draft-ietf-pim-drlb-11.txt		draft-ietf-pim-drlb-12.txt
	Network Working Group Y. Cai		Network Working Group Y. Cai
	Internet-Draft H. Ou		Internet-Draft H. Ou
	Intended status: Standards Track Alibaba Group		Intended status: Standards Track Alibaba Group
	Expires: April 13, 2020 S. Vallepalli		Expires: April 25, 2020 S. Vallepalli
	M. Mishra		M. Mishra
	S. Venaas		S. Venaas
	Cisco Systems, Inc.		Cisco Systems, Inc.
	A. Green		A. Green
	British Telecom		British Telecom
	October 11, 2019		October 23, 2019
	PIM Designated Router Load Balancing		PIM Designated Router Load Balancing
	draft-ietf-pim-drlb-11		draft-ietf-pim-drlb-12
	Abstract		Abstract
	On a multi-access network, one of the PIM-SM routers is elected as a		On a multi-access network, one of the PIM-SM routers is elected as a
	Designated Router. One of the responsibilities of the Designated		Designated Router. One of the responsibilities of the Designated
	Router is to track local multicast listeners and forward data to		Router is to track local multicast listeners and forward data to
	these listeners if the group is operating in PIM-SM. This document		these listeners if the group is operating in PIM-SM. This document
	specifies a modification to the PIM-SM protocol that allows more than		specifies a modification to the PIM-SM protocol that allows more than
	one of the PIM-SM routers to take on this responsibility so that the		one of the PIM-SM routers to take on this responsibility so that the
	forwarding load can be distributed among multiple routers.		forwarding load can be distributed among multiple routers.
	skipping to change at page 1, line 42 ¶		skipping to change at page 1, line 42 ¶
	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 13, 2020.		This Internet-Draft will expire on April 25, 2020.
	Copyright Notice		Copyright Notice
	Copyright (c) 2019 IETF Trust and the persons identified as the		Copyright (c) 2019 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 25 ¶		skipping to change at page 2, line 25 ¶
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
	2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5		2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
	3. Applicability . . . . . . . . . . . . . . . . . . . . . . . . 5		3. Applicability . . . . . . . . . . . . . . . . . . . . . . . . 5
	4. Functional Overview . . . . . . . . . . . . . . . . . . . . . 5		4. Functional Overview . . . . . . . . . . . . . . . . . . . . . 5
	4.1. GDR Candidates . . . . . . . . . . . . . . . . . . . . . 6		4.1. GDR Candidates . . . . . . . . . . . . . . . . . . . . . 6
	5. Protocol Specification . . . . . . . . . . . . . . . . . . . 7		5. Protocol Specification . . . . . . . . . . . . . . . . . . . 7
	5.1. Hash Mask and Hash Algorithm . . . . . . . . . . . . . . 7		5.1. Hash Mask and Hash Algorithm . . . . . . . . . . . . . . 7
	5.2. Modulo Hash Algorithm . . . . . . . . . . . . . . . . . . 8		5.2. Modulo Hash Algorithm . . . . . . . . . . . . . . . . . . 8
	5.2.1. Modulo Hash Algorithm Example . . . . . . . . . . . . 9		5.2.1. Modulo Hash Algorithm Examples . . . . . . . . . . . 9
	5.2.2. Limitations . . . . . . . . . . . . . . . . . . . . . 10		5.2.2. Limitations . . . . . . . . . . . . . . . . . . . . . 10
	5.3. PIM Hello Options . . . . . . . . . . . . . . . . . . . . 10		5.3. PIM Hello Options . . . . . . . . . . . . . . . . . . . . 10
	5.3.1. PIM DR Load Balancing Capability (DRLB-Cap) Hello		5.3.1. PIM DR Load Balancing Capability (DRLB-Cap) Hello
	Option . . . . . . . . . . . . . . . . . . . . . . . 10		Option . . . . . . . . . . . . . . . . . . . . . . . 11
	5.3.2. PIM DR Load Balancing List (DRLB-List) Hello Option . 11		5.3.2. PIM DR Load Balancing List (DRLB-List) Hello Option . 11
	5.4. PIM DR Operation . . . . . . . . . . . . . . . . . . . . 12		5.4. PIM DR Operation . . . . . . . . . . . . . . . . . . . . 13
	5.5. PIM GDR Candidate Operation . . . . . . . . . . . . . . . 13		5.5. PIM GDR Candidate Operation . . . . . . . . . . . . . . . 13
	5.6. DRLB-List Hello Option Processing . . . . . . . . . . . . 13		5.6. DRLB-List Hello Option Processing . . . . . . . . . . . . 14
	5.7. PIM Assert Modification . . . . . . . . . . . . . . . . . 14		5.7. PIM Assert Modification . . . . . . . . . . . . . . . . . 15
	5.8. Backward Compatibility . . . . . . . . . . . . . . . . . 16		5.8. Backward Compatibility . . . . . . . . . . . . . . . . . 16
	6. Manageability Considerations . . . . . . . . . . . . . . . . 16		6. Operational Considerations . . . . . . . . . . . . . . . . . 16
	7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17		7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
	7.1. Initial registry . . . . . . . . . . . . . . . . . . . . 17		7.1. Initial registry . . . . . . . . . . . . . . . . . . . . 17
	7.2. Assignment of new hash algorithms . . . . . . . . . . . . 17		7.2. Assignment of new Hash Algorithms . . . . . . . . . . . . 17
	8. Security Considerations . . . . . . . . . . . . . . . . . . . 17		8. Security Considerations . . . . . . . . . . . . . . . . . . . 17
	9. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 18		9. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 18
	10. References . . . . . . . . . . . . . . . . . . . . . . . . . 18		10. References . . . . . . . . . . . . . . . . . . . . . . . . . 18
	10.1. Normative References . . . . . . . . . . . . . . . . . . 18		10.1. Normative References . . . . . . . . . . . . . . . . . . 18
	10.2. Informative References . . . . . . . . . . . . . . . . . 18		10.2. Informative References . . . . . . . . . . . . . . . . . 18
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19
	1. Introduction		1. Introduction
	On a multi-access LAN, such as an Ethernet, with one or more PIM-SM		On a multi-access LAN, such as an Ethernet, with one or more PIM-SM
	skipping to change at page 5, line 22 ¶		skipping to change at page 5, line 22 ¶
	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.
	With respect to PIM-SM, this document follows the terminology that		With respect to PIM-SM, this document follows the terminology that
	has been defined in [RFC7761].		has been defined in [RFC7761].
