< draft-thubert-tree-discovery-06.txt		draft-thubert-tree-discovery-07.txt >
	NEMO Working Group P. Thubert		NEMO Working Group P. Thubert
	Internet-Draft Cisco		Internet-Draft Cisco
	Expires: January 4, 2008 C. Bontoux		Expires: February 2, 2009 C. Bontoux
	Fortinet		Fortinet
	N. Montavont		N. Montavont
	LSIIT - ULP		LSIIT - ULP
	July 3, 2007		B. McCarthy
			Lancaster
			August 1, 2008
	Nested Nemo Tree Discovery		Nested Nemo Tree Discovery
	draft-thubert-tree-discovery-06.txt		draft-thubert-tree-discovery-07.txt
	Status of this Memo		Status of this Memo
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	skipping to change at page 1, line 37 ¶		skipping to change at page 1, line 39 ¶
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	Copyright Notice		Copyright Notice
	Copyright (C) The IETF Trust (2007).		Copyright (C) The IETF Trust (2008).
	Abstract		Abstract
	This paper describes a simple distance vector protocol that exposes		This paper describes a simple distance vector protocol that exposes
	only a default route towards the infrastructure in a nested NEMO		only a default route towards the infrastructure in a nested NEMO
	configuration. The draft extends the Neighbor Discovery Protocol [1]		configuration. The draft extends the Neighbor Discovery Protocol [1]
	in order to carry information and metrics which will help a Mobile		in order to carry information and metrics which will help a Mobile
	Router select its Attachment Router(s) in an autonomous fashion and		Router select its Attachment Router(s) in an autonomous fashion and
	provides generic rules which guarantee that the interaction of		provides generic rules which guarantee that the interaction of
	different selection processes will not create loops.		different selection processes will not create loops.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5
	2. Terms and Abbreviations . . . . . . . . . . . . . . . . . . . 4		2. Terms and Abbreviations . . . . . . . . . . . . . . . . . . . 5
	3. Motivations . . . . . . . . . . . . . . . . . . . . . . . . . 5		3. Motivations . . . . . . . . . . . . . . . . . . . . . . . . . 6
	3.1. Multi-Homed nested mobile network . . . . . . . . . . . . 5		3.1. Multi-Homed nested mobile network . . . . . . . . . . . . 6
	3.2. Loops in nested Nemo . . . . . . . . . . . . . . . . . . . 6		3.2. Loops in nested Nemo . . . . . . . . . . . . . . . . . . . 7
	4. Tree Information Option . . . . . . . . . . . . . . . . . . . 8		4. Tree Information Option . . . . . . . . . . . . . . . . . . . 9
	4.1. TIO base option . . . . . . . . . . . . . . . . . . . . . 8		4.1. TIO base option . . . . . . . . . . . . . . . . . . . . . 9
	4.2. TIO suboptions . . . . . . . . . . . . . . . . . . . . . . 11		4.2. TIO suboptions . . . . . . . . . . . . . . . . . . . . . . 12
	4.2.1. Format . . . . . . . . . . . . . . . . . . . . . . . . 11		4.2.1. Format . . . . . . . . . . . . . . . . . . . . . . . . 12
	4.2.2. Pad1 . . . . . . . . . . . . . . . . . . . . . . . . . 11		4.2.2. Pad1 . . . . . . . . . . . . . . . . . . . . . . . . . 12
	4.2.3. PadN . . . . . . . . . . . . . . . . . . . . . . . . . 12		4.2.3. PadN . . . . . . . . . . . . . . . . . . . . . . . . . 13
	4.2.4. Bandwidth Suboption . . . . . . . . . . . . . . . . . 12		4.2.4. Bandwidth Suboption . . . . . . . . . . . . . . . . . 13
	4.2.5. Stable time Suboption . . . . . . . . . . . . . . . . 13		4.2.5. Stable time Suboption . . . . . . . . . . . . . . . . 14
	4.2.6. Tree Group ID Suboption . . . . . . . . . . . . . . . 14		4.2.6. Tree Group ID Suboption . . . . . . . . . . . . . . . 15
	4.2.7. Path Free Medium Time Suboption . . . . . . . . . . . 14		4.2.7. Path Free Medium Time Suboption . . . . . . . . . . . 15
	4.2.8. Uniform Path Metric Suboption . . . . . . . . . . . . 15		4.2.8. Uniform Path Metric Suboption . . . . . . . . . . . . 16
