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<rfc category="info" xmlns:xi="http://www.w3.org/2001/XInclude" docName="draft-ietf-detnet-mpls-over-tsn-07"
number="9037" ipr="trust200902"
         submissionType="IETF"> submissionType="IETF" category="info" consensus="true"
obsoletes="" updates="" xml:lang="en" tocInclude="true" symRefs="true" sortRefs="true"
version="3">

  <!-- xml2rfc v2v3 conversion 3.5.0 -->
  <front>
    <title abbrev="DetNet MPLS over TSN">
    DetNet
    Deterministic Networking (DetNet) Data Plane: MPLS over IEEE 802.1 Time-Sensitive Networking (TSN)</title>
    <seriesInfo name="RFC" value="9037"/>
    <author role="editor" fullname="Bal&aacute;zs fullname="Balázs Varga" initials="B." surname="Varga">
      <organization>Ericsson</organization>
      <address>
        <postal>
          <street>Magyar Tudosok krt. 11.</street>
          <city>Budapest</city>
          <country>Hungary</country>
          <code>1117</code>
        </postal>
        <email>balazs.a.varga@ericsson.com</email>
      </address>
    </author>
    <author fullname="J&aacute;nos fullname="János Farkas" initials="J." surname="Farkas">
      <organization>Ericsson</organization>
      <address>
        <postal>
          <street>Magyar Tudosok krt. 11.</street>
          <city>Budapest</city>
          <country>Hungary</country>
          <code>1117</code>
        </postal>
        <email>janos.farkas@ericsson.com</email>
      </address>
    </author>
    <author fullname="Andrew G. Malis" initials="A.G." initials="A." surname="Malis">
      <organization>Malis Consulting</organization>
      <address>
        <email>agmalis@gmail.com</email>
      </address>
    </author>
    <author fullname="Stewart Bryant" initials="S." surname="Bryant">
      <organization>Futurewei Technologies</organization>
      <address>
        <email>stewart.bryant@gmail.com</email>
        <email>sb@stewartbryant.com</email>
      </address>
    </author>
    <date year="2021" month="June" />
    <workgroup>DetNet</workgroup>
    <abstract>
      <t>
     This document specifies the Deterministic Networking (DetNet) MPLS data plane
     when operating over an IEEE 802.1 Time-Sensitive Networking (TSN)
	 sub-network. This document does not define
	 new procedures or processes.  Whenever this document makes
	 statements or recommendations, these they are taken from normative text in the
	 referenced RFCs.
      </t>
    </abstract>
  </front>
  <middle>
    <section title="Introduction" anchor="sec_intro"> anchor="sec_intro" numbered="true" toc="default">
      <name>Introduction</name>
      <t>
    Deterministic Networking (DetNet) is a service that can be offered by a
    network to DetNet flows.  DetNet provides these flows with low packet loss
    rate and assured maximum end-to-end delivery latency.  General background
    and concepts of DetNet can be found in <xref
    target="RFC8655"/>. target="RFC8655" format="default"/>.
      </t>
      <t>
    The DetNet Architecture architecture decomposes the DetNet related DetNet-related data plane
    functions into two sub-layers: a service sub-layer and a forwarding sub-layer.
    The service sub-layer is used to provide DetNet service protection and
    reordering. The forwarding sub-layer is used to provide congestion
    protection (low loss, assured latency, and limited reordering)
    leveraging MPLS Traffic Engineering mechanisms.
      </t>
      <t>
	<xref target="RFC8964"/> target="RFC8964" format="default"/> specifies the DetNet data plane
	operation for an MPLS-based Packet Switched Network (PSN).  MPLS encapsulated PSN.  MPLS-encapsulated
	DetNet flows can be carried over network technologies that can provide the
	DetNet required
	DetNet-required level of service. This document focuses on the scenario
	where MPLS (DetNet) nodes are interconnected by a an IEEE 802.1 TSN sub-network.
	There is close cooperation between the IETF DetNet WG Working Group and the IEEE 802.1 TSN TG. Time-Sensitive Networking Task Group (TSN TG).
      </t>
    </section>
    <section title="Terminology"> numbered="true" toc="default">
      <name>Terminology</name>
      <section title="Terms numbered="true" toc="default">
        <name>Terms Used in This Document"> Document</name>
        <t>
   This document uses the terminology established in the DetNet architecture
   <xref target="RFC8655"/> and target="RFC8655" format="default"/>
   <xref target="RFC8964"/>.  TSN specific target="RFC8964" format="default"/>.  TSN-specific terms are defined in the TSN TG
		of the IEEE 802.1 Working Group.  The reader is assumed
   to be familiar with these documents and their terminology.
        </t>
      </section>
      <section title="Abbreviations"> numbered="true" toc="default">
        <name>Abbreviations</name>
        <t>
   The following abbreviations are used in this document:
   <list style="hanging" hangIndent="14">
    <t hangText="A-Label">Aggregation label,
        </t>
        <dl newline="false" spacing="normal" indent="14">
          <dt>A-Label</dt>
          <dd>Aggregation label; a special case of an S-Label.</t>
    <t hangText="d-CW">DetNet S-Label.</dd>
          <dt>d-CW</dt>
          <dd>DetNet Control Word.</t>
    <t hangText="DetNet">Deterministic Networking.</t>
	<t hangText="F-Label">Forwarding Word</dd>
          <dt>DetNet</dt>
          <dd>Deterministic Networking</dd>
          <dt>F-Label</dt>
          <dd>Forwarding label that identifies the LSP used by a
	DetNet flow.</t>
    <t hangText="FRER">Frame flow.</dd>
          <dt>FRER</dt>
          <dd>Frame Replication and Elimination for Redundancy
	(TSN function).</t>
    <t hangText="L2">Layer 2.</t>
    <t hangText="L3">Layer 3.</t>
    <t hangText="MPLS">Multiprotocol function)</dd>
          <dt>L2</dt>
          <dd>Layer 2</dd>
          <dt>L3</dt>
          <dd>Layer 3</dd>
          <dt>LSP</dt><dd>Label Switched Path</dd>
          <dt>MPLS</dt>
          <dd>Multiprotocol Label Switching.</t>
    <t hangText="PREOF">Packet Switching</dd>
          <dt>PREOF</dt>
          <dd>Packet Replication, Elimination Elimination, and Ordering Functions.</t>
    <t hangText="PSN">Packet Functions</dd>
          <dt>PSN</dt>
          <dd>Packet Switched Network.</t>
    <t hangText="PW">PseudoWire.</t>
    <t hangText="RSVP-TE">Resource Network</dd>
          <dt>PW</dt>
          <dd>Pseudowire</dd>
          <dt>RSVP-TE</dt>
          <dd>Resource Reservation Protocol - Traffic Engineering.</t>
	<t hangText="S-Label">Service label.</t>
    <t hangText="TSN">Time-Sensitive Network.</t>
   </list>
  </t>
  </section>
<!--  <section title="Requirements Language">
   <t>
    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 <xref target="RFC2119"/> <xref target="RFC8174"/> when, and
    only when, they appear in all capitals, as shown here.
   </t> Engineering</dd>
          <dt>S-Label</dt>
          <dd>Service label</dd>
          <dt>TSN</dt>
          <dd>Time-Sensitive Networking</dd>
        </dl>
      </section> -->
 </section>  <!-- end of terminology -->