	This document also introduces the following new acronyms:		This document also introduces the following new acronyms:
	o GDR: Group Designated Router. For each multicast flow, either a		o GDR: Group Designated Router. For each multicast flow, either a
	(*,G) for Any-Source Multicast (ASM), or an (S,G) for Source-		(*,G) for Any-Source Multicast (ASM), or an (S,G) for Source-
	Specific Multicast (SSM) [RFC4607], a hash algorithm (described		Specific Multicast (SSM) [RFC4607], a Hash Algorithm (described
	below) is used to select one of the routers as a GDR. The GDR is		below) is used to select one of the routers as a GDR. The GDR is
	responsible for initiating the forwarding tree building process		responsible for initiating the forwarding tree building process
	for the corresponding multicast flow.		for the corresponding multicast flow.
	o GDR Candidate: a router that has the potential to become a GDR.		o GDR Candidate: a router that has the potential to become a GDR.
	There might be multiple GDR Candidates on a LAN, but only one can		There might be multiple GDR Candidates on a LAN, but only one can
	become the GDR for a specific multicast flow.		become the GDR for a specific multicast flow.
	3. Applicability		3. Applicability
	skipping to change at page 6, line 14 ¶		skipping to change at page 6, line 14 ¶
	with those of its neighbors. The router with the highest DR priority		with those of its neighbors. The router with the highest DR priority
	is the PIM DR. If there are multiple such routers, their IP		is the PIM DR. If there are multiple such routers, their IP
	addresses are used as the tie-breaker, as described in [RFC7761].		addresses are used as the tie-breaker, as described in [RFC7761].
	In order to share forwarding load among last hop routers, besides the		In order to share forwarding load among last hop routers, besides the
	normal PIM DR election, the GDR is also elected on the multi-access		normal PIM DR election, the GDR is also elected on the multi-access
	LAN. There is only one PIM DR on the multi-access LAN, but there		LAN. There is only one PIM DR on the multi-access LAN, but there
	might be multiple GDR Candidates.		might be multiple GDR Candidates.
	For each multicast flow, that is, (*,G) for ASM and (S,G) for SSM, a		For each multicast flow, that is, (*,G) for ASM and (S,G) for SSM, a
	hash algorithm is used to select one of the routers to be the GDR. A		Hash Algorithm is used to select one of the routers to be the GDR.
	new DR Load Balancing Capability (DRLB-Cap) PIM Hello Option, which		The new DR Load Balancing Capability (DRLB-Cap) PIM Hello Option is
	contains hash algorithm type, is announced by routers on interfaces		used to announce the Capability as well as the Hash Algorithm type.
	where this specification is enabled. Routers with the new DRLB-Cap		Routers with the new DRLB-Cap Option advertised in their PIM Hello,
	Option advertised in their PIM Hello, using the same GDR election		using the same GDR election Hash Algorithm and the same DR priority
	hash algorithm and the same DR priority as the PIM DR, are considered		as the PIM DR, are considered as GDR Candidates.
	as GDR Candidates.
	Hash Masks are defined for Source, Group and RP separately, in order		Hash Masks are defined for Source, Group and RP separately, in order
	to handle PIM ASM/SSM. The masks, as well as a sorted list of GDR		to handle PIM ASM/SSM. The masks, as well as a sorted list of GDR
	Candidate Addresses, are announced by the DR in a new DR Load		Candidate Addresses, are announced by the DR in a new DR Load
	Balancing List (DRLB-List) PIM Hello Option.		Balancing List (DRLB-List) PIM Hello Option.
	A hash algorithm based on the announced Source, Group, or RP masks		A Hash Algorithm based on the announced Source, Group, or RP masks
	allows one GDR to be assigned to a corresponding multicast state.		allows one GDR to be assigned to a corresponding multicast state.
	And that GDR is responsible for initiating the creation of the		And that GDR is responsible for initiating the creation of the
	multicast forwarding tree for multicast traffic.		multicast forwarding tree for multicast traffic.
	4.1. GDR Candidates		4.1. GDR Candidates
	GDR is the new concept introduced by this specification. GDR		GDR is the new concept introduced by this specification. GDR
	Candidates are routers eligible for GDR election on the LAN. To		Candidates are routers eligible for GDR election on the LAN. To
	become a GDR Candidate, a router must have the same DR priority and		become a GDR Candidate, a router must have the same DR priority and
	run the same GDR election hash algorithm as the DR on the LAN.		run the same GDR election Hash Algorithm as the DR on the LAN.
	For example, assume there are 4 routers on the LAN: R1, R2, R3 and		For example, assume there are 4 routers on the LAN: R1, R2, R3 and
	R4, each announcing a DRLB-Cap option. R1, R2 and R3 have the same		R4, each announcing a DRLB-Cap option. R1, R2 and R3 have the same
	DR priority while R4's DR priority is less preferred. In this		DR priority while R4's DR priority is less preferred. In this
	example, R4 will not be eligible for GDR election, because R4 will		example, R4 will not be eligible for GDR election, because R4 will
	not become a PIM DR unless all of R1, R2 and R3 go out of service.		not become a PIM DR unless all of R1, R2 and R3 go out of service.
	Furthermore, assume router R1 wins the PIM DR election, R1 and R2 run		Furthermore, assume router R1 wins the PIM DR election, R1 and R2 run
	the same hash algorithm for GDR election, while R3 runs a different		the same Hash Algorithm for GDR election, while R3 runs a different
	one. In this case, only R1 and R2 will be eligible for GDR election,		one. In this case, only R1 and R2 will be eligible for GDR election,
	while R3 will not.		while R3 will not.
	As a DR, R1 will include its own Load Balancing Hash Masks and the		As a DR, R1 will include its own Load Balancing Hash Masks and the
	identity of R1 and R2 (the GDR Candidates) in its DRLB-List Hello		identity of R1 and R2 (the GDR Candidates) in its DRLB-List Hello
	Option.		Option.
	5. Protocol Specification		5. Protocol Specification
	5.1. Hash Mask and Hash Algorithm		5.1. Hash Mask and Hash Algorithm
	A Hash Mask is used to extract a number of bits from the		A Hash Mask is used to extract a number of bits from the
	corresponding IP address field (32 for IPv4, 128 for IPv6) and		corresponding IP address field (32 for IPv4, 128 for IPv6) and
	calculate a hash value. A hash value is used to select a GDR from		calculate a hash value. A hash value is used to select a GDR from
	GDR Candidates advertised by PIM DR. For example, 0.0.255.0 defines		GDR Candidates advertised by the PIM DR. Hash masks allow for
	a Hash Mask for an IPv4 address that masks the first, the second, and		certain flows to always be forwarded by the same GDR, by ignoring
	the fourth octets. Hash masks allow for certain flows to always be		certain bits in the hash value calculation, so that the hash values
	forwarded by the same GDR, since the hash values are the same. For		are the same. For example, 0.0.255.0 defines a Hash Mask for an IPv4
	instance the mask 0.0.255.0 means that only the third octet will be		address that masks the first, the second, and the fourth octets,
	considered when hashing.		which means that only the third octet will influence the hash value
			computed.
