rfc9863v1.txt		rfc9863.txt
	skipping to change at line 61 ¶		skipping to change at line 61 ¶
	Trust Legal Provisions and are provided without warranty as described		Trust Legal Provisions and are provided without warranty as described
	in the Revised BSD License.		in the Revised BSD License.
	Table of Contents		Table of Contents
	1. Introduction		1. Introduction
	1.1. Requirements Language		1.1. Requirements Language
	2. Protocol Operation		2. Protocol Operation
	3. Protocol Extensions		3. Protocol Extensions
	3.1. Color Capability		3.1. Color Capability
	3.2. Color TLV		3.2. COLOR TLV
	4. Security Considerations		4. Security Considerations
	5. Manageability Considerations		5. Manageability Considerations
	5.1. Control of Function through Configuration and Policy		5.1. Control of Function through Configuration and Policy
	5.2. Information and Data Models		5.2. Information and Data Models
	5.3. Liveness Detection and Monitoring		5.3. Liveness Detection and Monitoring
	5.4. Verifying Correct Operation		5.4. Verifying Correct Operation
	5.5. Requirements on Other Protocols		5.5. Requirements on Other Protocols
	5.6. Impact on Network Operation		5.6. Impact on Network Operation
	6. IANA Considerations		6. IANA Considerations
	6.1. PCEP TLV Type Indicator		6.1. PCEP TLV Type Indicator
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	6.4. LSP-ERROR-CODE TLV Error Code Field		6.4. LSP-ERROR-CODE TLV Error Code Field
	7. References		7. References
	7.1. Normative References		7.1. Normative References
	7.2. Informative References		7.2. Informative References
	Acknowledgments		Acknowledgments
	Contributors		Contributors
	Authors' Addresses		Authors' Addresses
	1. Introduction		1. Introduction
	A Traffic Engineering (TE) tunnel [RFC3209] or Segment Routing (SR)		A Traffic Engineering (TE) Tunnel [RFC3209] or Segment Routing (SR)
	policy [RFC9256] can be associated with an intent or objective (e.g.,		policy [RFC9256] can be associated with an intent or objective (e.g.,
	low latency) by tagging it with a color. This color attribute is		low latency) by tagging it with a color. This color attribute is
	used as a guiding criterion for mapping services onto the TE tunnel		used as a guiding criterion for mapping services onto the TE Tunnel
	[RFC9012] or SR policy [RFC9256]. The term "color" used in this		[RFC9012] or SR Policy [RFC9256]. The term "color" used in this
	document must not be interpreted as the "thread color" specified in		document must not be interpreted as the "thread color" specified in
	[RFC3063] or the "resource color" (also referred to as "link color")		[RFC3063] or the "resource color" (also referred to as "link color")
	specified in [RFC3630], [RFC5329], [RFC5305], and [RFC7308].		specified in [RFC3630], [RFC5329], [RFC5305], and [RFC7308].
	[RFC8231] specifies extensions to the Path Computation Element		[RFC8231] specifies extensions to the Path Computation Element
	Protocol (PCEP) that enable the deployment of a stateful Path		Protocol (PCEP) that enable the deployment of a stateful Path
	Computation Element (PCE) model. These extensions allow a Path		Computation Element (PCE) model. These extensions allow a Path
	Computation Client (PCC) to delegate control of the Label Switched		Computation Client (PCC) to delegate control of the Label Switched
	Paths (LSPs) associated with its TE Tunnels to a stateful PCE.		Paths (LSPs) associated with its TE Tunnels to a stateful PCE.
	[RFC8281] specifies extensions that allow a PCE to instantiate and		[RFC8281] specifies extensions that allow a PCE to instantiate and
	skipping to change at line 110 ¶		skipping to change at line 110 ¶
	[RFC8664] specifies extensions that enable stateful control of SR		[RFC8664] specifies extensions that enable stateful control of SR
	paths via PCEP.		paths via PCEP.
	This document introduces extensions to PCEP to allow a color tag to		This document introduces extensions to PCEP to allow a color tag to
	be assigned to any TE path operated under a stateful PCE model		be assigned to any TE path operated under a stateful PCE model
	(including those set up using RSVP-TE [RFC8408] or Segment Routing		(including those set up using RSVP-TE [RFC8408] or Segment Routing
	[RFC8664]). The only exception where the extensions defined in this		[RFC8664]). The only exception where the extensions defined in this
	document MUST NOT be used to carry the color attribute is for SR		document MUST NOT be used to carry the color attribute is for SR
	paths established using the extensions defined in [RFC9862]. For		paths established using the extensions defined in [RFC9862]. For
	these SR paths, the associated color is already included as part of		these SR paths, the associated color is already included as part of
	the SR policy identifier encoding.		the SR Policy identifier encoding.
