< draft-ietf-bfd-multipoint-11.txt		draft-ietf-bfd-multipoint-12.txt >
	Internet Engineering Task Force D. Katz		Internet Engineering Task Force D. Katz
	Internet-Draft Juniper Networks		Internet-Draft Juniper Networks
	Intended status: Standards Track D. Ward		Intended status: Standards Track D. Ward
	Expires: June 14, 2018 Cisco Systems		Expires: June 17, 2018 Cisco Systems
	S. Pallagatti, Ed.		S. Pallagatti, Ed.
	Individual contributor		Individual contributor
	December 11, 2017		G. Mirsky, Ed.
			ZTE Corp.
			December 14, 2017
	BFD for Multipoint Networks		BFD for Multipoint Networks
	draft-ietf-bfd-multipoint-11		draft-ietf-bfd-multipoint-12
	Abstract		Abstract
	This document describes extensions to the Bidirectional Forwarding		This document describes extensions to the Bidirectional Forwarding
	Detection (BFD) protocol for its use in multipoint and multicast		Detection (BFD) protocol for its use in multipoint and multicast
	networks. Comments on this draft should be directed to rtg-		networks. Comments on this draft should be directed to rtg-
	bfd@ietf.org.		bfd@ietf.org.
	Requirements Language		Requirements Language
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this		"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
	document are to be interpreted as described in RFC 2119 [RFC2119].		"OPTIONAL" in this document are to be interpreted as described in BCP
			14 [RFC2119] [RFC8174] when, and only when, they appear in all
			capitals, as shown here.
	Status of This Memo		Status of This Memo
	This Internet-Draft is submitted in full conformance with the		This Internet-Draft is submitted in full conformance with the
	provisions of BCP 78 and BCP 79.		provisions of BCP 78 and BCP 79.
	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 June 14, 2018.		This Internet-Draft will expire on June 17, 2018.
	Copyright Notice		Copyright Notice
	Copyright (c) 2017 IETF Trust and the persons identified as the		Copyright (c) 2017 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 27 ¶
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	described in the Simplified BSD License.		described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
	2. Goals . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3		2. Goals . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
	3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 4		3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 4
	4. Protocol Details . . . . . . . . . . . . . . . . . . . . . . 4		4. Protocol Details . . . . . . . . . . . . . . . . . . . . . . 4
	4.1. Multipoint BFD Control Packets . . . . . . . . . . . . . 4		4.1. Multipoint BFD Control Packets . . . . . . . . . . . . . 4
	4.2. Session Model . . . . . . . . . . . . . . . . . . . . . . 4		4.2. Session Model . . . . . . . . . . . . . . . . . . . . . . 5
	4.3. Session Failure Semantics . . . . . . . . . . . . . . . . 5		4.3. Session Failure Semantics . . . . . . . . . . . . . . . . 5
	4.4. State Variables . . . . . . . . . . . . . . . . . . . . . 5		4.4. State Variables . . . . . . . . . . . . . . . . . . . . . 5
	4.4.1. New State Variables . . . . . . . . . . . . . . . . . 5		4.4.1. New State Variables . . . . . . . . . . . . . . . . . 5
	4.4.2. State Variable Initialization and Maintenance . . . . 6		4.4.2. State Variable Initialization and Maintenance . . . . 6
	4.5. State Machine . . . . . . . . . . . . . . . . . . . . . . 6		4.5. State Machine . . . . . . . . . . . . . . . . . . . . . . 6
	4.6. Session Establishment . . . . . . . . . . . . . . . . . . 7		4.6. Session Establishment . . . . . . . . . . . . . . . . . . 7
	4.7. Discriminators and Packet Demultiplexing . . . . . . . . 7		4.7. Discriminators and Packet Demultiplexing . . . . . . . . 7
	4.8. Packet consumption on tails . . . . . . . . . . . . . . . 8		4.8. Packet consumption on tails . . . . . . . . . . . . . . . 8
	4.9. Bringing Up and Shutting Down Multipoint BFD Service . . 8		4.9. Bringing Up and Shutting Down Multipoint BFD Service . . 8
	4.10. Timer Manipulation . . . . . . . . . . . . . . . . . . . 8		4.10. Timer Manipulation . . . . . . . . . . . . . . . . . . . 9
	4.11. Detection Times . . . . . . . . . . . . . . . . . . . . . 9		4.11. Detection Times . . . . . . . . . . . . . . . . . . . . . 9
	4.12. State Maintenance for Down/AdminDown Sessions . . . . . . 9		4.12. State Maintenance for Down/AdminDown Sessions . . . . . . 9
	4.12.1. MultipointHead Sessions . . . . . . . . . . . . . . 9		4.12.1. MultipointHead Sessions . . . . . . . . . . . . . . 10
	4.12.2. MultipointTail Sessions . . . . . . . . . . . . . . 9		4.12.2. MultipointTail Sessions . . . . . . . . . . . . . . 10
	4.13. Base Specification Text Replacement . . . . . . . . . . . 10		4.13. Base Specification Text Replacement . . . . . . . . . . . 10
	4.13.1. Reception of BFD Control Packets . . . . . . . . . . 10		4.13.1. Reception of BFD Control Packets . . . . . . . . . . 10
