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Versions: (draft-dbwb-opsawg-sap) 00 01 02 03 04         Standards Track
          05 06 07                                                      
OPSAWG                                                 M. Boucadair, Ed.
Internet-Draft                                                    Orange
Intended status: Standards Track                     O. Gonzalez de Dios
Expires: 21 November 2022                                     S. Barguil
                                                              Telefonica
                                                                   Q. Wu
                                                                  Huawei
                                                                V. Lopez
                                                                   Nokia
                                                             20 May 2022


       A Network YANG Model for Service Attachment Points (SAPs)
                        draft-ietf-opsawg-sap-07

Abstract

   This document defines a YANG data model for representing an abstract
   view of the provider network topology that contains the points from
   which its services can be attached (e.g., basic connectivity, VPN,
   network slices).  Also, the model can be used to retrieve the points
   where the services are actually being delivered to customers
   (including peer networks).

   This document augments the 'ietf-network' data model by adding the
   concept of Service Attachment Points (SAPs).  The SAPs are the
   network reference points to which network services, such as Layer 3
   Virtual Private Network (L3VPN) or Layer 2 Virtual Private Network
   (L2VPN), can be attached.  Both User-Network Interface (UNI) and
   Network-to-Network Interface (NNI) are supported in the SAP data
   model.

Status of This Memo

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

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

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 21 November 2022.



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Copyright Notice

   Copyright (c) 2022 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 (https://trustee.ietf.org/
   license-info) 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 Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  SAP Network Model Usage . . . . . . . . . . . . . . . . . . .   4
   4.  Relationship to Other YANG Data Models  . . . . . . . . . . .   8
   5.  SAP Module Tree Structure . . . . . . . . . . . . . . . . . .   9
   6.  SAP YANG Module . . . . . . . . . . . . . . . . . . . . . . .  12
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  19
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  19
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  20
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  20
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  20
     10.2.  Informative References . . . . . . . . . . . . . . . . .  22
   Appendix A.  A Simplified SAP Network Example . . . . . . . . . .  25
   Appendix B.  A Simple Example of SAP Network Model: Node
           Filter  . . . . . . . . . . . . . . . . . . . . . . . . .  28
   Appendix C.  An Example of NNI SAP: Inter-AS VPN Option A . . . .  32
   Appendix D.  An Example of Using the SAP Network Model in Service
           Creation  . . . . . . . . . . . . . . . . . . . . . . . .  35
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  36

1.  Introduction

   Service providers offer a variety of network services to their
   customers.  Such services include, but are not limited to, Virtual
   Private Networks (VPNs), Software-Defined Wide Area Network (SDWAN)
   [I-D.ietf-bess-bgp-sdwan-usage], and network slices
   [I-D.ietf-teas-ietf-network-slices].  In order to rationalize the
   overall service operations and allow for more automated service
   provisioning procedures, service providers need to maintain a view on
   where services can be delivered to customers.  Such view can be used,
   e.g., to feed an intelligence that is responsible for service order
   handling, service feasibility checks, tracking per-service coverage,



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   etc.  To that aim, this document introduces the concept of Service
   Attachment Points (SAPs).

   The SAPs represent the network reference points where network
   services can be delivered to customers.  For example, this concept is
   used to decide where to attach and, thus, deliver the service in the
   Layer 3 VPN Service Model (L3SM) [RFC8299] and the Layer 2 VPN
   Service Model (L2SM) [RFC8466].  It can also be used to retrieve
   where services, such as the Layer 3 VPN Network Model (L3NM)
   [RFC9182] and the Layer 2 VPN Network Model (L2NM)
   [I-D.ietf-opsawg-l2nm], are delivered to customers.

   This document defines a YANG network model (Section 6) for
   representing, managing, and controlling the SAPs.  The data model
   augments the 'ietf-network' module [RFC8345] by adding the concept of
   SAPs.  This document explains the scope and purpose of a SAP network
   model and its relation with other models (Section 4).

   Multiple service types can be associated with a given network.
   Whether a SAP topology is dedicated to a specific service or shared
   among many services is deployment specific.  This document supports
   both deployment schemes.

   This document does not make any assumption about the service(s)
   provided by a network to its users.  VPN services (e.g., Layer 3
   Virtual Private Network (L3VPN) or Layer 2 Virtual Private Network
   (L2VPN)) [RFC4026] are used for illustration purposes (Appendices A
   and B).

   Given that User-Network Interface (UNI) and Network-to-Network
   Interface (NNI) are reference points that are widely used by
   operators to indicate the demarcation points when delivering
   services, both UNI and NNI SAPs are supported in the document.  The
   reader may refer, e.g., to [MEF6], [MEF17], [RFC6004], or [RFC6215]
   for a discussion on the use of UNI and NNI reference points.  An
   example of NNI usage in a VPN context is provided in Appendix C.

   The YANG data model in Section 6 conforms to the Network Management
   Datastore Architecture (NMDA) [RFC8342].

2.  Terminology

   This document assumes that the reader is familiar with the contents
   of [RFC6241], [RFC7950], [RFC8345], and [RFC8309].  The document uses
   terms from those documents.

   The meanings of the symbols in tree diagrams are defined in
   [RFC8340].



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   This document uses the term "network model" defined in Section 2.1 of
   [RFC8969].

   This document uses the following terms:

   Service povider:  The organization responsible for operating the
      network that offers a service (e.g., a VPN) to customers.

   Attachment Circuit (AC):  A channel that connects a Customer Edge
      (CE) to a Provider Edge (PE).  The AC may be a physical or logical
      link (Section 6.1 of [RFC4026]).

   Customer Edge (CE):  An equipment that is dedicated to a particular
      customer and is directly connected to one or more PEs via ACs.  A
      CE is usually located at the customer premises.  A CE may be
      dedicated to a single service (e.g., L3VPN), although it may
      support multiple VPNs if each one has separate attachment
      circuits.  A CE can be a router, a bridge, a switch, etc.

   Provider Edge (PE):  An equipment owned and managed by the service
      provider that can support multiple services (e.g., VPNs) for
      different customers.  A PE is directly connected to one or more
      CEs via ACs.

   Service Attachment Points (SAPs):  An abstraction of the network
      reference points (e.g., PE side of an AC) where network services
      can be delivered and/or being delivered to customers.

3.  SAP Network Model Usage

   Management operations of a service provider network can be automated
   using a variety of means such as interfaces based on YANG modules
   [RFC8969].  From that standpoint, and considering the architecture
   depicted in Figure 1, a goal of this document is to provide a
   mechanism to show via a YANG-based interface an abstracted network
   view from the network controller to the service orchestration layer
   with a focus on where a service can be delivered to customers.  The
   model is also used to retrieve the network reference points where a
   service is being delivered to customers.  For services that require
   resources from peer networks, the module can also be used to expose
   NNIs.










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                               +-----------------+
                               |     Customer    |
                               +--------+--------+
               Customer Service Models  |
                  (e.g., L3SM, L2SM)    |
                               +--------+--------+
                               |    Service      |
                               |  Orchestration  |
                               +------+---+------+
                   Network Models     |   | SAP Network Model
                 (e.g., L3NM, L2NM)   |   |
                               +------+---+------+
                               |     Network     |
                               |   Controller    |
                               +--------+--------+
                                        |
                  +---------------------+---------------------+
                  |                  Network                  |
                  +-------------------------------------------+

                     Figure 1: SAP Network Model Usage

   Let us consider the example of a typical service provider network
   (Figure 2), with PE and P nodes.