	In the text below, a hash mask is in some places said to be zero. A		In the text below, a hash mask is in some places said to be zero. A
	hash mask is zero if no bits are set. That is, 0.0.0.0 for IPv4 and		hash mask is zero if no bits are set. That is, 0.0.0.0 for IPv4 and
	:: for IPv6. Also, a hash mask is said to be an all-bits-set mask if		:: for IPv6. Also, a hash mask is said to be an all-bits-set mask if
	it is 255.255.255.255 for IPv4 or		it is 255.255.255.255 for IPv4 or
	FFFF:FFFF:FFFF:FFFF:FFFFF:FFFF:FFFF:FFFF for IPv6.		FFFF:FFFF:FFFF:FFFF:FFFFF:FFFF:FFFF:FFFF for IPv6.
	There are three Hash Masks defined:		There are three Hash Masks defined:
	o RP Hash Mask		o RP Hash Mask
	skipping to change at page 8, line 16 ¶		skipping to change at page 8, line 12 ¶
	PIM DR is not zero (at least one bit is set), calculate the value		PIM DR is not zero (at least one bit is set), calculate the value
	of hashvalue_RP [Section 5.2] to determine the GDR.		of hashvalue_RP [Section 5.2] to determine the GDR.
	o If the group is in ASM mode and the RP Hash Mask announced by the		o If the group is in ASM mode and the RP Hash Mask announced by the
	PIM DR is zero (no bits are set), obtain the value of		PIM DR is zero (no bits are set), obtain the value of
	hashvalue_Group [Section 5.2] to determine the GDR.		hashvalue_Group [Section 5.2] to determine the GDR.
	o If the group is in SSM mode, use hashvalue_SG [Section 5.2] to		o If the group is in SSM mode, use hashvalue_SG [Section 5.2] to
	determine the GDR.		determine the GDR.
	A simple Modulo hash algorithm is defined in this document. However,		A simple Modulo Hash Algorithm is defined in this document. However,
	to allow another hash algorithms to be used, a 1-octet "Hash		to allow another Hash Algorithms to be used, a 1-octet "Hash
	Algorithm" field is included in the DRLB-Cap Hello Option to specify		Algorithm" field is included in the DRLB-Cap Hello Option to specify
	the hash algorithm used by the router.		the Hash Algorithm used by the router.
	If different hash algorithms are advertised among the routers on a		If different Hash Algorithms are advertised among the routers on a
	LAN, only the outers advertising the same hash algorithm as the DR		LAN, only the routers advertising the same Hash Algorithm as the DR
	(as well as having the same DR priority as the DR) are eligible for		(as well as having the same DR priority as the DR) are eligible for
	GDR election.		GDR election.
	5.2. Modulo Hash Algorithm		5.2. Modulo Hash Algorithm
	As part of computing the hash, the notation LSZC(hash_mask) is used		As part of computing the hash, the notation LSZC(hash_mask) is used
	to denote the number of zeroes counted from the least significant bit		to denote the number of zeroes counted from the least significant bit
	of a Hash Mask hash_mask. As an example, LSZC(255.255.128) is 7 and		of a Hash Mask hash_mask. As an example, LSZC(255.255.128) is 7 and
	also LSZC(FFFF:8000::) is 111. If all bits are set, LSZC will be 0.		also LSZC(FFFF:8000::) is 111. If all bits are set, LSZC will be 0.
	If the mask is zero, then LSZC will be 32 for IPv4, and 128 for IPv6.		If the mask is zero, then LSZC will be 32 for IPv4, and 128 for IPv6.
	The number of GDR Candidates is denoted as GDRC.		The number of GDR Candidates is denoted as GDRC.
	The idea behind the Modulo hash algorithm is in simple terms that the		The idea behind the Modulo Hash Algorithm is in simple terms that the
	corresponding mask is applied to a value, then the result is shifted		corresponding mask is applied to a value, then the result is shifted
	right LSZC(mask) bits so that the least significant bits that were		right LSZC(mask) bits so that the least significant bits that were
	masked out are not considered. Then this result is masked by 0xFFFF,		masked out are not considered. Then this result is masked by 0xFFFF,
	keeping only the last 32 bits of the result (this only makes a		keeping only the last 32 bits of the result (this only makes a
	difference for IPv6). Finally, the hash value is this result modulo		difference for IPv6). Finally, the hash value is this result modulo
	the number of GDR Candidates (GDRC).		the number of GDR Candidates (GDRC).
	The Modulo hash algorithm for computing the values hashvalue_RP,		The Modulo Hash Algorithm for computing the values hashvalue_RP,
	hashvalue_Group and hashvalue_SG is defined as follows.		hashvalue_Group and hashvalue_SG is defined as follows.
	hashvalue_RP is calculated as:		hashvalue_RP is calculated as:
	(((RP_address & RP_mask) >> LSZC(RP_mask)) & 0xFFFF) % GDRC		(((RP_address & RP_mask) >> LSZC(RP_mask)) & 0xFFFF) % GDRC
	RP_address is the address of the RP defined for the group and		RP_address is the address of the RP defined for the group and
	RP_mask is the RP Hash Mask.		RP_mask is the RP Hash Mask.
	hashvalue_Group is calculated as:		hashvalue_Group is calculated as:
	skipping to change at page 9, line 22 ¶		skipping to change at page 9, line 20 ¶
	hashvalue_SG is calculated as:		hashvalue_SG is calculated as:
	((((Source_address & Source_mask) >> LSZC(Source_mask)) & 0xFFFF)		((((Source_address & Source_mask) >> LSZC(Source_mask)) & 0xFFFF)
	^ (((Group_address & Group_mask) >> LSZC(Group_mask)) & 0xFFFF)) %		^ (((Group_address & Group_mask) >> LSZC(Group_mask)) & 0xFFFF)) %
	GDRC		GDRC
	Group_address is the group address and Group_mask is the Group		Group_address is the group address and Group_mask is the Group
	Hash Mask.		Hash Mask.
	5.2.1. Modulo Hash Algorithm Example		5.2.1. Modulo Hash Algorithm Examples
	To help illustrate the algorithm, consider this example. Router X		To help illustrate the algorithm, consider this example. Router X
	with IPv4 address 203.0.113.1 receives a DRLB-List Hello Option from		with IPv4 address 203.0.113.1 receives a DRLB-List Hello Option from
	the DR, which announces RP Hash Mask 0.0.255.0 and a list of GDR		the DR, which announces RP Hash Mask 0.0.255.0 and a list of GDR
	Candidates, sorted by IP addresses from high to low: 203.0.113.3,		Candidates, sorted by IP addresses from high to low: 203.0.113.3,
	203.0.113.2 and 203.0.113.1. The ordinal number assigned to those		203.0.113.2 and 203.0.113.1. The ordinal number assigned to those
	addresses would be:		addresses would be:
	0 for 203.0.113.3; 1 for 203.0.113.2; 2 for 203.0.113.1 (Router X)		0 for 203.0.113.3; 1 for 203.0.113.2; 2 for 203.0.113.1 (Router X).
