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Versions: 00 01 02 03 04                                                
Network Working Group                                            X. Geng
Internet-Draft                                                   J. Dong
Intended status: Informational                       Huawei Technologies
Expires: 28 April 2022                                           R. Pang
                                                            China Unicom
                                                                  L. Han
                                                            China Mobile
                                                                R. Rokui
                                                                   Nokia
                                                                 T. Niwa
                                                              Individual
                                                                  J. Jin
                                                                   LG U+
                                                                  C. Liu
                                                            China Unicom
                                                             N. Nageshar
                                                              Individual
                                                         25 October 2021


 5G End-to-end Network Slice Mapping from the view of Transport Network
                draft-geng-teas-network-slice-mapping-04

Abstract

   Network Slicing is one of the core features in 5G.  End-to-end
   network slice consists of 3 major types of network segments: Access
   Network (AN), Mobile Core Network (CN) and Transport Network (TN).
   This draft describes the procedure of mapping 5G end-to-end network
   slice to transport network slice defined in IETF.  This draft also
   intends to expose some gaps in the existing network management plane
   and data plane technologies to support inter-domain network slice
   mapping.  Further work may require collaboration between IETF and
   3GPP (or other standard organizations).  Data model specification,
   signaling protocol extension and new encapsulation definition are out
   of the scope of this draft.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

Status of This Memo

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




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   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on 28 April 2022.

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   Copyright (c) 2021 IETF Trust and the persons identified as the
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   Please review these documents carefully, as they describe your rights
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   provided without warranty as described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Terminologies . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  5G End-to-End Network Slice Identification  . . . . . . . . .   4
   4.  Network Slice Mapping Structure . . . . . . . . . . . . . . .   5
   5.  Network Slice Mapping Procedure . . . . . . . . . . . . . . .   8
     5.1.  Network Slice Mapping in Management Plane . . . . . . . .   9
     5.2.  Network Slice Mapping in Control Plane  . . . . . . . . .  10
     5.3.  Network Slice Mapping in Data Plane . . . . . . . . . . .  10
       5.3.1.  Data Plane Mapping Considerations . . . . . . . . . .  10
       5.3.2.  Data Plane Mapping Options  . . . . . . . . . . . . .  11
   6.  Network Slice Mapping Summary . . . . . . . . . . . . . . . .  15
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  16
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  16
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  16
   10. Normative References  . . . . . . . . . . . . . . . . . . . .  16
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  18







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1.  Introduction

   Driven by the new applications of 5G, the concept of network slicing
   is defined to provide a logical network with specific capabilities
   and characteristics.  Network slice contains a set of network
   functions and allocated resources(e.g. computation, storage and
   network resources).  According to [TS28530], a 5G end-to-end network
   slice is composed of three major types network segments: Radio Access
   Network (RAN), Transport Network (TN) and Mobile Core Network (CN).
   Transport network is supposed to provide the required connectivity
   between AN and CN, with specific performance commitment.  For each
   end-to-end network slice, the topology and performance requirement
   for transport network can be very different, which requests transport
   network to have the capability of supporting multiple different
   transport network slices.

   The concept of IETF network slice is discussed in
   [I-D.ietf-teas-ietf-network-slices].  In summary, an IETF Network
   Slice is a logical network topology connecting a number of endpoints
   using a set of shared or dedicated network resources that are used to
   satisfy specific Service Level Objectives SLOs) and Service Level
   Expectations (SLEs).

   The realization of an IETF network slices in Transport network (TN)
   could span multiple technology (e.g., IP/MPLS, Optical) and multiple
   administrative domains.  Depending on the consumer's requirement, an
   IETF network slice could be isolated from other concurrent IETF
   network slices, in terms of data plane, control plane and management
   plane.  The procedure for lifecycle of an end-to-end network slice
   instance (i.e., creation, deletion, modificatinon, termination etc.)
   is defined in [TS28531].  End-to-end network slicing provisioning is
   specified in ETSI [ZSM003].  But there is no specifications about how
   to map end-to-end network slice to IETF network slices in Transport
   Network (TN).  This draft describes the procedure of mapping the 5G
   end-to-end network slice to IETF network slices in management plane,
   control plane and data plane.

