A YANG Data Model for Layer 2 Virtual Private Network (L2VPN) Service Delivery
RFC 8466

Document Type RFC - Proposed Standard (October 2018; Errata)
Last updated 2019-01-29
Replaces draft-wen-l2sm-l2vpn-service-model
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Internet Engineering Task Force (IETF)                            B. Wen
Request for Comments: 8466                                       Comcast
Category: Standards Track                               G. Fioccola, Ed.
ISSN: 2070-1721                                           Telecom Italia
                                                                  C. Xie
                                                           China Telecom
                                                                L. Jalil
                                                                 Verizon
                                                            October 2018

                         A YANG Data Model for
        Layer 2 Virtual Private Network (L2VPN) Service Delivery

Abstract

   This document defines a YANG data model that can be used to configure
   a Layer 2 provider-provisioned VPN service.  It is up to a management
   system to take this as an input and generate specific configuration
   models to configure the different network elements to deliver the
   service.  How this configuration of network elements is done is out
   of scope for this document.

   The YANG data model defined in this document includes support for
   point-to-point Virtual Private Wire Services (VPWSs) and multipoint
   Virtual Private LAN Services (VPLSs) that use Pseudowires signaled
   using the Label Distribution Protocol (LDP) and the Border Gateway
   Protocol (BGP) as described in RFCs 4761 and 6624.

   The YANG data model defined in this document conforms to the Network
   Management Datastore Architecture defined in RFC 8342.

Status of This Memo

   This is an Internet Standards Track document.

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

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8466.

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Copyright Notice

   Copyright (c) 2018 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 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  . . . . . . . . . . . . . . . . . . . . . . . .   4
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   4
       1.1.1.  Requirements Language . . . . . . . . . . . . . . . .   5
     1.2.  Tree Diagrams . . . . . . . . . . . . . . . . . . . . . .   5
   2.  Definitions . . . . . . . . . . . . . . . . . . . . . . . . .   5
   3.  The Layer 2 VPN Service Model . . . . . . . . . . . . . . . .   7
     3.1.  Layer 2 VPN Service Types . . . . . . . . . . . . . . . .   7
     3.2.  Layer 2 VPN Physical Network Topology . . . . . . . . . .   7
   4.  Service Data Model Usage  . . . . . . . . . . . . . . . . . .   9
   5.  Design of the Data Model  . . . . . . . . . . . . . . . . . .  11
     5.1.  Features and Augmentation . . . . . . . . . . . . . . . .  20
     5.2.  VPN Service Overview  . . . . . . . . . . . . . . . . . .  20
       5.2.1.  VPN Service Type  . . . . . . . . . . . . . . . . . .  21
       5.2.2.  VPN Service Topologies  . . . . . . . . . . . . . . .  22
         5.2.2.1.  Route Target Allocation . . . . . . . . . . . . .  22
         5.2.2.2.  Any-to-Any  . . . . . . . . . . . . . . . . . . .  22
         5.2.2.3.  Hub-and-Spoke . . . . . . . . . . . . . . . . . .  22
         5.2.2.4.  Hub-and-Spoke Disjoint  . . . . . . . . . . . . .  23
       5.2.3.  Cloud Access  . . . . . . . . . . . . . . . . . . . .  24
       5.2.4.  Extranet VPNs . . . . . . . . . . . . . . . . . . . .  27
       5.2.5.  Frame Delivery Service  . . . . . . . . . . . . . . .  28
     5.3.  Site Overview . . . . . . . . . . . . . . . . . . . . . .  30
       5.3.1.  Devices and Locations . . . . . . . . . . . . . . . .  31
       5.3.2.  Site Network Accesses . . . . . . . . . . . . . . . .  32
         5.3.2.1.  Bearer  . . . . . . . . . . . . . . . . . . . . .  33
         5.3.2.2.  Connection  . . . . . . . . . . . . . . . . . . .  33
     5.4.  Site Roles  . . . . . . . . . . . . . . . . . . . . . . .  38

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     5.5.  Site Belonging to Multiple VPNs . . . . . . . . . . . . .  38
       5.5.1.  Site VPN Flavors  . . . . . . . . . . . . . . . . . .  38
         5.5.1.1.  Single VPN Attachment: site-vpn-flavor-single . .  39
         5.5.1.2.  Multi-VPN Attachment: site-vpn-flavor-multi . . .  39
         5.5.1.3.  NNI: site-vpn-flavor-nni  . . . . . . . . . . . .  40
         5.5.1.4.  E2E: site-vpn-flavor-e2e  . . . . . . . . . . . .  41
       5.5.2.  Attaching a Site to a VPN . . . . . . . . . . . . . .  41
         5.5.2.1.  Referencing a VPN . . . . . . . . . . . . . . . .  41
         5.5.2.2.  VPN Policy  . . . . . . . . . . . . . . . . . . .  43
     5.6.  Deciding Where to Connect the Site  . . . . . . . . . . .  48
       5.6.1.  Constraint: Device  . . . . . . . . . . . . . . . . .  49
       5.6.2.  Constraint/Parameter: Site Location . . . . . . . . .  50
       5.6.3.  Constraint/Parameter: Access Type . . . . . . . . . .  51
       5.6.4.  Constraint: Access Diversity  . . . . . . . . . . . .  52
     5.7.  Route Distinguisher and Network Instance Allocation . . .  53
     5.8.  Site-Network-Access Availability  . . . . . . . . . . . .  54
     5.9.  SVC MTU . . . . . . . . . . . . . . . . . . . . . . . . .  56
     5.10. Service . . . . . . . . . . . . . . . . . . . . . . . . .  56
       5.10.1.  Bandwidth  . . . . . . . . . . . . . . . . . . . . .  56
       5.10.2.  QoS  . . . . . . . . . . . . . . . . . . . . . . . .  57
         5.10.2.1.  QoS Classification . . . . . . . . . . . . . . .  57
         5.10.2.2.  QoS Profile  . . . . . . . . . . . . . . . . . .  58
       5.10.3.  Support for BUM  . . . . . . . . . . . . . . . . . .  59
     5.11. Site Management . . . . . . . . . . . . . . . . . . . . .  60
     5.12. MAC Loop Protection . . . . . . . . . . . . . . . . . . .  61
     5.13. MAC Address Limit . . . . . . . . . . . . . . . . . . . .  61
     5.14. Enhanced VPN Features . . . . . . . . . . . . . . . . . .  62
       5.14.1.  Carriers' Carriers . . . . . . . . . . . . . . . . .  62
     5.15. External ID References  . . . . . . . . . . . . . . . . .  63
     5.16. Defining NNIs and Inter-AS Support  . . . . . . . . . . .  64
       5.16.1.  Defining an NNI with the Option A Flavor . . . . . .  66
       5.16.2.  Defining an NNI with the Option B Flavor . . . . . .  70
       5.16.3.  Defining an NNI with the Option C Flavor . . . . . .  73
     5.17. Applicability of L2SM in Inter-provider and Inter-domain
           Orchestration . . . . . . . . . . . . . . . . . . . . . .  74
   6.  Interaction with Other YANG Modules . . . . . . . . . . . . .  76
   7.  Service Model Usage Example . . . . . . . . . . . . . . . . .  77
   8.  YANG Module . . . . . . . . . . . . . . . . . . . . . . . . .  82
   9.  Security Considerations . . . . . . . . . . . . . . . . . . . 152
   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 153
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . . 153
     11.1.  Normative References . . . . . . . . . . . . . . . . . . 153
     11.2.  Informative References . . . . . . . . . . . . . . . . . 155
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . . 157
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . 158