                     .---------.          .---------.
                     |   PE1   |          |   PE2   |
                     '---------'          '---------'
                                \        /
                                 .------.
                                 | P(s) |
                                 '------'
                               /         \
                     .---------.          .---------.
                     |   PE3   |          |   PE4   |
                     '---------'          '---------'

                     Figure 2: Sample Network Topology

   The service orchestration layer does not need to know about the
   internals of the underlying network (e.g., P nodes).  Figure 3 shows
   the abstract network view as seen by a service orchestrator.
   However, this view is not enough to provide to the service
   orchestration layer the information to create services in the
   network.  The service topology need is to be able to expose the set
   of nodes and the attachment points associated with the nodes from
   which network services can be grafted (delivered).




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                     .---------.          .---------.
                     |   PE1   |          |   PE2   |
                     '---------'          '---------'


                     .---------.          .---------.
                     |   PE3   |          |   PE4   |
                     '---------'          '---------'

                    Figure 3: Abstract Network Topology

   Typically, and focusing on the UNIs, the service orchestration layer
   would see a set of PEs and a set of client-facing interfaces
   (physical or logical) to which CEs can be connected (or are actually
   connected).  The service orchestration layer can use these interfaces
   to setup the requested services or to commit the delivery of a
   service.  Figure 4 depicts a sample SAP network topology that is
   maintained by the network controller and exposed to the service
   orchestration.

                 .-+-. .-+-. .-+-.              .-+-.       .-+-.
               .-|sap|-|sap|-|sap|-.          .-|sap|-------|sap|-.
               | '---' '---' '---' |          | '---'       '---' |
             .---.                 |          |                   |
             |sap|      PE1        |          |         PE2       |
             '---'                 |          |                   |
               |                   |          |                   |
               '-------------------'          '-------------------'


               .-------------------.          .-------------------.
               |                   |          |                   |
               |                   |          |                 .---.
               |         PE3       |          |        PE4      |sap|
               |                   |          |                 '---'
               | .---. .---. .---. |          | .---. .---. .---. |
               '-|sap|-|sap|-|sap|-'          '-|sap|-|sap|-|sap|-'
                 '-+-' '-+-' '-+-'              '-+-' '-+-' '-+-'

                       Figure 4: SAP Network Topology

   A single SAP network topology can be used for one or multiple service
   types (e.g., L3VPN, Ethernet VPN (EVPN)).  The network controller
   can, then, expose the service type(s) and associated interfaces via
   the SAPs.






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   As shown in Figure 5, the service orchestration layer will have also
   access to a set of customer service model (e.g., the L3SM or the
   L2SM) in the customer-facing interface and a set of network models
   (e.g., the L3NM and network topology data models) in the resource-
   facing interface.  In this use case, it is assumed that the network
   controller is unaware of what happens beyond the PEs towards the CEs;
   it is only responsible for the management and control of the SAPs and
   the network between PEs.  In order to correlate between delivery
   points expressed in service requests and SAPs, the SAP model may
   include a peer customer point identifier.  That identifier can be a
   CE identifier, a site identifier, etc.

                                                        .---.
                                                        |CE2|
                                                        '-+-'
                                                          |
             .-+-. .-+-. .-+-.              .-+-.       .-+-.
           .-|sap|-|sap|-|sap|-.          .-|sap|-------|sap|-.
           | '---' '---' '---' |          | '---'       '---' |
  .---.  .---.                 |          |                   |
  |CE1+--+sap|      PE1        |          |         PE2       |
  '---'  '---'                 |          |                   |
           |                   |          |                   |
           '-------------------'          '-------------------'


           .-------------------.          .-------------------.
           |                   |          |                   |
           |                   |          |                 .---.  .---.
           |         PE3       |          |        PE4      |sap+--+CE5|
           |                   |          |                 '---'  '---'
           | .---. .---. .---. |          | .---. .---. .---. |
           '-|sap|-|sap|-|sap|-'          '-|sap|-|sap|-|sap|-'
             '-+-' '-+-' '-+-'              '-+-' '-+-' '-+-'
                           |                  |     |
                         .-+-.                |   .-+-.
                         |CE3+----------------'   |CE4|
                         '-+-'                    '-+-'

               Figure 5: Network Topology with CEs and ACs

   Refer to Appendix A for an example echoing the topology depicted in
   Figure 5.








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4.  Relationship to Other YANG Data Models

   The SAP network model can be seen as inventory data associated with
   SAPs.  The model maintains an inventory of nodes contained in a
   network relying upon [RFC8345].

                              +-------------------------+
                              |                         |
                              |  Abstract Network Model |
                              |                         |
                              +------------+------------+
                                           |
                                 +---------+---------+
                                 |                   |
                          +------V------+     +------V------+
                          |  Abstract   |     |  Inventory  |
                          |  Network    |     |   Model(s)  |
                          |  Topology   |     |   e.g., SAP |
                          |   Model     |     |   Network   |
                          |             |     |    Model    |
                          +-----+-------+     +-------------+
                                |
                    +-----------+-----------+
                    |           |           |
               +----V----+ +----V----+ +----V----+
               |TE Topo  | |L3 Topo  | |L2 Topo  |
               |  Model  | |  Model  | |  Model  | ...
               +---------+ +---------+ +---------+

          Figure 6: Relation of SAP Network Model to Other Models

   Figure 6 depicts the relationship of the SAP network model to other
   models.  The SAP network model augments the Network model [RFC8345]
   and imports the Network Topology model, while other technology-
   specific topology models (e.g., Traffic Engineering (TE) Topologies
   model [RFC8795] or Layer 3 Topologies model [RFC8346]) augment the
   Network Topology model.

   Also, the SAP is not a tunnel termination point (TTP) (Section 3.6 of
   [RFC8795]) nor a link.

   In the context of Software-Defined Networking (SDN)
   [RFC7149][RFC7426], the SAP YANG data model can be used to exchange
   information between control elements, so as to support VPN service
   provision and resource management discussed in
   [RFC9182][I-D.ietf-opsawg-l2nm].  Through this data model, the
   service orchestration layer can learn the available endpoints (i.e.,
   SAPs) of interconnection resources of the underlying network.  The



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   service orchestration layer can determine which interconnection
   endpoints to add to an L2VPN or L3VPN service.  With the help of
   other data models (e.g., L3SM [RFC8299] or L2SM [RFC8466]),
   hierarchical control elements can also assess the feasibility of an
   end-to-end IP connectivity or L2VPN connectivity and, therefore,
   derive the sequence of domains and the points of interconnection to
   use.

   Advanced low-level interface-specific data nodes are not exposed in
   the SAP model.  Filters based on the interface identifiers listed in
   the SAP model can be used together with dedicated device models to
   set or get such data.

5.  SAP Module Tree Structure

   The SAP network model 'ietf-sap-ntw' builds on the 'ietf-network'
   module [RFC8345] by augmenting the nodes with SAPs.

