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Deterministic Networking (DetNet) Data Plane: IP over MPLS
RFC 9056

Document Type RFC - Proposed Standard (October 2021)
Authors Balazs Varga , Lou Berger , Don Fedyk , Stewart Bryant , Jouni Korhonen
Last updated 2021-10-04
RFC stream Internet Engineering Task Force (IETF)
Additional resources Mailing list discussion
IESG Responsible AD Deborah Brungard
Send notices to (None)
RFC 9056

Internet Engineering Task Force (IETF)                     B. Varga, Ed.
Request for Comments: 9056                                      Ericsson
Category: Standards Track                                      L. Berger
ISSN: 2070-1721                                                 D. Fedyk
                                                 LabN Consulting, L.L.C.
                                                               S. Bryant
                                                  Futurewei Technologies
                                                             J. Korhonen
                                                            October 2021

       Deterministic Networking (DetNet) Data Plane: IP over MPLS


   This document specifies the Deterministic Networking data plane when
   encapsulating IP over an MPLS packet-switched network.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at

Copyright Notice

   Copyright (c) 2021 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   ( in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction
   2.  Terminology
     2.1.  Terms Used in This Document
     2.2.  Abbreviations
     2.3.  Requirements Language
   3.  DetNet IP Data Plane Overview
   4.  DetNet IP over DetNet MPLS
     4.1.  DetNet IP over DetNet MPLS Data Plane Scenarios
     4.2.  DetNet IP over DetNet MPLS Encapsulation
   5.  DetNet IP over DetNet MPLS Procedures
     5.1.  DetNet IP over DetNet MPLS Flow Identification and
           Aggregation Procedures
     5.2.  DetNet IP over DetNet MPLS Traffic Treatment Procedures
   6.  Management and Control Information Summary
   7.  Security Considerations
   8.  IANA Considerations
   9.  References
     9.1.  Normative References
     9.2.  Informative References
   Authors' Addresses

1.  Introduction

   Deterministic Networking (DetNet) is a service that can be offered by
   a network to DetNet flows.  DetNet provides a capability for the
   delivery of data flows with extremely low packet loss rates and
   bounded end-to-end delivery latency.  General background and concepts
   of DetNet can be found in the DetNet architecture [RFC8655].

   This document specifies use of the IP DetNet encapsulation over an
   MPLS network.  It maps the IP data plane encapsulation described in
   [RFC8939] to the DetNet MPLS data plane defined in [RFC8964].

2.  Terminology

2.1.  Terms Used in This Document

   This document uses the terminology and concepts established in the
   DetNet architecture [RFC8655] and in [RFC8938].  The reader is
   assumed to be familiar with these documents and their terminology.

2.2.  Abbreviations

   This document uses the abbreviations defined in the DetNet
   architecture [RFC8655] and in [RFC8938].  This document uses the
   following abbreviations:

   CE            Customer Edge (equipment)

   d-CW          DetNet Control Word

   DetNet        Deterministic Networking

   DF            DetNet Flow

   DN            DetNet

   L2            Layer 2

   LSP           Label-Switched Path

   MPLS          Multiprotocol Label Switching

   PEF           Packet Elimination Function

   PRF           Packet Replication Function

   PREOF         Packet Replication, Elimination, and Ordering Functions

   POF           Packet Ordering Function

   PW            Pseudowire

   S-Label       DetNet "service" Label

   S-PE          Switching Provider Edge

   T-PE          Terminating Provider Edge

   TE            Traffic Engineering

   TSN           Time-Sensitive Networking; TSN is a Task Group of the
                 IEEE 802.1 Working Group

2.3.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "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.

3.  DetNet IP Data Plane Overview

   Figure 1 illustrates an IP DetNet with an MPLS-based DetNet network
   as a sub-network between the relay nodes.  An IP flow is mapped to
   one or more PWs and MPLS (TE) LSPs.  The end systems still originate
   IP-encapsulated traffic, identified as DetNet flows.  The relay nodes
   follow procedures defined in Section 4 to map each DetNet flow to
   MPLS LSPs.  While not shown, relay nodes can provide service sub-
   layer functions such as PREOF using DetNet over MPLS, and this is
   indicated by the solid line for the MPLS-facing portion of the
   Service component.  Note that the Transit node is MPLS (TE) LSP aware
   and performs switching based on MPLS labels; it need not have any
   specific knowledge of the DetNet service or the corresponding DetNet
   flow identification.  See Section 4 for details on the mapping of IP
   flows to MPLS, and [RFC8964] for general support of DetNet services
   using MPLS.

