Diff: rfc9705xml2.original.xml

	rfc9705xml2.original.xml	rfc9705.xml

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	.8126.xml">
	]>	]>

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	<rfc category="std" docName="draft-ietf-mpls-ri-rsvp-frr-22" ipr="pre5378Trust20
	0902" submissionType="IETF" consensus="true" updates="4090">
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	<!-- *** FRONT MATTER *** -->	<rfc xmlns:xi="http://www.w3.org/2001/XInclude" category="std" docName="draft-ie tf-mpls-ri-rsvp-frr-22" number="9705" ipr="pre5378Trust200902" submissionType="I ETF" consensus="true" obsoletes="" updates="4090" tocInclude="true" tocDepth="4" symRefs="true" sortRefs="true" version="3" xml:lang="en" >

	<front>	<front>

	<!-- The abbreviated title is used in the page header - it is only necessary	<title abbrev="RI-RSVP-FRR Bypass">Refresh-Interval Independent RSVP Fast Rer
	if the	oute Facility Protection</title>
	full title is longer than 39 characters -->	<seriesInfo name="RFC" value="9705"/>
		<author initials="C." surname="Ramachandran" fullname="Chandra Ramachandran"
	<title abbrev="RI-RSVP FRR Bypass">Refresh-interval Independent FRR Facility	>
	Protection	<organization>Juniper Networks, Inc.</organization>
	</title>	<address>
		<email>csekar@juniper.net</email>
	<!-- add 'role="editor"' below for the editors if appropriate -->	</address>

	<!-- Another author who claims to be an editor -->

	<author initials="C. " surname="Ramachandran" fullname="Chandra Ramachandran
	">
	<organization>Juniper Networks, Inc.</organization>
	<address>
	<email>csekar@juniper.net</email>
	</address>
	</author>	</author>

		<author initials="T." surname="Saad" fullname="Tarek Saad">
	<author initials="T. " surname="Saad" fullname="Tarek Saad">	<organization>Cisco Systems, Inc.</organization>
	<organization>Cisco Systems, Inc.</organization>	<address>
	<address>	<email>tsaad@cisco.com</email>
	<email>tsaad@cisco.com</email>	</address>
	</address>
	</author>	</author>

		<author initials="I." surname="Minei" fullname="Ina Minei">
	<author initials="I. " surname="Minei" fullname="Ina Minei">	<organization>Google, Inc.</organization>
	<organization>Google, Inc.</organization>	<address>
	<address>	<email>inaminei@google.com</email>
	<email>inaminei@google.com</email>	</address>
	</address>
	</author>	</author>

		<author initials="D." surname="Pacella" fullname="Dante Pacella">
	<author initials="D. " surname="Pacella" fullname="Dante Pacella">	<organization>Verizon, Inc.</organization>
	<organization>Verizon, Inc.</organization>	<address>
	<address>	<email>dante.j.pacella@verizon.com</email>
	<email>dante.j.pacella@verizon.com</email>	</address>
	</address>
	</author>	</author>

		<date year="2025" month="January"/>


	<date year="2024" />	<area>RTG</area>
		<workgroup>mpls</workgroup>
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	<!-- Meta-data Declarations -->

	<area>Routing</area>

	<workgroup>MPLS Working Group</workgroup>

	<!-- WG name at the upperleft corner of the doc,
	IETF is fine for individual submissions.
	If this element is not present, the default is "Network Working Group",
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	<keyword>template</keyword>

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	<abstract>	<abstract>

		<t>The RSVP-TE Fast Reroute (FRR) extensions specified in RFC 4090
		define two local repair techniques to reroute Label Switched Path (LSP)
		traffic over pre-established backup tunnels. Facility backup method
		allows one or more LSPs traversing a connected link or node to be
		protected using a bypass tunnel. The many-to-one nature of local repair
		technique is attractive from a scalability point of view. This document
		enumerates facility backup procedures in RFC 4090 that rely on refresh
		timeout, hence, making facility backup method refresh-interval
		dependent. The RSVP-TE extensions defined in this document will enhance
		the facility backup protection mechanism by making the corresponding
		procedures refresh-interval independent, and hence, compatible with the
		Refresh-Interval Independent RSVP (RI-RSVP) capability specified in RFC
		8370. Hence, this document updates RFC 4090 in order to support the
		RI-RSVP capability specified in RFC 8370.
		</t>
		</abstract>
		</front>


	<t>The RSVP-TE Fast Reroute extensions specified in RFC 4090 defines two local	<middle>
	repair techniques to reroute Label Switched Path (LSP) traffic over	<section anchor="intro">
	pre-established backup tunnel. Facility backup method allows one or more	<name>Introduction</name>
	LSPs traversing a connected link or node to be protected using a bypass	<t>RSVP-TE relies on a periodic refresh of RSVP messages to synchronize
	tunnel. The many-to-one nature of local repair technique is attractive	and maintain the states related to the Label Switched Path (LSP) along the
	from scalability point of view. This document enumerates facility backup	reserved path. In the absence of refresh messages, the LSP-related
	procedures in RFC 4090 that rely on refresh timeout and hence make	states are automatically deleted. Reliance on periodic refreshes and
	facility backup method refresh-interval dependent. The RSVP-TE extensions	refresh timeouts are problematic from the scalability point of view. The
	defined in this document will enhance the facility backup protection	number of RSVP-TE LSPs that a router needs to maintain has been growing
	mechanism by making the corresponding procedures refresh-interval	in service provider networks, and the implementations should be capable
	independent and hence compatible with Refresh-interval Independent RSVP	of handling increases in LSP scale.
	(RI-RSVP) specified in RFC 8370. Hence, this document updates RFC 4090 in
	order to support RI-RSVP capability specified in RFC 8370.
	</t>

	</abstract>

	<note title="Requirements Language">

	<t>The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIO
	NAL" in this
	document are to be interpreted as described in BCP 14 <xref target="RFC2119
	"/>
	<xref target="RFC8174"/> when, and only when, they
	appear in all capitals, as shown here.
	</t>
	</note>

	</front>

	<middle>
	<section anchor="intro" title="Introduction">

	<t>RSVP-TE relies on periodic refresh of RSVP messages to synchronize and
	maintain the Label Switched Path (LSP) related states along the reserved
	path. In the absence of refresh messages, the LSP-related states are
	automatically deleted. Reliance on periodic refreshes and refresh timeouts
	are problematic from the scalability point of view. The number of RSVP-TE
	LSPs that a router needs to maintain has been growing in service provider
	networks and the implementations should be capable of handling increase in
	LSP scale.
	</t>

	<t><xref target="RFC2961"/> specifies mechanisms to eliminate the reliance
	on periodic
	refresh and refresh timeout of RSVP messages and enables a router to
	increase the message refresh interval to values much longer than the
	default 30 seconds defined in <xref target="RFC2205"/>. However, the protoc
	ol extensions
	defined in <xref target="RFC4090"/> for supporting Fast Reroute (FRR) using
	bypass tunnels
	implicitly rely on short refresh timeouts to cleanup stale states.
	</t>

	<t>In order to eliminate the reliance on refresh timeouts, the routers
	should unambiguously determine when a particular LSP state should be
	deleted. In scenarios involving <xref target="RFC4090"/> FRR using bypass t
	unnels,
	additional explicit tear down messages are necessary. Refresh-interval
	Independent RSVP FRR (RI-RSVP-FRR) extensions specified in this document
	consists of procedures to enable LSP state cleanup that are essential in
	supporting RI-RSVP capability for <xref target="RFC4090"/> FRR using bypass
	tunnels.
	</t>

	<section anchor="intro_motivation" title="Motivation">
	<t>Base RSVP <xref target="RFC2205"/> maintains state via the
	generation of RSVP Path/Resv refresh messages. Refresh messages are used
	to both synchronize state between RSVP neighbors and to recover from lost
	RSVP messages. The use of Refresh messages to cover many possible
	failures has resulted in a number of operational problems.

	<list style="hanging">
	<t hangText="-">One problem relates to RSVP control plane scaling due to
	periodic refreshes of Path and Resv messages, another
	relates to the reliability and latency of RSVP signaling.
	</t>	</t>

	</list>	<t><xref target="RFC2961"/> specifies mechanisms to eliminate the
	<list style="hanging">	reliance on periodic refreshes and refresh timeouts of RSVP messages and
	<t hangText="-">An additional problem is the time to clean up the stale	enables a router to increase the message refresh interval to values much
	state after a tear message is lost. For more on these	longer than the default 30 seconds defined in <xref
	problems see Section 1 of RSVP Refresh Overhead Reduction	target="RFC2205"/>. However, the protocol extensions defined in <xref
	Extensions <xref target="RFC2961"/>.	target="RFC4090"/> for supporting Fast Reroute (FRR) using bypass
		tunnels implicitly rely on short refresh timeouts to clean up stale
		states.
	</t>	</t>

	</list>	<t>In order to eliminate the reliance on refresh timeouts, the routers
	</t>	should unambiguously determine when a particular LSP state should be
		deleted. In scenarios involving FRR using bypass tunnels <xref
		target="RFC4090"/>, additional explicit teardown messages are
		necessary. The Refresh-Interval Independent RSVP-TE FRR (RI-RSVP-FRR)
		extensions specified in this document consist of procedures to enable
		LSP state cleanup that are essential in supporting the RI-RSVP capability
		for FRR using bypass tunnels from <xref target="RFC4090"/>.
		</t>
		<section anchor="intro_motivation">
		<name>Motivation</name>


	<t>The problems listed above adversely affect RSVP control plane	<t>Base RSVP <xref target="RFC2205"/> maintains state via the
	scalability and RSVP-TE <xref target="RFC3209"/> inherited these problems	generation of RSVP Path and Resv refresh messages. Refresh messages are
	from standard RSVP. Procedures specified in <xref target="RFC2961"/>	used to both synchronize state between RSVP neighbors and to recover
	address the above-mentioned problems by eliminating dependency on	from lost RSVP messages. The use of Refresh messages to cover many
	refreshes for state synchronization and for recovering from lost RSVP	possible failures has resulted in a number of operational problems.
	messages, and by eliminating dependency on refresh timeout for stale	</t>
	state cleanup. Implementing these procedures allows implementations to	<ul>
	improve RSVP-TE control plane scalability. For more details on	<li>One problem relates to RSVP control plane scaling due to
	eliminating dependency on refresh timeout for stale state cleanup, refer	periodic refreshes of Path and Resv messages.</li>
	to "Refresh-interval Independent RSVP" section 3 of RSVP-TE Scaling	<li>Another problem relates to the
	Techniques <xref target="RFC8370"/>.	reliability and latency of RSVP signaling.</li>
	</t>	<li>An additional problem is the time to clean up the stale state
		after a tear message is lost. For more on these problems, see <xref
		target="RFC2961" sectionFormat="of" section="1"/>.</li>
		</ul>


	<t>However, the facility backup protection procedures specified in	<t>The problems listed above adversely affect RSVP control plane
		scalability, and RSVP-TE <xref target="RFC3209"/> inherited these
		problems from standard RSVP. Procedures specified in <xref
		target="RFC2961"/> address the above-mentioned problems by eliminating
		dependency on refreshes for state synchronization and for recovering
		from lost RSVP messages, and also by eliminating dependency on refresh
		timeout for stale state cleanup. Implementing these procedures allows
		implementations to improve RSVP-TE control plane scalability. For more
		details on eliminating dependency on refresh timeouts for stale state
		cleanup, refer to <xref target="RFC8370" sectionFormat="of"
		section="3"/>.
		</t>

		<t>However, the facility backup protection procedures specified in
	<xref target="RFC4090"/> do not fully address stale state cleanup as the	<xref target="RFC4090"/> do not fully address stale state cleanup as the
	procedures depend on refresh timeouts for stale state cleanup. The	procedures depend on refresh timeouts for stale state cleanup. The
	updated facility backup protection procedures specified in this document,	updated facility backup protection procedures specified in this document,
	in combination with RSVP-TE Scaling Techniques <xref target="RFC8370"/>,	in combination with RSVP-TE Scaling Techniques <xref target="RFC8370"/>,
	eliminate this dependency on refresh timeouts for stale state cleanup.	eliminate this dependency on refresh timeouts for stale state cleanup.
	</t>	</t>


	<t>The procedures specified in this document assume reliable delivery of	<t>The procedures specified in this document assume reliable delivery of
	RSVP messages, as specified in <xref target="RFC2961"/>. Therefore, this	RSVP messages, as specified in <xref target="RFC2961"/>. Therefore, <xref t
	document makes support for <xref target="RFC2961"/> a pre-requisite.	arget="RFC2961"/> is a prerequisite for this
	</t>	document.
		</t>
		</section>
	</section>	</section>

	</section>

	<section anchor="terminology" title="Terminology">

	<t>The reader is expected to be familiar with the terminology in
	<xref target="RFC2205"/>, <xref target="RFC3209"/>,
	<xref target="RFC4090"/>, <xref target="RFC4558"/>,
	<xref target="RFC8370"/> and <xref target="RFC8796"/>.
	</t>

	<t>Phop node: Previous-hop router along the label switched path
	</t>

	<t>PPhop node: Previous-Previous-hop router along the label switched path
	</t>

	<t>Nhop node: Next-hop router along the label switched path
	</t>

	<t>NNhop node: Next-Next-hop router along the label switched path
	</t>

	<t>PLR: Point of Local Repair router as defined in <xref target="RFC4090"/>
	</t>

	<t>MP: Merge Point router as defined in <xref target="RFC4090"/>
	</t>

	<t>LP-MP node: Merge Point router at the tail of Link-Protecting bypass tun
	nel
	</t>

	<t>NP-MP node: Merge Point router at the tail of Node-Protecting bypass tun
	nel
	</t>

	<t>RRO: Record Route Object as defined in <xref target="RFC3209"/>
	</t>

	<t>TED: Traffic Engineering Database
	</t>

	<t>LSP state: The combination of "path state" maintained as Path State Bloc
	k
	(PSB) and "reservation state" maintained as Reservation State Block (RSB)
	forms an individual LSP state on an RSVP-TE speaker
	</t>

	<t>RI-RSVP: The set of procedures defined in Section 3 of RSVP-TE Scaling
	Techniques <xref target="RFC8370"/> to eliminate RSVP's reliance on periodi
	c
	message refreshes
	</t>

	<t>B-SFRR-Ready: Bypass Summary FRR Ready Extended Association object defin
	ed
	in Summary FRR extensions <xref target="RFC8796"/> and is added by the PLR
	for each protected LSP.
	</t>