2.  Terminologies

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

   The following terms are used in this document:

   NSC: IETF Network Slice Controller

   NSI: Network Slice Instance



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   NSSI: Network Slice Subnet Instance

   S-NSSAI: Single Network Slice Selection Assistance Information

   AN: Access Network

   RAN: Radio Access Network

   TN: Transport Network

   CN: Mobile Core Network

   DSCP: Differentiated Services Code Point

   CSMF: Communication Service Management Function

   NSMF: Network Slice Management Function

   NSSMF: Network Slice Subnet Management Function

3.  5G End-to-End Network Slice Identification

   The following figure illustrates a typical mobile network with three
   5G e2e network slices.  Each e2e network slice contains AN slice, CN
   slice and one or more IETF network Slices. 3GPP identifies each e2e
   network slice using an integer called S-NSSAI.  In Figure-1 there are
   three instances of e2e network slices which are identified by S-NSSAI
   01111111, 02222222 and 02333333, respectively.  Each instance of e2e
   network slice contains AN slice, CN Slice and one or more IETF
   network slices.  For example, e2e network slice 01111111 has AN Slice
   instance 4, CN Slice instance 1 and IETF network slice 6.  Note that
   3GPP does not cover the IETF network slice.  See [I-D.ietf-teas-ietf-
   network-slices] for details of IETF network slice.

   Note that 3GPP uses the terms NSI and NSSI which are a set of network
   function and required resources (e.g. compute, storage and networking
   resources) which corresponds to network slice Instance, whereas
   S-NSSAI is an integer that identifies the e2e network slice.













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               +-----------+ +-----------+  +-----------+
               |  S-NSSAI  | |  S-NSSAI  |  |  S-NSSAI  |
               |  01111111 | |  02222222 |  |  03333333 |
               +---|-------+ +---|---|---+  +----|------+
                   |  +----------+   |           |
                   V  V              V           V
                 *******       ********      ********
   Core         * NSSI 1 *    * NSSI 2 *    * NSSI 3 *
   Network       ********      ********      ********
                     \              \             /
                      \              \           /
                      +-----+       +-----+    +-----+
   Transport          | IETF|       | IETF|    | IETF|
   Network            | NS 6|       | NS 7|    | NS 8|
                      +-----+       +-----+    +-----+
                          \              \   /
                           \              \ /
                           ********     ********
    Access                * NSSI 4 *   * NSSI 5 *
    Network                ********     ********


   Figure 1 5G End-to-End Network Slice and its components

4.  Network Slice Mapping Structure

   Referring to 3GPP TR 28.801, the management of 5G e2e network slices
   from 3GPP view is shown in Figure-2(A).  Figure-2(B) illustrates the
   view of IETF and how it maps to 3GPP network slice management.  In
   particular, the IETF network slice controller (NSC) is equivalent to
   3GPP TN NSSMF and functional block "Consumer" at IETF is equivalent
   to 3GPP NSMF.



















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                   +-----------------+
                   |       NSMF      |
                   +-----------------+
        +----------|     S-NSSAI     |----------+
        |          |(e.g. 011111111) |          |
        |          +-----------------+          |
        |                   |                   |
        V                   V                   V
 +-------------+ +---------------------+ +-------------+
 |  AN NSSMF   | |       IETF NSC      | |   CN NSSMF  |
 +-------------+ +---------------------+ +-------------+
 |   AN Slice  | | IETF Network Slice  | |   CN Slice  |
 | Identifier  | |     Identifier      | |  Identifier |
 | (e.g., 4)   | |     (e.g., 6)       | |  (e.g., 1)  |    Management
 +-------------+ +---------------------+ +-------------+      Plane
      |           |                   |           |      -----------------
      |           |                   |           |
      V           V                   V           V      -----------------
      /\       +-----+             +-----+    +-------+        Data
     /AN\ -----|  PE |-----...-----| PE  |----|  CN   |        Plane
    /____\     +-----+             +-----+    +-------+

Note: Refer to Figure-1 for S-NSSAI 01111111, AN, CN and IETF networks slices 4,6 and 1

Figure-2 Relation between IETF and 3GPP Network Slice management

   The following figure shows the necessary elements for mapping end-to-
   end network slice into IETF network slices.























