draft-ietf-bier-bfd-06.txt		draft-ietf-bier-bfd-07.txt
	BIER WG Q. Xiong		BIER WG Q. Xiong
	Internet-Draft ZTE Corporation		Internet-Draft ZTE Corporation
	Intended status: Standards Track G. Mirsky		Intended status: Standards Track G. Mirsky
	Expires: 27 December 2024 Ericsson		Expires: 24 January 2025 Ericsson
	F. Hu		F. Hu
	Individual		Individual
	C. Liu		C. Liu
	China Unicom		China Unicom
	G. Mishra		G. Mishra
	Verizon Inc.		Verizon Inc.
	25 June 2024		23 July 2024
	BIER BFD		BIER BFD
	draft-ietf-bier-bfd-06		draft-ietf-bier-bfd-07
	Abstract		Abstract
	Point to multipoint (P2MP) BFD is designed to verify multipoint		Point to multipoint (P2MP) BFD is designed to verify multipoint
	connectivity. This document specifies the application of P2MP BFD in		connectivity. This document specifies the application of P2MP BFD in
	BIER network.		BIER network.
	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 39 ¶		skipping to change at page 1, line 39 ¶
	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 27 December 2024.		This Internet-Draft will expire on 24 January 2025.
	Copyright Notice		Copyright Notice
	Copyright (c) 2024 IETF Trust and the persons identified as the		Copyright (c) 2024 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 26 ¶		skipping to change at page 2, line 26 ¶
	4. BIER BFD Session Bootstrapping . . . . . . . . . . . . . . . 3		4. BIER BFD Session Bootstrapping . . . . . . . . . . . . . . . 3
	4.1. BIER OAM Bootstrapping . . . . . . . . . . . . . . . . . 4		4.1. BIER OAM Bootstrapping . . . . . . . . . . . . . . . . . 4
	4.2. IGP Bootstrapping . . . . . . . . . . . . . . . . . . . . 4		4.2. IGP Bootstrapping . . . . . . . . . . . . . . . . . . . . 4
	4.2.1. IS-IS Extension for BIER BFD . . . . . . . . . . . . 5		4.2.1. IS-IS Extension for BIER BFD . . . . . . . . . . . . 5
	4.2.2. OSPF Extension for BIER BFD . . . . . . . . . . . . . 6		4.2.2. OSPF Extension for BIER BFD . . . . . . . . . . . . . 6
	4.3. BGP Bootstrapping . . . . . . . . . . . . . . . . . . . . 7		4.3. BGP Bootstrapping . . . . . . . . . . . . . . . . . . . . 7
	5. Discriminators and Packet Demultiplexing . . . . . . . . . . 7		5. Discriminators and Packet Demultiplexing . . . . . . . . . . 7
	6. Active Tail in BIER BFD . . . . . . . . . . . . . . . . . . . 7		6. Active Tail in BIER BFD . . . . . . . . . . . . . . . . . . . 7
	6.1. Unsolicited Head Notification Mode . . . . . . . . . . . 7		6.1. Unsolicited Head Notification Mode . . . . . . . . . . . 7
	7. Security Considerations . . . . . . . . . . . . . . . . . . . 8		7. Security Considerations . . . . . . . . . . . . . . . . . . . 8
	8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8		8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9
	9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9		9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
	9.1. BIER OAM Message Type . . . . . . . . . . . . . . . . . . 9		9.1. BIER OAM Message Type . . . . . . . . . . . . . . . . . . 9
	9.2. BFD Discriminator TLV . . . . . . . . . . . . . . . . . . 9		9.2. BFD Discriminator TLV . . . . . . . . . . . . . . . . . . 9
	9.3. BIER BFD Sub-sub-TLV . . . . . . . . . . . . . . . . . . 9		9.3. BIER BFD Sub-sub-TLV . . . . . . . . . . . . . . . . . . 9
	9.4. BIER BFD Sub-TLV . . . . . . . . . . . . . . . . . . . . 9		9.4. BIER BFD Sub-TLV . . . . . . . . . . . . . . . . . . . . 10
	9.5. BGP's BFD Discriminator Attribute Mode of P2MP Session with		9.5. BGP's BFD Discriminator Attribute Mode of P2MP Session with
	Active Tails . . . . . . . . . . . . . . . . . . . . . . 10		Active Tails . . . . . . . . . . . . . . . . . . . . . . 10
	10. References . . . . . . . . . . . . . . . . . . . . . . . . . 10		10. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
	10.1. Normative References . . . . . . . . . . . . . . . . . . 10		10.1. Normative References . . . . . . . . . . . . . . . . . . 10
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
	1. Introduction		1. Introduction
	Bit Index Explicit Replication (BIER) [RFC8279] provides the		Bit Index Explicit Replication (BIER) [RFC8279] provides the
	forwarding of multicast data packets through a multicast domain. It		forwarding of multicast data packets through a multicast domain. It
	does so without requiring any explicit tree-building protocol and		does so without requiring any explicit tree-building protocol and
	without requiring intermediate nodes to maintain any per-flow state.		without requiring intermediate nodes to maintain any per-flow state.
