< draft-ietf-roll-mopex-01.txt		draft-ietf-roll-mopex-02.txt >
	ROLL R. Jadhav, Ed.		ROLL R. Jadhav, Ed.
	Internet-Draft Huawei Tech		Internet-Draft Huawei Tech
	Intended status: Standards Track P. Thubert		Intended status: Standards Track P. Thubert
	Expires: December 7, 2020 Cisco		Expires: April 2, 2021 Cisco
	M. Richardson		M. Richardson
	Sandelman Software Works		Sandelman Software Works
	June 5, 2020		September 29, 2020
	Mode of Operation extension		Mode of Operation extension
	draft-ietf-roll-mopex-01		draft-ietf-roll-mopex-02
	Abstract		Abstract
	RPL allows different mode of operations which allows nodes to have a		RPL allows different mode of operations which allows nodes to have a
	consensus on the basic primitives that must be supported to join the		consensus on the basic primitives that must be supported to join the
	network. The MOP field in [RFC6550] is of 3 bits and is fast		network. The MOP field in [RFC6550] is of 3 bits and is fast
	depleting. This document extends the MOP for future use.		depleting. This document extends the MOP for future use.
	Status of This Memo		Status of This Memo
	skipping to change at page 1, line 36 ¶		skipping to change at page 1, line 36 ¶
	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 December 7, 2020.		This Internet-Draft will expire on April 2, 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		Provisions Relating to IETF Documents
	(https://trustee.ietf.org/license-info) in effect on the date of		(https://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	skipping to change at page 2, line 22 ¶		skipping to change at page 2, line 22 ¶
	3. Extended MOP Control Message Option . . . . . . . . . . . . . 4		3. Extended MOP Control Message Option . . . . . . . . . . . . . 4
	3.1. Handling MOPex . . . . . . . . . . . . . . . . . . . . . 4		3.1. Handling MOPex . . . . . . . . . . . . . . . . . . . . . 4
	3.2. Use of values 0-6 in the MOPex option . . . . . . . . . . 4		3.2. Use of values 0-6 in the MOPex option . . . . . . . . . . 4
	4. Extending RPL Control Options . . . . . . . . . . . . . . . . 4		4. Extending RPL Control Options . . . . . . . . . . . . . . . . 4
	5. Implementation Considerations . . . . . . . . . . . . . . . . 6		5. Implementation Considerations . . . . . . . . . . . . . . . . 6
	6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6		6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
	7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6		7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
	7.1. Mode of operation: MOPex . . . . . . . . . . . . . . . . 6		7.1. Mode of operation: MOPex . . . . . . . . . . . . . . . . 6
	7.2. New options: MOPex and Capabilities . . . . . . . . . . . 6		7.2. New options: MOPex and Capabilities . . . . . . . . . . . 6
	7.3. New Registry for Extended-MOP-value . . . . . . . . . . . 7		7.3. New Registry for Extended-MOP-value . . . . . . . . . . . 7
			7.4. Change in RPL Control Option field . . . . . . . . . . . 7
	8. Security Considerations . . . . . . . . . . . . . . . . . . . 7		8. Security Considerations . . . . . . . . . . . . . . . . . . . 7
	9. References . . . . . . . . . . . . . . . . . . . . . . . . . 7		9. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
	9.1. Normative References . . . . . . . . . . . . . . . . . . 7		9.1. Normative References . . . . . . . . . . . . . . . . . . 8
	9.2. Informative References . . . . . . . . . . . . . . . . . 8		9.2. Informative References . . . . . . . . . . . . . . . . . 8
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
	1. Introduction		1. Introduction
	RPL [RFC6550] specifies a proactive distance-vector based routing		RPL [RFC6550] specifies a proactive distance-vector based routing
	scheme. The protocol creates a DAG-like structure which operates		scheme. The protocol creates a DAG-like structure which operates
	with a given "Mode of Operation" (MOP) determining the minimal and		with a given "Mode of Operation" (MOP) determining the minimal and
	mandatory set of primitives to be supported by all the participating		mandatory set of primitives to be supported by all the participating
	nodes.		nodes.
