Header | IPv6 | 6LR | common | 6LR | 6LN |		| Header | IPv6 | 6LR | common | 6LR | 6LN |
	| | | | parent | | |		| | | | parent | | |
	| | | | (6LR) | | |		| | | | (6LR) | | |
	+--------+------+------------+------------+------------+------------+		+--------+------+------------+------------+------------+------------+
	| Insert | -- | IP-in- | -- | -- | -- |		| Insert | -- | IP-in- | -- | -- | -- |
	| ed hea | | IP(RPI) | | | |		| ed hea | | IP(RPI) | | | |
	| ders | | | | | |		| ders | | | | | |
	skipping to change at page 19, line 5 ¶		skipping to change at page 20, line 5 ¶
	In this case the flow comprises:		In this case the flow comprises:
	not-RPL-aware 6LN (IPv6 node)--> 6LR --> root (6LBR) --> 6LR --> not-		not-RPL-aware 6LN (IPv6 node)--> 6LR --> root (6LBR) --> 6LR --> not-
	RPL-aware 6LN (IPv6 node)		RPL-aware 6LN (IPv6 node)
	This flow combines the problems of the two previous sections. There		This flow combines the problems of the two previous sections. There
	is no choice at the first 6LR: it must insert an RPI, and to do that		is no choice at the first 6LR: it must insert an RPI, and to do that
	it must add an IP-in-IP header. That IP-in-IP header must be		it must add an IP-in-IP header. That IP-in-IP header must be
	addressed on a hop-by-hop basis.		addressed on a hop-by-hop basis.
	+-----------+------+---------------+---------+---------------+------+		+----------+-----+-------------+--------------+--------------+------+
	| Header | IPv6 | 6LR | 6LR | 6LR | IPv6 |		| Header | IPv | 6LR | 6LR (common | 6LR | IPv6 |
	| | src | | (common | | dst |		| | 6 | | parent) | | dst |
	| | | | parent) | | |		| | src | | | | |
	+-----------+------+---------------+---------+---------------+------+		+----------+-----+-------------+--------------+--------------+------+
	| Inserted | -- | IP-in-IP(RPI) | -- | -- | -- |		| Inserted | -- | IP-in- | -- | -- | -- |
	| headers | | | | | |		| headers | | IP(RPI) | | | |
	| Removed | -- | -- | -- | IP-in-IP(RPI) | -- |		| Removed | -- | -- | -- | IP-in- | -- |
	| headers | | | | | |		| headers | | | | IP(RPI) | |
	| Re-added | -- | -- | -- | -- | -- |		| Re-added | -- | IP-in- | IP-in- | IP-in- | -- |
	| headers | | | | | |		| headers | | IP(RPI) | IP(RPI) | IP(RPI) | |
	| Modified | -- | -- | -- | -- | -- |		| Modified | -- | -- | -- | -- | -- |
	| headers | | | | | |		| headers | | | | | |
	| Untouched | -- | -- | -- | -- | -- |		| Untouche | -- | -- | -- | -- | -- |
	| headers | | | | | |		| d | | | | | |
	+-----------+------+---------------+---------+---------------+------+		| headers | | | | | |
			+----------+-----+-------------+--------------+--------------+------+
	Storing: Summary of the use of headers from not-RPL-aware-leaf to		Storing: Summary of the use of headers from not-RPL-aware-leaf to
	not-RPL-aware-leaf		not-RPL-aware-leaf
	6. Non Storing mode		6. Non Storing mode
	+--------------+------+------+-----------+---------------+		+--------------+------+------+-----------+---------------+
	| Use Case | RPI | RH3 | IP-in-IP | IP-in-IP dst |		| Use Case | RPI | RH3 | IP-in-IP | IP-in-IP dst |
	+--------------+------+------+-----------+---------------+		+--------------+------+------+-----------+---------------+
	| Raf to root | Yes | No | No | -- |		| Raf to root | Yes | No | No | -- |
	skipping to change at page 20, line 9 ¶		skipping to change at page 21, line 9 ¶
	6.1. Example of Flow from RPL-aware-leaf to root		6.1. 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 to avoid/detect		traffic to the root. The RPI header must be included to avoid/detect
	loops.		loops.
