MPLS Network Actions for Network Resource Partition Selector
draft-ietf-mpls-mna-nrp-selector-06

MPLS Working Group                                                 T. Li
Internet-Draft                                              V. P. Beeram
Intended status: Standards Track                                     HPE
Expires: 6 November 2026                                        J. Drake
                                                                        
                                                                 T. Saad
                                                           Cisco Systems
                                                               I. Meilik
                                                                Broadcom
                                                              5 May 2026

      MPLS Network Actions for Network Resource Partition Selector
                  draft-ietf-mpls-mna-nrp-selector-06

Abstract

   An IETF Network Slice service provides connectivity coupled with a
   set of network resource commitments and is expressed in terms of one
   or more connectivity constructs.  A Network Resource Partition (NRP)
   is a collection of resources identified in the underlay network to
   support IETF Network Slice services.  A Slice-Flow Aggregate refers
   to the set of traffic streams from one or more connectivity
   constructs belonging to one or more IETF Network Slices that are
   mapped to a specific NRP and provide the same forwarding treatment.
   The packets associated with a Slice-Flow Aggregate may carry markings
   in the packet's network layer header to identify this association and
   each is referred to as NRP Selector.  The NRP Selector is used to map
   the packet to the associated NRP and provides the corresponding
   forwarding treatment to the packet.

   MPLS Network Actions (MNA) technologies are used to indicate actions
   for Label Switched Paths (LSPs) and/or MPLS packets and to transfer
   data needed for these actions.  This document specifies options for
   using MPLS Network Actions (MNAs) to carry the NRP Selector in MPLS
   packets.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

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   Internet-Drafts are draft documents valid for a maximum of six months
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Copyright Notice

   Copyright (c) 2026 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   4
   2.  MPLS Network Actions  . . . . . . . . . . . . . . . . . . . .   4
     2.1.  13-bit NRP Selector (NRPS13) Action . . . . . . . . . . .   4
     2.2.  20-bit NRP Selector (NRPS20) Action . . . . . . . . . . .   5
     2.3.  20-bit Entropy and NRP Selector (ENRPS20) Action  . . . .   6
     2.4.  Top-most NRPS Action  . . . . . . . . . . . . . . . . . .   8
     2.5.  Unknown NRPS  . . . . . . . . . . . . . . . . . . . . . .   8
   3.  Operational Considerations  . . . . . . . . . . . . . . . . .   8
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
     4.1.  13-bit NRP Selector Action  . . . . . . . . . . . . . . .   8
     4.2.  20-bit NRP Selector Action  . . . . . . . . . . . . . . .   8
     4.3.  20-bit Entropy and NRP Selector Action  . . . . . . . . .   9
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   6.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   9
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   9
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  11

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1.  Introduction

   An IETF Network Slice [RFC9543] service provides connectivity coupled
   with a set of specific commitments of network resources between a
   number of endpoints over a shared underlay network.  The IETF Network
   Slice service is expressed in terms of one or more connectivity
   constructs.  A Network Resource Partition (NRP) ([RFC9543],
   Section 7) is a collection of resources identified in the underlay
   network to support IETF Network Slice services (or any other services
   that need logical network structures with required characteristics to
   be created).  An NRP Policy is a policy construct that enables
   instantiation of mechanisms in support of service specific control
   and data plane behaviors on select topological elements associated
   with the NRP.  This is also discussed in [I-D.ietf-teas-ns-ip-mpls].

   A Slice-Flow Aggregate refers to the set of traffic streams from one
   or more connectivity constructs belonging to one or more IETF Network
   Slices that are mapped to a specific NRP and are provided the same
   forwarding treatment.  The NRP policy dictates the identification of
   the flow aggregate that the packet belongs to and the corresponding
   forwarding treatment that needs to be applied to the packet.  The
   packets associated with a Slice-Flow Aggregate may carry markings in
   the packet's network layer header to identify this association and
   each is referred to as NRP Selector (NRPS).
   [I-D.ietf-teas-ns-ip-mpls] discusses a few options for carrying the
   NRP Selector in MPLS packets, including overloading the semantics of
   forwarding/service labels and using a dedicated identifier field.

   [RFC9789] specifies an architectural framework for the MPLS Network
   Actions (MNA) technologies.  MNA technologies are used to indicate
   actions for Label Switched Paths (LSPs) and/or MPLS packets and to
   transfer data needed for these actions.  The MNA architecture can
   facilitate carrying the dedicated identifier based NRP Selector in
   the MPLS label stack.  This document discusses a few options for
   using MPLS network actions to carry the NRP Selector.  These
   encodings are compliant with the MNA header encoding formats defined
   in [I-D.ietf-mpls-mna-hdr].