	<t>RI-RSVP-FRR: The set of procedures defined in this document to eliminate
	RSVP's reliance of periodic message refreshes when supporting facility back
	up
	protection <xref target="RFC4090"/>
	</t>

	<t>Conditional PathTear: A PathTear message containing a suggestion to a
	receiving downstream router to retain the path state if the receiving route
	r
	is an NP-MP
	</t>


	<t>Remote PathTear: A PathTear message sent from a Point of Local Repair (P	<section anchor="terms-abbrevs">
	LR)	<name>Abbreviations and Terminology</name>
	to the MP to delete the LSP state on the MP if PLR had not previously sent	<t>
	the	The key words "<bcp14>MUST</bcp14>", "<bcp14>MUST NOT</bcp14>",
	backup Path state reliably	"<bcp14>REQUIRED</bcp14>", "<bcp14>SHALL</bcp14>", "<bcp14>SHALL NOT</bcp14>
	</t>	",
	</section>	"<bcp14>SHOULD</bcp14>", "<bcp14>SHOULD NOT</bcp14>",
		"<bcp14>RECOMMENDED</bcp14>", "<bcp14>NOT RECOMMENDED</bcp14>",
	<section anchor="prob_desc" title="Problem Description">	"<bcp14>MAY</bcp14>", and "<bcp14>OPTIONAL</bcp14>" in this document are to
		be
		interpreted as described in BCP 14 <xref target="RFC2119"/> <xref
		target="RFC8174"/> when, and only when, they appear in all capitals, as
		shown here.
		</t>
		<t>
		In addition, the reader is expected to be familiar with the terminology
		in <xref
		target="RFC2205"/>, <xref target="RFC3209"/>, <xref
		target="RFC4090"/>, <xref target="RFC4558"/>, <xref
		target="RFC8370"/>, and <xref target="RFC8796"/>.
		</t>


	<figure align="center" anchor="example_network" title="Example Topology">	<section anchor="abbrevs">
	<artwork align="center"><![CDATA[	<name>Abbreviations</name>
		<dl>
		<dt>PHOP:</dt><dd>Previous-Hop (can refer to a router or node along the L
		SP)</dd>
		<dt>PPHOP:</dt><dd>Previous-Previous-Hop (can refer to a router or node a
		long the LSP)</dd>
		<dt>NHOP:</dt><dd>Next-Hop (can refer to a router or node along the LSP)<
		/dd>
		<dt>NNHOP:</dt><dd>Next-Next-Hop (can refer to a router or node along the
		LSP)</dd>
		<dt>PLR:</dt><dd>Point of Local Repair (can refer to a router as defined
		in <xref target="RFC4090"/>)</dd>
		<dt>MP:</dt><dd>Merge Point (can refer to a router as defined in <xref ta
		rget="RFC4090"/>)</dd>
		<dt>LP-MP:</dt><dd>Link-Protecting Merge Point (can refer to a router or
		node at the tail of a Link-Protecting bypass tunnel</dd>
		<dt>NP-MP:</dt><dd>Node-Protecting Merge Point (can refer to a router or
		node at the tail of a Node-Protecting bypass tunnel</dd>
		<dt>PSB:</dt><dd>Path State Block</dd>
		<dt>RSB:</dt><dd>Reservation State Block</dd>
		<dt>RRO:</dt><dd>Record Route Object (as defined in <xref target="RFC3209
		"/>)</dd>
		<dt>TED:</dt><dd>Traffic Engineering Database</dd>
		<dt>RI-RSVP:</dt><dd>Refresh-Interval Independent RSVP (the set of proced
		ures defined in <xref section="3" sectionFormat="of" target="RFC8370"/> to elimi
		nate RSVP's reliance on periodic
		message refreshes)</dd>
		<dt>RI-RSVP-FRR:</dt><dd>Refresh-Interval Independent RSVP-TE FRR (the se
		t of procedures defined in this document to eliminate
		RSVP's reliance on periodic message refreshes when supporting facility ba
		ckup
		protection <xref target="RFC4090"/>)</dd>
		</dl>
		</section>
		<section anchor="terms">
		<name>Terminology</name>
		<dl>
		<dt>B-SFRR-Ready:</dt><dd>Bypass Summary FRR Ready Extended ASSOCIATION o
		bject as defined
		in <xref target="RFC8796"/> and added by the PLR
		for each protected LSP</dd>
		<dt>Conditional PathTear:</dt><dd>A PathTear message containing a suggest
		ion to a
		receiving downstream router to retain the path state if the receiving rou
		ter
		is an NP-MP</dd>
		<dt>Remote PathTear:</dt><dd>A PathTear message sent from a PLR
		to the MP to delete the LSP state on the MP if the PLR had not previously
		sent the
		backup path state reliably</dd>
		<dt>LSP state</dt><dd>The combination of "path state" maintained as a PSB
		and
		"reservation state" maintained as an RSB forms an individual LSP state o
		n an
		RSVP-TE speaker</dd>
		</dl>
		</section>
		</section>
		<section anchor="prob_desc">
		<name>Problem Description</name>
		<figure anchor="example_network">
		<name>Example Topology</name>
		<artwork align="center"><![CDATA[
	E	E
	/ \	/ \
	/ \	/ \
	/ \	/ \
	/ \	/ \
	/ \	/ \
	/ \	/ \
	A ----- B ----- C ----- D	A ----- B ----- C ----- D
	\ /	\ /
	\ /	\ /
	\ /	\ /
	\ /	\ /
	\ /	\ /
	\ /	\ /
	F	F

	]]></artwork>	]]></artwork>
		</figure>
	</figure>


	<t>In the topology in <xref target="example_network"/>, consider a	<t>In the topology in <xref target="example_network"/>, consider a
	large number of LSPs from A to D transiting B and C. Assume that refresh	large number of LSPs from A to D transiting B and C. Assume that refresh

	interval has been configured to be long of the order of minutes and	interval has been configured to be as long as the order of minutes and
	refresh reduction extensions are enabled on all routers.	that refresh reduction extensions are enabled on all routers.
	</t>	</t>
		<t>In addition, assume that node protection has been configured for the LS
	<t>Also assume that node protection has been configured for the LSPs	Ps
	and the LSPs are protected by each router in the following way	and the LSPs are protected by each router in the following way:
		</t>
	<list style="hanging">	<ul>
	<t hangText="-">A has made node protection available using bypass LSP	<li>A has made node protection available using bypass LSP A -> E
	A -> E -> C; A is the PLR and C is the NP-MP	-> C; A is the PLR and C is the NP-MP.</li>
	</t>	<li>B has made node protection available using bypass LSP B -> F
	</list>	-> D; B is the PLR and D is the NP-MP.</li>
	<list style="hanging">	<li>C has made link protection available using bypass LSP C -> B
	<t hangText="-">B has made node protection available using bypass LSP	-> F -> D; C is the PLR and D is the LP-MP.</li>
	B -> F -> D; B is the PLR and D is the NP-MP	</ul>
	</t>
	</list>
	<list style="hanging">
	<t hangText="-">C has made link protection available using bypass LSP
	C -> B -> F -> D; C is the PLR and D is the LP-MP
	</t>
	</list>
	</t>


	<t>In the above condition, assume that B-C link fails. The following is	<t>
		In the above condition, assume that the B-C link fails. The following is
	the sequence of events that is expected to occur for all protected	the sequence of events that is expected to occur for all protected
	LSPs under normal conditions.	LSPs under normal conditions.

		</t>


	<list style="hanging">	<ol type="Step %d.">
	<t hangText="1.">B performs local repair and re-directs LSP traffic	<li anchor="step1">B performs a local repair and redirects LSP traffic o
	over the bypass LSP B -> F -> D.	ver the bypass
	</t>	LSP B -> F -> D.</li>
	</list>	<li anchor="step2">B also creates a backup state for the LSP and triggers
	<list style="hanging">	the sending of
	<t hangText="2.">B also creates backup state for the LSP and triggers	a backup LSP state to D over the bypass LSP B -> F -> D.</li>
	sending of backup LSP state to D over the bypass LSP	<li anchor="step3">D receives the backup LSP states and merges the backup
	B -> F -> D.	s with the
	</t>	protected LSPs.</li>
	</list>	<li anchor="step4">As the link on C, over which the LSP states are refre
	<list style="hanging">	shed, has
	<t hangText="3.">D receives backup LSP states and merges the backups	failed, C will no longer receive state refreshes. Consequently, the
	with the protected LSPs.	protected LSP states on C will time out and C will send the teardown
	</t>	messages for all LSPs. As each router should consider itself as an MP,
	</list>	C will time out the state only after waiting for an additional
	<list style="hanging">	duration equal to the refresh timeout.</li>
	<t hangText="4.">As the link on C, over which the LSP states are	</ol>
	refreshed, has failed, C will no longer receive state
	refreshes. Consequently, the protected LSP states on
	C will time out and C will send the tear down messages
	for all LSPs. As each router should consider itself
	as an MP, C will time out the state only after waiting
	for an additional duration equal to refresh timeout.
	</t>
	</list>
	</t>


	<t>While the above sequence of events has been described in <xref target= "RFC4090"/>,	<t>While the above sequence of events has been described in <xref target=" RFC4090"/>,
	there are a few problems for which no mechanism has been specified	there are a few problems for which no mechanism has been specified

	explicitly.	explicitly:
		</t>


	<list style="hanging">	<ul>
	<t hangText="-">If the protected LSP on C times out before D receives	<li>If the protected LSP on C times out before D receives signaling
	signaling for the backup LSP, then D would receive a	for the backup LSP, then D would receive a PathTear from C prior to
	PathTear from C prior to receiving signaling for the	receiving signaling for the backup LSP, thus resulting in deleting the
	backup LSP, thus resulting in deleting the LSP state.	LSP state. This would be possible at scale even with the default refres
	This would be possible at scale even with default	h
	refresh time.	time.</li>
	</t>
	</list>
	<list style="hanging">
	<t hangText="-">If upon the link failure C is to keep state until its
	timeout, then with long refresh interval this may
	result in a large amount of stale state on C.
	Alternatively, if upon the link failure C is to delete
	the state and send a PathTear to D, this would result
	in deleting the state on D, thus deleting the LSP. D
	needs a reliable mechanism to determine whether it is
	an MP or not to overcome this problem.
	</t>
	</list>
	<list style="hanging">
	<t hangText="-">If head-end A attempts to tear down LSP after step 1
	but before step 2 of the above sequence, then B may
	receive the tear down message before step 2 and
	delete the LSP state from its state database. If B
	deletes its state without informing D, with long
	refresh interval this could cause (large) buildup of
	stale state on D.
	</t>
	</list>
	<list style="hanging">
	<t hangText="-">If B fails to perform local repair in step 1, then B
	will delete the LSP state from its state database
	without informing D. As B deletes its state without
	informing D, with long refresh interval this could
	cause (large) buildup of stale state on D.
	</t>
	</list>
	</t>


	<t>The purpose of this document is to provide solutions to the above	<li>If C is to keep state until its timeout upon the link failure,
	problems which will then make it practical to scale up to a large	then with a long refresh interval, this may result in a large amount
	number of protected LSPs in the network.	of stale state on C. Alternatively, if C is to
	</t>	delete the state and send a PathTear to D upon the link failure, then th
		is would result in
		deleting the state on D, thus deleting the LSP. D needs a reliable
		mechanism to determine whether or not it is an MP to overcome this
		problem.</li>


		<li>If head-end A attempts to tear down the LSP after <xref target="step1
		"
		format="none">Step 1</xref> but before <xref target="step2"
		format="none">Step 2</xref> of the above sequence, then B may receive
		the teardown message before <xref target="step2" format="none">Step
		2</xref> and delete the LSP state from its state database. If B
		deletes its state without informing D, with a long refresh interval, this
		could cause a (large) buildup of stale state on D.</li>

		<li>If B fails to perform a local repair in <xref target="step1" format=
		"none">Step 1</xref>, then B will delete
		the LSP state from its state database without informing D. As B
		deletes its state without informing D, with a long refresh interval, thi
		s
		could cause a (large) buildup of stale state on D.</li>
		</ul>

		<t>The purpose of this document is to provide solutions to the above
		problems, which will then make it practical to scale up to a large
		number of protected LSPs in the network.
		</t>
	</section>	</section>


	<section anchor="solution" title="Solution Aspects">	<section anchor="solution">
	<t>The solution consists of five parts.	<name>Solution Aspects</name>
		<t>The solution consists of five parts:</t>
		<ol>
		<li>Utilize the MP determination mechanism specified in RSVP-TE Summary
		FRR <xref target="RFC8796"/> that enables the PLR to signal the
		availability of local protection to the MP. In addition, introduce PLR
		and MP procedures to establish a Node-ID-based Hello session between the
		PLR and the MP to detect router failures and to determine capability.
		See <xref target="sig_handshake"/> of this document for more
		details. This part of the solution reuses some of the extensions
		defined in <xref target="RFC8796"/> and <xref target="RFC8370"/>, and th
		e subsequent
		subsections will list the extensions in these documents that are
		utilized in this document.</li>


	<list style="hanging">	<li>Handle upstream link or node failures by cleaning up LSP states if
	<t hangText="-">Utilize MP determination mechanism specified in	the node has not found itself as an MP through the MP determination
	RSVP-TE Summary FRR <xref target="RFC8796"/> that enables	mechanism. See <xref target="failures"/> of this document for more
	the PLR to signal the availability of local protection to	details.</li>
	the MP. In addition, introduce PLR and MP procedures to
	establish Node-ID based hello session between the PLR and
	the MP to detect router failures and to determine capability.
	See <xref target="sig_handshake"/> of this document for more det
	ails. This part of the solution
	re-uses some of the extensions defined in
	RSVP-TE Summary FRR <xref target="RFC8796"/>
	and RSVP-TE Scaling Techniques <xref target="RFC8370"/>, and
	the subsequent sub-sections will list the extensions in these
	drafts that are utilized in this document.
	</t>
	</list>
	<list style="hanging">
	<t hangText="-">Handle upstream link or node failures by cleaning up
	LSP states if the node has not found itself as an MP through the
	MP determination mechanism. See <xref target="failures"/> of thi
	s document for more details.
	</t>
	</list>
	<list style="hanging">
	<t hangText="-">Introduce extensions to enable a router to send a tear
	down message to the downstream router that enables the
	receiving router to conditionally delete its local LSP state.
	See <xref target="cnd_path_tear"/> of this document for more det
	ails.
	</t>
	</list>
	<list style="hanging">
	<t hangText="-">Enhance facility backup protection by allowing a PLR to
	directly send a tear down message to the MP without requiring
	the PLR to either have a working bypass LSP or have already
	signaled backup LSP state. See <xref target="rem_tear"/> of this
	document for more details.
	</t>
	</list>
	<list style="hanging">
	<t hangText="-">Introduce extensions to enable the above procedures
	to be backward compatible with routers along the LSP path
	running implementation that do not support these procedures.
	See <xref target="compatible"/> of this document for more detail
	s.
	</t>
	</list>
	</t>