    DetNet IP       Relay         Transit         Relay      DetNet IP
    End System      Node           Node           Node       End System

   +----------+                                             +----------+
   |   Appl.  |<------------- End to End Service ---------->|  Appl.   |
   +----------+   .....-----+                 +-----.....   +----------+
   | Service  |<--: Service |--DetNet flow ---| Service :-->| Service  |
   |          |   :         |<-DN MPLS flow ->|         :   |          |
   +----------+   +---------+  +----------+   +---------+   +----------+
   |Forwarding|   |Fwd| |Fwd|  |Forwarding|   |Fwd| |Fwd|   |Forwarding|
   +-------.--+   +-.-+ +-.-+  +----.---.-+   +-.-+ +-.-+   +---.------+
           :  Link  :    /  ,-----.  \   : Link :    /  ,-----.  \
           +........+    +-[  Sub  ]-+   +......+    +-[  Sub  ]-+
                           [Network]                   [Network]
                            `-----'                     `-----'

                        |<---- DetNet MPLS ---->|
            |<--------------------- DetNet IP ------------------>|

         Figure 1: Architecture: DetNet IP over DetNet MPLS Network

4.  DetNet IP over DetNet MPLS

   This section defines how IP-encapsulated flows are carried over a
   DetNet MPLS data plane as defined in [RFC8964].  Since both non-
   DetNet and DetNet IP packets are identical on the wire, this section
   is applicable to any node that supports IP over DetNet MPLS, and this
   section refers to both cases as DetNet IP over DetNet MPLS.

4.1.  DetNet IP over DetNet MPLS Data Plane Scenarios

   An example use of DetNet IP over DetNet MPLS is presented here.

   Figure 1 illustrates IP DetNet-enabled End Systems (hosts) connected
   to DetNet-enabled IP networks (DN IP), operating over a DetNet-aware
   MPLS network.  In this figure, we have a case where the relay nodes
   act as T-PEs and sit at the boundary of the MPLS domain since the
   non-MPLS domain is DetNet aware.  This case is very similar to the
   DetNet MPLS Network (Figure 2 in [RFC8964]).  However, in Figure 2 of
   [RFC8964], the T-PEs are located at the end system and MPLS spans the
   whole DetNet service.  The primary difference in this document is
   that the relay nodes are at the edges of the MPLS domain and
   therefore function as T-PEs, and that MPLS service sub-layer
   functions are not provided over the DetNet IP network.  The transit
   node functions shown above are identical to those described in

   Figure 2 illustrates how relay nodes can provide service protection
   over an MPLS domain.  In this case, CE1 and CE2 are IP DetNet end
   systems that are interconnected via an MPLS domain such as that
   described in [RFC8964].  Note that R1 and R3 sit at the edges of an
   MPLS domain and therefore are similar to T-PEs, while R2 sits in the
   middle of the domain and is therefore similar to an S-PE.

         DetNet                                         DetNet
   IP    Service         Transit          Transit       Service  IP
   DetNet               |<-Tnl->|        |<-Tnl->|               DetNet
   End     |            V   1   V        V   2   V            |  End
   System  |   +--------+       +--------+       +--------+   |  System
   +---+   |   |   R1   |=======|   R2   |=======|   R3   |   |   +---+
   |   |-------|._X_....|..DF1..|.__ ___.|..DF3..|...._X_.|-------|   |
   |CE1|   |   |    \   |       |   X    |       |   /    |   |   |CE2|
   |   |   |   |     \_.|..DF2..|._/ \__.|..DF4..|._/     |   |   |   |
   +---+       |        |=======|        |=======|        |       +---+
       ^       +--------+       +--------+       +--------+       ^
       |        Relay Node       Relay Node       Relay Node      |
       |          (T-PE)           (S-PE)          (T-PE)         |
       |                                                          |
       |<-DN IP-> <-------- DetNet MPLS ---------------> <-DN IP->|
       |                                                          |
       |<-------------- End to End DetNet Service --------------->|

