draft-ietf-roll-turnon-rfc8138-09.txt		draft-ietf-roll-turnon-rfc8138-10.txt
	ROLL P. Thubert, Ed.		ROLL P. Thubert, Ed.
	Internet-Draft L. Zhao		Internet-Draft L. Zhao
	Updates: 8138 (if approved) Cisco Systems		Updates: 8138 (if approved) Cisco Systems
	Intended status: Standards Track 27 July 2020		Intended status: Standards Track 5 August 2020
	Expires: 28 January 2021		Expires: 6 February 2021
	A RPL DODAG Configuration Option for the 6LoWPAN Routing Header		A RPL DODAG Configuration Option for the 6LoWPAN Routing Header
	draft-ietf-roll-turnon-rfc8138-09		draft-ietf-roll-turnon-rfc8138-10
	Abstract		Abstract
	This document updates RFC 8138 by defining a bit in the RPL DODAG		This document updates RFC 8138 by defining a bit in the RPL DODAG
	Configuration Option to indicate whether compression is used within		Configuration Option to indicate whether compression is used within
	the RPL Instance, and specify the behavior of RFC 8138-capable nodes		the RPL Instance, and specify the behavior of RFC 8138-capable nodes
	when the bit is set and reset.		when the bit is set and reset.
	Status of This Memo		Status of This Memo
	skipping to change at page 1, line 34 ¶		skipping to change at page 1, line 34 ¶
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at https://datatracker.ietf.org/drafts/current/.		Drafts is at https://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	This Internet-Draft will expire on 28 January 2021.		This Internet-Draft will expire on 6 February 2021.
	Copyright Notice		Copyright Notice
	Copyright (c) 2020 IETF Trust and the persons identified as the		Copyright (c) 2020 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents (https://trustee.ietf.org/		Provisions Relating to IETF Documents (https://trustee.ietf.org/
	license-info) in effect on the date of publication of this document.		license-info) in effect on the date of publication of this document.
	Please review these documents carefully, as they describe your rights		Please review these documents carefully, as they describe your rights
	skipping to change at page 2, line 20 ¶		skipping to change at page 2, line 20 ¶
	2.2. Glossary . . . . . . . . . . . . . . . . . . . . . . . . 3		2.2. Glossary . . . . . . . . . . . . . . . . . . . . . . . . 3
	2.3. Requirements Language . . . . . . . . . . . . . . . . . . 4		2.3. Requirements Language . . . . . . . . . . . . . . . . . . 4
	3. The RPL DODAG Configuration Option . . . . . . . . . . . . . 4		3. The RPL DODAG Configuration Option . . . . . . . . . . . . . 4
	4. Updating RFC 8138 . . . . . . . . . . . . . . . . . . . . . . 5		4. Updating RFC 8138 . . . . . . . . . . . . . . . . . . . . . . 5
	5. Transition Scenarios . . . . . . . . . . . . . . . . . . . . 5		5. Transition Scenarios . . . . . . . . . . . . . . . . . . . . 5
	5.1. Coexistence . . . . . . . . . . . . . . . . . . . . . . . 6		5.1. Coexistence . . . . . . . . . . . . . . . . . . . . . . . 6
	5.2. Inconsistent State While Migrating . . . . . . . . . . . 6		5.2. Inconsistent State While Migrating . . . . . . . . . . . 6
	5.3. Rolling Back . . . . . . . . . . . . . . . . . . . . . . 6		5.3. Rolling Back . . . . . . . . . . . . . . . . . . . . . . 6
	6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7		6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
	7. Security Considerations . . . . . . . . . . . . . . . . . . . 7		7. Security Considerations . . . . . . . . . . . . . . . . . . . 7
	8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 7		8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8
	9. Normative References . . . . . . . . . . . . . . . . . . . . 7		9. Normative References . . . . . . . . . . . . . . . . . . . . 8
	10. Informative References . . . . . . . . . . . . . . . . . . . 8		10. Informative References . . . . . . . . . . . . . . . . . . . 9
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
	1. Introduction		1. Introduction
	The packet compression technique defined in [RFC8138] can only be		The packet compression technique defined in [RFC8138] can only be
	activated in a RPL [RFC6550] network when all the nodes support it.		activated in a RPL [RFC6550] network when all the nodes support it.