	MOP as per [RFC6550] is a 3-bit value carried in DIO messages and is		MOP as per [RFC6550] is a 3-bit value carried in DIO messages and is
	specific to the RPL Instance. The receipient of the DIO message can		specific to the RPL Instance. The recipient of the DIO message can
	join the specified network as a router only when it can support the		join the specified network as a router only when it can support the
	primitives as required by the mode of operation value. For example,		primitives as required by the mode of operation value. For example,
	in case of MOP=3 (Storing MOP with multicast support) the nodes can		in case of MOP=3 (Storing MOP with multicast support) the nodes can
	join the network as routers only when they can handle the DAO		join the network as routers only when they can handle the DAO
	advertisements from the peers and manage routing tables. The 3-bit		advertisements from the peers and manage routing tables. The 3-bit
	value is already exhausted and requires replenishment. This document		value is already exhausted and requires replenishment. This document
	introduces a mechanism to extend mode of operation values.		introduces a mechanism to extend mode of operation values.
	This document further extends the RPL Control Option syntax to handle		This document further extends the RPL Control Option syntax to handle
	generic flags. The primary aim of these flags is to define the		generic flags. The primary aim of these flags is to define the
	behaviour of a node not supporting the given control type. If a node		behaviour of a node not supporting the given control type. If a node
	does not support a given RPL Control Option, there are three		does not support a given RPL Control Option, there are following
	possibilities:		possibilities:
	REQ1: Strip off the option		Strip off the option
	REQ2: Copy the option as-is		Copy the option as-is
	REQ3: Ignore the message containing this option		Ignore the message containing this option
	REQ4: Let the node join in only as a 6LN to this parent		Let the node join in only as a 6LN to this parent
	1.1. Requirements Language and Terminology		1.1. Requirements Language and Terminology
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this		"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
	document are to be interpreted as described in RFC 2119 [RFC2119].		document are to be interpreted as described in RFC 2119 [RFC2119].
	MOP: Mode of Operation. Identifies the mode of operation of the RPL		MOP: Mode of Operation. Identifies the mode of operation of the RPL
	Instance as administratively provisioned at and distributed by the		Instance as administratively provisioned at and distributed by the
	DODAG root.		DODAG root.
	MOPex: Extended MOP: This document extends the MOP values over a		MOPex: Extended MOP: This document extends the MOP values over a
	bigger range. This extension of MOP is called MOPex.		bigger range. This extension of MOP is called MOPex.
	DAO: DODAG Advertisement Object. An RPL message used to advertise		DAO: DODAG Advertisement Object. An RPL message used to advertise
	the target information in order to establish routing adjacencies.		the target information in order to establish routing adjacencies.
	DIO: DODAG Information Object. An RPL message initiated by the root		DIO: DODAG Information Object. An RPL message initiated by the root
	and is used to advertise the network configuration information.		and used to advertise the network configuration information.
	Current parent: Parent 6LR node before switching to the new path.		Current parent: Parent 6LR node before switching to the new path.
	This document uses terminology described in [RFC6550]. For the sake		This document uses terminology described in [RFC6550]. For the sake
	of readability all the known relevant terms are repeated in this		of readability all the known relevant terms are repeated in this
	section.		section.
	2. Requirements for this document		2. Requirements for this document
	Following are the requirements considered for this documents:		Following are the requirements considered for this documents:
	REQ1: MOP extension. Current MOP of 3-bit is fast depleting. An		REQ1: MOP extension. Current MOP of 3-bit is fast depleting. An
	MOP extension needs to extend the possibility of adding new		MOP extension needs to extend the possibility of adding new
	MOPs in the future.		MOPs in the future.