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1.  Introduction

   This document defines a YANG data model for the Layer 2 VPN (L2VPN)
   service.  This model defines service configuration elements that can
   be used in communication protocols between customers and network
   operators.  Those elements can also be used as input to automated
   control and configuration applications and can generate specific
   configuration models to configure the different network elements to
   deliver the service.  How this configuration of network elements is
   done is out of scope for this document.

   Further discussion of the way that services are modeled in YANG and
   the relationship between "customer service models" like the one
   described in this document and configuration models can be found in
   [RFC8309] and [RFC8199].  Sections 4 and 6 also provide more
   information on how this service model could be used and how it fits
   into the overall modeling architecture.

   The YANG data model defined in this document includes support for
   point-to-point Virtual Private Wire Services (VPWSs) and multipoint
   Virtual Private LAN Services (VPLSs) that use Pseudowires signaled
   using the Label Distribution Protocol (LDP) and the Border Gateway
   Protocol (BGP) as described in [RFC4761] and [RFC6624].  It also
   conforms to the Network Management Datastore Architecture (NMDA)
   [RFC8342].

1.1.  Terminology

   The following terms are defined in [RFC6241] and are not redefined
   here:

   o  client

   o  configuration data

   o  server

   o  state data

   The following terms are defined in [RFC7950] and are not redefined
   here:

   o  augment

   o  data model

   o  data node

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   The terminology for describing YANG data models is found in
   [RFC7950].

1.1.1.  Requirements Language

   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.

1.2.  Tree Diagrams

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

2.  Definitions

   This document uses the following terms:

   Service Provider (SP):  The organization (usually a commercial
      undertaking) responsible for operating the network that offers VPN
      services to clients and customers.

   Customer Edge (CE) Device:  Equipment that is dedicated to a
      particular customer and is directly connected to one or more PE
      devices via Attachment Circuits (ACs).  A CE is usually located at
      the customer premises and is usually dedicated to a single VPN,
      although it may support multiple VPNs if each one has separate
      ACs.  The CE devices can be routers, bridges, switches, or hosts.

   Provider Edge (PE) Device:  Equipment managed by the SP that can
      support multiple VPNs for different customers and is directly
      connected to one or more CE devices via ACs.  A PE is usually
      located at an SP Point of Presence (POP) and is managed by the SP.

   Virtual Private LAN Service (VPLS):  A VPLS is a provider service
      that emulates the full functionality of a traditional LAN.  A VPLS
      makes it possible to interconnect several LAN segments over a
      packet switched network (PSN) and makes the remote LAN segments
      behave as one single LAN.

   Virtual Private Wire Service (VPWS):  A VPWS is a point-to-point
      circuit (i.e., link) connecting two CE devices.  The link is
      established as a logical Layer 2 circuit through a PSN.  The CE in
      the customer network is connected to a PE in the provider network
      via an AC: the AC is either a physical or logical circuit.  A VPWS

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      differs from a VPLS in that the VPLS is point-to-multipoint while
      the VPWS is point-to-point.  In some implementations, a set of
      VPWSs is used to create a multi-site L2VPN network.

   Pseudowire (PW):  A Pseudowire is an emulation of a native service
      over a PSN.  The native service may be ATM, Frame Relay, Ethernet,
      low-rate Time-Division Multiplexing (TDM), or Synchronous Optical
      Network / Synchronous Digital Hierarchy (SONET/SDH), while the PSN
      may be MPLS, IP (either IPv4 or IPv6), or Layer 2 Tunneling
      Protocol version 3 (L2TPv3).

   MAC-VRF:  A Virtual Routing and Forwarding table for Media Access
      Control (MAC) addresses on a PE.  It is sometimes also referred to
      as a Virtual Switching Instance (VSI).

   UNI:  User-to-Network Interface.  The physical demarcation point
      between the customer's area of responsibility and the provider's
      area of responsibility.

   NNI:  Network-to-Network Interface.  A reference point representing
      the boundary between two networks that are operated as separate
      administrative domains.  The two networks may belong to the same
      provider or to two different providers.