      -------------------------- Data Flow ------------------------->

       X   = Service protection (PRF, PREOF, PEF/POF)
       DFx = DetNet member flow x over a TE LSP

    Figure 2: Service Protection over DetNet MPLS Network for DetNet IP

   Figure 1 illustrates DetNet-enabled end systems connected to DetNet-
   enabled (DN) MPLS networks.  A similar situation occurs when end
   systems are not DetNet aware.  In this case, edge nodes sit at the
   boundary of the MPLS domain since it is also a DetNet domain
   boundary.  The edge nodes provide DetNet service proxies for the end
   applications by initiating and terminating DetNet service for the
   application's IP flows.  While the node types differ, there is
   essentially no difference in data plane processing between relays and
   edges.  There are likely to be differences in Controller Plane
   operation, particularly when distributed control plane protocols are

   It is still possible to provide DetNet service protection for non-
   DetNet-aware end systems.  This case is basically the same as
   Figure 2, with the exception that CE1 and CE2 are non-DetNet-aware
   end systems and R1 and R3 become edge nodes.

4.2.  DetNet IP over DetNet MPLS Encapsulation

   The basic encapsulation approach is to treat a DetNet IP flow as an
   App-flow from the DetNet MPLS perspective.  The corresponding example
   DetNet Sub-network format is shown in Figure 3.

                /->     +------+  +------+  +------+            ^ ^
                |       |  X   |  |  X   |  |  X   |<- App-flow : :
                |       +------+  +------+  +------+            : :
     App-flow <-+       |NProto|  |NProto|  |NProto|            : :(1)
      for MPLS  |       +------+  +------+  +------+            : :
                |       |  IP  |  |  IP  |  |  IP  |            : v
                \-> +---+======+--+======+--+======+-----+      :
     DetNet-MPLS        | d-CW |  | d-CW |  | d-CW |            :
                        +------+  +------+  +------+            :(2)
                        |Labels|  |Labels|  |Labels|            v
     Link/Sub-network   |  L2  |  | TSN  |  | UDP  |
                        +------+  +------+  +------+
                                            |  IP  |
                                            |  L2  |
         (1) DetNet IP Flow (or simply IP flow)
         (2) DetNet MPLS Flow

         Figure 3: Example DetNet IP over MPLS Sub-network Formats

   In Figure 3, "App-flow" indicates the payload carried by the DetNet
   IP data plane.  "IP" and "NProto" indicate the fields described in
   Sections 5.1.1 (IP Header Information) and 5.1.2 (Other Protocol
   Header Information) of [RFC8939], respectively.  "App-flow for MPLS"
   indicates that an individual DetNet IP flow is the payload from the
   perspective of the DetNet MPLS data plane defined in [RFC8964].

   Per Section 5.1 of [RFC8964], the DetNet MPLS data plane uses a
   single S-Label to support a single App-flow.  DetNet IP Flow
   Identification Procedures in Section 5.1 of [RFC8939] states that a
   single DetNet flow is identified based on IP- and next-level protocol
   header information.  Section 4.4 of [RFC8939] (DetNet Flow
   Aggregation) defines the ways in which aggregation is supported
   through the use of prefixes, wildcards, lists, and port ranges.
   Collectively, this results in the fairly straightforward procedures
   defined in the next section.

   As shown in Figure 2, DetNet relay nodes are responsible for the
   mapping of a DetNet flow, at the service sub-layer, from the IP to
   MPLS DetNet data planes and back again.  Their related DetNet IP over
   DetNet MPLS data plane operation is comprised of two sets of
   procedures: the mapping of flow identifiers and ensuring proper
   traffic treatment.