	5. Tree Discovery . . . . . . . . . . . . . . . . . . . . . . . . 17		5. Tree Discovery . . . . . . . . . . . . . . . . . . . . . . . . 17
	5.1. tree selection . . . . . . . . . . . . . . . . . . . . . . 18		5.1. tree selection . . . . . . . . . . . . . . . . . . . . . . 18
	5.2. Sub-tree mobility . . . . . . . . . . . . . . . . . . . . 19		5.2. Sub-tree mobility . . . . . . . . . . . . . . . . . . . . 19
	5.3. Administrative depth . . . . . . . . . . . . . . . . . . . 20		5.3. Administrative depth . . . . . . . . . . . . . . . . . . . 20
	5.4. DRL entries states and stability . . . . . . . . . . . . . 20		5.4. DRL entries states and stability . . . . . . . . . . . . . 20
	5.4.1. Held-Up . . . . . . . . . . . . . . . . . . . . . . . 20		5.4.1. Held-Up . . . . . . . . . . . . . . . . . . . . . . . 20
	5.4.2. Held-Down . . . . . . . . . . . . . . . . . . . . . . 21		5.4.2. Held-Down . . . . . . . . . . . . . . . . . . . . . . 21
	5.4.3. Collision . . . . . . . . . . . . . . . . . . . . . . 21		5.4.3. Collision . . . . . . . . . . . . . . . . . . . . . . 21
	5.4.4. Instability . . . . . . . . . . . . . . . . . . . . . 22		5.4.4. Instability . . . . . . . . . . . . . . . . . . . . . 22
			5.4.5. Density . . . . . . . . . . . . . . . . . . . . . . . 23
	5.5. Legacy Routers . . . . . . . . . . . . . . . . . . . . . . 23		5.5. Legacy Routers . . . . . . . . . . . . . . . . . . . . . . 23
	6. Directed Acyclic Graph Discovery . . . . . . . . . . . . . . . 23		6. Directed Acyclic Graph Discovery . . . . . . . . . . . . . . . 23
	7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23		7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24
	8. Security Considerations . . . . . . . . . . . . . . . . . . . 23		8. Security Considerations . . . . . . . . . . . . . . . . . . . 24
	9. Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . 24		9. Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
	9.1. Changes from version 00 to 01 . . . . . . . . . . . . . . 24		9.1. Changes from version 00 to 01 . . . . . . . . . . . . . . 24
	9.2. Changes from version 01 to 02 . . . . . . . . . . . . . . 24		9.2. Changes from version 01 to 02 . . . . . . . . . . . . . . 24
	9.3. Changes from version 02 to 03 . . . . . . . . . . . . . . 24		9.3. Changes from version 02 to 03 . . . . . . . . . . . . . . 24
	9.4. Changes from version 03 to 04 . . . . . . . . . . . . . . 24		9.4. Changes from version 03 to 04 . . . . . . . . . . . . . . 25
	9.5. Changes from version 04 to 05 . . . . . . . . . . . . . . 24		9.5. Changes from version 04 to 05 . . . . . . . . . . . . . . 25
	9.6. Changes from version 05 to 06 . . . . . . . . . . . . . . 24		9.6. Changes from version 05 to 06 . . . . . . . . . . . . . . 25
	10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 25		10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 25
	11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 26		11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 26
	11.1. Normative Reference . . . . . . . . . . . . . . . . . . . 26		11.1. Normative Reference . . . . . . . . . . . . . . . . . . . 26
	11.2. Informative Reference . . . . . . . . . . . . . . . . . . 26		11.2. Informative Reference . . . . . . . . . . . . . . . . . . 26
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 27		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 27
	Intellectual Property and Copyright Statements . . . . . . . . . . 28		Intellectual Property and Copyright Statements . . . . . . . . . . 28
	skipping to change at page 14, line 50 ¶		skipping to change at page 15, line 50 ¶
	This suboption carries the Free Medium Time available up the tree via		This suboption carries the Free Medium Time available up the tree via
	a specific parent at a given point of time. It is an indication of		a specific parent at a given point of time. It is an indication of
