< draft-mtm-rtgwg-bfd-mc-lag-00.txt		draft-mtm-rtgwg-bfd-mc-lag-01.txt >
	RTG Working Group G. Mirsky		RTG Working Group G. Mirsky
	Internet-Draft ZTE Corp.		Internet-Draft ZTE Corp.
	Intended status: Standards Track J. Tantsura		Intended status: Standards Track J. Tantsura
	Expires: May 1, 2021 Apstra		Expires: May 22, 2021 Apstra
	G. Mishra		G. Mishra
	Verizon Inc.		Verizon Inc.
	October 28, 2020		November 18, 2020
	Bidirectional Forwarding Detection (BFD) on Multi-chassis Link		Bidirectional Forwarding Detection (BFD) on Multi-chassis Link
	Aggregation Group (MC-LAG) Interfaces		Aggregation Group (MC-LAG) Interfaces
	draft-mtm-rtgwg-bfd-mc-lag-00		draft-mtm-rtgwg-bfd-mc-lag-01
	Abstract		Abstract
	This document describes the use of Bidirectional Forwarding Detection		This document describes the use of Bidirectional Forwarding Detection
	for Multi-chassis Link Aggregation Group to provide faster than Link		for Multi-chassis Link Aggregation Group to provide faster than Link
	Aggregation Control Protocol convergence. This specification		Aggregation Control Protocol convergence. This specification
	enhances RFC 7130 "Bidirectional Forwarding Detection (BFD) on Link		enhances RFC 7130 "Bidirectional Forwarding Detection (BFD) on Link
	Aggregation Group (LAG) Interfaces".		Aggregation Group (LAG) Interfaces".
	Status of This Memo		Status of This Memo
	skipping to change at page 1, line 38 ¶		skipping to change at page 1, line 38 ¶
	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 May 1, 2021.		This Internet-Draft will expire on May 22, 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 17 ¶		skipping to change at page 2, line 17 ¶
	described in the Simplified BSD License.		described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
	1.1. Conventions used in this document . . . . . . . . . . . . 2		1.1. Conventions used in this document . . . . . . . . . . . . 2
	1.1.1. Acronyms . . . . . . . . . . . . . . . . . . . . . . 2		1.1.1. Acronyms . . . . . . . . . . . . . . . . . . . . . . 2
	1.1.2. Requirements Language . . . . . . . . . . . . . . . . 3		1.1.2. Requirements Language . . . . . . . . . . . . . . . . 3
	2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3		2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3
	3. BFD on MC-LAG with IP-only Data Plane . . . . . . . . . . . . 3		3. BFD on MC-LAG with IP-only Data Plane . . . . . . . . . . . . 3
	4. BFD on MC-LAG with IP/MPLS Data Plane . . . . . . . . . . . . 4		4. BFD on MC-LAG with IP/MPLS Data Plane . . . . . . . . . . . . 3
	5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5		5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
	6. Security Considerations . . . . . . . . . . . . . . . . . . . 5		6. Security Considerations . . . . . . . . . . . . . . . . . . . 4
	7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5		7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
	8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5		8. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
	8.1. Normative References . . . . . . . . . . . . . . . . . . 5		8.1. Normative References . . . . . . . . . . . . . . . . . . 4
	8.2. Informative . . . . . . . . . . . . . . . . . . . . . . . 6		8.2. Informative . . . . . . . . . . . . . . . . . . . . . . . 5
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
	1. Introduction		1. Introduction
	The [RFC7130] defines the use of Bidirectional Forwarding Detection		The [RFC7130] defines the use of Bidirectional Forwarding Detection
	(BFD) on Link Aggregation Group (LAG) interfaces. A multi-chassis		(BFD) on Link Aggregation Group (LAG) interfaces. A multi-chassis
	LAG (MC-LAG) is a type of LAG [IEEE.802.1AX.2008] with member links		LAG (MC-LAG) is a type of LAG [IEEE.802.1AX.2008] with member links
	terminated on separate chassis. [IEEE.802.1AX.2008] does not specify		terminated on separate chassis. [IEEE.802.1AX.2008] does not specify
	MC-LAG but doesn't preclude it either. Link Aggregation Control		MC-LAG but doesn't preclude it either. Link Aggregation Control
	Protocol (LACP), also defined in [IEEE.802.1AX.2008], can work with		Protocol (LACP), also defined in [IEEE.802.1AX.2008], can work with
	MC-LAG but, as in the LAG case, the fastest link failure detection		MC-LAG but, as in the LAG case, the fastest link failure detection
	interval is only in a range of single-digit seconds. This document		interval is only in a range of single-digit seconds. This document
	defines how the mechanism defined to work on LAG interfaces [RFC7130]		defines how the mechanism defined to work on LAG interfaces [RFC7130]
	can be adapted to the MC-LAG case to enable sub-second detection of		can be adapted to the MC-LAG case to enable sub-second detection of
	member link failure.		member link failure.