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        +---------------------+
        |         CSMF        |
        +----------|----------+
                   |                    +------------------------+
        +---------------------+         |  5G E2E Network Slice  |
        |         NSMF        |         |      Orchestrator      |
        +---------------------+         +------------------------+
              /    |    \                            |
             /     |     \                  NSC NBI  |
            /      |      \                          |
   +---------++---------++---------+    +------------------------+
   |    AN   ||    TN   ||   CN    |    |   IETF Network Slice   |
   |   NSSMF ||   NSSMF ||  NSSMF  |    |     Controller (NSC)   |
   |         ||         ||         |    +------------------------+
   +---------++---------++---------+         NSC SBI |
        |          |          |                      |
        |          |          |         +------------------------+
        |          |          |         |    Network Controllers |
        |          |          |         +------------------------+
        |          |          |                      |
        |          |          |                      |
      ******      ******     ******               ******
     *  5G  *    * IETF *   *  5G  *             * IETF *
    *   RAN  *  * Network* *  Core  *           * Network*
     *      *    *      *   *      *             *      *
      ******      ******     ******               ******

   Figure-3 5G E2E Network Slice Mapping Structure

   The following network slice related identifiers in management plane,
   control plane and data(user) plane play an important role in end-to-
   end network slice mapping.

   *  Single Network Slice Selection Assistance Information(S-NSSAI):
      The end-to-end network slice identifier, which is defined in
      [TS23501]; S-NSSAI is used during 3GPP network slice signalling
      process.

   *  IETF Network Slice Identifier: An identifier allocated by IETF
      Neetwork Slice Controller (NSC) in management plane.  In data
      plane, IETF Network Slice Identifier may be instantiated with
      existing data plane identifiers and doesn't necessarily require
      new encapsulation.








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   *  IETF Network Slice Interworking Identifier: Data-plane network
      slice identifier which is used for mapping the end-to-end network
      slice traffic to specific IETF network slice.  The IETF Network
      Slice Interworking Identifier is a new concept introduced by this
      draft, which may be instantiated with existing data plane
      identifiers and doesn't necessarily require new encapsulation.

   The relationship between these identifiers are specifies in the
   following sections.


5.  Network Slice Mapping Procedure

   This section provides a general procedure of network slice mapping:

   1.  NSMF receives the request from CSMF for allocation of a network
   slice instance with certain characteristics.

   2.  Based on the service requirement , NSMF acquires requirements for
   the end-to-end network slice instance , which is defined in Service
   Profile([TS28541] section 6.3.3).

   3.  Based on Service Profile, NSMF identified the network function
   and the required resources in AN, CN and TN networks.  It also
   assigns the unique ID S-NSSAI.

   4.  NSMF sends a request to AN NSSMF for creation of AN Slice.

   5.  NSMF sends a request to CN NSSMF for creation of CN Slice.

   6.  NSMF sends a request to IETF Network Slice Controller (NSC) for
   creation of IETF Network Slice.  The request contains such attribute
   such as endpoints, required SLA/SLO along with other IETF network
   slice attributes.  It also cotains mapping informatin for IETF
   Network Slice Interworking Identifier.

   7.  NSC realizes the IETF network slice which satisfies the
   requirement of IETF network slice between the specified endpoints
   (AN/ CN edge nodes).  It assigns sliceID and send it to NSMF.

   8.  NSMF has the mapping relationship between S-NSSAI and IETF
   Network Slice ID;

   9.  When the User Equipment (UE) appears, and during the 5G
   signalling, it requests to be connected to specific e2e network slice
   identified by S-NASSI.  Then a GTP tunnel (which is UDP/IP) will be
   created.




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   10.  UE starts sending traffic in context of e2e network slice for
   specific S-NASSI.

   11.  In context of GTP tunnel, the AN edge nodes encapsulates the
   packet with sliceIID according to the selected S-NSSAI ans send it to
   the transport network.

   12.  The transport network edge node receives the IP packet and
   parses the sliceIID from the packet and maps the packet to the
   corresponding IETF network slice.  It may encapsulate packet with
   sliceID if needed (for example for enforcing QoS in transport
   network).