	Otherwise, a non-capable node acting as leaf-only would fail to		Otherwise, a non-capable node acting as leaf-only would fail to
	communicate, and acting as a router it would drop the compressed		communicate, and acting as a router it would drop the compressed
	packets and black-hole a portion of the network.		packets and black-hole a portion of the network.
	skipping to change at page 3, line 9 ¶		skipping to change at page 3, line 9 ¶
	The idea is to use the flag to maintain the compression inactive		The idea is to use the flag to maintain the compression inactive
	during the migration phase. When the migration is complete (e.g., as		during the migration phase. When the migration is complete (e.g., as
	known by network management and/or inventory), the flag is set and		known by network management and/or inventory), the flag is set and
	the compression is globally activated in the whole DODAG.		the compression is globally activated in the whole DODAG.
	2. Terminology		2. Terminology
	2.1. References		2.1. References
	The Terminology used in this document is consistent with and		The terminology used in this document is consistent with and
	incorporates that described in "Terms Used in Routing for Low-Power		incorporates that described in "Terms Used in Routing for Low-Power
	and Lossy Networks (LLNs)" [RFC7102]. Other terms in use in LLNs are		and Lossy Networks (LLNs)" [RFC7102]. Other terms in use in LLNs are
	found in "Terminology for Constrained-Node Networks" [RFC7228].		found in "Terminology for Constrained-Node Networks" [RFC7228].
	"RPL", the "RPL Packet Information" (RPI), "RPL Instance" (indexed by		"RPL", the "RPL Packet Information" (RPI), and "RPL Instance"
	a RPLInstanceID) are defined in "RPL: IPv6 Routing Protocol for		(indexed by a RPLInstanceID) are defined in "RPL: IPv6 Routing
	Low-Power and Lossy Networks" [RFC6550]. The RPI is the abstract		Protocol for Low-Power and Lossy Networks" [RFC6550]. The RPI is the
	information that RPL defines to be placed in data packets, e.g., as		abstract information that RPL defines to be placed in data packets,
	the RPL Option [RFC6553] within the IPv6 Hop-By-Hop Header. By		e.g., as the RPL Option [RFC6553] within the IPv6 Hop-By-Hop Header.
	extension the term "RPI" is often used to refer to the RPL Option		By extension the term "RPI" is often used to refer to the RPL Option
	itself. The DODAG Information Solicitation (DIS), Destination		itself. The DODAG Information Solicitation (DIS), Destination
	Advertisement Object (DAO) and DODAG Information Object (DIO)		Advertisement Object (DAO) and DODAG Information Object (DIO)
	messages are also specified in [RFC6550].		messages are also specified in [RFC6550].
	This document uses the terms RPL-Unaware Leaf (RUL) and RPL Aware		This document uses the terms RPL-Unaware Leaf (RUL) and RPL-Aware
	Leaf (RAL) consistently with "Using RPI Option Type, Routing Header		Leaf (RAL) consistently with "Using RPI Option Type, Routing Header
	for Source Routes and IPv6-in-IPv6 encapsulation in the RPL Data		for Source Routes and IPv6-in-IPv6 encapsulation in the RPL Data
	Plane" [USEofRPLinfo]. The term RPL-Aware Node (RAN) refers to a		Plane" [USEofRPLinfo]. The term RPL-Aware Node (RAN) refers to a
	node that is either a RAL or a RPL Router. A RAN manages the		node that is either a RAL or a RPL Router. A RAN manages the
	reachability of its addresses and prefixes by injecting them in RPL		reachability of its addresses and prefixes by injecting them in RPL
	by itself. In contrast, a RUL leverages "Registration Extensions for		by itself. In contrast, a RUL leverages "Registration Extensions for
	IPv6 over Low-Power Wireless Personal Area Network (6LoWPAN) Neighbor		IPv6 over Low-Power Wireless Personal Area Network (6LoWPAN) Neighbor
	Discovery" [RFC8505] to obtain reachability services from its parent		Discovery" [RFC8505] to obtain reachability services from its parent
	router(s) as specified in "Routing for RPL Leaves" [UNAWARE-LEAVES].		router(s) as specified in "Routing for RPL Leaves" [UNAWARE-LEAVES].