	1.1. Conventions used in this document		1.1. Conventions used in this document
	1.1.1. Acronyms		1.1.1. Acronyms
	ACH: Associated Channel Header
	BFD: Bidirectional Forwarding Detection		BFD: Bidirectional Forwarding Detection
	BoS: Bottom of the Stack
	G-ACh: Generic Associated Channel
	GAL: Generic Associated Label
	LAG: Link Aggregation Group		LAG: Link Aggregation Group
	LACP: Link Aggregation Control Protocol		LACP: Link Aggregation Control Protocol
	MC-LAG: Multi-chassis Link Aggregation Group		MC-LAG: Multi-chassis Link Aggregation Group
	MPLS: Multi-Protocol Label Switching		MPLS: Multi-Protocol Label Switching
	1.1.2. Requirements Language		1.1.2. 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", "NOT RECOMMENDED", "MAY", and		"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
	"OPTIONAL" in this document are to be interpreted as described in BCP		"OPTIONAL" in this document are to be interpreted as described in BCP
	14 [RFC2119] [RFC8174] when, and only when, they appear in all		14 [RFC2119] [RFC8174] when, and only when, they appear in all
	capitals, as shown here.		capitals, as shown here.
	skipping to change at page 3, line 34 ¶		skipping to change at page 3, line 26 ¶
	[RFC7130] does not specify the selection of the destination IP		[RFC7130] does not specify the selection of the destination IP
	address for the BFD control packet. The only requirement related to		address for the BFD control packet. The only requirement related to
	the selection is in Section 2.1, stating that the use of the address		the selection is in Section 2.1, stating that the use of the address
	family across all member links of the given LAG MUST be consistent		family across all member links of the given LAG MUST be consistent
	across all the links. Thus it is implied that the same unicast IP		across all the links. Thus it is implied that the same unicast IP
	address will be used on all member links of the LAG as the use of		address will be used on all member links of the LAG as the use of
	different destination addresses would defeat the purpose of [RFC7130]		different destination addresses would defeat the purpose of [RFC7130]
	transforming the case into a set of single-hop BFD sessions		transforming the case into a set of single-hop BFD sessions
	[RFC5881]. But a single unicast IP address may not work in the MC-		[RFC5881]. But a single unicast IP address may not work in the MC-
	LAG case as the member links are terminated on the separate chassis.		LAG case as the member links are terminated on the separate chassis.
	This document proposes how to overcome this problem if using IP or		This document proposes overcoming this problem if using IP or Multi-
	Multi-Protocol Label Switching (MPLS) data plane encapsulation.		Protocol Label Switching (MPLS) data plane encapsulation.
	3. BFD on MC-LAG with IP-only Data Plane		3. BFD on MC-LAG with IP-only Data Plane
	As described in [RFC7130], a micro-BFD session on the LAG interfaces		As described in [RFC7130], a micro-BFD session on the LAG interfaces
	may use IPv4 or IPv6 address family. In some cases, two sessions,		may use IPv4 or IPv6 address family. In some cases, two sessions,
	one with IPv4 and one with IPv6 addresses, may run concurrently.		one with IPv4 and one with IPv6 addresses, may run concurrently.
	This document doesn't change any of these but specifies the selection		This document doesn't change any of these but specifies the selection
	of the destination IP address in the MC-LAG use case:		of the destination IP address in the MC-LAG use case:
	o if IPv4 address family is used for the micro-BFD session, then an		o if IPv4 address family is used for the micro-BFD session, then an
	skipping to change at page 4, line 11 ¶		skipping to change at page 3, line 49 ¶
	SHOULD be used as the destination IP address. The subnet		SHOULD be used as the destination IP address. The subnet
	broadcast address MAY be used as the destination IP address as		broadcast address MAY be used as the destination IP address as
	well;		well;
	o if the address family used is IPv6, then the IPv6 All Routers		o if the address family used is IPv6, then the IPv6 All Routers
	address with the link scope, as defined in [RFC4291], FF02::2/128		address with the link scope, as defined in [RFC4291], FF02::2/128
	MUST be used as the destination IP address.		MUST be used as the destination IP address.