	<section anchor="adv_capability" title="Requirement on RFC 4090 Capable Node	<li>Introduce extensions to enable a router to send a teardown
	to advertise RI-RSVP Capability">	message to the downstream router that enables the receiving router to
	<t>A node supporting facility backup protection <xref target="RFC4090"/>	conditionally delete its local LSP state. See <xref
	MUST NOT set the RI-RSVP flag (I bit) that is defined in Section 3.1 of	target="cnd_path_tear"/> of this document for more details.</li>
	RSVP-TE Scaling Techniques <xref target="RFC8370"/> unless it
	supports all the extensions specified in the rest of this document.
	Hence, this document updates <xref target="RFC4090"/> by defining exten
	sions and
	additional procedures over facility backup protection
	<xref target="RFC4090"/> in order to advertise RI-RSVP capability
	<xref target="RFC8370"/>. However, if a node supporting facility
	backup protection <xref target="RFC4090"/> does set the RI-RSVP
	capability (I bit) but does not support all the extensions specified
	in the rest of this document, then it may result in lingering stale sta
	tes
	due to the long refresh intervals recommended by <xref target="RFC8370"
	/>.
	This can also disrupt normal Fast Reroute (FRR) operation.
	<xref target="cap_bit_without_support"/> of this document delves on thi
	s in detail.
	</t>
	</section>


	<section anchor="sig_handshake" title="Signaling Handshake between PLR and M	<li>Enhance facility backup protection by allowing a PLR to directly
	P">	send a teardown message to the MP without requiring the PLR to either
	<section anchor="sig_plr_behavior" title="PLR Behavior">	have a working bypass LSP or have already signaled the backup LSP
	<t>As per the facility backup procedures <xref target="RFC4090"/>, when	state. See <xref target="rem_tear"/> of this document for more
		details.</li>

		<li>Introduce extensions to enable the above procedures to be backward
		compatible with routers along the LSP running implementations that
		do not support these procedures. See <xref target="compatible"/> of
		this document for more details.</li>
		</ol>

		<section anchor="adv_capability">
		<name>Requirement for RFC 4090 Capable Nodes to Advertise the RI-RSVP Ca
		pability</name>
		<t>A node supporting facility backup protection <xref
		target="RFC4090"/> <bcp14>MUST NOT</bcp14> set the RI-RSVP flag (I-bit)
		that is defined in <xref target="RFC8370"
		sectionFormat="of" section="3.1"/> unless it supports all the extensions
		specified in the rest of this document. Hence, this document updates
		<xref target="RFC4090"/> by defining extensions and additional
		procedures over facility backup protection <xref target="RFC4090"/> in
		order to advertise the RI-RSVP capability <xref
		target="RFC8370"/>. However, if a node supporting facility backup
		protection <xref target="RFC4090"/> does set the RI-RSVP capability (I-b
		it) but does not support all the extensions specified in the rest of
		this document, then it may result in lingering stale states due to the
		long refresh intervals recommended by <xref target="RFC8370"/>. This
		can also disrupt normal Fast Reroute (FRR) operations. <xref
		target="cap_bit_without_support"/> of this document delves into this in
		detail.
		</t>
		</section>
		<section anchor="sig_handshake">
		<name>Signaling Handshake Between PLR and MP</name>
		<section anchor="sig_plr_behavior">
		<name>PLR Behavior</name>
		<t>As per the facility backup procedures <xref target="RFC4090"/>, whe
		n
	an LSP becomes operational on a node and the "local protection desire d"	an LSP becomes operational on a node and the "local protection desire d"
	flag has been set in the SESSION_ATTRIBUTE object carried in the Path	flag has been set in the SESSION_ATTRIBUTE object carried in the Path
	message corresponding to the LSP, then the node attempts to make loca l	message corresponding to the LSP, then the node attempts to make loca l
	protection available for the LSP.	protection available for the LSP.

		</t>
		<ul>
		<li>If the "node protection desired" flag is set, then the node
		tries to become a PLR by attempting to create an NP-bypass LSP to
		the NNHOP node avoiding the NHOP node on a protected LSP. In
		case node protection could not be made available, the node
		attempts to create an LP-bypass LSP to the NHOP node avoiding only
		the link that the protected LSP takes to reach the NHOP.</li>
		<li>If the "node protection desired" flag is not set, then the PLR
		attempts to create an LP-bypass LSP to the NHOP node avoiding the
		link that the protected LSP takes to reach the NHOP.</li>
		</ul>


	<list style="hanging">	<t>With regard to the PLR procedures described above and specified
	<t hangText="-">If the "node protection desired" flag is set, then	in <xref target="RFC4090"/>, this document specifies the following
	the node tries to become a PLR by attempting to create a	additional procedures to support RI-RSVP <xref
	NP-bypass LSP to the NNhop node avoiding the Nhop node on	target="RFC8370"/>.</t>
	protected LSP path. In case node protection could not be
	made available, the node attempts to create an LP-bypass LSP
	to the Nhop node avoiding only the link that the protected LSP
	takes to reach the Nhop
	</t>
	</list>
	<list style="hanging">
	<t hangText="-">If the "node protection desired" flag is not set, then
	the PLR attempts to create an LP-bypass LSP to the Nhop node
	avoiding the link that the protected LSP takes to reach the Nho
	p
	</t>
	</list>
	</t>

	<t>With regard to the PLR procedures described above and that are
	specified in <xref target="RFC4090"/>, this document specifies the fo
	llowing
	additional procedures to support RI-RSVP <xref target="RFC8370"/>.


	<list style="hanging">	<ul>
	<t hangText="-">While selecting the destination address of the bypass	<li>While selecting the destination address of the bypass LSP, the
	LSP, the PLR MUST select the router ID of the NNhop or Nhop	PLR <bcp14>MUST</bcp14> select the router ID of the NNHOP or NHOP
	node from the Node-ID sub-object included in the RRO object car	node from the Node-ID sub-object included in the RRO that is
	ried	carried in the most recent Resv message corresponding to the
	in the most recent Resv message corresponding to the LSP. If th	LSP. If the MP has not included a Node-ID sub-object in the Resv
	e	RRO and if the PLR and the MP are in the same area, then the PLR
	MP has not included a Node-ID sub-object in the Resv RRO and if	may utilize the TED to determine the router ID corresponding to
	the	the interface address that is included by the MP in the RRO. If the
	PLR and the MP are in the same area, then the PLR may utilize t	NP-MP in a different IGP area has not included a Node-ID
	he	sub-object in the RRO, then the PLR <bcp14>MUST</bcp14> execute
	TED to determine the router ID corresponding to the interface	backward compatibility procedures as if the downstream nodes along
	address included by the MP in the RRO object. If the NP-MP in a	the LSP do not support the extensions defined in the document (see
	different IGP area has not included a Node-ID sub-object in RRO	<xref target="dnstr_no_support"/>).</li>
	object, then the PLR MUST execute backward compatibility proced
	ures
	as if the downstream nodes along the LSP do not support the ext
	ensions
	defined in the document (see <xref target="dnstr_no_support"/>)
	.
	</t>
	</list>
	<list style="hanging">
	<t hangText="-">The PLR MUST also include its router ID in a
	Node-ID sub-object in RRO object carried in any subsequent Path
	message corresponding to the LSP. While including its router ID
	in
	the Node-ID sub-object carried in the outgoing Path message, th
	e
	PLR MUST include the Node-ID sub-object after including its
	IPv4/IPv6 address or unnumbered interface ID sub-object.
	</t>
	</list>
	<list style="hanging">
	<t hangText="-">In parallel to the attempt made to create NP-bypass
	or LP-bypass, the PLR MUST initiate a Node-ID based Hello
	session to the NNhop or Nhop node respectively along the LSP to
	establish the RSVP-TE signaling adjacency. This Hello session i
	s
	used to detect MP node failure as well as determine the capabil
	ity
	of the MP node. If the MP has set the I-bit in the CAPABILITY
	object <xref target="RFC8370"/> carried in Hello message
	corresponding to the Node-ID based Hello session, then the PLR
	MUST conclude that the MP supports refresh-interval
	independent FRR procedures defined in this document. If the
	MP has not sent Node-ID based Hello messages or has not set
	the I-bit in CAPABILITY object <xref target="RFC8370"/>,
	then the PLR MUST execute backward compatibility procedures
	defined in <xref target="dnstr_no_support"/> of this document.
	</t>
	</list>
	<list style="hanging">
	<t hangText="-">When the PLR associates a bypass to a protected LSP, it
	MUST include a B-SFRR-Ready Extended Association object
	<xref target="RFC8796"/> and trigger a Path message to be sent
	for the LSP. If a B-SFRR-Ready Extended Association object is
	included in the Path message corresponding to the LSP, the
	encoding and object ordering rules specified in RSVP-TE Summary
	FRR
	<xref target="RFC8796"/> MUST be followed. In addition to those
	rules, the PLR MUST set the Association Source in the object to
	its
	Node-ID address.
	</t>
	</list>
	</t>


	</section>	<li>The PLR <bcp14>MUST</bcp14> also include its router ID in a
		Node-ID sub-object in the RRO that is carried in any subsequent Path
		message corresponding to the LSP. While doing so, the
		PLR <bcp14>MUST</bcp14> include the Node-ID sub-object after
		including its IPv4/IPv6 address or unnumbered interface ID
		sub-object.</li>


	<section anchor="sig_rem_adjacency" title="Remote Signaling Adjacency">	<li>In parallel to the attempt made to create an NP-bypass or an
	<t>A Node-ID based RSVP-TE Hello session is one in which Node-ID is	LP-bypass, the PLR <bcp14>MUST</bcp14> initiate a Node-ID-based
		Hello session to the NNHOP or NHOP node respectively along the LSP
		to establish the RSVP-TE signaling adjacency. This Hello session
		is used to detect MP node failure as well as to determine the
		capability of the MP node. The
		PLR <bcp14>MUST</bcp14> conclude that the MP supports the refresh-in
		terval independent FRR procedures defined in this
		document if the MP has set the I-bit in the
		CAPABILITY object <xref target="RFC8370"/> carried in the Hello
		message corresponding to the Node-ID-based Hello session.
		If the MP has not sent Node-ID-based Hello messages or
		has not set the I-bit in the CAPABILITY object <xref
		target="RFC8370"/>, then the PLR <bcp14>MUST</bcp14> execute
		backward compatibility procedures defined in <xref
		target="dnstr_no_support"/> of this document.</li>
		<li>When the PLR associates a bypass to a protected LSP, it
		<bcp14>MUST</bcp14> include a B-SFRR-Ready Extended ASSOCIATION
		object <xref target="RFC8796"/> and trigger a Path message to be
		sent for the LSP. If a B-SFRR-Ready Extended ASSOCIATION object is
		included in the Path message corresponding to the LSP, the
		encoding and object ordering rules specified in RSVP-TE Summary
		FRR <xref target="RFC8796"/> <bcp14>MUST</bcp14> be followed. In
		addition to those rules, the PLR <bcp14>MUST</bcp14> set the
		Association Source in the object to its Node-ID address.</li>
		</ul>
		</section>
		<section anchor="sig_rem_adjacency">
		<name>Remote Signaling Adjacency</name>
		<t>A Node-ID-based RSVP-TE Hello session is one in which a Node-ID is
	used in the source and the destination address fields of RSVP Hello	used in the source and the destination address fields of RSVP Hello

	messages <xref target="RFC4558"/>. This document extends Node-ID based	messages <xref target="RFC4558"/>. This document extends Node-ID-based
	RSVP Hello session to track the state of any RSVP-TE neighbor that is	RSVP Hello sessions to track the state of any RSVP-TE neighbor that is
	not directly connected by at least one interface. In order to apply	not directly connected by at least one interface. In order to apply

	Node-ID based RSVP-TE Hello session between any two routers that are	Node-ID-based RSVP-TE Hello sessions between any two routers that are
	not immediate neighbors, the router that supports the extensions	not immediate neighbors, the router that supports the extensions

	defined in the document MUST set TTL to 255 in all outgoing	defined in the document <bcp14>MUST</bcp14> set the TTL to 255 in all
	Node-ID based Hello messages exchanged between the PLR and the MP. The	outgoing
	default hello interval for this Node-ID hello session MUST be set	Node-ID-based Hello messages exchanged between the PLR and the MP. The
		default hello interval for this Node-ID Hello session <bcp14>MUST</bcp
		14> be set
	to the default specified in RSVP-TE Scaling Techniques	to the default specified in RSVP-TE Scaling Techniques
	<xref target="RFC8370"/>.	<xref target="RFC8370"/>.

	</t>	</t>
		<t>In the rest of the document, the terms "signaling adjacency"
	<t>In the rest of the document the term "signaling adjacency",	and "remote signaling adjacency" refer specifically to the
	or "remote signaling adjacency" refers specifically to the
	RSVP-TE signaling adjacency.	RSVP-TE signaling adjacency.

	</t>	</t>
	</section>	</section>
		<section anchor="sig_mp_behavior">
	<section anchor="sig_mp_behavior" title="MP Behavior">	<name>MP Behavior</name>
	<t>With regard to the MP procedures that are defined in	<t>With regard to the MP procedures that are defined in
	<xref target="RFC4090"/> this document specifies the following	<xref target="RFC4090"/>, this document specifies the following
	additional procedures to support RI-RSVP defined in	additional procedures to support RI-RSVP as defined in
	<xref target="RFC8370"/>.	<xref target="RFC8370"/>.

	</t>	</t>
		<t>Each node along an LSP supporting the extensions defined in
	<t>Each node along an LSP path supporting the extensions defined in	this document <bcp14>MUST</bcp14> also include its router ID in the No
	this document MUST also include its router ID in the Node-ID	de-ID
	sub-object of the RRO object carried in the Resv message of the	sub-object of the RRO that is carried in the Resv message of the
	corresponding LSP. If the PLR has not included a Node-ID sub-object	corresponding LSP. If the PLR has not included a Node-ID sub-object

	in the RRO object carried in the Path message and if the PLR is in	in the RRO that is carried in the Path message and if the PLR is in
	a different IGP area, then the router MUST NOT execute the MP	a different IGP area, then the router <bcp14>MUST NOT</bcp14> execute
		the MP
	procedures specified in this document for those LSPs. Instead, the	procedures specified in this document for those LSPs. Instead, the

	node MUST execute backward compatibility procedures defined in	node <bcp14>MUST</bcp14> execute backward compatibility procedures def ined in
	<xref target="upstr_no_support"/> of this document as if the upstream nodes along	<xref target="upstr_no_support"/> of this document as if the upstream nodes along
	the LSP do not support the extensions defined in this document.	the LSP do not support the extensions defined in this document.