	[RFC8562] defines a method of using Bidirectional Forwarding		[RFC8562] defines a method of using Bidirectional Forwarding
	Detection (BFD) to monitor and detect unicast failures between the		Detection (BFD) to monitor and detect failures between the sender
	sender (head) and one or more receivers (tails) in multipoint or		(head) and one or more receivers (tails) in multipoint or multicast
	multicast networks. [RFC8563] describes active tail extensions to		networks. [RFC8563] describes active tail extensions to the BFD
	the BFD protocol for multipoint networks.		protocol for multipoint networks.
	This document describes the procedures for using such mode of BFD		This document describes the procedures for using such mode of BFD
	protocol to monitor connectivity between a multipoint sender, Bit-		protocol to monitor connectivity between a multipoint sender, Bit-
	Forwarding Ingress Router (BFIR), and a set of one or more multipoint		Forwarding Ingress Router (BFIR), and a set of one or more multipoint
	receivers, Bit-Forwarding Egress Routers (BFERs). The BIER BFD only		receivers, Bit-Forwarding Egress Routers (BFERs). The BIER BFD only
	supports the unidirectional multicast. This document defines the use		supports the unidirectional multicast. This document defines the use
	of P2MP BFD as per [RFC8562], and active tail as per [RFC8563] for		of P2MP BFD as per [RFC8562], and active tail as per [RFC8563] for
	BIER-specific domain.		BIER-specific domain.
	2. Conventions used in this document		2. Conventions used in this document
	skipping to change at page 3, line 48 ¶		skipping to change at page 3, line 48 ¶
	set to BIER BFD (TBD1 will be assigned by IANA Section 9.1). BFD		set to BIER BFD (TBD1 will be assigned by IANA Section 9.1). BFD
	Control packet, defined in Section 4 [RFC5880], immediately follows		Control packet, defined in Section 4 [RFC5880], immediately follows
	the BIER OAM header. The operation of Multipoint BFD with the BFD		the BIER OAM header. The operation of Multipoint BFD with the BFD
	Control Packet is described in [RFC8562].		Control Packet is described in [RFC8562].
	4. BIER BFD Session Bootstrapping		4. BIER BFD Session Bootstrapping
	As defined in [RFC8562], a BIER BFD session MAY be established to		As defined in [RFC8562], a BIER BFD session MAY be established to
	monitor the state of the multipoint path. The BIER BFD session could		monitor the state of the multipoint path. The BIER BFD session could
	be created for each multipoint path and the set of BFERs over which		be created for each multipoint path and the set of BFERs over which
	the BFIR is requested to run BIER BFD. The BFIR MUST advertise the		the BFIR is requested to run BIER BFD. The BFIR, according to
	multipoint path and the value of My Discriminator associated with the		Section 5.7 of [RFC8562], MAY bootstrap the BFD session using a BIER
	path to the set of BFERs. The BFIR MUST bootstrap the BFD session		OAM message (Section 4.1) or the control plane (Section 4.2,
	and advertise the BFD information to the set of BFERs. Bootstrapping		Section 4.3). Either method MUST refer to the multipoint path and
	a BIER BFD session MAY use BIER OAM message (Section 4.1) or the		the value of My Discriminator associated with the path to the set of
	control plane (Section 4.2, Section 4.3).		BFERs. The BIER BFD bootstrapping MUST be repeated when the value of
			My Discriminator is changed.
	The BIER BFD bootstrapping MUST be repeated when the value of this
	discriminator being changed.