   This document uses the following abbreviations:

   BSS:  Business Support System

   BUM:  Broadcast, Unknown Unicast, or Multicast

   CoS:  Class of Service

   LAG:  Link Aggregation Group

   LLDP:  Link Layer Discovery Protocol

   OAM:  Operations, Administration, and Maintenance

   OSS:  Operations Support System

   PDU:  Protocol Data Unit

   QoS:  Quality of Service

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3.  The Layer 2 VPN Service Model

   A Layer 2 VPN (L2VPN) service is a collection of sites that are
   authorized to exchange traffic between each other over a shared
   infrastructure of a common technology.  The L2VPN Service Model
   (L2SM) described in this document provides a common understanding of
   how the corresponding L2VPN service is to be deployed over the shared
   infrastructure.

   This document presents the L2SM using the YANG data modeling language
   [RFC7950] as a formal language that is both human readable and
   parsable by software for use with protocols such as the Network
   Configuration Protocol (NETCONF) [RFC6241] and RESTCONF [RFC8040].

   This service model is limited to VPWS-based VPNs and VPLS-based VPNs
   as described in [RFC4761] and [RFC6624] and to Ethernet VPNs (EVPNs)
   as described in [RFC7432].

3.1.  Layer 2 VPN Service Types

   From a technology perspective, a set of basic L2VPN service types
   include:

   o  Point-to-point VPWSs that use LDP-signaled Pseudowires or
      L2TP-signaled Pseudowires [RFC6074].

   o  Multipoint VPLSs that use LDP-signaled Pseudowires or
      L2TP-signaled Pseudowires [RFC6074].

   o  Multipoint VPLSs that use a BGP control plane as described in
      [RFC4761] and [RFC6624].

   o  IP-only LAN Services (IPLSs) that are a functional subset of VPLS
      services [RFC7436].

   o  BGP MPLS-based EVPN services as described in [RFC7432] and
      [RFC7209].

   o  EVPN VPWSs as specified in [RFC8214].

3.2.  Layer 2 VPN Physical Network Topology

   Figure 1 below depicts a typical SP's physical network topology.
   Most SPs have deployed an IP, MPLS, or Segment Routing (SR)
   multi-service core infrastructure.  Ingress Layer 2 service frames
   will be mapped to either an Ethernet Pseudowire (e.g., Pseudowire
   Emulation Edge to Edge (PWE3)) or a Virtual Extensible Local Area

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   Network (VXLAN) PE-to-PE tunnel.  The details of these tunneling
   mechanisms are left to the provider's discretion and are not part of
   the L2SM.

   An L2VPN provides end-to-end Layer 2 connectivity over this
   multi-service core infrastructure between two or more customer
   locations or a collection of sites.  ACs are placed between CE
   devices and PE devices that backhaul Layer 2 service frames from the
   customer over the access network to the provider network or remote
   site.  The demarcation point (i.e., UNI) between the customer and the
   SP can be placed between either (1) customer nodes and the CE device
   or (2) the CE device and the PE device.  The actual bearer connection
   between the CE and the PE will be described in the L2SM.

   The SP may also choose a "seamless MPLS" approach to expand the PWE3
   or VXLAN tunnel between sites.

   The SP may leverage Multiprotocol BGP (MP-BGP) to autodiscover and
   signal the PWE3 or VXLAN tunnel endpoints.

             Site A  |                          |Site B
    ---     ----     |        VXLAN/PW          |               ---
   |   |   |    |    |<------------------------>|              |   |
   | C +---+ CE |    |                          |              | C |
   |   |   |    |    |         ---------        |              |   |
    ---     ----\    |        (         )       |              /---
                 \  -|--     (           )     -|--     ----  /
                  \|    |   (             )   |    |   |    |/
                   | PE +---+ IP/MPLS/SR  +---+ PE +---+ CE |
                  /|    |   (  Network    )   |    |   |    |\
                 /  ----     (           )     ----     ----  \
    ---     ----/             (         )                      \---
   |   |   |    |              ----+----                       |   |
   | C +---+ CE |                  |                           | C |
   |   |   |    |                --+--                         |   |
    ---     ----                | PE  |                         ---
                                 --+--
                                   |      Site C
                                 --+--
                                | CE  |
                                 --+--
                                   |
                                 --+--
                                |  C  |
                                 -----

            Figure 1: Reference Network for the Use of the L2SM

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   From the customer's perspective, however, all the CE devices are
   connected over a simulated LAN environment as shown in Figure 2.
   Broadcast and multicast packets are sent to all participants in the
   same bridge domain.

                        CE---+----+-----+---CE
                             |    |     |
                             |    |     |
                             |    |     |
                        CE---+    CE    +---CE

                  Figure 2: Customer's View of the L2VPN

4.  Service Data Model Usage

   The L2SM provides an abstracted interface to request, configure, and
   manage the components of an L2VPN service.  The model is used by a
   customer who purchases connectivity and other services from an SP to
   communicate with that SP.

   A typical usage for this model is as an input to an orchestration
   layer that is responsible for translating it into configuration
   commands for the network elements that deliver/enable the service.
   The network elements may be routers, but also servers (like
   Authentication, Authorization, and Accounting (AAA)) that are
   necessary within the network.

   The configuration of network elements may be done using the Command
   Line Interface (CLI) or any other configuration (or "southbound")
   interface such as NETCONF [RFC6241] in combination with device-
   specific and protocol-specific YANG data models.

   This way of using the service model is illustrated in Figure 3 and is
   described in more detail in [RFC8309] and [RFC8199].  The split of
   the orchestration function between a "service orchestrator" and a
   "network orchestrator" is clarified in [RFC8309].  The usage of this
   service model is not limited to this example: it can be used by any
   component of the management system but not directly by network
   elements.

   The usage and structure of this model should be compared to the
   Layer 3 VPN service model defined in [RFC8299].