 <section title="DetNet anchor="sec_dt_dp" numbered="true" toc="default">
      <name>DetNet MPLS Data Plane Overview" anchor="sec_dt_dp"> Overview</name>
      <t>
	The basic approach defined in <xref target="RFC8964"/> target="RFC8964" format="default"/>
	supports the DetNet service sub-layer based on existing pseudowire (PW) PW
	encapsulations and mechanisms, mechanisms and supports the DetNet forwarding
	sub-layer based on existing MPLS Traffic Engineering encapsulations
	and mechanisms.
      </t>
      <t>
  A node operating operates on a DetNet flow in the Detnet DetNet service sub-layer, i.e. i.e.,
  a node processing a DetNet packet which that has the S-Label service label (S-Label) as the top of stack uses
  the local context associated with that service label (S-Label), S-Label, for example example, a received
  forwarding label (F-Label), to determine what local DetNet operation(s) are is applied to that
  packet. An S-Label may be unique when taken from the platform
  label space <xref target="RFC3031"/>, target="RFC3031" format="default"/>, which would enable correct DetNet flow
  identification regardless of which input interface or LSP the packet arrives
  on. The service sub-layer functions (i.e., PREOF) use a DetNet control word
  (d-CW). d-CW.
      </t>
      <t>
    The DetNet MPLS data plane builds on MPLS Traffic Engineering
    encapsulations and mechanisms to provide a forwarding sub-layer that
    is responsible for providing resource allocation and explicit
    routes.  The forwarding sub-layer is supported by one or more
    F-Labels.
      </t>
      <t>
        DetNet edge/relay nodes are DetNet service sub-layer
        aware, sub-layer-aware,
        understand the particular needs of DetNet flows flows, and
        provide both DetNet service and forwarding sub-layer functions.
        They add, remove remove, and process d-CWs, S-Labels S-Labels, and F-labels F-Labels as
        needed.  MPLS DetNet nodes and transit nodes include
        DetNet forwarding sub-layer functions, notably notable support for
        explicit routes, and resources resource allocation to eliminate (or
        reduce) congestion loss and jitter. Unlike other DetNet node types,
		transit nodes provide no service sub-layer processing.
      </t>
      <t>
		MPLS (DetNet) nodes and transit nodes interconnected by a TSN
		sub-network are the primary focus of this document.
		The mapping of DetNet MPLS flows to TSN streams Streams and TSN protection
		mechanisms are covered in <xref target="mpls-over-tsn"/>. target="mpls-over-tsn" format="default"/>.
      </t>
    </section>  <!-- end of data plane overview -->