	4.13.2. Demultiplexing BFD Control Packets . . . . . . . . . 12		4.13.2. Demultiplexing BFD Control Packets . . . . . . . . . 13
	4.13.3. Transmitting BFD Control Packets . . . . . . . . . . 13		4.13.3. Transmitting BFD Control Packets . . . . . . . . . . 14
	5. Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . 16		5. Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . 16
	6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16		6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
	7. Security Considerations . . . . . . . . . . . . . . . . . . . 16		7. Security Considerations . . . . . . . . . . . . . . . . . . . 17
	8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 17		8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 17
	9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 17		9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 17
	10. Normative References . . . . . . . . . . . . . . . . . . . . 17		10. Normative References . . . . . . . . . . . . . . . . . . . . 17
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18
	1. Introduction		1. Introduction
	The Bidirectional Forwarding Detection protocol [RFC5880] specifies a		The Bidirectional Forwarding Detection protocol [RFC5880] specifies a
	method for verifying unicast connectivity between a pair of systems.		method for verifying unicast connectivity between a pair of systems.
	This document defines a method for using BFD to provide verification		This document defines a method for using BFD to provide verification
	of multipoint or multicast connectivity between a multipoint sender		of multipoint or multicast connectivity between a multipoint sender
	(the "head") and a set of one or more multipoint receivers (the		(the "head") and a set of one or more multipoint receivers (the
	"tails").		"tails").
	As multipoint transmissions are inherently unidirectional, this		As multipoint transmissions are inherently unidirectional, this
	mechanism purports only to verify this unidirectional connectivity.		mechanism purports only to verify this unidirectional connectivity.
	Although this seems in conflict with the "Bidirectional" in BFD, it		Although this seems in conflict with the "Bidirectional" in BFD, the
	is a natural fit for that protocol.		protocol is capable supporting this use case.
	This application of BFD allows for the tails to detect a lack of		This application of BFD allows for the tails to detect a lack of
	connectivity from the head. Due to unidirectional nature, virtually		connectivity from the head. Due to unidirectional nature, virtually
	all options and timing parameters are controlled by the head.		all options and timing parameters are controlled by the head.
	As an option, the tail may notify the head of the lack of multipoint		As an option, the tail may notify the head of the lack of multipoint
	connectivity. Details of tail notification to head are outside the		connectivity. Details of tail notification to head are outside the
	scope of this document.		scope of this document.
	Throughout this document, the term "multipoint" is defined as a		Throughout this document, the term "multipoint" is defined as a
	mechanism by which one or more systems receive packets sent by a		mechanism by which one or more systems receive packets sent by a
	single sender. This specifically includes such things as IP		single sender. This specifically includes such things as IP
	multicast and point-to-multipoint MPLS.		multicast and point-to-multipoint MPLS.
			Term "connectivity" in this document is not being used in context of
			connectivity verification in transport network but as an alternative
			to "continuity", i.e. existence of a path between the sender and the
			receiver.
	This document effectively modifies and adds to the base BFD		This document effectively modifies and adds to the base BFD
	specification. It is the intention of the authors to fold these		specification. It is the intention of the authors to fold these
	extensions into the base specification at the appropriate time.		extensions into the base specification at the appropriate time.
	2. Goals		2. Goals
	The primary goal of this mechanism is to allow tails to rapidly		The primary goal of this mechanism is to allow tails to rapidly
	detect the fact that multipoint connectivity from the head has		detect the fact that multipoint connectivity from the head has
	failed.		failed.
	skipping to change at page 4, line 7 ¶		skipping to change at page 4, line 12 ¶
	A further goal is to support multiple, overlapping multipoint paths,		A further goal is to support multiple, overlapping multipoint paths,
	as well as multipoint paths with multiple heads, and to allow point-		as well as multipoint paths with multiple heads, and to allow point-
	to-point BFD sessions to operate simultaneously among the systems		to-point BFD sessions to operate simultaneously among the systems
	participating in Multipoint BFD.		participating in Multipoint BFD.