	whether bandwidth is available to place VoIP calls for instance. As		whether bandwidth is available to place VoIP calls for instance. As
	defined by the Quality of Service (QoS) Task Group of the Wi-Fi		defined by the Quality of Service (QoS) Task Group of the Wi-Fi
	Alliance, the Medium Time describes the amount of time admitted to		Alliance, the Medium Time describes the amount of time admitted to
	access the medium, in units of 32 microsecond periods per second.		access the medium, in units of 32 microsecond periods per second.
	The Free Medium Time is the amount of time left the medium, in other		The Free Medium Time is the amount of time left the medium, in other
	words ((1000000/32) - SIGMA(MT)). The Path Free Medium Time is the		words ((1000000/32) - SIGMA(MT)). The Path Free Medium Time is the
	lowest available Free Medium Time along the way and it reflects the		lowest available Free Medium Time along the way and it reflects the
	actual use of those links in run time.		actual use of those links in run time. The Path Free Medium Time
			suboption does not have any alignment requirements. Its format is as
	The Path Free Medium Time suboption does not have any alignment		follows:
	requirements. Its format is as follows:
	0 1 2 3		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 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 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Type = 5 | Length = 2 | Path Free Medium Time |		| Type = 5 | Length = 2 | Path Free Medium Time |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Figure 8: Path Free Medium Time Suboption		Figure 8: Path Free Medium Time Suboption
	Type: Set to 5 for the Path Free Medium Time Suboption.		Type: Set to 5 for the Path Free Medium Time Suboption.
	skipping to change at page 15, line 30 ¶		skipping to change at page 16, line 29 ¶
	microsecond periods per second. The clusterhead initializes that		microsecond periods per second. The clusterhead initializes that
	field to the Free MT on the link where the TIO is issued. An		field to the Free MT on the link where the TIO is issued. An
	attached MR propagates it as the minimum of the Path Free MT as		attached MR propagates it as the minimum of the Path Free MT as
	received in the TIO from the parent and the Path Free MT on the		received in the TIO from the parent and the Path Free MT on the
	link on which the TIO is propagated. As a result, the value		link on which the TIO is propagated. As a result, the value
	received from a candidate AR is that of the bottleneck between		received from a candidate AR is that of the bottleneck between
	that AR and the clusterhead.		that AR and the clusterhead.
	4.2.8. Uniform Path Metric Suboption		4.2.8. Uniform Path Metric Suboption
	This suboption carries the Uniform Path Metric for the path along the		This suboption carries the Uniform Path Metric (UPM) for the path
	tree. It is set to zero by the clusterhead and incremented as the		along the tree. It is set to zero by the clusterhead and incremented
	TIO is propagated down the tree. The Uniform Path Metric Suboption		as the TIO is propagated down the tree. The Uniform Path Metric
	has an alignment requirement of 4n+2. Its format is as follows:		Suboption has an alignment requirement of 4n+2. Its format is as
			follows:
	0 1 2 3		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 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 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Type = 6 | Length = 4 |		| Type = 6 | Length = 4 |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Uniform Path Metric |		| Uniform Path Metric |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Figure 9: Uniform Path Metric Suboption		Figure 9: Uniform Path Metric Suboption
	Type: 8-bit unsigned integer. Its value is 6 for the Uniform Path		Type: 8-bit unsigned integer. Its value is 6 for this suboption.
