< draft-wang-bier-rh-bier-02.txt		draft-wang-bier-rh-bier-03.txt >
	BIER Working Group W. Wang		BIER Working Group W. Wang
	Internet-Draft A. Wang		Internet-Draft A. Wang
	Intended status: Standards Track China Telecom		Intended status: Standards Track China Telecom
	Expires: April 28, 2022 October 25, 2021		Expires: July 2, 2022 December 29, 2021
	Routing Header Based BIER Information Encapsulation		Routing Header Based BIER Information Encapsulation
	draft-wang-bier-rh-bier-02		draft-wang-bier-rh-bier-03
	Abstract		Abstract
	This draft proposes one new encapsulation schema of Bit Index		This draft proposes one new encapsulation schema of Bit Index
	Explicit Replication (BIER) information to transfer the multicast		Explicit Replication (BIER) information to transfer the multicast
	packets within the IPv6 network. By using a new IPv6 Routing Header		packets within the IPv6 network. By using a new type of IPv6 Routing
	type to forward the packet, the original source address and		Header to forward the packet, the original source address and
	destination address of the multicast packet is kept unchanged along		destination address of the multicast packet is kept unchanged along
	the forwarding path. Such encapsulation schema can make full use of		the forwarding path. Such encapsulation schema can make full use of
	the existing IPv6 quality assurance solutions to provide high-quality		the existing IPv6 quality assurance solutions to provide high-quality
	multicast service.		multicast service.
	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 April 28, 2022.		This Internet-Draft will expire on July 2, 2022.
	Copyright Notice		Copyright Notice
	Copyright (c) 2021 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
	skipping to change at page 2, line 14 ¶		skipping to change at page 2, line 14 ¶
	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
	described in the Simplified BSD License.		described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
	2. Conventions used in this document . . . . . . . . . . . . . . 3		2. Conventions used in this document . . . . . . . . . . . . . . 3
	3. BIER Routing Header . . . . . . . . . . . . . . . . . . . . . 3		3. BIER Routing Header . . . . . . . . . . . . . . . . . . . . . 3
	4. Multicast Packet Forwarding Procedures . . . . . . . . . . . 5		4. Multicast Packet Forwarding Procedures . . . . . . . . . . . 5
	4.1. All devices in BIER domain support BIER Routing Header . 5		4.1. All nodes in BIER domain support BIER Routing Header . . 6
	4.2. Some devices in BIER domain do not support BIER Routing		4.2. Some nodes in BIER domain do not support BIER Routing
	Header . . . . . . . . . . . . . . . . . . . . . . . . . 7		Header . . . . . . . . . . . . . . . . . . . . . . . . . 7
	5. Security Considerations . . . . . . . . . . . . . . . . . . . 8		5. Security Considerations . . . . . . . . . . . . . . . . . . . 9
	6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8		6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
	7. References . . . . . . . . . . . . . . . . . . . . . . . . . 9		7. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
	7.1. Normative References . . . . . . . . . . . . . . . . . . 9		7.1. Normative References . . . . . . . . . . . . . . . . . . 9
	7.2. Informative References . . . . . . . . . . . . . . . . . 9		7.2. Informative References . . . . . . . . . . . . . . . . . 10
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
	1. Introduction		1. Introduction
	Bit Index Explicit Replication (BIER) is a new multicast technology		Bit Index Explicit Replication (BIER) is a new multicast technology
	based on IPv6 defined in [RFC8279]. In BIER domain, the set of		based on IPv6 defined in [RFC8279]. In BIER domain, the set of
	destination nodes of multicast message is mapped into a BitString and		destination nodes of multicast message is mapped into a BitString and
	encapsulated into the BIER header. The position of each bit in the		encapsulated into the BIER header. The position of each bit in the
	BitString represents an BFER. Compared with the traditional		BitString represents an BFER. Compared with the traditional
	multicast technology, the nodes in BIER domain do not need to		multicast technologies, the nodes in BIER domain do not need to
	maintain a multicast tree and keep the multicast flow state for each		maintain a multicast tree and keep the multicast flow state for each
	multicast flow.		multicast flow.
	Currently, there are two methods for encapsulating BIER information		Currently, there are two methods for encapsulating BIER information
	based on IPv6 in IETF: BIERn6([I-D.ietf-bier-bierin6]) and		based on IPv6 in IETF: BIERin6([I-D.ietf-bier-bierin6]) and
	BIERv6([I-D.xie-bier-ipv6-encapsulation]).		BIERv6([I-D.xie-bier-ipv6-encapsulation]).