	</t>	</t>

	<t>A node receiving a Path message should determine whether the
	message contains a B-SFRR-Ready Extended Association object with
	its own address as the bypass destination address and whether it
	has an operational Node-ID signaling adjacency with the Association
	source. If the PLR has not included the B-SFRR-Ready Extended
	Association object or if there is no operational Node-ID signaling
	adjacency with the PLR identified by the Association source address
	or if the PLR has not advertised RI-RSVP capability in its
	Node-ID based Hello messages, then the node MUST execute the
	backward compatibility procedures defined in
	<xref target="upstr_no_support"/> of this document.
	</t>

	<t>If a matching B-SFRR-Ready Extended Association object is found in
	in the Path message and if there is an operational remote Node-ID
	signaling adjacency with the PLR (identified by the Association
	source) that has advertised RI-RSVP capability (I-bit)
	<xref target="RFC8370"/>, then the node MUST consider itself as the
	MP for the PLR. The matching and ordering rules for Bypass Summary
	FRR Extended Association specified in RSVP-TE Summary FRR
	<xref target="RFC8796"/> MUST be followed by the implementations
	supporting this document.


	<list style="hanging">	<t>A node receiving a Path message should determine:</t>
	<t hangText="-">If a matching Bypass Summary FRR Extended Association	<ul>
	object is included by the PPhop node of an LSP and if a	<li>whether the message contains a B-SFRR-Ready Extended
	corresponding Node-ID signaling adjacency exists with the	ASSOCIATION object with its own address as the bypass destination
	PPhop node, then the router MUST conclude it is the NP-MP.	address and</li>
	</t>	<li>whether it has an operational Node-ID signaling adjacency with
	</list>	the Association Source.</li>
	<list style="hanging">	</ul>
	<t hangText="-">If a matching Bypass Summary FRR Extended Association
	object is included by the Phop node of an LSP and if a
	corresponding Node-ID signaling adjacency exists with the Phop
	node, then the router MUST conclude it is the LP-MP.
	</t>
	</list>
	</t>
	</section>


	<section anchor="sig_rem_state" title=""Remote" State on MP">	<t>The node <bcp14>MUST</bcp14> execute the
	<t>Once a router concludes it is the MP for a PLR running	backward compatibility procedures defined in
	refresh-interval independent FRR procedures as described in the	<xref target="upstr_no_support"/> of this document if:</t>
	preceding section, it MUST create a remote path state for the LSP.	<ul>
	The only difference between the "remote" path state and	<li>the PLR has not included the B-SFRR-Ready Extended
	the LSP state is the RSVP_HOP object. The RSVP_HOP object in a	ASSOCIATION object,</li>
	"remote" path state contains the address that the PLR	<li>there is no operational Node-ID signaling
	uses to send Node-ID hello messages to the MP.	adjacency with the PLR identified by the Association Source address, o
	</t>	r</li>
		<li>the PLR has not advertised the RI-RSVP capability in its
		Node-ID-based Hello messages.</li>
		</ul>
		<t>If a matching B-SFRR-Ready Extended ASSOCIATION object is found
		in the Path message and if there is an operational remote Node-ID
		signaling adjacency with the PLR (identified by the Association
		Source) that has advertised the RI-RSVP capability (I-bit) <xref
		target="RFC8370"/>, then the node <bcp14>MUST</bcp14> consider
		itself as the MP for the PLR. The matching and ordering rules for
		Bypass Summary FRR Extended Association specified in RSVP-TE Summary
		FRR <xref target="RFC8796"/> <bcp14>MUST</bcp14> be followed by the
		implementations supporting this document.
		</t>
		<ul>
		<li>If a matching Bypass Summary FRR Extended Association object
		is included by the PPHOP node of an LSP and if a corresponding
		Node-ID signaling adjacency exists with the PPHOP node, then the
		router <bcp14>MUST</bcp14> conclude it is the NP-MP.</li>
		<li>If a matching Bypass Summary FRR Extended Association object
		is included by the PHOP node of an LSP and if a corresponding
		Node-ID signaling adjacency exists with the PHOP node, then the
		router <bcp14>MUST</bcp14> conclude it is the LP-MP.</li>
		</ul>
		</section>


	<t>The MP MUST consider the "remote" path state corresponding	<section anchor="sig_rem_state">
		<name>"Remote" State on MP</name>
		<t>Once a router concludes it is the MP for a PLR running
		refresh-interval independent FRR procedures as described in the
		preceding section, it <bcp14>MUST</bcp14> create a remote path state
		for the LSP. The only difference between the "remote" path state
		and the LSP state is the RSVP_HOP object. The RSVP_HOP object in a
		"remote" path state contains the address that the PLR uses to send
		Node-ID Hello messages to the MP.
		</t>
		<t>The MP <bcp14>MUST</bcp14> consider the "remote" path state corresp
		onding
	to the LSP automatically deleted if:	to the LSP automatically deleted if:

		</t>
	<list style="hanging">	<ul>
	<t hangText="-">The MP later receives a Path message for the LSP with	<li>the MP later receives a Path message for the LSP with no
	no matching B-SFRR-Ready Extended Association object correspond	matching B-SFRR-Ready Extended ASSOCIATION object corresponding to
	ing	the PLR's IP address contained in the Path RRO,</li>
	to the PLR's IP address contained in the Path RRO, or	<li>the Node-ID signaling adjacency with the PLR goes down,</li>
	</t>	<li>the MP receives backup LSP signaling for the LSP from the PLR,</
	</list>	li>
	<list style="hanging">	<li>the MP receives a PathTear for the LSP, or</li>
	<t hangText="-">The Node-ID signaling adjacency with the PLR goes down,	<li>the MP deletes the LSP state on a local policy or an exception e
	or	vent.</li>
	</t>	</ul>
	</list>	<t>The purpose of "remote" path state is to enable the PLR
	<list style="hanging">
	<t hangText="-">The MP receives backup LSP signaling for the LSP from t
	he PLR or
	</t>
	</list>
	<list style="hanging">
	<t hangText="-">The MP receives a PathTear for the LSP, or
	</t>
	</list>
	<list style="hanging">
	<t hangText="-">The MP deletes the LSP state on a local policy or an ex
	ception event
	</t>
	</list>
	</t>

	<t>The purpose of "remote" path state is to enable the PLR
	to explicitly tear down the path and reservation states corresponding	to explicitly tear down the path and reservation states corresponding

	to the LSP by sending a tear message for the "remote" path	to the LSP by sending a tear message for the "remote" path
	state. Such a message tearing down "remote" path state is	state. Such a message tearing down the "remote" path state is
	called "Remote" PathTear.	called "Remote" PathTear.
	</t>	</t>
		<t>The scenarios in which a "Remote" PathTear is applied are
	<t>The scenarios in which a "Remote" PathTear is applied are
	described in <xref target="rem_tear"/> of this document.	described in <xref target="rem_tear"/> of this document.

	</t>	</t>
	</section>	</section>
	</section>	</section>
		<section anchor="failures">
	<section anchor="failures" title="Impact of Failures on LSP State">	<name>Impact of Failures on LSP State</name>
	<t>This section describes the procedures that must be executed upon	<t>This section describes the procedures that must be executed upon
	different kinds of failures by nodes along the path of the LSP. The	different kinds of failures by nodes along the path of the LSP. The
	procedures that must be executed upon detecting RSVP signaling adjacenc y	procedures that must be executed upon detecting RSVP signaling adjacenc y
	failures do not impact the RSVP-TE graceful restart mechanisms	failures do not impact the RSVP-TE graceful restart mechanisms

	(<xref target="RFC3473"/>, <xref target="RFC5063"/>). If a node	<xref target="RFC3473"/> <xref target="RFC5063"/>. If a node
	executing these procedures acts as a helper for a neighboring router,	executing these procedures acts as a helper for a neighboring router,
	then the signaling adjacency with the neighbor will be declared as havi ng	then the signaling adjacency with the neighbor will be declared as havi ng
	failed only after taking into account the grace period extended for the	failed only after taking into account the grace period extended for the
	neighbor by this node acting as a helper.	neighbor by this node acting as a helper.

	</t>	</t>
		<t>Node failures are detected from the state of Node-ID Hello
	<t>Node failures are detected from the state of Node-ID hello
	sessions established with immediate neighbors. RSVP-TE Scaling	sessions established with immediate neighbors. RSVP-TE Scaling
	Techniques <xref target="RFC8370"/> recommends that each node	Techniques <xref target="RFC8370"/> recommends that each node

	establish Node-ID hello sessions with all its immediate neighbors.	establish Node-ID Hello sessions with all its immediate neighbors.
	Non-immediate PLR or MP failure is detected from the state of remote	A non-immediate PLR or MP failure is detected from the state of remote
	signaling adjacency established according to	signaling adjacency established according to
	<xref target="sig_rem_adjacency"/> of this document.	<xref target="sig_rem_adjacency"/> of this document.

	</t>	</t>
		<section anchor="failures_nonmp">
	<section anchor="failures_nonmp" title="Non-MP Behavior">	<name>Non-MP Behavior</name>
	<t>When a router detects the Phop link or the Phop node failure for an LS	<t>When a router detects the PHOP link or the PHOP node failure for an
	P	LSP
	and the router is not an MP for the LSP, then it MUST send a Condition	and the router is not an MP for the LSP, then it <bcp14>MUST</bcp14> s
	al	end a Conditional
	PathTear (refer to <xref target="cnd_path_tear"/> of this document)	PathTear (refer to <xref target="cnd_path_tear"/> of this document)
	and delete the PSB and RSB states corresponding to	and delete the PSB and RSB states corresponding to
	the LSP.	the LSP.

	</t>	</t>
	</section>	</section>
		<section anchor="failures_lpmp">
	<section anchor="failures_lpmp" title="LP-MP Behavior">	<name>LP-MP Behavior</name>
	<t>When the Phop link for an LSP fails on a router that is an LP-MP for	<t>When the PHOP link for an LSP fails on a router that is an LP-MP fo
	the LSP, the LP-MP MUST retain the PSB and RSB states corresponding	r
	to the LSP till the occurrence of any of the following events.	the LSP, the LP-MP <bcp14>MUST</bcp14> retain the PSB and RSB states c
		orresponding
	<list style="hanging">	to the LSP until the occurrence of any of the following events:
	<t hangText="-">The Node-ID signaling adjacency with the Phop PLR goes d	</t>
	own, or	<ul>
	</t>	<li>the Node-ID signaling adjacency with the PHOP PLR goes down,</li
	</list>	>
	<list style="hanging">	<li>the MP receives a normal or "Remote" PathTear for its PSB, or</l
	<t hangText="-">The MP receives a normal or "Remote" PathTear	i>
	for its PSB, or	<li>the MP receives a ResvTear for its RSB.</li>
	</t>	</ul>
	</list>	<t>When a router that is an LP-MP for an LSP detects PHOP node failure
	<list style="hanging">	from the Node-ID signaling adjacency state, the LP-MP <bcp14>MUST</bcp
	<t hangText="-">The MP receives a ResvTear for its RSB.	14> send a normal
	</t>
	</list>
	</t>

	<t>When a router that is an LP-MP for an LSP detects Phop node failure
	from the Node-ID signaling adjacency state, the LP-MP MUST send a norm
	al
	PathTear and delete the PSB and RSB states corresponding to the LSP.	PathTear and delete the PSB and RSB states corresponding to the LSP.

	</t>	</t>
	</section>	</section>

	<section anchor="failures_npmp" title="NP-MP Behavior">
	<t>When a router that is an NP-MP for an LSP detects Phop link failure,
	or Phop node failure from the Node-ID signaling adjacency, the router
	MUST retain the PSB and RSB states corresponding to the LSP till the
	occurrence of any of the following events.

	<list style="hanging">
	<t hangText="-">The remote Node-ID signaling adjacency with the PPhop PL
	R goes down, or
	</t>
	</list>
	<list style="hanging">
	<t hangText="-">The MP receives a normal or "Remote" PathTear
	for its PSB, or
	</t>
	</list>
	<list style="hanging">
	<t hangText="-">The MP receives a ResvTear for its RSB.
	</t>
	</list>
	</t>

	<t>When a router that is an NP-MP for an LSP did not detect the Phop link
	or the Phop node failure, but receives a Conditional PathTear from the
	Phop node, then the router MUST retain the PSB and RSB states correspo
	nding to the
	LSP till the occurrence of any of the following events.

	<list style="hanging">
	<t hangText="-">The remote Node-ID signaling adjacency with the PPhop PL
	R goes down, or
	</t>
	</list>
	<list style="hanging">
	<t hangText="-">The MP receives a normal or "Remote" PathTear
	for its PSB, or
	</t>
	</list>
	<list style="hanging">
	<t hangText="-">The MP receives a ResvTear for its RSB.
	</t>
	</list>
	</t>


	<t>Receiving a Conditional PathTear from the Phop node will not impact	<section anchor="failures_npmp">
	the "remote" state from the PPhop PLR. Note that the Phop	<name>NP-MP Behavior</name>
	node must have sent the Conditional PathTear as it was not an MP for	<t>When a router that is an NP-MP for an LSP detects PHOP link failure
	the LSP (see <xref target="failures_nonmp"/> of this document).	or PHOP node failure from the Node-ID signaling adjacency, the router
	</t>	<bcp14>MUST</bcp14> retain the PSB and RSB states corresponding to the
		LSP until the
		occurrence of any of the following events:
		</t>
		<ul>
		<li>the remote Node-ID signaling adjacency with the PPHOP PLR goes d
		own,</li>
		<li>the MP receives a normal or "Remote" PathTear for its PSB, or</l
		i>
		<li>the MP receives a ResvTear for its RSB.</li>
		</ul>
		<t>When a router that is an NP-MP for an LSP does not detect the PHOP
		link or the PHOP node failure but receives a Conditional PathTear
		from the PHOP node, then the router <bcp14>MUST</bcp14> retain the
		PSB and RSB states corresponding to the LSP until the occurrence of
		any of the following events:
		</t>
		<ul>
		<li>the remote Node-ID signaling adjacency with the PPHOP PLR goes d
		own,</li>
		<li>the MP receives a normal or "Remote" PathTear for its PSB, or</l
		i>
		<li>the MP receives a ResvTear for its RSB.</li>
		</ul>
		<t>Receiving a Conditional PathTear from the PHOP node will not
		impact the "remote" state from the PPHOP PLR. Note that the PHOP
		node must have sent the Conditional PathTear as it was not an MP for
		the LSP (see <xref target="failures_nonmp"/> of this document).
		</t>


	<t>In the example topology <xref target="example_network"/>, we assume	<t>In the example topology in <xref target="example_network"/>, we ass
	C & D are the NP-MPs for the PLRs A & B respectively. Now when	ume
	A-B link fails, as B is not an MP and its Phop link has failed, B will	C and D are the NP-MPs for the PLRs A and B, respectively. Now, when t
	delete the LSP state (this behavior is required for unprotected LSPs -	he
		A-B link fails, B will delete the LSP state, because B is not an MP an
		d its PHOP link has failed (this behavior is required for unprotected LSPs;
	refer to <xref target="failures_nonmp"/> of this document). In the dat a	refer to <xref target="failures_nonmp"/> of this document). In the dat a
	plane, that would require B to delete the label forwarding entry	plane, that would require B to delete the label forwarding entry

	corresponding to the LSP. So if B's downstream nodes C and D continue to	corresponding to the LSP. Thus, if B's downstream nodes C and D contin ue to
	retain state, it would not be correct for D to continue to assume itse lf	retain state, it would not be correct for D to continue to assume itse lf
	as the NP-MP for the PLR B.	as the NP-MP for the PLR B.