   The structure of the 'ietf-sap-ntw' module is shown in Figure 7.

          module: ietf-sap-ntw
            augment /nw:networks/nw:network/nw:network-types:
              +--rw sap-network!
                 +--rw service-type*   identityref
            augment /nw:networks/nw:network/nw:node:
              +--rw service* [service-type]
                 +--rw service-type                   identityref
                 +--rw sap* [sap-id]
                    +--rw sap-id                      string
                    +--rw description?                string
                    +--rw parent-termination-point?   nt:tp-id
                    +--rw attachment-interface?       string
                    +--rw interface-type?             identityref
                    +--rw encapsulation-type?         identityref
                    +--rw role?                       identityref
                    +--rw peer-sap-id?                string
                    +--ro sap-status
                    |  +--ro status?        identityref
                    |  +--ro last-change?   yang:date-and-time
                    +--ro service-status
                       +--ro status?        identityref
                       +--ro last-change?   yang:date-and-time

                  Figure 7: SAP YANG Module Tree Structure







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   A SAP network topology can be used for one or multiple service types
   ('service-type').  Examples of supported service types are as
   follows:

   *  L3VPN [RFC4364],

   *  Virtual Private LAN Service (VPLS) [RFC4761][RFC4762],

   *  Virtual Private Wire Service (VPWS) [RFC8214],

   *  BGP MPLS-Based Ethernet VPN [RFC7432],

   *  VPWS in Ethernet VPN [RFC8214],

   *  Provider Backbone Bridging Combined with Ethernet VPN (PBB-EVPN)
      [RFC7623],

   *  VXLAN-based EVPN [RFC8365],

   *  Virtual Networks [RFC8453],

   *  Enhanced VPN (VPN+) [I-D.ietf-teas-enhanced-vpn],

   *  Network slice [I-D.ietf-teas-ietf-network-slices],

   *  SDWAN [I-D.ietf-bess-bgp-sdwan-usage], and

   *  Basic IP connectivity.

   These service types build on the types that are already defined in
   [RFC9181] and additional types that are defined in this document.
   Other service types can be defined in future YANG modules, if needed.

   Filters based on the service type can be used to access per-service
   SAP topology.  A example is depicted in Figure 11.

   A node in the topology can support one or multiple service types
   ('service-type') among those listed under the 'sap-network'
   container.  A list of SAPs are then bound to each service type that
   is supported by a given node.  Each SAP is characterized as follows:

   'sap-id':  Includes an identifier that uniquely identifies a SAP
      within a node.

      The same SAP may appear under distinct service types.  In such a
      case, the same identifier is used for these service types in
      association.




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      SAPs that are associated with the interfaces that are directly
      hosting services, interfaces that are ready to host per-service
      sub-interfaces (but not yet activated), or service that are
      already instantiated on sub-interfaces are listed as SAPs.

      For example, 'sap-id' may be the VPN network access identifier in
      Section 7.6 of [RFC9182].  An example to illustrate the use of
      this attribute during service creation is provided in Appendix D.

   'description':  Includes a textual description of the SAP.

   'parent-termination-point':  Includes a reference to the parent
      interface to which the SAP is bound (e.g., a physical port).

      This attribute is used, e.g., to associate an interface with its
      sub-interfaces as all these interfaces may be listed under the
      SAPs of a node.  It is also used to link a SAP with the physical
      topology.

      For example, this data node can be used to map the IETF Network
      Slice endpoints ([I-D.ietf-teas-ietf-network-slices]) to the
      service/tunnel/path endpoints in the underlay network.

   'attachment-interface':  Indicates a reference to the interface to
      which the SAP is bound.  The same interface may host multiple
      services.

      Whether the attachment identifier echoes the content of the
      attachment interface is deployment specific.

      For example, this reference may be any of the identifiers ('l2-
      termination-point', 'local-bridge-reference', 'bearer-reference',
      or 'lag-interface-id') defined in Section 7.6.1 of [RFC9182] or
      'l3-termination-point' defined in Section 7.6.2 of [RFC9182].  It
      is responsibility of the controller to ensure that consistent
      references are used in the SAP and underlying device modes or any
      other device inventory mechanism.

   'interface-type':  Indicates whether a SAP is bound to a physical
      port, a loopback interface, a Link Aggregation Group (LAG)
      interface [IEEE802.1AX], an Integrated Routing Bridge (IRB) (e.g.,
      [RFC9135]), a local bridge reference, etc.

      The mapping to the detailed interface types as per [RFC7224] is
      maintained by the controller.  That mapping is used, for example,
      when the controller translates this SAP network module into device
      modules.




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   'encapsulation-type':  Indicates the encapsulation type for the
      interface indicated in the 'attachment-interface' attribute.  The
      types are taken from [RFC9181].

      This data node can be used, for example, to decide whether an
      existing SAP can be (re)used to host a service or if a new sub-
      interface has to be instantiated.

   'role':  Specifies the role of a SAP (e.g., a UNI or NNI).

      A SAP inherits the role of its parent interface ('parent-
      termination-point').

   'peer-sap-id':  Includes a reference to the remote endpoint of an
      attachment circuit.

      Examples of such a reference are: a site identifier (Section 6.3
      of [RFC8299]), a Service Demarcation Point (SDP) identifier
      (Section 2.1 of [I-D.ietf-teas-ietf-network-slices]), the IP
      address of a peer Autonomous System Border Router (ASBR).

   'sap-status':  Indicates the operational status of a SAP.  Values are
      taken from the values defined in [RFC9181].

      When both a sub-interface and its parent interface are present,
      the status of the parent interface takes precedence over the
      status indicated for the sub-interface.

   'service-status':  Reports the operational status of service for a
      given SAP.  This information is particularly useful when many
      services are enabled for the same SAP, but only a subset of them
      are activated.


6.  SAP YANG Module

   This module imports types from [RFC8343], [RFC8345], and [RFC9181].

   The 'sap-information' is defined as a grouping for the reuse of these
   nodes in service-specific YANG modules.

   <CODE BEGINS> file "ietf-sap-ntw@2022-04-11.yang"
   module ietf-sap-ntw {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-sap-ntw";
     prefix sap;

     import ietf-network-topology {



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       prefix nt;
       reference
         "RFC 8345: A YANG Data Model for Network
                    Topologies, Section 6.2";
     }
     import ietf-network {
       prefix nw;
       reference
         "RFC 8345: A YANG Data Model for Network
                    Topologies, Section 6.1";
     }
     import ietf-vpn-common {
       prefix vpn-common;
       reference
         "RFC 9181: A Common YANG Data Model for Layer 2 and Layer 3
                    VPNs";
     }

     organization
       "IETF OPSA (Operations and Management Area) Working Group ";
     contact
       "WG Web:   <https://datatracker.ietf.org/wg/opsawg/>
        WG List:  <mailto:opsawg@ietf.org>

        Editor:   Mohamed Boucadair
                  <mailto:mohamed.boucadair@orange.com>

        Author:   Oscar Gonzalez de Dios
                  <mailto:oscar.gonzalezdedios@telefonica.com>

        Author:   Samier Barguil
                  <mailto:samier.barguilgiraldo.ext@telefonica.com>

        Author:   Qin Wu
                  <mailto:bill.wu@huawei.com>

        Author:   Victor Lopez
                  <victor.lopez@nokia.com>";
     description
       "This YANG module defines a model for representing, managing,
        and controlling the Service Attachment Points (SAPs) in the
        network topology.

