< draft-ietf-6lo-routing-dispatch-04.txt		draft-ietf-6lo-routing-dispatch-05.txt >
	6lo P. Thubert, Ed.		6lo P. Thubert, Ed.
	Internet-Draft Cisco		Internet-Draft Cisco
	Intended status: Standards Track C. Bormann		Intended status: Standards Track C. Bormann
	Expires: July 26, 2016 Uni Bremen TZI		Expires: August 15, 2016 Uni Bremen TZI
	L. Toutain		L. Toutain
	IMT-TELECOM Bretagne		IMT-TELECOM Bretagne
	R. Cragie		R. Cragie
	ARM		ARM
	January 23, 2016		February 12, 2016
	6LoWPAN Routing Header		6LoWPAN Routing Header
	draft-ietf-6lo-routing-dispatch-04		draft-ietf-6lo-routing-dispatch-05
	Abstract		Abstract
	This specification introduces a new 6LoWPAN dispatch type for use in		This specification introduces a new 6LoWPAN dispatch type for use in
	6LoWPAN Route-Over topologies, that initially covers the needs of RPL		6LoWPAN Route-Over topologies, that initially covers the needs of RPL
	(RFC6550) data packets compression. Using this dispatch type, this		(RFC6550) data packets compression. Using this dispatch type, this
	specification defines a method to compress RPL Option (RFC6553)		specification defines a method to compress RPL Option (RFC6553)
	information and Routing Header type 3 (RFC6554), an efficient IP-in-		information and Routing Header type 3 (RFC6554), an efficient IP-in-
	IP technique and is extensible for more applications.		IP technique and is extensible for more applications.
	skipping to change at page 1, line 40 ¶		skipping to change at page 1, line 40 ¶
	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 July 26, 2016.		This Internet-Draft will expire on August 15, 2016.
	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
	(http://trustee.ietf.org/license-info) in effect on the date of		(http://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 1, line 72 ¶		skipping to change at page 1, line 72 ¶
	3.1. New Routing Header Dispatch (6LoRH) . . . . . . . . . . . 6		3.1. New Routing Header Dispatch (6LoRH) . . . . . . . . . . . 6
	3.2. Placement Of 6LoRH headers . . . . . . . . . . . . . . . 6		3.2. Placement Of 6LoRH headers . . . . . . . . . . . . . . . 6
	3.2.1. Relative To Non-6LoRH Headers . . . . . . . . . . . . 7		3.2.1. Relative To Non-6LoRH Headers . . . . . . . . . . . . 7
	3.2.2. Relative To Other 6LoRH Headers . . . . . . . . . . . 7		3.2.2. Relative To Other 6LoRH Headers . . . . . . . . . . . 7
	4. 6LoWPAN Routing Header General Format . . . . . . . . . . . . 8		4. 6LoWPAN Routing Header General Format . . . . . . . . . . . . 8
	4.1. Elective Format . . . . . . . . . . . . . . . . . . . . . 8		4.1. Elective Format . . . . . . . . . . . . . . . . . . . . . 8
	4.2. Critical Format . . . . . . . . . . . . . . . . . . . . . 9		4.2. Critical Format . . . . . . . . . . . . . . . . . . . . . 9
	4.3. Compressing Addresses . . . . . . . . . . . . . . . . . . 9		4.3. Compressing Addresses . . . . . . . . . . . . . . . . . . 9
	4.3.1. Coalescence . . . . . . . . . . . . . . . . . . . . . 10		4.3.1. Coalescence . . . . . . . . . . . . . . . . . . . . . 10
	4.3.2. DODAG Root Address Determination . . . . . . . . . . 10		4.3.2. DODAG Root Address Determination . . . . . . . . . . 10
	5. The Routing Header Type 3 (RH3) 6LoRH Header . . . . . . . . 11		5. The SRH 6LoRH Header . . . . . . . . . . . . . . . . . . . . 11
	5.1. RH3-6LoRH General Operation . . . . . . . . . . . . . . . 13		5.1. Encoding . . . . . . . . . . . . . . . . . . . . . . . . 11
	5.2. The Design Point of Popping Entries . . . . . . . . . . . 13		5.2. SRH-6LoRH General Operation . . . . . . . . . . . . . . . 13
	5.3. Compression Reference . . . . . . . . . . . . . . . . . . 14		5.2.1. Uncompressed SRH Operation . . . . . . . . . . . . . 13
	5.4. Popping Headers . . . . . . . . . . . . . . . . . . . . . 15		5.2.2. 6LoRH-Compressed SRH Operation . . . . . . . . . . . 13
	5.5. Forwarding . . . . . . . . . . . . . . . . . . . . . . . 16		5.2.3. Inner LOWPAN_IPHC Compression . . . . . . . . . . . . 14
	6. The RPL Packet Information 6LoRH . . . . . . . . . . . . . . 16		5.3. The Design Point of Popping Entries . . . . . . . . . . . 14
	6.1. Compressing the RPLInstanceID . . . . . . . . . . . . . . 18		5.4. Compression Reference for SRH-6LoRH header entries . . . 15
	6.2. Compressing the SenderRank . . . . . . . . . . . . . . . 18		5.5. Popping Headers . . . . . . . . . . . . . . . . . . . . . 16
			5.6. Forwarding . . . . . . . . . . . . . . . . . . . . . . . 17
			6. The RPL Packet Information 6LoRH . . . . . . . . . . . . . . 17
			6.1. Compressing the RPLInstanceID . . . . . . . . . . . . . . 19
			6.2. Compressing the SenderRank . . . . . . . . . . . . . . . 19
	6.3. The Overall RPI-6LoRH encoding . . . . . . . . . . . . . 19		6.3. The Overall RPI-6LoRH encoding . . . . . . . . . . . . . 19
	7. The IP-in-IP 6LoRH Header . . . . . . . . . . . . . . . . . . 21		7. The IP-in-IP 6LoRH Header . . . . . . . . . . . . . . . . . . 22
	8. Security Considerations . . . . . . . . . . . . . . . . . . . 22		8. Security Considerations . . . . . . . . . . . . . . . . . . . 23
	9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22		9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23
	9.1. Reserving Space in 6LoWPAN Dispatch Page 1 . . . . . . . 22		9.1. Reserving Space in 6LoWPAN Dispatch Page 1 . . . . . . . 23
	9.2. New 6LoWPAN Routing Header Type Registry . . . . . . . . 23		9.2. New 6LoWPAN Routing Header Type Registry . . . . . . . . 24
	10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 23		10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 24
	11. References . . . . . . . . . . . . . . . . . . . . . . . . . 23		11. References . . . . . . . . . . . . . . . . . . . . . . . . . 24
	11.1. Normative References . . . . . . . . . . . . . . . . . . 23		11.1. Normative References . . . . . . . . . . . . . . . . . . 24
	11.2. Informative References . . . . . . . . . . . . . . . . . 24		11.2. Informative References . . . . . . . . . . . . . . . . . 25
	Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 25		Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 26
	A.1. Examples Compressing The RPI . . . . . . . . . . . . . . 25		A.1. Examples Compressing The RPI . . . . . . . . . . . . . . 26
	A.2. Example Of Downward Packet In Non-Storing Mode . . . . . 27		A.2. Example Of Downward Packet In Non-Storing Mode . . . . . 28
	A.3. Example of RH3-6LoRH life-cycle . . . . . . . . . . . . . 28		A.3. Example of SRH-6LoRH life-cycle . . . . . . . . . . . . . 30
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 30		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 32
	1. Introduction		1. Introduction
	The design of Low Power and Lossy Networks (LLNs) is generally		The design of Low Power and Lossy Networks (LLNs) is generally
	focused on saving energy, a very constrained resource in most cases.		focused on saving energy, a very constrained resource in most cases.
	The other constraints, such as the memory capacity and the duty		The other constraints, such as the memory capacity and the duty
	cycling of the LLN devices, derive from that primary concern. Energy		cycling of the LLN devices, derive from that primary concern. Energy
	is often available from primary batteries that are expected to last		is often available from primary batteries that are expected to last
	for years, or is scavenged from the environment in very limited		for years, or is scavenged from the environment in very limited
	quantities. Any protocol that is intended for use in LLNs must be		quantities. Any protocol that is intended for use in LLNs must be
	skipping to change at page 1, line 174 ¶		skipping to change at page 1, line 178 ¶
	implementations.		implementations.
	As an example, the Routing Protocol for Low Power and Lossy Networks		As an example, the Routing Protocol for Low Power and Lossy Networks
	[RFC6550] (RPL) is designed to optimize the routing operations in		[RFC6550] (RPL) is designed to optimize the routing operations in
	constrained LLNs. As part of this optimization, RPL requires the		constrained LLNs. As part of this optimization, RPL requires the
	addition of RPL Packet Information (RPI) in every packet, as defined		addition of RPL Packet Information (RPI) in every packet, as defined
	in Section 11.2 of [RFC6550].		in Section 11.2 of [RFC6550].
	The RPL Option for Carrying RPL Information in Data-Plane Datagrams		The RPL Option for Carrying RPL Information in Data-Plane Datagrams
	[RFC6553] specification indicates how the RPI can be placed in a RPL		[RFC6553] specification indicates how the RPI can be placed in a RPL
	Option for use in an IPv6 Hop-by-Hop header.		Option (RPL-OPT) that is placed in an IPv6 Hop-by-Hop header.
	This representation demands a total of 8 bytes, while in most cases		This representation demands a total of 8 bytes, while in most cases
	the actual RPI payload requires only 19 bits. Since the Hop-by-Hop		the actual RPI payload requires only 19 bits. Since the Hop-by-Hop
	header must not flow outside of the RPL domain, it must be inserted		header must not flow outside of the RPL domain, it must be inserted
	in packets entering the domain and be removed from packets that leave		in packets entering the domain and be removed from packets that leave
	the domain. In both cases, this operation implies an IP-in-IP		the domain. In both cases, this operation implies an IP-in-IP
	encapsulation.		encapsulation.