	Assume there are 2 RPs: RP1 192.0.2.1 for Group1 and RP2 198.51.100.2		Assume there are 2 RPs: RP1 192.0.2.1 for Group1 and RP2 198.51.100.2
	for Group2. Following the modulo hash algorithm:		for Group2. Following the modulo Hash Algorithm:
	LSZC(0.0.255.0) is 8 and GDRC is 3. The hashvalue_RP for Group1 with		LSZC(0.0.255.0) is 8 and GDRC is 3. The hashvalue_RP for Group1 with
	RP RP1 is:		RP RP1 is:
	(((192.0.2.1 & 0.0.255.0) >> 8) & 0xFFFF % 3) = 2 % 3 = 2		(((192.0.2.1 & 0.0.255.0) >> 8) & 0xFFFF % 3) = 2 % 3 = 2
	which matches the ordinal number assigned to Router X. Router X will		which matches the ordinal number assigned to Router X. Router X will
	be the GDR for Group1.		be the GDR for Group1.
	The hashvalue_RP for Group2 with RP RP2 is:		The hashvalue_RP for Group2 with RP RP2 is:
	(((198.51.100.2 & 0.0.255.0) >> 8) & 0xFFFF % 3) = 100 % 3 = 1		(((198.51.100.2 & 0.0.255.0) >> 8) & 0xFFFF % 3) = 100 % 3 = 1
	which is different from the ordinal number of router X (2). Hence,		which is different from the ordinal number of router X (2). Hence,
	Router X will not be GDR for Group2.		Router X will not be GDR for Group2.
			For IPv6 consider this example, similar to the above. Router X with
			IPv6 address FE80::1 receives a DRLB-List Hello Option from the DR,
			which announces RP Hash Mask ::FFFF:FFFF:0 and a list of GDR
			Candidates, sorted by IP addresses from high to low: FE80::3, FE80::2
			and FE80::1. The ordinal number assigned to those addresses would
			be:
			0 for FE80::3; 1 for FE80::2; 2 for FE80::1 (Router X).
			Assume there are 2 RPs: RP1 2001:DB8::1:5678:1 for Group1 and RP2
			2001:DB8::1:1234:2 for Group2. Following the modulo Hash Algorithm:
			LSZC(::FFFF:FFFF:0) is 32 and GDRC is 3. The hashvalue_RP for Group1
			with RP RP1 is:
			(((2001:DB8::1:5678:1 & ::FFFF:FFFF:0) >> 32) & 0xFFFF % 3) =
			((::1:5678:0 >> 32) & 0xFFFF % 3) = (::1:5678 & 0xFFFF % 3) = ::5678
			% 3 = 2
			which matches the ordinal number assigned to Router X. Router X will
			be the GDR for Group1.
			The hashvalue_RP for Group2 with RP RP2 is:
			(((2001:DB8::1:1234:1 & ::FFFF:FFFF:0) >> 32) & 0xFFFF % 3) =
			((::1:1234:0 >> 32) & 0xFFFF % 3) = (::1:1234 & 0xFFFF % 3) = ::1234
			% 3 = 1
			which is different from the ordinal number of router X (2). Hence,
			Router X will not be GDR for Group2.
	5.2.2. Limitations		5.2.2. Limitations
	The Modulo Hash Algorithm has poor failover characteristics when a		The Modulo Hash Algorithm has poor failover characteristics when a
	shared LAN has more than two GDRs. In the case of more than two GDRs		shared LAN has more than two GDRs. In the case of more than two GDRs
	on a LAN, when one GDR fails, all of the groups may be reassigned to		on a LAN, when one GDR fails, all of the groups may be reassigned to
	a different GDR, even if they were not assigned to the failed GDR.		a different GDR, even if they were not assigned to the failed GDR.
	However, many deployments use only two routers on a shared LAN for		However, many deployments use only two routers on a shared LAN for
	redundancy purposes. Future work may define new hash algorithms		redundancy purposes. Future work may define new Hash Algorithms
	where only groups assigned to the failed GDR get reassigned.		where only groups assigned to the failed GDR get reassigned.
	5.3. PIM Hello Options		5.3. PIM Hello Options
	When a PIM router sends a PIM Hello on an interface with this		All PIM routers include a new option, called "Load Balancing
	specification enabled, it includes a new option, called "Load		Capability (DRLB-Cap)" in their PIM Hello messages.
	Balancing Capability (DRLB-Cap)".
	Besides this DRLB-Cap Hello Option, the elected PIM DR also includes		Besides this DRLB-Cap Hello Option, the elected PIM DR also includes
	a new "DR Load Balancing List (DRLB-List) Hello Option". The DRLB-		a new "DR Load Balancing List (DRLB-List) Hello Option". The DRLB-
	List Hello Option consists of three Hash Masks as defined above and		List Hello Option consists of three Hash Masks as defined above and
	also a sorted list of GDR Candidate addresses on the LAN.		also a sorted list of GDR Candidate addresses on the LAN.
	5.3.1. PIM DR Load Balancing Capability (DRLB-Cap) Hello Option		5.3.1. PIM DR Load Balancing Capability (DRLB-Cap) Hello Option
	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
	skipping to change at page 10, line 44 ¶		skipping to change at page 11, line 23 ¶
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Figure 3: PIM DR Load Balancing Capability Hello Option		Figure 3: PIM DR Load Balancing Capability Hello Option
	Type: 34		Type: 34
	Length: 4		Length: 4
	Reserved: Transmitted as zero, ignored on receipt.		Reserved: Transmitted as zero, ignored on receipt.
	Hash Algorithm: Hash algorithm type. 0 for the Modulo algorithm		Hash Algorithm: Hash Algorithm type. 0 for the Modulo algorithm
	defined in this document.		defined in this document.
	This DRLB-Cap Hello Option MUST be advertised by routers on all		This DRLB-Cap Hello Option MUST be advertised by routers on all
	interfaces where DR Load Balancing is enabled.		interfaces where DR Load Balancing is enabled.
	5.3.2. PIM DR Load Balancing List (DRLB-List) Hello Option		5.3.2. PIM DR Load Balancing List (DRLB-List) Hello Option
	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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	skipping to change at page 11, line 24 ¶		skipping to change at page 12, line 4 ¶
	| Source Mask |		| Source Mask |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| RP Mask |		| RP Mask |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| GDR Candidate Address(es) |		| GDR Candidate Address(es) |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Figure 4: PIM DR Load Balancing List Hello Option		Figure 4: PIM DR Load Balancing List Hello Option
	Type: 35		Type: 35
			Length: (3 + n) x (4 or 16) bytes, where n is the number of GDR
	Length: (3 + n) x (4 or 16), where n is the number of GDR
	candidates.		candidates.