	RPL-aware-leaf (6LN) --> 6LR --> root (6LBR)		RPL-aware-leaf (6LN) --> 6LR --> root (6LBR)
	This situation is the same case as storing mode.		This situation is the same case as storing mode.
	+-------------------+-----+-----+------+		+-------------------+-----+------+------+
	| Header | 6LN | 6LR | 6LBR |		| Header | 6LN | 6LR | 6LBR |
	+-------------------+-----+-----+------+		+-------------------+-----+------+------+
	| Inserted headers | RPI | -- | -- |		| Inserted headers | RPI | -- | -- |
	| Removed headers | -- | -- | RPI |		| Removed headers | -- | -- | RPI |
	| Re-added headers | -- | -- | RPI |		| Re-added headers | -- | RPI | -- |
	| Modified headers | -- | -- | -- |		| Modified headers | -- | -- | -- |
	| Untouched headers | -- | -- | -- |		| Untouched headers | -- | -- | -- |
	+-------------------+-----+-----+------+		+-------------------+-----+------+------+
	Non Storing: Summary of the use of headers from RPL-aware-leaf to		Non Storing: Summary of the use of headers from RPL-aware-leaf to
	root		root
	6.2. Example of Flow from root to RPL-aware-leaf		6.2. Example of Flow from root to RPL-aware-leaf
	In this case the flow comprises:		In this case the flow comprises:
	root (6LBR)--> 6LR --> RPL-aware-leaf (6LN)		root (6LBR)--> 6LR --> RPL-aware-leaf (6LN)
	The 6LBR will insert an RH3, and may optionally insert an RPI header.		The 6LBR will insert an RH3, and may optionally insert an RPI header.
	No IP-in-IP header is necessary as the traffic originates with an RPL		No IP-in-IP header is necessary as the traffic originates with an RPL
	aware node.		aware node, the 6LBR. The destination is known to 6LBR because, the
			root knows the whole topology in non-storing mode.
	+-------------------+-----------------+------+----------+		+-------------------+-----------------+------+----------+
	| Header | 6LBR | 6LR | 6LN |		| Header | 6LBR | 6LR | 6LN |
	+-------------------+-----------------+------+----------+		+-------------------+-----------------+------+----------+
	| Inserted headers | (opt: RPI), RH3 | -- | -- |		| Inserted headers | (opt: RPI), RH3 | -- | -- |
	| Removed headers | -- | -- | RH3,RPI |		| Removed headers | -- | -- | RH3,RPI |
	| Re-added headers | -- | -- | -- |		| Re-added headers | -- | -- | -- |
	| Modified headers | -- | RH3 | -- |		| Modified headers | -- | RH3 | -- |
	| Untouched headers | -- | -- | -- |		| Untouched headers | -- | -- | -- |
	+-------------------+-----------------+------+----------+		+-------------------+-----------------+------+----------+
	Non Storing: Summary of the use of headers from root to RPL-aware-		Non Storing: Summary of the use of headers from root to RPL-aware-
	leaf		leaf
	6.3. Example of Flow from root to not-RPL-aware-leaf		6.3. 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 --> not-RPL-aware-leaf (IPv6 node)		root (6LBR)--> 6LR --> not-RPL-aware-leaf (IPv6 node)
			In 6LBR the RH3 is added, modified in each intermediate 6LR and it is
	In 6LBR the RH3 is added, and modified in 6LR where it is fully		fully consumed in the last 6LR, but left there. If the RPI is left
	consumed, but left there. If the RPI is left present, the IPv6 node		present, the IPv6 node which does not understand it will drop it,
	which does not understand it will drop it, therefore the RPI should		therefore the RPI should be removed before reaching the IPv6-only
	be removed before reaching the IPv6-only node. To permit removal, an		node. To permit removal, an IP-in-IP header (hop-by-hop) or
	IP-in-IP header (hop-by-hop) or addressed to the last 6LR is		addressed to the last 6LR is necessary. Due the complete knowledge
	necessary. Due the complete knowledge of the topology at the root,		of the topology at the root, the 6LBR is able to address the IP-in-IP
	the 6LBR is able to address the IP-in-IP header to the last 6LR.		header to the last 6LR.
