rfc9789v2.txt		rfc9789.txt
	skipping to change at line 12 ¶		skipping to change at line 12 ¶
	Internet Engineering Task Force (IETF) L. Andersson		Internet Engineering Task Force (IETF) L. Andersson
	Request for Comments: 9789 Huawei Technologies		Request for Comments: 9789 Huawei Technologies
	Category: Informational S. Bryant		Category: Informational S. Bryant
	ISSN: 2070-1721 University of Surrey 5GIC		ISSN: 2070-1721 University of Surrey 5GIC
	M. Bocci		M. Bocci
	Nokia		Nokia
	T. Li		T. Li
	Juniper Networks		Juniper Networks
	May 2025		May 2025
	MPLS Network Action (MNA) Framework		MPLS Network Actions (MNAs) Framework
	Abstract		Abstract
	This document describes an architectural framework for MPLS Network		This document describes an architectural framework for MPLS Network
	Action (MNA) technologies. MNA technologies are used to indicate		Action (MNA) technologies. MNA technologies are used to indicate
	actions that impact the forwarding or other processing (such as		actions that impact the forwarding or other processing (such as
	monitoring) of the packet along the Label Switched Path (LSP) of the		monitoring) of the packet along the Label Switched Path (LSP) of the
	packet and to transfer any additional data needed for these actions.		packet and to transfer any additional data needed for these actions.
	This document provides the foundation for the development of a common		This document provides the foundation for the development of a common
	skipping to change at line 159 ¶		skipping to change at line 159 ¶
	abbreviations from [RFC9613] as normative: "Network Action", "Network		abbreviations from [RFC9613] as normative: "Network Action", "Network
	Action Indicator (NAI)", "Ancillary Data (AD)", and "Scope".		Action Indicator (NAI)", "Ancillary Data (AD)", and "Scope".
	In addition, this document defines the following terms:		In addition, this document defines the following terms:
	Network Action Sub-Stack (NAS): A set of related, contiguous LSEs in		Network Action Sub-Stack (NAS): A set of related, contiguous LSEs in
	the MPLS label stack for carrying information related to network		the MPLS label stack for carrying information related to network
	actions. The Label, TC, and TTL values in the LSEs in the NAS may		actions. The Label, TC, and TTL values in the LSEs in the NAS may
	be redefined, but the meaning of the S bit is unchanged.		be redefined, but the meaning of the S bit is unchanged.
	Network Action Sub-Stack Indicator (NSI): The first LSE in the NAS		Network Action Sub-Stack Indicator (NSI): The first LSE in the NAS,
	contains a special-purpose label that indicates the start of the		which contains a special-purpose label that indicates the start of
	NAS.		the NAS.
	1.3. Abbreviations		1.3. Abbreviations
	+==============+=====================+=====================+		+==============+=====================+=====================+
	| Abbreviation | Meaning | Reference |		| Abbreviation | Meaning | Reference |
	+==============+=====================+=====================+		+==============+=====================+=====================+
	| AD | Ancillary Data | [RFC9613] |		| AD | Ancillary Data | [RFC9613] |
	+--------------+---------------------+---------------------+		+--------------+---------------------+---------------------+
	| BIER | Bit Index Explicit | [RFC8279] |		| BIER | Bit Index Explicit | [RFC8279] |
	| | Replication | |		| | Replication | |
	skipping to change at line 256 ¶		skipping to change at line 256 ¶
	many points along an LSP. Replication of ancillary data throughout		many points along an LSP. Replication of ancillary data throughout
	the label stack would be highly inefficient, as would a full rewrite		the label stack would be highly inefficient, as would a full rewrite
	of the label stack at each hop; thus, MNA allows encoding of network		of the label stack at each hop; thus, MNA allows encoding of network
	actions and ancillary data deeper in the label stack, requiring		actions and ancillary data deeper in the label stack, requiring
	implementations to look past the first LSE. Processing of the label		implementations to look past the first LSE. Processing of the label
	stack past the top-of-stack LSE was first introduced with the Entropy		stack past the top-of-stack LSE was first introduced with the Entropy
	Label (EL) [RFC6790].		Label (EL) [RFC6790].
	A network action sub-stack contains:		A network action sub-stack contains:
	* Network Action Sub-Stack Indicator (NSI): The first LSE in the NAS		* Network Action Sub-Stack Indicator (NSI): The first LSE in the
	contains a special-purpose label, called the MNA label, which is		NAS, which contains a special-purpose label, called the MNA label,
	used to indicate the start of a network action sub-stack.		that is used to indicate the start of a network action sub-stack.
	* Network Action Indicators (NAIs): Optionally, a set of indicators		* Network Action Indicators (NAIs): Optionally, a set of indicators
	that describes the set of network actions. If the set of		that describes the set of network actions. If the set of
	indicators is not in the sub-stack, a solution could encode them		indicators is not in the sub-stack, a solution could encode them
	in post-stack data. A network action is said to be present if		in post-stack data. A network action is said to be present if
	there is an indicator in the packet that invokes the action.		there is an indicator in the packet that invokes the action.
	* In-Stack Data (ISD): A set of zero or more LSEs that carry		* In-Stack Data (ISD): A set of zero or more LSEs that carry
	ancillary data for the network actions that are present. Network		ancillary data for the network actions that are present. Network
	action indicators are not considered ancillary data.		action indicators are not considered ancillary data.
	skipping to change at line 703 ¶		skipping to change at line 703 ¶
	Nevertheless, the method is implemented and deployed; it is used		Nevertheless, the method is implemented and deployed; it is used
	today and will be for the foreseeable future.		today and will be for the foreseeable future.
	The use of the first nibble for Bit Index Explicit Replication (BIER)		The use of the first nibble for Bit Index Explicit Replication (BIER)
	is specified in [RFC8296]. BIER sets the first nibble to 5. The		is specified in [RFC8296]. BIER sets the first nibble to 5. The
	same is true for a BIER payload as for any use of the first nibble:		same is true for a BIER payload as for any use of the first nibble:
	it is not possible to conclude that the payload is BIER even if the		it is not possible to conclude that the payload is BIER even if the
	first nibble is set to 5 because an Ethernet pseudowire without a		first nibble is set to 5 because an Ethernet pseudowire without a
	control word might begin with a 5. However, the BIER approach meets		control word might begin with a 5. However, the BIER approach meets
	the design goal of [RFC8296] to determine that the payload is IPv4,		the design goal of [RFC8296] to determine that the payload is IPv4,
	IPv6, or the header of a pseudowire packet with a control word,		IPv6, or a packet with a header that includes a pseudowire control
	rather than being a payload belonging to a BIER or some other type of		word.
	packet.
	[RFC4385] allocates 0b0000 for the pseudowire control word and 0b0001		[RFC4385] allocates 0b0000 for the pseudowire control word and 0b0001
	as the control word for the pseudowire Associated Channel Header		as the control word for the pseudowire Associated Channel Header
	(ACH).		(ACH).
	A PSD solution should specify the contents of the first nibble, the		A PSD solution should specify the contents of the first nibble, the
	actions to be taken for the value, and the interaction with post-		actions to be taken for the value, and the interaction with post-
	stack data used concurrently by other MPLS applications.		stack data used concurrently by other MPLS applications.
	4. Semantics		4. Semantics
End of changes. 4 change blocks.
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