   The reader is expected to be familiar with the terminology specified
   in [RFC9789] and MNA header encoding formats defined in
   [I-D.ietf-mpls-mna-hdr].

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1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.  These words may also appear in this
   document in lower case as plain English words, absent their normative
   meanings.

2.  MPLS Network Actions

   The MNA Label Stack Entries (LSEs) in the following subsections use
   the format and fields defined in [I-D.ietf-mpls-mna-hdr], Section 4,
   with no change to their meanings.  Only the Ancillary Data is
   modified to carry the NRPS Selector as described in each of the
   subsections.

2.1.  13-bit NRP Selector (NRPS13) Action

   The format of the 13-bit NRP Selector (NRPS13) Action (when encoded
   in the second label stack entry in the Network Action Sub-Stack) is:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Opcode=TBA1 |           NRPS          |R|IHS|S|  NASL |U| NAL |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

             Figure 1: A 13-bit NRP Selector in a Format B LSE

   This complies with MNA LSE Format B ([I-D.ietf-mpls-mna-hdr],
   Section 4.2).  The fields are:

   *  Opcode: The MNA Opcode (TBA1).  See [I-D.ietf-mpls-mna-hdr],
      Section 5.1.

   *  NRPS: Network Resource Partition Selector.  If this is the top-
      most NRPS in the label stack, the packet carrying the NRPS13
      action is to be given the forwarding treatment specified by the
      associated NRP policy.  See [I-D.ietf-teas-ns-ip-mpls],
      Section 5.1.1.

   *  R: Reserved.  See [I-D.ietf-mpls-mna-hdr], Section 4.2.

   *  IHS: The Scope of the NAS.  See [I-D.ietf-mpls-mna-hdr],
      Section 5.3.

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   *  S: The Bottom of Stack.  [RFC3032]

   *  NASL: The Network Action Sub-Stack Length (NASL).  See
      [I-D.ietf-mpls-mna-hdr], Section 4.2.

   *  U: Unknown Network Action Handling.  See [I-D.ietf-mpls-mna-hdr],
      Section 5.4.

   *  NAL: Network Action Length.  See [I-D.ietf-mpls-mna-hdr],
      Section 4.2.

   Each Network Action is required to specify the following by
   [I-D.ietf-mpls-mna-hdr]:

   *  Format: LSE Format B

   *  Scope: The NRPS13 Action is valid in all scopes.

   *  Ancillary Data: The NRPS13 Action carries 13 bits of ancillary
      data.  The NRPS is encoded in 13 bits.

   *  Processing: If this is the top-most NRPS in the label stack, the
      packet carrying the NRPS13 action is to be given the forwarding
      treatment specified by the associated NRP policy.

   *  Interactions: None

2.2.  20-bit NRP Selector (NRPS20) Action

   The format of the 20-bit NRP Selector (NRPS20) Action is:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Opcode=TBA2 |             NRPS              |S|  NRPS |U| NAL |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

             Figure 2: A 20-bit NRP Selector in a Format C LSE

   This complies with MNA LSE Format C ([I-D.ietf-mpls-mna-hdr],
   Section 4.3).  The fields are:

   *  Opcode: The MNA Opcode (TBA2).  See [I-D.ietf-mpls-mna-hdr],
      Section 5.1.

   *  NRPS: Network Resource Partition Selector.  This field is
      intentionally split across the S bit.  If this is the top-most
      NRPS in the label stack, the packet carrying the NRPS20 action is

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      to be given the forwarding treatment specified by the associated
      NRP policy.  See [I-D.ietf-mpls-mna-hdr], Section 4.3 and
      [I-D.ietf-teas-ns-ip-mpls], Section 5.1.1.

   *  S: The Bottom of Stack.  [RFC3032]

   *  U: Unknown Network Action Handling.  See [I-D.ietf-mpls-mna-hdr],
      Section 5.4.

   *  NAL: Network Action Length.  See [I-D.ietf-mpls-mna-hdr],
      Section 4.3.

   Each Network Action is required to specify the following by
   [I-D.ietf-mpls-mna-hdr]:

   *  Format: LSE Format C

   *  Scope: The NRPS20 Action is valid in all scopes.

   *  Ancillary Data: The NRPS20 Action carries 20 bits of ancillary
      data.  The NRPS is encoded in the 20 bits.

   *  Processing: If this is the top-most NRPS in the label stack, the
      packet carrying the NRPS20 action is to be given the forwarding
      treatment specified by the associated NRP policy.

