A Network YANG Model for Service Attachment Points
draft-dbwb-opsawg-sap-00

Document Type Active Internet-Draft (individual)
Authors Oscar de Dios  , samier barguil  , Qin Wu  , Mohamed Boucadair  , Victor Lopez 
Last updated 2021-10-22
Replaces draft-ogondio-opsawg-uni-topology
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OPSAWG                                               O. Gonzalez de Dios
Internet-Draft                                                S. Barguil
Intended status: Standards Track                              Telefonica
Expires: 25 April 2022                                             Q. Wu
                                                                  Huawei
                                                            M. Boucadair
                                                                  Orange
                                                                V. Lopez
                                                                   Nokia
                                                         22 October 2021

           A Network YANG Model for Service Attachment Points
                        draft-dbwb-opsawg-sap-00

Abstract

   This document defines a YANG data model for representing an abstract
   view of the provider network topology containing the points from
   which its services can be attached (e.g., basic connectivity, VPN,
   network slices).  The data model augments the 'ietf-network' data
   model by adding the concept of service attachment points (SAPs).  The
   service attachment points are the points to which network services
   (such as L3VPN or L2VPN) can be attached.  The customer endpoint of
   an attachment circuits are not covered in the SAP network topology.

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 25 April 2022.

Copyright Notice

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

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   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 Simplified BSD License text
   as described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  SAP Network Model Usage . . . . . . . . . . . . . . . . . . .   4
   4.  SAP Module Tree Structure . . . . . . . . . . . . . . . . . .   7
   5.  Relation with other Models  . . . . . . . . . . . . . . . . .   9
   6.  SAP YANG Module . . . . . . . . . . . . . . . . . . . . . . .   9
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  15
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  15
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  16
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  16
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  16
     10.2.  Informative References . . . . . . . . . . . . . . . . .  18
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  20

1.  Introduction

   The service attachment point (SAP) is an important architectural
   concept in many implementations and deployments of services such as
   VPNs, SDWAN, or managed VoIP services.  It has already been used to
   decide where to attach and, thus, deliver the service in the L3SM
   [RFC8299] and the L2SM [RFC8466].

   This document defines a YANG network model for representing,
   managing, and controlling the service attachment points (SAPs).  The
   data model augments the 'ietf-network' module [RFC8345] by adding the
   concept of service attachment points.  The service attachment points
   are abstraction of the points where network services such as L3VPNs
   or L2VPNs can be attached.

   This document does not make any assumption about the service provided
   by the network to the users.  VPN services are used for illustration
   purposes.  This concept can also be used to decide network slice SAPs
   [I-D.ietf-teas-ietf-network-slices].

   In the context of Software-Defined Networking (SDN)
   [RFC7149][RFC7426], the defined YANG data model in this document can
   be used to exchange information between control elements, so as to

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   support VPN service provision and resource management discussed in
   [I-D.ietf-opsawg-l3sm-l3nm][I-D.ietf-opsawg-l2nm].  Through this data
   model, the service orchestration layer can learn the available
   endpoints (i.e., SAPs) of interconnection resource of the underlying
   network.

   The service orchestration layer can determine which endpoint of
   interconnection to add to L2VPN or L3VPN service.  With the help of
   other data models (e.g., L3SM [RFC8299] or L2SM [RFC8466]),
   hierarchical control elements could determine 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.

   This document explains the scope and purpose of a SAP network model
   and its relation with the service models and describes how it can be
   used by a network operator.  The document also shows how the topology
   and service models fit together.

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

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

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

   Tree diagrams used in this document follow the notation defined in
   [RFC8340].

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

   This document uses the following terms:

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

   Customer Edge (CE):  An equipment that is dedicated to a particular
      customer and is directly connected to one or more Provider Edges
      (PEs) via attachment circuits (ACs).  A CE is usually located at
      the customer premises.  A CE may be dedicated to a single service

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      (e.g., L3VPN), although it may support multiple VPNs if each one
      has separate attachment circuits.  A CE can be a router, bridge,
      switch, etc.