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          ----------------------------
         | Customer Service Requester |
          ----------------------------
              |
              |
        L2SM  |
              |
              |
            -----------------------
           | Service Orchestration |
            -----------------------
              |
              |     Service             +-------------+
              |     Delivery    +------>| Application |
              |     Model       |       |   BSS/OSS   |
              |                 V       +-------------+
            -----------------------
           | Network Orchestration |
            -----------------------
              |            |
      +----------------+   |
      | Config manager |   |
      +----------------+   |  Device
              |            |  Models
              |            |
   --------------------------------------------
                     Network
                                 +++++++
                                 + AAA +
                                 +++++++

         ++++++++   Bearer    ++++++++           ++++++++      ++++++++
         + CE A + ----------- + PE A +           + PE B + ---- + CE B +
         ++++++++  Connection ++++++++           ++++++++      ++++++++

                    Site A                               Site B

         Figure 3: Reference Architecture for the Use of the L2SM

   The Metro Ethernet Forum (MEF) [MEF-6] has also developed an
   architecture for network management and operations, but the work of
   the MEF embraces all aspects of lifecycle service orchestration,
   including billing, Service Level Agreements (SLAs), order management,
   and lifecycle management.  The IETF's work on service models is
   typically smaller and offers a simple, self-contained service YANG
   module.  See [RFC8309] for more details.

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5.  Design of the Data Model

   The L2SM is structured in a way that allows the provider to list
   multiple circuits of various service types for the same customer.  A
   circuit represents an end-to-end connection between two or more
   customer locations.

   The YANG module is divided into two main containers: "vpn-services"
   and "sites".  The "vpn-svc" container under vpn-services defines
   global parameters for the VPN service for a specific customer.

   A site contains at least one network access (i.e., site network
   accesses providing access to the sites, as defined in Section 5.3.2),
   and there may be multiple network accesses in the case of
   multihoming.  Site-to-network-access attachment is done through a
   bearer with a Layer 2 connection on top.  The bearer refers to
   properties of the attachment that are below Layer 2, while the
   connection refers to Layer 2 protocol-oriented properties.  The
   bearer may be allocated dynamically by the SP, and the customer may
   provide some constraints or parameters to drive the placement.

   Authorization of traffic exchanges is done through what we call a VPN
   policy or VPN topology that defines routing exchange rules between
   sites.

   End-to-end multi-segment connectivity can be realized by using a
   combination of per-site connectivity and per-segment connectivity at
   different segments.

   Figure 4 shows the overall structure of the YANG module:

   module: ietf-l2vpn-svc
   +--rw l2vpn-svc
     +--rw vpn-profiles
     |  +--rw valid-provider-identifiers
     |     +--rw cloud-identifier*  string{cloud-access}?
     |     +--rw qos-profile-identifier* string
     |     +--rw bfd-profile-identifier* string
     |     +--rw remote-carrier-identifier* string
     +--rw vpn-services
     |  +--rw vpn-service* [vpn-id]
     |     +--rw vpn-id                      svc-id
     |     +--rw vpn-svc-type?               identityref
     |     +--rw customer-name?              string
     |     +--rw svc-topo?                   identityref
     |     +--rw cloud-accesses {cloud-access}?
     |     |  +--rw cloud-access* [cloud-identifier]
     |     |     +--rw cloud-identifier

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     |     |     |    -> /l2vpn-svc/vpn-profiles/
     |     |     |      valid-provider-identifiers/cloud-identifier
     |     |     +--rw (list-flavor)?
     |     |        +--:(permit-any)
     |     |        |  +--rw permit-any?         empty
     |     |        +--:(deny-any-except)
     |     |        |  +--rw permit-site*
     |     |        |  :    -> /l2vpn-svc/sites/site/site-id
     |     |        +--:(permit-any-except)
     |     |           +--rw deny-site*
     |     |                -> /l2vpn-svc/sites/site/site-id
     |     +--rw frame-delivery {frame-delivery}?
     |     |  +--rw customer-tree-flavors
     |     |  |  +--rw tree-flavor*   identityref
     |     |  +--rw bum-frame-delivery
     |     |  |  +--rw bum-frame-delivery* [frame-type]
     |     |  |     +--rw frame-type       identityref
     |     |  |     +--rw delivery-mode?   identityref
     |     |  +--rw multicast-gp-port-mapping    identityref
     |     +--rw extranet-vpns {extranet-vpn}?
     |     |  +--rw extranet-vpn* [vpn-id]
     |     |     +--rw vpn-id              svc-id
     |     |     +--rw local-sites-role?   identityref
     |     +--rw ce-vlan-preservation        boolean
     |     +--rw ce-vlan-cos-preservation    boolean
     |     +--rw carrierscarrier?            boolean {carrierscarrier}?
     +--rw sites
       +--rw site* [site-id]
        +--rw site-id                                string
        +--rw site-vpn-flavor?                       identityref
        +--rw devices
        |  +--rw device* [device-id]
        |     +--rw device-id     string
        |     +--rw location
        |     |    -> ../../../locations/location/location-id
        |     +--rw management
        |        +--rw transport?   identityref
        |        +--rw address?     inet:ip-address
        +--rw management
        |  +--rw type    identityref
        +--rw locations
        |  +--rw location* [location-id]
        |     +--rw location-id     string
        |     +--rw address?        string
        |     +--rw postal-code?    string
        |     +--rw state?          string
        |     +--rw city?           string
        |     +--rw country-code?   string