	The mechanism employed by the PCC for mapping services onto a TE path		The mechanism employed by the PCC for mapping services onto a TE path
	associated with a color attribute is outside the scope of this		associated with a color attribute is outside the scope of this
	document, as is any other use of the color tag.		document, as is any other use of the color tag.
	1.1. Requirements Language		1.1. Requirements Language
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and		"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
	"OPTIONAL" in this document are to be interpreted as described in		"OPTIONAL" in this document are to be interpreted as described in
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	2. Protocol Operation		2. Protocol Operation
	When the PCEP session is created, a PCEP (PCE/PCC) speaker sends an		When the PCEP session is created, a PCEP (PCE/PCC) speaker sends an
	Open message with an OPEN object that contains the STATEFUL-PCE-		Open message with an OPEN object that contains the STATEFUL-PCE-
	CAPABILITY TLV, as defined in [RFC8231]. A STATEFUL-PCE-CAPABILITY		CAPABILITY TLV, as defined in [RFC8231]. A STATEFUL-PCE-CAPABILITY
	TLV Flag (see Section 3.1) is introduced in this document to enable		TLV Flag (see Section 3.1) is introduced in this document to enable
	the PCEP speaker to advertise color capability.		the PCEP speaker to advertise color capability.
	In PCRpt, PCUpd, and PCInitiate messages, the LSP object [RFC8231]		In PCRpt, PCUpd, and PCInitiate messages, the LSP object [RFC8231]
	[RFC8281] is a mandatory inclusion and is used to carry information		[RFC8281] is a mandatory inclusion and is used to carry information
	specific to the target LSP. A TLV called the Color TLV (see		specific to the target LSP. A TLV called the COLOR TLV (see
	Section 3.2), which MAY be carried in the LSP object, is introduced		Section 3.2), which MAY be carried in the LSP object, is introduced
	in this document to carry the color attribute associated with the		in this document to carry the color attribute associated with the
	LSP. Only one COLOR TLV SHOULD be included in the LSP object. If		LSP. Only one COLOR TLV SHOULD be included in the LSP object. If
	the COLOR TLV appears in the LSP object more than once, only the		the COLOR TLV appears in the LSP object more than once, only the
	first occurrence is processed, and any others MUST be ignored.		first occurrence is processed, and any others MUST be ignored.
	A PCEP speaker that has advertised color capability MUST NOT send		A PCEP speaker that has advertised color capability MUST NOT send
	Color TLV encoded in the LSP object to a PCEP Peer that has not		COLOR TLV encoded in the LSP object to a PCEP Peer [RFC5440] that has
	advertised color capability. A PCEP speaker that advertises both		not advertised color capability. A PCEP speaker that advertises both
	color capability and SR Policy Association [RFC9862] capability MUST		color capability and SR Policy Association [RFC9862] capability MUST
	NOT send Color TLV encoded in the LSP object for SR Paths. The Color		NOT send COLOR TLV encoded in the LSP object for SR Paths. The COLOR
	TLV is ignored if it shows up in the LSP object of a message that		TLV is ignored if it shows up in the LSP object of a message that
	carries an ASSOCIATION object of type SR Policy Association		carries an ASSOCIATION object of type SR Policy Association
	[RFC9862]. The color encoded in the SR Policy Association takes		[RFC9862]. The color encoded in the SR Policy Association takes
	precedence in such a scenario.		precedence in such a scenario.
	If a PCC is unable to honor a color value passed in a PCUpd or a		If a PCC is unable to honor a color value passed in a PCUpd or a
	PCInitiate message, the PCC MUST reject the message and send a PCErr		PCInitiate message, the PCC MUST reject the message and send a PCErr
	message with Error-Type=19 (Invalid Operation) and Error-value=31		message with Error-Type=19 (Invalid Operation) and Error-value=31
	(Invalid color). This is expected behavior in scenarios where a PCC		(Invalid color). This is expected behavior in scenarios where a PCC
	implementation does not support a color value of zero for specific		implementation does not support a color value of zero for specific
	path setup types, and it receives that value in the COLOR TLV of a		path setup types, and it receives that value in the COLOR TLV of a
	PCUpd or a PCInitiate message.		PCUpd or a PCInitiate message.