	4.1. BIER OAM Bootstrapping		4.1. BIER OAM Bootstrapping
	The BIER OAM could be used for bootstrapping the BIER BFD session.		The BIER OAM could be used for bootstrapping the BIER BFD session.
	The BFIR sends the BIER OAM Echo request message carrying a BFD		The BFIR sends the BIER OAM Echo request message carrying a BFD
	discriminator TLV which immediately follows the Target SI-Bitstring		discriminator TLV which immediately follows the Target SI-Bitstring
	TLV (section 3.3.2 [I-D.ietf-bier-ping]).		TLV (section 3.3.2 [I-D.ietf-bier-ping]).
	The Target SI-Bitstring TLV MUST be used to carry the set of BFER		The Target SI-Bitstring TLV MUST be used to carry the set of BFER
	information (including Sub-domain-id, Set ID, BS Len, Bitstring) for		information (including Sub-domain-id, Set ID, BS Len, Bitstring) for
	skipping to change at page 4, line 41 ¶		skipping to change at page 4, line 39 ¶
	where:		where:
	* Type indicates BFD Discriminator TLV. The value (TBD2) is to be		* Type indicates BFD Discriminator TLV. The value (TBD2) is to be
	allocated by IANA (Section 9.2).		allocated by IANA (Section 9.2).
	* Length MUST be set to 4.		* Length MUST be set to 4.
	* My Discriminator - four-octet long field. The value is the local		* My Discriminator - four-octet long field. The value is the local
	discriminator generated by BFIR for this session. This		discriminator generated by BFIR for this session. This
	discriminator MUST be used as the My Discriminator field n the		discriminator MUST be used as the My Discriminator field in the
	BIER BFD Control packets sent by the BFIR.		BIER BFD Control packets sent by the BFIR.
	4.2. IGP Bootstrapping		4.2. IGP Bootstrapping
	An alternative option to bootstrap the BIER BFD using a BIER OAM		An alternative option to bootstrap the BIER BFD using a BIER OAM
	message is to advertise the BFD information by an IGP protocol over		message is to advertise the BFD information by an IGP protocol over
	the control plane. This document defines a new BIER BFD Sub-sub-TLV		the control plane. This document defines a new BIER BFD Sub-sub-TLV
	to carry BFD information in IGP protocols IS-IS and OSPF.		to carry BFD information in IGP protocols IS-IS and OSPF.
	The BFIR generates the My Discriminator value for each multicast flow		The BFIR generates the My Discriminator value for each multicast flow
	skipping to change at page 5, line 45 ¶		skipping to change at page 5, line 45 ¶
	* Type indicates BIER BFD sub-sub-TLV. The value (TBD3) is to be		* Type indicates BIER BFD sub-sub-TLV. The value (TBD3) is to be
	allocated by IANA (Section 9.3).		allocated by IANA (Section 9.3).
	* Length is a two-octet field. The value is the length of the BIER		* Length is a two-octet field. The value is the length of the BIER
	BFD Sub-sub-TLV for IS-IS extension, in octets		BFD Sub-sub-TLV for IS-IS extension, in octets
	* My Discriminator is a four-octet long field. The value is a		* My Discriminator is a four-octet long field. The value is a
	unique, nonzero discriminator value generated by BFIR for each		unique, nonzero discriminator value generated by BFIR for each
	multipoint path. This discriminator MUST be used as the My		multipoint path. This discriminator MUST be used as the My
	Discriminator field n the BIER BFD Control packets sent by the		Discriminator field in the BIER BFD Control packets sent by the
	BFIR.		BFIR.
	* BIFT-id is a two-octet field. The value represents a particular		* BIFT-id is a two-octet field. The value represents a particular
	Bit Index Forwarding Table (BIFT) as per [RFC8279].		Bit Index Forwarding Table (BIFT) as per [RFC8279].
	* BitString field carries the set of BFR-IDs of BFER(s) that the		* BitString field carries the set of BFR-IDs of BFER(s) that the
	BFIR expects to establish the BIER BFD session.		BFIR expects to establish the BIER BFD session.
	4.2.2. OSPF Extension for BIER BFD		4.2.2. OSPF Extension for BIER BFD
	skipping to change at page 6, line 42 ¶		skipping to change at page 6, line 42 ¶
	* Type indicates BIER BFD sub-TLV. The value (TBD4) is to be		* Type indicates BIER BFD sub-TLV. The value (TBD4) is to be
	allocated by IANA (Section 9.4).		allocated by IANA (Section 9.4).