   Provider Edge (PE):  An equipment owned and managed by the SP that
      can support multiple services (e.g., VPNs) for different
      customers.  A PE is directly connected to one or more CEs via
      attachment circuits.  A PE is usually located at an SP point of
      presence (PoP).

   Attachment point (AP):  Describes a service's end point
      characteristics and its reference to a Termination Point (TP) of
      the PE; used as service access point for service.

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, the 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.

                               +-----------------+
                               |     Customer    |
                               +--------+--------+
               Customer Service Models  |
                                        |
                               +--------+--------+
                               |    Service      |
                               |  Orchestration  |
                               +------+---+------+
               Service Network Models |   | SAP Network Model
                                      |   |
                               +------+---+------+
                               |     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.

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                      +---------+         +---------+
                      |   PE1   |         |   PE2   |
                      +---------+         +---------+
                                 \       /
                                 +------+
                                 |  P   |
                                 +------+
                                /        \
                      +---------+         +---------+
                      |   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 the 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).

                      +---------+         +---------+
                      |   PE1   |         |   PE2   |
                      +---------+         +---------+

                      +---------+         +---------+
                      |   PE3   |         |   PE4   |
                      +---------+         +---------+

                    Figure 3: Abstract Network Topology

   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 them to setup the requested services or to commit the
   delivery of a service.  Figure 4 depicts the SAP network topology
   that is maintained by the network controller and exposed to the
   Service Orchestration.

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                 .---. .---. .---.              .---.       .---.
               +-|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 of multiple service
   types (e.g., L3VPN, EVPN).  The network controller can then expose
   the service type(s) and associated interfaces via the SAPs.

   As shown in Figure 5, the Service Orchestration layer will have also
   access to a set of Customer Service Model, e.g., an L3SM or L2SM data
   model in the customer-facing interface and a set of network models,
   e.g., 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 network
   between PEs.

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                                                        .---.
                                                        |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

4.  SAP Module Tree Structure

   The SAP network model builds on the network data model defined in the
   'ietf-network' module [RFC8345], augmenting the nodes with service
   attachment points, which anchor the links and are contained in nodes.
   The 'service-attachment-point' attribute defined in the SAP network
   model is not a tunnel termination point (TTP) nor a link, but an
   abstraction of the termination point defined in [RFC8345].

   The structure of the 'ietf-sap-ntw' module is shown in Figure 6.

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   module: ietf-sap-ntw
     augment /nw:networks/nw:network/nw:network-types:
       +--rw sap-network!
          +--rw sap-type*   identityref
     augment /nw:networks/nw:network/nw:node:
       +--rw service-attachment-point* [attachment-id]
          +--rw attachment-id          nt:tp-id
          +--ro interface-type?        identityref
          +--rw admin-status?          boolean
          +--rw oper-status?           boolean
          +--rw encapsulation-type?    identityref
          +--rw sap-type*              identityref
          +--rw service-description?   string

                      Figure 6: YANG Module Structure

   A SAP network topology can be used for one single service type or
   multiple types ("sap-type").  When a SAP topology is used for many
   service types, the underlying nodes must support at least one of
   these service types.  Examples of supported service types are listed
   below:

   *  L3VPN,

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

   *  VPLS using Label Distribution Protocol (LDP) [RFC4762],

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

   *  BGP MPLS-Based Ethernet VPN [RFC7432],

   *  Ethernet VPN (EVPN) [RFC8365],

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

   *  Virtual Networks [RFC8453],

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

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

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   A service attachment point is identified by an interface name
   ("attachment-id"), an interface type ("type"), a status ("admin-
   status", and "oper-status"), an encapsulation type ("encapsulation-
   type"), one or a list of service types ("sap-type") such as L3VPN or
   network slice, a description of the service(s) ("service-
   description").