        Copyright (c) 2022 IETF Trust and the persons identified as
        authors of the code.  All rights reserved.

        Redistribution and use in source and binary forms, with or
        without modification, is permitted pursuant to, and subject to



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        the license terms contained in, the Revised BSD License set
        forth in Section 4.c of the IETF Trust's Legal Provisions
        Relating to IETF Documents
        (https://trustee.ietf.org/license-info).

        This version of this YANG module is part of RFC XXXX
        (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself
        for full legal notices.";

     revision 2022-04-11 {
       description
         "Initial version";
       reference
         "RFC XXXX: A Network YANG Model for Service Attachment
                    Points (SAPs)";
     }

     identity virtual-network {
       base vpn-common:service-type;
       description
         "Virtual network. Refers to a logical network instance
          that is built over a physical network.";
       reference
         "RFC 8453: Framework for Abstraction and Control of TE
                    Networks (ACTN)";
     }

     identity enhanced-vpn {
       base vpn-common:service-type;
       description
         "Enhanced VPN (VPN+). VPN+ is an approach that is
          based on existing VPN and Traffic Engineering (TE)
          technologies but adds characteristics that specific
          services require over and above traditional VPNs.";
       reference
         "draft-ietf-teas-enhanced-vpn:
            A Framework for Enhanced Virtual Private Network
            (VPN+) Services";
     }

     identity network-slice {
       base vpn-common:service-type;
       description
         "IETF network slice.  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
          objectives.";



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       reference
         "draft-ietf-teas-ietf-network-slices:
            Framework for IETF Network Slices";
     }

     identity sdwan {
       base vpn-common:service-type;
       description
         "PE-based Software-Defined Wide Area Network (SDWAN).";
       reference
         "draft-ietf-bess-bgp-sdwan-usage: BGP Usage for SDWAN
            Overlay Network";
     }

     identity basic-connectivity {
       base vpn-common:service-type;
       description
         "Basic IP connectivity. This is, for example, a plain
          connectivity offered to Enterprises over a dedicated
          or shared MPLS infrastructure.";
     }

     identity interface-role {
       description
         "Base identity for the network role of an interface.";
     }

     identity uni {
       base interface-role;
       description
         "User-Network Interface (UNI).";
     }

     identity nni {
       base interface-role;
       description
         "Network-to-Network Interface (NNI).";
     }

     identity interface-type {
       description
         "Base identity for the interface type.";
     }

     identity phy {
       base interface-type;
       description
         "Physical port.";



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     }

     identity loopback {
       base interface-type;
       description
         "Loopback interface.";
     }

     identity lag {
       base interface-type;
       description
         "Link Aggregation Group (LAG) interface.";
     }

     identity irb {
       base interface-type;
       description
         "Integrated Routing Bridge (IRB). An IRB typically
          connects an IP-VRF to a bridge domain.";
     }

     identity local-bridge {
       base interface-type;
       description
         "A local bridge reference to accommodate, e.g.,
          implementations that require internal bridging.
          When such a type is used, a reference to a local
          bridge domain is used to identify the interface.";
     }

     identity logical {
       base interface-type;
       description
         "Refers to a logical sub-interface that is typically
          used to bind a service. This type is used only
          if none of the other logical types can be used.";
     }

     grouping sap-information {
       description
         "Service Attachment Point (SAP) information.";
       list sap {
         key "sap-id";
         description
           "The Service Attachment Points are abstraction of
            the points where network services such as L3VPNs,
            L2VPNs, or network slices can be attached to.";
         leaf sap-id {



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           type string;
           description
             "Indicates an identifier that uniquely identifies
              SAP within a node.";
         }
         leaf description {
           type string;
           description
             "A textual description of the SAP.";
         }
         leaf parent-termination-point {
           type nt:tp-id;
           description
             "Indicates the parent termination point to
              which the SAP is attached to. A termination
              point can be a physical port, an interface, etc.";
         }
         leaf attachment-interface {
           type string;
           description
             "Indicates the interface to which the SAP is bound.";
         }
         leaf interface-type {
           type identityref {
             base interface-type;
           }
           description
             "The type of the interface to which the SAP is bound.";
         }
         leaf encapsulation-type {
           type identityref {
             base vpn-common:encapsulation-type;
           }
           description
             "Encapsulation type of the interface to which the
              SAP is bound.";
         }
         leaf role {
           type identityref {
             base interface-role;
           }
           description
             "Indicates the role of a SAP.";
         }
         leaf peer-sap-id {
           type string;
           description
             "Indicates an identifier of the peer's termination



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              identifier (e.g., Customer Edge (CE)). This
              information can be used for correlation purposes,
              such as identifying the SAP that is attached to
              an endpoint that is provided in a service request.";
         }
         container sap-status {
           config "false";
           description
             "Indicates the SAP status.";
           uses vpn-common:oper-status-timestamp;
         }
         container service-status {
           config "false";
           description
             "Indicates the service status.";
           uses vpn-common:oper-status-timestamp;
         }
       }
     }

     augment "/nw:networks/nw:network/nw:network-types" {
       description
         "Introduces a new network type for SAP network.";
       container sap-network {
         presence "Indicates SAP network type.";
         description
           "The presence of the container node indicates the
            SAP network type.";
         leaf-list service-type {
           type identityref {
             base vpn-common:service-type;
           }
           description
             "Indicates the set of supported service types.";
         }
       }
     }

     augment "/nw:networks/nw:network/nw:node" {
       when "../nw:network-types/sap:sap-network" {
         description
           "Augmentation parameters apply only for SAP
            networks.";
       }
       description
         "SAP parameters for the node level.";
       list service {
         key "service-type";



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         description
           "A list of supported service types for the node.";
         leaf service-type {
           type identityref {
             base vpn-common:service-type;
           }
           description
             "Indicates a service type.";
         }
         uses sap-information;
      }
     }
   }
   <CODE ENDS>

7.  IANA Considerations

   This document registers the following namespace URI in the "ns"
   subregistry within the "IETF XML Registry" [RFC3688]:

       URI: urn:ietf:params:xml:ns:yang:ietf-sap-ntw
       Registrant Contact: The IESG.
       XML: N/A, the requested URI is an XML namespace.

   This document registers the following YANG module in the YANG Module
   Names registry [RFC6020] within the "YANG Parameters" registry:

       name: ietf-sap-ntw
       namespace: urn:ietf:params:xml:ns:yang:ietf-sap-ntw
       maintained by IANA? N
       prefix: sap
       reference: RFC XXXX

8.  Security Considerations

   The YANG module specified in this document defines schema for data
   that is designed to be accessed via network management protocols such
   as NETCONF [RFC6241] or RESTCONF [RFC8040].  The lowest NETCONF layer
   is the secure transport layer, and the mandatory-to-implement secure
   transport is Secure Shell (SSH) [RFC6242].  The lowest RESTCONF layer
   is HTTPS, and the mandatory-to-implement secure transport is TLS
   [RFC8446].

   The Network Configuration Access Control Model (NACM) [RFC8341]
   provides the means to restrict access for particular NETCONF or
   RESTCONF users to a preconfigured subset of all available NETCONF or
   RESTCONF protocol operations and content.