<!-- ===================================================================== -->

<section anchor="mpls-over-tsn"
         title="DetNet numbered="true" toc="default">
      <name>DetNet MPLS Operation Over over IEEE 802.1 TSN Sub-Networks"> Sub-networks</name>
      <t>
		The DetNet WG collaborates with IEEE 802.1 TSN in order to define a
		common architecture for both Layer 2 and Layer 3, 3 that maintains
		consistency across diverse networks. Both DetNet MPLS and TSN use
		the same techniques to provide their deterministic service:
		<list style="symbols">
			<t>
      </t>
      <ul spacing="normal">
        <li>
				Service protection.
			</t><t> protection
			</li>
        <li>
				Resource allocation.
			</t><t> allocation
			</li>
        <li>
				Explicit routes.
			</t>
		</list> routes
			</li>
      </ul>
      <t>
		As described in the DetNet architecture
		<xref target="RFC8655"/> target="RFC8655" format="default"/>, from the MPLS perspective, a sub-network provides from
		MPLS perspective
	        a single hop single-hop connection between MPLS (DetNet) nodes.
		Functions used for resource allocation and explicit routes
		are treated as domain internal functions and do not require function
		interworking across the DetNet MPLS network and the TSN sub-network.
      </t>
      <t>
		In the case of the service protection function function, due to the similarities of
		the DetNet PREOF and TSN FRER functions functions, some level of interworking is
		possible. However, such interworking is out-of-scope in out of scope of this document
		and left for further study.
      </t>
      <t>
      <xref target="fig_mpls_detnet_to_tsn"/> target="fig_mpls_detnet_to_tsn" format="default"/> illustrates a scenario, scenario where
	  two MPLS (DetNet) nodes are interconnected by a TSN sub-network. Node-1
	  is single homed single-homed, and Node-2 is dual-homed to the TSN sub-network.
      </t>
      <figure align="center" anchor="fig_mpls_detnet_to_tsn"
              title="DetNet Enabled anchor="fig_mpls_detnet_to_tsn">
        <name>DetNet-Enabled MPLS Network Over over a TSN Sub-Network">
<artwork><![CDATA[ Sub-network</name>
        <artwork name="" type="" align="left" alt=""><![CDATA[
   MPLS (DetNet)                 MPLS (DetNet)
      Node-1                        Node-2

   +----------+                  +----------+
<--| Service* |-- DetNet flow ---| Service* |-->
   +----------+                  +----------+
   |Forwarding|                  |Forwarding|
   +--------.-+    <-TSN Str->   +-.-----.--+
             \      ,-------.     /     /
              +----[ TSN-Sub ]---+ TSN Sub-]---+     /
                   [ Network network ]--------+
                    `-------'
<---------------- DetNet MPLS --------------->