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        +--rw site-diversity {site-diversity}?
        |  +--rw groups
        |     +--rw group* [group-id]
        |        +--rw group-id    string
        +--rw vpn-policies
        |  +--rw vpn-policy* [vpn-policy-id]
        |     +--rw vpn-policy-id    string
        |     +--rw entries* [id]
        |        +--rw id         string
        |        +--rw filters
        |        |  +--rw filter* [type]
        |        |     +--rw type       identityref
        |        |     +--rw lan-tag*   uint32 {lan-tag}?
        |        +--rw vpn* [vpn-id]
        |           +--rw vpn-id
        |           |    -> /l2vpn-svc/vpn-services/
        |           |            vpn-service/vpn-id
        |           +--rw site-role?   identityref
        +--rw service
        |  +--rw qos {qos}?
        |  |  +--rw qos-classification-policy
        |  |  |  +--rw rule* [id]
        |  |  |     +--rw id                   string
        |  |  |     +--rw (match-type)?
        |  |  |     |  +--:(match-flow)
        |  |  |     |  |  +--rw match-flow
        |  |  |     |  |     +--rw dscp?           inet:dscp
        |  |  |     |  |     +--rw dot1q?          uint16
        |  |  |     |  |     +--rw pcp?            uint8
        |  |  |     |  |     +--rw src-mac?        yang:mac-address
        |  |  |     |  |     +--rw dst-mac?        yang:mac-address
        |  |  |     |  |     +--rw color-type?     identityref
        |  |  |     |  |     +--rw target-sites*
        |  |  |     |  |     |               svc-id {target-sites}?
        |  |  |     |  |     +--rw any?            empty
        |  |  |     |  |     +--rw vpn-id?         svc-id
        |  |  |     |  +--:(match-application)
        |  |  |     |     +--rw match-application?   identityref
        |  |  |     +--rw target-class-id?     string
        |  |  +--rw qos-profile
        |  |     +--rw (qos-profile)?
        |  |        +--:(standard)
        |  |        |  +--rw profile?
        |  |        |       -> /l2vpn-svc/vpn-profiles/
        |  |        |              valid-provider-identifiers/
        |  |        |              qos-profile-identifier
        |  |        +--:(custom)
        |  |           +--rw classes {qos-custom}?

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        |  |              +--rw class* [class-id]
        |  |                 +--rw class-id        string
        |  |                 +--rw direction?      identityref
        |  |                 +--rw policing?       identityref
        |  |                 +--rw byte-offset?    uint16
        |  |                 +--rw frame-delay
        |  |                 |  +--rw (flavor)?
        |  |                 |     +--:(lowest)
        |  |                 |     |  +--rw use-lowest-latency? empty
        |  |                 |     +--:(boundary)
        |  |                 |        +--rw delay-bound?     uint16
        |  |                 +--rw frame-jitter
        |  |                 |  +--rw (flavor)?
        |  |                 |     +--:(lowest)
        |  |                 |     |  +--rw use-lowest-jitter? empty
        |  |                 |     +--:(boundary)
        |  |                 |        +--rw delay-bound?     uint32
        |  |                 +--rw frame-loss
        |  |                 |  +--rw rate?   decimal64
        |  |                 +--rw bandwidth
        |  |                    +--rw guaranteed-bw-percent decimal64
        |  |                    +--rw end-to-end?           empty
        |  +--rw carrierscarrier {carrierscarrier}?
        |     +--rw signaling-type?   identityref
        +--rw broadcast-unknown-unicast-multicast {bum}?
        |  +--rw multicast-site-type?            enumeration
        |  +--rw multicast-gp-address-mapping* [id]
        |  |  +--rw id                 uint16
        |  |  +--rw vlan-id            uint16
        |  |  +--rw mac-gp-address     yang:mac-address
        |  |  +--rw port-lag-number?   uint32
        |  +--rw bum-overall-rate?     uint32
        |  +--rw bum-rate-per-type* [type]
        |     +--rw type    identityref
        |     +--rw rate?   uint32
        +--rw mac-loop-prevention {mac-loop-prevention}?
        |  +--rw protection-type?   identityref
        |  +--rw frequency?         uint32
        |  +--rw retry-timer?       uint32
        +--rw access-control-list
        |  +--rw mac* [mac-address]
        |     +--rw mac-address    yang:mac-address
        +--ro actual-site-start?   yang:date-and-time
        +--ro actual-site-stop?    yang:date-and-time
        +--rw bundling-type?       identityref
        +--rw default-ce-vlan-id   uint32
        +--rw site-network-accesses
           +--rw site-network-access* [network-access-id]

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           +--rw network-access-id                 string
           +--rw remote-carrier-name?              string
           +--rw type?                             identityref
           +--rw (location-flavor)
           |  +--:(location)
           |  |  +--rw location-reference?
           |  |       -> ../../../locations/location/
           |  |               location-id
           |  +--:(device)
           |     +--rw device-reference?
           |          -> ../../../devices/device/device-id
           +--rw access-diversity {site-diversity}?
           |  +--rw groups
           |  |  +--rw group* [group-id]
           |  |     +--rw group-id    string
           |  +--rw constraints
           |     +--rw constraint* [constraint-type]
           |        +--rw constraint-type    identityref
           |        +--rw target
           |           +--rw (target-flavor)?
           |              +--:(id)
           |              |  +--rw group* [group-id]
           |              |     +--rw group-id    string
           |              +--:(all-accesses)
           |              |  +--rw all-other-accesses?   empty
           |              +--:(all-groups)
           |                 +--rw all-other-groups?     empty
           +--rw bearer
           |  +--rw requested-type {requested-type}?
           |  |  +--rw type?     string
           |  |  +--rw strict?   boolean
           |  +--rw always-on?         boolean {always-on}?
           |  +--rw bearer-reference?  string {bearer-reference}?
           +--rw connection
           |  +--rw encapsulation-type?    identityref
           |  +--rw eth-inf-type?          identityref
           |  +--rw tagged-interface
           |  |  +--rw type?               identityref
           |  |  +--rw dot1q-vlan-tagged {dot1q}?
           |  |  |  +--rw tg-type?    identityref
           |  |  |  +--rw cvlan-id    uint16
           |  |  +--rw priority-tagged
           |  |  |  +--rw tag-type?   identityref
           |  |  +--rw qinq {qinq}?
           |  |  |  +--rw tag-type?   identityref
           |  |  |  +--rw svlan-id    uint16
           |  |  |  +--rw cvlan-id    uint16
           |  |  +--rw qinany {qinany}?