	Omitting the RPI entirely is therefore a better solution, as no IP-		Omitting the RPI entirely is therefore a better solution, as no IP-
	in-IP header is necessary.		in-IP header is necessary.
	+-------------------+------+-----+------+		+-------------------+------+-----+------+
	| Header | 6LBR | 6LR | IPv6 |		| Header | 6LBR | 6LR | IPv6 |
	+-------------------+------+-----+------+		+-------------------+------+-----+------+
	| Inserted headers | RH3 | -- | -- |		| Inserted headers | RH3 | -- | -- |
	| Removed headers | -- | -- | -- |		| Removed headers | -- | -- | -- |
	| Re-added headers | -- | -- | -- |		| Re-added headers | -- | -- | -- |
	skipping to change at page 22, line 11 ¶		skipping to change at page 23, line 11 ¶
	Non Storing: Summary of the use of headers from not-RPL-aware-leaf to		Non Storing: Summary of the use of headers from not-RPL-aware-leaf to
	root		root
	6.5. Example of Flow from RPL-aware-leaf to Internet		6.5. 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 --> root (6LBR) --> Internet		RPL-aware-leaf (6LN) --> 6LR --> root (6LBR) --> Internet
	This case requires that the RPI be added, but remoted by the 6LBR.		This case requires that the RPI be added, but removed by the 6LBR.
	The 6LN must therefore add the RPI inside an IP-in-IP header,		The 6LN must therefore add the RPI inside an IP-in-IP header,
	addressed to the root. This case is identical to storing-mode case.		addressed to the root. 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.
	+-----------------+---------------+------+---------------+----------+		+-----------------+---------------+------+---------------+----------+
	| Header | 6LN | 6LR | 6LBR | Internet |		| Header | 6LN | 6LR | 6LBR | Internet |
	+-----------------+---------------+------+---------------+----------+		+-----------------+---------------+------+---------------+----------+
	skipping to change at page 23, line 34 ¶		skipping to change at page 24, line 34 ¶
	6.7. Example of Flow from not-RPL-aware-leaf to Internet		6.7. 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 (6LN) --> 6LR --> root (6LBR) --> Internet		not-RPL-aware-leaf (6LN) --> 6LR --> root (6LBR) --> Internet
	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, the first 6LN will		node. As RPL headers are added in the IPv6 node, the first 6LN will
	add an RPI header inside a new IP-in-IP header. The IP-in-IP header		add an RPI header inside a new IP-in-IP header. The IP-in-IP header
	will be addressed to the root. This case is identical to the		will be addressed to the root. This case is identical to the
	storing-mode case.		storing-mode case (Section 5.7).
	+-----------------+------+---------------+---------------+----------+		+-----------------+------+---------------+---------------+----------+
	| Header | IPv6 | 6LR | 6LBR | Internet |		| Header | IPv6 | 6LR | 6LBR | Internet |
	+-----------------+------+---------------+---------------+----------+		+-----------------+------+---------------+---------------+----------+
	| Inserted | -- | IP-in-IP(RPI) | -- | -- |		| Inserted | -- | IP-in-IP(RPI) | -- | -- |
	| headers | | | | |		| headers | | | | |
	| Removed headers | -- | -- | IP-in-IP(RPI) | -- |		| Removed headers | -- | -- | IP-in-IP(RPI) | -- |
	| Re-added | -- | -- | -- | -- |		| Re-added | -- | -- | -- | -- |
	| headers | | | | |		| headers | | | | |
	| Modified | -- | -- | -- | -- |		| Modified | -- | -- | -- | -- |
	skipping to change at page 24, line 9 ¶		skipping to change at page 25, line 9 ¶
	| headers | | | | |		| headers | | | | |
	+-----------------+------+---------------+---------------+----------+		+-----------------+------+---------------+---------------+----------+
	Non Storing: Summary of the use of headers from not-RPL-aware-leaf to		Non Storing: Summary of the use of headers from not-RPL-aware-leaf to
	Internet		Internet
	6.8. Example of Flow from Internet to non-RPL-aware-leaf		6.8. Example of Flow from Internet to non-RPL-aware-leaf
	In this case the flow comprises:		In this case the flow comprises:
	Internet --> root (6LBR) --> 6LR --> not-RPL-aware-leaf (6LN)		Internet --> root (6LBR) --> 6LR --> not-RPL-aware-leaf (IPv6 node)
	The 6LBR must add an RH3 header inside an IP-in-IP header. The 6LBR		The 6LBR must add an RH3 header inside an IP-in-IP header. The 6LBR
	will know the path, and will recognize that the final node is not an		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 from		RPL capable node as it will have received the connectivity DAO from
	the nearest 6LR. The 6LBR can therefore make the IP-in-IP header		the nearest 6LR. The 6LBR can therefore make the IP-in-IP header
	destination be the last 6LR. The 6LBR will zero the flow label upon		destination be the last 6LR. The 6LBR will set to zero the flow
	entry in order to aid compression.		label upon entry in order to aid compression.