Note: * no service sub-layer required for transit nodes
]]></artwork>
      </figure>
      <t>
		At the time of this writing,
		the Time-Sensitive Networking (TSN) Task Group TSN TG of the IEEE 802.1
		Working Group have defined (and are defining) a number of amendments
		to <xref target="IEEE8021Q"/> target="IEEE8021Q" format="default"/> that provide zero
		congestion loss and bounded latency in bridged networks. Furthermore Furthermore,
		<xref target="IEEE8021CB"/> target="IEEE8021CB" format="default"/> defines frame replication
		and elimination functions for reliability that should prove both
		compatible with and useful to, to DetNet networks. All these functions
		have to identify flows those that require TSN treatment (i.e., applying TSN
		functions during forwarding).
      </t>
      <t>
        TSN capabilities of the TSN sub-network are made available for MPLS
        (DetNet) flows via the protocol interworking function defined in Annex C.5 of
        <xref target="IEEE8021CB"/>. target="IEEE8021CB" format="default"/>. For example,
        when applied on the TSN edge port port, it can convert an ingress unicast
		MPLS (DetNet) flow to use a specific Layer-2 Layer 2 multicast destination
		MAC
		Media Access Control (MAC) address and a VLAN, in order to direct the packet through a
		specific path inside the bridged network.
		A similar interworking function pair at the
		other end of the TSN sub-network would restore the packet to its
		original Layer-2 Layer 2 destination MAC address and VLAN.
      </t>
      <t>
        Placement
        The placement of TSN functions depends on the TSN capabilities of the
        nodes along the path. MPLS (DetNet) Nodes nodes may or may not support TSN functions. For
        a given TSN Stream (i.e., DetNet flow) flow), an MPLS (DetNet) node is
        treated as a Talker or a Listener inside the TSN sub-network.
      </t>
      <section title="Functions numbered="true" toc="default">
        <name>Functions for DetNet Flow to TSN Stream Mapping"> Mapping</name>
        <t>
              Mapping of a DetNet MPLS flow to a TSN Stream is provided via
			  the combination of a passive and an active stream Stream identification
			  function that operate at the frame level. The passive stream Stream
			  identification function is used to catch the MPLS label(s) of a
			  DetNet MPLS flow flow, and the active stream Stream identification function
			  is used to modify the Ethernet header according to the ID of the
			  mapped TSN Stream.
        </t>
        <t>
			  Clause 6.8 of <xref target="IEEEP8021CBdb"/> target="IEEEP8021CBdb" format="default"/> defines a
			  Mask-and-Match Stream identification function that can be used
			  as a passive function for MPLS DetNet flows.
        </t>
        <t>
	      Clause 6.6 of <xref target="IEEE8021CB"/> target="IEEE8021CB" format="default"/> defines an
              Active Destination MAC and a VLAN Stream identification function,
              what function
              that can replace some Ethernet header fields fields, namely (1) the
              destination MAC-address, MAC address, (2) the VLAN-ID VLAN-ID, and (3) priority
              parameters with alternate values. Replacement is provided for
              the frame that is passed either down the stack from the upper layers or up the
              stack from the lower layers.
        </t>
        <t>
              Active Destination MAC and VLAN Stream identification can be
              used within a Talker to set flow identity or a Listener to
              recover the original addressing information. It can also be used also
              in a TSN bridge that is providing translation as a proxy service
              for an End System. end system.
        </t>
      </section>
      <section title="TSN requirements numbered="true" toc="default">
        <name>TSN Requirements of MPLS DetNet nodes"> Nodes</name>
        <t>
              This section covers required behavior of a TSN-aware MPLS (DetNet)
			  node using a TSN sub-network. The implementation of TSN packet
			  processing packet-processing
			  functions must be compliant with the relevant IEEE 802.1
			  standards.
        </t>
        <t>
              From the TSN sub-network perspective perspective, MPLS (DetNet) nodes are treated
			  as a Talker or Listener, that which may be (1) TSN-unaware or
			  (2) TSN-aware.
        </t>
        <t>
              In cases of TSN-unaware MPLS DetNet nodes nodes, the TSN relay nodes
			  within the TSN sub-network must modify the Ethernet encapsulation
			  of the DetNet MPLS flow (e.g., MAC translation, VLAN-ID setting,
			  Sequence
			  sequence number addition, etc.) to allow proper TSN specific TSN-specific
			  handling inside the sub-network.  There are no requirements
			  defined for TSN-unaware MPLS DetNet nodes in this document.
        </t>
        <t>
              MPLS (DetNet) nodes being that are TSN-aware can be treated as a
              combination of a TSN-unaware Talker/Listener and a TSN-Relay, as
              shown in <xref target="fig_mpls_with_tsn"/>. target="fig_mpls_with_tsn" format="default"/>.  In such cases cases, the
			  MPLS (DetNet) node must provide the TSN sub-network specific sub-network-specific
			  Ethernet encapsulation over the link(s) towards the sub-network.
        </t>
        <figure align="center" anchor="fig_mpls_with_tsn"
              title="MPLS anchor="fig_mpls_with_tsn">
          <name>MPLS (DetNet) Node with TSN Functions">
<artwork><![CDATA[ Functions</name>
          <artwork name="" type="" align="left" alt=""><![CDATA[
              MPLS (DetNet)
                  Node
   <---------------------------------->

