Diff: rfc9791v1.txt - rfc9791.txt

	rfc9791v1.txt	rfc9791.txt

	Internet Engineering Task Force (IETF) T. Saad	Internet Engineering Task Force (IETF) T. Saad
	Request for Comments: 9791 Cisco Systems, Inc.	Request for Comments: 9791 Cisco Systems, Inc.
	Category: Informational K. Makhijani	Category: Informational K. Makhijani
	ISSN: 2070-1721 Independent	ISSN: 2070-1721 Independent
	H. Song	H. Song
	Futurewei Technologies	Futurewei Technologies
	G. Mirsky	G. Mirsky
	Ericsson	Ericsson

	May 2025	July 2025


	Use Cases for MPLS Network Action Indicators and MPLS Ancillary Data	Use Cases for MPLS Network Action Indicators and Ancillary Data

	Abstract	Abstract

	This document presents use cases that have a common feature that may	This document presents use cases that have a common feature that may
	be addressed by encoding network action indicators and associated	be addressed by encoding network action indicators and associated
	ancillary data within MPLS packets. There is community interest in	ancillary data within MPLS packets. There is community interest in
	extending the MPLS data plane to carry such indicators and ancillary	extending the MPLS data plane to carry such indicators and ancillary
	data to address these use cases.	data to address these use cases.

	The use cases described in this document are not an exhaustive set	The use cases described in this document are not an exhaustive set

	skipping to change at line 116 ¶	skipping to change at line 116 ¶

	1.1. Terminology	1.1. Terminology

	The following terminology is used in the document:	The following terminology is used in the document:

	RFC 9543 Network Slice:	RFC 9543 Network Slice:
	Interpreted as defined in [RFC9543]. This document uses "network	Interpreted as defined in [RFC9543]. This document uses "network
	slice" interchangeably as a shorter version of the term "RFC 9543	slice" interchangeably as a shorter version of the term "RFC 9543
	Network Slice".	Network Slice".


	MPLS Ancillary Data:	MPLS Ancillary Data (also referred to in this document as
		"ancillary data"):
	Data that can be classified as:	Data that can be classified as:

	* residing within the MPLS label stack (referred to as "in-stack	* residing within the MPLS label stack (referred to as "in-stack
	data"), and	data"), and

	* residing after the Bottom of Stack (BoS) (referred to as "post-	* residing after the Bottom of Stack (BoS) (referred to as "post-
	stack data").	stack data").

	1.2. Abbreviations	1.2. Abbreviations


	MNA: MPLS Network Action	AMM: Alternative Marking Method

	DEX: Direct Export


	I2E: Ingress to Edge	BoS: Bottom of Stack


	HbH: Hop by Hop	DEX: Direct Export


	PW: Pseudowire	eSPL: extended Special-Purpose Label


	BoS: Bottom of Stack	FRR: Fast Reroute


	ToS: Top of Stack	G-ACh: Generic Associated Channel


	NSH: Network Service Header	HbH: Hop by Hop


	FRR: Fast Reroute	I2E: Ingress to Egress

	IOAM: In situ Operations, Administration, and Maintenance	IOAM: In situ Operations, Administration, and Maintenance


	G-ACh: Generic Associated Channel

	LSP: Label Switched Path	LSP: Label Switched Path

	LSR: Label Switching Router	LSR: Label Switching Router


		MNA: MPLS Network Action

	NRP: Network Resource Partition	NRP: Network Resource Partition


	SPL: Special-Purpose Label	NSH: Network Service Header


	eSPL: extended Special-Purpose Label	PW: Pseudowire


	AMM: Alternative Marking Method	SPL: Special-Purpose Label

		ToS: Top of Stack

	2. Use Cases	2. Use Cases

	2.1. No Further Fast Reroute	2.1. No Further Fast Reroute

	MPLS Fast Reroute [RFC4090] [RFC5286] [RFC7490] [SR-TI-LFA] is a	MPLS Fast Reroute [RFC4090] [RFC5286] [RFC7490] [SR-TI-LFA] is a
	useful and widely deployed tool for minimizing packet loss in the	useful and widely deployed tool for minimizing packet loss in the
	case of a link or node failure.	case of a link or node failure.

	Several cases exist where, once a Fast Reroute (FRR) has taken place	Several cases exist where, once a Fast Reroute (FRR) has taken place

	skipping to change at line 196 ¶	skipping to change at line 197 ¶
	the operational state and telemetry information collected on the LSR	the operational state and telemetry information collected on the LSR
	may be transported using MNA techniques.	may be transported using MNA techniques.

	2.2.1. In Situ OAM	2.2.1. In Situ OAM

	In situ Operations, Administration, and Maintenance (IOAM), defined	In situ Operations, Administration, and Maintenance (IOAM), defined
	in [RFC9197] and [RFC9326], might be used to collect operational and	in [RFC9197] and [RFC9326], might be used to collect operational and
	telemetry information while a packet traverses a particular path in a	telemetry information while a packet traverses a particular path in a
	network domain.	network domain.