	+----------+---------+-----------------------+---------------+------+		+----------+---------+-----------------------+---------------+------+
	| Header | Interne | 6LBR | 6LR | IPv6 |		| Header | Interne | 6LBR | 6LR | IPv6 |
	| | t | | | |		| | t | | | |
	+----------+---------+-----------------------+---------------+------+		+----------+---------+-----------------------+---------------+------+
	| Inserted | -- | IP-in-IP(RH3,opt:RPI) | -- | -- |		| Inserted | -- | IP-in-IP(RH3,opt:RPI) | -- | -- |
	| headers | | | | |		| headers | | | | |
	| Removed | -- | -- | IP-in-IP(RH3, | -- |		| Removed | -- | -- | IP-in-IP(RH3, | -- |
	| headers | | | RPI) | |		| headers | | | RPI) | |
	| Re-added | -- | -- | -- | -- |		| Re-added | -- | -- | -- | -- |
	skipping to change at page 25, line 34 ¶		skipping to change at page 26, line 34 ¶
	| headers | | | | |		| headers | | | | |
	+----------+---------------+--------------+-----+-------------------+		+----------+---------------+--------------+-----+-------------------+
	Non Storing: Summary of the use of headers for RPL-aware-leaf to RPL-		Non Storing: Summary of the use of headers for RPL-aware-leaf to RPL-
	aware-leaf		aware-leaf
	6.10. Example of Flow from RPL-aware-leaf to not-RPL-aware-leaf		6.10. 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 --> root (6LBR) --> 6LR --> not-RPL-aware 6LN		6LN --> 6LR --> root (6LBR) --> 6LR --> not-RPL-aware (IPv6 node)
	As in the previous case, the 6LN will insert an RPI header which MUST		As in the previous case, the 6LN will insert an RPI header which MUST
	be in an IP-in-IP header addressed to the root so that the 6LBR can		be in an IP-in-IP header addressed to the root so that the 6LBR can
	remove this RPI. The 6LBR will then insert an RH3 inside a new IP-		remove this RPI. The 6LBR will then insert an RH3 inside a new IP-
	in-IP header addressed to the 6LN above the destination node.		in-IP header addressed to the 6LN above the destination node.