   *  Interactions: None

2.3.  20-bit Entropy and NRP Selector (ENRPS20) Action

   The format of the 20-bit Entropy and NRP Selector (ENRPS20) Action
   is:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Opcode=TBA3 |        Entropy        | NRPS  |S|  NRPS |U| NAL |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Figure 3: A 12-bit Entropy Value and an 8-bit NRP Selector in a
                                Format C LSE

   This complies with MNA LSE Format C ([I-D.ietf-mpls-mna-hdr],
   Section 4.3).  The fields are:

   *  Opcode: The MNA Opcode (TBA3).  See [I-D.ietf-mpls-mna-hdr],
      Section 5.1.

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   *  Entropy: A 12-bit Entropy Value.  The Entropy Value has semantics
      consistent with the Entropy Label [RFC6790].  While the RFC 6790
      Entropy Label has some restrictions to avoid collisions with the
      reserved label space (0-15) [RFC3032], those restrictions are not
      necessary for the Entropy Value and do not apply.  The selection
      of the Opcode ensures that this cannot be mistaken for a reserved
      label.

   *  NRPS: Network Resource Partition Selector.  This field is
      intentionally split across the S bit.  If this is the top-most
      NRPS in the label stack, the packet carrying the ENRPS20 action is
      to be given the forwarding treatment specified by the associated
      NRP policy.  See [I-D.ietf-mpls-mna-hdr], Section 4.3 and
      [I-D.ietf-teas-ns-ip-mpls], Section 5.1.1.

   *  S: The Bottom of Stack.  [RFC3032]

   *  U: Unknown Network Action Handling.  See [I-D.ietf-mpls-mna-hdr],
      Section 5.4.

   *  NAL: Network Action Length.  See [I-D.ietf-mpls-mna-hdr],
      Section 4.3.

   Each Network Action is required to specify the following by
   [I-D.ietf-mpls-mna-hdr]:

   *  Format: LSE Format C

   *  Scope: The ENRPS20 Action is valid in all scopes.

   *  Ancillary Data: The ENRPS20 Action carries 20 bits of ancillary
      data.  The most significant 12 bits of ancillary data is the
      Entropy Value.  The least significant 8 bits of ancillary data is
      the NRPS.

   *  Processing: The Entropy Value has semantics consistent with the
      Entropy Label [RFC6790].  While the RFC 6790 Entropy Label has
      some restrictions to avoid collisions with the reserved label
      space (0-15) [RFC3032], those restrictions are not necessary for
      the Entropy Value and do not apply.  The selection of the Opcode
      ensures that this cannot be mistaken for a reserved label.  If
      this is the top-most NRPS in the label stack, the packet carrying
      the ENRPS20 action is to be given the forwarding treatment
      specified by the associated NRP policy.

   *  Interactions: None

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2.4.  Top-most NRPS Action

   Multiple NRPS Actions MAY be encoded in a single packet.  An
   implementation MUST use only the top-most NRPS Action to determine
   the packet's forwarding treatment.  An implementation that finds a
   subsequent opcode of any of the three NRPS Actions in the label stack
   MUST ignore it.  The specific scenarios where multiple NRPS Actions
   are present in the label stack are outside the scope of this
   document.  See [I-D.ietf-teas-ns-ip-mpls].

2.5.  Unknown NRPS

   An NRP-capable node SHOULD drop a packet by default if the encoded
   NRPS cannot be mapped to a known NRP.  This requirement MAY be
   overridden by an operator-specified policy, the specification of
   which is outside the scope of this document.  See
   [I-D.ietf-teas-ns-ip-mpls] for more details.

3.  Operational Considerations

   MNA In-stack operational considerations are discussed in
   [I-D.ietf-mpls-mna-hdr], Section 13.

   The choice of the number of bits to encode an NRP Selector is a
   network-wide deployment decision.  This decision may be constrained
   by implementations.

   The choice of which Action to use when the NRP Selector could fit in
   multiple Actions is open, but it is RECOMMENDED to use NRPS13 where
   possible unless Entropy is also to be carried and it is possible to
   use ENRPS20.

4.  IANA Considerations

4.1.  13-bit NRP Selector Action

   This document requests that IANA allocate a codepoint (TBA1) from the
   "Network Action Opcodes" registry in the "MPLS Network Actions" group
   [NAO] for the 13-bit NRP Selector Action.  The allocation should
   reference this document with the description " 13-bit NRP Selector".