	A final goal is to integrate multipoint operation into the base		A final goal is to integrate multipoint operation into the base
	specification in such a way as to make it relatively easy to support		specification in such a way as to make it relatively easy to support
	both multipoint and point-to-point operation in a single		both multipoint and point-to-point operation in a single
	implementation.		implementation.
	It is a non-goal for this protocol to verify point-to-point		It is a non-goal for this protocol to verify point-to-point bi-
	connectivity between the head and any tails. This can be done		directional connectivity between the head and any tails. This can be
	independently (and with no penalty in protocol overhead) by using		done independently (and with no penalty in protocol overhead) by
	point-to-point BFD.		using point-to-point BFD.
	3. Overview		3. Overview
	The heart of this protocol is the periodic transmission of BFD		The heart of this protocol is the periodic transmission of BFD
	Control packets along a multipoint path, from the head to all tails		Control packets along a multipoint path, from the head to all tails
	on the tree. The contents of the BFD packets provide the means for		on the tree. The contents of the BFD packets provide the means for
	the tails to calculate the detection time for path failure. If no		the tails to calculate the detection time for path failure. If no
	BFD Control packets are received by a tail for a detection time, the		BFD Control packets are received by a tail for a detection time, the
	tail declares the path to have failed. For some applications this is		tail declares the path to have failed. For some applications this is
	the only mechanism necessary; the head can remain ignorant of the		the only mechanism necessary; the head can remain ignorant of the
	skipping to change at page 5, line 5 ¶		skipping to change at page 5, line 10 ¶
	the M bit. This means that Multipoint BFD does not depend on the		the M bit. This means that Multipoint BFD does not depend on the
	recipient of a packet to know whether the packet was received over a		recipient of a packet to know whether the packet was received over a
	multipoint path. This can be useful in scenarios where this		multipoint path. This can be useful in scenarios where this
	information may not be available to the recipient.		information may not be available to the recipient.
	4.2. Session Model		4.2. Session Model
	Multipoint BFD is modeled as a set of sessions of different types.		Multipoint BFD is modeled as a set of sessions of different types.
	The elements of procedure differ slightly for each type.		The elements of procedure differ slightly for each type.
	Point-to-point sessions, as described in [BFD], are of type		Point-to-point sessions, as described in [RFC5880], are of type
	PointToPoint.		PointToPoint.
	The head has a session of type MultipointHead that is bound to a		The head has a session of type MultipointHead that is bound to a
	multipoint path. Multipoint BFD Control packets are sent by this		multipoint path. Multipoint BFD Control packets are sent by this
	session over the multipoint path, and no BFD Control packets are		session over the multipoint path, and no BFD Control packets are
	received by it.		received by it.
	Each tail has a session of type MultipointTail associated with a		Each tail has a session of type MultipointTail associated with a
	multipoint path. These sessions receive BFD Control packets from the		multipoint path. These sessions receive BFD Control packets from the
	head over multipoint path.		head over multipoint path.
	skipping to change at page 7, line 47 ¶		skipping to change at page 8, line 7 ¶
	and with Your Discr set to zero.		and with Your Discr set to zero.
	IP and MPLS multipoint tails MUST demultiplex BFD packets based on a		IP and MPLS multipoint tails MUST demultiplex BFD packets based on a
	combination of the source address, My Discriminator and the identity		combination of the source address, My Discriminator and the identity
	of the multipoint tree which the Multipoint BFD Control packet was		of the multipoint tree which the Multipoint BFD Control packet was
	received from. Together they uniquely identify the head of the		received from. Together they uniquely identify the head of the
	multipoint path. Bootstrapping BFD session to a multipoint LSP in		multipoint path. Bootstrapping BFD session to a multipoint LSP in
	case of penultimate hop popping is outside the scope of this		case of penultimate hop popping is outside the scope of this
	document.		document.
	Note that, unlike PointToPoint sessions, the discriminator values on		Note that, unlike PointToPoint sessions, the My Discriminator value
	all multipoint session types MUST NOT be changed during the life of a		on MultipointHead session MUST NOT be changed during the life of a
	session. This is a side effect of the more complex demultiplexing		session. This is a side effect of the more complex demultiplexing
	scheme.		scheme.