			Additionally, in the case of the Non-Storing Mode of Operation (MOP),
			RPL requires a Source Routing Header (SRH) in all packets that are
			routed down a RPL graph. for that purpose, the [IPv6 Routing Header
			for Source Routes with RPL] (#RFC6554) specification defines the type
			3 Routing Header for IPv6 (RH3).
	------+--------- ^		------+--------- ^
	| Internet |		| Internet |
	| | Native IPv6		| | Native IPv6
	+-----+ |		+-----+ |
	| | Border Router (RPL Root) ^ | ^		| | Border Router (RPL Root) ^ | ^
	| | | | |		| | | | |
	+-----+ | | | IPv6 in		+-----+ | | | IPv6 in
	| | | | IPv6		| | | | IPv6
	o o o o | | | + RPI		o o o o | | | plus
	o o o o o o o o o | | | or RH3		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 | | | RPL SRH
	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 v v v		o o o o o o o o v v v
	o o o o		o o o o
	LLN		LLN
	Figure 2: IP-in-IP Encapsulation within the LLN.		Figure 2: IP-in-IP Encapsulation within the LLN.
	Additionally, in the case of the Non-Storing Mode of Operation (MOP),		With Non-Storing RPL, even if the source is a node in the same LLN,
	RPL requires a Routing Header type 3 (RH3) as defined in the IPv6		the packet must first reach up the graph to the root so that the root
	Routing Header for Source Routes with RPL [RFC6554] specification,		can insert the SRH to go down the graph. In any fashion, whether the
	for all packets that are routed down a RPL graph. With Non-Storing		packet was originated in a node in the LLN or outside the LLN, and
	RPL, even if the source is a node in the same LLN, the packet must		regardless of whether the packet stays within the LLN or not, as long
	first reach up the graph to the root so that the root can insert the		as the source of the packet is not the root itself, the source-
	RH3 to go down the graph. In any fashion, whether the packet was		routing operation also implies an IP-in-IP encapsulation at the root
	originated in a node in the LLN or outside the LLN, and regardless of		in order to insert the SRH.
	whether the packet stays within the LLN or not, as long as the source
	of the packet is not the root itself, the source-routing operation
	also implies an IP-in-IP encapsulation at the root in order to insert
	the RH3.
	6TiSCH [I-D.ietf-6tisch-architecture] specifies the operation of IPv6		6TiSCH [I-D.ietf-6tisch-architecture] specifies the operation of IPv6
	over the TimeSlotted Channel Hopping [RFC7554] (TSCH) mode of		over the TimeSlotted Channel Hopping [RFC7554] (TSCH) mode of
	operation of IEEE 802.15.4. The architecture requires the use of		operation of IEEE 802.15.4. The architecture requires the use of
	both RPL and the 6lo adaptation layer over IEEE 802.15.4. Because it		both RPL and the 6lo adaptation layer over IEEE 802.15.4. Because it
	inherits the constraints on frame size from the MAC layer, 6TiSCH		inherits the constraints on frame size from the MAC layer, 6TiSCH
	cannot afford to allocate 8 bytes per packet on the RPI. Hence the		cannot afford to allocate 8 bytes per packet on the RPI. Hence the
	requirement for 6LoWPAN header compression of the RPI.		requirement for 6LoWPAN header compression of the RPI.
	An extensible compression technique is required that simplifies IP-		An extensible compression technique is required that simplifies IP-
	skipping to change at page 1, line 264 ¶		skipping to change at page 1, line 270 ¶
	parser, a context being identified by a Page number. The		parser, a context being identified by a Page number. The
	specification defines 16 Pages.		specification defines 16 Pages.
	This draft operates within Page 1, which is indicated by a Dispatch		This draft operates within Page 1, which is indicated by a Dispatch
	Value of binary 11110001.		Value of binary 11110001.
	3.1. New Routing Header Dispatch (6LoRH)		3.1. New Routing Header Dispatch (6LoRH)
	This specification introduces a new 6LoWPAN Routing Header (6LoRH) to		This specification introduces a new 6LoWPAN Routing Header (6LoRH) to
	carry IPv6 routing information. The 6LoRH may contain source routing		carry IPv6 routing information. The 6LoRH may contain source routing
	information such as a compressed form of RH3, as well as other sorts		information such as a compressed form of SRH, as well as other sorts
	of routing information such as the RPI and IP-in-IP encapsulation.		of routing information such as the RPI and IP-in-IP encapsulation.
	The 6LoRH is expressed in a 6loWPAN packet as a Type-Length-Value		The 6LoRH is expressed in a 6loWPAN packet as a Type-Length-Value
	(TLV) field, which is extensible for future use.		(TLV) field, which is extensible for future use.
	This specification uses the bit pattern 10xxxxxx in Page 1 for the		This specification uses the bit pattern 10xxxxxx in Page 1 for the
	new 6LoRH Dispatch. Section 4 describes how RPL artifacts in data		new 6LoRH Dispatch. Section 4 describes how RPL artifacts in data
	packets can be compressed as 6LoRH headers.		packets can be compressed as 6LoRH headers.
	3.2. Placement Of 6LoRH headers		3.2. Placement Of 6LoRH headers
	skipping to change at page 1, line 310 ¶		skipping to change at page 1, line 316 ¶
	stripped from the packet, the whole chain goes with it. When one or		stripped from the packet, the whole chain goes with it. When one or
	more header(s) are inserted by an intermediate router, that router		more header(s) are inserted by an intermediate router, that router
	normally chains the headers and encapsulates the result in IP-in-IP.		normally chains the headers and encapsulates the result in IP-in-IP.
	With this specification, the chains of headers MUST be compressed in		With this specification, the chains of headers MUST be compressed in
	the same order as they appear in the uncompressed form of the packet.		the same order as they appear in the uncompressed form of the packet.
	This means that if there is more than one nested IP-in-IP		This means that if there is more than one nested IP-in-IP
	encapsulations, the first IP-in-IP encapsulation, with all its chain		encapsulations, the first IP-in-IP encapsulation, with all its chain
	of headers, is encoded first in the compressed form.		of headers, is encoded first in the compressed form.
	In the compressed form of a packet that has RH3 or HbH headers after		In the compressed form of a packet that has SRH or HbH headers after
	the inner IPv6 header (e.g. if there is no IP-in-IP encapsulation),		the inner IPv6 header (e.g. if there is no IP-in-IP encapsulation),
	these headers are placed in the 6LoRH form before the 6LOWPAN-IPHC		these headers are placed in the 6LoRH form before the 6LOWPAN-IPHC
	that represents the IPv6 header Section 3.2.1. If this packet gets		that represents the IPv6 header Section 3.2.1. If this packet gets
	encapsulated and some other RH3 or HbH headers are added as part of		encapsulated and some other SRH or HbH headers are added as part of
	the encapsulation, placing the 6LoRH headers next to one another may		the encapsulation, placing the 6LoRH headers next to one another may
	present an ambiguity on which header belong to which chain in the		present an ambiguity on which header belong to which chain in the
	uncompressed form.		uncompressed form.
	In order to disambiguate the headers that follow the inner IPv6		In order to disambiguate the headers that follow the inner IPv6
	header in the uncompressed form from the headers that follow the		header in the uncompressed form from the headers that follow the
	outer IP-in-IP header, it is REQUIRED that the compressed IP-in-IP		outer IP-in-IP header, it is REQUIRED that the compressed IP-in-IP
	header is placed last in the encoded chain. This means that the		header is placed last in the encoded chain. This means that the
	6LoRH headers that are found after the last compressed IP-in-IP		6LoRH headers that are found after the last compressed IP-in-IP
	header are to be inserted after the IPv6 header that is encoded with		header are to be inserted after the IPv6 header that is encoded with
	the 6LOWPAN-IPHC when decompressing the packet.		the 6LOWPAN-IPHC when decompressing the packet.
	With regards to the relative placement of the RH3 and the RPI in the		With regards to the relative placement of the SRH and the RPI in the
	compressed form, it is a design point for this specification that the		compressed form, it is a design point for this specification that the
	RH3 entries are consumed as the packet progresses down the LLN		SRH entries are consumed as the packet progresses down the LLN
	Section 5.2. In order to make this operation simpler in the		Section 5.3. In order to make this operation simpler in the
	compressed form, it is REQUIRED that the in the compressed form, the		compressed form, it is REQUIRED that the in the compressed form, the
	addresses along the source route path are encoded in the order of the		addresses along the source route path are encoded in the order of the
	path, and that the compressed RH3 are placed before the compressed		path, and that the compressed SRH are placed before the compressed
	RPI.		RPI.
	4. 6LoWPAN Routing Header General Format		4. 6LoWPAN Routing Header General Format
	The 6LoRH usesthe Dispatch Value Bit Pattern of 10xxxxxx in Page 1.		The 6LoRH usesthe Dispatch Value Bit Pattern of 10xxxxxx in Page 1.
	The Dispatch Value Bit Pattern is split in two forms of 6LoRH:		The Dispatch Value Bit Pattern is split in two forms of 6LoRH:
	Elective (6LoRHE) that may skipped if not understood		Elective (6LoRHE) that may skipped if not understood
	skipping to change at page 1, line 417 ¶		skipping to change at page 1, line 423 ¶
	4.3. Compressing Addresses		4.3. Compressing Addresses
	The general technique used in this draft to compress an address is		The general technique used in this draft to compress an address is
	first to determine a reference that as a long prefix match with this		first to determine a reference that as a long prefix match with this
	address, and then elide that matching piece. In order to reconstruct		address, and then elide that matching piece. In order to reconstruct
	the compress address, the receiving node will perform the process of		the compress address, the receiving node will perform the process of
	coalescence described in section Section 4.3.1.		coalescence described in section Section 4.3.1.
	One possible reference is the root of the RPL DODAG that is being		One possible reference is the root of the RPL DODAG that is being
	traversed. It is used to compress an outer IP-in-IP header, and if		traversed. It is used by 6LoRH as the reference to compress an outer
	the root is the source of the packet, the technique allows to fully		IP header, in case of an IP-in-IP encapsulation. If the root is the
	elide the source address in the compressed form of the IP header. If		source of the packet, this technique allows to fully elide the source
	the root is not the encapsulator, then the encapsulator address may		address in the compressed form of the IP header. If the root is not
	still be compressed using the root as reference. How the address of		the encapsulator, then the encapsulator address may still be
	the root is determined is discussed in Section 4.3.2.		compressed using the root as reference. How the address of the root
			is determined is discussed in Section 4.3.2.