	</t>	</t>
		<t>The mechanism that enables D to stop considering itself as the
	<t>The mechanism that enables D to stop considering itself as the	NP-MP for B and delete the corresponding "remote" path
	NP-MP for B and delete the corresponding "remote" path
	state is given below.	state is given below.

		</t>
		<ol>
		<li>When C receives a Conditional PathTear from B, it decides to
		retain the LSP state as it is the NP-MP of the PLR A. It also check
		s
		whether PHOP B had previously signaled availability of node
		protection. As B had previously signaled NP availability by
		including the B-SFRR-Ready Extended ASSOCIATION object, C removes th
		e
		B-SFRR-Ready Extended ASSOCIATION object containing the Association
		Source set to B from the Path message and triggers a Path to
		D.</li>
		<li>When D receives the Path message, it realizes that it is no
		longer the NP-MP for B and so it deletes the corresponding
		"remote" path state. D does not propagate the Path further down
		because the only change is that the B-SFRR-Ready Extended
		ASSOCIATION object corresponding to Association Source B is no
		longer present in the Path message.</li>
		</ol>
		</section>


	<list style="hanging">	<section anchor="failures_lpnpmp">
	<t hangText="1.">When C receives a Conditional PathTear from B, it	<name>Behavior of a Router That Is Both the LP-MP and NP-MP</name>
	decides to retain LSP state as it is the NP-MP of the PLR A.	<t>A router may simultaneously be the LP-MP and the NP-MP for the
	It also checks whether Phop B had previously signaled	PHOP and PPHOP nodes of an LSP, respectively. If the PHOP link
	availability of node protection. As B had previously signaled	fails on such a node, the node <bcp14>MUST</bcp14> retain the PSB
	NP availability by including B-SFRR-Ready Extended Association	and RSB states corresponding to the LSP until the occurrence of any
	object, C removes the B-SFRR-Ready Extended Association	of the following events:
	object containing Association Source set to B from the Path	</t>
	message and trigger a Path to D.	<ul>
	</t>	<li>both Node-ID signaling adjacencies with PHOP and PPHOP nodes go
	</list>	down,</li>
	<list style="hanging">	<li>the MP receives a normal or "Remote" PathTear for its PSB, or</l
	<t hangText="2.">When D receives the Path message, it realizes that it	i>
	is no longer the NP-MP for B and so it deletes the	<li>the MP receives a ResvTear for its RSB.</li>
	corresponding "remote" path state. D does not	</ul>
	propagate the Path further down because the only change is that	<t>If a router that is both an LP-MP and an NP-MP detects PHOP node
	the B-SFRR-Ready Extended Association object corresponding to	failure, then the node <bcp14>MUST</bcp14> retain the PSB and RSB stat
	Association Source B is no longer present in the Path message.	es corresponding
	</t>	to the LSP until the occurrence of any of the following events:
	</list>	</t>
	</t>	<ul>
	</section>	<li>the remote Node-ID signaling adjacency with the PPHOP PLR goes d
		own,</li>
	<section anchor="failures_lpnpmp" title="Behavior of a Router that is both	<li>the MP receives a normal or "Remote" PathTear for its PSB, or</l
	LP-MP and NP-MP">	i>
	<t>A router may simultaneously be the LP-MP as well as the NP-MP for the	<li>the MP receives a ResvTear for its RSB.</li>
	Phop and the PPhop nodes respectively of an LSP. If the Phop link fail	</ul>
	s	</section>
	on such a node, the node MUST retain the PSB and RSB states correspond	</section>
	ing
	to the LSP till the occurrence of any of the following events.

	<list style="hanging">
	<t hangText="-">Both Node-ID signaling adjacencies with Phop and PPhop n
	odes go down, or
	</t>
	</list>
	<list style="hanging">
	<t hangText="-">The MP receives a normal or "Remote" PathTear
	for its PSB, or
	</t>
	</list>
	<list style="hanging">
	<t hangText="-">The MP receives a ResvTear for its RSB.
	</t>
	</list>
	</t>

	<t>If a router that is both an LP-MP and an NP-MP detects Phop node
	failure, then the node MUST retain the PSB and RSB states correspondin
	g
	to the LSP till the occurrence of any of the following events.

	<list style="hanging">
	<t hangText="-">The remote Node-ID signaling adjacency with the PPhop PL
	R goes down, or
	</t>
	</list>
	<list style="hanging">
	<t hangText="-">The MP receives a normal or "Remote" PathTear
	for its PSB, or
	</t>
	</list>
	<list style="hanging">
	<t hangText="-">The MP receives a ResvTear for its RSB.
	</t>
	</list>
	</t>
	</section>

	</section>


	<section anchor="cnd_path_tear" title="Conditional PathTear">	<section anchor="cnd_path_tear">
	<t>In the example provided in <xref target="failures_npmp"/> of this docu	<name>Conditional PathTear</name>
	ment, B	<t>In the example provided in <xref target="failures_npmp"/> of this
	deletes the PSB and RSB states corresponding to the LSP once B detects	document, B deletes the PSB and RSB states corresponding to the LSP
	its Phop link went down as B is not an MP. If B were to send a	once B detects its PHOP link has gone down as B is not an MP. If B
	PathTear normally, then C would delete LSP state immediately. In	were to send a PathTear normally, then C would delete the LSP state
	order to avoid this, there should be some mechanism by which B can	immediately. In order to avoid this, there should be some mechanism by
	indicate to C that B does not require the receiving node to	which B can indicate to C that B does not require the receiving node
	unconditionally delete the LSP state immediately. For this, B MUST	to unconditionally delete the LSP state immediately. For this, B
	add a new optional CONDITIONS object in the PathTear. The CONDITIONS	<bcp14>MUST</bcp14> add a new optional CONDITIONS object in the
	object is defined in <xref target="cnd_path_tear_obj"/> of this documen	PathTear. The CONDITIONS object is defined in <xref
	t. If node C	target="cnd_path_tear_obj"/> of this document. If node C also
	also understands the new object, then C MUST NOT delete the LSP state	understands the new object, then C <bcp14>MUST NOT</bcp14> delete the
	if it is an NP-MP.	LSP state if it is an NP-MP.
	</t>	</t>


	<section anchor="cnd_path_tear_send" title="Sending Conditional PathTear">	<section anchor="cnd_path_tear_send">
	<t>A router that is not an MP for an LSP MUST delete the PSB and RSB	<name>Sending the Conditional PathTear</name>
	states corresponding to the LSP if the Phop link or the Phop Node-ID	<t>A router that is not an MP for an LSP <bcp14>MUST</bcp14> delete th
		e PSB and RSB
		states corresponding to the LSP if the PHOP link or the PHOP Node-ID
	signaling adjacency goes down (see <xref target="failures_nonmp"/> of this document).	signaling adjacency goes down (see <xref target="failures_nonmp"/> of this document).

	The router MUST send a Conditional PathTear if the following are also	The router <bcp14>MUST</bcp14> send a Conditional PathTear if the foll
	true.	owing are also
		true:
	<list style="hanging">	</t>
	<t hangText="-">The ingress has requested node protection for the LSP, a	<ul>
	nd	<li>the ingress has requested node protection for the LSP and</li>
	</t>	<li>no PathTear is received from the upstream node.</li>
	</list>	</ul>
	<list style="hanging">	</section>
	<t hangText="-">No PathTear is received from the upstream node
	</t>
	</list>
	</t>
	</section>


	<section anchor="cnd_path_tear_recv" title="Processing Conditional PathTear	<section anchor="cnd_path_tear_recv">
	">	<name>Processing the Conditional PathTear</name>
	<t>When a router that is not an NP-MP receives a Conditional PathTear,	<t>When a router that is not an NP-MP receives a Conditional PathTear,
	the node MUST delete the PSB and RSB states corresponding to the LSP,	the node <bcp14>MUST</bcp14> delete the PSB and RSB states correspondi
		ng to the LSP
	and process the Conditional PathTear by considering it as a normal	and process the Conditional PathTear by considering it as a normal

	PathTear. Specifically, the node MUST NOT propagate the Conditional	PathTear. Specifically, the node <bcp14>MUST NOT</bcp14> propagate the Conditional
	PathTear downstream but remove the optional object and send a normal	PathTear downstream but remove the optional object and send a normal
	PathTear downstream.	PathTear downstream.

	</t>	</t>
		<t>When a node that is an NP-MP receives a Conditional PathTear, it
	<t>When a node that is an NP-MP receives a Conditional PathTear, it	<bcp14>MUST NOT</bcp14> delete the LSP state. The node <bcp14>MUST</bc
	MUST NOT delete LSP state. The node MUST check whether the	p14> check whether the
	Phop node had previously included the B-SFRR-Ready Extended Associatio	PHOP node had previously included the B-SFRR-Ready Extended ASSOCIATIO
	n	N
	object in the Path. If the object had been included previously by the	object in the Path. If the object had been included previously by the

	Phop, then the node processing the Conditional PathTear from the Phop	PHOP, then the node processing the Conditional PathTear from the PHOP
	MUST remove the corresponding object and trigger a Path downstream.	<bcp14>MUST</bcp14> remove the corresponding object and trigger a Path
	</t>	downstream.
		</t>
	<t>If a Conditional PathTear is received from a neighbor that has not	<t>If a Conditional PathTear is received from a neighbor that has not
	advertised support (refer to <xref target="compatible"/> of this docum ent) for the	advertised support (refer to <xref target="compatible"/> of this docum ent) for the

	new procedures defined in this document, then the node MUST	new procedures defined in this document, then the node <bcp14>MUST</bc
	consider the message as a normal PathTear. The node MUST propagate	p14>
		consider the message as a normal PathTear. The node <bcp14>MUST</bcp14
		> propagate
	the normal PathTear downstream and delete the LSP state.	the normal PathTear downstream and delete the LSP state.

	</t>	</t>
	</section>	</section>
		<section anchor="cnd_path_tear_obj">
	<section anchor="cnd_path_tear_obj" title="CONDITIONS Object">	<name>CONDITIONS Object</name>
	<t>Any implementation that does not support Conditional PathTear	<t>Any implementation that does not support a Conditional PathTear
	needs to ignore the new object but process the message as a normal	needs to ignore the new object but process the message as a normal
	PathTear without generating any error. For this reason, the Class-Num	PathTear without generating any error. For this reason, the Class-Num

	of the new object follows the pattern 10bbbbbb where 'b' represents a	of the new object follows the pattern 10bbbbbb, where "b" represents a
	bit.	bit.
	(The behavior for objects of this type is specified in Section 3.10 of	(The behavior for objects of this type is specified in <xref target="R
	<xref target="RFC2205"/>).	FC2205" sectionFormat="of" section="3.10"/>.)
	</t>	</t>
		<t>The new object is called the "CONDITIONS" object and will
	<t>The new object is called as "CONDITIONS" object that will
	specify the conditions under which default processing rules of the	specify the conditions under which default processing rules of the

	RSVP-TE message MUST be invoked.	RSVP-TE message <bcp14>MUST</bcp14> be invoked.
	</t>	</t>
		<t>The object has the following format:</t>
	<t>The object has the following format:	<figure anchor="fig_conditions">
		<name>CONDITIONS Object</name>
	<figure align="left" anchor="fig_conditions" title="CONDITIONS Object">	<artwork align="left"><![CDATA[
	<artwork>
	<![CDATA[
	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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	\| Length \| Class \| C-type \|	\| Length \| Class \| C-type \|
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	\| Flags (Reserved) \|M\|	\| Flags (Reserved) \|M\|
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

	]]>	]]></artwork>
	</artwork>	</figure>
	</figure>


	<?rfc subcompact="yes" ?>	<dl spacing="compact" newline="false">
	<list style="none">	<dt>Class:</dt> <dd>135</dd>
	<t>Class: TBA1<br></br>	<dt>C-type:</dt> <dd>1</dd>
	C-type: 1<br></br>	<dt>Flags:</dt> <dd>32 bit field</dd>
	Flags is a 32 bit field. Bit 31 is the Merge-point condition (M) bi	<dt>M:</dt> <dd>Bit 31 is the Merge-point condition (M) bit.
	t:	If the M bit is set to 1, then the PathTear message <bcp14>MUST</bc
	If the M bit is set to 1, then the PathTear message MUST be process	p14> be processed
	ed	according to the receiver router role, i.e., if the receiving route
	according to the receiver router role, i.e. if the receiving router	r
	is an MP or not for the LSP. If it is not set, then the PathTear	is an MP or not for the LSP. If it is not set, then the PathTear

	message MUST be processed as a normal PathTear message for the LSP.	message <bcp14>MUST</bcp14> be processed as a normal PathTear messa
	<br></br>	ge for the LSP.</dd>
	Bits 0-30 are reserved, they MUST be set to zero on transmission an	</dl>
	d	<t>Bits 0-30 are reserved; they <bcp14>MUST</bcp14> be set to zero on transmis
	MUST be ignored on receipt.<br></br>	sion and
	</t>	<bcp14>MUST</bcp14> be ignored on receipt.</t>
	</list>	</section>
	</t>	</section>
	</section>

	</section>


	<section anchor="rem_tear" title="Remote State Teardown">	<section anchor="rem_tear">
	<t>If the ingress wants to tear down the LSP because of a management	<name>Remote State Teardown</name>
		<t>If the ingress wants to tear down the LSP because of a management
	event while the LSP is being locally repaired at a transit PLR, it	event while the LSP is being locally repaired at a transit PLR, it

	would not be desirable to wait till the completion of backup LSP	would not be desirable to wait until the completion of backup LSP
	signaling to perform state cleanup. In this case, the PLR MUST send a	signaling to perform state cleanup. In this case, the PLR <bcp14>MUST<
	"Remote" PathTear message instructing the MP to delete the P	/bcp14> send a
	SB	"Remote" PathTear message instructing the MP to delete the PSB
	and RSB states corresponding to the LSP. The TTL in the "Remote&q	and RSB states corresponding to the LSP. The TTL in the "Remote"
	uot;	PathTear message <bcp14>MUST</bcp14> be set to 255. Doing this enables
	PathTear message MUST be set to 255. Doing this enables LSP state clea	LSP state cleanup
	nup
	when the LSP is being locally repaired.	when the LSP is being locally repaired.