   +----------+
<--| Service* |-- DetNet flow ------------------
   +----------+
   |Forwarding|
   +----------+    +---------------+
   |    L2    |    | L2 Relay with |<--- TSN ---
   |          |    | TSN function  |    Stream
   +-----.----+    +--.------.---.-+
          \__________/        \   \______
                               \_________
    TSN-unaware
     Talker /          TSN-Bridge
     Listener             Relay
                                       <----- TSN Sub-network -----
   <------- TSN-aware Tlk/Lstn ------->

Note: * no service sub-layer required for transit nodes
]]></artwork>
        </figure>
        <t>
			  A TSN-aware MPLS (DetNet) node implementation must support the
			  Stream Identification identification TSN component for recognizing flows.
        </t>
        <t>
              A Stream identification component must be able to instantiate
              the following functions functions: (1) Active Destination MAC and VLAN
              Stream identification function,
			  (2) Mask-and-Match Stream identification function function, and
			  (3) the related managed objects in Clause 9 of
              <xref target="IEEE8021CB"/> target="IEEE8021CB" format="default"/> and
			  <xref target="IEEEP8021CBdb"/>. target="IEEEP8021CBdb" format="default"/>.
        </t>
        <t>
			  A TSN-aware MPLS (DetNet) node implementation must support the
			  Sequencing function and the Sequence encode/decode function as
			  defined in  Clause Clauses 7.4 and 7.6 of <xref target="IEEE8021CB"/> target="IEEE8021CB" format="default"/>
			  in order for FRER to be used inside the TSN sub-network.
        </t>
        <t>
              The Sequence encode/decode function must support the Redundancy
              tag (R-TAG) format as per Clause 7.8 of <xref
              target="IEEE8021CB"/>. target="IEEE8021CB" format="default"/>.
        </t>
        <t>
			  A TSN-aware MPLS (DetNet) node implementation must support the
			  Stream splitting
			  function and the Individual recovery function as defined in
			  Clause 7.7 and
			  Clauses 7.5 and 7.7 of <xref target="IEEE8021CB"/> target="IEEE8021CB" format="default"/>
			  in order for that node to be a replication or elimination
			  point for FRER.
        </t>
      </section>
      <section title="Service protection numbered="true" toc="default">
        <name>Service Protection within the TSN sub-network"> Sub-network</name>
        <t>
              TSN Streams supporting DetNet flows may use Frame Replication
              and Elimination for Redundancy (FRER) FRER as defined in Clause 8. 8 of
			  <xref target="IEEE8021CB"/> target="IEEE8021CB" format="default"/> based on the
              loss service requirements of the TSN Stream, which is derived
              from the DetNet service requirements of the DetNet mapped flow.
              The specific operation of FRER is not modified by the use of
              DetNet and follows <xref target="IEEE8021CB"/>. target="IEEE8021CB" format="default"/>.
        </t>
        <t>
              FRER function and the provided service recovery is available
              only within the TSN sub-network as the TSN Stream-ID and the TSN
              sequence number are not valid outside the sub-network.  An MPLS
              (DetNet) node represents a an L3 border border, and as such such, it terminates
              all related information elements encoded in the L2 frames.
        </t>
        <t>
			  As the Stream-ID and the TSN sequence number are paired with the
			  similar MPLS flow parameters, FRER can be combined with PREOF
			  functions. Such service protection interworking scenarios may
			  require to move moving sequence number fields among TSN (L2) and PW
			  (MPLS) encapsulations encapsulations, and they are left for further study.
        </t>
      </section>
      <section title="Aggregation numbered="true" toc="default">
        <name>Aggregation during DetNet flow Flow to TSN Stream mapping"> Mapping</name>
        <t>
			Implementation of this document shall use management and
			control information to map a DetNet flow to a TSN
			Stream. N:1 mapping (aggregating DetNet flows in a single
			TSN Stream) shall be supported. The management or control
			function that provisions flow mapping shall ensure that
			adequate resources are allocated and configured to provide
			proper service requirements of the mapped flows.
        </t>
      </section>
    </section>