	BIERin6 carries BIER information by defining a new IPv6 next header		BIERin6 carries BIER information by defining a new IPv6 next header
	type. During the forwarding process, the source address and		type. During the forwarding process, the source address and
	destination address in the header will be changed.		destination address in the header will be changed.
	BIERv6 carries bier related information by defining an new option		BIERv6 carries bier related information by defining an new type of
	type of destination options header (i.e. bier option). The source		destination options header (i.e. bier option). The source address in
	address in the header remains unchanged but the destination address		the header remains unchanged but the destination address will be
	will be changed along the forwarding path.		changed along the forwarding path.
	The differences between the above two BIER encapsulation and		The differences between the above two BIER encapsulation and
	forwarding schemes are unfavorable for the development of BIER and		forwarding schemes are unfavorable for the development of BIER and
	its derivatives. In addition, when there is error in the forward		its derivatives. In addition, when there is error in the forward
	process of the multicast packet, the change of source address and		process of the multicast packet, the change of source address and
	destination address during transmission will increase the difficulty		destination address during transmission will increase the difficulty
	of fault location and traceability.		of fault location and traceability.
	This draft proposes a BIER information transmission scheme without		This draft proposes a BIER information transmission scheme without
	changing the multicast source and destination addresses. The		changing the multicast source and destination addresses. The
	skipping to change at page 3, line 31 ¶		skipping to change at page 3, line 31 ¶
	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", "MAY", and "OPTIONAL" in this
	document are to be interpreted as described in [RFC2119] .		document are to be interpreted as described in [RFC2119] .
	3. BIER Routing Header		3. BIER Routing Header
	One new type of IPv6 Routing Header is defined according to		One new type of IPv6 Routing Header is defined according to
	[RFC8200]. The message format is shown in Figure 1.		[RFC8200]. The message format is shown in Figure 1.
			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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Next Header | Hdr Ext Len | Routing Type | Segment Left |		| Next Header | Hdr Ext Len | Routing Type | Segment Left |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| BIFT-id | Ver | TTL |		| BIFT-id | TC |S| TTL |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| BSL | Entropy | DSCP |OAM|		|Nibble | Ver | BSL | Entropy |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| BFIR-id |Rsv| Reserved |		|OAM|Rsv| DSCP | Proto | BFIR-id |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| |		| BitString (first 32 bits) ~
	. .		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	. BitString .		~ ~
	. .		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| |		~ BitString (last 32 bits) |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Figure 1: The format of BIER Routing Header		Figure 1: The format of BIER Routing Header
	Where:		Where:
	o Next Header(8 bits): indicating the message header type		o Next Header(8 bits): indicating the message header type
	immediately after the routing header.		immediately after the routing header.
	o HDR Ext Len(8 bits): indicating the length of the routing header.		o HDR Ext Len(8 bits): indicating the length of the routing header.
	skipping to change at page 4, line 20 ¶		skipping to change at page 4, line 20 ¶
	o Routing Type(8 bits): TBD. Identifying the newly defined Routing		o Routing Type(8 bits): TBD. Identifying the newly defined Routing
	Header to encode BIER information.		Header to encode BIER information.
	o Segments Left(8 bits): indicating the number of explicitly listed		o Segments Left(8 bits): indicating the number of explicitly listed
	intermediate nodes to be accessed before reaching the final		intermediate nodes to be accessed before reaching the final
	destination. It is not used here for the time being, and all are		destination. It is not used here for the time being, and all are
	set to 0.		set to 0.
	o BIFT-id(20 bits): each < SD, Si, BSL > is assigned a BIFT-id.		o BIFT-id(20 bits): each < SD, Si, BSL > is assigned a BIFT-id.
	o Ver(4 bits): identifying the version of the BIER header. When an		o TC(3 bits): see [RFC8296]. This field is set to 0.
	unsupported BIER header version is received, the BFR needs to
	discard the packet and record the error.		o S(1 bit): see [RFC8296]. This field is set to 0.
	o TTL(8 bits): indicating the lifetime of the message. It is used		o TTL(8 bits): indicating the lifetime of the message. It is used
	to prevent ring. The processing process is the same as that in		to prevent ring. The processing process is the same as that in
	non MPLS networks.		non MPLS networks.
			o Nibble(4 bits): see [RFC8296]. This field is set to 0.