	+-----------+---------------+---------------+----------------+------+		+-----------+---------------+---------------+----------------+------+
	| Header | 6LN | 6LBR | 6LR | IPv6 |		| Header | 6LN | 6LBR | 6LR | IPv6 |
	+-----------+---------------+---------------+----------------+------+		+-----------+---------------+---------------+----------------+------+
	| Inserted | IP-in-IP(RPI) | IP-in-IP(RH3, | -- | -- |		| Inserted | IP-in-IP(RPI) | IP-in-IP(RH3, | -- | -- |
	skipping to change at page 27, line 10 ¶		skipping to change at page 28, line 10 ¶
	+------------+------+---------------+---------------+---------------+		+------------+------+---------------+---------------+---------------+
	Non Storing: Summary of the use of headers from not-RPL-aware-leaf to		Non Storing: Summary of the use of headers from not-RPL-aware-leaf to
	RPL-aware-leaf		RPL-aware-leaf
	6.12. Example of Flow from not-RPL-aware-leaf to not-RPL-aware-leaf		6.12. Example of Flow from not-RPL-aware-leaf to not-RPL-aware-leaf
	In this case the flow comprises:		In this case the flow comprises:
	not-RPL-aware 6LN --> 6LR --> root (6LBR) --> 6LR --> not-RPL-aware		not-RPL-aware 6LN --> 6LR --> root (6LBR) --> 6LR --> not-RPL-aware
	6LN		(IPv6 node)
	This scenario is the combination of the previous two cases.		This scenario is the combination of the previous two cases.
	+----------+-----+-------------+--------------+--------------+------+		+----------+-----+-------------+--------------+--------------+------+
	| Header | IPv | 6LR | 6LBR | 6LR | IPv6 |		| Header | IPv | 6LR | 6LBR | 6LR | IPv6 |
	| | 6 | | | | |		| | 6 | | | | |
	+----------+-----+-------------+--------------+--------------+------+		+----------+-----+-------------+--------------+--------------+------+
	| Inserted | -- | IP-in- | IP-in- | -- | -- |		| Inserted | -- | IP-in- | IP-in- | -- | -- |
	| headers | | IP(RPI) | IP(RH3) | | |		| headers | | IP(RPI) | IP(RH3) | | |
	| Removed | -- | -- | IP-in- | IP-in- | -- |		| Removed | -- | -- | IP-in- | IP-in- | -- |
	skipping to change at page 27, line 45 ¶		skipping to change at page 28, line 45 ¶
	7. Observations about the problem		7. Observations about the problem
	7.1. Storing mode		7.1. Storing mode
	In the completely general storing case, which includes not-RPL aware		In the completely general storing case, which includes not-RPL aware
	leaf nodes, it is not possible for a sending node to know if the		leaf nodes, it is not possible for a sending node to know if the
	destination is RPL aware, and therefore it must always use hop-by-hop		destination is RPL aware, and therefore it must always use hop-by-hop
	IP-in-IP encapsulation, and it can never omit the IP-in-IP		IP-in-IP encapsulation, and it can never omit the IP-in-IP
	encapsulation. See table Table 1		encapsulation. See table Table 1
	The simplest fully general stiaution for storing mode is to always		The simplest fully general approach for storing mode is to always put
	put in hop-by-hop IP-in-IP headers. [I-D.ietf-roll-routing-dispatch]		in hop-by-hop IP-in-IP headers. [I-D.ietf-roll-routing-dispatch]
	shows that this hop-by-hop IP-in-IP header can be compressed down to		shows that this hop-by-hop IP-in-IP header can be compressed down to
	{TBD} bytes.		{TBD} bytes.
	There are potential significant advantages to having a single code		There are potential significant advantages to having a single code
	path that always processes IP-in-IP headers with no options.		path that always processes IP-in-IP headers with no options.
	If all RPL aware nodes can be told/configured that there are no non-		If all RPL aware nodes can be told/configured that there are no non-
	RPL aware leaf nodes, then the only case where an IP-in-IP header is		RPL aware leaf nodes, then the only case where an IP-in-IP header is
	needed is when communicating outside the LLN. The 6LBR knows well		needed is when communicating outside the LLN. The 6LBR knows well
	when the communication is from the outside, and the 6LN can tell by		when the communication is from the outside, and the 6LN can tell by
	skipping to change at page 28, line 24 ¶		skipping to change at page 29, line 24 ¶
	in relatively closed systems such as in building or industrial		in relatively closed systems such as in building or industrial
	automation. Again, there are advantages to having a single code		automation. Again, there are advantages to having a single code
	path.		path.
	In order to support the above two cases with full generality, the		In order to support the above two cases with full generality, the
	different situations (always do IP-in-IP vs never use IP-in-IP)		different situations (always do IP-in-IP vs never use IP-in-IP)
	should be signaled in the RPL protocol itself.		should be signaled in the RPL protocol itself.