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           |  |  |  +--rw tag-type?   identityref
           |  |  |  +--rw svlan-id    uint16
           |  |  +--rw vxlan {vxlan}?
           |  |     +--rw vni-id       uint32
           |  |     +--rw peer-mode?   identityref
           |  |     +--rw peer-list* [peer-ip]
           |  |        +--rw peer-ip    inet:ip-address
           |  +--rw untagged-interface
           |  |  +--rw speed?                 uint32
           |  |  +--rw mode?                  neg-mode
           |  |  +--rw phy-mtu?               uint32
           |  |  +--rw lldp?                  boolean
           |  |  +--rw oam-802.3ah-link {oam-3ah}?
           |  |  |  +--rw enabled?   boolean
           |  |  +--rw uni-loop-prevention?   boolean
           |  +--rw lag-interfaces {lag-interface}?
           |  |  +--rw lag-interface* [index]
           |  |     +--rw index    string
           |  |     +--rw lacp {lacp}?
           |  |        +--rw enabled?           boolean
           |  |        +--rw mode?              neg-mode
           |  |        +--rw speed?             uint32
           |  |        +--rw mini-link-num?     uint32
           |  |        +--rw system-priority?   uint16
           |  |        +--rw micro-bfd {micro-bfd}?
           |  |        |  +--rw enabled?      enumeration
           |  |        |  +--rw interval?     uint32
           |  |        |  +--rw hold-timer?   uint32
           |  |        +--rw bfd {bfd}?
           |  |        |  +--rw enabled?      boolean
           |  |        |  +--rw (holdtime)?
           |  |        |     +--:(profile)
           |  |        |     |  +--rw profile-name?
           |  |        |     |    -> /l2vpn-svc/
           |  |        |     |         vpn-profiles/
           |  |        |     |        valid-provider-identifiers/
           |  |        |     |       bfd-profile-identifier
           |  |        |     +--:(fixed)
           |  |        |        +--rw fixed-value?    uint32
           |  |        +--rw member-links
           |  |        |  +--rw member-link* [name]
           |  |        |     +--rw name                string
           |  |        |     +--rw speed?              uint32
           |  |        |     +--rw mode?               neg-mode
           |  |        |     +--rw link-mtu?           uint32
           |  |        |     +--rw oam-802.3ah-link {oam-3ah}?
           |  |        |        +--rw enabled?  boolean
           |  |        +--rw flow-control?      boolean

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           |  |        +--rw lldp?              boolean
           |  +--rw cvlan-id-to-svc-map* [svc-id]
           |  |  +--rw svc-id
           |  |  |    -> /l2vpn-svc/vpn-services/vpn-service/
           |  |  |           vpn-id
           |  |  +--rw cvlan-id* [vid]
           |  |     +--rw vid    uint16
           |  +--rw l2cp-control {l2cp-control}?
           |  |  +--rw stp-rstp-mstp?    control-mode
           |  |  +--rw pause?            control-mode
           |  |  +--rw lacp-lamp?        control-mode
           |  |  +--rw link-oam?         control-mode
           |  |  +--rw esmc?             control-mode
           |  |  +--rw l2cp-802.1x?      control-mode
           |  |  +--rw e-lmi?            control-mode
           |  |  +--rw lldp?             boolean
           |  |  +--rw ptp-peer-delay?   control-mode
           |  |  +--rw garp-mrp?         control-mode
           |  +--rw oam {oam}
           |     +--rw md-name         string
           |     +--rw md-level        uint16
           |     +--rw cfm-802.1-ag* [maid]
           |     |  +--rw maid                     string
           |     |  +--rw mep-id?                  uint32
           |     |  +--rw mep-level?               uint32
           |     |  +--rw mep-up-down?             enumeration
           |     |  +--rw remote-mep-id?           uint32
           |     |  +--rw cos-for-cfm-pdus?        uint32
           |     |  +--rw ccm-interval?            uint32
           |     |  +--rw ccm-holdtime?            uint32
           |     |  +--rw alarm-priority-defect?   identityref
           |     |  +--rw ccm-p-bits-pri?       ccm-priority-type
           |     +--rw y-1731* [maid]
           |        +--rw maid                           string
           |        +--rw mep-id?                        uint32
           |        +--rw type?                       identityref
           |        +--rw remote-mep-id?                 uint32
           |        +--rw message-period?                uint32
           |        +--rw measurement-interval?          uint32
           |        +--rw cos?                           uint32
           |        +--rw loss-measurement?              boolean
           |        +--rw synthetic-loss-measurement?    boolean
           |        +--rw delay-measurement
           |        |  +--rw enable-dm?   boolean
           |        |  +--rw two-way?     boolean
           |        +--rw frame-size?                    uint32
           |        +--rw session-type?               enumeration
           +--rw availability

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           |  +--rw access-priority?   uint32
           |  +--rw (redundancy-mode)?
           |     +--:(single-active)
           |     |  +--rw single-active?     empty
           |     +--:(all-active)
           |        +--rw all-active?        empty
           +--rw vpn-attachment
           |  +--rw (attachment-flavor)
           |     +--:(vpn-id)
           |     |  +--rw vpn-id?
           |     |  |    -> /l2vpn-svc/vpn-services/
           |     |  |            vpn-service/vpn-id
           |     |  +--rw site-role?              identityref
           |     +--:(vpn-policy-id)
           |        +--rw vpn-policy-id?
           |             -> ../../../../vpn-policies/
           |                     vpn-policy/vpn-policy-id
           +--rw service
           |  +--rw svc-bandwidth {input-bw}?
           |  |  +--rw bandwidth* [direction type]
           |  |     +--rw direction    identityref
           |  |     +--rw type         identityref
           |  |     +--rw cos-id?      uint8
           |  |     +--rw vpn-id?      svc-id
           |  |     +--rw cir          uint64
           |  |     +--rw cbs          uint64
           |  |     +--rw eir?         uint64
           |  |     +--rw ebs?         uint64
           |  |     +--rw pir?         uint64
           |  |     +--rw pbs?         uint64
           |  +--rw svc-mtu            uint16
           |  +--rw qos {qos}?
           |  |  +--rw qos-classification-policy
           |  |  |  +--rw rule* [id]
           |  |  |     +--rw id                   string
           |  |  |     +--rw (match-type)?
           |  |  |     |  +--:(match-flow)
           |  |  |     |  |  +--rw match-flow
           |  |  |     |  |     +--rw dscp?           inet:dscp
           |  |  |     |  |     +--rw dot1q?          uint16
           |  |  |     |  |     +--rw pcp?            uint8
           |  |  |     |  |     +--rw src-mac?  yang:mac-address
           |  |  |     |  |     +--rw dst-mac?  yang:mac-address
           |  |  |     |  |     +--rw color-type?     identityref
           |  |  |     |  |     +--rw target-sites*
           |  |  |     |  |     |          svc-id {target-sites}?
           |  |  |     |  |     +--rw any?            empty
           |  |  |     |  |     +--rw vpn-id?         svc-id