	4.8. Packet consumption on tails		4.8. Packet consumption on tails
	BFD packets received on tails for a multicast group MUST be consumed		BFD packets received on tails for a multicast group MUST be consumed
	by tails and MUST not be forwarded to receivers. Session of type		by tails and MUST NOT be forwarded to receivers. Session of type
	MultipointTail MUST identify the packet as BFD with the help of		MultipointTail MUST identify the packet as BFD with the help of
	destination UDP port number "3784" on IP multipoint path. For		destination UDP port number "3784" on IP multipoint path.
	multipoint LSP, MultipointTail MUST use destination UDP port "3784"
	and IP "127.0.0.0/8" range. Packet identified as BFD packet MUST be		For multipoint LSP, when IP/UDP encapsulation of BFD control packet
	consumed by MultipointTail and demultiplex as described in		used, MultipointTail MUST use destination UDP port "3784" and
	Section 4.13.2		"127.0.0.0/8" range for IPv4 or "0:0:0:0:0:FFFF:7F00:0/104" range for
			IPv6. Packet identified as BFD packet MUST be consumed by
			MultipointTail and demultiplex as described in Section 4.13.2. Use
			of other types of encapsulation for multipoint LSP is outside the
			scope of this document.
	4.9. Bringing Up and Shutting Down Multipoint BFD Service		4.9. Bringing Up and Shutting Down Multipoint BFD Service
	Because there is no three-way handshake in Multipoint BFD, a newly		Because there is no three-way handshake in Multipoint BFD, a newly
	started head (that does not have any previous state information		started head (that does not have any previous state information
	available) SHOULD start with bfd.SessionState set to Down and with		available) SHOULD start with bfd.SessionState set to Down and with
	bfd.RequiredMinRxInterval set to zero in the MultipointHead session.		bfd.RequiredMinRxInterval set to zero in the MultipointHead session.
	The session SHOULD remain in this state for a time equal to		The session SHOULD remain in this state for a time equal to
	(bfd.DesiredMinTxInterval * bfd.DetectMult). This will ensure that		(bfd.DesiredMinTxInterval * bfd.DetectMult). This will ensure that
	all MultipointTail sessions are reset (so long as the restarted head		all MultipointTail sessions are reset (so long as the restarted head
	skipping to change at page 9, line 5 ¶		skipping to change at page 9, line 17 ¶
	4.10. Timer Manipulation		4.10. Timer Manipulation
	Because of the one-to-many mapping, a session of type MultipointHead		Because of the one-to-many mapping, a session of type MultipointHead
	SHOULD NOT initiate a Poll Sequence in conjunction with timer value		SHOULD NOT initiate a Poll Sequence in conjunction with timer value
	changes. However to indicate change in packet MultipointHead session		changes. However to indicate change in packet MultipointHead session
	MUST send packet with P bit set. MultipointTail session MUST NOT		MUST send packet with P bit set. MultipointTail session MUST NOT
	reply if packet has M, P bit set and bfd.RequiredMinRxInterval set to		reply if packet has M, P bit set and bfd.RequiredMinRxInterval set to
	0.		0.
	The MultipointHead MUST send bfd.DetectMult packets with P bit set at		The MultipointHead, when changing the transmit interval to higher
	the old transmit interval before using the higher value in order to		value, MUST send BFD control packets with P bit set at the old
	avoid false detection timeouts at the tails. MultipointHead May also		transmit interval before using the higher value in order to avoid
	wait some amount of time before making the changes to the transmit		false detection timeouts at the tails. MultipointHead MAY also wait
			some amount of time before making the changes to the transmit
	interval (through configuration).		interval (through configuration).
	Change in the value of bfd.RequiredMinRxInterval is outside the scope		Change in the value of bfd.RequiredMinRxInterval is outside the scope
	of this document.		of this document.
	4.11. Detection Times		4.11. Detection Times
	Multipoint BFD is inherently asymmetric. As such, each session type		Multipoint BFD is inherently asymmetric. As such, each session type
	has a different approach to detection times.		has a different approach to detection times.
	skipping to change at page 14, line 20 ¶		skipping to change at page 14, line 37 ¶
	A system MUST NOT periodically transmit BFD Control packets if		A system MUST NOT periodically transmit BFD Control packets if
	bfd.RemoteMinRxInterval is zero.		bfd.RemoteMinRxInterval is zero.
	If bfd.SessionType is MultipointHead, the transmit interval MUST be		If bfd.SessionType is MultipointHead, the transmit interval MUST be
	set to bfd.DesiredMinTxInterval (this should happen automatically, as		set to bfd.DesiredMinTxInterval (this should happen automatically, as
	bfd.RemoteMinRxInterval will be zero.)		bfd.RemoteMinRxInterval will be zero.)