	skipping to change at page 4, line 49 ¶		skipping to change at page 4, line 49 ¶
	The suggested bit position of the "T" flag is indicated in Section 6.		The suggested bit position of the "T" flag is indicated in Section 6.
	[RFC6550] states, when referring to the DODAG Configuration Option,		[RFC6550] states, when referring to the DODAG Configuration Option,
	that "Nodes other than the DODAG Root MUST NOT modify this		that "Nodes other than the DODAG Root MUST NOT modify this
	information when propagating the DODAG Configuration option".		information when propagating the DODAG Configuration option".
	Therefore, a legacy parent propagates the "T" flag as set by the Root		Therefore, a legacy parent propagates the "T" flag as set by the Root
	whether it supports this specification or not. So when the "T" flag		whether it supports this specification or not. So when the "T" flag
	is set, it is transparently flooded to all the nodes in the DODAG.		is set, it is transparently flooded to all the nodes in the DODAG.
	Section 6.3.1 of [RFC6550] defines a 3-bit Mode of Operation (MOP) in		Section 6.3.1 of [RFC6550] defines a 3-bit Mode of Operation (MOP) in
	the DIO Base Object. For MOP values 0 to 6, the use of compression		the DIO Base Object. This specification applies to MOP values 0 to
	depends on the "T" flag as specified in this document. A MOP value		6. For a MOP value of 7, the compression MUST be used by default
	of 7 and above MUST use compression by default and ignore the setting		regardless of the setting of the "T" flag.
	of the "T" flag.
	4. Updating RFC 8138		4. Updating RFC 8138
	A node SHOULD source packets in the compressed form using [RFC8138]		A node SHOULD source packets in the compressed form using [RFC8138]
	if and only if the "T" flag is set. This behaviour can be overridden		if and only if the "T" flag is set. This behaviour can be overridden
	by e.g., configuration or network management. Overriding may be		by e.g., configuration or network management. Overriding may be
	needed e.g., to cope with a legacy implementations of the Root that		needed e.g., to cope with a legacy implementation of the Root that
	supports [RFC8138] but not this specification and cannot set the "T"		supports [RFC8138] but not this specification and cannot set the "T"
	flag.		flag.
	The decision of using [RFC8138] is made by the originator of the		The decision of using [RFC8138] is made by the originator of the
	packet depending on its capabilities and its knowledge of the state		packet depending on its capabilities and its knowledge of the state
	of the "T" flag. A router that encapsulates a packet is the		of the "T" flag. A router that encapsulates a packet is the
	originator of the resulting packet and is responsible to compress the		originator of the resulting packet and is responsible to compress the
	outer headers with [RFC8138], but it MUST leave the encapsulated		outer headers with [RFC8138], but it MUST leave the encapsulated
	packet as is.		packet as is.
	An external target [USEofRPLinfo] is not expected to support		An external target [USEofRPLinfo] is not expected to support
	[RFC8138]. In most cases, packets from/to an external target are		[RFC8138]. In most cases, packets from and to an external target are
	tunneled back and forth between the RPL border router and the Root		tunneled back and forth between the border router (referred to as
	regardless of the MOP used in the RPL DODAG. The inner packet is		6LR) that serves the external target and the Root, regardless of the
	typically not compressed with [RFC8138] so the 6LR just needs to		MOP used in the RPL DODAG. The inner packet is typically not
	decapsulate the (compressed) outer header and forward the		compressed with [RFC8138], so for outgoing packets, the border router
	(uncompressed) inner packet towards the external target.		just needs to decapsulate the (compressed) outer header and forward
			the (uncompressed) inner packet towards the external target.