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           |  |  |     |  +--:(match-application)
           |  |  |     |     +--rw match-application? identityref
           |  |  |     +--rw target-class-id?     string
           |  |  +--rw qos-profile
           |  |     +--rw (qos-profile)?
           |  |        +--:(standard)
           |  |        |  +--rw profile?
           |  |        |       -> /l2vpn-svc/vpn-profiles/
           |  |        |              valid-provider-identifiers/
           |  |        |              qos-profile-identifier
           |  |        +--:(custom)
           |  |           +--rw classes {qos-custom}?
           |  |              +--rw class* [class-id]
           |  |                 +--rw class-id        string
           |  |                 +--rw direction?      identityref
           |  |                 +--rw policing?       identityref
           |  |                 +--rw byte-offset?    uint16
           |  |                 +--rw frame-delay
           |  |                 |  +--rw (flavor)?
           |  |                 |     +--:(lowest)
           |  |                 |     |  +--rw use-lowest-latency?
           |  |                 |     |                     empty
           |  |                 |     +--:(boundary)
           |  |                 |        +--rw delay-bound? uint16
           |  |                 +--rw frame-jitter
           |  |                 |  +--rw (flavor)?
           |  |                 |     +--:(lowest)
           |  |                 |     |  +--rw use-lowest-jitter?
           |  |                 |     |                     empty
           |  |                 |     +--:(boundary)
           |  |                 |        +--rw delay-bound? uint32
           |  |                 +--rw frame-loss
           |  |                 |  +--rw rate?   decimal64
           |  |                 +--rw bandwidth
           |  |                    +--rw guaranteed-bw-percent
           |  |                    |                    decimal64
           |  |                    +--rw end-to-end?       empty
           |  +--rw carrierscarrier {carrierscarrier}?
           |     +--rw signaling-type?   identityref
           +--rw broadcast-unknown-unicast-multicast {bum}?
           |  +--rw multicast-site-type?            enumeration
           |  +--rw multicast-gp-address-mapping* [id]
           |  |  +--rw id                 uint16
           |  |  +--rw vlan-id            uint16
           |  |  +--rw mac-gp-address     yang:mac-address
           |  |  +--rw port-lag-number?   uint32
           |  +--rw bum-overall-rate?               uint32
           |  +--rw bum-rate-per-type* [type]

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           |     +--rw type    identityref
           |     +--rw rate?   uint32
           +--rw mac-loop-prevention {mac-loop-prevention}?
           |  +--rw protection-type?   identityref
           |  +--rw frequency?         uint32
           |  +--rw retry-timer?       uint32
           +--rw access-control-list
           |  +--rw mac* [mac-address]
           |     +--rw mac-address    yang:mac-address
           +--rw mac-addr-limit
           +--rw limit-number?    uint16
           +--rw time-interval?   uint32
           +--rw action?          identityref

              Figure 4: Overall Structure of the YANG Module

5.1.  Features and Augmentation

   The model defined in this document implements many features that
   allow implementations to be modular.  As an example, the Layer 2
   protocol parameters (Section 5.3.2.2) proposed to the customer may
   also be enabled through features.  This model also defines some
   features for options that are more advanced, such as support for
   extranet VPNs (Section 5.2.4), site diversity (Section 5.3), and QoS
   (Section 5.10.2).

   In addition, as for any YANG data model, this service model can be
   augmented to implement new behaviors or specific features.  For
   example, this model defines VXLAN [RFC7348] for Ethernet packet
   encapsulation; if VXLAN encapsulation does not fulfill all
   requirements for describing the service, new options can be added
   through augmentation.

5.2.  VPN Service Overview

   The vpn-service list item contains generic information about the VPN
   service.  The vpn-id in the vpn-service list refers to an internal
   reference for this VPN service.  This identifier is purely internal
   to the organization responsible for the VPN service.

   The vpn-service list is composed of the following characteristics:

   Customer information (customer-name):  Used to identify the customer.

   VPN service type (vpn-svc-type):  Used to indicate the VPN service
      type.  The identifier is an identity allowing any encoding for the
      local administration of the VPN service.  Note that another
      identity can be an extension of the base identity.

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   Cloud access (cloud-access):  All sites in the L2VPN SHOULD be
      permitted to access the cloud by default.  The "cloud-access"
      container provides parameters for authorization rules.  A cloud
      identifier is used to reference the target service.  This
      identifier is local to each administration.

   Service topology (svc-topo):  Used to identify the type of VPN
      service topology that is required.

   Frame delivery service (frame-delivery):  Defines the frame delivery
      support required for the L2VPN, e.g., multicast delivery, unicast
      delivery, or broadcast delivery.

   Extranet VPN (extranet-vpns):  Indicates that a particular VPN needs
      access to resources located in another VPN.