	Once the address of the source of the packet is determined, it		Once the address of the source of the packet is determined, it
	becomes the reference for the compression of the addresses that are		becomes the reference for the compression of the addresses that are
	located in compressed RH3 headers that are present inside the IP-in-		located in compressed SRH headers that are present inside the IP-in-
	IP encapsulation in the uncompressed form.		IP encapsulation in the uncompressed form.
	4.3.1. Coalescence		4.3.1. Coalescence
	An IPv6 compressed address is coalesced with a reference address by		An IPv6 compressed address is coalesced with a reference address by
	overriding the N rightmost bytes of the reference address with the		overriding the N rightmost bytes of the reference address with the
	compressed address, where N is the length of the compressed address,		compressed address, where N is the length of the compressed address,
	as indicated by the Type of the RH3-6LoRH header in Figure 7.		as indicated by the Type of the SRH-6LoRH header in Figure 7.
	The reference address MAY be a compressed address as well, in which		The reference address MAY be a compressed address as well, in which
	case it MUST be compressed in a form that is of an equal or greater		case it MUST be compressed in a form that is of an equal or greater
	length than the address that is being coalesced.		length than the address that is being coalesced.
	A compressed address is expanded by coalescing it with a reference		A compressed address is expanded by coalescing it with a reference
	address. In the particular case of a Type 4 RH3-6LoRH, the address		address. In the particular case of a Type 4 SRH-6LoRH, the address
	is expressed in full and the coalescence is a complete override as		is expressed in full and the coalescence is a complete override as
	illustrated in Figure 5.		illustrated in Figure 5.
	RRRRRRRRRRRRRRRRRRRR reference address, may be compressed or not		RRRRRRRRRRRRRRRRRRRR reference address, may be compressed or not
	CCCCCCC compressed address, shorter or same as reference		CCCCCCC compressed address, shorter or same as reference
	RRRRRRRRRRRRRCCCCCCC Coalesced address, same compression as reference		RRRRRRRRRRRRRCCCCCCC Coalesced address, same compression as reference
	Figure 5: Coalescing addresses.		Figure 5: Coalescing addresses.
	skipping to change at page 1, line 471 ¶		skipping to change at page 1, line 478 ¶
	With [RFC6282], the state is provided to the stack by the 6LoWPAN		With [RFC6282], the state is provided to the stack by the 6LoWPAN
	Neighbor Discovery Protocol (NDP) [RFC6775]. NDP exchanges the		Neighbor Discovery Protocol (NDP) [RFC6775]. NDP exchanges the
	context through 6LoWPAN Context Option in Router Advertisement (RA)		context through 6LoWPAN Context Option in Router Advertisement (RA)
	messages. In the compressed form of the packet, the context can be		messages. In the compressed form of the packet, the context can be
	signaled in a Context Identifier Extension.		signaled in a Context Identifier Extension.
	With this specification, the compression information is provided to		With this specification, the compression information is provided to
	the stack by RPL, and RPL exchanges it through the DODAGID field in		the stack by RPL, and RPL exchanges it through the DODAGID field in
	the DAG Information Object (DIO) messages, as described in more		the DAG Information Object (DIO) messages, as described in more
	details below. In the compressed form of the packet, the context can		details below. In the compressed form of the packet, the context can
	be signaled in by the InstanceID in the RPI.		be signaled in by the RPLInstanceID in the RPI.
	With RPL [RFC6550], the address of DODAG root is known from the		With RPL [RFC6550], the address of the DODAG root is known from the
	DODAGID field of the DIO messages. For a Global Instance, the		DODAGID field of the DIO messages. For a Global Instance, the
	RPLInstanceID that is present in the RPI is enough information to		RPLInstanceID that is present in the RPI is enough information to
	identify the DODAG that this node participates to and its associated		identify the DODAG that this node participates to and its associated
	root. But for a Local Instance, the address of the root MUST be		root. But for a Local Instance, the address of the root MUST be
	explicit, either in some device configuration or signaled in the		explicit, either in some device configuration or signaled in the
	packet, as the source or the destination address, respectively.		packet, as the source or the destination address, respectively.
	When implicit, the address of the DODAG root MUST be determined as		When implicit, the address of the DODAG root MUST be determined as
	follows:		follows:
	If the whole network is a single DODAG then the root can be well-		If the whole network is a single DODAG then the root can be well-
	known and does not need to be signaled in the packets. But RPL does		known and does not need to be signaled in the packets. But since RPL
	not expose that property and it can only be known by a configuration		does not expose that property, it can only be known by a
	applied to all nodes.		configuration applied to all nodes.
	Else, the router that encapsulates the packet and compresses it with		Else, the router that encapsulates the packet and compresses it with
	this specification MUST also place an RPI in the packet as prescribed		this specification MUST also place an RPI in the packet as prescribed
	by [RFC6550] to enable the identification of the DODAG. The RPI must		by [RFC6550] to enable the identification of the DODAG. The RPI must
	be present even in the case when the router also places an RH3 header		be present even in the case when the router also places an SRH header
	in the packet.		in the packet.
	It is expected that the RPL implementation provides an abstract		It is expected that the RPL implementation maintains an abstract
	context table, indexed by Global RPLInstanceID, that provides the		context table, indexed by Global RPLInstanceID, that provides the
	address of the root of the DODAG that this nodes participates to for		address of the root of the DODAG that this nodes participates to for
	that particular Instance.		that particular RPL Instance.
	5. The Routing Header Type 3 (RH3) 6LoRH Header		5. The SRH 6LoRH Header
	## Encoding {#RH3-6LoRH-encoding}		5.1. Encoding
	The Routing Header type 3 (RH3) 6LoRH (RH3-6LoRH) header is a		The Source Routing Header 6LoRH (SRH-6LoRH) header is a Critical
	Critical 6LoWPAN Routing Header that provides a compressed form for		6LoWPAN Routing Header that provides a compressed form for the SRH,
	the RH3, as defined in [RFC6554] for use by RPL routers. Routers		as defined in [RFC6554] for use by RPL routers. Routers that need to
	that need to forward a packet with a RH3-6LoRH are expected to be RPL		forward a packet with a SRH-6LoRH are expected to be RPL routers and
	routers and are expected to support this specification. If a non-RPL		are expected to support this specification. If a non-RPL router
	router receives a packet with a RH3-6LoRH, this means that there was		receives a packet with a SRH-6LoRH, this means that there was a
	a routing error and the packet should be dropped so the Type cannot		routing error and the packet should be dropped so the Type cannot be
	be ignored.		ignored.
	0 1		0 1
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- -+- -+ ... +- -+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- -+- -+ ... +- -+
	|1|0|0| Size |6LoRH Type 0..4| Hop1 | Hop2 | | HopN |		|1|0|0| Size |6LoRH Type 0..4| Hop1 | Hop2 | | HopN |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- -+- -+ ... +- -+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- -+- -+ ... +- -+
	Size indicates the number of compressed addresses		Size indicates the number of compressed addresses
	Figure 6: The RH3-6LoRH.		Figure 6: The SRH-6LoRH.
	The 6LoRH Type indicates the compression level used in a given		The 6LoRH Type indicates the compression level used in a given SRH-
	RH3-6LoRH header.		6LoRH header.
	One or more 6LoRH header(s) MAY be placed in a 6LoWPAN packet.		One or more 6LoRH header(s) MAY be placed in a 6LoWPAN packet.
	It results that all addresses in a given RH3-6LoRH header MUST be		It results that all addresses in a given SRH-6LoRH header MUST be
	compressed in an identical fashion, down to using the identical		compressed in an identical fashion, down to using the identical
	number of bytes per address. In order to get different degrees of		number of bytes per address. In order to get different degrees of
	compression, multiple consecutive RH3-6LoRH headers MUST be used.		compression, multiple consecutive SRH-6LoRH headers MUST be used.
	Type 0 means that the address is compressed down to one byte, whereas		Type 0 means that the address is compressed down to one byte, whereas
	Type 4 means that the address is provided in full in the RH3-6LoRH		Type 4 means that the address is provided in full in the SRH-6LoRH
	with no compression. The complete list of Types of RH3-6LoRH and the		with no compression. The complete list of Types of SRH-6LoRH and the
	corresponding compression level are provided in Figure 7:		corresponding compression level are provided in Figure 7:
	+-----------+----------------------+		+-----------+----------------------+
	| 6LoRH | Length of compressed |		| 6LoRH | Length of compressed |
	| Type | IPv6 address (bytes) |		| Type | IPv6 address (bytes) |
	+-----------+----------------------+		+-----------+----------------------+
	| 0 | 1 |		| 0 | 1 |
	| 1 | 2 |		| 1 | 2 |
	| 2 | 4 |		| 2 | 4 |
	| 3 | 8 |		| 3 | 8 |
	| 4 | 16 |		| 4 | 16 |
	+-----------+----------------------+		+-----------+----------------------+
	Figure 7: The RH3-6LoRH Types.		Figure 7: The SRH-6LoRH Types.
	In the case of a RH3-6LoRH header, the TSE field is used as a Size,		In the case of a SRH-6LoRH header, the TSE field is used as a Size,
	which encodes the number of hops minus 1; so a Size of 0 means one		which encodes the number of hops minus 1; so a Size of 0 means one
	hop, and the maximum that can be encoded is 32 hops. (If more than		hop, and the maximum that can be encoded is 32 hops. (If more than
	32 hops need to be expressed, a sequence of RH3-6LoRH elements can be		32 hops need to be expressed, a sequence of SRH-6LoRH elements can be
	employed.) It results that the Length in bytes of a RH3-6LoRH header		employed.) It results that the Length in bytes of a SRH-6LoRH header
	is:		is:
	2 + Length_of_compressed_IPv6_address * (Size + 1)		2 + Length_of_compressed_IPv6_address * (Size + 1)
	5.1. RH3-6LoRH General Operation		5.2. SRH-6LoRH General Operation
			5.2.1. Uncompressed SRH Operation
	In the non-compressed form, when the root generates or forwards a		In the non-compressed form, when the root generates or forwards a
	packet in non-Storing Mode, it needs to include a Routing Header type		packet in non-Storing Mode, it needs to include a Source Routing
	3 (RH3) [RFC6554] to signal a strict source-route path to a final		Header [RFC6554] to signal a strict source-route path to a final
	destination down the DODAG. All the hops along the path, but the		destination down the DODAG.
	first one, are encoded in order in the RH3. The last entry in the
	RH3 is the final destination and the destination in the IPv6 header
	is the first hop along the source-route path. The intermediate hops
	perform a swap and the Segment-Left field indicates the active entry
	in the Routing Header [RFC2460]. The current destination of the
	packet, which is the termination of the current segment, is indicated
	at all times by the destination address of the IPv6 header.