5.1.  Network Slice Mapping in Management Plane

   The transport network management Plane maintains the interface
   between NSMF and TN NSSMF, which 1) guarantees that IETF network
   slice could connect the AN and CN with specified characteristics that
   satisfy the requirements of communication; 2) builds up the mapping
   relationship between NSI identifier and TN NSSI identifier; 3)
   maintains the end-to-end slice relevant functions;

   Service Profile defined in[TS28541] represents the requirement of
   end-to-end network slice instance in 5G network.  Parameters defined
   in Service Profile include Latency, resource sharing level,
   availability and so on.  How to decompose the end-to-end requirement
   to the transport network requirement is one of the key issues in
   Network slice requirement mapping.  GSMA(Global System for Mobile
   Communications Association) defines the [GST] to indicate the network
   slice requirement from the view of service provider.
   [I-D.contreras-teas-slice-nbi] analysis the parameters of GST and
   categorize the parameters into three classes, including the
   attributes with direct impact on the IETF network slice definition.
   It is a good start for selecting the transport network relevant
   parameters in order to define Network Slice Profile for Transport
   Network.  Network slice requirement parameters are also necessary for
   the definition of transport network northbound interface.

   Inside the TN NSSMF, it is supposed to maintain the attributes of the
   IETF network slice.  If the attributes of an existing TN NSSI could
   satisfy the requirement from TN Network Slice Profile, the existing
   TN NSSI could be selected and the mapping is finished If there is no
   existing TN NSSI which could satisfy the requirement, a new TN NSSI
   is supposed to be created by the NSSMF with new attributes.

   TN NSSI resource reservation should be considered to avoid over
   allocation from multiple requests from NSMF (but the detailed
   mechanism should be out of scope in the draft)



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   TN NSSMF sends the selected or newly allocated TN NSSI identifier to
   NSMF.  The mapping relationship between NSI identifier and TN NSSI
   identifier is maintained in both NSMF and TN NSSMF.

   YANG data model for the Transport Slice NBI, which could be used by a
   higher level system which is the Transport slice consumer of a
   Transport Slice Controller (TSC) to request, configure, and manage
   the components of a transport slices, is defined in
   [I-D.wd-teas-transport-slice-yang].  The northbound Interface of IETF
   network slice refers to [I-D.wd-teas-ietf-network-slice-nbi-yang].

5.2.  Network Slice Mapping in Control Plane

   There is no explicit interaction between transport network and AN/CN
   in the control plane, but the S-NSSAI defined in [TS23501] is treated
   as the end-to-end network slice identifier in the control plane of AN
   and CN, which is used in UE registration and PDU session setup.  In
   this draft, we assume that there is mapping relationship between
   S-NSSAI and NSI in the management plane, thus it could be mapped to a
   IETF network slice .

   Editor's note: The mapping relationship between NSI defined in
   [TS23501] and S-NSSAI defined in [TS23501] is still in discussion.

5.3.  Network Slice Mapping in Data Plane

   If multiple network slices are carried through one physical interface
   between AN/CN and TN, IETF Network Slice Interworking ID in the data
   plane needs to be introduced.  If different network slices are
   transported through different physical interfaces, Network Slices
   could be distinguished by the interface directly.  Thus IETF Network
   Slice Interworking ID is not the only option for network slice
   mapping, while it may help in introducing new network slices.

5.3.1.  Data Plane Mapping Considerations

   The mapping relationship between AN or CN network slice identifier
   (either S-NSSAI in control plane or NSI/NSSI in management plane) and
   IETF Network Slice Interworking ID needs to be maintained in AN/CN
   network nodes, and the mapping relationship between IETF Network
   Slice Interworking ID and IETF Network Slice is maintained in the
   edge node of transport network.  When the packet of a uplink flow
   goes from AN to TN, the packet is encapsulated based on the IETF
   Network Slice Interworking ID; then the encapsulation of IETF Network
   Slice Interworking ID is read by the edge node of transport network,
   which maps the packet to the corresponding IETF network slice.