   Mapping of IP to DetNet MPLS is similar for DetNet IP flows and IP
   flows.  The six-tuple of IP is mapped to the S-Label in both cases.
   The various fields may be mapped or ignored when going from IP to

5.  DetNet IP over DetNet MPLS Procedures

   The main differences of mapping IP to DetNet MPLS (compared to plain
   MPLS) are that (1) there is a mandatory flow identification to make
   the forwarding decision (i.e., forwarding is not based on FEC), (2)
   the d-CW (DetNet Control Word) is mandatory for the MPLS
   encapsulation, and (3) during forwarding over the DetNet MPLS
   network, treatment specific to DetNet flows is needed.

5.1.  DetNet IP over DetNet MPLS Flow Identification and Aggregation

   A DetNet relay node (ingress T-PE) that sends a DetNet IP flow over a
   DetNet MPLS network MUST map a DetNet IP flow, as identified in
   [RFC8939], into a single MPLS DetNet flow and MUST process it in
   accordance to the procedures defined in [RFC8964].  PRF MAY be
   supported at the MPLS level for DetNet IP flows sent over a DetNet
   MPLS network.  Aggregation MAY be supported as defined in Section 4.4
   of [RFC8964].  Aggregation considerations in [RFC8939] MAY be used to
   identify an individual DetNet IP flow.  The provisioning of the
   mapping of DetNet IP flows to DetNet MPLS flows MUST be supported via
   configuration, e.g., via the Controller Plane.

   A DetNet relay node (egress T-PE) MAY be provisioned to handle
   packets received via the DetNet MPLS data plane as DetNet IP flows.
   A single incoming DetNet MPLS flow MAY be treated as a single DetNet
   IP flow, without examination of IP headers.  Alternatively, packets
   received via the DetNet MPLS data plane MAY follow the normal DetNet
   IP flow identification procedures defined in Section 5.1 of

   An implementation MUST support the provisioning for handling any
   packet flows received via the DetNet MPLS data plane as DetNet IP
   flows via configuration.  Note that such configuration MAY include
   support from PREOF on the incoming DetNet MPLS flow.

      |  Note: Using Layer 4 (L4) transport protocols (e.g., for
      |  multipath) are out of scope of this document both for a single
      |  flow and aggregate flows.

5.2.  DetNet IP over DetNet MPLS Traffic Treatment Procedures

   The traffic treatment required for a particular DetNet IP flow is
   provisioned via configuration or the Controller Plane.  When a DetNet
   IP flow is sent over DetNet MPLS, a DetNet relay node MUST ensure
   that the provisioned DetNet IP traffic treatment is provided at the
   forwarding sub-layer as described in Section 5.2 of [RFC8964].  Note
   that PRF MAY be utilized when sending IP over MPLS.

   Traffic treatment for DetNet IP flows received over the DetNet MPLS
   data plane MUST follow Section 5.3 of [RFC8939] (DetNet IP Traffic
   Treatment Procedures).

6.  Management and Control Information Summary

   The following summarizes the set of information that is needed to
   support DetNet IP over DetNet MPLS at the MPLS ingress node:

   *  Each MPLS App-Flow is selected from the incoming IP traffic using
      the IP flow identification information defined in [RFC8939].  This
      information is summarized in Section 5.1 of that document and
      includes all wildcards, port ranges, and the ability to ignore
      specific IP fields.

   *  The DetNet MPLS service that is to be used to send the matching IP
      traffic.  This matching information is provided in Section 5.1 of
      [RFC8964] and includes both service and traffic delivery

   The following summarizes the set of information that is needed to
   support DetNet IP over DetNet MPLS at the MPLS egress node:

   *  The S-Label value that identifies the encapsulated App-flow

   *  For each S-Label, how the received traffic is to be handled.  The
      traffic may be processed as any other DetNet IP traffic as defined
      in this document or in [RFC8939], or the traffic may be directly
      treated as an MPLS App-flow for additional processing according to

   It is the responsibility of the DetNet Controller Plane to properly
   provision both flow identification information and the flow-specific
   resources needed to provide the traffic treatment to meet each flow's
   service requirements.  This applies for aggregated and individual

7.  Security Considerations

   General security considerations for DetNet are described in detail in
   [RFC9055].  DetNet MPLS and DetNet IP security considerations equally
   apply to this document and are described in [RFC8964] and [RFC8939].