	A router MUST uncompress a packet that is to be forwarded to an		A router MUST uncompress a packet that is to be forwarded to an
	external target. Otherwise, the router MUST forward the packet in		external target. Otherwise, the router MUST forward the packet in
	the form that the source used, either compressed or uncompressed.		the form that the source used, either compressed or uncompressed.
	A RUL [UNAWARE-LEAVES] is both a leaf and an external target . A RUL		A RUL [UNAWARE-LEAVES] is both a leaf and an external target. A RUL
	does not participate in RPL and depends on the parent router to		does not participate in RPL and depends on the parent router to
	obtain connectivity. In the case of a RUL, forwarding towards an		obtain connectivity. In the case of a RUL, forwarding towards an
	external target actually means delivering the packet.		external target actually means delivering the packet.
	5. Transition Scenarios		5. Transition Scenarios
	A node that supports [RFC8138] but not this specification can only be		A node that supports [RFC8138] but not this specification can only be
	used in an homogeneous network. Enabling the [RFC8138] compression		used in an homogeneous network. Enabling the [RFC8138] compression
	requires a "flag day"; all nodes must be upgraded, and then the		without a turn-on signaling requires a "flag day"; all nodes must be
	network can be rebooted with the [RFC8138] compression turned on.		upgraded, and then the network can be rebooted with the [RFC8138]
			compression turned on.
	The intent for this specification is to perform a migration once and		The intent for this specification is to perform a migration once and
	for all without the need for a flag day. In particular it is not the		for all without the need for a flag day. In particular it is not the
	intention to undo the setting of the "T" flag. Though it is possible		intention to undo the setting of the "T" flag. Though it is possible
	to roll back (see Section 5.3), adding nodes that do not support		to roll back (see Section 5.3), adding nodes that do not support
	[RFC8138] after a roll back may be problematic if the roll back did		[RFC8138] after a roll back may be problematic if the roll back did
	not fully complete.		not fully complete.
	5.1. Coexistence		5.1. Coexistence
	skipping to change at page 7, line 44 ¶		skipping to change at page 7, line 44 ¶
	Setting and resetting the "T" flag may create inconsistencies in the		Setting and resetting the "T" flag may create inconsistencies in the
	network but as long as all nodes are upgraded to [RFC8138] support		network but as long as all nodes are upgraded to [RFC8138] support
	they will be able to forward both forms. The source is responsible		they will be able to forward both forms. The source is responsible
	for selecting whether the packet is compressed or not, and all		for selecting whether the packet is compressed or not, and all
	routers must use the format that the source selected. So the result		routers must use the format that the source selected. So the result
	of an inconsistency is merely that both forms will be present in the		of an inconsistency is merely that both forms will be present in the
	network, at an additional cost of bandwidth for packets in the		network, at an additional cost of bandwidth for packets in the
	uncompressed form.		uncompressed form.
			An attacker in the middle of the network may reset the "T" flag to
			cause extra energy spending in its subDAG. Conversely it may set the
			"T" flag, so that nodes located downstream would compress when that
			it is not desired, potentially resulting in the loss of packets. In
			a tree structure, the attacker would be in position to drop the
			packets from and to the attacked nodes. So the attacks above would
			be more complex and more visible than simply dropping selected
			packets. The downstream node may have other parents and see both
			settings, which could raise attention.
	8. Acknowledgments		8. Acknowledgments
	The authors wish to thank Alvaro Retana, Dominique Barthel and Rahul		The authors wish to thank Carles Gomez, Alvaro Retana, Dominique
	Jadhav for their in-depth reviews and constructive suggestions.		Barthel and Rahul Jadhav for their in-depth reviews and constructive
			suggestions.
	Also many thanks to Michael Richardson for being always helpful and		Also many thanks to Michael Richardson for being always helpful and
	responsive when need comes.		responsive when need comes.
	9. Normative References		9. 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,
	<https://www.rfc-editor.org/info/rfc2119>.		<https://www.rfc-editor.org/info/rfc2119>.
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