	The handling of the RH3-6LoRH is different: there is no swap, and a		All the hops along the path, but the first one, are encoded in order
			in the SRH. The last entry in the SRH is the final destination and
			the destination in the IPv6 header is the first hop along the source-
			route path. The intermediate hops perform a swap and the Segment-
			Left field indicates the active entry in the Routing Header
			[RFC2460].
			The current destination of the packet, which is the termination of
			the current segment, is indicated at all times by the destination
			address of the IPv6 header.
			5.2.2. 6LoRH-Compressed SRH Operation
			The handling of the SRH-6LoRH is different: there is no swap, and a
	forwarding router that corresponds to the first entry in the first		forwarding router that corresponds to the first entry in the first
	RH3-6LoRH upon reception of a packet effectively consumes that entry		SRH-6LoRH upon reception of a packet effectively consumes that entry
	when forwarding. This means that the size of a compressed source-		when forwarding. This means that the size of a compressed source-
	routed packet decreases as the packet progresses along its path and		routed packet decreases as the packet progresses along its path and
	that the routing information is lost along the way. This also means		that the routing information is lost along the way. This also means
	that an RH3 encoded with 6LoRH is not recoverable and cannot be		that an SRH encoded with 6LoRH is not recoverable and cannot be
	protected.		protected.
	When compressed with this specification, all the remaining hops MUST		When compressed with this specification, all the remaining hops MUST
	be encoded in order in one or more consecutive RH3-6LoRH headers.		be encoded in order in one or more consecutive SRH-6LoRH headers.
	Whether or not there is a RH3-6LoRH header present, the address of		Whether or not there is a SRH-6LoRH header present, the address of
	the final destination is indicated in the LoWPAN_IPHC at all times		the final destination is indicated in the LoWPAN_IPHC at all times
	along the path. Examples of this are provided in Appendix A.		along the path. Examples of this are provided in Appendix A.
	The current destination (termination of the current segment) for a		The current destination (termination of the current segment) for a
	compressed source-routed packet is indicated in the first entry of		compressed source-routed packet is indicated in the first entry of
	the first RH3-6LoRH. In strict source-routing, that entry MUST match		the first SRH-6LoRH. In strict source-routing, that entry MUST match
	an address of the router that receives the packet.		an address of the router that receives the packet.
	The last entry in the last RH3-6LoRH is the last router on the way to		The last entry in the last SRH-6LoRH is the last router on the way to
	the final destination in the LLN. It is typically a RPL parent of		the final destination in the LLN. This router can be the final
	the final destination, but it can also be a router acting at 6LR		destination if it is found desirable to carry a whole IP-in-IP
	[RFC6775] for the destination host.		encapsulation all the way. Else, it is the RPL parent of the final
			destination, or a router acting at 6LR [RFC6775] for the destination
			host, and advertising the host as an external route to RPL.
	5.2. The Design Point of Popping Entries		If the SRH-6LoRH header is contained in an IP-in-IP encapsulation,
			the last router removes the whole chain of headers. Otherwise, it
			removes the SRH-6LoRH header only.
			5.2.3. Inner LOWPAN_IPHC Compression
			6LoWPAN ND [RFC6282] is designed to support more than one IPv6
			address per node and per Interface Identifier (IID), an IID being
			typically derived from a MAC address to optimize the LOWPAN-IPHC
			compression.
			Link local addresses are compressed with stateless address
			compression (S/DAC=0). The other addresses are derived from
			different prefixes and they can be compressed with stateful address
			compression based on a context (S/DAC=1).
			But stateless compression is only defined for the specific link-local
			prefix as opposed to the prefix in an encapsulating header. And with
			stateful compression, the compression reference is found in a
			context, as opposed to an encapsulating header.
			It results that in the case of an IP-in-IP encapsulation, it is
			possible to compress an inner source (respectively destination) IP
			address in a LOWPAN_IPHC based on the encapsulating IP header only if
			stateful (context-based) compression is used. The compression will
			operate only if the IID in the source (respectively the destination)
			IP address in the outer and inner headers match, which usually means
			that they refer to the same node . This is encoded as S/DAC = 1 and
			S/AM=11. It must be noted that the outer destination address that is
			used to compress the inner destination address is the last entry in
			the last SRH-6LoRH header.
			5.3. The Design Point of Popping Entries
	In order to save energy and to optimize the chances of transmission		In order to save energy and to optimize the chances of transmission
	success on lossy media, it is a design point for this specification		success on lossy media, it is a design point for this specification
	that the entries in the RH3 that have been used are removed from the		that the entries in the SRH that have been used are removed from the
	packet. This creates a discrepancy from the art of IPv6 where		packet. This creates a discrepancy from the art of IPv6 where
	Routing Header are mutable but recoverable.		Routing Header are mutable but recoverable.
	With this specification, the packet can be expanded at any hop into a		With this specification, the packet can be expanded at any hop into a
	valid IPv6 packet, including a RH3, and compressed back. But the		valid IPv6 packet, including a SRH, and compressed back. But the
	packet as decompressed along the way will not carry all the consumed		packet as decompressed along the way will not carry all the consumed
	addresses that packet would have if it had been forwarded in the		addresses that packet would have if it had been forwarded in the
	uncompressed form.		uncompressed form.
	It is noted that:		It is noted that:
	The value of keeping the whole RH in an IPv6 header is for the		The value of keeping the whole RH in an IPv6 header is for the
	receiver to reverse it to use the symmetrical path on the way		receiver to reverse it to use the symmetrical path on the way
	back.		back.
	skipping to change at page 1, line 632 ¶		skipping to change at page 1, line 681 ¶
	There is no use of reversing a RH in the present RPL		There is no use of reversing a RH in the present RPL
	specifications.		specifications.
	P2P RPL reverses a path that was learned reactively, as a part of		P2P RPL reverses a path that was learned reactively, as a part of
	the protocol operation, which is probably a cleaner way than a		the protocol operation, which is probably a cleaner way than a
	reversed echo on the data path.		reversed echo on the data path.
	Reversing a header is discouraged by [RFC2460] for RH0 unless it		Reversing a header is discouraged by [RFC2460] for RH0 unless it
	is authenticated, which requires an Authentication Header (AH).		is authenticated, which requires an Authentication Header (AH).
	There is no definition of an AH operation for RH3, and there is no		There is no definition of an AH operation for SRH, and there is no
	indication that the need exists in LLNs.		indication that the need exists in LLNs.
	It is noted that AH does not protect the RH on the way. AH is a		It is noted that AH does not protect the RH on the way. AH is a
	validation at the receiver with the sole value of enabling the		validation at the receiver with the sole value of enabling the
	receiver to reversing it.		receiver to reversing it.
	A RPL domain is usually protected by L2 security and that secures		A RPL domain is usually protected by L2 security and that secures
	both RPL itself and the RH in the packets, at every hop. This is		both RPL itself and the RH in the packets, at every hop. This is
	a better security than that provided by AH.		a better security than that provided by AH.
	In summary, the benefit of saving energy and lowering the chances of		In summary, the benefit of saving energy and lowering the chances of
	loss by sending smaller frames over the LLN are seen as overwhelming		loss by sending smaller frames over the LLN are seen as overwhelming
	compared to the value of possibly reversing the header.		compared to the value of possibly reversing the header.
	5.3. Compression Reference		5.4. Compression Reference for SRH-6LoRH header entries
	In order to optimize the compression of IP addresses present in the		In order to optimize the compression of IP addresses present in the
	RH3 headers, this specification requires that the 6LoWPAN layer		SRH headers, this specification requires that the 6LoWPAN layer
	identifies an address that is used as reference for the compression.		identifies an address that is used as reference for the compression.
	With this specification, the Compression Reference for addresses
	found in an RH3 header is the source of the IPv6 packet.
	With RPL [RFC6550], an RH3 header may only be present in Non-Storing		With this specification, the Compression Reference for the first
			address found in an SRH header is the source of the IPv6 packet, and
			then the reference for each subsequent entry is the address of its
			predecessor once it is uncompressed.
			With RPL [RFC6550], an SRH header may only be present in Non-Storing
	mode, and it may only be placed in the packet by the root of the		mode, and it may only be placed in the packet by the root of the
	DODAG, which must be the source of the resulting IPv6 packet		DODAG, which must be the source of the resulting IPv6 packet
	[RFC2460]. In this case, the address used as Compression Reference		[RFC2460]. In this case, the address used as Compression Reference
	is that the address of the root, and it can be implicit when the		is that the address of the root, and it can be implicit when the
	address of the root is.		address of the root is.
	The Compression Reference MUST be determined as follows:		The Compression Reference MUST be determined as follows:
	The reference address may be obtained by configuration. The		The reference address may be obtained by configuration. The
	configuration may indicate either the address in full, or the		configuration may indicate either the address in full, or the
	skipping to change at page 1, line 678 ¶		skipping to change at page 1, line 730 ¶
	[RFC6282].		[RFC6282].
	Else, and if there is no IP-in-IP encapsulation, the source address		Else, and if there is no IP-in-IP encapsulation, the source address
	in the IPv6 header that is compressed with LOWPAN-IPHC is the		in the IPv6 header that is compressed with LOWPAN-IPHC is the
	reference for the compression.		reference for the compression.
	Else, and if the IP-in-IP compression specified in this document is		Else, and if the IP-in-IP compression specified in this document is
	used and the Encapsulator Address is provided, then the Encapsulator		used and the Encapsulator Address is provided, then the Encapsulator
	Address is the reference.		Address is the reference.