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   There are a number of data nodes defined in this YANG module that are
   writable/creatable/deletable (i.e., config true, which is the
   default).  These data nodes may be considered sensitive or vulnerable
   in some network environments.  Write operations (e.g., edit-config)
   to these data nodes without proper protection can have a negative
   effect on network operations.  These are the subtrees and data nodes
   and their sensitivity/vulnerability:

   *  /nw:networks/nw:network/nw:node/sap:service-type/sap:sap

      This subtree specifies the configurations of the nodes in a SAP
      network model.  Unexpected changes to this subtree (e.g.,
      associating a SAP with another parent termination interface) could
      lead to service disruption and/or network misbehavior.

   Some of the readable data nodes in this YANG module may be considered
   sensitive or vulnerable in some network environments.  It is thus
   important to control read access (e.g., via get, get-config, or
   notification) to these data nodes.  These are the subtrees and data
   nodes and their sensitivity/vulnerability:

   *  /nw:networks/nw:network/nw:node/sap:service-type/sap:sap

      Unauthorized access to this subtree can disclose the operational
      state information of the nodes in a SAP network model (e.g.,
      disclose the identity of a customer 'peer-sap-id').


9.  Acknowledgements

   Thanks to Adrian Farrell, Daniel King, Dhruv Dhody, Benoit Claise, Bo
   Wu, Erez Segev, Raul Arco, Joe Clarke, Riyas Valiyapalathingal, Tom
   Petch, and Olga Havel for the comments.

   Thanks to Martin Bjoerklund for yang-doctors review, Menachem Dodge
   for the opsdir review, and Mach Chen for the rtgdir review.

10.  References

10.1.  Normative References

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              DOI 10.17487/RFC3688, January 2004,
              <https://www.rfc-editor.org/info/rfc3688>.







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   [RFC6020]  Bjorklund, M., Ed., "YANG - A Data Modeling Language for
              the Network Configuration Protocol (NETCONF)", RFC 6020,
              DOI 10.17487/RFC6020, October 2010,
              <https://www.rfc-editor.org/info/rfc6020>.

   [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
              and A. Bierman, Ed., "Network Configuration Protocol
              (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
              <https://www.rfc-editor.org/info/rfc6241>.

   [RFC6242]  Wasserman, M., "Using the NETCONF Protocol over Secure
              Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
              <https://www.rfc-editor.org/info/rfc6242>.

   [RFC7950]  Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
              RFC 7950, DOI 10.17487/RFC7950, August 2016,
              <https://www.rfc-editor.org/info/rfc7950>.

   [RFC8040]  Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
              Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
              <https://www.rfc-editor.org/info/rfc8040>.

   [RFC8341]  Bierman, A. and M. Bjorklund, "Network Configuration
              Access Control Model", STD 91, RFC 8341,
              DOI 10.17487/RFC8341, March 2018,
              <https://www.rfc-editor.org/info/rfc8341>.

   [RFC8345]  Clemm, A., Medved, J., Varga, R., Bahadur, N.,
              Ananthakrishnan, H., and X. Liu, "A YANG Data Model for
              Network Topologies", RFC 8345, DOI 10.17487/RFC8345, March
              2018, <https://www.rfc-editor.org/info/rfc8345>.

   [RFC8346]  Clemm, A., Medved, J., Varga, R., Liu, X.,
              Ananthakrishnan, H., and N. Bahadur, "A YANG Data Model
              for Layer 3 Topologies", RFC 8346, DOI 10.17487/RFC8346,
              March 2018, <https://www.rfc-editor.org/info/rfc8346>.

   [RFC8446]  Rescorla, E., "The Transport Layer Security (TLS) Protocol
              Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
              <https://www.rfc-editor.org/info/rfc8446>.

   [RFC8795]  Liu, X., Bryskin, I., Beeram, V., Saad, T., Shah, H., and
              O. Gonzalez de Dios, "YANG Data Model for Traffic
              Engineering (TE) Topologies", RFC 8795,
              DOI 10.17487/RFC8795, August 2020,
              <https://www.rfc-editor.org/info/rfc8795>.





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   [RFC9181]  Barguil, S., Gonzalez de Dios, O., Ed., Boucadair, M.,
              Ed., and Q. Wu, "A Common YANG Data Model for Layer 2 and
              Layer 3 VPNs", RFC 9181, DOI 10.17487/RFC9181, February
              2022, <https://www.rfc-editor.org/info/rfc9181>.

10.2.  Informative References

   [I-D.ietf-bess-bgp-sdwan-usage]
              Dunbar, L., Guichard, J., Sajassi, A., Drake, J., Najem,
              B., and D. Carrel, "BGP Usage for SDWAN Overlay Networks",
              Work in Progress, Internet-Draft, draft-ietf-bess-bgp-
              sdwan-usage-05, 18 April 2022,
              <https://www.ietf.org/archive/id/draft-ietf-bess-bgp-
              sdwan-usage-05.txt>.

   [I-D.ietf-opsawg-l2nm]
              Boucadair, M., Dios, O. G. D., Barguil, S., and L. A.
              Munoz, "A YANG Network Data Model for Layer 2 VPNs", Work
              in Progress, Internet-Draft, draft-ietf-opsawg-l2nm-16, 13
              May 2022, <https://www.ietf.org/archive/id/draft-ietf-
              opsawg-l2nm-16.txt>.

   [I-D.ietf-teas-enhanced-vpn]
              Dong, J., Bryant, S., Li, Z., Miyasaka, T., and Y. Lee, "A
              Framework for Enhanced Virtual Private Network (VPN+)
              Services", Work in Progress, Internet-Draft, draft-ietf-
              teas-enhanced-vpn-10, 6 March 2022,
              <https://www.ietf.org/archive/id/draft-ietf-teas-enhanced-
              vpn-10.txt>.

   [I-D.ietf-teas-ietf-network-slices]
              Farrel, A., 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-10, 27 March 2022,
              <https://www.ietf.org/archive/id/draft-ietf-teas-ietf-
              network-slices-10.txt>.

   [IEEE802.1AX]
              "Link Aggregation", IEEE Std 802.1AX-2020, 2020.

   [MEF17]    Forum, T. M. E., "Technical Specification MEF 17, Service
              OAM Requirements & Framework – Phase 1", April 2007,
              <https://www.mef.net/wp-content/uploads/2015/04/MEF-
              17.pdf>.






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   [MEF6]     Forum, T. M. E., "Technical Specification MEF 6, Ethernet
              Services Definitions - Phase I", June 2004,
              <https://www.mef.net/Assets/Technical_Specifications/PDF/
              MEF_6.pdf>.

   [RFC4026]  Andersson, L. and T. Madsen, "Provider Provisioned Virtual
              Private Network (VPN) Terminology", RFC 4026,
              DOI 10.17487/RFC4026, March 2005,
              <https://www.rfc-editor.org/info/rfc4026>.

   [RFC4364]  Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
              Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February
              2006, <https://www.rfc-editor.org/info/rfc4364>.

   [RFC4761]  Kompella, K., Ed. and Y. Rekhter, Ed., "Virtual Private
              LAN Service (VPLS) Using BGP for Auto-Discovery and
              Signaling", RFC 4761, DOI 10.17487/RFC4761, January 2007,
              <https://www.rfc-editor.org/info/rfc4761>.