<!-- ============================================================= -->

<section title="Management numbered="true" toc="default">
      <name>Management and Control Implications"> Implications</name>
      <t>
			Information related to DetNet flow and TSN Stream mapping related information are is
			required only for TSN-aware MPLS (DetNet) nodes. From the
			Data Plane perspective
			data plane perspective, there is no practical difference
			based on the origin of flow mapping related flow-mapping-related information
			(management plane or control plane).
      </t>
      <t>
            The following summarizes the set of information that is needed to
            configure DetNet MPLS over TSN:
            <list style="symbols">
			  <t>DetNet MPLS related
      </t>
      <ul spacing="normal">
        <li>DetNet MPLS-related configuration information according to the
			     DetNet role of the DetNet MPLS node, as per
			     <xref target="RFC8964"/>. </t>
			  <t>TSN related target="RFC8964" format="default"/>. </li>
        <li>TSN-related configuration information according to the
			     TSN role of the DetNet MPLS node, as per
				 <xref target="IEEE8021Q"/>, target="IEEE8021Q" format="default"/>, <xref target="IEEE8021CB"/> target="IEEE8021CB" format="default"/>, and
			     <xref target="IEEEP8021CBdb"/>. </t>
              <t>Mapping target="IEEEP8021CBdb" format="default"/>. </li>
        <li>Mapping between a DetNet MPLS flow(s) (label information:
			  A-labels, S-labels
			  A-Labels, S-Labels, and F-labels F-Labels as defined in
			  <xref target="RFC8964"/>) target="RFC8964" format="default"/>) and a TSN
			  Stream(s) (as stream Stream identification information defined in
			  <xref target="IEEEP8021CBdb"/>).
			  Note, target="IEEEP8021CBdb" format="default"/>).
			  Note that managed objects for TSN Stream identification can be
			  found in <xref target="IEEEP8021CBcv"/>.
			  </t>
            </list> target="IEEEP8021CBcv" format="default"/>.
			  </li>
      </ul>
      <t>
            This information must be provisioned per DetNet flow.
      </t>
      <t>
			Mappings between DetNet and TSN management and control planes are
			out of scope of the this document. Some of the challenges are
			highlighted below.
      </t>
      <t>
			TSN-aware MPLS DetNet nodes are members of both the DetNet
			domain and the TSN sub-network.  Within the TSN
			sub-network
			sub-network, the TSN-aware MPLS (DetNet) node has a TSN-aware
			Talker/Listener role, so TSN specific TSN-specific management and
			control plane functionalities must be implemented.  There
			are many similarities in the management plane techniques
			used in DetNet and TSN, but that is not the case for the
			control plane protocols. For example, RSVP-TE and MSRP
			(Multiple the
			Multiple Stream Registration Protocol)
			behaves Protocol (MSRP)
			behave differently. Therefore Therefore, management and control plane
			design is an are important aspect aspects of scenarios, scenarios where
			mapping between DetNet and TSN is required.
      </t>
      <t>
	      In order to use a TSN sub-network between DetNet nodes,
	      DetNet specific
	      DetNet-specific information must be converted to TSN
	      sub-network information specific ones. to the TSN
	      sub-network. DetNet flow ID and flow related flow-related
	      parameters/requirements must be converted to a TSN Stream
	      ID and stream related stream-related parameters/requirements.