	IOAM can run in two modes: Ingress to Edge (I2E) and Hop by Hop	IOAM can run in two modes: Ingress to Egress (I2E) and Hop by Hop
	(HbH). In I2E mode, only the encapsulating and decapsulating nodes	(HbH). In I2E mode, only the encapsulating and decapsulating nodes
	will process IOAM data fields. In HbH mode, the encapsulating and	will process IOAM data fields. In HbH mode, the encapsulating and
	decapsulating nodes and intermediate IOAM-capable nodes process IOAM	decapsulating nodes and intermediate IOAM-capable nodes process IOAM
	data fields. The IOAM data fields, defined in [RFC9197], can be used	data fields. The IOAM data fields, defined in [RFC9197], can be used
	to derive the operational state of the network experienced by the	to derive the operational state of the network experienced by the
	packet with the IOAM Header that traversed the path through the IOAM	packet with the IOAM Header that traversed the path through the IOAM
	domain.	domain.

	Several IOAM Option-Types have been defined:	Several IOAM Option-Types have been defined:


	skipping to change at line 268 ¶	skipping to change at line 269 ¶
	treatments.	treatments.

	MNA technologies can signal actions for MPLS packets and carry data	MNA technologies can signal actions for MPLS packets and carry data
	essential for these actions. For example, MNA can carry the NRP	essential for these actions. For example, MNA can carry the NRP
	Selector [NS-IP-MPLS] in MPLS packets.	Selector [NS-IP-MPLS] in MPLS packets.

	2.4. NSH-Based Service Function Chaining	2.4. NSH-Based Service Function Chaining

	[RFC8595] describes how Service Function Chaining can be realized in	[RFC8595] describes how Service Function Chaining can be realized in
	an MPLS network by emulating the Network Service Header (NSH)	an MPLS network by emulating the Network Service Header (NSH)

	[RFC8300] using only MPLS label stack elements.	[RFC8300] using only MPLS label stack entries.

	The approach in [RFC8595] introduces some limitations, which are	The approach in [RFC8595] introduces some limitations, which are
	discussed in [SFP-VERIF]. However, the approach can benefit from the	discussed in [SFP-VERIF]. However, the approach can benefit from the
	MNA framework introduced in [RFC9789].	MNA framework introduced in [RFC9789].

	MNA can be used to extend NSH emulation using MPLS labels [RFC8595]	MNA can be used to extend NSH emulation using MPLS labels [RFC8595]
	to support the functionality of NSH Context Headers, whether fixed or	to support the functionality of NSH Context Headers, whether fixed or
	variable length. For example, MNA could support Flow ID [RFC9263]	variable length. For example, MNA could support Flow ID [RFC9263]
	that may be used for load-balancing among Service Function Forwarders	that may be used for load-balancing among Service Function Forwarders
	and/or the Service Functions within the same Service Function Path.	and/or the Service Functions within the same Service Function Path.

	skipping to change at line 321 ¶	skipping to change at line 322 ¶
	the presence of the PW CW.	the presence of the PW CW.

	In addition to providing connectivity to user traffic, MPLS may also	In addition to providing connectivity to user traffic, MPLS may also
	transport OAM data (e.g., over MPLS Generic Associated Channels	transport OAM data (e.g., over MPLS Generic Associated Channels
	(G-AChs) [RFC5586]). In this case, the first nibble of the data that	(G-AChs) [RFC5586]). In this case, the first nibble of the data that
	immediately follows the MPLS BoS is set to 0b0001. It indicates the	immediately follows the MPLS BoS is set to 0b0001. It indicates the
	presence of a control channel associated with a PW, LSP, or section.	presence of a control channel associated with a PW, LSP, or section.

	Bit Index Explicit Replication (BIER) [RFC8296] traffic can also be	Bit Index Explicit Replication (BIER) [RFC8296] traffic can also be
	encapsulated over MPLS. In this case, BIER has defined 0b0101 as the	encapsulated over MPLS. In this case, BIER has defined 0b0101 as the

	value for the first nibble of the data that immediately follows the	value for the first nibble of the data that immediately appears after
	bottom of the label stack for any BIER-encapsulated packet over MPLS.	the BoS for any BIER-encapsulated packet over MPLS.

	For PWs, the G-ACh [RFC7212] uses the first four bits of the PW	For PWs, the G-ACh [RFC7212] uses the first four bits of the PW
	control word to provide the initial discrimination between data	control word to provide the initial discrimination between data
	packets and packets belonging to the associated channel, as described	packets and packets belonging to the associated channel, as described
	in [RFC4385].	in [RFC4385].

	MPLS can be used as the data plane for Deterministic Networking	MPLS can be used as the data plane for Deterministic Networking
	(DetNet) [RFC8655]. The DetNet sub-layers, forwarding, and service	(DetNet) [RFC8655]. The DetNet sub-layers, forwarding, and service
	are realized using the MPLS label stack, the DetNet control word	are realized using the MPLS label stack, the DetNet control word
	[RFC8964], and the DetNet Associated Channel Header [RFC9546].	[RFC8964], and the DetNet Associated Channel Header [RFC9546].

	skipping to change at line 357 ¶	skipping to change at line 358 ¶
	Objectives (SLOs) are being met by the network provider. In this	Objectives (SLOs) are being met by the network provider. In this
	case, IOAM can collect key performance measurement parameters of a	case, IOAM can collect key performance measurement parameters of a
	network slice traffic flow as it traverses the transport network.	network slice traffic flow as it traverses the transport network.