5.  Relation with other Models

   The SAP network model can be seen as an inventory data associated
   with service attachment points.  The model maintains an inventory of
   nodes contained in a network based on [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 7: Relation of SAP Network Model to Other Models

   Figure 7 depicts the relationship of the SAP network model to other
   models.  The SAP network model augments from the Network model
   [RFC8345] and imports Network Topology model, while other technology-
   specific topology models (e.g., TE Topologies model [RFC8795] or L3
   Topology model [RFC8346]) augment from the Network Topology.

6.  SAP YANG Module

   This module imports types from [RFC8343], [RFC8345], and
   [I-D.ietf-opsawg-vpn-common].

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   <CODE BEGINS> file "ietf-sap-ntw@2021-10-16.yang"
   module ietf-sap-ntw {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-sap-ntw";
     prefix sap;

     import ietf-interfaces {
       prefix if;
       reference
         "RFC 8343: A YANG Data Model for Interface Management";
     }
     import ietf-network-topology {
       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 UUUU: A Layer 2/3 VPN Common YANG Model";
     }

     organization
       "IETF OPSA (Operations and Management Area) Working Group ";
     contact
       "Editor:   Oscar Gonzalez de Dios
                  <mailto:oscar.gonzalezdedios@telefonica.com>
        Editor:   Samier Barguil
                  <mailto:samier.barguilgiraldo.ext@telefonica.com>
        Editor:   Qin Wu
                  <mailto:bill.wu@huawei.com>
        Editor:   Mohamed Boucadair
                  <mailto:mohamed.boucadair@orange.com>";
     description
       "This YANG module defines a model for representing, managing,
        and controlling the Service Attachment Points (SAPs) in the
        network topology.

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

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        Redistribution and use in source and binary forms, with or
        without modification, is permitted pursuant to, and subject to
        the license terms contained in, the Simplified 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 2021-10-16 {
       description
         "Initial version";
       reference
         "RFC XXXX: A Network YANG Model for Service Attachment
                    Point (SAP)";
     }

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

     identity l3vpn {
       base service-type;
       description
         "L3VPN service.";
       reference
         "RFC 4364: BGP/MPLS IP Virtual Private Networks (VPNs)";
     }

     identity enhanced-vpn {
       base 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
         "I-D.ietf-teas-enhanced-vpn:
            A Framework for Enhanced Virtual Private Network
            (VPN+) Services";
     }

     identity network-slice {
       base service-type;
       description

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         "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.";
       reference
         "I-D.ietf-teas-ietf-network-slices:
            Framework for IETF Network Slices";
     }

     identity vpls {
       base service-type;
       description
         "VPLS service.";
       reference
         "RFC 4761: Virtual Private LAN Service (VPLS) Using BGP for
                    Auto-Discovery and Signaling
          RFC 4762: Virtual Private LAN Service (VPLS) Using Label
                    Distribution Protocol (LDP) Signaling";
     }

     identity vpws {
       base service-type;
       description
         "Virtual Private Wire Service (VPWS) service.";
       reference
         "RFC 4664: Framework for Layer 2 Virtual Private Networks
                    (L2VPNs), Section 3.1.1";
     }

     identity vpws-evpn {
       base service-type;
       description
         "EVPN used to support VPWS service.";
       reference
         "RFC 8214: Virtual Private Wire Service Support in Ethernet VPN";
     }

     identity pbb-evpn {
       base service-type;
       description
         "Provider Backbone Bridging (PBB) EVPNs service.";
       reference
         "RFC 7623: Provider Backbone Bridging Combined with Ethernet VPN
                    (PBB-EVPN)";
     }

     identity mpls-evpn {

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       base service-type;
       description
         "MPLS-based EVPN service.";
       reference
         "RFC 7432: BGP MPLS-Based Ethernet VPN";
     }

     identity vxlan-evpn {
       base service-type;
       description
         "VXLAN-based EVPN service.";
       reference
         "RFC 8365: A Network Virtualization Overlay Solution Using
                    Ethernet VPN (EVPN)";
     }

     identity virtual-network {
       base service-type;
       description
         "Virtual network.";
       reference
         "RFC 8453: Framework for Abstraction and Control of TE
                    Networks (ACTN)";
     }