	5.4. Popping Headers		5.5. Popping Headers
	Upon reception, the router checks whether the address in the first		Upon reception, the router checks whether the address in the first
	entry of the first RH3-6LoRH one of its own addresses. In that case,		entry of the first SRH-6LoRH one of its own addresses. In that case,
	router MUST consume that entry before forwarding, which is an action		router MUST consume that entry before forwarding, which is an action
	of popping from a stack, where the stack is effectively the sequence		of popping from a stack, where the stack is effectively the sequence
	of entries in consecutive RH3-6LoRH headers.		of entries in consecutive SRH-6LoRH headers.
	Popping an entry of an RH3-6LoRH header is a recursive action		Popping an entry of an SRH-6LoRH header is a recursive action
	performed as follows:		performed as follows:
	If the Size of the RH3-6LoRH header is 1 or more, indicating that		If the Size of the SRH-6LoRH header is 1 or more, indicating that
	there are at least 2 entries in the header, the router removes the		there are at least 2 entries in the header, the router removes the
	first entry and decrements the Size (by 1).		first entry and decrements the Size (by 1).
	Else (meaning that this is the last entry in the RH3-6LoRH header),		Else (meaning that this is the last entry in the SRH-6LoRH header),
	and if there is no next RH3-6LoRH header after this then the		and if there is no next SRH-6LoRH header after this then the SRH-
	RH3-6LoRH is removed.		6LoRH is removed.
	Else, if there is a next RH3-6LoRH of a Type with a larger or equal		Else, if there is a next SRH-6LoRH of a Type with a larger or equal
	value, meaning a same or lesser compression yielding same or larger		value, meaning a same or lesser compression yielding same or larger
	compressed forms, then the RH3-6LoRH is removed.		compressed forms, then the SRH-6LoRH is removed.
	Else, the first entry of the next RH3-6LoRH is popped from the next		Else, the first entry of the next SRH-6LoRH is popped from the next
	RH3-6LoRH and coalesced with the first entry of this RH3-6LoRH.		SRH-6LoRH and coalesced with the first entry of this SRH-6LoRH.
	At the end of the process, if there is no more RH3-6LoRH in the		At the end of the process, if there is no more SRH-6LoRH in the
	packet, then the processing node is the last router along the source		packet, then the processing node is the last router along the source
	route path.		route path.
	5.5. Forwarding		5.6. Forwarding
	When receiving a packet with a RH3-6LoRH, a router determines the		When receiving a packet with a SRH-6LoRH, a router determines the
	IPv6 address of the current segment endpoint.		IPv6 address of the current segment endpoint.
	If strict source routing is enforced and thus router is not the		If strict source routing is enforced and thus router is not the
	segment endpoint for the packet then this router MUST drop the		segment endpoint for the packet then this router MUST drop the
	packet.		packet.
	If this router is the current segment endpoint, then the router pops		If this router is the current segment endpoint, then the router pops
	its address as described in Section 5.4 and continues processing the		its address as described in Section 5.5 and continues processing the
	packet.		packet.
	If there is still a RH3-6LoRH, then the router determines the new		If there is still a SRH-6LoRH, then the router determines the new
	segment endpoint and routes the packet towards that endpoint.		segment endpoint and routes the packet towards that endpoint.
	Otherwise the router uses the destination in the inner IP header to		Otherwise the router uses the destination in the inner IP header to
	forward or accept the packet.		forward or accept the packet.
	The segment endpoint of a packet MUST be determined as follows:		The segment endpoint of a packet MUST be determined as follows:
	The router first determines the Compression Reference as discussed in		The router first determines the Compression Reference as discussed in
	Section 4.3.1.		Section 4.3.1.
	The router then coalesces the Compression Reference with the first		The router then coalesces the Compression Reference with the first
	entry of the first RH3-6LoRH header as discussed in Section 5.3. If		entry of the first SRH-6LoRH header as discussed in Section 5.4. If
	the type of the RH3-6LoRH header is type 4 then the coalescence is a		the type of the SRH-6LoRH header is type 4 then the coalescence is a
	full override.		full override.
	Since the Compression Reference is an uncompressed address, the		Since the Compression Reference is an uncompressed address, the
	coalesced IPv6 address is also expressed in the full 128bits.		coalesced IPv6 address is also expressed in the full 128bits.
	An example of this operation is provided in Appendix A.3.		An example of this operation is provided in Appendix A.3.
	6. The RPL Packet Information 6LoRH		6. The RPL Packet Information 6LoRH
	[RFC6550], Section 11.2, specifies the RPL Packet Information (RPI)		[RFC6550], Section 11.2, specifies the RPL Packet Information (RPI)
	as a set of fields that are placed by RPL routers in IP packets for		as a set of fields that are placed by RPL routers in IP packets to
	the purpose of Instance Identification, as well as Loop Avoidance and		identify the RPL Instance, detect anomalies and trigger corrective
	Detection.		actions.
	In particular, the SenderRank, which is the scalar metric computed by		In particular, the SenderRank, which is the scalar metric computed by
	a specialized Objective Function such as [RFC6552], indicates the		a specialized Objective Function such as [RFC6552], indicates the
	Rank of the sender and is modified at each hop. The SenderRank field		Rank of the sender and is modified at each hop. The SenderRank field
	is used to validate that the packet progresses in the expected		is used to validate that the packet progresses in the expected
	direction, either upwards or downwards, along the DODAG.		direction, either upwards or downwards, along the DODAG.
	RPL defines the RPL Option for Carrying RPL Information in Data-Plane		RPL defines the RPL Option for Carrying RPL Information in Data-Plane
	Datagrams [RFC6553] to transport the RPI, which is carried in an IPv6		Datagrams [RFC6553] to transport the RPI, which is carried in an IPv6
	Hop-by-Hop Options Header [RFC2460], typically consuming eight bytes		Hop-by-Hop Options Header [RFC2460], typically consuming eight bytes
	skipping to change at page 1, line 789 ¶		skipping to change at page 1, line 841 ¶
	domain.		domain.
	For that reason, this specification defines an IP-in-IP-6LoRH header		For that reason, this specification defines an IP-in-IP-6LoRH header
	in Section 7, but it must be noted that removal of a 6LoRH header		in Section 7, but it must be noted that removal of a 6LoRH header
	does not require manipulation of the packet in the LOWPAN_IPHC, and		does not require manipulation of the packet in the LOWPAN_IPHC, and
	thus, if the source address in the LOWPAN_IPHC is the node that		thus, if the source address in the LOWPAN_IPHC is the node that
	inserted the IP-in-IP-6LoRH header then this situation alone does not		inserted the IP-in-IP-6LoRH header then this situation alone does not
	mandate an IP-in-IP-6LoRH header.		mandate an IP-in-IP-6LoRH header.
	Note: A typical packet in RPL non-storing mode going down the RPL		Note: A typical packet in RPL non-storing mode going down the RPL
	graph requires an IP-in-IP encapsulation of the RH3, whereas the RPI		graph requires an IP-in-IP encapsulation of the SRH, whereas the RPI
	is usually (and quite illegally) omitted, unless it is important to		is usually (and quite illegally) omitted, unless it is important to
	indicate the RPLInstanceID. To match this structure, an optimized		indicate the RPLInstanceID. To match this structure, an optimized
	IP-in-IP 6LoRH header is defined in Section 7.		IP-in-IP 6LoRH header is defined in Section 7.
	As a result, a RPL packet may bear only an RPI-6LoRH header and no		As a result, a RPL packet may bear only an RPI-6LoRH header and no
	IP-in-IP-6LoRH header. In that case, the source and destination of		IP-in-IP-6LoRH header. In that case, the source and destination of
	the packet are specified by the LOWPAN_IPHC.		the packet are specified by the LOWPAN_IPHC.
	As with [RFC6553], the fields in the RPI include an 'O', an 'R', and		As with [RFC6553], the fields in the RPI include an 'O', an 'R', and
	an 'F' bit, an 8-bit RPLInstanceID (with some internal structure),		an 'F' bit, an 8-bit RPLInstanceID (with some internal structure),
	and a 16-bit SenderRank.		and a 16-bit SenderRank.
	The remainder of this section defines the RPI-6LoRH header, which is		The remainder of this section defines the RPI-6LoRH header, which is
	a Critical 6LoWPAN Routing Header that is designed to transport the		a Critical 6LoWPAN Routing Header that is designed to transport the
	RPI in 6LoWPAN LLNs.		RPI in 6LoWPAN LLNs.
	6.1. Compressing the RPLInstanceID		6.1. Compressing the RPLInstanceID
	RPL Instances are discussed in [RFC6550], Section 5. A number of		RPL Instances are discussed in [RFC6550], Section 5. A number of
	simple use cases do not require more than one instance, and in such		simple use cases do not require more than one RPL Instance, and in
	cases, the instance is expected to be the global Instance 0. A		such cases, the RPL Instance is expected to be the Global Instance 0.
	global RPLInstanceID is encoded in a RPLInstanceID field as follows:		A global RPLInstanceID is encoded in a RPLInstanceID field as
			follows:
	0 1 2 3 4 5 6 7		0 1 2 3 4 5 6 7
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	|0| ID | Global RPLInstanceID in 0..127		|0| ID | Global RPLInstanceID in 0..127
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	Figure 8: RPLInstanceID Field Format for Global Instances.		Figure 8: RPLInstanceID Field Format for Global Instances.
	For the particular case of the global Instance 0, the RPLInstanceID		For the particular case of the Global Instance 0, the RPLInstanceID
	field is all zeros. This specification allows to elide a		field is all zeros. This specification allows to elide a
	RPLInstanceID field that is all zeros, and defines a I flag that,		RPLInstanceID field that is all zeros, and defines a I flag that,
	when set, signals that the field is elided.		when set, signals that the field is elided.
	6.2. Compressing the SenderRank		6.2. Compressing the SenderRank
	The SenderRank is the result of the DAGRank operation on the rank of		The SenderRank is the result of the DAGRank operation on the rank of
	the sender; here the DAGRank operation is defined in [RFC6550],		the sender; here the DAGRank operation is defined in [RFC6550],
	Section 3.5.1, as:		Section 3.5.1, as:
	skipping to change at page 1, line 879 ¶		skipping to change at page 1, line 932 ¶
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... -+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... -+-+-+
	|1|0|0|O|R|F|I|K| 6LoRH Type=5 | Compressed fields |		|1|0|0|O|R|F|I|K| 6LoRH Type=5 | Compressed fields |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... -+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... -+-+-+
	Figure 9: The Generic RPI-6LoRH Format.		Figure 9: The Generic RPI-6LoRH Format.