	REQ2: Backwards compatibility. The new options and new fields in		REQ2: Backwards compatibility. The new options and new fields in
	the DIO message should be backward compatible i.e. if there		the DIO message should be backward compatible i.e. if there
	are nodes which support old MOPs they could still operate in		are nodes which support old MOPs they could still operate in
	their own instances.		their own RPL Instances.
	3. Extended MOP Control Message Option		3. Extended MOP Control Message Option
	This document reserves existing MOP value 7 to be used as an		This document reserves existing MOP value 7 to be used as an
	extender. DIO messages with MOP value of 7 may refer to the Extended		extender. DIO messages with MOP value of 7 may refer to the Extended
	MOP (MOPex) option in the DIO message.		MOP (MOPex) option in the DIO message.
	0 1 2		0 1 2
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+---------------		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+---------------
	skipping to change at page 4, line 32 ¶		skipping to change at page 4, line 32 ¶
	3.1. Handling MOPex		3.1. Handling MOPex
	The MOPex option MUST be used only if the base DIO MOP is 7. If the		The MOPex option MUST be used only if the base DIO MOP is 7. If the
	base DIO MOP is 7 and if the MOPex option is not present then the DIO		base DIO MOP is 7 and if the MOPex option is not present then the DIO
	MUST be silently ignored. If the base DIO MOP is less than 7 then		MUST be silently ignored. If the base DIO MOP is less than 7 then
	MOPex MUST NOT be used. In case the base MOP is 7 and if the MOPex		MOPex MUST NOT be used. In case the base MOP is 7 and if the MOPex
	option is present, then the implementation MUST use the final MOP		option is present, then the implementation MUST use the final MOP
	value from the MOPex.		value from the MOPex.
	Note that [RFC6550] allows the node who does not support the received		Note that [RFC6550] allows a node that does not support the received
	MOP to still join the network as a leaf node. This semantic		MOP to still join the network as a leaf node. This semantics
	continues to be true even in case of MOPex.		continues to be true even in case of MOPex.
	3.2. Use of values 0-6 in the MOPex option		3.2. Use of values 0-6 in the MOPex option
	The MOPex option could also be allowed to re-use the values 0-6,		The MOPex option could also be allowed to re-use the values 0-6,
	which have been used for MOP so far. The use of current MOPs in		which have been used for MOP so far. The use of current MOPs in
	MOPex indicates that the MOP is supported with extended set of		MOPex indicates that the MOP is supported with extended set of
	semantics for e.g., the capability options		semantics for e.g., the capability options
	[I-D.ietf-roll-capabilities].		[I-D.ietf-roll-capabilities].
	4. Extending RPL Control Options		4. Extending RPL Control Options
	Section 6.7.1 of RFC6550 explains the RPL Control Message Option		Section 6.7.1 of RFC6550 explains the RPL Control Message Option
	Generic Format. This document extends this format to following:		Generic Format. This document extends this format to following:
	0 1 2		0 1 2
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-----------		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-----------
	| |X| OptionType| Option Length |Opt Flags|J|I|C| Option Data		|X| OptionType| Option Length |Opt Flags|J|I|C| Option Data
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-----------		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-----------
	Figure 2: Extended RPL Option Format		Figure 2: Extended RPL Option Format
	New fields in extended RPL Control Message Option Format:		New fields in extended RPL Control Message Option Format:
	'X' bit in Option Type: Value 1 indicates that this is an extended		'X' bit in Option Type: Value 1 indicates that this is an extended
	option. If the 'X' flag is set, a 1 byte Option Flags follows the		option. If the 'X' flag is set, a 1 byte Option Flags follows the
	Option Length field.		Option Length field.
	Option Length: 8-bit unsigned integer, representing the length in		Option Length: 8-bit unsigned integer, representing the length in
	octets of the option, not including the Option Type and Length		octets of the option, not including the Option Type and Length
	fields. Option Flags and variable length Option Data fields are		fields. Option Flags and variable length Option Data fields are
	included in the length.		included in the length.