	</t>	</t>
	<t>Consider that node C in the example topology	<t>Consider that node C in the example topology
	(<xref target="example_network"/>) has gone down and node B locally	(<xref target="example_network"/>) has gone down and node B locally

	repairs the LSP.	repairs the LSP:
	<list style="hanging">	</t>
	<t hangText="1.">Ingress A receives a management event to tear down the	<ol>
	LSP.	<li>Ingress A receives a management event to tear down the LSP.</li>
	</t>	<li>A sends a normal PathTear for the LSP to B.</li>
	</list>	<li>Assume B has not initiated the backup signaling for the
	<list style="hanging">	LSP during local repair. To enable LSP state cleanup, B sends a
	<t hangText="2.">A sends a normal PathTear for the LSP to B.	"Remote" PathTear with the destination IP address set to
	</t>	that of the node D used in the Node-ID signaling adjacency with D
	</list>	and the RSVP_HOP object containing the local address used in the
	<list style="hanging">	Node-ID signaling adjacency.</li>
	<t hangText="3.">Assume B has not initiated the backup signaling for the	<li>B then deletes the PSB and RSB states corresponding to the LSP.</li
	LSP during local repair. To enable LSP state cleanup, B sends a	>
	"Remote" PathTear with destination IP address set to	<li>On D, there would be a remote signaling adjacency with
	that of the node D used in the Node-ID signaling adjacency with	B, and so D accepts the "Remote" PathTear and deletes the
	D,	PSB and RSB states corresponding to the LSP.</li>
	and the RSVP_HOP object containing local address used in the	</ol>
	Node-ID signaling adjacency.
	</t>
	</list>
	<list style="hanging">
	<t hangText="4.">B then deletes the PSB and RSB states corresponding to
	the LSP.
	</t>
	</list>
	<list style="hanging">
	<t hangText="5.">On D there would be a remote signaling adjacency with
	B and so D accepts the "Remote" PathTear and delete th
	e
	PSB and RSB states corresponding to the LSP.
	</t>
	</list>
	</t>


	<section anchor="lcl_repair_fail" title="PLR Behavior on Local Repair Failu	<section anchor="lcl_repair_fail">
	re">	<name>PLR Behavior on Local Repair Failure</name>
	<t>If local repair fails on the PLR after a failure, the PLR MUST send a	<t>If local repair fails on the PLR after a failure, the PLR <bcp14>MU
	"Remote" PathTear to the MP. The purpose of this is to clean	ST</bcp14> send a
	up LSP state from the PLR to the Egress. Upon receiving the PathTear,	"Remote" PathTear to the MP. The purpose of this is to clean
	the MP MUST delete the states corresponding to the LSP and also	up LSP state from the PLR to the egress. Upon receiving the PathTear,
	propagate the PathTear downstream thereby achieving state cleanup from	the MP <bcp14>MUST</bcp14> delete the states corresponding to the LSP
		and also
		propagate the PathTear downstream, thereby achieving state cleanup fro
		m
	all downstream nodes up to the LSP egress. Note that in the case of li nk	all downstream nodes up to the LSP egress. Note that in the case of li nk

	protection, the PathTear MUST be directed to the LP-MP's Node-ID IP	protection, the PathTear <bcp14>MUST</bcp14> be directed to the LP-MP'
	address rather than the Nhop interface address.	s Node-ID IP
	</t>	address rather than the NHOP interface address.
	</section>	</t>
		</section>
	<section anchor="resv_rro_chng" title="PLR Behavior on Resv RRO Change">	<section anchor="resv_rro_chng">
	<t>When a PLR router that has already made NP available for an LSP	<name>PLR Behavior on Resv RRO Change</name>
		<t>When a PLR router that has already made NP available for an LSP
	detects a change in the RRO carried in the Resv message that indicates	detects a change in the RRO carried in the Resv message that indicates
	that the router's former NP-MP is no longer present on the path of	that the router's former NP-MP is no longer present on the path of

	the LSP, then the router MUST send a "Remote" PathTear	the LSP, then the router <bcp14>MUST</bcp14> send a "Remote" PathTear
	directly to its former NP-MP.	directly to its former NP-MP.

	</t>	</t>
	<t>In the example topology <xref target="example_network"/>, assume node	<t>In the example topology in <xref target="example_network"/>, assume
		node
	A has made node protection available for an LSP and C has concluded it	A has made node protection available for an LSP and C has concluded it

	is the NP-MP for PLR A. When the B-C link fails then C, implementing t he	is the NP-MP for PLR A. When the B-C link fails, then C, implementing the
	procedure specified in <xref target="failures_lpnpmp"/> of this	procedure specified in <xref target="failures_lpnpmp"/> of this

	document, will retain the states corresponding to the LSP until: the	document, will retain the states corresponding to the LSP until one of
	remote Node-ID signaling adjacency with A goes down, or a PathTear or	the following occurs:</t>
	a ResvTear is received for its PSB or RSB respectively. If B also has	<ul>
	made node protection available, B will eventually complete backup LSP	<li>the remote Node-ID signaling adjacency with A goes down
	signaling with its NP-MP D and trigger a Resv to A with RRO changed.	or</li>
	The new RRO of the LSP carried in the Resv will not contain C. When A	<li>a PathTear or a ResvTear is received for its PSB or RSB,
	processes the Resv message with a new RRO not containing C - its forme	respectively.</li>
	r	</ul>
	NP-MP, A sends a "Remote" PathTear to C. When C receives	<t>If B also has made node protection available, B will eventually
	the "Remote" PathTear for its PSB state, C will send a norma	complete backup LSP signaling with its NP-MP D and trigger a Resv
	l	to A with RRO changed. The new RRO of the LSP carried in the Resv
	PathTear downstream to D and delete both the PSB and RSB states	will not contain C. When A processes the Resv message with a new
	corresponding to the LSP. As D has already received backup LSP	RRO not containing C, its former NP-MP, A, sends a "Remote"
	signaling from B, D will retain control plane and forwarding states	PathTear to C. When C receives the "Remote" PathTear for its PSB
	corresponding to the LSP.	state, C will send a normal PathTear downstream to D and delete
	</t>	both the PSB and RSB states corresponding to the LSP. As D has
	</section>	already received backup LSP signaling from B, D will retain the contro
		l
	<section anchor="lcl_repair_preempt" title="LSP Preemption during Local Rep	plane and forwarding states corresponding to the LSP.
	air">	</t>
	<section anchor="lcl_repair_preempt_lpnp" title="Preemption on LP-MP after	</section>
	Phop Link Failure">	<section anchor="lcl_repair_preempt">
	<t>If an LSP is preempted on an LP-MP after its Phop link has already	<name>LSP Preemption During Local Repair</name>
	failed but the backup LSP has not been signaled yet as part of local	<section anchor="lcl_repair_preempt_lpnp">
	repair procedure, then the node MUST send a normal PathTear and delete	<name>Preemption on LP-MP After PHOP Link Failure</name>
		<t>If an LSP is preempted on an LP-MP after its PHOP link has alread
		y
		failed but the backup LSP has not been signaled yet as part of the loc
		al
		repair procedure, then the node <bcp14>MUST</bcp14> send a normal Path
		Tear and delete
	both the PSB and RSB states corresponding to the LSP. As the LP-MP has	both the PSB and RSB states corresponding to the LSP. As the LP-MP has
	retained the LSP state expecting the PLR to initiate backup LSP signal ing,	retained the LSP state expecting the PLR to initiate backup LSP signal ing,

	preemption would bring down the LSP and the node would not be LP-MP an	preemption would bring down the LSP and the node would not be LP-MP an
	y	ymore, requiring the node to clean up the LSP state.
	more requiring the node to clean up the LSP state.	</t>
	</t>	</section>
	</section>


	<section anchor="lcl_repair_preempt_npmp" title="Preemption on NP-MP after	<section anchor="lcl_repair_preempt_npmp">
	Phop Link Failure">	<name>Preemption on NP-MP After PHOP Link Failure</name>
	<t>If an LSP is preempted on an NP-MP after its Phop link has already	<t>If an LSP is preempted on an NP-MP after its PHOP link has alread
		y
	failed but the backup LSP has not been signaled yet, then the node	failed but the backup LSP has not been signaled yet, then the node

	MUST send a normal PathTear and delete the PSB and RSB states	<bcp14>MUST</bcp14> send a normal PathTear and delete the PSB and RSB
	corresponding to the LSP. As the NP-MP has retained LSP state	states
		corresponding to the LSP. As the NP-MP has retained the LSP state
	expecting the PLR to initiate backup LSP signaling, preemption	expecting the PLR to initiate backup LSP signaling, preemption

	would bring down the LSP and the node would not be NP-MP any more	would bring down the LSP and the node would not be NP-MP anymore,
	requiring the node to clean up LSP state.	requiring the node to clean up LSP state.

	</t>	</t>
	<t>Consider that B-C link goes down on the same example topology	<t>Consider that the B-C link goes down on the same example topology
	(<xref target="example_network"/>). As C is the NP-MP for the PLR A, C	(<xref target="example_network"/>). As C is the NP-MP for the PLR A, C

	will retain LSP state.	will retain the LSP state.
	<list style="hanging">	</t>
	<t hangText="1.">The LSP is preempted on C.
	</t>	<ol>
	</list>	<li>The LSP is preempted on C.</li>
	<list style="hanging">	<li>C will delete the RSB state corresponding to the
	<t hangText="2.">C will delete the RSB state corresponding to the LSP.	LSP. However, C cannot send a PathErr or a ResvTear to the PLR A
	But C cannot send a PathErr or a ResvTear to the PLR A because	because the backup LSP has not been signaled yet.</li>
	the backup LSP has not been signaled yet.	<li>As the only reason for C having retained state after PHOP
	</t>	node failure was that it was an NP-MP, C sends a normal PathTear
	</list>	to D and also deletes its PSB state. D would also delete the PSB
	<list style="hanging">	and RSB states on receiving a PathTear from C.</li>
	<t hangText="3.">As the only reason for C having retained state after	<li>B starts backup LSP signaling to D. However, as D does not hav
	Phop node failure was that it was an NP-MP, C sends a normal	e
	PathTear to D and delete its PSB state also. D would also delete	the LSP state, it will reject the backup LSP Path message and send
	the	a
	PSB and RSB states on receiving a PathTear from C.	PathErr to B.</li>
	</t>	<li>B will delete its reservation and send a ResvTear to A.</li>
	</list>	</ol>
	<list style="hanging">	</section>
	<t hangText="4.">B starts backup LSP signaling to D. But as D does	</section>
	not have the LSP state, it will reject the backup LSP Path and
	send a PathErr to B.
	</t>
	</list>
	<list style="hanging">
	<t hangText="5.">B will delete its reservation and send a ResvTear to A.
	</t>
	</list>
	</t>
	</section>	</section>

	</section>
	</section>


	<section anchor="compatible" title="Backward Compatibility Procedures">	<section anchor="compatible">
	<t>"Refresh interval Independent FRR" or RI-RSVP-FRR refers to th	<name>Backward Compatibility Procedures</name>
	e	<t>"Refresh-Interval Independent RSVP-TE FRR" and "RI-RSVP-FRR" refer to
	set of procedures defined in this document to eliminate the reliance of	the
		set of procedures defined in this document to eliminate the reliance on
	periodic refreshes. The extensions proposed in RSVP-TE Summary FRR	periodic refreshes. The extensions proposed in RSVP-TE Summary FRR
	<xref target="RFC8796"/> may apply to implementations that do not support	<xref target="RFC8796"/> may apply to implementations that do not support
	RI-RSVP-FRR. On the other hand, RI-RSVP-FRR extensions relating to LSP	RI-RSVP-FRR. On the other hand, RI-RSVP-FRR extensions relating to LSP

	state cleanup namely Conditional and "Remote" PathTear require	state cleanup, namely Conditional and "Remote" PathTears, require
	support from one-hop and two-hop neighboring nodes along the LSP path.	support from one-hop and two-hop neighboring nodes along the LSP.
	So procedures that fall under LSP state cleanup category MUST NOT be	Thus, procedures that fall under the LSP state cleanup category <bcp14>MU
	turned on if any of the nodes involved in the node protection FRR i.e.	ST NOT</bcp14> be
	the PLR, the MP and the intermediate node in the case of NP, does not	turned on if any of the nodes involved in the node protection FRR (i.e.,
		the PLR, the MP, and the intermediate node in the case of NP) do not
	support RI-RSVP-FRR extensions. Note that for LSPs requesting link	support RI-RSVP-FRR extensions. Note that for LSPs requesting link

	protection, only the PLR and the LP-MP MUST support the extensions.	protection, only the PLR and the LP-MP <bcp14>MUST</bcp14> support the ex
	</t>	tensions.
	<section anchor="compat_detect" title="Detecting Support for Refresh interv	</t>
	al Independent FRR">
	<t>An implementation supporting RI-RSVP-FRR extensions MUST set the flag	<section anchor="compat_detect">
	"Refresh interval Independent RSVP" or RI-RSVP flag in the	<name>Detecting Support for Refresh-Interval Independent RSVP-TE FRR</
		name>
		<t>An implementation supporting RI-RSVP-FRR extensions <bcp14>MUST</bc
		p14> set the RI-RSVP Capable flag in the
	CAPABILITY object carried in Hello messages as specified in RSVP-TE	CAPABILITY object carried in Hello messages as specified in RSVP-TE
	Scaling Techniques <xref target="RFC8370"/>. If an implementation does	Scaling Techniques <xref target="RFC8370"/>. If an implementation does
	not set the flag even if it supports RI-RSVP-FRR extensions, then its	not set the flag even if it supports RI-RSVP-FRR extensions, then its
	neighbors will view the node as any node that does not support the	neighbors will view the node as any node that does not support the
	extensions.	extensions.