	7.2. Non-Storing mode		7.2. Non-Storing mode
	This the non-storing case, dealing with non-RPL aware leaf nodes is		In the non-storing case, dealing with non-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 nodes, and all traffic flows through the root		connectivity of all DODAG nodes, and all traffic flows through the
	node.		root node.
	The 6LBR can recognize non-RPL aware leaf nodes because it will		The 6LBR can recognize non-RPL aware leaf nodes because it will
	receive a DAO about that node from the 6LN immediately above that		receive a DAO about that node from the 6LN immediately above that
	node. This means that the non-storing mode case can avoid ever using		node. This means that the non-storing mode case can avoid ever using
	hop-by-hop IP-in-IP headers.		hop-by-hop IP-in-IP headers.
	It is unclear what it would mean for an RH3 header to be present in a		It is unclear what it would mean for an RH3 header to be present in a
	hop-by-hop IP-in-IP header. The receiving node ought to consume the		hop-by-hop IP-in-IP header. The receiving node ought to consume the
	IP-in-IP header, and therefore consume the RH3 as well, and then		IP-in-IP header, and therefore consume the RH3 as well, and then
	attempt to send the packet again. But intermediate 6LN nodes would		attempt to send the packet again. But intermediate 6LN nodes would
	not know how to forward the packet, so the RH3 would need to be		not know how to forward the packet (because they do not save the
	retained. This is a new kind of IPv6 packet processing. Therefore		sate), so the RH3 would need to be retained. This is a new kind of
	it may be that on the outbound leg of non-storing RPL networks, that		IPv6 packet processing. Therefore it may be that on the outbound leg
	hop-by-hop IP-in-IP header can NOT be used.		of non-storing RPL networks, that hop-by-hop IP-in-IP header can NOT
			be used.
	[I-D.ietf-roll-routing-dispatch] shows how the destination=root, and		[I-D.ietf-roll-routing-dispatch] shows how the destination=root, and
	destination=6LN IP-in-IP header can be compressed down to {TBD}		destination=6LN IP-in-IP header can be compressed down to {TBD}
	bytes.		bytes.
	Unlike in the storing mode case, there are no need for all nodes to		Unlike in the storing mode case, there is no need for all nodes to
	know about the existence of non-RPL aware nodes. Only the 6LBR needs		know about the existence of non-RPL aware nodes. Only the 6LBR needs
	to change when there are non-RPL aware nodes. Further, in the non-		to change when there are non-RPL aware nodes. Further, in the non-
	storing case, the 6LBR is informed by the DAOs when there are non-RPL		storing case, the 6LBR is informed by the DAOs when there are non-RPL
	aware nodes.		aware nodes.
	8. 6LoRH Compression cases		8. 6LoRH Compression cases
	The [I-D.ietf-roll-routing-dispatch] proposes a compression method		The [I-D.ietf-roll-routing-dispatch] proposes a compression method
	for RPI, RH3 and IPv6-in-IPv6.		for RPI, RH3 and IPv6-in-IPv6.
	In Storing Mode, for the examples of Flow from RPL-aware-leaf to non-		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		RPL-aware-leaf and non-RPL-aware-leaf to non-RPL-aware-leaf comprise
	an IP-in-IP and RPI compression headers. The type of this case is		an IP-in-IP and RPI compression headers. The type of this case is
	critical since IP-in-IP is encapsulating a RPI header.		critical since IP-in-IP is encapsulating a RPI header.
	+--+-----+---+--------------+-----------+-------------+-------------+		+--+-----+---+--------------+-----------+-------------+-------------+
	|1 | 0|0 |TSE| 6LoRH Type 6 | Hop Limit | RPI - 6LoRH | LOWPAN IPHC |		|1 | 0|0 |TSE| 6LoRH Type 6 | Hop Limit | RPI - 6LoRH | LOWPAN IPHC |
	+--+-----+---+--------------+-----------+-------------+-------------+		+--+-----+---+--------------+-----------+-------------+-------------+
	Figure 5: Critical IP-in-IP (RPI).		Figure 4: Critical IP-in-IP (RPI).