			o Ver(4 bits): identifying the version of the BIER header. When an
			unsupported BIER header version is received, the BFR needs to
			discard the packet and record the error.
	o BSL(4 bits): indicating the length of BitString.		o BSL(4 bits): indicating the length of BitString.
	o Entropy(20 bits): this field specifies an "entropy" for ECMP.		o Entropy(20 bits): this field specifies an "entropy" for ECMP.
	o DSCP(6 bits): this field is used to support different service
	codes.
	o OAM(2 bits): by default, this value will be set to 0 by BFIR, and		o OAM(2 bits): by default, this value will be set to 0 by BFIR, and
	other BFRs will not be modified. Whether to use this field is		other BFRs will not be modified. Whether to use this field is
	optional.		optional.
	o BFIR-id(16 bits): indicating BFR ID of BFIR.
	o Rsv(2 bits): unused, set to 0.		o Rsv(2 bits): unused, set to 0.
			o DSCP(6 bits): this field is used to support different service
			codes.
			o Proto(6 bits): see [RFC8296]. This field is set to 0.
			o BFIR-id(16 bits): indicating BFR ID of BFIR.
	o Reserved (14 bits): reserved field, set to 0.		o Reserved (14 bits): reserved field, set to 0.
	o BitString(variable): the length must be reflected in the BSL		o BitString(variable): the length must be reflected in the BSL
	field. The string saved in this field is used to identify the		field. The string saved in this field is used to identify the
	destination BFER of the packet.		destination BFER of the packet.
	4. Multicast Packet Forwarding Procedures		4. Multicast Packet Forwarding Procedures
	Based on the newly defined BIER Routing Header, the devices support		Based on the newly defined BIER Routing Header, the nodes support
	BIER Routing Header will perform the following steps to forward the		BIER Routing Header will perform the following steps to forward the
	multicast packets:		multicast packets:
	1) When BFIR receives the IPv6 multicast packets from the mulicast		1) When a BFIR receive a multicast packet, it will encapsulate a IPv6
	source, it will add BIER Routing Header to indicate the BFERs that		Header with BIER Routing Header. The payload is user data, the
	want to receives such multicast packet. The encapsulated multicast		source address is the IPv6 address of BFIR, and destination address
	packet will be forwarded according to the BIFT that identified by the		is the destination address of original multicast packet. BitString
	BIFT-id.		in BIER Routing Header indicates the BFERs that want to receives such
			multicast packet.
	2) Each BFR (includes BFIR) will check whether the direct-connected		2) BFIR checks whether there is BIFT corresponding to the BIFT-id
	device support BIER Routing Header. If yes, proceed to step 3);		locally. If not, it will discard the packet; otherwise, it will
	otherwise, proceed to step 2.1).		check whether the direct-connected node support BIER Routing Header.
			If the direct-connected node supports BIER Routing Header, proceeding
			to step 3). If the direct-connected node doesn't support BIER
			Routing Header, proceeding to step 2.1) .
	2.1) Calculating the IPv6 address of next hop that support BIER		2.1) BFIR Calculates the IPv6 address of next hop that support BIER
	Routing Header.		Routing Header.
	2.2) Encapsulating an outer IPv6 Header to the multicast packet. The		2.2) Encapsulating an outer IPv6 Header to the multicast packet. The
	calculated IPv6 address is used as the destination address of the		calculated IPv6 address is used as the destination address of the
	outer IPv6 Header, and its own IPv6 address is used as the source		outer IPv6 Header, and its own IPv6 address is used as the source
	address of the outer IPv6 Header. BitString will not be changed.		address of the outer IPv6 Header. BitString will not be changed.
	2.3) Sending the encapsulated packet to the direct-connected device,		2.3) Sending the encapsulated packet to the direct-connected node,
	the device will perform normal IPv6 forwarding according to the outer		the node will perform normal IPv6 forwarding according to the outer
	IPv6 Header.		IPv6 Header.
	3) On the router that supports the BIER Routing Header, perform the		3) Performing the normal BIER forwarding process as described in
	normal BIER forwarding process as described in [RFC8279].		[RFC8279].
			For a BFR, it performs the above procedures except 1).
	The detail procedures for forwarding the multicast packets based on		The detail procedures for forwarding the multicast packets based on
	the newly defined Routing Header are described in the following		the newly defined Routing Header are described in the following
	sections.		sections.