	'J' (Join) bit in Option Flags: A node MUST join only as a 6LN if		'J' (Join) bit in Option Flags: A node MUST join only as a 6LN if
	the Option Type is not understood.		the Option Type is not understood.
	'C' (Copy) bit in Option Flags: A node which does not understand		'C' (Copy) bit in Option Flags: A node that does not understand
	the Option Type MUST copy the Option while generating the		the Option Type MUST copy the Option while generating the
	corresponding message. For e.g., if a 6LR receives a DIO message		corresponding message. For e.g., if a 6LR receives a DIO message
	with an unknown Option with 'C' bit set and if the 6LR choses to		with an unknown Option with 'C' bit set and if the 6LR choses to
	accept this node as the preferred parent then the node MUST copy		accept this node as the preferred parent then the node MUST copy
	this option in the subsequent DIO message it generates.		this option in the subsequent DIO message it generates.
	Alternatively, if the 'C' flag is unset the node MUST strip off		Alternatively, if the 'C' flag is unset the node MUST strip off
	the option and process the message.		the option and process the message.
	'I' (Ignore) bit in Option Flags: A node which does not understand		'I' (Ignore) bit in Option Flags: A node that does not understand
	the Option Type MUST ignore this whole message if the 'I' bit is		the Option Type MUST ignore this whole message if the 'I' bit is
	set. If 'I' bit is set than the value of 'J' and 'C' bits are		set. If 'I' bit is set than the value of 'J' and 'C' bits are
	irrelevant and the message MUST be ignored.		irrelevant and the message MUST be ignored.
	Note that this format does not deprecate the previous format, it		Note that this format does not deprecate the previous format, it
	simply extends it and the new format is applicable only when 2nd bit		simply extends it and the new format is applicable only when 2nd bit
	('X' flag) of the Option Type is set. Option Type 0x40 to 0x7F are		('X' flag) of the Option Type is set. Option Type 0x80 to 0xFF are
	thus applicable only as extended options.		thus applicable only as extended options.
	+---------+---------+-----------------------------------------------+		+---------+---------+-----------------------------------------------+
	| 'J' bit | 'C' bit | Handling |		| 'J' bit | 'C' bit | Handling |
	+---------+---------+-----------------------------------------------+		+---------+---------+-----------------------------------------------+
	| 0 | 0 | Strip off the option, and the node can join |		| 0 | 0 | Strip off the option, and the node can join |
	| | | as 6LR |		| | | as 6LR |
	| 0 | 1 | Copy the option, and the node can join as 6LR |		| 0 | 1 | Copy the option, and the node can join as 6LR |
	| 1 | NA | Join as 6LN |		| 1 | NA | Join as 6LN |
	+---------+---------+-----------------------------------------------+		+---------+---------+-----------------------------------------------+
	Table 1: Option Flags handling		Table 1: Option Flags handling
	If a node receives an unknown Option without 'X' flag set then the		If a node receives an unknown Option without 'X' flag set then the
	node MUST ignore the option and process the message. The option MUST		node MUST ignore the option and process the message. The option MUST
	be treated as if J=0, C=0, I=0.		be treated as if J=0, C=0, I=0.
	5. Implementation Considerations		5. Implementation Considerations
	[RFC6550], it was possible to discard an unsupported DIO-MOP just by		In [RFC6550], it was possible to discard an unsupported DIO-MOP just
	inspecting the base message. With this document, the MOPex is a		by inspecting the base message. With this document, the MOPex is a
	different control message option and thus the discarding of the DIO		different control message option and thus the discarding of the DIO
	message could happen after inspecting the message options.		message can only happen after inspecting the message options.
	6. Acknowledgements		6. Acknowledgements
	Using 'I' bit was Pascal Thubert's idea.		Thank you Dominique Barthel for important review/feedback on
			extending Control Options.