	Group Mask (32/128 bits): Mask applied to group addresses as part		Group Mask (32/128 bits): Mask applied to group addresses as part
	of hash computation.		of hash computation.
	Source Mask (32/128 bits): Mask applied to source addresses as		Source Mask (32/128 bits): Mask applied to source addresses as
	part of hash computation.		part of hash computation.
	RP Mask (32/128 bits): Mask applied to RP addresses as part of		RP Mask (32/128 bits): Mask applied to RP addresses as part of
	hash computation.		hash computation.
	All masks MUST have the same number of bits as the IP source		All masks MUST have the same number of bits as the IP source
	address in the PIM Hello IP header.		address in the PIM Hello IP header.
	GDR Address (32/128 bits): Address(es) of GDR Candidate(s)		GDR Candidate Address(es) (32/128 bits): List of GDR Candidate(s)
	All addresses MUST be in the same address family as the PIM		All addresses MUST be in the same address family as the PIM
	Hello IP header. It is RECOMMENDED that the addresses are		Hello IP header. It is RECOMMENDED that the addresses are
	sorted in descending order.		sorted in descending order.
	If the "Interface ID" option, as specified in [RFC6395], is		If the "Interface ID" option, as specified in [RFC6395], is
	present in a GDR Candidate's PIM Hello message, and the "Router		present in a GDR Candidate's PIM Hello message, and the "Router
	ID" portion is non-zero:		Identifier" portion is non-zero:
	+ For IPv4, the "GDR Candidate Address" will be set directly		+ For IPv4, the "GDR Candidate Address" will be set directly
	to the "Router ID".		to the "Router Identifier".
	+ For IPv6, the "GDR Candidate Address" will be 96 bits of		+ For IPv6, the "GDR Candidate Address" will be 96 bits of
	zeroes followed by the 32 bit Router ID.		zeroes followed by the 32 bit Router Identifier.
	If the "Interface ID" option is not present in a GDR Candidate'		If the "Interface ID" option is not present in a GDR Candidate'
	PIM Hello message, or if the "Interface ID" option is present		PIM Hello message, or if the "Interface ID" option is present
	but the "Router ID" field is zero, the "GDR Candidate Address"		but the "Router Identifier" field is zero, the "GDR Candidate
	will be the IPv4 or IPv6 source address of the PIM Hello		Address" will be the IPv4 or IPv6 source address of the PIM
	message.		Hello message.
	This DRLB-List Hello Option MUST only be advertised by the		This DRLB-List Hello Option MUST only be advertised by the
	elected PIM DR. It MUST be ignored if received from a non-DR.		elected PIM DR. It MUST be ignored if received from a non-DR.
			The option MUST also be ignored if the hash masks are not the
			correct number of bits, or GDR Candidate addresses are in the
			wrong address family.
	5.4. PIM DR Operation		5.4. PIM DR Operation
	The DR election process is still the same as defined in [RFC7761]. A		The DR election process is still the same as defined in [RFC7761].
	DR that has this specification enabled on an interface advertises the		The DR advertises the new DRLB-List Hello Option, which contains mask
	new DRLB-List Hello Option, which contains mask values from user		values from user configuration (or default values), followed by a
	configuration (or default values), followed by a list of GDR		list of GDR Candidate Addresses. It is RECOMMENDED that the list be
	Candidate Addresses. It is RECOMMENDED that the list is sorted, from		sorted, from the highest value to the lowest value. The reason for
	the highest value to the lowest value. The reason for sorting the		sorting the list is to make the behavior deterministic, regardless of
	list is to make the behavior deterministic, regardless of the order		the order in which the DR learns of new candidates. Note that, as
	the DR learns of new candidates. Note that same as non-DR routers,		non-DR routers, the DR also advertises the DRLB-Cap Hello Option to
	the DR also advertises DRLB-Cap Hello Option to indicate its		indicate its ability to support the new functionality and the type of
	capability of supporting this specification and the type of its GDR		GDR election Hash Algorithm.
	election hash algorithm.
	If a PIM DR receives a neighbor DRLB-Cap Hello Option, which contains		If a PIM DR receives a neighbor DRLB-Cap Hello Option, which contains
	the same hash algorithm as the DR, and the neighbor has the same DR		the same Hash Algorithm as the DR, and the neighbor has the same DR
	priority as the DR, PIM DR SHOULD consider the neighbor as a GDR		priority as the DR, PIM DR SHOULD consider the neighbor as a GDR
	Candidate and insert the GDR Candidate' Address into the list of the		Candidate and insert the GDR Candidate' Address into the list of the
	DRLB-List Option. However, the DR may have policies limiting which		DRLB-List Option. However, the DR may have policies limiting which
	GDR Candidates, or the number of GDR Candidates to include. The DR		GDR Candidates, or the number of GDR Candidates to include.
	would normally include itself in the list of GDR Candidates.		Likewise, the DR SHOULD include itself in the list of GDR Candidates,
			but it is permissable not to do so, if for instance there is some
			policy restricting the candidate set.
	If a PIM neighbor included in the list expires, stops announcing the		If a PIM neighbor included in the list expires, stops announcing the
	DRLB-Cap Hello Option, changes DR priority, changes hash algorithm or		DRLB-Cap Hello Option, changes DR priority, changes Hash Algorithm or
	otherwise becomes ineligibile as a candidate, the DR should		otherwise becomes ineligible as a candidate, the DR SHOULD
	immediately send a triggered hello with a new list in the DRLB-List		immediately send a triggered hello with a new list in the DRLB-List
	option, excluding the neighbor.		option, excluding the neighbor.
	If a new router becomes eligible as a candidate, there is no urgency		If a new router becomes eligible as a candidate, there is no urgency
	in sending out an updated list. An updated list SHOULD be included		in sending out an updated list. An updated list SHOULD be included
	in the next hello.		in the next hello.
	5.5. PIM GDR Candidate Operation		5.5. PIM GDR Candidate Operation
	When an IGMP/MLD report is received, without this specification, only		When an IGMP/MLD report is received, a Hash Algorithm is used by the
	the PIM DR will handle the join and potentially run into the issues		GDR Candidates to determine which router is going to be responsible
	described earlier. Using this specification, a hash algorithm is		for building forwarding trees on behalf of the host.
	used by the GDR Candidates to determine which router is going to be
	responsible for building forwarding trees on behalf of the host.
	If this specification is enabled on an interface, the router MUST		The router MUST include the DRLB-Cap Hello Option in all PIM Hello
	include the DRLB-Cap Hello Option in all PIM Hello messages sent on		messages sent on the interface. Note that the presence of the DRLB-
	that interface. Note that the presence of the DRLB-Cap Option in PIM		Cap Option in the PIM Hello does not guarantee that the router will
	Hello does not guarantee that this router would be considered as a		be considered as a GDR candidate. Once the DR election is done, the
	GDR candidate. Once DR election is done, the DRLB-List Hello Option		DRLB-List Hello Option is received from the current PIM DR containing
	would be received from the current PIM DR on the link which would		a list of the selected GDRs Candidates.
	contain a list of GDRs Candidates selected by the PIM DR.