   [RFC4762]  Lasserre, M., Ed. and V. Kompella, Ed., "Virtual Private
              LAN Service (VPLS) Using Label Distribution Protocol (LDP)
              Signaling", RFC 4762, DOI 10.17487/RFC4762, January 2007,
              <https://www.rfc-editor.org/info/rfc4762>.

   [RFC6004]  Berger, L. and D. Fedyk, "Generalized MPLS (GMPLS) Support
              for Metro Ethernet Forum and G.8011 Ethernet Service
              Switching", RFC 6004, DOI 10.17487/RFC6004, October 2010,
              <https://www.rfc-editor.org/info/rfc6004>.

   [RFC6215]  Bocci, M., Levrau, L., and D. Frost, "MPLS Transport
              Profile User-to-Network and Network-to-Network
              Interfaces", RFC 6215, DOI 10.17487/RFC6215, April 2011,
              <https://www.rfc-editor.org/info/rfc6215>.

   [RFC7149]  Boucadair, M. and C. Jacquenet, "Software-Defined
              Networking: A Perspective from within a Service Provider
              Environment", RFC 7149, DOI 10.17487/RFC7149, March 2014,
              <https://www.rfc-editor.org/info/rfc7149>.

   [RFC7224]  Bjorklund, M., "IANA Interface Type YANG Module",
              RFC 7224, DOI 10.17487/RFC7224, May 2014,
              <https://www.rfc-editor.org/info/rfc7224>.

   [RFC7426]  Haleplidis, E., Ed., Pentikousis, K., Ed., Denazis, S.,
              Hadi Salim, J., Meyer, D., and O. Koufopavlou, "Software-
              Defined Networking (SDN): Layers and Architecture
              Terminology", RFC 7426, DOI 10.17487/RFC7426, January
              2015, <https://www.rfc-editor.org/info/rfc7426>.



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   [RFC7432]  Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A.,
              Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based
              Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432, February
              2015, <https://www.rfc-editor.org/info/rfc7432>.

   [RFC7623]  Sajassi, A., Ed., Salam, S., Bitar, N., Isaac, A., and W.
              Henderickx, "Provider Backbone Bridging Combined with
              Ethernet VPN (PBB-EVPN)", RFC 7623, DOI 10.17487/RFC7623,
              September 2015, <https://www.rfc-editor.org/info/rfc7623>.

   [RFC8214]  Boutros, S., Sajassi, A., Salam, S., Drake, J., and J.
              Rabadan, "Virtual Private Wire Service Support in Ethernet
              VPN", RFC 8214, DOI 10.17487/RFC8214, August 2017,
              <https://www.rfc-editor.org/info/rfc8214>.

   [RFC8299]  Wu, Q., Ed., Litkowski, S., Tomotaki, L., and K. Ogaki,
              "YANG Data Model for L3VPN Service Delivery", RFC 8299,
              DOI 10.17487/RFC8299, January 2018,
              <https://www.rfc-editor.org/info/rfc8299>.

   [RFC8309]  Wu, Q., Liu, W., and A. Farrel, "Service Models
              Explained", RFC 8309, DOI 10.17487/RFC8309, January 2018,
              <https://www.rfc-editor.org/info/rfc8309>.

   [RFC8340]  Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
              BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
              <https://www.rfc-editor.org/info/rfc8340>.

   [RFC8342]  Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
              and R. Wilton, "Network Management Datastore Architecture
              (NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018,
              <https://www.rfc-editor.org/info/rfc8342>.

   [RFC8343]  Bjorklund, M., "A YANG Data Model for Interface
              Management", RFC 8343, DOI 10.17487/RFC8343, March 2018,
              <https://www.rfc-editor.org/info/rfc8343>.

   [RFC8365]  Sajassi, A., Ed., Drake, J., Ed., Bitar, N., Shekhar, R.,
              Uttaro, J., and W. Henderickx, "A Network Virtualization
              Overlay Solution Using Ethernet VPN (EVPN)", RFC 8365,
              DOI 10.17487/RFC8365, March 2018,
              <https://www.rfc-editor.org/info/rfc8365>.

   [RFC8453]  Ceccarelli, D., Ed. and Y. Lee, Ed., "Framework for
              Abstraction and Control of TE Networks (ACTN)", RFC 8453,
              DOI 10.17487/RFC8453, August 2018,
              <https://www.rfc-editor.org/info/rfc8453>.




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   [RFC8466]  Wen, B., Fioccola, G., Ed., Xie, C., and L. Jalil, "A YANG
              Data Model for Layer 2 Virtual Private Network (L2VPN)
              Service Delivery", RFC 8466, DOI 10.17487/RFC8466, October
              2018, <https://www.rfc-editor.org/info/rfc8466>.

   [RFC8969]  Wu, Q., Ed., Boucadair, M., Ed., Lopez, D., Xie, C., and
              L. Geng, "A Framework for Automating Service and Network
              Management with YANG", RFC 8969, DOI 10.17487/RFC8969,
              January 2021, <https://www.rfc-editor.org/info/rfc8969>.

   [RFC9135]  Sajassi, A., Salam, S., Thoria, S., Drake, J., and J.
              Rabadan, "Integrated Routing and Bridging in Ethernet VPN
              (EVPN)", RFC 9135, DOI 10.17487/RFC9135, October 2021,
              <https://www.rfc-editor.org/info/rfc9135>.

   [RFC9182]  Barguil, S., Gonzalez de Dios, O., Ed., Boucadair, M.,
              Ed., Munoz, L., and A. Aguado, "A YANG Network Data Model
              for Layer 3 VPNs", RFC 9182, DOI 10.17487/RFC9182,
              February 2022, <https://www.rfc-editor.org/info/rfc9182>.

Appendix A.  A Simplified SAP Network Example

   An example of a SAP topology that is reported by a network controller
   is depicted in Figure 8.  This example echoes the topology shown in
   Figure 5.  Only a minimum set of information is provided for each
   SAP.

   {
     "ietf-network:networks": {
       "network": [
         {
           "network-types": {
             "ietf-sap-ntw:sap-network": {
               "service-type": [
                 "ietf-vpn-common:l3vpn",
                 "ietf-vpn-common:vpls"
               ]
             }
           },
           "network-id": "foo:an-id",
           "node": [
             {
               "node-id": "foo:pe1",
               "ietf-sap-ntw:service": [
                 {
                   "service-type": "ietf-vpn-common:l3vpn",
                   "sap": [
                     {



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                       "sap-id": "sap#11",
                       "peer-sap-id": "ce-1",
                       "service-status": {
                         "status": "ietf-vpn-common:op-up"
                       }
                     },
                     {
                       "sap-id": "sap#12"
                     },
                     {
                       "sap-id": "sap#13"
                     },
                     {
                       "sap-id": "sap#14"
                     }
                   ]
                 }
               ]
             },
             {
               "node-id": "foo:pe2",
               "ietf-sap-ntw:service": [
                 {
                   "service-type": "ietf-vpn-common:l3vpn",
                   "sap": [
                     {
                       "sap-id": "sap#21"
                     },
                     {
                       "sap-id": "sap#22",
                       "peer-sap-id": "ce-2",
                       "service-status": {
                         "status": "ietf-vpn-common:op-up"
                       }
                     }
                   ]
                 }
               ]
             },
             {
               "node-id": "foo:pe3",
               "ietf-sap-ntw:service": [
                 {
                   "service-type": "ietf-vpn-common:l3vpn",
                   "sap": [
                     {
                       "sap-id": "sap#31"
                     },