   Security aspects that are unique to DetNet are those whose aim is to
   protect the support of specific quality-of-service aspects of DetNet,
   which are primarily to deliver data flows with extremely low packet
   loss rates and bounded end-to-end delivery latency.

   The primary considerations for the data plane are to maintain
   integrity of data and delivery of the associated DetNet service
   traversing the DetNet network.  Application flows can be protected
   through whatever means is provided by the underlying technology.  For
   example, encryption may be used, such as that provided by IPsec
   [RFC4301] for IP flows and/or by an underlying sub-net using MACsec
   [IEEE802.1AE-2018] for IP-over-Ethernet (Layer 2) flows.

   From a data plane perspective, this document does not add or modify
   any header information.

   At the management and control level, DetNet flows are identified on a
   per-flow basis, which may provide Controller Plane attackers with
   additional information about the data flows (when compared to
   Controller Planes that do not include per-flow identification).  This
   is an inherent property of DetNet, which has security implications
   that should be considered when determining if DetNet is a suitable
   technology for any given use case.

   To provide uninterrupted availability of the DetNet service,
   provisions can be made against DoS attacks and delay attacks.  To
   protect against DoS attacks, excess traffic due to malicious or
   malfunctioning devices can be prevented or mitigated, for example,
   through the use of existing mechanisms such as policing and shaping
   applied at the input of a DetNet domain.  To prevent DetNet packets
   from being delayed by an entity external to a DetNet domain, DetNet
   technology definitions can allow for the mitigation of man-in-the-
   middle attacks (for example, through use of authentication and
   authorization of devices within the DetNet domain).

8.  IANA Considerations

   This document has no IANA actions.

9.  References

9.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <>.

   [RFC8655]  Finn, N., Thubert, P., Varga, B., and J. Farkas,
              "Deterministic Networking Architecture", RFC 8655,
              DOI 10.17487/RFC8655, October 2019,

   [RFC8938]  Varga, B., Ed., Farkas, J., Berger, L., Malis, A., and S.
              Bryant, "Deterministic Networking (DetNet) Data Plane
              Framework", RFC 8938, DOI 10.17487/RFC8938, November 2020,

   [RFC8939]  Varga, B., Ed., Farkas, J., Berger, L., Fedyk, D., and S.
              Bryant, "Deterministic Networking (DetNet) Data Plane:
              IP", RFC 8939, DOI 10.17487/RFC8939, November 2020,

   [RFC8964]  Varga, B., Ed., Farkas, J., Berger, L., Malis, A., Bryant,
              S., and J. Korhonen, "Deterministic Networking (DetNet)
              Data Plane: MPLS", RFC 8964, DOI 10.17487/RFC8964, January
              2021, <>.

   [RFC9055]  Grossman, E., Ed., Mizrahi, T., and A. Hacker,
              "Deterministic Networking (DetNet) Security
              Considerations", RFC 9055, DOI 10.17487/RFC9055, June
              2021, <>.

9.2.  Informative References

              IEEE, "IEEE Standard for Local and metropolitan area
              networks-Media Access Control (MAC) Security", IEEE
              802.1AE-2018, DOI 10.1109/IEEESTD.2018.8585421, December
              2018, <>.

   [RFC4301]  Kent, S. and K. Seo, "Security Architecture for the
              Internet Protocol", RFC 4301, DOI 10.17487/RFC4301,
              December 2005, <>.


   The authors wish to thank Pat Thaler, Norman Finn, Loa Andersson,
   David Black, Rodney Cummings, Ethan Grossman, Tal Mizrahi, David
   Mozes, Craig Gunther, George Swallow, Yuanlong Jiang, and Carlos
   J. Bernardos for their various contributions to this work.


   RFC 7322 limits the number of authors listed on the front page to a
   maximum of 5.  The editor wishes to thank and acknowledge the
   following authors for contributing text to this document.

   János Farkas


   Andrew G. Malis
   Malis Consulting


   János Farkas contributed substantially to the content of this

Authors' Addresses

   Balázs Varga (editor)
   Magyar Tudosok krt. 11.


   Lou Berger
   LabN Consulting, L.L.C.


   Don Fedyk
   LabN Consulting, L.L.C.


   Stewart Bryant
   Futurewei Technologies


   Jouni Korhonen