	      Note that,
	      as the TSN sub-network is just a portion of the end-2-end end-to-end
	      DetNet path (i.e., a single hop from the MPLS perspective), some
	      parameters (e.g., delay) may differ significantly. Other
	      parameters (like bandwidth) also may have to be tuned due
	      to the L2 encapsulation used within the TSN sub-network.
      </t>
      <t>
	      In some cases cases, it may be challenging to determine some TSN
	      Stream related TSN-Stream-related
	      information. For example, on a TSN-aware MPLS
	      (DetNet) node that acts as a Talker, it is quite obvious
	      which DetNet node is the Listener of the mapped TSN stream Stream
	      (i.e., the MPLS Next-Hop). However next hop). However, it may be not trivial to
	      locate the point/interface where that Listener is
	      connected to the TSN sub-network. Such attributes may
	      require interaction between control and management plane
	      functions and between DetNet and TSN domains.
      </t>
      <t>
	      Mapping between DetNet flow identifiers and TSN Stream
	      identifiers, if not provided explicitly, can be done by a
	      TSN-aware MPLS (DetNet) node locally based on information
	      provided for configuration of the TSN Stream
	      identification functions (Mask-and-match (Mask-and-Match Stream identification
		  and Active active Stream identification function). identification).
      </t>
      <t>
	      Triggering the setup/modification of a TSN Stream in the
	      TSN sub-network is an example where management and/or
	      control plane interactions are required between the DetNet
	      and TSN sub-network. TSN-unaware MPLS (DetNet) nodes make
	      such a triggering even more complicated as they are fully
	      unaware of the sub-network and run independently.
      </t>
      <t>
	      Configuration of TSN specific TSN-specific functions (e.g., FRER)
	      inside the TSN sub-network is a TSN domain specific TSN-domain-specific decision
		  and may not be visible in the DetNet domain. Service protection
		  interworking scenarios are left for further study.
      </t>
    </section>

<!-- ===================================================================== -->

<section title="Security Considerations"> numbered="true" toc="default">
      <name>Security Considerations</name>
      <t>
	  Security considerations for DetNet are described in detail in
	  <xref target="I-D.ietf-detnet-security"/>. target="I-D.ietf-detnet-security" format="default"/>. General security considerations
      are described in <xref target="RFC8655"/>. target="RFC8655" format="default"/>.
	  Considerations specific to the DetNet MPLS data plane specific considerations are summarized in
	  <xref target="RFC8964"/>. target="RFC8964" format="default"/>.
	  This section considers exclusively security considerations which that are
	  specific to the DetNet MPLS over TSN sub-network scenario.
      </t>
      <t>
	  The sub-network between DetNet nodes needs to be subject to appropriate
	  confidentiality. Additionally, knowledge of what DetNet/TSN services are
	  provided by a sub-network may supply information that can be used in a
	  variety of security attacks. The ability to modify information exchanges
	  between connected DetNet nodes may result in bogus operations. Therefore,
	  it is important that the interface between DetNet nodes and the TSN
	  sub-network are subject to authorization, authentication, and encryption.
      </t>
      <t>
	  The TSN sub-network operates at Layer-2 Layer 2, so various security mechanisms
	  defined by IEEE can be used to secure the connection between the DetNet
	  nodes (e.g., encryption may be provided using MACSec MACsec
	  <xref target="IEEE802.1AE-2018"/>). target="IEEE802.1AE-2018" format="default"/>).
      </t>
    </section>
    <section anchor="iana" title="IANA Considerations"> numbered="true" toc="default">
      <name>IANA Considerations</name>
      <t>
      This document makes has no IANA requests.
  </t>
</section>

<section anchor="acks" title="Acknowledgements">
   <t>
		The authors wish to thank Norman Finn, Lou Berger, Craig Gunther,
		Christophe Mangin and Jouni Korhonen for their various contributions
		to this work. actions.
      </t>
    </section>

  </middle>
  <back>
  <references title="Normative References">
<!--   &rfc2119; -->
   <?rfc include="reference.RFC.3031"?>
<!--   <?rfc include="reference.RFC.8174"?> -->
      <?rfc include="reference.RFC.8655"?>
      <?rfc include="reference.RFC.8964"?>

<displayreference target="I-D.ietf-detnet-security" to="DETNET-SECURITY"/>

    <references>
      <name>References</name>
      <references>
        <name>Normative References</name>

	<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.3031.xml"/>
	<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8655.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8964.xml"/>

        <reference anchor="IEEE8021CB"
                 target="http://standards.ieee.org/about/get/"> target="https://ieeexplore.ieee.org/document/8091139">
          <front>
          <title>Standard
            <title>IEEE Standard for Local and metropolitan area networks -
		  Frame networks--Frame Replication and Elimination for Reliability
		  (IEEE Std 802.1CB-2017)</title> Reliability</title>
            <author>
            <organization>IEEE 802.1</organization>
              <organization>IEEE</organization>
            </author>
            <date month="October" year="2017"/>
          </front>
        <format type="PDF" target="http://standards.ieee.org/about/get/"/>
	    <seriesInfo name="DOI" value="10.1109/IEEESTD.2017.8091139"/>
	  <refcontent>IEEE Std 802.1CB-2017</refcontent>
        </reference>