	O, R, and F bits: The O, R, and F bits are defined in [RFC6550],		O, R, and F bits: The O, R, and F bits are defined in [RFC6550],
	section 11.2.		section 11.2.
	I bit: If it is set, the Instance ID is elided and the RPLInstanceID		I bit: If it is set, the RPLInstanceID is elided and the
	is the Global RPLInstanceID 0. If it is not set, the octet		RPLInstanceID is the Global RPLInstanceID 0. If it is not set,
	immediately following the type field contains the RPLInstanceID		the octet immediately following the type field contains the
	as specified in [RFC6550], section 5.1.		RPLInstanceID as specified in [RFC6550], section 5.1.
	K bit: If it is set, the SenderRank is compressed into one octet,		K bit: If it is set, the SenderRank is compressed into one octet,
	with the least significant octet elided. If it is not set, the		with the least significant octet elided. If it is not set, the
	SenderRank, is fully inlined as two octets.		SenderRank, is fully inlined as two octets.
	In Figure 10, the RPLInstanceID is the Global RPLInstanceID 0, and		In Figure 10, the RPLInstanceID is the Global RPLInstanceID 0, and
	the MinHopRankIncrease is a multiple of 256 so the least significant		the MinHopRankIncrease is a multiple of 256 so the least significant
	byte is all zeros and can be elided:		byte is all zeros and can be elided:
	0 1 2		0 1 2
	skipping to change at page 1, line 976 ¶		skipping to change at page 1, line 1029 ¶
	The Length of an IP-in-IP-6LoRH header is expressed in bytes and MUST		The Length of an IP-in-IP-6LoRH header is expressed in bytes and MUST
	be at least 1, to indicate a Hop Limit (HL), that is decremented at		be at least 1, to indicate a Hop Limit (HL), that is decremented at
	each hop. When the HL reaches 0, the packet is dropped per		each hop. When the HL reaches 0, the packet is dropped per
	[RFC2460].		[RFC2460].
	If the Length of an IP-in-IP-6LoRH header is exactly 1, then the		If the Length of an IP-in-IP-6LoRH header is exactly 1, then the
	Encapsulator Address is elided, which means that the Encapsulator is		Encapsulator Address is elided, which means that the Encapsulator is
	a well-known router, for instance the root in a RPL graph.		a well-known router, for instance the root in a RPL graph.
	With this specification, an optimal compression of IP-in-IP		The most efficient compression of an IP-in-IP encapsulation that can
	encapsulation can be achieved if an endpoint of the packet is the		be achieved with this specification is obtained when an endpoint of
	root of the RPL DODAG associated to the Instance that is used to		the packet is the root of the RPL DODAG associated to the RPL
	forward the packet, and the root address is known implicitly as		Instance that is used to forward the packet, and the root address is
	opposed to signaled explicitly in the data packets.		known implicitly as opposed to signaled explicitly in the data
			packets.
	If the Length of an IP-in-IP-6LoRH header is greater than 1, then an		If the Length of an IP-in-IP-6LoRH header is greater than 1, then an
	Encapsulator Address is placed in a compressed form after the Hop		Encapsulator Address is placed in a compressed form after the Hop
	Limit field. The value of the Length indicates which compression is		Limit field. The value of the Length indicates which compression is
	performed on the Encapsulator Address. For instance, a Size of 3		performed on the Encapsulator Address. For instance, a Size of 3
	indicates that the Encapsulator Address is compressed to 2 bytes.		indicates that the Encapsulator Address is compressed to 2 bytes.
	The reference for the compression is the address of the root of the		The reference for the compression is the address of the root of the
	DODAG. The way the address of the root is determined is discussed in		DODAG. The way the address of the root is determined is discussed in
	Section 4.3.2.		Section 4.3.2.
	When it cannot be elided, the destination IP address of the IP-in-IP
	header is transported in a RH3-6LoRH header as the first address of
	the list.
	With RPL, the destination address in the IP-in-IP header is		With RPL, the destination address in the IP-in-IP header is
	implicitly the root in the RPL graph for packets going upwards, and		implicitly the root in the RPL graph for packets going upwards, and,
	the destination address in the IPHC for packets going downwards. If		in storing mode, it is the destination address in the IPHC for
	the implicit value is correct, the destination IP address of the IP-		packets going downwards. In non-storing mode, there is no implicit
	in-IP encapsulation can be elided.		value for packets going downwards.
			If the implicit value is correct, the destination IP address of the
			IP-in-IP encapsulation can be elided. Else, the destination IP
			address of the IP-in-IP header is transported in a SRH-6LoRH header
			as the first entry of the first of these headers.
	If the final destination of the packet is a leaf that does not		If the final destination of the packet is a leaf that does not
	support this specification, then the chain of 6LoRH headers must be		support this specification, then the chain of 6LoRH headers must be
	stripped by the RPL/6LR router to which the leaf is attached. In		stripped by the RPL/6LR router to which the leaf is attached. In
	that example, the destination IP address of the IP-in-IP header		that example, the destination IP address of the IP-in-IP header
	cannot be elided.		cannot be elided.
	In the special case where a 6LoRH header is used to route 6LoWPAN		In the special case where a 6LoRH header is used to route 6LoWPAN
	fragments, the destination address is not accessible in the IPHC on		fragments, the destination address is not accessible in the IPHC on
	all fragments and can be elided only for the first fragment and for		all fragments and can be elided only for the first fragment and for
	skipping to change at page 23, line 10 ¶		skipping to change at page 24, line 10 ¶
	101xxxxx: for Elective 6LoWPAN Routing Headers		101xxxxx: for Elective 6LoWPAN Routing Headers
	100xxxxx: for Critical 6LoWPAN Routing Headers.		100xxxxx: for Critical 6LoWPAN Routing Headers.
	9.2. New 6LoWPAN Routing Header Type Registry		9.2. New 6LoWPAN Routing Header Type Registry
	This document creates an IANA registry for the 6LoWPAN Routing Header		This document creates an IANA registry for the 6LoWPAN Routing Header
	Type, and assigns the following values:		Type, and assigns the following values:
	0..4: RH3-6LoRH [RFCthis]		0..4: SRH-6LoRH [RFCthis]
	5: RPI-6LoRH [RFCthis]		5: RPI-6LoRH [RFCthis]
	6: IP-in-IP-6LoRH [RFCthis]		6: IP-in-IP-6LoRH [RFCthis]
	10. Acknowledgments		10. Acknowledgments
	The authors wish to thank Tom Phinney, Thomas Watteyne, Tengfei		The authors wish to thank Tom Phinney, Thomas Watteyne, Tengfei
	Chang, Martin Turon, James Woodyatt, Samita Chakrabarti, Jonathan		Chang, Martin Turon, James Woodyatt, Samita Chakrabarti, Jonathan
	Hui, Gabriel Montenegro and Ralph Droms for constructive reviews to		Hui, Gabriel Montenegro and Ralph Droms for constructive reviews to
	skipping to change at page 23, line 43 ¶		skipping to change at page 24, line 43 ¶
	Thubert, P., "6LoWPAN Paging Dispatch", draft-ietf-6lo-		Thubert, P., "6LoWPAN Paging Dispatch", draft-ietf-6lo-
	paging-dispatch-01 (work in progress), January 2016.		paging-dispatch-01 (work in progress), January 2016.
	[IEEE802154]		[IEEE802154]
	IEEE standard for Information Technology, "IEEE std.		IEEE standard for Information Technology, "IEEE std.
	802.15.4, Part. 15.4: Wireless Medium Access Control (MAC)		802.15.4, Part. 15.4: Wireless Medium Access Control (MAC)
	and Physical Layer (PHY) Specifications for Low-Rate		and Physical Layer (PHY) Specifications for Low-Rate
	Wireless Personal Area Networks", 2015.		Wireless Personal Area Networks", 2015.
	[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/
	DOI 10.17487/RFC2119, March 1997,		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, DOI 10.17487/RFC2460,
	December 1998, <http://www.rfc-editor.org/info/rfc2460>.		December 1998, <http://www.rfc-editor.org/info/rfc2460>.
	[RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler,		[RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler,
	"Transmission of IPv6 Packets over IEEE 802.15.4		"Transmission of IPv6 Packets over IEEE 802.15.4
	Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007,		Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007,
	<http://www.rfc-editor.org/info/rfc4944>.		<http://www.rfc-editor.org/info/rfc4944>.
	[RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6		[RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6
	Datagrams over IEEE 802.15.4-Based Networks", RFC 6282,		Datagrams over IEEE 802.15.4-Based Networks", RFC 6282,
	DOI 10.17487/RFC6282, September 2011,		DOI 10.17487/RFC6282, September 2011,
	<http://www.rfc-editor.org/info/rfc6282>.		<http://www.rfc-editor.org/info/rfc6282>.
	[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/
	DOI 10.17487/RFC6550, March 2012,		RFC6550, March 2012,
	<http://www.rfc-editor.org/info/rfc6550>.		<http://www.rfc-editor.org/info/rfc6550>.
	[RFC6552] Thubert, P., Ed., "Objective Function Zero for the Routing		[RFC6552] Thubert, P., Ed., "Objective Function Zero for the Routing
	Protocol for Low-Power and Lossy Networks (RPL)",		Protocol for Low-Power and Lossy Networks (RPL)", RFC
	RFC 6552, DOI 10.17487/RFC6552, March 2012,		6552, DOI 10.17487/RFC6552, March 2012,
	<http://www.rfc-editor.org/info/rfc6552>.		<http://www.rfc-editor.org/info/rfc6552>.
	[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
	Information in Data-Plane Datagrams", RFC 6553,		Information in Data-Plane Datagrams", RFC 6553, DOI
	DOI 10.17487/RFC6553, March 2012,		10.17487/RFC6553, March 2012,
	<http://www.rfc-editor.org/info/rfc6553>.		<http://www.rfc-editor.org/info/rfc6553>.