	4.1. All devices in BIER domain support BIER Routing Header		4.1. All nodes in BIER domain support BIER Routing Header
	+---+		+---+
	+-----------+ B +----------+		+-----------+ B +----------+
	| +---+ |		| +---+ |
	| 0:01000000 |		| 0:01000000 |
	| |		| |
	| |		| |
	| |		| |
	+-+-+ +-+-+ (Packet 2) +---+ (Packet 3)+---+		+-+-+ +-+-+ (Packet 2) +---+ (Packet 3)+---+
	| A |0:10000000 0:00100000| C +------------+ E +-----------+ F |		| A |0:10000000 0:00100000| C +------------+ E +-----------+ F |
	+-+-+ +-+-+ +---+ +---+		+-+-+ +-+-+ +---+ +---+
	| | 0:00001000 0:00000100		| | 0:00001000 0:00000100
	| |		| |
	| |		| |
	| |		| |
	| 0:00010000 |		| 0:00010000 |
	| +---+ |		| +---+ |
	+-----------+ D +----------+		+-----------+ D +----------+
	(Packet 1) +---+		(Packet 1) +---+
	Packet 1		Packet 1
	+------------------------------------+		+------------------------------------+
	IPv6 | IPv6 Address of Multicast Source |		IPv6 | IPv6 Address of A |
	Header +------------------------------------+		Header +------------------------------------+
	| IPv6 Multicast Destination Address |		with | IPv6 Multicast Destination Address |
	BIER +------------------------------------+		BIER +------------------------------------+
	Routing| BitString = 00101100 |		Routing| BIER RH(BitString = 00101100) |
	Header +------------------------------------+		Header +------------------------------------+
			| Original multicast packet |
			+------------------------------------+
	Packet 2		Packet 2
	+------------------------------------+		+------------------------------------+
	IPv6 | IPv6 Address of Multicast Source |		IPv6 | IPv6 Address of A |
	Header +------------------------------------+		Header +------------------------------------+
	| IPv6 Multicast Destination Address |		with | IPv6 Multicast Destination Address |
	BIER +------------------------------------+		BIER +------------------------------------+
	Routing| BitString = 00001100 |		Routing| BIER RH(BitString = 00001100) |
	Header +------------------------------------+		Header +------------------------------------+
			| Original multicast packet |
			+------------------------------------+
	Packet 3		Packet 3
	+------------------------------------+		+------------------------------------+
	IPv6 | IPv6 Address of Multicast Source |
	Header +------------------------------------+
	| IPv6 Multicast Destination Address |
	BIER +------------------------------------+
	Routing| BitString = 00000100 |
	Header +------------------------------------+
	Figure 2: All devices in BIER domain support BIER Routing Header		IPv6 | IPv6 Address of A |
			Header +------------------------------------+
			with | IPv6 Multicast Destination Address |
			BIER +------------------------------------+
			Routing| BIER RH(BitString = 00000100) |
			Header +------------------------------------+
			| Original multicast packet |
			+------------------------------------+
	The topology is shown in Figure 2, device A-F support BIER Routing		Figure 2: All nodes in BIER domain support BIER Routing Header
			The topology is shown in Figure 2, node A-F support BIER Routing
	Header. The packet need to be transmitted from A to F. The changes		Header. The packet need to be transmitted from A to F. The changes
	of the Routing Header have been given in Figure 2. Each device will		of the Routing Header have been given in Figure 2.
	perform the following steps after receiving the packet:
	1). Checking whether there is BIFT corresponding to the BIFT-id		1). Node A is BFIR, when it receives a multicast packet, it will
	locally. If yes, proceed to step 2); otherwise, discard the packet.		encapsulate a IPv6 Header with BIER Routing Header to the packet.
			The source address is the IPv6 address of itself, and the destination
			address is the destination address of original multicast packet.
	2). Checking whether the direct-connected device support BIER		2). Node A checks whether there is BIFT corresponding to the BIFT-id
	Routing Header. If yes, forwarding the packet according to the BIFT		locally. If not, discarding the packet; otherwise, forwarding the
	related to the BIFT-id; otherwise, see sectionSection 4.2 for detail		packet according to the BIFT related to the BIFT-id.
	procedures.
	During the forwarding procedures, the source address and destination		During the forwarding procedures, the source & destination address in
	address of the IPv6 multicast packet are not changed, only the		IPv6 header are not changed, only the BitString in BIER Routing
	BitString in BIER Routing Header is updated.		Header is updated.