	When LSPs that belong to the same TE tunnel are within the same Path		When LSPs that belong to the same TE Tunnel are within the same Path
	Protection Association Group [RFC8745], they are all expected to have		Protection Association Group [RFC8745], they are all expected to have
	the same color attached to them. If a PCEP speaker determines		the same color attached to them. If a PCEP speaker determines
	inconsistency in the color associated with the LSPs belonging to the		inconsistency in the color associated with the LSPs belonging to the
	same Path Protection Association Group, it MUST reject the message		same Path Protection Association Group, it MUST reject the message
	carrying the inconsistent color and send a PCErr message with Error-		carrying the inconsistent color and send a PCErr message with Error-
	Type=19 (Invalid Operation) and Error-value=32 (Inconsistent color).		Type=19 (Invalid Operation) and Error-value=32 (Inconsistent color).
	3. Protocol Extensions		3. Protocol Extensions
	3.1. Color Capability		3.1. Color Capability
	Section 7.1.1 of [RFC8231] defines STATEFUL-PCE-CAPABILITY TLV flags.		Section 7.1.1 of [RFC8231] defines STATEFUL-PCE-CAPABILITY TLV flags.
	The following flag is used to indicate if the speaker supports color		The following flag is used to indicate if the speaker supports color
	capability:		capability:
	C-bit (Bit 20): A PCE/PCC indicates that it supports the color		C-bit (Bit 20): A PCE/PCC indicates that it supports the color
	capability defined in this document by setting this bit.		capability defined in this document by setting this bit.
	3.2. Color TLV		3.2. COLOR TLV
	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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Type | Length=4 |		| Type | Length=4 |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Color |		| Color |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Figure 1: Color TLV		Figure 1: COLOR TLV
	Type has the value 67. Length carries a value of 4. The "Color"		Type: 67
	field is 4 bytes long and carries the actual color value (specified
	as an unsigned integer). A Color value of zero is allowed.		Length: 4
			Color: 4-byte field that carries the actual color value (specified
			as an unsigned integer). A value of zero is allowed.
	4. Security Considerations		4. Security Considerations
	This document defines a TLV for color and a flag for color capability		This document defines a TLV for color and a flag for color capability
	negotiation, which do not add any security concerns beyond those		negotiation, which do not add any security concerns beyond those
	discussed in [RFC5440], [RFC8231], and [RFC8281].		discussed in [RFC5440], [RFC8231], and [RFC8281].
	An unauthorized PCE may maliciously associate the LSP with an		An unauthorized PCE may maliciously associate the LSP with an
	incorrect color. The procedures described in [RFC8253] and [RFC9325]		incorrect color. The procedures described in [RFC8253] and [RFC9325]
	can be used to protect against this attack.		can be used to protect against this attack.
	skipping to change at line 221 ¶		skipping to change at line 224 ¶
	(Section 3.1). An implementation supporting this document SHOULD		(Section 3.1). An implementation supporting this document SHOULD
	allow the configuration of color assignment to a TE Tunnel or an SR		allow the configuration of color assignment to a TE Tunnel or an SR
	Policy. A PCC MAY have a local policy configuration that specifies		Policy. A PCC MAY have a local policy configuration that specifies
	how the color tag is used. This policy configuration is outside the		how the color tag is used. This policy configuration is outside the
	scope of this document.		scope of this document.
	5.2. Information and Data Models		5.2. Information and Data Models
	An implementation supporting this document SHOULD allow the inclusion		An implementation supporting this document SHOULD allow the inclusion
	of color in the data model used to retrieve the operational state of		of color in the data model used to retrieve the operational state of
	a TE tunnel or an SR policy. The YANG model in [YANG-TE] could be		a TE Tunnel or an SR Policy. The YANG model in [YANG-TE] could be
	used to retrieve the operational state of a TE tunnel, and the YANG		used to retrieve the operational state of a TE Tunnel, and the YANG
	model in [SR-POLICY-YANG] could be used to retrieve the operational		model in [SR-POLICY-YANG] could be used to retrieve the operational
	state of an SR policy.		state of an SR Policy.
	5.3. Liveness Detection and Monitoring		5.3. Liveness Detection and Monitoring
	The extensions defined in this document do not require any additional		The extensions defined in this document do not require any additional
	liveness detection and monitoring support. See [RFC5440] and		liveness detection and monitoring support. See [RFC5440] and
	[RFC5886] for more information.		[RFC5886] for more information.
	5.4. Verifying Correct Operation		5.4. Verifying Correct Operation
	The operator MAY retrieve the operational state of TE Paths to verify		The operator MAY retrieve the operational state of TE Paths to verify
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