	Metric.
	Length: 8-bit unsigned integer. Its value is 4 for the Uniform Path		Length: 8-bit unsigned integer. Its value is 4 for this suboption.
	Metric suboption.
	Uniform Path Metric: 32-bit unsigned integer aggragating the cost of		Uniform Path Metric: 32-bit unsigned integer aggregating the cost of
	multiple radio hops.		radio hops.
	5. Tree Discovery		5. Tree Discovery
	Tree Discovery is a form of distance vector protocol for use in		Tree Discovery is a form of distance vector protocol for use in
	wireless mesh networks. TD locates the nearest exit and forms a		wireless mesh networks. TD locates the nearest exit and forms a
	Directed Acyclic Graphs towards that exit, usually a tree. TD		Directed Acyclic Graphs towards that exit, usually a tree. TD
	enables Mobile Routers to implement different policies for selecting		enables Mobile Routers to implement different policies for selecting
	their preferred parent in the Tree by introducing the concept of		their preferred parent in the Tree by introducing the concept of
	plug-in, and does not specify the plug-in operation. Rather, TD		plug-in, and does not specify the plug-in operation. Rather, TD
	specifies a set of rules to be implemented by all plug-ins to ensure		specifies a set of rules to be implemented by all plug-ins to ensure
	skipping to change at page 23, line 10 ¶		skipping to change at page 23, line 10 ¶
	Down.		Down.
	Instability is transient (in the order of tree hop timers). When a		Instability is transient (in the order of tree hop timers). When a
	Mobile Router is unstable, it MUST NOT send RAs with TIO. This		Mobile Router is unstable, it MUST NOT send RAs with TIO. This
	avoids loops when Mobile Router A wishes to attach to Mobile Router B		avoids loops when Mobile Router A wishes to attach to Mobile Router B
	and Mobile Router B wishes to attach to Mobile Router A. Unless RA		and Mobile Router B wishes to attach to Mobile Router A. Unless RA
	cross (see Collision section), a Mobile Router receives TIO from		cross (see Collision section), a Mobile Router receives TIO from
	stable Attachment Routers, which do not plan to attach to itself, so		stable Attachment Routers, which do not plan to attach to itself, so
	the Mobile Router can safely attach to them.		the Mobile Router can safely attach to them.
			5.4.5. Density
			In a dense environment, it is useless that all routers that can
			provide backhauling service actually do so; in practice, limiting the
			number of routers that accept visitors saves memory in the visitors
			and reduces the cost of signalling. Also, limiting the number of
			nodes (mobile routers that is) in the tree improves the multicast
			operations.
			Algorithms such a Trickle could be used by a Mobile Router to decide
			to stop providing its access services for visitors if there are a
			number of neighboring routers that provide similar services. The
			simplest abstraction of such similarity is that a multiple routers
			advertising a same depth, though such a simple similarity does not
			address the specifics of a router selection in the plugins. In a
			more general fashion, a Mobile Router can associate the concept of
			similarity with the characteristics of its own attachment router
			selection plug in.
	5.5. Legacy Routers		5.5. Legacy Routers
	A legacy router sends its Router Advertisements without a TIO.		A legacy router sends its Router Advertisements without a TIO.
	Consequently, a legacy router can be mistaken for a fixed Access		Consequently, a legacy router can be mistaken for a fixed Access
	Router when it is placed within a nested NEMO structure, and defeat		Router when it is placed within a nested NEMO structure, and defeat
	the loop avoidance mechanism. Consequently, it is important for the		the loop avoidance mechanism. Consequently, it is important for the
	administrator to prevent address autoconfiguration by visiting Mobile		administrator to prevent address autoconfiguration by visiting Mobile
	Routers from such a legacy router.		Routers from such a legacy router.