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                     {
                       "sap-id": "sap#32"
                     },
                     {
                       "sap-id": "sap#33",
                       "peer-sap-id": "ce-3",
                       "service-status": {
                         "status": "ietf-vpn-common:op-up"
                       }
                     }
                   ]
                 }
               ]
             },
             {
               "node-id": "foo:pe4",
               "ietf-sap-ntw:service": [
                 {
                   "service-type": "ietf-vpn-common:l3vpn",
                   "sap": [
                     {
                       "sap-id": "sap#41",
                       "peer-sap-id": "ce-3",
                       "service-status": {
                         "status": "ietf-vpn-common:op-up"
                       }
                     },
                     {
                       "sap-id": "sap#42",
                       "peer-sap-id": "ce-4",
                       "service-status": {
                         "status": "ietf-vpn-common:op-up"
                       }
                     },
                     {
                       "sap-id": "sap#43"
                     },
                     {
                       "sap-id": "sap#44",
                       "peer-sap-id": "ce-5",
                       "service-status": {
                         "status": "ietf-vpn-common:op-up"
                       }
                     }
                   ]
                 }
               ]
             }



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           ]
         }
       ]
     }
   }

                 Figure 8: A Simplified SAP Network Example


Appendix B.  A Simple Example of SAP Network Model: Node Filter

   In the example shown in Figure 9, PE1 (with a "node-id" set to
   "foo:pe1") has two physical interfaces "GE0/6/1" and "GE0/6/4".  Two
   sub-interfaces "GE0/6/4.1" and "GE0/6/4.2" are associated with the
   physical interface "GE0/6/4".  Let us consider that four SAPs are
   exposed to the service orchestrator and mapped to these physical
   interfaces and sub-interfaces.

                  .-------------------------.
                  |                 GE0/6/4 |
                  | PE1                .----+----.
                  |                    |sap#2    |GE0/6/4.1
                  |                    |      .--+--.
                  |                    |      |sap#3|
                  |                    |      '--+--'
                  |                    |         |GE0/6/4.2
                  |                    |      .--+--.
                  |                    |      |sap#4|
                  |                    |      '--+--'
                  |                    |         |
                  |                    +----+----+
                  |                         |
                  |                  GE0/6/1|
                  |                    .----+----.
                  |                    |sap#1    |
                  |                    '----+----'
                  |                         |
                  '-------------------------'

      Figure 9: An Example of a PE and its Physical/Logical Interfaces

   Let us assume that no service is enabled yet for the SAP associated
   with the physical interface "GE0/6/1".  Also, let us assume that, for
   the SAPs that are associated with the physical interface "GE0/6/4",
   VPLS and L3VPN services are activated on the two sub-interfaces
   "GE0/6/4.1" and "GE0/6/4.2", respectively.





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   A service orchestrator can query what services are provided on which
   SAPs of PE1 from the network controller by sending, e.g., a GET
   RESTCONF request.  Figure 10 shows the body of the RESTCONF response
   that is received from the network controller.

   {
     "ietf-sap-ntw:service": [
       {
         "service-type": "ietf-vpn-common:l3vpn",
         "sap": [
           {
             "sap-id": "sap#1",
             "description": "Ready to host SAPs",
             "attachment-interface": "GE0/6/1",
             "interface-type": "ietf-sap-ntw:phy",
             "role": "ietf-sap-ntw:uni",
             "sap-status": {
               "status": "ietf-vpn-common:op-up"
             }
           },
           {
             "sap-id": "sap#2",
             "description": "Ready to host SAPs",
             "attachment-interface": "GE0/6/4",
             "interface-type": "ietf-sap-ntw:phy",
             "role": "ietf-sap-ntw:uni",
             "sap-status": {
               "status": "ietf-vpn-common:op-up"
             }
           },
           {
             "sap-id": "sap#3",
             "description": "A first SAP description",
             "parent-termination-point": "GE0/6/4",
             "attachment-interface": "GE0/6/4.1",
             "interface-type": "ietf-sap-ntw:logical",
             "encapsulation-type": "ietf-vpn-common:vlan-type",
             "sap-status": {
               "status": "ietf-vpn-common:op-up"
             },
             "service-status": {
               "status": "ietf-vpn-common:op-up"
             }
           }
         ]
       },
       {
         "service-type": "ietf-vpn-common:vpls",



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         "sap": [
             "sap-id": "sap#1",
             "description": "Ready to host SAPs",
             "attachment-interface": "GE0/6/1",
             "interface-type": "ietf-sap-ntw:phy",
             "role": "ietf-sap-ntw:uni",
             "sap-status": {
               "status": "ietf-vpn-common:op-up"
             }
           },
           {
             "sap-id": "sap#2",
             "description": "Ready to host SAPs",
             "attachment-interface": "GE0/6/4",
             "interface-type": "ietf-sap-ntw:phy",
             "role": "ietf-sap-ntw:uni",
             "sap-status": {
               "status": "ietf-vpn-common:op-up"
             }
           },
           {
             "sap-id": "sap#4",
             "description": "Another description",
             "parent-termination-point": "GE0/6/4",
             "attachment-interface": "GE0/6/4.2",
             "interface-type": "ietf-sap-ntw:logical",
             "encapsulation-type": "ietf-vpn-common:vlan-type",
             "sap-status": {
               "status": "ietf-vpn-common:op-up"
             },
             "service-status": {
               "status": "ietf-vpn-common:op-up"
             }
           }
         ]
       }
     ]
   }

     Figure 10: An Example of a Response Body to a Request with a Node
                                   Filter

   Figure 11 shows the message body of a response that is received from
   the network controller if the request includes a filter on the
   service type for a particular node:






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   {
     "ietf-sap-ntw:service": [
       {
         "service-type": "ietf-vpn-common:l3vpn",
         "sap": [
           {
             "sap-id": "sap#1",
             "description": "Ready to host SAPs",
             "attachment-interface": "GE0/6/1",
             "interface-type": "ietf-sap-ntw:phy",
             "role": "ietf-sap-ntw:uni",
             "sap-status": {
               "status": "ietf-vpn-common:op-up"
             }
           },
           {
             "sap-id": "sap#2",
             "description": "Ready to host SAPs",
             "attachment-interface": "GE0/6/4",
             "interface-type": "ietf-sap-ntw:phy",
             "role": "ietf-sap-ntw:uni",
             "sap-status": {
               "status": "ietf-vpn-common:op-up"
             }
           },
           {
             "sap-id": "sap#3",
             "description": "A first SAP description",
             "parent-termination-point": "GE0/6/4",
             "attachment-interface": "GE0/6/4.1",
             "interface-type": "ietf-sap-ntw:logical",
             "encapsulation-type": "ietf-vpn-common:vlan-type",
             "sap-status": {
               "status": "ietf-vpn-common:op-up"
             },
             "service-status": {
               "status": "ietf-vpn-common:op-up"
             }
           }
         ]
       }
     ]
   }

        Figure 11: An Example of a Response Body to a Request with a
                               Service Filter





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Appendix C.  An Example of NNI SAP: Inter-AS VPN Option A

   Section 10 of [RFC4364] discuses several options to extend a VPN
   service beyond the scope of a single Autonomous System (AS).  For
   illustration purposes, this section focuses on the so called "Option
   A" but similar examples can be considered for other options.