	<list style="hanging">	</t>
	<t hangText="-">As nodes supporting the RI-RSVP-FRR extensions initiate	<ul>
	Node-ID based signaling adjacency with all immediate neighbors,	<li>As nodes supporting the RI-RSVP-FRR extensions initiate
	such a node on the path of a protected LSP can determine whether	Node-ID-based signaling adjacency with all immediate neighbors,
	its Phop and Nhop neighbors support RI-RSVP-FRR enhancements.	such a node on the path of a protected LSP can determine whether
	</t>	its PHOP and NHOP neighbors support RI-RSVP-FRR enhancements.</li>
	</list>
	<list style="hanging">
	<t hangText="-">As nodes supporting the RI-RSVP-FRR extensions also initi
	ate
	Node-ID based signaling adjacency with the NNhop along the path of
	the LSP requested node protection (see <xref target="sig_plr_behav
	ior"/> of this document),
	each node along the LSP path can determine whether its NNhop node
	supports RI-RSVP-FRR enhancements. If the NNhop (a) does not reply
	to remote Node-ID Hello messages or (b) does not set the RI-RSVP f
	lag
	in the CAPABILITY object carried in its Node-ID Hello messages, th
	en
	the node acting as the PLR can conclude that NNhop does not suppor
	t
	RI-RSVP-FRR extensions.
	</t>
	</list>
	<list style="hanging">
	<t hangText="-">If node protection is requested for an LSP and if (a)
	the PPhop node has not included a matching B-SFRR-Ready Extended
	Association object in its Path messages or (b) the PPhop node has
	not initiated remote Node-ID Hello messages or (c) the PPhop node
	does not set the RI-RSVP flag in the CAPABILITY object carried
	in its Node-ID Hello messages, then the node MUST conclude
	that the PLR does not support RI-RSVP-FRR extensions.
	</t>
	</list>
	</t>
	</section>


	<section anchor="compat_procedures" title="Procedures for Backward Compatib	<li>As nodes supporting the RI-RSVP-FRR extensions also initiate
	ility">	Node-ID-based signaling adjacency with the NNHOP along the path of
	<t>Every node that supports RI-RSVP-FRR MUST support the procedures define	the LSP requesting node protection (see <xref
	d	target="sig_plr_behavior"/> of this document), each node along the
		LSP can determine whether its NNHOP node supports RI-RSVP-FRR
		enhancements. If the NNHOP (a) does not reply to remote Node-ID
		Hello messages or (b) does not set the RI-RSVP flag in the
		CAPABILITY object carried in its Node-ID Hello messages, then the
		node acting as the PLR can conclude that NNHOP does not support
		RI-RSVP-FRR extensions.</li>

		<li>If node protection is requested for an LSP and if (a) the
		PPHOP node has not included a matching B-SFRR-Ready Extended
		ASSOCIATION object in its Path messages, (b) the PPHOP node has
		not initiated remote Node-ID Hello messages, or (c) the PPHOP node
		does not set the RI-RSVP flag in the CAPABILITY object carried in
		its Node-ID Hello messages, then the node <bcp14>MUST</bcp14>
		conclude that the PLR does not support RI-RSVP-FRR
		extensions.</li>
		</ul>
		</section>

		<section anchor="compat_procedures">
		<name>Procedures for Backward Compatibility</name>

		<t>Every node that supports RI-RSVP-FRR <bcp14>MUST</bcp14> support th
		e procedures defined
	in this section in order to support backward compatibility for	in this section in order to support backward compatibility for

	those subset of LSPs that also traverse nodes that do not support	those subsets of LSPs that also traverse nodes that do not support
	RI-RSVP-FRR.	RI-RSVP-FRR.

	</t>	</t>
	<section anchor="dnstr_no_support" title="Lack of support on Downstream No
	de">
	<t>The procedures on the downstream direction are as follows.
	<list style="hanging">
	<t hangText="-">If a node finds that the Nhop node along the LSP does not
	support the RI-RSVP-FRR extensions, then the node MUST reduce
	the "refresh period" in the TIME_VALUES object carried
	in the Path messages to the default short refresh interval.
	</t>
	</list>
	<list style="hanging">
	<t hangText="-">If node protection is requested for the LSP and the NNhop
	node along the LSP path does not support the RI-RSVP-FRR extensio
	ns,
	then the node MUST reduce the "refresh period" in the
	TIME_VALUES object carried in the Path messages to the default sh
	ort
	refresh interval.
	</t>
	</list>
	</t>
	<t>If a node reduces the refresh time using the above procedures, it
	MUST NOT send any "Remote" PathTear or Conditional PathTear
	message to the downstream node.
	</t>
	<t>Consider the example topology in <xref target="example_network"/>.
	If C does not support the RI-RSVP-FRR extensions, then:
	<list style="hanging">
	<t hangText="-">A and B reduce the refresh time to the default
	short refresh interval of 30 seconds and trigger a Path message
	</t>
	</list>
	<list style="hanging">
	<t hangText="-">If B is not an MP and if Phop link of B fails, B
	cannot send Conditional PathTear to C but times out the PSB
	state from A normally. Note that B can time out the PSB state
	A normally only if A did not set long refresh in the TIME_VALUES
	object carried in the Path messages sent earlier.
	</t>
	</list>
	</t>
	</section>


	<section anchor="upstr_no_support" title="Lack of support on Upstream Node	<section anchor="dnstr_no_support">
	">	<name>Lack of Support on Downstream Nodes</name>
	<t>The procedures are as follows.
	<list style="hanging">
	<t hangText="-">If a node finds that the Phop node along the LSP path doe
	s
	not support the RI-RSVP-FRR extensions, then the node MUST reduce
	the "refresh period" in the TIME_VALUES object carried
	in
	the Resv messages to the default short refresh interval.
	</t>
	</list>
	<list style="hanging">
	<t hangText="-">If node protection is requested for the LSP and the Phop
	node along the LSP path does not support the RI-RSVP-FRR
	extensions, then the node MUST reduce the "refresh
	period" in the TIME_VALUES object carried in the Path
	messages to the default short refresh interval (thus, the Nhop
	can use compatible values when sending a Resv).
	</t>
	</list>
	<list style="hanging">
	<t hangText="-">If node protection is requested for the LSP and the
	PPhop node does not support the RI-RSVP-FRR extensions, then
	the node MUST reduce the "refresh period" in the
	TIME_VALUES object carried in the Resv messages to the default
	short refresh interval.
	</t>
	</list>
	<list style="hanging">
	<t hangText="-">If the node reduces the refresh time using the above
	procedures, it MUST NOT execute MP procedures specified in
	<xref target="failures"/> of this document.
	</t>
	</list>
	</t>
	</section>


	<section anchor="incr_deploy" title="Incremental Deployment">	<t>The procedures on the downstream direction are as follows:</t>
	<t>The backward compatibility procedures described in the previous	<ul>
	sub-sections imply that a router supporting the RI-RSVP-FRR	<li>If a node finds that the NHOP node along the LSP does not
		support the RI-RSVP-FRR extensions, then the node
		<bcp14>MUST</bcp14> reduce the "refresh period" in the
		TIME_VALUES object carried in the Path messages to the default
		short refresh interval.</li>
		<li>If node protection is requested for the LSP and the NNHOP
		node along the LSP does not support the RI-RSVP-FRR
		extensions, then the node <bcp14>MUST</bcp14> reduce the
		"refresh period" in the TIME_VALUES object carried in the Path
		messages to the default short refresh interval.</li>
		</ul>

		<t>If a node reduces the refresh time using the above procedures,
		it <bcp14>MUST NOT</bcp14> send any "Remote" PathTear or
		Conditional PathTear message to the downstream node.</t>

		<t>Consider the example topology in <xref
		target="example_network"/>. If C does not support the RI-RSVP-FRR
		extensions, then:</t>

		<ul>
		<li>A and B reduce the refresh time to the default short
		refresh interval of 30 seconds and trigger a Path message.</li>

		<li>If B is not an MP and if the PHOP link of B fails, B cannot
		send a Conditional PathTear to C but times out the PSB state
		from A normally. Note that B can only normally time out the PSB s
		tate A
		if A did not set the long refresh in the TIME_VALUES
		object carried in the Path messages sent earlier.</li>
		</ul>
		</section>

		<section anchor="upstr_no_support">
		<name>Lack of Support on Upstream Nodes</name>

		<t>The procedures on the upstream direction are as follows:</t>

		<ul>
		<li>If a node finds that the PHOP node along the LSP does
		not support the RI-RSVP-FRR extensions, then the node
		<bcp14>MUST</bcp14> reduce the "refresh period" in the
		TIME_VALUES object carried in the Resv messages to the default
		short refresh interval.</li>

		<li>If node protection is requested for the LSP and the PHOP
		node along the LSP does not support the RI-RSVP-FRR
		extensions, then the node <bcp14>MUST</bcp14> reduce the
		"refresh period" in the TIME_VALUES object carried in the Path
		messages to the default short refresh interval (thus, the NHOP
		can use compatible values when sending a Resv).</li>

		<li>If node protection is requested for the LSP and the PPHOP
		node does not support the RI-RSVP-FRR extensions, then the node
		<bcp14>MUST</bcp14> reduce the "refresh period" in the
		TIME_VALUES object carried in the Resv messages to the default
		short refresh interval.</li>

		<li>If the node reduces the refresh time using the above
		procedures, it <bcp14>MUST NOT</bcp14> execute MP procedures
		specified in <xref target="failures"/> of this document.</li>
		</ul>
		</section>

		<section anchor="incr_deploy">
		<name>Incremental Deployment</name>

		<t>The backward compatibility procedures described in the previous
		subsections imply that a router supporting the RI-RSVP-FRR
	extensions specified in this document can apply the procedures	extensions specified in this document can apply the procedures

	specified in the document either in the downstream or upstream	specified in this document either in the downstream or upstream
	direction of an LSP, depending on the capability of the routers	direction of an LSP, depending on the capability of the routers

	downstream or upstream in the LSP path.	downstream or upstream in the LSP.
	<list style="hanging">	</t>
	<t hangText="-">RI-RSVP-FRR extensions and procedures are enabled for
	downstream Path, PathTear and ResvErr messages corresponding	<ul>
		<li>RI-RSVP-FRR extensions and procedures are enabled for
		downstream Path, PathTear, and ResvErr messages corresponding
	to an LSP if link protection is requested for the LSP and the	to an LSP if link protection is requested for the LSP and the

	Nhop node supports the extensions	NHOP node supports the extensions.</li>
	</t>
	</list>	<li>RI-RSVP-FRR extensions and procedures are enabled for
	<list style="hanging">	downstream Path, PathTear, and ResvErr messages corresponding
	<t hangText="-">RI-RSVP-FRR extensions and procedures are enabled for
	downstream Path, PathTear and ResvErr messages corresponding
	to an LSP if node protection is requested for the LSP and both	to an LSP if node protection is requested for the LSP and both

	Nhop & NNhop nodes support the extensions	NHOP and NNHOP nodes support the extensions.</li>
	</t>
	</list>	<li>RI-RSVP-FRR extensions and procedures are enabled for
	<list style="hanging">	upstream PathErr, Resv, and ResvTear messages corresponding to an
	<t hangText="-">RI-RSVP-FRR extensions and procedures are enabled for	LSP if link protection is requested for the LSP and the PHOP
	upstream PathErr, Resv and ResvTear messages corresponding to	node supports the extensions.</li>
	an LSP if link protection is requested for the LSP and the
	Phop node supports the extensions	<li>RI-RSVP-FRR extensions and procedures are enabled for
	</t>	upstream PathErr, Resv, and ResvTear messages corresponding to an
	</list>	LSP if node protection is requested for the LSP and both PHOP
	<list style="hanging">	and PPHOP nodes support the extensions.</li>
	<t hangText="-">RI-RSVP-FRR extensions and procedures are enabled for	</ul>
	upstream PathErr, Resv and ResvTear messages corresponding to
	an LSP if node protection is requested for the LSP and both	<t>For example, if an implementation supporting the RI-RSVP-FRR
	Phop and the PPhop support the extensions	extensions specified in this document is deployed on all routers in a
	</t>
	</list>
	</t>
	<t>For example, if an implementation supporting the RI-RSVP-FRR
	extensions specified in this document is deployed on all routers in
	particular region of the network and if all the LSPs in the network	particular region of the network and if all the LSPs in the network
	request node protection, then the FRR extensions will only be	request node protection, then the FRR extensions will only be
	applied for the LSP segments that traverse the particular region.	applied for the LSP segments that traverse the particular region.
	This will aid incremental deployment of these extensions and also	This will aid incremental deployment of these extensions and also
	allow reaping the benefits of the extensions in portions of the	allow reaping the benefits of the extensions in portions of the
	network where it is supported.	network where it is supported.