	* Length is a two-octet field. The value is the length of the BIER		* Length is a two-octet field. The value is the length of the BIER
	BFD sub-TLV for OSPF extension, in octets		BFD sub-TLV for OSPF extension, in octets
	* My Discriminator is a four-octet long field. The value is a		* My Discriminator is a four-octet long field. The value is a
	unique, nonzero discriminator value generated by BFIR for each		unique, nonzero discriminator value generated by BFIR for each
	multipoint path. This discriminator MUST be used as the My		multipoint path. This discriminator MUST be used as the My
	Discriminator field n the BIER BFD Control packets sent by the		Discriminator field in the BIER BFD Control packets sent by the
	BFIR.		BFIR.
	* BIFT-id is a two-octet field. The value represents a particular		* BIFT-id is a two-octet field. The value represents a particular
	Bit Index Forwarding Table (BIFT) as per [RFC8279].		Bit Index Forwarding Table (BIFT) as per [RFC8279].
	* BitString field carries the set of BFR-IDs of BFER(s) that the		* BitString field carries the set of BFR-IDs of BFER(s) that the
	BFIR expects to establish the BIER BFD session.		BFIR expects to establish the BIER BFD session.
	4.3. BGP Bootstrapping		4.3. BGP Bootstrapping
	skipping to change at page 8, line 28 ¶		skipping to change at page 8, line 28 ¶
	* BFD Control packet is encapsulated in IP/UDP with the destination		* BFD Control packet is encapsulated in IP/UDP with the destination
	IP address of the BFIR and the UDP destination port number set to		IP address of the BFIR and the UDP destination port number set to
	4784 per [RFC5883]		4784 per [RFC5883]
	* the BFD Control packets are transmitted at the rate of one per		* the BFD Control packets are transmitted at the rate of one per
	second until either the BFER receives valid for this BFD session		second until either the BFER receives valid for this BFD session
	control packet with the Final (F) bit is set from the BFIR or the		control packet with the Final (F) bit is set from the BFIR or the
	defect condition clears.		defect condition clears.
	To improve the likelihood of notifying the BFIR of the failure, the		To improve the likelihood of notifying the BFIR of the failure, the
	BFER SHOULD transmit three BFD Control packets defined above in short		BFER SHOULD transmit three BFD Control packets defined above in with
	succession.		pseudo-random intervals between packets within a one-second interval.
	A BFIR that has received the BFD Control packet, as described above,		A BFIR that has received the BFD Control packet, as described above,
	sends the unicast IP/UDP encapsulated BFD control packet with the		sends the unicast IP/UDP encapsulated BFD control packet with the
	Final (F) bit set to the BFER.		Final (F) bit set to the BFER.
	7. Security Considerations		7. Security Considerations
	For BIER OAM packet processing security considerations, see		For BIER OAM packet processing security considerations, see
	[I-D.ietf-bier-ping].		[I-D.ietf-bier-ping].
	For general multipoint BFD security considerations, see [RFC8562].		For general multipoint BFD security considerations, see [RFC8562].
	No additional security issues are raised in this document beyond		A single failure could affect a significant number of BFERs, thus
	those that exist in the referenced BFD documents.		causing a spike in the number of BFD Control packets with
			notifications, as defined in Section 6.1. To mitigate the
			overloading of the control plane, an implementation MUST control the
			number of BFD Control packets passed to the control plane for
			processing.
	8. Acknowledgements		8. Acknowledgements
	The authors would like to thank the comments and suggestions from		The authors would like to thank the comments and suggestions from
	Sandy Zhang, Jeffrey (Zhaohui) Zhang, Donald Eastlake 3rd.		Sandy Zhang, Jeffrey (Zhaohui) Zhang, Donald Eastlake 3rd, and Reshad
			Rahman.
	9. IANA Considerations		9. IANA Considerations
	9.1. BIER OAM Message Type		9.1. BIER OAM Message Type
	IANA is requested to assign a new type from the BIER OAM Message Type		IANA is requested to assign a new type from the BIER OAM Message Type
	registry as follows:		registry as follows:
	+=======+=============+=================+		+=======+=============+=================+
	| Value | Description | Reference |		| Value | Description | Reference |
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