	A router only acts as a GDR Candidate if it is included in the GDR		A router only acts as a GDR Candidate if it is included in the GDR
	Candidate list of the DRLB-List Hello Option. See next section for		Candidate list of the DRLB-List Hello Option. See next section for
	details.		details.
	5.6. DRLB-List Hello Option Processing		5.6. DRLB-List Hello Option Processing
	This section discusses processing of the DRLB-List Hello Option. All		This section discusses processing of the DRLB-List Hello Option,
	routers MUST ignore the DRLB-List Hello Option if it is received from		including the case where it was received in the previous hello, but
	a PIM router which is not the DR. The option MUST only be processed		not in the current hello. All routers MUST ignore the DRLB-List
	by routers that are announcing the DRLB-Cap Option. Also, the		Hello Option if it is received from a PIM router which is not the DR.
	algorithm announced in the DRLB-Cap Option, MUST be the same as what		The option MUST only be processed by routers that are announcing the
	was announced by the DR. All GDR Candidates MUST use the Hash Masks		DRLB-Cap Option, and only if the Hash Algorithm announced by the DR
	advertised in the Option, even if they differ from those the		is the same as the local announcement. All GDR Candidates MUST use
	candidate was configured with.		the Hash Masks advertised in the Option, even if they differ from
			those the candidate was configured with. The DR MUST also process
			its own DRLB-List Hello Option.
	A router stores the latest option contents that was announced, if		A router stores the latest option contents that was announced, if
	any, and deletes the previous contents. The router MUST also compare		any, and deletes the previous contents. The router MUST also compare
	the new contents with any previous contents, and if there are any		the new contents with any previous contents, and if there are any
	changes, continue processing as below. Note that if the option does		changes, continue processing as below. Note that if the option does
	not pass the above checks, the below processing MUST be done as if		not pass the above checks, the below processing MUST be done as if
	the option was not announced.		the option was not announced.
	If the contents of the DRLB-List Option, the masks or the candidate		If the contents of the DRLB-List Option, the masks or the candidate
	list, differs from the previously saved copy, it is received for the		list, differs from the previously saved copy, it is received for the
	first time, or it is no longer being received or accepted, the option		first time, or it is no longer being received or accepted, the option
	MUST be processed as below.		MUST be processed as below.
	1. If the router was not included in the previous GDR list, or there		1. If the local router is included in the GDR Candidate Address(es)
	was no previous GDR list, but it is included in the new GDR list,		field, for each of the groups, or source and group pairs if the
	the router MUST for each of the groups, or source and group pairs		group is in SSM mode, with local receiver interest, the router
	if the group is in SSM mode, with local receiver interest, run		MUST run the Hash Algorithm to determine which of them it is the
	the hash algorithm to determine which of them it is the GDR for.		GDR for.
	If it is not the GDR for a group, or source and group pair if
	SSM, no processing is required.
	If it is hashed as the GDR, it needs to build a multicast
	forwarding tree.
	2. If the router was included in the previous GDR list, and still is		If there is no change in the GDR status, then no further
	included in the new GDR list: The router MUST for each of the		action is required.
	groups, or source and group pairs if the group is in SSM mode,
	with local receiver interest, run the hash algorithm to determine
	which of them it is the GDR for.
	If it was the GDR for a group, or source and group pair if		If the router becomes the new GDR, then a multicast forwarding
	SSM, and the new hash result chose it as the GDR, then no		tree MUST be built [RFC7761].
	processing is required.
	If it was the GDR for a group, or source and group pair if		If the router is no longer the GDR, then it uses an Assert as
	SSM, earlier and now it is no longer the GDR, then it sets the
	assert metric preference to maximum (0x7FFFFFFF) and the
	assert metric to one less than maximum (0xFFFFFFFE), as
	explained in [Section 5.7].		explained in [Section 5.7].
	If it was not the GDR for a group, or source and group pair if		2. If the local router is not included in the GDR Candidate
	SSM, earlier, and the new hash does not make it GDR, then no		Address(es) field, or if the DRLB-List Hello Option is no longer
	processing is required.		included in the DR's Hello, or if the DR's Neighbor Liveness
			Timer expires [RFC7761], for each of the groups, or source and
	If it was not the GDR for an earlier group, or source and		group pairs if the group is in SSM mode, with local receiver
	group pair if SSM, and now becomes the GDR, it starts building		interest, for which the router is the GDR, it uses an Assert as
	multicast forwarding tree for this flow.		explained in [Section 5.7].
	3. If the router was included in the previous GDR list, but is not
	included in the new GDR list, or there is no new GDR list: The
	router MUST for each of the groups, or source and group pairs if
	the group is in SSM mode, with local receiver interest do as
	follows.
	If it was the GDR for a group, or source and group pair if
	SSM, it sets the assert metric preference to maximum
	(0x7FFFFFFF) and the assert metric to one less than maximum
	(0xFFFFFFFE), as explained in [Section 5.7].
	If it was not the GDR, then no processing is required.
	5.7. PIM Assert Modification		5.7. PIM Assert Modification
	GDR changes may occur due to configuration change, due to GDR		GDR changes may occur due to configuration change, due to GDR
	candidates going down, and also new routers coming up and becoming		candidates going down, and also new routers coming up and becoming
	GDR candidates. This may occur while flows are being forwarded. If		GDR candidates. This may occur while flows are being forwarded. If
	the GDR for an active flow changes, there is likely to be some		the GDR for an active flow changes, there is likely to be some
	disruption, such as packet loss or duplicates. By using asserts,		disruption, such as packet loss or duplicates. By using asserts,
	packet loss is minimized, while allowing a small amount of		packet loss is minimized, while allowing a small amount of
	duplicates.		duplicates.
	When a router stops acting as the GDR for a group, or source and		When a router stops acting as the GDR for a group, or source and
	group pair if SSM, it MUST set the assert metric preference to		group pair if SSM, it MUST set the Assert metric preference to
	maximum (0x7FFFFFFF) and the assert metric to one less than maximum		maximum (0x7FFFFFFF) and the Assert metric to one less than maximum
	(0xFFFFFFFE). This was also mentioned in the previous section. That		(0xFFFFFFFE). This was also mentioned in the previous section. That
	is, whenever it sends or receives an assert for the group, it must		is, whenever it sends or receives an Assert for the group, it must
	use these values as the metric preference and metric rather than the		use these values as the metric preference and metric rather than the
	values provided by routing. This is similar to what is done for		values provided by the unicast routing protocol.
	AssertCancel Messages in [RFC7761], except that the metric value here
	is one less.