	9. IANA Considerations		9. IANA Considerations
	There are no IANA considerations related to this document.		There are no IANA considerations related to this document.
	10. Security Considerations		10. Security Considerations
	The security considerations covering of [RFC6553] and [RFC6554] apply		The security considerations covering of [RFC6553] and [RFC6554] apply
	when the packets get into RPL Domain.		when the packets get into RPL Domain.
	11. Acknowledgments		11. Acknowledgments
	This work is partially funded by the FP7 Marie Curie Initial Training		This work is partially funded by the FP7 Marie Curie Initial Training
	Network (ITN) METRICS project (grant agreement No. 607728).		Network (ITN) METRICS project (grant agreement No. 607728).
	The authors would like to acknowledge the review, feedback, and		The authors would like to acknowledge the review, feedback, and
	comments of Thomas Watteyne, Xavier Vilajosana, Robert Cragie, Simon		comments of Robert Cragie, Simon Duquennoy, Cenk Guendogan, Peter van
	Duquennoy and Peter van der Stok.		der Stok, Xavier Vilajosana and Thomas Watteyne.
	12. References		12. References
	12.1. Normative References		12.1. Normative References
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119,		Requirement Levels", BCP 14, RFC 2119,
	DOI 10.17487/RFC2119, March 1997,		DOI 10.17487/RFC2119, March 1997,
	<http://www.rfc-editor.org/info/rfc2119>.		<http://www.rfc-editor.org/info/rfc2119>.
	[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, December 1998.
	December 1998, <http://www.rfc-editor.org/info/rfc2460>.
	[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,
	<http://www.rfc-editor.org/info/rfc6550>.		<http://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 30, line 27 ¶		skipping to change at page 31, line 27 ¶
	[RFC6554] Hui, J., Vasseur, JP., Culler, D., and V. Manral, "An IPv6		[RFC6554] Hui, J., Vasseur, JP., Culler, D., and V. Manral, "An IPv6
	Routing Header for Source Routes with the Routing Protocol		Routing Header for Source Routes with the Routing Protocol
	for Low-Power and Lossy Networks (RPL)", RFC 6554,		for Low-Power and Lossy Networks (RPL)", RFC 6554,
	DOI 10.17487/RFC6554, March 2012,		DOI 10.17487/RFC6554, March 2012,
	<http://www.rfc-editor.org/info/rfc6554>.		<http://www.rfc-editor.org/info/rfc6554>.
	12.2. Informative References		12.2. Informative References
	[I-D.ietf-6man-rfc2460bis]		[I-D.ietf-6man-rfc2460bis]
	Deering, S. and R. Hinden, "Internet Protocol, Version 6		Deering, D. and R. Hinden, "Internet Protocol, Version 6
	(IPv6) Specification", draft-ietf-6man-rfc2460bis-04 (work		(IPv6) Specification", draft-ietf-6man-rfc2460bis-05 (work
	in progress), March 2016.		in progress), June 2016.
	[I-D.ietf-6tisch-architecture]		[I-D.ietf-6tisch-architecture]
	Thubert, P., "An Architecture for IPv6 over the TSCH mode		Thubert, P., "An Architecture for IPv6 over the TSCH mode
	of IEEE 802.15.4", draft-ietf-6tisch-architecture-10 (work		of IEEE 802.15.4", draft-ietf-6tisch-architecture-10 (work
	in progress), June 2016.		in progress), June 2016.
	[I-D.ietf-roll-routing-dispatch]		[I-D.ietf-roll-routing-dispatch]
	Thubert, P., Bormann, C., Toutain, L., and R. Cragie,		Thubert, P., Bormann, C., Toutain, L., and R. Cragie,
	"6LoWPAN Routing Header", draft-ietf-roll-routing-		"6LoWPAN Routing Header", draft-ietf-roll-routing-
	dispatch-00 (work in progress), March 2016.		dispatch-00 (work in progress), March 2016.
End of changes. 53 change blocks.
	183 lines changed or deleted		159 lines changed or added
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