rfc9739v3.txt		rfc9739.txt
	skipping to change at line 175 ¶		skipping to change at line 175 ¶
	No other message types are supported by PIM Light; other message		No other message types are supported by PIM Light; other message
	types MUST NOT be processed if received on a PLI.		types MUST NOT be processed if received on a PLI.
	3.2. Considerations for the Absence of Hello Message		3.2. Considerations for the Absence of Hello Message
	Because Hello messages are not processed in a PIM Light domain, the		Because Hello messages are not processed in a PIM Light domain, the
	considerations in the subsections below should be taken into account.		considerations in the subsections below should be taken into account.
	3.2.1. Join Attribute		3.2.1. Join Attribute
	Since a PLI does not process PIM Hello messages, it also does not		Since a PLI does not use PIM Hello messages, it also does not support
	support the Join Attribute option in PIM Hello as specified in		the Join Attribute option in PIM Hello as specified in [RFC5384]. As
	[RFC5384]. As such, PIM Light is unaware of its neighbor's		such, PIM Light is unaware of its neighbor's capability to process
	capability to send Join Attributes and SHOULD NOT process a Join		Join Attributes and SHOULD NOT send a Join message containing a Join
	message containing a Join Attribute.		Attribute.
	There are two cases in which a PLI can send and process a Join		There are two cases in which a PLI can support a Join Attribute:
	Attribute:
	* The Join Attribute must be configured with an appropriate Join		* The neighbors on the PLI are known via configuration to be capable
	Attribute type that the PLI is capable of processing as per the		of processing the attribute.
	"PIM Join Attribute Types" registry [IANA-PIM-Attr-Types].
	* Internet-Drafts and RFCs may dictate that certain join attributes		* Internet-Drafts and RFCs may dictate that certain Join Attributes
	are allowed to be used without explicit configuration of the PLI		are allowed to be used without explicit configuration of the PLI
	in certain scenarios. The details are left to those Internet-		in certain scenarios. The details are left to those Internet-
	Drafts and RFCs.		Drafts and RFCs.
	3.2.2. DR Election		3.2.2. DR Election
	Due to the absence of Hello messages, DR election is not supported on		Due to the absence of Hello messages, DR election is not supported on
	a PIM Light router. The network design must ensure DR election		a PIM Light router. The network design must ensure DR election
	occurs within the PIM domain, assuming the PIM Light domain		occurs within the PIM domain, assuming the PIM Light domain
	interconnects PIM domains.		interconnects PIM domains.
	skipping to change at line 248 ¶		skipping to change at line 246 ¶
	the downstream IBBR identifies two EBBRs, it can select one using a		the downstream IBBR identifies two EBBRs, it can select one using a
	unique IP selection algorithm, such as choosing the EBBR with the		unique IP selection algorithm, such as choosing the EBBR with the
	lowest or highest IP address. If the selected EBBR goes offline, the		lowest or highest IP address. If the selected EBBR goes offline, the
	downstream router can use the next EBBR based on the IP selection		downstream router can use the next EBBR based on the IP selection
	algorithm, which is beyond the scope of this document.		algorithm, which is beyond the scope of this document.
	3.3. PLI Configuration		3.3. PLI Configuration
	Since a PLI doesn't require PIM Hello Messages and PIM neighbor		Since a PLI doesn't require PIM Hello Messages and PIM neighbor
	adjacency is not checked for arriving Join/Prune messages, there		adjacency is not checked for arriving Join/Prune messages, there
	needs to be a mechanism to enable PLIs on interfaces. If a router		needs to be a mechanism to enable PLIs on interfaces. Join/Prune
	supports PIM Light, arriving Join/Prune messages MUST be processed		messages not received from a PIM neighbor MUST be dropped unless PLI
	only when a PLI is enabled on an interface; otherwise, they MUST be		is enabled on the interface. In some cases, a PLI may be enabled
	dropped. In some cases, a PLI may be enabled automatically via an		automatically via an underlying mechanism on a logical interface.
	underlying mechanism on a logical interface. For example, in a BIER		For example, in a BIER domain, a logical interface can connect two or
	domain, a logical interface can connect two or more BIER edge routers		more BIER edge routers as per [BIER-PIM]).
	as per [BIER-PIM]).
	3.4. Failures in PLR Domain		3.4. Failures in PLR Domain
	Because Hello messages are not processed on the PLI, PLI failures may		Because Hello messages are not processed on the PLI, PLI failures may
	not be discovered in a PIM Light domain, and multicast routes will		not be discovered in a PIM Light domain, and multicast routes will
	not be pruned toward the source on the PIM Light domain. This		not be pruned toward the source on the PIM Light domain. This
	results in the upstream routers continuously sending multicast		results in the upstream routers continuously sending multicast
	streams until the outgoing interface (OIF) expires.		streams until the outgoing interface (OIF) expires.
	Other protocols can be used to detect these failures in the PIM Light		Other protocols can be used to detect these failures in the PIM Light
	skipping to change at line 354 ¶		skipping to change at line 351 ¶
	not process Hello or Assert messages. In addition, as detailed in		not process Hello or Assert messages. In addition, as detailed in
	Section 6.3 of [RFC7761], the authentication mechanisms described in		Section 6.3 of [RFC7761], the authentication mechanisms described in
	[RFC5796] can be applied to PIM Light via IPsec Encapsulating		[RFC5796] can be applied to PIM Light via IPsec Encapsulating
	Security Payload (ESP) or, optionally, the Authentication Header		Security Payload (ESP) or, optionally, the Authentication Header
	(AH).		(AH).
	6. References		6. References
	6.1. Normative References		6.1. Normative References
	[IANA-PIM-Attr-Types]
	IANA, "PIM Join Attribute Types",
	<https://www.iana.org/assignments/pim-parameters>.
	[IANA-PIM-Mess-Types]		[IANA-PIM-Mess-Types]
	IANA, "PIM Message Types",		IANA, "PIM Message Types",
	<https://www.iana.org/assignments/pim-parameters>.		<https://www.iana.org/assignments/pim-parameters>.
	[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>.
	[RFC4607] Holbrook, H. and B. Cain, "Source-Specific Multicast for		[RFC4607] Holbrook, H. and B. Cain, "Source-Specific Multicast for
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