	The rest of this section is just for illustration purposes and not		The rest of this section is just for illustration purposes and not
	part of the protocol definition.		part of the protocol definition.
	To illustrate the behavior when there is a GDR change, consider the		To illustrate the behavior when there is a GDR change, consider the
	following scenario where there are two flows G1 and G2. R1 is the		following scenario where there are two flows G1 and G2. R1 is the
	GDR for G1, and R2 is the GDR for G2. When R3 comes up, it is		GDR for G1, and R2 is the GDR for G2. When R3 comes up, it is
	possible that R3 becomes GDR for both G1 and G2, hence R3 starts to		possible that R3 becomes GDR for both G1 and G2, hence R3 starts to
	build the forwarding tree for G1 and G2. If R1 and R2 stop		build the forwarding tree for G1 and G2. If R1 and R2 stop
	forwarding before R3 completes the process, packet loss might occur.		forwarding before R3 completes the process, packet loss might occur.
	On the other hand, if R1 and R2 continue forwarding while R3 is		On the other hand, if R1 and R2 continue forwarding while R3 is
	building the forwarding trees, duplicates might occur.		building the forwarding trees, duplicates might occur.
	When the role of GDR changes as above, instead of immediately		When the role of GDR changes as above, instead of immediately
	stopping forwarding, R1 and R2 continue forwarding to G1 and G2		stopping forwarding, R1 and R2 continue forwarding to G1 and G2
	respectively, while, at the same time, R3 build forwarding trees for		respectively, while, at the same time, R3 build forwarding trees for
	G1 and G2. This will lead to PIM Asserts.		G1 and G2. This will lead to PIM Asserts.
	Using the above example, for G1, assume R1 and R3 agree on the new		For G1, using the functionality described in this document, R1 and R3
	GDR, which is R3. With the new assert behavior, R1 sets its assert		determine the new GDR, which is R3. With the modified Assert
	metric to the near maximum value discussed above. That will make R3,		behavior, R1 sets its Assert metric to the near maximum value
	which has normal metric in its Assert as the Assert winner.		discussed above. That will make R3, which has normal metric in its
			Assert as the Assert winner.
	For G2, assume it takes a slightly longer time for R2 to find out
	that R3 is the new GDR and still considers itself being the GDR while
	R3 already has assumed the role of GDR. Since both R2 and R3 think
	they are GDRs, they further compare their metric and IP addresses.
	If R3 has the better routing metric, or the same metric but a better
	tie-breaker, the result will be consistent during GDR selection. If
	unfortunately, R2 has the better metric or the same metric but a
	better tie-breaker, R2 will become the Assert winner and continues to
	forward traffic. Shortly after when R2 finds out that it is no
	longer the GDR, R2 will change to using the near maximum assert
	metric. Next time R2 sends an assert message, it will lose the
	assert and stop forwarding. As assert winner, R2 would send periodic
	assert messages per [RFC7761].
	5.8. Backward Compatibility		5.8. Backward Compatibility
	In the case of a hybrid Ethernet shared LAN (where some PIM routers		In the case of a hybrid Ethernet shared LAN (where some PIM routers
	enable the specification defined in this document, and some do not).		support the functionality defined in this document, and some do not);
	o If a router which does not support this specification becomes the		o If the DR does not support the new functionality, then there will
	DR on the LAN, then it is the only router acting as a DR, and		be no load-balancing.
	there will be no load-balancing.
	o If a router which does not support this specification becomes a		o If non-DR routers do not support the new functionality, they will
	non-DR on link, then it acts as non-DR defined in [RFC7761], and		not be considered as Candidate GDRs and it will not take part in
	it will not take part in any load-balancing. Load-balancing may		an load-balancing. Load-balancing may still happen on the link.
	still happen.
	6. Manageability Considerations		6. Operational Considerations
	An administrator needs to consider what the total bandwidth		An administrator needs to consider what the total bandwidth
	requirements are and find a set of routers that together has enough		requirements are and find a set of routers that together has enough
	total capacity, while making sure that each of the router can handle		total capacity, while making sure that each of the routers can handle
	its part, assuming that the traffic is distributed roughly equally		its part, assuming that the traffic is distributed roughly equally
	among the routers. Ideally, one should also have enough bandwidth to		among the routers. Ideally, one should also have enough bandwidth to
	handle the case where at least one router fails. Ideally all the		handle the case where at least one router fails. All routers should
	routers should have reachability to the sources, and RPs if		have reachability to the sources, and RPs if applicable, that is not
	applicable, that is not via the LAN.		via the LAN.
	Care must be taken when choosing what hash masks to configure. One		Care must be taken when choosing what hash masks to configure. One
	would typically configure the same masks on all the routers, so that		would typically configure the same masks on all the routers, so that
	they are the same, regardless of which router is elected as DR. The		they are the same, regardless of which router is elected as DR. The
	default masks are likely suitable for most deployment. The RP Hash		default masks are likely suitable for most deployment. The RP Hash
	Mask must be configured (the default is no bits set) if one wishes to		Mask must be configured (the default is no bits set) if one wishes to
	hash based on the RP address rather than the group address for ASM.		hash based on the RP address rather than the group address for ASM.
	The default masks will use the entire group addresses, and source		The default masks will use the entire group addresses, and source
	addresses if SSM, as part of the hash. An administrator may set		addresses if SSM, as part of the hash. An administrator may set
	other masks that masks out part of the addresses to ensure that		other masks that masks out part of the addresses to ensure that
	skipping to change at page 17, line 19 ¶		skipping to change at page 17, line 11 ¶
	Balancing List (DRLB-List) Hello Option in the PIM-Hello Options		Balancing List (DRLB-List) Hello Option in the PIM-Hello Options
	registry. IANA is requested to make these assignments permanent when		registry. IANA is requested to make these assignments permanent when
	this document is published as an RFC. Note that the option names		this document is published as an RFC. Note that the option names
	have changed slightly since the temporary assignments were made.		have changed slightly since the temporary assignments were made.
	Also, the length of option 34 is always 4, the registry currently		Also, the length of option 34 is always 4, the registry currently
	says it is variable.		says it is variable.
	This document requests IANA to create a registry called "Designated		This document requests IANA to create a registry called "Designated
	Router Load Balancing Hash Algorithms" in the "Protocol Independent		Router Load Balancing Hash Algorithms" in the "Protocol Independent
	Multicast (PIM)" branch of the registry tree. The registry lists		Multicast (PIM)" branch of the registry tree. The registry lists
	hash algorithms for use by PIM Designated Router Load Balancing.		Hash Algorithms for use by PIM Designated Router Load Balancing.
	7.1. Initial registry		7.1. Initial registry
	The initial content of the registry should be as follows.		The initial content of the registry should be as follows.