     /*
      Other network service types may be added.
      */

     grouping sap-information {
       description
         "Service Attachment Point (SAP) information.";
       list service-attachment-point {
         key "attachment-id";
         description
           "The service attachment points are abstraction of
            the points where network services such as L3VPNs,
            L2VPNs, or network slices can be attached.";
         leaf attachment-id {
           type nt:tp-id;
           description
             "Indicates the name of the interface.";
         }
         leaf interface-type {
           type identityref {
             base if:interface-type;
           }
           config false;

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           description
             "The type of the interface.";
         }
         leaf admin-status {
           type boolean;
           description
             "Indicates the administrative status of the SAP.";
         }
         leaf oper-status {
           type boolean;
           description
             "Indicates the operational status.";
         }
         leaf encapsulation-type {
           type identityref {
             base vpn-common:encapsulation-type;
           }
           description
             "Encapsulation type.";
         }
         leaf-list sap-type {
           type identityref {
             base service-type;
           }
           description
             "SAP type.";
         }
         leaf service-description {
           type string;
           description
             "A textual description of the service(s).";
         }
       }
     }

     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 sap-type {
           type identityref {
             base service-type;
           }
           description

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             "Indicates a service type.";
         }
       }
     }

     augment "/nw:networks/nw:network/nw:node" {
       description
         "Parameters for the service attachment point level.";
       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-attachment-point/
      sap:attachment-id

   This subtree specifies the configurations of the nodes in a SAP
   network model.  Unexpected changes to this subtree 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-attachment-point

      Unauthorized access to this subtree can disclose the operational
      state information of the nodes in a SAP network model.

9.  Acknowledgements

   Thanks to Adrian Farrell and Daniel King for the suggestions on the
   names used in a previous version.

10.  References

10.1.  Normative References

   [I-D.ietf-opsawg-vpn-common]
              Barguil, S., Dios, O. G. D., Boucadair, M., and Q. Wu, "A
              Layer 2/3 VPN Common YANG Model", Work in Progress,
              Internet-Draft, draft-ietf-opsawg-vpn-common-12, 29
              September 2021, <https://www.ietf.org/archive/id/draft-
              ietf-opsawg-vpn-common-12.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>.

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

   [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>.

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

   [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>.

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   [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>.

10.2.  Informative References

   [I-D.ietf-opsawg-l2nm]
              Barguil, S., Dios, O. G. D., Boucadair, M., and L. A.
              Munoz, "A Layer 2 VPN Network YANG Model", Work in
              Progress, Internet-Draft, draft-ietf-opsawg-l2nm-09, 20
              October 2021, <https://www.ietf.org/archive/id/draft-ietf-
              opsawg-l2nm-09.txt>.

   [I-D.ietf-opsawg-l3sm-l3nm]
              Barguil, S., Dios, O. G. D., Boucadair, M., Munoz, L. A.,
              and A. Aguado, "A Layer 3 VPN Network YANG Model", Work in
              Progress, Internet-Draft, draft-ietf-opsawg-l3sm-l3nm-18,
              8 October 2021, <https://www.ietf.org/archive/id/draft-
              ietf-opsawg-l3sm-l3nm-18.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-08, 12 July 2021,
              <https://www.ietf.org/archive/id/draft-ietf-teas-enhanced-
              vpn-08.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>.

   [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>.

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   [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>.

   [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>.

   [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>.

   [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>.

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   [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>.

   [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>.

Authors' Addresses

   Oscar Gonzalez de Dios
   Telefonica
   Madrid
   Spain

   Email: oscar.gonzalezdedios@telefonica.com

   Samier Barguil
   Telefonica
   Madrid
   Spain

   Email: samier.barguilgiraldo.ext@telefonica.com

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   Qin Wu
   Huawei
   101 Software Avenue, Yuhua District
   Nanjing
   Jiangsu, 210012
   China

   Email: bill.wu@huawei.com

   Mohamed Boucadair
   Orange
   France

   Email: mohamed.boucadair@orange.com

   Victor Lopez
   Nokia
   Spain

   Email: victor.lopez@nokia.com

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