< draft-ietf-bfd-stability-06.txt		draft-ietf-bfd-stability-07.txt >
	Network Working Group A. Mishra		Network Working Group A. Mishra
	Internet-Draft SES		Internet-Draft SES
	Intended status: Standards Track M. Jethanandani		Intended status: Standards Track M. Jethanandani
	Expires: January 14, 2021 Kloud Services		Expires: July 18, 2021 Kloud Services
	A. Saxena		A. Saxena
	Ciena Corporation		Ciena Corporation
	S. Pallagatti		S. Pallagatti
	VmWare		VmWare
	M. Chen		M. Chen
	Huawei		Huawei
	P. Fan		P. Fan
	China Mobile		China Mobile
	July 13, 2020		Jan 14, 2021
	BFD Stability		BFD Stability
	draft-ietf-bfd-stability-06		draft-ietf-bfd-stability-07
	Abstract		Abstract
	This document describes extensions to the Bidirectional Forwarding		This document describes extensions to the Bidirectional Forwarding
	Detection (BFD) protocol to measure BFD stability. Specifically, it		Detection (BFD) protocol to measure BFD stability. Specifically, it
	describes a mechanism for detection of BFD packet loss.		describes a mechanism for detection of BFD packet loss.
	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
	skipping to change at page 1, line 41 ¶		skipping to change at page 1, line 41 ¶
	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 January 14, 2021.		This Internet-Draft will expire on July 18, 2021.
	Copyright Notice		Copyright Notice
	Copyright (c) 2020 IETF Trust and the persons identified as the		Copyright (c) 2021 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
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	skipping to change at page 2, line 36 ¶		skipping to change at page 2, line 36 ¶
	1. Introduction		1. Introduction
	The Bidirectional Forwarding Detection ( BFD) [RFC5880] protocol		The Bidirectional Forwarding Detection ( BFD) [RFC5880] protocol
	operates by transmitting and receiving BFD control packets, generally		operates by transmitting and receiving BFD control packets, generally
	at high frequency, over the datapath being monitored. In order to		at high frequency, over the datapath being monitored. In order to
	prevent significant data loss due to a datapath failure, BFD session		prevent significant data loss due to a datapath failure, BFD session
	detection time as defined in BFD [RFC5880] is set to the smallest		detection time as defined in BFD [RFC5880] is set to the smallest
	feasible value.		feasible value.
	This document proposes a mechanism to detect lost packet in a BFD		This document proposes a mechanism to detect lost packets in a BFD
	session in addition to the datapath fault detection mechanisms of		session in addition to the datapath fault detection mechanisms of
	BFD. Such a mechanism presents significant value to measure the		BFD. Such a mechanism presents significant value to measure the
	stability of BFD sessions and provides data to the operators for the		stability of BFD sessions and provides data to the operators for the
	cause of a BFD failure.		cause of a BFD failure.
	This document does not propose any BFD extension to measure data		This document does not propose any BFD extension to measure data
	traffic loss or delay on a link or tunnel and the scope is limited to		traffic loss or delay on a link or tunnel and the scope is limited to
	BFD packets.		BFD packets.
	2. Terminology		2. Terminology
	skipping to change at page 3, line 13 ¶		skipping to change at page 3, line 13 ¶
	RFC 8174 [RFC8174].		RFC 8174 [RFC8174].
	The reader is expected to be familiar with the BFD [RFC5880],		The reader is expected to be familiar with the BFD [RFC5880],
	Optimizing BFD Authentication		Optimizing BFD Authentication
	[I-D.ietf-bfd-optimizing-authentication] and BFD Secure Sequence		[I-D.ietf-bfd-optimizing-authentication] and BFD Secure Sequence
	Numbers [I-D.ietf-bfd-secure-sequence-numbers].		Numbers [I-D.ietf-bfd-secure-sequence-numbers].
	3. Use Cases		3. Use Cases
	Bidirectional Forwarding Detection as defined in BFD [RFC5880] cannot		Bidirectional Forwarding Detection as defined in BFD [RFC5880] cannot
	detect any BFD packet loss if loss does not last for detection time.		detect any BFD packet loss if the loss does not last for detection
	This document proposes a method to detect a dropped packet on the		time. This document proposes a method to detect a dropped packet on
	receiver. For example, if the receiver receives BFD control packet k		the receiver. For example, if the receiver receives BFD control
	at time t but receives packet k+3 at time t+10ms, and never receives		packet k at time t but receives packet k+3 at time t+10ms, and never
	packet k+1 and/or k+2, then it has experienced a drop.		receives packet k+1 and/or k+2, then it has experienced a drop.
	This proposal enables BFD implementation to generate diagnostic		This proposal enables BFD implementations to generate diagnostic
	information on the health of each BFD session that could be used to		information on the health of each BFD session that could be used to
	preempt a failure on a link that BFD was monitoring by allowing time		preempt a failure on a datapath that BFD was monitoring by allowing
	for a corrective action to be taken.		time for a corrective action to be taken.