<reference anchor="IEEEP8021CBdb"
                 target="http://www.ieee802.org/1/files/private/db-drafts/d1/802-1CBdb-d1-0.pdf"> target="https://1.ieee802.org/tsn/802-1cbdb/">
          <front>
          <title>Extended
            <title>Draft Standard for Local and metropolitan area networks -—
            Frame Replication and Elimination for Reliability -— Amendment:
            Extended Stream identification functions</title>
          <author initials="C. M." surname="Mangin" fullname="Christophe Mangin">
            <organization>IEEE 802.1</organization> Identification Functions</title>
            <author>
              <organization>IEEE</organization>
            </author>
            <date month="September" year="2020"/> month="April" year="2021"/>
          </front>
        <seriesInfo name="IEEE
	 <refcontent>IEEE P802.1CBdb /D1.0" value="P802.1CBdb"/>
        <format type="PDF" target="http://www.ieee802.org/1/files/private/db-drafts/d1/802-1CBdb-d1-0.pdf"/> / D1.3</refcontent>
        </reference>
      </references>
  <references title="Informative References">
      <references>

        <name>Informative References</name>

<!--      <?rfc include="reference.I-D.ietf-detnet-ip"?> [I-D.ietf-detnet-security-15] RFC-EDITOR  -->
      <?rfc include="reference.I-D.ietf-detnet-security"?>
      <xi:include href="https://datatracker.ietf.org/doc/bibxml3/reference.I-D.ietf-detnet-security.xml"/>

        <reference anchor="IEEE802.1AE-2018" target="https://ieeexplore.ieee.org/document/8585421">
          <front>
            <title>IEEE Std 802.1AE-2018 MAC Security (MACsec)</title> Standard for Local and metropolitan area networks-Media Access Control (MAC) Security</title>
            <author>
          <organization>IEEE Standards Association</organization>
              <organization>IEEE</organization>
            </author>
            <date year="2018" /> month="December" year="2018"/>
          </front>
	  <seriesInfo name="DOI" value="10.1109/IEEESTD.2018.8585421"/>
	  <refcontent>IEEE Std 802.1AE-2018</refcontent>
        </reference>

        <reference anchor="IEEE8021Q"
                 target="http://standards.ieee.org/about/get/"> target="https://ieeexplore.ieee.org/document/8403927/">
          <front>
          <title>Standard
            <title>IEEE Standard for Local and metropolitan area networks--Bridges
          and Bridged Networks (IEEE Std 802.1Q-2018)</title> Networks</title>
            <author>
            <organization>IEEE 802.1</organization>
              <organization>IEEE</organization>
            </author>
            <date month="July" year="2018"/>
          </front>
        <format type="PDF" target="http://standards.ieee.org/about/get/"/>
	   <seriesInfo name="DOI" value="10.1109/IEEESTD.2018.8403927"/>
	   <refcontent>IEEE Std 802.1Q-2018</refcontent>
        </reference>

        <reference anchor="IEEEP8021CBcv"
                 target="https://www.ieee802.org/1/files/private/cv-drafts/d0/802-1CBcv-d0-4.pdf"> target="https://1.ieee802.org/tsn/802-1cbcv/">
          <front>
          <title>FRER
            <title>Draft Standard for Local and metropolitan area networks -- Frame Replication and Elimination for Reliability -- Amendment: Information Model, YANG Data Model and Management Information Base Module</title>
          <author initials="S." surname="Kehrer" fullname="Stephan Kehrer">
            <author>
              <organization>IEEE 802.1</organization>
            </author>
            <date month="August" year="2020"/> month="February" year="2021"/>
          </front>
        <seriesInfo name="IEEE P802.1CBcv /D0.4" value="P802.1CBcv"/>
        <format type="PDF" target="https://www.ieee802.org/1/files/private/cv-drafts/d0/802-1CBcv-d0-4.pdf"/>
	  <refcontent>IEEE P802.1CBcv, Draft 1.1</refcontent>
        </reference>
      </references>
    </references>

       <section anchor="acks" numbered="false" toc="default">
      <name>Acknowledgements</name>
      <t>
		The authors wish to thank <contact fullname="Norman Finn"/>,  <contact fullname="Lou Berger"/>,  <contact fullname="Craig Gunther"/>,
		 <contact fullname="Christophe Mangin"/>, and  <contact fullname="Jouni Korhonen"/> for their various contributions
		to this work.
      </t>
    </section>
  </back>
</rfc>