	7. IANA Considerations		7. IANA Considerations
	7.1. Mode of operation: MOPex		7.1. Mode of operation: MOPex
	IANA is requested to assign a new Mode of Operation, named "MOPex"		IANA is requested to assign a new Mode of Operation, named "MOPex"
	for MOP extension under the RPL registry. The value of 7 is to be		for MOP extension under the RPL registry. The value of 7 is to be
	assigned from the "Mode of Operation" space [RFC6550]		assigned from the "Mode of Operation" space [RFC6550]
	+-------+-------------+---------------+		+-------+-------------+---------------+
	skipping to change at page 7, line 27 ¶		skipping to change at page 7, line 27 ¶
	may be allocated only by an IETF review. Currently no values are		may be allocated only by an IETF review. Currently no values are
	defined by this document. Each value is tracked with the following		defined by this document. Each value is tracked with the following
	qualities:		qualities:
	o MOPex value		o MOPex value
	o Description		o Description
	o Defining RFC		o Defining RFC
			7.4. Change in RPL Control Option field
			Section 4 of this document specifies MSB of the RPL Control Option to
			be used as a bit to indicate RPL Extended Control Options.
			IANA is requested to reduce the unassigned values range from 0x10 to
			0x7f for RPL Control Options.
			IANA is requested to create a new registry for RPL Extended Control
			Options indicating values 0x80 to 0xff. New values may be allocated
			only by an IETF Review. Each value is tracked with the following
			qualities:
			o Value
			o Meaning
			o Defining RFC
			The value could be in the range of 0x80 to 0xff.
	8. Security Considerations		8. Security Considerations
	The options defined in this document are carried in the base message		The options defined in this document are carried in the base message
	objects as defined in [RFC6550]. The RPL control message options are		objects as defined in [RFC6550]. The RPL control message options are
	protected by the same security mechanisms that protect the base		protected by the same security mechanisms that protect the base
	messages.		messages.
	Capabilities flag can reveal that the node has been upgraded or is		Capabilities flag can reveal that the node has been upgraded or is
	running a old feature set. This document assumes that the base		running a old feature set. This document assumes that the base
	messages that carry these options are protected by RPL security		messages that carry these options are protected by RPL security
	skipping to change at page 8, line 16 ¶		skipping to change at page 8, line 32 ¶
	Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur,		Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur,
	JP., and R. Alexander, "RPL: IPv6 Routing Protocol for		JP., and R. Alexander, "RPL: IPv6 Routing Protocol for
	Low-Power and Lossy Networks", RFC 6550,		Low-Power and Lossy Networks", RFC 6550,
	DOI 10.17487/RFC6550, March 2012,		DOI 10.17487/RFC6550, March 2012,
	<https://www.rfc-editor.org/info/rfc6550>.		<https://www.rfc-editor.org/info/rfc6550>.
	9.2. Informative References		9.2. Informative References
	[I-D.ietf-roll-capabilities]		[I-D.ietf-roll-capabilities]
	Jadhav, R., Thubert, P., Richardson, M., and R. Sahoo,		Jadhav, R., Thubert, P., Richardson, M., and R. Sahoo,
	"RPL Capabilities", draft-ietf-roll-capabilities-06 (work		"RPL Capabilities", draft-ietf-roll-capabilities-07 (work
	in progress), June 2020.		in progress), September 2020.
	Authors' Addresses		Authors' Addresses
	Rahul Arvind Jadhav (editor)		Rahul Arvind Jadhav (editor)
	Huawei Tech		Huawei Tech
	Kundalahalli Village, Whitefield,		Kundalahalli Village, Whitefield,
	Bangalore, Karnataka 560037		Bangalore, Karnataka 560037
	India		India
	Phone: +91-080-49160700		Phone: +91-080-49160700
End of changes. 24 change blocks.
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