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   Editor's Note: We have considered to add "Network Instance" defined
   in [TS23501]in the draft.  However, after the discussion with 3GPP
   people, we think the concept of "network instance" is a 'neither
   Necessary nor Sufficient Condition' for network slice.  Network
   Instance could be determined by S-NSSAI, it could also depends on
   other information; Network slice could also be allocated without
   network instance (in my understanding) And, IETF Network Slice
   Interworking ID is not a competitive concept with network
   instance.IETF Network Slice Interworking ID is a concept for the data
   plane interconnection with transport network, network instance may be
   used by AN and CN nodes to associate a network slice with IETF
   Network Slice Interworking ID

5.3.2.  Data Plane Mapping Options

   The following picture shows the end-to-end network slice in data
   plane:

   +--+       +-----+                           +----------------+
   |UE|- - - -|(R)AN|---------------------------|       UPF      |
   +--+       +-----+                           +----------------+
    |<----AN NS---->|<----------TN NS---------->|<----CN NS----->|

   The mapping between 3GPP slice and transport slice in user plane
   could happens in:

   (R)AN: User data goes from (radio) access network to transport
   network

   UPF: User data goes from core network functions to transport network

   Editor's Note: As figure 4.7.1. in [TS28530] describes, TN NS will
   not only exist between AN and CN but may also within AN NS and CN NS.
   However, here we just show the TN between AN and CN as an example to
   avoid unncessary complexity.

   The following picture shows the user plane protocol stack in end-to-
   end 5G system.













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  +-----------+                    |                  |               |
  |Application+--------------------|------------------|---------------|
  +-----------+                    |                  | +-----------+ |
  | PDU Layer +--------------------|------------------|-| PDU Layer | |
  +-----------+   +-------------+  |  +-------------+ | +-----------+ |
  |           |   | ___Relay___ |--|--| ___Relay___ |-|-|           | |
  |           |   |     \/ GTP-U|--|--|GTP-U\/ GTP-U|-|-|   GTP-U   | |
  |   5G-AN   |   |5G-AN +------+  |  +------+------+ | +-----------+ |
  |  Protocol |   |Protoc|UDP/IP|--|--|UDP/IP|UDP/IP|-|-|   UDP/IP  | |
  |   Layers  |   |Layers+------+  |  +------+------+ | +-----------+ |
  |           |   |      |  L2  |--|--|  L2  |  L2  |-|-|     L2    | |
  |           |   |      +------+  |  +------+------+ | +-----------+ |
  |           |   |      |  L1  |--|--|  L1  |  L1  |-|-|     L1    | |
  +-----------+   +-------------+  |  +-------------+ | +-----------+ |
       UE              5G-AN       |        UPF       |      UPF      |
                                   N3                 N9              N6

   The following figure shows the typical encapsulation in N3 interface
   which could be used to carry the IETF Network Slice Interworking ID
   between AN/CN and TN.

   +------------------------+
   | Application Protocols  |
   +------------------------+
   |       IP (User)        |
   +------------------------+
   |          GTP           |
   +------------------------+
   |          UDP           |
   +------------------------+
   |          IP            |
   +------------------------+
   |       Ethernet         |
   +------------------------+

5.3.2.1.  Layer 3 and Layer 2 Encapsulations

   If the encapsulation above IP layer is not visible to Transport
   Network, it is not able to be used for network slice interworking
   with transport network.  In this case, IP header and Ethernet header
   could be considered to provide information of network slice
   interworking from AN or CN to TN.









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   +------------------------+-----------
   | Application Protocols  |      ^
   +------------------------+      |
   |       IP (User)        |  Invisible
   +------------------------+     for
   |          GTP           |     TN
   +------------------------+      |
   |          UDP           |      V
   +------------------------+------------
   |          IP            |
   +------------------------+
   |       Ethernet         |
   +------------------------+

   The following field in IP header and Ethernet header could be
   considered :

   IP Header:

   *  DSCP: It is traditionally used for the mapping of QoS identifier
      between AN/CN and TN network.  Although some values (e.g.  The
      unassigned code points) may be borrowed for the network slice
      interworking, it may cause confusion between QoS mapping and
      network slicing mapping.;

   *  Destination Address: It is possible to allocate different IP
      addresses for entities in different network slice, then the
      destination IP address could be used as the network slice
      interworking identifier.  However, it brings additional
      requirement to IP address planning.  In addition, in some cases
      some AN or CN network slices may use duplicated IP addresses.