	4. BFD on MC-LAG with IP/MPLS Data Plane		4. BFD on MC-LAG with IP/MPLS Data Plane
	There are more optional encapsulation formats for the case of micro-		IP/UDP is the most natural encapsulation format for the case of
	BFD on MC-LAG over IP/MPLS data plane:		micro-BFD on MC-LAG over IP/MPLS data plane as displayed in Figure 1.
	o [RFC5586] defined the special-purpose Generic Associated channel
	Label (GAL) that MAY be used in MPLS encapsulation of the micro-
	BFD control packet over the MPSL data plane. Depending on the
	channel type specified in the Associated Channel Header (ACH) that
	immediately follows after the GAL, micro-BFD MAY use IP/UDP, as
	displayed in Figure 1 or BFD format, i.e., BFD control packet
	without IP and UDP headers.
	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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| GAL | TC |1| TTL |		~ MPLS Label Stack ~
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-------
	|0 0 0 1|0 0 0 0| Reserved | IPv4 channel (0x0021) |		~ ~ |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ IP
	| |		| Destination IP address |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Header
	| |		| Source IP address | |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+------
	| Destination IP address |		| UDP header |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		| |
	| Source IP address |		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		~ BFD Control Packet ~
	| UDP header |		| |
	| |		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	~ BFD Control Packet ~
	| |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Figure 1: BFD on MC-LAG member link on IPv4/MPLS data plane		Figure 1: BFD on MC-LAG member link on IPv4/MPLS data plane
	If the IP/UDP format of BFD over MC-LAG interfaces is used, then the		An IP and UDP headers immediately follow an MPLS label stack. The
	destination IP address MUST be set to the loopback address		destination IP address MUST be set to the loopback address
	127.0.0.1/32 for IPv4 [RFC1812], or the loopback address ::1/128 for		127.0.0.1/32 for IPv4 [RFC1812], or the loopback address ::1/128 for
	IPv6 [RFC4291].		IPv6 [RFC4291]. TTL or Hop Limit field value MUST be set to 255,
			according to [RFC5881].
	5. IANA Considerations		5. IANA Considerations
	This document makes no requests for IANA allocations. This section		This document makes no requests for IANA allocations. This section
	may be deleted by RFC Editor.		may be deleted by RFC Editor.
	6. Security Considerations		6. Security Considerations
	This document does not introduce new security concerns but inherits		This document does not introduce new security concerns but inherits
	all security considerations discussed in [RFC5881] and [RFC7130].		all security considerations discussed in [RFC5881] and [RFC7130].
	skipping to change at page 5, line 32 ¶		skipping to change at page 5, line 10 ¶
	[IEEE.802.1AX.2008]		[IEEE.802.1AX.2008]
	"IEEE Standard for Local and metropolitan area networks -		"IEEE Standard for Local and metropolitan area networks -
	Link Aggregation", IEEE 802.1-AX, November 2008.		Link Aggregation", IEEE 802.1-AX, November 2008.
	[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>.
	[RFC5586] Bocci, M., Ed., Vigoureux, M., Ed., and S. Bryant, Ed.,
	"MPLS Generic Associated Channel", RFC 5586,
	DOI 10.17487/RFC5586, June 2009,
	<https://www.rfc-editor.org/info/rfc5586>.
	[RFC5881] Katz, D. and D. Ward, "Bidirectional Forwarding Detection		[RFC5881] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
	(BFD) for IPv4 and IPv6 (Single Hop)", RFC 5881,		(BFD) for IPv4 and IPv6 (Single Hop)", RFC 5881,
	DOI 10.17487/RFC5881, June 2010,		DOI 10.17487/RFC5881, June 2010,
	<https://www.rfc-editor.org/info/rfc5881>.		<https://www.rfc-editor.org/info/rfc5881>.
	[RFC7130] Bhatia, M., Ed., Chen, M., Ed., Boutros, S., Ed.,		[RFC7130] Bhatia, M., Ed., Chen, M., Ed., Boutros, S., Ed.,
	Binderberger, M., Ed., and J. Haas, Ed., "Bidirectional		Binderberger, M., Ed., and J. Haas, Ed., "Bidirectional
	Forwarding Detection (BFD) on Link Aggregation Group (LAG)		Forwarding Detection (BFD) on Link Aggregation Group (LAG)
	Interfaces", RFC 7130, DOI 10.17487/RFC7130, February		Interfaces", RFC 7130, DOI 10.17487/RFC7130, February
	2014, <https://www.rfc-editor.org/info/rfc7130>.		2014, <https://www.rfc-editor.org/info/rfc7130>.
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