	If bfd.SessionType is not MultipointHead, the transmit interval MUST		If bfd.SessionType is not MultipointHead, the transmit interval MUST
	be recalculated whenever bfd.DesiredMinTxInterval changes, or		be recalculated whenever bfd.DesiredMinTxInterval changes, or
	whenever bfd.RemoteMinRxInterval changes, and is equal to the greater		whenever bfd.RemoteMinRxInterval changes, and is equal to the greater
	of those two values. See [BFD] sections 6.8.2 and 6.8.3 for details		of those two values. See [RFC5880] sections 6.8.2 and 6.8.3 for
	on transmit timers.		details on transmit timers.
	A system MUST NOT set the Demand (D) bit if bfd.SessionType is		A system MUST NOT set the Demand (D) bit if bfd.SessionType is
	MultipointTail.		MultipointTail.
	A system MUST NOT set the Demand (D) bit if bfd.SessionType		A system MUST NOT set the Demand (D) bit if bfd.SessionType
	PointToPoint unless bfd.DemandMode is 1, bfd.SessionState is Up, and		PointToPoint unless bfd.DemandMode is 1, bfd.SessionState is Up, and
	bfd.RemoteSessionState is Up.		bfd.RemoteSessionState is Up.
	If bfd.SessionType is PointToPoint or MultipointHead, a BFD Control		If bfd.SessionType is PointToPoint or MultipointHead, a BFD Control
	packet SHOULD be transmitted during the interval between periodic		packet SHOULD be transmitted during the interval between periodic
	skipping to change at page 16, line 36 ¶		skipping to change at page 17, line 7 ¶
	If authentication is in use, all tails must be configured to have a		If authentication is in use, all tails must be configured to have a
	common authentication key in order to receive the multipoint BFD		common authentication key in order to receive the multipoint BFD
	Control packets.		Control packets.
	6. IANA Considerations		6. IANA Considerations
	This document has no actions for IANA.		This document has no actions for IANA.
	7. Security Considerations		7. Security Considerations
	Implementations that creates MultpointTail sessions dynamically upon		Implementations that create MultpointTail sessions dynamically upon
	receipt of Multipoint BFD Control packets MUST implement protective		receipt of Multipoint BFD Control packets MUST implement protective
	measures to prevent infinite number of MultipointTail session being		measures to prevent infinite number of MultipointTail sessions being
	created. Below lists some points to be considered in such		created. Below are listed some points to be considered in such
	implementations.		implementations.
	If a Multipoint BFD Control packet did not arrive on a multicast		If a Multipoint BFD Control packet did not arrive on a multicast
	tree (ex: on expected interface, with expected MPLS label, etc),		tree (ex: on expected interface, with expected MPLS label, etc),
	then a MultipointTail session should not be created.		then a MultipointTail session should not be created.
	If redundant streams are expected for a given multicast stream,		If redundant streams are expected for a given multicast stream,
	then the implementations should not create more MultipointTail		then the implementations should not create more MultipointTail
	sessions than the number of streams. Additionally, when the		sessions than the number of streams. Additionally, when the
	number of MultipointTail sessions exceeds the number of expected		number of MultipointTail sessions exceeds the number of expected
	skipping to change at page 17, line 33 ¶		skipping to change at page 18, line 5 ¶
	[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>.
	[RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection		[RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
	(BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,		(BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
	<https://www.rfc-editor.org/info/rfc5880>.		<https://www.rfc-editor.org/info/rfc5880>.
			[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
			2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
			May 2017, <https://www.rfc-editor.org/info/rfc8174>.
	Authors' Addresses		Authors' Addresses
	Dave Katz		Dave Katz
	Juniper Networks		Juniper Networks
	1194 N. Mathilda Ave.		1194 N. Mathilda Ave.
	Sunnyvale, California 94089-1206		Sunnyvale, California 94089-1206
	USA		USA
	Email: dkatz@juniper.net		Email: dkatz@juniper.net
	skipping to change at page 18, line 4 ¶		skipping to change at page 18, line 26 ¶
	Email: dkatz@juniper.net		Email: dkatz@juniper.net
	Dave Ward		Dave Ward
	Cisco Systems		Cisco Systems
	170 West Tasman Dr.		170 West Tasman Dr.
	San Jose, California 95134		San Jose, California 95134
	USA		USA
	Email: wardd@cisco.com		Email: wardd@cisco.com
	Santosh Pallagatti (editor)		Santosh Pallagatti (editor)
	Individual contributor		Individual contributor
	Email: santosh.pallagatti@gmail.com		Email: santosh.pallagatti@gmail.com
			Greg Mirsky (editor)
			ZTE Corp.
			Email: gregimirsky@gmail.com
End of changes. 25 change blocks.
	38 lines changed or deleted		57 lines changed or added
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