	[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
	DOI 10.17487/RFC6554, March 2012,		10.17487/RFC6554, March 2012,
	<http://www.rfc-editor.org/info/rfc6554>.		<http://www.rfc-editor.org/info/rfc6554>.
	[RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and		[RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and
	Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January		Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January
	2014, <http://www.rfc-editor.org/info/rfc7102>.		2014, <http://www.rfc-editor.org/info/rfc7102>.
	[RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for		[RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for
	Constrained-Node Networks", RFC 7228,		Constrained-Node Networks", RFC 7228, DOI 10.17487/
	DOI 10.17487/RFC7228, May 2014,		RFC7228, May 2014,
	<http://www.rfc-editor.org/info/rfc7228>.		<http://www.rfc-editor.org/info/rfc7228>.
	11.2. Informative References		11.2. Informative References
	[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-09 (work		of IEEE 802.15.4", draft-ietf-6tisch-architecture-09 (work
	in progress), November 2015.		in progress), November 2015.
	[I-D.robles-roll-useofrplinfo]		[I-D.robles-roll-useofrplinfo]
	skipping to change at page 25, line 22 ¶		skipping to change at page 26, line 22 ¶
	RFC 6553, 6554 and IPv6-in-IPv6", draft-robles-roll-		RFC 6553, 6554 and IPv6-in-IPv6", draft-robles-roll-
	useofrplinfo-02 (work in progress), October 2015.		useofrplinfo-02 (work in progress), October 2015.
	[I-D.thubert-6lo-forwarding-fragments]		[I-D.thubert-6lo-forwarding-fragments]
	Thubert, P. and J. Hui, "LLN Fragment Forwarding and		Thubert, P. and J. Hui, "LLN Fragment Forwarding and
	Recovery", draft-thubert-6lo-forwarding-fragments-02 (work		Recovery", draft-thubert-6lo-forwarding-fragments-02 (work
	in progress), November 2014.		in progress), November 2014.
	[RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C.		[RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C.
	Bormann, "Neighbor Discovery Optimization for IPv6 over		Bormann, "Neighbor Discovery Optimization for IPv6 over
	Low-Power Wireless Personal Area Networks (6LoWPANs)",		Low-Power Wireless Personal Area Networks (6LoWPANs)", RFC
	RFC 6775, DOI 10.17487/RFC6775, November 2012,		6775, DOI 10.17487/RFC6775, November 2012,
	<http://www.rfc-editor.org/info/rfc6775>.		<http://www.rfc-editor.org/info/rfc6775>.
	[RFC7554] Watteyne, T., Ed., Palattella, M., and L. Grieco, "Using		[RFC7554] Watteyne, T., Ed., Palattella, M., and L. Grieco, "Using
	IEEE 802.15.4e Time-Slotted Channel Hopping (TSCH) in the		IEEE 802.15.4e Time-Slotted Channel Hopping (TSCH) in the
	Internet of Things (IoT): Problem Statement", RFC 7554,		Internet of Things (IoT): Problem Statement", RFC 7554,
	DOI 10.17487/RFC7554, May 2015,		DOI 10.17487/RFC7554, May 2015,
	<http://www.rfc-editor.org/info/rfc7554>.		<http://www.rfc-editor.org/info/rfc7554>.
	Appendix A. Examples		Appendix A. Examples
	skipping to change at page 25, line 50 ¶		skipping to change at page 27, line 12 ¶
	fragmentation process takes place per [RFC4944], and the fragment		fragmentation process takes place per [RFC4944], and the fragment
	headers must be placed in Page 0 before switching to Page 1:		headers must be placed in Page 0 before switching to Page 1:
	+- ... -+- ... -+-+ ... -+- ... +-+-+ ... -+-+-+-+-+-+-+-+-+-+...		+- ... -+- ... -+-+ ... -+- ... +-+-+ ... -+-+-+-+-+-+-+-+-+-+...
	|Frag type|Frag hdr |11110001| RPI- |IP-in-IP| LOWPAN-IPHC | ...		|Frag type|Frag hdr |11110001| RPI- |IP-in-IP| LOWPAN-IPHC | ...
	|RFC 4944 |RFC 4944 | Page 1 | 6LoRH | 6LoRH | |		|RFC 4944 |RFC 4944 | Page 1 | 6LoRH | 6LoRH | |
	+- ... -+- ... -+-+ ... -+- ... +-+-+ ... -+-+-+-+-+-+-+-+-+-+...		+- ... -+- ... -+-+ ... -+- ... +-+-+ ... -+-+-+-+-+-+-+-+-+-+...
	<- RFC 6282 ->		<- RFC 6282 ->
	No RPL artifact		No RPL artifact
			+- ... -+- ... -+-+ ... -+-+ ... -+- ... +-+-+-+-+-+-+-+-+-+-+...
			|Frag type|Frag hdr |
			|RFC 4944 |RFC 4944 | Payload (cont)
			+- ... -+- ... -+-+ ... -+-+ ... -+- ... +-+-+-+-+-+-+-+-+-+-+...
			+- ... -+- ... -+-+ ... -+-+ ... -+- ... +-+-+-+-+-+-+-+-+-+-+...
			|Frag type|Frag hdr |
			|RFC 4944 |RFC 4944 | Payload (cont)
			+- ... -+- ... -+-+ ... -+-+ ... -+- ... +-+-+-+-+-+-+-+-+-+-+...
	Figure 15: Example Compressed Packet with RPI.		Figure 15: Example Compressed Packet with RPI.
	In Storing Mode, if the packet stays within the RPL domain, then it		In Storing Mode, if the packet stays within the RPL domain, then it
	is possible to save the IP-in-IP encapsulation, in which case only		is possible to save the IP-in-IP encapsulation, in which case only
	the RPI is compressed with a 6LoRH, as illustrated in Figure 16 in		the RPI is compressed with a 6LoRH, as illustrated in Figure 16 in
	the case of a non-fragmented ICMP packet:		the case of a non-fragmented ICMP packet:
	+- ... -+-+- ... -+-+-+-+ ... -+-+-+-+ ... -+-+-+-+-+-+-+-+-+-+-+...		+- ... -+-+- ... -+-+-+-+ ... -+-+-+-+ ... -+-+-+-+-+-+-+-+-+-+-+...
	|11110001| RPI-6LoRH | NH = 0 | NH = 58 | ICMP message ...		|11110001| RPI-6LoRH | NH = 0 | NH = 58 | ICMP message ...
	|Page 1 | type 5 | 6LOWPAN-IPHC | (ICMP) | (no compression)		|Page 1 | type 5 | 6LOWPAN-IPHC | (ICMP) | (no compression)
	skipping to change at page 27, line 21 ¶		skipping to change at page 28, line 34 ¶
	Figure 19: RPI inserted by the root in Storing Mode.		Figure 19: RPI inserted by the root in Storing Mode.
	A.2. Example Of Downward Packet In Non-Storing Mode		A.2. Example Of Downward Packet In Non-Storing Mode
	The example illustrated in Figure 20 is a classical packet in non-		The example illustrated in Figure 20 is a classical packet in non-
	Storing mode for a packet going down the DODAG following a source		Storing mode for a packet going down the DODAG following a source
	routed path from the root. Say that we have 4 forwarding hops to		routed path from the root. Say that we have 4 forwarding hops to
	reach a destination. In the non-compressed form, when the root		reach a destination. In the non-compressed form, when the root
	generates the packet, the last 3 hops are encoded in a Routing Header		generates the packet, the last 3 hops are encoded in a Routing Header
	type 3 (RH3) and the first hop is the destination of the packet. The		type 3 (SRH) and the first hop is the destination of the packet. The
	intermediate hops perform a swap and the hop count indicates the		intermediate hops perform a swap and the hop count indicates the
	current active hop [RFC2460], [RFC6554].		current active hop [RFC2460], [RFC6554].
	When compressed with this specification, the 4 hops are encoded in		When compressed with this specification, the 4 hops are encoded in
	RH3-6LoRH when the root generates the packet, and the final		SRH-6LoRH when the root generates the packet, and the final
	destination is left in the LOWPAN-IPHC. There is no swap, and the		destination is left in the LOWPAN-IPHC. There is no swap, and the
	forwarding node that corresponds to the first entry effectively		forwarding node that corresponds to the first entry effectively
	consumes it when forwarding, which means that the size of the encoded		consumes it when forwarding, which means that the size of the encoded
	packet decreases and that the hop information is lost.		packet decreases and that the hop information is lost.
	If the last hop in a RH3-6LoRH is not the final destination then it		If the last hop in a SRH-6LoRH is not the final destination then it
	removes the RH3-6LoRH before forwarding.		removes the SRH-6LoRH before forwarding.
	In the particular example illustrated in Figure 20, all addresses in		In the particular example illustrated in Figure 20, all addresses in
	the DODAG are assigned from a same /112 prefix and the last 2 octets		the DODAG are assigned from a same /112 prefix and the last 2 octets
	encoding an identifier such as a IEEE 802.15.4 short address. In		encoding an identifier such as a IEEE 802.15.4 short address. In
	that case, all addresses can be compressed to 2 octets, using the		that case, all addresses can be compressed to 2 octets, using the
	root address as reference. There will be one RH3_6LoRH header, with,		root address as reference. There will be one SRH_6LoRH header, with,
	in this example, 3 compressed addresses:		in this example, 3 compressed addresses:
	+-+-+-+-+-+-+- ... +-+-+- ... -+-+-- ... -+-+- ... -+-+-+-+-+ ... +-...		+-+-+-+-+-+-+- ... +-+-+- ... -+-+-- ... -+-+- ... -+-+-+-+-+ ... +-...
	|11110001 |RH3-6LoRH | RPI-6LoRH | IP-in-IP | NH=1 |11110CPP| UDP | UDP		|11110001 |SRH-6LoRH | RPI-6LoRH | IP-in-IP | NH=1 |11110CPP| UDP | UDP
	|Page 1 |Type1 S=2 | | 6LoRH | IPHC | UDP | hdr |load		|Page 1 |Type1 S=2 | | 6LoRH | IPHC | UDP | hdr |load
	+-+-+-+-+-+-+- ... +-+-+- ... -+-+-- ... -+-+- ... -+-+-+-+-+ ... +-...		+-+-+-+-+-+-+- ... +-+-+- ... -+-+-- ... -+-+- ... -+-+-+-+-+ ... +-...