	Type Name Reference		Type Name Reference
	------ ---------------------------------------- --------------------		------ ---------------------------------------- --------------------
	0 Modulo This document		0 Modulo This document
	1-255 Unassigned		1-255 Unassigned
	7.2. Assignment of new hash algorithms		7.2. Assignment of new Hash Algorithms
	Assignment of new hash algorithms is done according to the "IETF		Assignment of new Hash Algorithms is done according to the "IETF
	Review" model, see [RFC8126].		Review" model, see [RFC8126].
	8. Security Considerations		8. Security Considerations
	Security of the new DR Load Balancing PIM Hello Options is only		Security of the new DR Load Balancing PIM Hello Options is only
	guaranteed by the security of PIM Hello messages, so the security		guaranteed by the security of PIM Hello messages, so the security
	considerations for PIM Hello messages as described in PIM-SM		considerations for PIM Hello messages as described in PIM-SM
	[RFC7761] apply here.		[RFC7761] apply here.
	If the DR is subverted it could omit or add certain GDRs or announce		If the DR is subverted it could omit or add certain GDRs or announce
	an unsupported algorithm. If another router is subverted, it could		an unsupported algorithm. If another router is subverted, it could
	be made DR and cause similar issues. While these issues are specific		be made DR and cause similar issues. While these issues are specific
	to this specification, they are not that different from existing		to this specification, they are not that different from existing
	attacks such as subverting a DR and lowering the DR priority, causing		attacks such as subverting a DR and lowering the DR priority, causing
	a different router to become the DR.		a different router to become the DR.
			If for any reason, the DR includes a GDR in the announced list which
			announces a different algorithm from what the DR announces, the GDR
			is required to ignore the announcement, and there will be no router
			acting as the DR for the flows that hash to that GDR.
	If a GDR is subverted, it could potentially be made to stop		If a GDR is subverted, it could potentially be made to stop
	forwarding all the traffic it is expected to forward. This is also		forwarding all the traffic it is expected to forward. This is also
	similar today to if a DR is subverted.		similar today to if a DR is subverted.
	9. Acknowledgement		9. Acknowledgement
	The authors would like to thank Steve Simlo and Taki Millonis for		The authors would like to thank Steve Simlo and Taki Millonis for
	helping with the original idea; Alia Atlas, Bill Atwood, Jake		helping with the original idea; Alia Atlas, Bill Atwood, Jake
	Holland, Bharat Joshi, Anish Kachinthaya, Anvitha Kachinthaya and		Holland, Bharat Joshi, Anish Kachinthaya, Anvitha Kachinthaya and
	Alvaro Retana for reviews and comments; and Toerless Eckert and		Alvaro Retana for reviews and comments; and Toerless Eckert and
	skipping to change at page 18, line 36 ¶		skipping to change at page 18, line 32 ¶
	[RFC6395] Gulrajani, S. and S. Venaas, "An Interface Identifier (ID)		[RFC6395] Gulrajani, S. and S. Venaas, "An Interface Identifier (ID)
	Hello Option for PIM", RFC 6395, DOI 10.17487/RFC6395,		Hello Option for PIM", RFC 6395, DOI 10.17487/RFC6395,
	October 2011, <https://www.rfc-editor.org/info/rfc6395>.		October 2011, <https://www.rfc-editor.org/info/rfc6395>.
	[RFC7761] Fenner, B., Handley, M., Holbrook, H., Kouvelas, I.,		[RFC7761] Fenner, B., Handley, M., Holbrook, H., Kouvelas, I.,
	Parekh, R., Zhang, Z., and L. Zheng, "Protocol Independent		Parekh, R., Zhang, Z., and L. Zheng, "Protocol Independent
	Multicast - Sparse Mode (PIM-SM): Protocol Specification		Multicast - Sparse Mode (PIM-SM): Protocol Specification
	(Revised)", STD 83, RFC 7761, DOI 10.17487/RFC7761, March		(Revised)", STD 83, RFC 7761, DOI 10.17487/RFC7761, March
	2016, <https://www.rfc-editor.org/info/rfc7761>.		2016, <https://www.rfc-editor.org/info/rfc7761>.
			[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
			Writing an IANA Considerations Section in RFCs", BCP 26,
			RFC 8126, DOI 10.17487/RFC8126, June 2017,
			<https://www.rfc-editor.org/info/rfc8126>.
	[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC		[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
	2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,		2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
	May 2017, <https://www.rfc-editor.org/info/rfc8174>.		May 2017, <https://www.rfc-editor.org/info/rfc8174>.
	10.2. Informative References		10.2. Informative References
	[RFC3376] Cain, B., Deering, S., Kouvelas, I., Fenner, B., and A.		[RFC3376] Cain, B., Deering, S., Kouvelas, I., Fenner, B., and A.
	Thyagarajan, "Internet Group Management Protocol, Version		Thyagarajan, "Internet Group Management Protocol, Version
	3", RFC 3376, DOI 10.17487/RFC3376, October 2002,		3", RFC 3376, DOI 10.17487/RFC3376, October 2002,
	<https://www.rfc-editor.org/info/rfc3376>.		<https://www.rfc-editor.org/info/rfc3376>.
	skipping to change at page 19, line 15 ¶		skipping to change at page 19, line 15 ¶
	[RFC4541] Christensen, M., Kimball, K., and F. Solensky,		[RFC4541] Christensen, M., Kimball, K., and F. Solensky,
	"Considerations for Internet Group Management Protocol		"Considerations for Internet Group Management Protocol
	(IGMP) and Multicast Listener Discovery (MLD) Snooping		(IGMP) and Multicast Listener Discovery (MLD) Snooping
	Switches", RFC 4541, DOI 10.17487/RFC4541, May 2006,		Switches", RFC 4541, DOI 10.17487/RFC4541, May 2006,
	<https://www.rfc-editor.org/info/rfc4541>.		<https://www.rfc-editor.org/info/rfc4541>.
	[RFC4607] Holbrook, H. and B. Cain, "Source-Specific Multicast for		[RFC4607] Holbrook, H. and B. Cain, "Source-Specific Multicast for
	IP", RFC 4607, DOI 10.17487/RFC4607, August 2006,		IP", RFC 4607, DOI 10.17487/RFC4607, August 2006,
	<https://www.rfc-editor.org/info/rfc4607>.		<https://www.rfc-editor.org/info/rfc4607>.
	[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
	Writing an IANA Considerations Section in RFCs", BCP 26,
	RFC 8126, DOI 10.17487/RFC8126, June 2017,
	<https://www.rfc-editor.org/info/rfc8126>.
	Authors' Addresses		Authors' Addresses
	Yiqun Cai		Yiqun Cai
	Alibaba Group		Alibaba Group
	Email: yiqun.cai@alibaba-inc.com		Email: yiqun.cai@alibaba-inc.com
	Heidi Ou		Heidi Ou
	Alibaba Group		Alibaba Group
End of changes. 63 change blocks.
	177 lines changed or deleted		171 lines changed or added
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