	6. Directed Acyclic Graph Discovery		6. Directed Acyclic Graph Discovery
	skipping to change at page 25, line 13 ¶		skipping to change at page 25, line 32 ¶
	depth vs. the plug-ins.		depth vs. the plug-ins.
	10. Acknowledgments		10. Acknowledgments
	The authors wish to thank Marco Molteni and Patrick Wetterwald		The authors wish to thank Marco Molteni and Patrick Wetterwald
	(cisco) for their participation to this design and the review of the		(cisco) for their participation to this design and the review of the
	document, Massimo Villari (university of Messina), for his early work		document, Massimo Villari (university of Messina), for his early work
	on simulation and research on the subject and Julien Abeille for his		on simulation and research on the subject and Julien Abeille for his
	advanced participation in simulation and real testing. Also the		advanced participation in simulation and real testing. Also the
	authors wish to thank Christopher Dearlove for his suggestion for		authors wish to thank Christopher Dearlove for his suggestion for
	additional protection against loops in TD. This work is also based		additional protection against loops in TD, and Philip Levis, David
	on prior publications, in particular HMRA [6] by Hosik Cho and Eun-		Cueller and Jonathan Hui for the suggestions about Trickle. This
	Kyoung Paik from Seoul National University and other non IETF		work is also based on prior publications, in particular HMRA [6] by
	publications coauthored with Thierry Ernst and Thomas Noel. Finally,		Hosik Cho and Eun-Kyoung Paik from Seoul National University and
	the authors heartily thank Marcelo Bagnulo Braun and Teco Boot for		other non IETF publications coauthored with Thierry Ernst and Thomas
	their very constructive reviews.		Noel. Finally, the authors heartily thank Marcelo Bagnulo Braun and
			Teco Boot for their very constructive reviews.
	11. References		11. References
	11.1. Normative Reference		11.1. Normative Reference
	[1] Narten, T., Nordmark, E., and W. Simpson, "Neighbor Discovery		[1] Narten, T., Nordmark, E., and W. Simpson, "Neighbor Discovery
	for IP Version 6 (IPv6)", RFC 2461, December 1998.		for IP Version 6 (IPv6)", RFC 2461, December 1998.
	[2] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in		[2] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in
	IPv6", RFC 3775, June 2004.		IPv6", RFC 3775, June 2004.
	skipping to change at page 28, line 5 ¶		skipping to change at page 27, line 37 ¶
	LSIIT - Univerity Louis Pasteur		LSIIT - Univerity Louis Pasteur
	Pole API, bureau C444		Pole API, bureau C444
	Boulevard Sebastien Brant		Boulevard Sebastien Brant
	Illkirch 67400		Illkirch 67400
	FRANCE		FRANCE
	Phone: (33) 3 90 24 45 87		Phone: (33) 3 90 24 45 87
	Email: montavont@dpt-info.u-strasbg.fr		Email: montavont@dpt-info.u-strasbg.fr
	URI: http://www-r2.u-strasbg.fr/~montavont/		URI: http://www-r2.u-strasbg.fr/~montavont/
			Ben McCarthy
			Lancaster University
			Computing Department
			Infolab21, South Drive
			Lancaster University
			Lancaster LA1 4WA
			UK
			Phone: +44 1524 510 383
			Email: b.mccarthy@lancaster.ac.uk
	Full Copyright Statement		Full Copyright Statement
	Copyright (C) The IETF Trust (2007).		Copyright (C) The IETF Trust (2008).
	This document is subject to the rights, licenses and restrictions		This document is subject to the rights, licenses and restrictions
	contained in BCP 78, and except as set forth therein, the authors		contained in BCP 78, and except as set forth therein, the authors
	retain all their rights.		retain all their rights.
	This document and the information contained herein are provided on an		This document and the information contained herein are provided on an
	"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS		"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
	OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND		OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
	THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS		THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
	OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF		OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
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