4.2.  20-bit NRP Selector Action

   This document requests that IANA allocate a codepoint (TBA2) from the
   "Network Action Opcodes" registry in the "MPLS Network Actions" group
   [NAO] for the 20-bit NRP Selector Action.  The allocation should
   reference this document with the description "20-bit NRP Selector".

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4.3.  20-bit Entropy and NRP Selector Action

   This document requests that IANA allocate a codepoint (TBA3) from the
   "Network Action Opcodes" registry in the "MPLS Network Actions" group
   [NAO] for the 20-bit Entropy and NRP Selector Action.  The allocation
   should reference this document with the description "20-bit Entropy
   and NRP Selector".

5.  Security Considerations

   The forwarding plane is insecure.  If an adversary can affect the
   forwarding plane, then they can inject data, remove data, corrupt
   data, or modify data.  MNA additionally allows an adversary to make
   packets perform arbitrary network actions.

   Link-level security mechanisms can help mitigate some on-link
   attacks, but does nothing to preclude hostile nodes.

   Unauthorized use of an NRPS can lead to traffic receiving unintended
   resource treatment and/or disclosure of network policies.

   Further security considerations can be found in
   [I-D.ietf-teas-ns-ip-mpls], [I-D.ietf-mpls-mna-hdr], Section 12 and
   [RFC9789], Section 7.

6.  Contributors

   The following individuals contributed to this document:

   Colby Barth
   Juniper Networks
   Email: cbarth@juniper.net

   Srihari R.  Sangli
   Juniper Networks
   Email: ssangli@juniper.net

   Chandra Ramachandran
   Juniper Networks
   Email: csekar@juniper.net

   Kireeti Kompella
   Juniper Networks
   Email: kireeti@juniper.net

7.  References

7.1.  Normative References

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   [I-D.ietf-mpls-mna-hdr]
              Rajamanickam, J., Gandhi, R., Zigler, R., Song, H., and K.
              Kompella, "MPLS Network Action (MNA) Sub-Stack
              Specification including In-Stack Network Actions and
              Data", Work in Progress, Internet-Draft, draft-ietf-mpls-
              mna-hdr-21, 24 February 2026,
              <https://datatracker.ietf.org/doc/html/draft-ietf-mpls-
              mna-hdr-21>.

   [I-D.ietf-teas-ns-ip-mpls]
              Saad, T., Beeram, V. P., Dong, J., Halpern, J. M., and S.
              Peng, "Realizing Network Slices in IP/MPLS Networks", Work
              in Progress, Internet-Draft, draft-ietf-teas-ns-ip-mpls-
              07, 28 February 2026,
              <https://datatracker.ietf.org/doc/html/draft-ietf-teas-ns-
              ip-mpls-07>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC3032]  Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y.,
              Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack
              Encoding", RFC 3032, DOI 10.17487/RFC3032, January 2001,
              <https://www.rfc-editor.org/info/rfc3032>.

   [RFC6790]  Kompella, K., Drake, J., Amante, S., Henderickx, W., and
              L. Yong, "The Use of Entropy Labels in MPLS Forwarding",
              RFC 6790, DOI 10.17487/RFC6790, November 2012,
              <https://www.rfc-editor.org/info/rfc6790>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC9543]  Farrel, A., Ed., Drake, J., Ed., Rokui, R., Homma, S.,
              Makhijani, K., Contreras, L., and J. Tantsura, "A
              Framework for Network Slices in Networks Built from IETF
              Technologies", RFC 9543, DOI 10.17487/RFC9543, March 2024,
              <https://www.rfc-editor.org/info/rfc9543>.

   [RFC9789]  Andersson, L., Bryant, S., Bocci, M., and T. Li, "MPLS
              Network Actions (MNAs) Framework", RFC 9789,
              DOI 10.17487/RFC9789, July 2025,
              <https://www.rfc-editor.org/info/rfc9789>.

7.2.  Informative References

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   [NAO]      "MPLS Network Actions, Network Action Opcodes", May 2026,
              <https://www.iana.org/assignments/mpls-network-actions/
              mpls-network-actions.xhtml#network-action-opcodes>.

Authors' Addresses

   Tony Li
   HPE
   1701 E Mossy Oaks Rd.
   Spring, TX 77389
   United States
   Email: tony.li@tony.li

   Vishnu Pavan Beeram
   HPE
   1701 E Mossy Oaks Rd.
   Spring, TX 77389
   United States
   Email: vbeeram@juniper.net

   John Drake
   Email: je_drake@yahoo.com

   Tarek Saad
   Cisco Systems
   Email: tsaad.net@gmail.com

   Israel Meilik
   Broadcom
   Email: israel.meilik@broadcom.com

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