	4.2. Some devices in BIER domain do not support BIER Routing Header		4.2. Some nodes in BIER domain do not support BIER Routing Header
	+---+		+---+
	+-----------+ B +-----------+		+-----------+ B +-----------+
	| +---+ |		| +---+ |
	| 0:01000000 |		| 0:01000000 |
	| |		| |
	| |		| |
	| |		| |
	+-+-+ +-+-+ +---+ (Packet 3) +---+		+-+-+ +-+-+ +---+ (Packet 3) +---+
	| A |0:10000000 | C +------------+ E +------------+ F |		| A |0:10000000 | C +------------+ E +------------+ F |
	+-+-+ +-+-+ +---+ +---+		+-+-+ +-+-+ +---+ +---+
	| | 0:00001000 0:00000100		| | 0:00001000 0:00000100
	| |		| |
	| |		| |
	| |		| |
	| 0:00010000 |		| 0:00010000 |
	| +---+ |		| +---+ |
	+-----------+ D +-----------+		+-----------+ D +-----------+
	(Packet 1) +---+(Packet 2)		(Packet 1) +---+ (Packet 2)
			Packet 1
			+------------------------------------+
			IPv6 | IPv6 Address of A |
			Header +------------------------------------+
			with | IPv6 Multicast Destination Address |
			BIER +------------------------------------+
			Routing| BIER RH(BitString = 00001100) |
			Header +------------------------------------+
			| Original multicast packet |
			+------------------------------------+
	Packet 1		Packet 2
	+------------------------------------+		+------------------------------------+
	IPv6 | IPv6 Address of Multicast Source |		Outer | Source IP Address = D |
	Header +------------------------------------+		IPv6 +------------------------------------+
	| IPv6 Multicast Destination Address |		Header | Destination IP Address = E |
	BIER +------------------------------------+		+------------------------------------+
	Routing| BitString = 00101100 |		Inner | IPv6 Address of A |
	Header +------------------------------------+		IPv6 +------------------------------------+
			Header | IPv6 Multicast Destination Address |
			with +------------------------------------+
			BIER | BIER RH(BitString = 00001100) |
			Routing+------------------------------------+
			Header | Original multicast packet |
			+------------------------------------+
	Packet 2		Packet 3
	+------------------------------------+		+-------------------------------------+
	Outer | Source IP Address = D |		IPv6 | IPv6 Address of A |
	IPv6 +------------------------------------+		Header +-------------------------------------+
	Header | Destination IP Address = E |		with | IPv6 Multicast Destination Address |
	+------------------------------------+		BIER +-------------------------------------+
	Inner | IPv6 Address of Multicast Source |		Routing| BIER RH(BitString = 00000100) |
	IPv6 +------------------------------------+		Header +-------------------------------------+
			| Original multicast packet |
			+-------------------------------------+
	Header | IPv6 Multicast Destination Address |		Figure 3: Some nodes in BIER domain do not support BIER Routing Header
	+------------------------------------+
	BIER | BitString = 00001100 |
	Routing+------------------------------------+
	Header
	Packet 3
	+-------------------------------------+
	IPv6 | IPv6 Address of Multicast Source |
	Header +-------------------------------------+
	| IPv6 Multicast Destination Address |
	BIER +-------------------------------------+
	Routing| BitString = 00000100 |
	Header +-------------------------------------+
	Figure 3: Some devices in BIER domain do not support BIER Routing Header		The topology is shown in Figure 3, all nodes expect node C support
			BIER Routing Header. The packet need to be transmitted from A to F.
			The change of the Header has been given in the Figure 3.
	The topology is shown in Figure 3, all devices expect device C		1). After receiving a multicast packet, node A encapsulates a IPv6
	support BIER Routing Header. The packet need to be transmitted from		Header with BIER Routing Header to it, and forwards the packet to
	A to F. The change of the Header has been given in the Figure 3.		node D according to the BIFT.
	When it is found that device C does not support BIER Routing Header,
	device D will perform the following steps after receiving the packet:
	1. Calculating the IPv6 address of next hop device(Node E) that		2). Node D calculates the IPv6 address of next hop node(Node E) that
	supports BIER Routing Header.		supports BIER Routing Header, and encapsulates an outer IPv6 Header
			to the packet. The source IPv6 address is the IPv6 address of
			itself, and the destination IPv6 address is the IPv6 address of node
			E. Then, sending the packet to node C.
	2. Encapsulating an outer IPv6 Header to the packet. The calculated		3). Node C performs normal IPv6 forwarding according to the outer
	IPv6 address(E) is used as the destination address of the outer IPv6		IPv6 header and sends the packet to node E.