   *  Option fields/headers: It requires that both AN and CN nodes can
      support the encapsulation and decapsulation of the options.

   Ethernet header

   *  VLAN ID: It is widely used for the interconnection between AN/CN
      nodes and the edge nodes of transport network for the access to
      different VPNs.  One possible problem is that the number of VLAN
      ID can be supported by AN nodes is typically limited, which
      effects the number of IETF network slices a AN node can attach to.
      Another problem is the total amount of VLAN ID (4K) may not
      provide a comparable space as the network slice identifiers of
      mobile networks.






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   Two or more options described above may also be used together as the
   IETF Network Slice Interworking ID, while it would make the mapping
   relationship more complex to maintain.

   In some other case, when AN or CN could support more layer 3
   encapsulations, more options are available as follows:

   If the AN or CN could support MPLS, the protocol stack could be as
   follows:

   +------------------------+-----------
   | Application Protocols  |      ^
   +------------------------+      |
   |       IP (User)        |  Invisible
   +------------------------+     for
   |          GTP           |     TN
   +------------------------+      |
   |          UDP           |      V
   +------------------------+------------
   |         MPLS           |
   +------------------------+
   |          IP            |
   +------------------------+
   |       Ethernet         |
   +------------------------+

   A specified MPLS label could be used to as a IETF Network Slice
   Interworking ID.

   If the AN or CN could support SRv6, the protocol stack is as follows:

   +------------------------+-----------
   | Application Protocols  |      ^
   +------------------------+      |
   |       IP (User)        |  Invisible
   +------------------------+     for
   |          GTP           |     TN
   +------------------------+      |
   |          UDP           |      V
   +------------------------+------------
   |          SRH           |
   +------------------------+
   |         IPv6           |
   +------------------------+
   |       Ethernet         |
   +------------------------+

   The following field could be considered to identify a network slice:



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   SRH:

   *  SRv6 functions: AN/CN is supposed to support the new function
      extension of SRv6.

   *  Optional TLV: AN/CN is supposed to support the extension of
      optional TLV of SRH.

5.3.2.2.  Above Layer 3 Encapsulations

   If the encapsulation above IP layer is visible to Transport Network,
   it is able to be used to identify a network slice.  In this case, UPD
   and GTP-U could be considered to provide information of network slice
   interworking between AN or CN and TN.

   +------------------------+----------
   | Application Protocols  |     |
   +------------------------+ Invisible
   |       IP (User)        |     for
   +------------------------+     TN
   |          GTP           |     |
   +------------------------+------------
   |          UDP           |
   +------------------------+
   |          IP            |
   +------------------------+
   |       Ethernet         |
   +------------------------+

   The following field in UDP header could be considered:

   UDP Header:

   *  UDP Source port: The UDP source port is sometimes used for load
      balancing.  Using it for network slice mapping would require to
      disable the load-balancing behavior.

6.  Network Slice Mapping Summary

   The following picture shows the mapping relationship between the
   network slice identifier in management plane, control plane and user
   plane.









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                 AN/CN            |              TN
   Management +---------+         |   +-----------------------+
     Plane    |   NSI   |<--------|-->| IETF Network Slice ID |
              +---------+         |   +-----------------------+
                   |              |             |
                   |              |             |
    Control  +-----V-----+        |  +----------+----------+
     Plane   |  S-NSSAI  |        |  |                     |
             +-----------+        |  |                     |
                   |            +----V----+           +----V-------+
                   +----------->|  IETF   |<--------->| IETF       |
     Data                       | Network |<--------->| Network    |
     Plane                      | Slice   |           | Slice      |
                                | InterID |           |realization |
                                +---------+           +------------+

7.  IANA Considerations

   TBD

   Note to RFC Editor: this section may be removed on publication as an
   RFC.

8.  Security Considerations

   TBD

9.  Acknowledgements

   The authors would like to thank Shunsuke Homma for reviewing the
   draft and giving valuable comments.

10.  Normative References

   [GST]      "Generic Network Slice Template",
              <https://www.gsma.com/newsroom/all-documents/generic-
              network-slice-template-v2-0/>.