	</t>	</t>
		</section>
		</section>
	</section>	</section>

	</section>	<section anchor="cap_bit_without_support">
	</section>	<name>Consequences of Advertising RI-RSVP Without RI-RSVP-FRR</name>
		<t>If a node supporting facility backup protection <xref target="RFC4090
	<section anchor="cap_bit_without_support" title="Consequence of Advertisin	"/>
	g RI-RSVP without RI-RSVP-FRR">	sets the RI-RSVP capability (I-bit) but does not support the RI-RSVP-FR
	<t>If a node supporting facility backup protection <xref target="RFC4090"	R
	/>
	sets the RI-RSVP capability (I bit) but does not support the RI-RSVP-FR
	R
	extensions, due to an implementation bug or configuration error, then it	extensions, due to an implementation bug or configuration error, then it

	leaves room for stale state to linger around for an inordinate period	leaves room for the stale state to linger around for an inordinate per
	of	iod of
	time or disruption of normal FRR operation	time or for disruption of normal FRR operations
	(see <xref target="prob_desc"/> of this document). Consider the example	(see <xref target="prob_desc"/> of this document). Consider the example

	topology <xref target="example_network"/> provided in this document.	topology (<xref target="example_network"/>) provided in this document.
	<list style="hanging">	</t>
	<t hangText="-">Assume node B does set RI-RSVP capability in its Node-ID
	based Hello messages even though it does not support RI-RSVP-FRR
	extensions. When B detects the failure of its Phop link along an
	LSP, it will not send Conditional PathTear to C as required by
	the RI-RSVP-FRR procedures. If B simply leaves the LSP state
	without deleting, then B may end up holding on to the stale state
	until the (long) refresh timeout.
	</t>
	</list>
	<list style="hanging">
	<t hangText="-">Instead of node B, assume node C does set RI-RSVP
	capability in its Node-id based Hello messages even though it
	does not support RI-RSVP-FRR extensions. When B details the
	failure of its Phop link along an LSP, it will send Conditional
	PathTear to C as required by the RI-RSVP-FRR procedures. But,
	C would not recognize the condition encoded in the PathTear and
	end up tearing down the LSP.
	</t>
	</list>
	<list style="hanging">
	<t hangText="-">Assume node B does set RI-RSVP capability in its Node-ID
	based Hello messages even though it does not support RI-RSVP-FRR
	extensions. Also assume local repair is about to commence on node
	B for an LSP that has only requested link protection. That is,
	B has not initiated the backup LSP signaling for the LSP. If node
	B
	receives a normal PathTear at this time from ingress A because of
	a
	management event initiated on A, then B simply deletes the LSP
	state without sending a Remote PathTear to the LP-MP C. So, C
	may end up holding on to the stale state until the (long) refresh
	timeout.
	</t>
	</list>
	</t>
	</section>


	</section>	<ul>
		<li>Assume node B does set the RI-RSVP capability in its Node-ID-based
		Hello messages even though it does not support RI-RSVP-FRR
		extensions. When B detects the failure of its PHOP link along an
		LSP, it will not send a Conditional PathTear to C as required by the
		RI-RSVP-FRR procedures. If B simply leaves the LSP state without
		deleting, then B may end up holding on to the stale state until the
		(long) refresh timeout.</li>


	<section anchor="Security" title="Security Considerations">	<li>Instead of node B, assume node C does set the RI-RSVP capability i
		n
		its Node-ID-based Hello messages even though it does not support
		RI-RSVP-FRR extensions. When B details the failure of its PHOP link
		along an LSP, it will send a Conditional PathTear to C as required by
		the RI-RSVP-FRR procedures. However, C would not recognize the conditi
		on
		encoded in the PathTear and end up tearing down the LSP.</li>

		<li>Assume node B does set the RI-RSVP capability in its Node-ID-based
		Hello messages even though it does not support RI-RSVP-FRR
		extensions. In addition, assume local repair is about to commence on n
		ode B
		for an LSP that has only requested link protection, that is, B has
		not initiated the backup LSP signaling for the LSP. If node B
		receives a normal PathTear at this time from ingress A because of a
		management event initiated on A, then B simply deletes the LSP state
		without sending a Remote PathTear to the LP-MP C, so C may end up
		holding on to the stale state until the (long) refresh timeout.</li>
		</ul>
		</section>
		</section>

		<section anchor="Security">
		<name>Security Considerations</name>
	<t>The security considerations pertaining to the original RSVP protocol	<t>The security considerations pertaining to the original RSVP protocol

	<xref target="RFC2205"/>, <xref target="RFC3209"/> and <xref target="RF	(<xref target="RFC2205"/>, <xref target="RFC3209"/>, and <xref target="
	C5920"/>	RFC5920"/>)
	remain relevant. When using RSVP Cryptographic Authentication	remain relevant. When using RSVP cryptographic authentication
	<xref target="RFC2747"/>, more robust algorithms such as HMAC-SHA256,	<xref target="RFC2747"/>, more robust algorithms such as HMAC-SHA256,

	HMAC-SHA384, or HMAC-SHA512 <xref target="RFC2104"/><xref target="FIPS-1	HMAC-SHA384, or HMAC-SHA512 <xref target="RFC2104"/> <xref target="FIPS-
	80-4"/>	180-4"/>
	SHOULD be used when computing the keyed message digest where possible.	<bcp14>SHOULD</bcp14> be used when computing the keyed message digest wh
		ere possible.
	</t>	</t>


	<t>This document extends the applicability of Node-ID based Hello session	<t>This document extends the applicability of Node-ID-based Hello
	between immediate neighbors. The Node-ID based Hello session between the P	sessions between immediate neighbors. The Node-ID-based Hello session
	LR	between the PLR and the NP-MP may require the two routers to exchange
	and the NP-MP may require the two routers to exchange Hello messages with	Hello messages with a non-immediate neighbor. Therefore, the
	non-immediate neighbor. So, the implementations SHOULD provide the	implementations <bcp14>SHOULD</bcp14> provide the option to configure eith
	option to configure Node-ID neighbor specific or global authentication	er a
	key to authentication messages received from Node-ID neighbors. The	specific neighbor or global Node-ID authentication key to authentication
	network administrator SHOULD utilize this option to enable RSVP-TE routers	messages received from Node-ID neighbors. The network administrator
	to authenticate Node-ID Hello messages received with TTL greater than 1.	<bcp14>SHOULD</bcp14> utilize this option to enable RSVP-TE routers to
	Implementations SHOULD also provide the option to specify a limit on the	authenticate Node-ID Hello messages received with a TTL greater than 1.
	number of Node-ID based Hello sessions that can be established on a	Implementations <bcp14>SHOULD</bcp14> also provide the option to specify
	router supporting the extensions defined in this document.	a limit on the number of Node-ID-based Hello sessions that can be
		established on a router supporting the extensions defined in this
		document.
	</t>	</t>

	</section>	</section>


	<section anchor="IANA" title="IANA Considerations">	<section anchor="IANA">
	<section anchor="IANA_Conditions" title="CONDITIONS Object">	<name>IANA Considerations</name>
	<t>IANA maintains the Class Names, Class Numbers, and Class Types registr	<section anchor="IANA_Conditions">
	ies	<name>CONDITIONS Object</name>
	in the "RSVP parameters" registry group (see	<t>IANA maintains the "Class Names, Class Numbers, and Class Types" regi
	http://www.iana.org/assignments/rsvp-parameters/rsvp-parameters.xml).	stry
	IANA is requested to extend these registries by adding a new Class Num	in the "RSVP Parameters" registry group (see
	ber	<eref target="http://www.iana.org/assignments/rsvp-parameters/"/>).
	(in the 10bbbbbb range) and assign a new C-Type under this Class Numbe	IANA has extended these registries by adding a new Class Number
	r,	(in the 10bbbbbb range) and assigning a new C-Type under this Class Nu
		mber,
	as described below (see <xref target="cnd_path_tear_obj"/>):	as described below (see <xref target="cnd_path_tear_obj"/>):

		</t>


	<artwork>	<table anchor="table1">
	<![CDATA[	<name>Class Names, Class Numbers, and Class Types</name>
	Class Number Class Name Reference	<thead>
	TBA1 CONDITIONS This document	<tr>
	]]>	<th>Class Number</th>
	</artwork>	<th>Class Name</th>
		<th>Reference</th>
	<t>Class Type of C-types - TBA1 CONDITIONS </t>	</tr>
		</thead>
		<tbody>
		<tr>
		<td>135</td>
		<td>CONDITIONS</td>
		<td>RFC 9705</td>
		</tr>
		</tbody>
		</table>


	<artwork>	<table anchor="table2">
	<![CDATA[	<name>Class Type or C-Types - 135 CONDITIONS</name>
	Value Class Name Reference	<thead>
	1 CONDITIONS This document	<tr>
	]]>	<th>Value</th>
	</artwork>	<th>Description</th>
		<th>Reference</th>
		</tr>
		</thead>
		<tbody>
		<tr>
		<td>1</td>
		<td>CONDITIONS</td>
		<td>RFC 9705</td>
		</tr>
		</tbody>
		</table>
		<t>IANA has added a subregistry called "CONDITIONS Object
		Flags" as shown below. Assignments of additional Class Type values
		for Class Name "CONDITIONS" are to be performed via
		"IETF Review" <xref target="RFC8126"/>.</t>


	<t>IANA is requested to add a new sub-registry for "CONDITIONS Objec	<table anchor="table3">
	t	<name>CONDITIONS Object Flags</name>
	Flags" as shown below. Assignments of additional Class Type values	<thead>
	for Class Name "CONDITIONS" are to be performed via	<tr>
	"IETF Review" <xref target="RFC8126"/>.</t>	<th>Bit Number</th>
		<th>32-Bit Value</th>
		<th>Name</th>
		<th>Reference</th>
		</tr>
		</thead>
		<tbody>
		<tr>
		<td>0-30</td>
		<td></td>
		<td>Unassigned</td>
		<td></td>
		</tr>
		<tr>
		<td>31</td>
		<td>0x0001</td>
		<td>Merge-point</td>
		<td>RFC 9705</td>
		</tr>
		</tbody>
		</table>


	<artwork>	<t>All assignments in this subregistry are to be performed via "IETF
	<![CDATA[	Review" <xref target="RFC8126"/>.</t>
	Bit Number 32-bit Value Name Reference
	0-30 Unassigned
	31 0x0001 Merge-point This document
	]]>
	</artwork>


	<t>All assignments in this sub-registry are to be performed via	</section>
	"IETF Review" <xref target="RFC8126"/>.</t>
	</t>
	</section>	</section>

	</section>

	<!-- This PI places the pagebreak correctly (before the section title) in the
	text output. -->

	<?rfc needLines="8" ?>


	<section anchor="Acknowledgements" title="Acknowledgements">	</middle>
	<t>We are very grateful to Yakov Rekhter for his contributions to the	<back>
	development of the idea and thorough review of content of the draft.
	We are thankful to Raveendra Torvi and Yimin Shen for their comments
	and inputs on early versions of the draft. We also thank Alexander
	Okonnikov for his review and comments on the draft.
	</t>
	</section>


	<!-- Possibly a 'Contributors' section ... -->	<references>
		<name>References</name>
		<references>
		<name>Normative References</name>


	<section anchor="Contributors" title="Contributors">	<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.2
	<t>	119.xml"/>
	Markus Jork<br></br>	<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.2
	Juniper Networks, Inc.<br></br>	747.xml"/>
	Email: mjork@juniper.net	<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.3
	</t>	209.xml"/>
		<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.4
		090.xml"/>
		<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.2
		961.xml"/>
		<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.2
		205.xml"/>
		<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.4
		558.xml"/>
		<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.3
		473.xml"/>
		<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.5
		063.xml"/>
		<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8
		126.xml"/>
		<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8
		174.xml"/>
		<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8
		370.xml"/>
		<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8
		796.xml"/>
		</references>


	<t>	<references>
	Harish Sitaraman<br></br>	<name>Informative References</name>
	Individual Contributor<br></br>
	Email: harish.ietf@gmail.com
	</t>


	<t>	<reference anchor="FIPS-180-4" target="https://nvlpubs.nist.gov/nistpubs
	Vishnu Pavan Beeram<br></br>	/FIPS/NIST.FIPS.180-4.pdf">
	Juniper Networks, Inc.<br></br>	<front>
	Email: vbeeram@juniper.net	<title>Secure Hash Standard</title>
	</t>	<author>
		<organization>National Institute of Standards and Technology</orga
		nization>
		</author>
		<date month="August" year="2015"/>
		</front>
		<seriesInfo name="FIPS PUB" value="180-4"/>
		<seriesInfo name="DOI" value="10.6028/NIST.FIPS.180-4"/>
		</reference>


	<t>	<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.2
	Ebben Aries<br></br>	104.xml"/>
	Juniper Networks, Inc.<br></br>	<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.5
	Email: exa@juniper.com	920.xml"/>
	</t>


	<t>	</references>
	Mike Taillon<br></br>	</references>
	Cisco Systems, Inc.<br></br>
	Email: mtaillon@cisco.com
	</t>


	</section>	<section anchor="Acknowledgements" numbered="false">
		<name>Acknowledgements</name>
		<t>We are very grateful to <contact fullname="Yakov Rekhter"/> for his
		contributions to the development of the idea and thorough review of the
		content of the document. We are thankful to <contact fullname="Raveendra
		Torvi"/> and <contact fullname="Yimin Shen"/> for their comments and
		inputs on early versions of the document. We also thank <contact
		fullname="Alexander Okonnikov"/> for his review and comments on the
		document.
		</t>
		</section>


	</middle>	<section anchor="Contributors" numbered="false">
		<name>Contributors</name>


	<back>	<contact fullname="Markus Jork">
	<!-- References split into informative and normative -->	<organization>Juniper Networks, Inc.</organization>
		<address>
		<email>mjork@juniper.net</email>
		</address>
		</contact>


	<!-- There are 2 ways to insert reference entries from the citation libraries	<contact fullname="Harish Sitaraman">
	:	<organization>Individual Contributor</organization>
	1. define an ENTITY at the top, and use "ampersand character"RFC2629; here (	<address>
	as shown)	<email>harish.ietf@gmail.com</email>
	2. simply use a PI "less than character"?rfc include="reference.RFC.2119.xml	</address>
	"?> here	</contact>
	(for I-Ds: include="reference.I-D.narten-iana-considerations-rfc2434bis.x
	ml")


	Both are cited textually in the same manner: by using xref elements.	<contact fullname="Vishnu Pavan Beeram">
	If you use the PI option, xml2rfc will, by default, try to find included fil	<organization>Juniper Networks, Inc.</organization>
	es in the same	<address>
	directory as the including file. You can also define the XML_LIBRARY environ	<email>vbeeram@juniper.net</email>
	ment variable	</address>
	with a value containing a set of directories to search. These can be either	</contact>
	in the local
	filing system or remote ones accessed by http (http://domain/dir/... ).-->


	<references title="Normative References">	<contact fullname="Ebben Aries">
	&RFC2119;	<organization>Juniper Networks, Inc.</organization>
	&RFC2747;	<address>
	&RFC3209;	<email>exa@juniper.com</email>
	&RFC4090;	</address>
	&RFC2961;	</contact>
	&RFC2205;
	&RFC4558;
	&RFC3473;
	&RFC5063;
	&RFC8126;
	&RFC8174;
	&RFC8370;
	&RFC8796;
	</references>


	<references title="Informative References">	<contact fullname="Mike Taillon">
	<reference anchor="FIPS-180-4">	<organization>Cisco Systems, Inc.</organization>
	<front>	<address>
	<title>Secure Hash Standard</title>	<postal/>
	<author>	<email>mtaillon@cisco.com</email>
	<organization>National Institute of Standards and Technology</organizati	</address>
	on>	</contact>
	</author>	</section>
	<date month="August" year="2015"/>
	</front>
	<seriesInfo name="FIPS" value="180-4"/>
	</reference>
	&RFC2104;
	&RFC5920;
	</references>


	</back>	</back>
	</rfc>	</rfc>

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