	5. IANA Considerations	5. IANA Considerations

	This document has no IANA actions.	This document has no IANA actions.

	6. Security Considerations	6. Security Considerations


	Section 7 of the MNA framework [RFC9789] outlines security	Section 7 of [RFC9789] outlines security considerations for documents
	considerations for documents that do not specify protocols. The	that do not specify protocols. The authors have verified that these
	authors have verified that these considerations are fully applicable	considerations are fully applicable to this document.
	to this document.

	In-depth security analysis for each specific use case is beyond the	In-depth security analysis for each specific use case is beyond the
	scope of this document and will be addressed in future solution	scope of this document and will be addressed in future solution
	documents. It is strongly recommended that these solution documents	documents. It is strongly recommended that these solution documents
	undergo review by a security expert early in their development,	undergo review by a security expert early in their development,
	ideally during the Working Group Last Call phase.	ideally during the Working Group Last Call phase.

	7. References	7. References

	7.1. Normative References	7.1. Normative References

	[RFC9789] Andersson, L., Bryant, S., Bocci, M., and T. Li, "MPLS	[RFC9789] Andersson, L., Bryant, S., Bocci, M., and T. Li, "MPLS

	Network Action (MNA) Framework", RFC 9789,	Network Actions (MNAs) Framework", RFC 9789,
	DOI 10.17487/RFC9789, May 2025,	DOI 10.17487/RFC9789, July 2025,
	<https://www.rfc-editor.org/info/rfc9789>.	<https://www.rfc-editor.org/info/rfc9789>.

	7.2. Informative References	7.2. Informative References

	[GDF] Zhang, Z., Bonica, R., Kompella, K., and G. Mirsky,	[GDF] Zhang, Z., Bonica, R., Kompella, K., and G. Mirsky,
	"Generic Delivery Functions", Work in Progress, Internet-	"Generic Delivery Functions", Work in Progress, Internet-
	Draft, draft-zzhang-intarea-generic-delivery-functions-03,	Draft, draft-zzhang-intarea-generic-delivery-functions-03,
	11 July 2022, <https://datatracker.ietf.org/doc/html/	11 July 2022, <https://datatracker.ietf.org/doc/html/
	draft-zzhang-intarea-generic-delivery-functions-03>.	draft-zzhang-intarea-generic-delivery-functions-03>.


	skipping to change at line 518 ¶	skipping to change at line 518 ¶
	Networking (DetNet) with the MPLS Data Plane", RFC 9546,	Networking (DetNet) with the MPLS Data Plane", RFC 9546,
	DOI 10.17487/RFC9546, February 2024,	DOI 10.17487/RFC9546, February 2024,
	<https://www.rfc-editor.org/info/rfc9546>.	<https://www.rfc-editor.org/info/rfc9546>.

	[RFC9613] Bocci, M., Ed., Bryant, S., and J. Drake, "Requirements	[RFC9613] Bocci, M., Ed., Bryant, S., and J. Drake, "Requirements
	for Solutions that Support MPLS Network Actions (MNAs)",	for Solutions that Support MPLS Network Actions (MNAs)",
	RFC 9613, DOI 10.17487/RFC9613, August 2024,	RFC 9613, DOI 10.17487/RFC9613, August 2024,
	<https://www.rfc-editor.org/info/rfc9613>.	<https://www.rfc-editor.org/info/rfc9613>.

	[SFP-VERIF]	[SFP-VERIF]

	Yao, L. and G. Mirsky, "MPLS-based Service Function	Liu, Y. and G. Mirsky, "MPLS-based Service Function
	Path(SFP) Consistency Verification", Work in Progress,	Path(SFP) Consistency Verification", Work in Progress,
	Internet-Draft, draft-lm-mpls-sfc-path-verification-03, 11	Internet-Draft, draft-lm-mpls-sfc-path-verification-03, 11
	June 2022, <https://datatracker.ietf.org/doc/html/draft-	June 2022, <https://datatracker.ietf.org/doc/html/draft-
	lm-mpls-sfc-path-verification-03>.	lm-mpls-sfc-path-verification-03>.

	[SR-TI-LFA]	[SR-TI-LFA]
	Bashandy, A., Litkowski, S., Filsfils, C., Francois, P.,	Bashandy, A., Litkowski, S., Filsfils, C., Francois, P.,
	Decraene, B., and D. Voyer, "Topology Independent Fast	Decraene, B., and D. Voyer, "Topology Independent Fast
	Reroute using Segment Routing", Work in Progress,	Reroute using Segment Routing", Work in Progress,
	Internet-Draft, draft-ietf-rtgwg-segment-routing-ti-lfa-	Internet-Draft, draft-ietf-rtgwg-segment-routing-ti-lfa-

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