   [I-D.contreras-teas-slice-nbi]
              Contreras, L. M., Homma, S., Ordonez-Lucena, J. A.,
              Tantsura, J., and K. Szarkowicz, "IETF Network Slice Use
              Cases and Attributes for Northbound Interface of IETF
              Network Slice Controllers", Work in Progress, Internet-
              Draft, draft-contreras-teas-slice-nbi-05, 12 July 2021,
              <https://www.ietf.org/archive/id/draft-contreras-teas-
              slice-nbi-05.txt>.





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   [I-D.ietf-teas-ietf-network-slice-definition]
              Rokui, R., Homma, S., Makhijani, K., Contreras, L. M., and
              J. Tantsura, "Definition of IETF Network Slices", Work in
              Progress, Internet-Draft, draft-ietf-teas-ietf-network-
              slice-definition-01, 22 February 2021,
              <https://www.ietf.org/archive/id/draft-ietf-teas-ietf-
              network-slice-definition-01.txt>.

   [I-D.ietf-teas-ietf-network-slices]
              Farrel, A., Gray, E., Drake, J., Rokui, R., Homma, S.,
              Makhijani, K., Contreras, L. M., and J. Tantsura,
              "Framework for IETF Network Slices", Work in Progress,
              Internet-Draft, draft-ietf-teas-ietf-network-slices-04, 23
              August 2021, <https://www.ietf.org/archive/id/draft-ietf-
              teas-ietf-network-slices-04.txt>.

   [I-D.wd-teas-ietf-network-slice-nbi-yang]
              Wu, B., Dhody, D., Rokui, R., Saad, T., Han, L., and L. M.
              Contreras, "IETF Network Slice Service YANG Model", Work
              in Progress, Internet-Draft, draft-wd-teas-ietf-network-
              slice-nbi-yang-05, 26 September 2021,
              <https://www.ietf.org/archive/id/draft-wd-teas-ietf-
              network-slice-nbi-yang-05.txt>.

   [I-D.wd-teas-transport-slice-yang]
              Wu, B., Dhody, D., Han, L., and R. Rokui, "A Yang Data
              Model for Transport Slice NBI", Work in Progress,
              Internet-Draft, draft-wd-teas-transport-slice-yang-02, 12
              July 2020, <https://www.ietf.org/archive/id/draft-wd-teas-
              transport-slice-yang-02.txt>.

   [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>.

   [TS23501]  "3GPP TS23.501",
              <https://portal.3gpp.org/desktopmodules/Specifications/
              SpecificationDetails.aspx?specificationId=3144>.

   [TS28530]  "3GPP TS28.530",
              <https://portal.3gpp.org/desktopmodules/Specifications/
              SpecificationDetails.aspx?specificationId=3273>.

   [TS28531]  "3GPP TS28.531",
              <https://portal.3gpp.org/desktopmodules/Specifications/
              SpecificationDetails.aspx?specificationId=3274>.




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   [TS28541]  "3GPP TS 28.541",
              <https://portal.3gpp.org/desktopmodules/Specifications/
              SpecificationDetails.aspx?specificationId=3400>.

   [ZSM003]   "ETSI ZSM003",
              <https://portal.3gpp.org/desktopmodules/Specifications/
              SpecificationDetails.aspx?specificationId=3144>.

Authors' Addresses

   Xuesong Geng
   Huawei Technologies

   Email: gengxuesong@huawei.com


   Jie Dong
   Huawei Technologies

   Email: jie.dong@huawei.com


   Ran Pang
   China Unicom

   Email: pangran@chinaunicom.cn


   Liuyan Han
   China Mobile

   Email: hanliuyan@chinamobile.com


   Reza Rokui
   Nokia

   Email: reza.rokui@nokia.com


   Tomonobu Niwa
   Individual

   Email: tomonobu.niwa@gmail.com







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   Jaehwan Jin
   LG U+

   Email: daenamu1@lguplus.co.kr


   Chang Liu
   China Unicom

   Email: liuc131@chinaunicom.cn


   Nikesh Nageshar
   Individual

   Email: nikesh.nageshar@gmail.com



































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