	<-8bytes-> <- RFC 6282 ->		<-8bytes-> <- RFC 6282 ->
	No RPL artifact		No RPL artifact
	Figure 20: Example Compressed Packet with RH3.		Figure 20: Example Compressed Packet with SRH.
	One may note that the RPI is provided. This is because the address		One may note that the RPI is provided. This is because the address
	of the root that is the source of the IP-in-IP header is elided and		of the root that is the source of the IP-in-IP header is elided and
	inferred from the InstanceID in the RPI. Once found from a local		inferred from the RPLInstanceID in the RPI. Once found from a local
	context, that address is used as Compression Reference to expand		context, that address is used as Compression Reference to expand
	addresses in the RH3-6LoRH.		addresses in the SRH-6LoRH.
	With the RPL specifications available at the time of writing this		With the RPL specifications available at the time of writing this
	draft, the root is the only node that may incorporate a RH3 in an IP		draft, the root is the only node that may incorporate a SRH in an IP
	packet. When the root forwards a packet that it did not generate, it		packet. When the root forwards a packet that it did not generate, it
	has to encapsulate the packet with IP-in-IP.		has to encapsulate the packet with IP-in-IP.
	But if the root generates the packet towards a node in its DODAG,		But if the root generates the packet towards a node in its DODAG,
	then it should avoid the extra IP-in-IP as illustrated in Figure 21:		then it should avoid the extra IP-in-IP as illustrated in Figure 21:
	+- ... -+-+-+ ... +-+-+-+ ... -+-+-+-+-+-+-+-++-+- ... -+-+-+-+-+...		+- ... -+-+-+ ... +-+-+-+ ... -+-+-+-+-+-+-+-++-+- ... -+-+-+-+-+...
	|11110001| RH3-6LoRH | NH=1 | 11110CPP | Compressed | UDP		|11110001| SRH-6LoRH | NH=1 | 11110CPP | Compressed | UDP
	|Page 1 | Type1 S=3 | LOWPAN-IPHC| LOWPAN-NHC| UDP header | Payload		|Page 1 | Type1 S=3 | LOWPAN-IPHC| LOWPAN-NHC| UDP header | Payload
	+- ... -+-+-+ ... +-+-+-+ ... -+-+-+-+-+-+-+-++-+- ... -+-+-+-+-+...		+- ... -+-+-+ ... +-+-+-+ ... -+-+-+-+-+-+-+-++-+- ... -+-+-+-+-+...
	<- RFC 6282 ->		<- RFC 6282 ->
	Figure 21: compressed RH3 4*2bytes entries sourced by root.		Figure 21: compressed SRH 4*2bytes entries sourced by root.
	Note: the RPI is not represented though RPL [RFC6550] generally		Note: the RPI is not represented though RPL [RFC6550] generally
	expects it. In this particular case, since the Compression Reference		expects it. In this particular case, since the Compression Reference
	for the RH3-6LoRH is the source address in the LOWPAN-IPHC, and the		for the SRH-6LoRH is the source address in the LOWPAN-IPHC, and the
	routing is strict along the source route path, the RPI does not		routing is strict along the source route path, the RPI does not
	appear to be absolutely necessary.		appear to be absolutely necessary.
	In Figure 21, all the nodes along the source route path share a same		In Figure 21, all the nodes along the source route path share a same
	/112 prefix. This is typical of IPv6 addresses derived from an		/112 prefix. This is typical of IPv6 addresses derived from an
	IEEE802.15.4 short address, as long as all the nodes share a same		IEEE802.15.4 short address, as long as all the nodes share a same
	PAN-ID. In that case, a type-1 RH3-6LoRH header can be used for		PAN-ID. In that case, a type-1 SRH-6LoRH header can be used for
	encoding. The IPv6 address of the root is taken as reference, and		encoding. The IPv6 address of the root is taken as reference, and
	only the last 2 octets of the address of the intermediate hops is		only the last 2 octets of the address of the intermediate hops is
	encoded. The Size of 3 indicates 4 hops, resulting in a RH3-6LoRH of		encoded. The Size of 3 indicates 4 hops, resulting in a SRH-6LoRH of
	10 bytes.		10 bytes.
	A.3. Example of RH3-6LoRH life-cycle		A.3. Example of SRH-6LoRH life-cycle
	This section illustrates the operation specified in Section 5.5 of		This section illustrates the operation specified in Section 5.6 of
	forwarding a packet with a compressed RH3 along an A->B->C->D source		forwarding a packet with a compressed SRH along an A->B->C->D source
	route path. The operation of popping addresses is exemplified at		route path. The operation of popping addresses is exemplified at
	each hop.		each hop.
	Packet as received by node A		Packet as received by node A
	----------------------------		----------------------------
	Type 3 RH3-6LoRH Size = 0 AAAA AAAA AAAA AAAA		Type 3 SRH-6LoRH Size = 0 AAAA AAAA AAAA AAAA
	Type 1 RH3-6LoRH Size = 0 BBBB		Type 1 SRH-6LoRH Size = 0 BBBB
	Type 2 RH3-6LoRH Size = 1 CCCC CCCC		Type 2 SRH-6LoRH Size = 1 CCCC CCCC
	DDDD DDDD		DDDD DDDD
	Step 1 popping BBBB the first entry of the next RH3-6LoRH		Step 1 popping BBBB the first entry of the next SRH-6LoRH
	Step 2 next is if larger value (2 vs. 1) the RH3-6LoRH is removed		Step 2 next is if larger value (2 vs. 1) the SRH-6LoRH is removed
	Type 3 RH3-6LoRH Size = 0 AAAA AAAA AAAA AAAA		Type 3 SRH-6LoRH Size = 0 AAAA AAAA AAAA AAAA
	Type 2 RH3-6LoRH Size = 1 CCCC CCCC		Type 2 SRH-6LoRH Size = 1 CCCC CCCC
	DDDD DDDD		DDDD DDDD
	Step 3: recursion ended, coalescing BBBB with the first entry		Step 3: recursion ended, coalescing BBBB with the first entry
	Type 3 RH3-6LoRH Size = 0 AAAA AAAA AAAA BBBB		Type 3 SRH-6LoRH Size = 0 AAAA AAAA AAAA BBBB
	Step 4: routing based on next segment endpoint to B		Step 4: routing based on next segment endpoint to B
	Figure 22: Processing at Node A.		Figure 22: Processing at Node A.
	Packet as received by node B		Packet as received by node B
	----------------------------		----------------------------
	Type 3 RH3-6LoRH Size = 0 AAAA AAAA AAAA BBBB		Type 3 SRH-6LoRH Size = 0 AAAA AAAA AAAA BBBB
	Type 2 RH3-6LoRH Size = 1 CCCC CCCC		Type 2 SRH-6LoRH Size = 1 CCCC CCCC
	DDDD DDDD		DDDD DDDD
	Step 1 popping CCCC CCCC, the first entry of the next RH3-6LoRH		Step 1 popping CCCC CCCC, the first entry of the next SRH-6LoRH
	Step 2 removing the first entry and decrementing the Size (by 1)		Step 2 removing the first entry and decrementing the Size (by 1)
	Type 3 RH3-6LoRH Size = 0 AAAA AAAA AAAA BBBB		Type 3 SRH-6LoRH Size = 0 AAAA AAAA AAAA BBBB
	Type 2 RH3-6LoRH Size = 0 DDDD DDDD		Type 2 SRH-6LoRH Size = 0 DDDD DDDD
	Step 3: recursion ended, coalescing CCCC CCCC with the first entry		Step 3: recursion ended, coalescing CCCC CCCC with the first entry
	Type 3 RH3-6LoRH Size = 0 AAAA AAAA CCCC CCCC		Type 3 SRH-6LoRH Size = 0 AAAA AAAA CCCC CCCC
	Step 4: routing based on next segment endpoint to C		Step 4: routing based on next segment endpoint to C
	Figure 23: Processing at Node B.		Figure 23: Processing at Node B.
	Packet as received by node C		Packet as received by node C
	----------------------------		----------------------------
	Type 3 RH3-6LoRH Size = 0 AAAA AAAA CCCC CCCC		Type 3 SRH-6LoRH Size = 0 AAAA AAAA CCCC CCCC
	Type 2 RH3-6LoRH Size = 0 DDDD DDDD		Type 2 SRH-6LoRH Size = 0 DDDD DDDD
	Step 1 popping DDDD DDDD, the first entry of the next RH3-6LoRH		Step 1 popping DDDD DDDD, the first entry of the next SRH-6LoRH
	Step 2 the RH3-6LoRH is removed		Step 2 the SRH-6LoRH is removed
	Type 3 RH3-6LoRH Size = 0 AAAA AAAA CCCC CCCC		Type 3 SRH-6LoRH Size = 0 AAAA AAAA CCCC CCCC
	Step 3: recursion ended, coalescing DDDD DDDDD with the first entry		Step 3: recursion ended, coalescing DDDD DDDDD with the first entry
	Type 3 RH3-6LoRH Size = 0 AAAA AAAA DDDD DDDD		Type 3 SRH-6LoRH Size = 0 AAAA AAAA DDDD DDDD
	Step 4: routing based on next segment endpoint to D		Step 4: routing based on next segment endpoint to D
	Figure 24: Processing at Node C.		Figure 24: Processing at Node C.
	Packet as received by node D		Packet as received by node D
	----------------------------		----------------------------
	Type 3 RH3-6LoRH Size = 0 AAAA AAAA DDDD DDDD		Type 3 SRH-6LoRH Size = 0 AAAA AAAA DDDD DDDD
	Step 1 the RH3-6LoRH is removed.		Step 1 the SRH-6LoRH is removed.
	Step 2 no more header, routing based on inner IP header.		Step 2 no more header, routing based on inner IP header.
	Figure 25: Processing at Node D.		Figure 25: Processing at Node D.
	Authors' Addresses		Authors' Addresses
	Pascal Thubert (editor)		Pascal Thubert (editor)
	Cisco Systems		Cisco Systems
	Building D - Regus		Building D - Regus
	45 Allee des Ormes		45 Allee des Ormes
End of changes. 116 change blocks.
	218 lines changed or deleted		282 lines changed or added
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