	In a faulty datapath scenario, an operator can use BFD health		In a faulty datapath scenario, an operator can use BFD health
	information to trigger delay and loss measurement OAM protocol		information to trigger delay and loss measurement OAM protocol
	(Connectivity Fault Management (CFM) or Loss Measurement (LM)-Delay		(Connectivity Fault Management (CFM) or Loss Measurement (LM)-Delay
	Measurement (DM)) to further isolate the issue.		Measurement (DM)) to further isolate the issue.
	4. BFD Null-Authentication Type		4. BFD Null-Authentication Type
	The functionality proposed for BFD stability measurement is achieved		The functionality proposed for BFD stability measurement is achieved
	by appending the Null-Authentication type (as defined in Optimizing		by appending an authentication section with the NULL Authentication
	BFD Authentication [I-D.ietf-bfd-optimizing-authentication] ) to the		type (as defined in Optimizing BFD Authentication
	BFD control packets that do not have authentication enabled.		[I-D.ietf-bfd-optimizing-authentication] ) to the BFD control packets
			that do not have authentication enabled.
	5. Theory of Operation		5. Theory of Operation
	This mechanism allows operators to measure the loss of BFD control		This mechanism allows operators to measure the loss of BFD control
	packets.		packets.
	When using MD5 or SHA authentication, BFD uses authentication TLV		When using MD5 or SHA authentication, BFD uses an authentication
	that carries the Sequence Number. However, if non-meticulous		section that carries the Sequence Number. However, if non-meticulous
	authentication is being used, or no authentication is in use, then		authentication is being used, or no authentication is in use, then
	the non-authenticated BFD packets MUST include NULL-Auth TLV.		the non-authenticated BFD control packets MUST include an
			authentication section with the NULL Authentication type.
	5.1. Loss Measurement		5.1. Loss Measurement
	Loss measurement counts the number of BFD control packets missed at		Loss measurement counts the number of BFD control packets missed at
	the receiver during any Detection Time period. The loss is detected		the receiver during any Detection Time period. The loss is detected
	by comparing the Sequence Number field in the Auth TLV (NULL or		by comparing the Sequence Number field in the Auth TLV (NULL or
	otherwise) in successive BFD control packets. The Sequence Number in		otherwise) in successive BFD control packets. The Sequence Number in
	each successive control packet generated on a BFD session by the		each successive control packet generated on a BFD session by the
	transmitter is incremented by one.		transmitter is incremented by one.
	The first BFD NULL-Auth type processed by the receiver that has a		The first BFD authentication section with a non-zero sequence number,
	non-zero sequence number is used for bootstrapping the logic. When		in a valid BFD control packet, processed by the receiver is used for
	using secure sequence numbers, if the expected values are pre-		bootstrapping the logic. When using secure sequence numbers, if the
	calculated, the value must be matched to detect lost packets as		expected values are pre-calculated, the value must be matched to
	defined in BFD secure sequence numbers		detect lost packets as defined in BFD secure sequence numbers
	[I-D.ietf-bfd-secure-sequence-numbers].		[I-D.ietf-bfd-secure-sequence-numbers].
	6. IANA Considerations		6. IANA Considerations
	This document has no actions for IANA.		This document has no actions for IANA.
	7. Security Consideration		7. Security Consideration
	Other than concerns raised in BFD [RFC5880], Optimizing BFD		Other than concerns raised in BFD [RFC5880], Optimizing BFD
	Authentication [I-D.ietf-bfd-optimizing-authentication] and BFD		Authentication [I-D.ietf-bfd-optimizing-authentication] and BFD
	skipping to change at page 4, line 40 ¶		skipping to change at page 4, line 41 ¶
	Authors would like to thank Nobo Akiya, Jeffery Haas, Peng Fan,		Authors would like to thank Nobo Akiya, Jeffery Haas, Peng Fan,
	Dileep Singh, Basil Saji, Sagar Soni and Mallik Mudigonda who also		Dileep Singh, Basil Saji, Sagar Soni and Mallik Mudigonda who also
	contributed to this document.		contributed to this document.
	10. Normative References		10. Normative References
	[I-D.ietf-bfd-optimizing-authentication]		[I-D.ietf-bfd-optimizing-authentication]
	Jethanandani, M., Mishra, A., Saxena, A., and M. Bhatia,		Jethanandani, M., Mishra, A., Saxena, A., and M. Bhatia,
	"Optimizing BFD Authentication", draft-ietf-bfd-		"Optimizing BFD Authentication", draft-ietf-bfd-
	optimizing-authentication-09 (work in progress), December		optimizing-authentication-11 (work in progress), July
	2019.		2020.
	[I-D.ietf-bfd-secure-sequence-numbers]		[I-D.ietf-bfd-secure-sequence-numbers]
	Jethanandani, M., Agarwal, S., Mishra, A., Saxena, A., and		Jethanandani, M., Agarwal, S., Mishra, A., Saxena, A., and
	A. DeKok, "Secure BFD Sequence Numbers", draft-ietf-bfd-		A. DeKok, "Secure BFD Sequence Numbers", draft-ietf-bfd-
	secure-sequence-numbers-05 (work in progress), February		secure-sequence-numbers-07 (work in progress), December
	2020.		2020.
	[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>.
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