   In this option, an ASBR of an AS is directly connected to an ASBR of
   a neighboring AS.  These two ASBRs are connected by multiple physical
   or logical interfaces.  Also, at least one sub-interface is
   maintained by these ASBRs for each of the VPNs that require their
   routes to be passed from one AS to the other AS.  Each ASBR behaves
   as a PE and treats the other as if it were a CE.

   Figure 12 shows a simplified (excerpt) topology of two ASes A and B
   with a focus on the interconnection links between these two ASes.

    .--------------------.                      .--------------------.
    |                    |                      |                    |
    |              A  .--+--.                .--+--.  A              |
    |              S  |     +================+     |  S              |
    |              B  | (VRF1)----(VPN1)----(VRF1) |  B              |
    |              R  |     |                |     |  R              |
    |                 | (VRF2)----(VPN2)----(VRF2) |                 |
    |              a  |     +================+     |  b              |
    |              1  '--+--'                '--+--'  1              |
    |     AS A           |                      |         AS B       |
    |              A  .--+--.                .--+--.  A              |
    |              S  |     +================+     |  S              |
    |              B  | (VRF1)----(VPN1)----(VRF1) |  B              |
    |              R  |     |                |     |  R              |
    |                 | (VRF2)----(VPN2)----(VRF2) |                 |
    |              a  |     +================+     |  b              |
    |              2  '--+--'                '--+--'  2              |
    |                    |                      |                    |
    '--------------------'                      '--------------------'

              Figure 12: An Example of Inter-AS VPN (Option A)

   Figure 13 shows an example of a message body that is received from
   the network controller of AS A (with a focus on the NNIs shown in
   Figure 12).









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   {
     "ietf-network:networks": {
       "network": [
         {
           "network-types": {
             "ietf-sap-ntw:sap-network": {
               "service-type": [
                 "ietf-vpn-common:l3vpn"
               ]
             }
           },
           "network-id": "foo:an-id",
           "node": [
             {
               "node-id": "foo:asbr-a1",
               "ietf-sap-ntw:service": [
                 {
                   "service-type": "ietf-vpn-common:l3vpn",
                   "sap": [
                     {
                       "sap-id": "sap#11",
                       "description": "parent inter-as link#1",
                       "role": "ietf-sap-ntw:nni",
                       "peer-sap-id": "asbr-b1",
                       "service-status": {
                         "status": "ietf-vpn-common:op-up"
                       }
                     },
                     {
                       "sap-id": "sap#12",
                       "description": "parent inter-as link#2",
                       "role": "ietf-sap-ntw:nni",
                       "peer-sap-id": "asbr-b1",
                       "service-status": {
                         "status": "ietf-vpn-common:op-up"
                       }
                     },
                     {
                       "sap-id": "sap#13",
                       "description": "vpn1",
                       "role": "ietf-sap-ntw:nni",
                       "peer-sap-id": "asbr-b1",
                       "service-status": {
                         "status": "ietf-vpn-common:op-up"
                       }
                     },
                     {
                       "sap-id": "sap#14",



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                       "description": "vpn2",
                       "role": "ietf-sap-ntw:nni",
                       "peer-sap-id": "asbr-b1",
                       "service-status": {
                         "status": "ietf-vpn-common:op-up"
                       }
                     }
                   ]
                 }
               ]
             },
             {
               "node-id": "foo:asbr-a2",
               "ietf-sap-ntw:service": [
                 {
                   "service-type": "ietf-vpn-common:l3vpn",
                   "sap": [
                     {
                       "sap-id": "sap#11",
                       "description": "parent inter-as link#1",
                       "role": "ietf-sap-ntw:nni",
                       "peer-sap-id": "asbr-b2",
                       "service-status": {
                         "status": "ietf-vpn-common:op-up"
                       }
                     },
                     {
                       "sap-id": "sap#12",
                       "description": "parent inter-as link#2",
                       "role": "ietf-sap-ntw:nni",
                       "peer-sap-id": "asbr-b2",
                       "service-status": {
                         "status": "ietf-vpn-common:op-up"
                       }
                     },
                     {
                       "sap-id": "sap#21",
                       "description": "vpn1",
                       "role": "ietf-sap-ntw:nni",
                       "peer-sap-id": "asbr-b2",
                       "service-status": {
                         "status": "ietf-vpn-common:op-up"
                       }
                     },
                     {
                       "sap-id": "sap#22",
                       "description": "vpn2",
                       "role": "ietf-sap-ntw:nni",



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                       "peer-sap-id": "asbr-b2",
                       "service-status": {
                         "status": "ietf-vpn-common:op-up"
                       }
                     }
                   ]
                 }
               ]
             }
           ]
         }
       ]
     }
   }

                 Figure 13: An Example of SAP Usage for NNI


Appendix D.  An Example of Using the SAP Network Model in Service
             Creation

   This section describes an example to illustrate the use of the SAP
   model for service creation purposes.

   An example of a SAP topology is presented in Figure 8.  This example
   includes four PEs with their SAPs, as well as the customer
   information.

   Let us assume that an operator wants to create an L3VPN service
   between two PEs (PE3 and PE4) that are servicing two CEs (CE6 and
   CE7).  To that aim, the operator would query the SAP topology and
   would obtain a response similar to what is depicted in Figure 8.
   That response indicates that the SAPs having "sap#31" and "sap#43" as
   attachment identifiers do not have any installed services.  Once the
   "free" SAPs are identified, the 'interface-type' and 'encapsulation-
   type' are checked to see if the requested L3VPN service is compatible
   with the SAP characteristics.  If they are compatible, as proposed in
   Section 5, the 'attachment-id' value can be used as the VPN network
   access identifier in an L3NM create query.

   Let us now assume that, instead of the L3VPN service, the operator
   wants to set up an L2VPN service.  If the 'interface-type' is a
   physical port, a new logical SAP can be created using the SAP model
   to cope with the service needs (e.g., the 'encapsulation-type'
   attribute can be set to 'ietf-vpn-common:vlan-type').  Once the
   logical SAP is created, the 'attachment-id' of the new SAP is used to
   create an L2NM instance (Section 7.6 of [I-D.ietf-opsawg-l2nm]).




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Authors' Addresses

   Mohamed Boucadair (editor)
   Orange
   France
   Email: mohamed.boucadair@orange.com


   Oscar Gonzalez de Dios
   Telefonica
   Madrid
   Spain
   Email: oscar.gonzalezdedios@telefonica.com


   Samier Barguil
   Telefonica
   Madrid
   Spain
   Email: samier.barguilgiraldo.ext@telefonica.com


   Qin Wu
   Huawei
   101 Software Avenue, Yuhua District
   Nanjing
   Jiangsu, 210012
   China
   Email: bill.wu@huawei.com


   Victor Lopez
   Nokia
   Spain
   Email: victor.lopez@nokia.com
















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