	Header, and its own IPv6 address(D) is used as the source address of
	the outer IPv6 Header. BitString will not be changed.
	3. Sending the packet to directed-connected device C.		4). Node E decapsulates the outer IPv6 header and forwards the
			packet according to the BIFT to node F.
	After receiving the packet, device C will perform IPv6 forwarding		In the forwarding procedures, the source address and destination
	according the information in outer IPv6 Header, and send the packet		address in the Inner IPv6 Header are not changed, only the BitString
	to device E. Device E will send it to device F according the		in BIER Routing Header is updated.
	information in BIER Routing Header. In the forwarding process, the
	source address and destination address in the Inner IPv6 Header are
	not changed.
	5. Security Considerations		5. Security Considerations
	TBD		TBD
	6. IANA Considerations		6. IANA Considerations
	This document defines a new IPv6 Routing Header - BIER Routing		This document defines a new type of IPv6 Routing Header - BIER
	Header. The code point is from the "Internet Protocol Version 6		Routing Header. The code point is from the "Internet Protocol
	(IPv6) Parameters - Routing Types". It is recommended to set the		Version 6 (IPv6) Parameters - Routing Types". It is recommended to
	code point of BIER Routing Header to 7.		set the code point of BIER Routing Header to 7.
	7. References		7. References
	7.1. Normative References		7.1. Normative References
	[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>.
	skipping to change at page 9, line 27 ¶		skipping to change at page 10, line 5 ¶
	(IPv6) Specification", STD 86, RFC 8200,		(IPv6) Specification", STD 86, RFC 8200,
	DOI 10.17487/RFC8200, July 2017,		DOI 10.17487/RFC8200, July 2017,
	<https://www.rfc-editor.org/info/rfc8200>.		<https://www.rfc-editor.org/info/rfc8200>.
	[RFC8279] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A.,		[RFC8279] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A.,
	Przygienda, T., and S. Aldrin, "Multicast Using Bit Index		Przygienda, T., and S. Aldrin, "Multicast Using Bit Index
	Explicit Replication (BIER)", RFC 8279,		Explicit Replication (BIER)", RFC 8279,
	DOI 10.17487/RFC8279, November 2017,		DOI 10.17487/RFC8279, November 2017,
	<https://www.rfc-editor.org/info/rfc8279>.		<https://www.rfc-editor.org/info/rfc8279>.
			[RFC8296] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A.,
			Tantsura, J., Aldrin, S., and I. Meilik, "Encapsulation
			for Bit Index Explicit Replication (BIER) in MPLS and Non-
			MPLS Networks", RFC 8296, DOI 10.17487/RFC8296, January
			2018, <https://www.rfc-editor.org/info/rfc8296>.
	7.2. Informative References		7.2. Informative References
	[I-D.ietf-bier-bierin6]		[I-D.ietf-bier-bierin6]
	Zhang, Z., Zhang, Z., Wijnands, I., Mishra, M., Bidgoli,		Zhang, Z., Zhang, Z., Wijnands, I., Mishra, M., Bidgoli,
	H., and G. Mishra, "Supporting BIER in IPv6 Networks		H., and G. Mishra, "Supporting BIER in IPv6 Networks
	(BIERin6)", draft-ietf-bier-bierin6-00 (work in progress),		(BIERin6)", draft-ietf-bier-bierin6-01 (work in progress),
	June 2021.		December 2021.
	[I-D.xie-bier-ipv6-encapsulation]		[I-D.xie-bier-ipv6-encapsulation]
	Xie, J., Geng, L., McBride, M., Asati, R., Dhanaraj, S.,		Xie, J., Geng, L., McBride, M., Asati, R., Dhanaraj, S.,
	Zhu, Y., Qin, Z., Shin, M., Mishra, G., and X. Geng,		Zhu, Y., Qin, Z., Shin, M., Mishra, G., and X. Geng,
	"Encapsulation for BIER in Non-MPLS IPv6 Networks", draft-		"Encapsulation for BIER in Non-MPLS IPv6 Networks", draft-
	xie-bier-ipv6-encapsulation-10 (work in progress),		xie-bier-ipv6-encapsulation-10 (work in progress),
	February 2021.		February 2021.
	Authors' Addresses		Authors' Addresses
End of changes. 50 change blocks.
	141 lines changed or deleted		175 lines changed or added
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