5.2.1.  VPN Service Type

   The "vpn-svc-type" parameter defines the service type for provider-
   provisioned L2VPNs.  The current version of the model supports six
   flavors:

   o  Point-to-point VPWSs connecting two customer sites.

   o  Point-to-point or point-to-multipoint VPWSs connecting a set of
      customer sites [RFC8214].

   o  Multipoint VPLSs connecting a set of customer sites.

   o  Multipoint VPLSs connecting one or more root sites and a set of
      leaf sites but preventing inter-leaf-site communication.

   o  EVPN services [RFC7432] connecting a set of customer sites.

   o  EVPN VPWSs between two customer sites or a set of customer sites
      as specified in [RFC8214].

   Other L2VPN service types could be included by augmentation.  Note
   that an Ethernet Private Line (EPL) service or an Ethernet Virtual
   Private Line (EVPL) service is an Ethernet Line (E-Line) service
   [MEF-6]or a point-to-point Ethernet Virtual Circuit (EVC) service,
   while an Ethernet Private LAN (EP-LAN) service or an Ethernet Virtual
   Private LAN (EVP-LAN) service is an Ethernet LAN (E-LAN) service
   [MEF-6] or a multipoint-to-multipoint EVC service.

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5.2.2.  VPN Service Topologies

   The types of VPN service topologies discussed below can be used for
   configuration if needed.  The module described in this document
   currently supports any-to-any, Hub-and-Spoke (where Hubs can exchange
   traffic), and Hub-and-Spoke Disjoint (where Hubs cannot exchange
   traffic).  New topologies could be added by augmentation.  By
   default, the any-to-any VPN service topology is used.

5.2.2.1.  Route Target Allocation

   A Layer 2 PE-based VPN (such as a VPLS-based VPN or an EVPN that uses
   BGP as its signaling protocol) can be built using Route Targets (RTs)
   as described in [RFC4364] and [RFC7432].  The management system is
   expected to automatically allocate a set of RTs upon receiving a VPN
   service creation request.  How the management system allocates RTs is
   out of scope for this document, but multiple ways could be envisaged,
   as described in Section 6.2.1.1 of [RFC8299].

5.2.2.2.  Any-to-Any

     +--------------------------------------------------------------+
     |  VPN1_Site 1 ------ PE1               PE2 ------ VPN1_Site 2 |
     |                                                              |
     |  VPN1_Site 3 ------ PE3               PE4 ------ VPN1_Site 4 |
     +--------------------------------------------------------------+

                 Figure 5: Any-to-Any VPN Service Topology

   In the any-to-any VPN service topology, all VPN sites can communicate
   with each other without any restrictions.  The management system that
   receives an any-to-any L2VPN service request through this model is
   expected to assign and then configure the MAC-VRF and RTs on the
   appropriate PEs.  In the any-to-any case, a single RT is generally
   required, and every MAC-VRF imports and exports this RT.

5.2.2.3.  Hub-and-Spoke

     +---------------------------------------------------------------+
     |   Hub_Site 1 ------ PE1               PE2 ------ Spoke_Site 1 |
     |                          +------------------------------------+
     |                          |
     |                          +------------------------------------+
     |   Hub_Site 2 ------ PE3               PE4 ------ Spoke_Site 2 |
     +---------------------------------------------------------------+

               Figure 6: Hub-and-Spoke VPN Service Topology

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   In the Hub-and-Spoke VPN service topology,

   o  all Spoke sites can communicate only with Hub sites (i.e., Spoke
      sites cannot communicate with each other).

   o  Hubs can communicate with each other.

   The management system that receives a Hub-and-Spoke L2VPN service
   request through this model is expected to assign and then configure
   the MAC-VRF and RTs on the appropriate PEs.  In the Hub-and-Spoke
   case, two RTs are generally required (one RT for Hub routes and one
   RT for Spoke routes).  A Hub MAC-VRF that connects Hub sites will
   export Hub routes with the Hub RT and will import Spoke routes
   through the Spoke RT.  It will also import the Hub RT to allow
   Hub-to-Hub communication.  A Spoke MAC-VRF that connects Spoke sites
   will export Spoke routes with the Spoke RT and will import Hub routes
   through the Hub RT.

5.2.2.4.  Hub-and-Spoke Disjoint

     +---------------------------------------------------------------+
     |   Hub_Site 1 ------ PE1               PE2 ------ Spoke_Site 1 |
     +--------------------------+  +---------------------------------+
                                |  |
     +--------------------------+  +---------------------------------+
     |   Hub_Site 2 ------ PE3               PE4 ------ Spoke_Site 2 |
     +---------------------------------------------------------------+

           Figure 7: Hub-and-Spoke-Disjoint VPN Service Topology

   In the Hub-and-Spoke-Disjoint VPN service topology,

   o  all Spoke sites can communicate only with Hub sites (i.e., Spoke
      sites cannot communicate with each other).

   o  Hubs cannot communicate with each other.

   The management system that receives a Hub-and-Spoke-Disjoint L2VPN
   service request through this model is expected to assign and then
   configure the VRF and RTs on the appropriate PEs.  In the
   Hub-and-Spoke-Disjoint case, at least two RTs are required for Hubs
   and Spokes, respectively (at least one RT for Hub routes and at least
   one RT for Spoke routes).  A Hub VRF that connects Hub sites will
   export Hub routes with the Hub RT and will import Spoke routes
   through the Spoke RT.  A Spoke VRF that connects Spoke sites will
   export Spoke routes with the Spoke RT and will import Hub routes
   through the Hub RT.

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   The management system MUST take into account constraints on
   Hub-and-Spoke connections, as in the previous case.

   Hub-and-Spoke Disjoint can also be seen as multiple Hub-and-Spoke
   VPNs (one per Hub) that share a common set of Spoke sites.

5.2.3.  Cloud Access

   This model provides cloud access configuration through the
   cloud-access container.  The usage of cloud-access is targeted for
   public cloud access and Internet access.  The cloud-access container
   provides parameters for authorization rules.  Note that this model
   considers that public cloud and public Internet access share some
   commonality; therefore, it does not distinguish Internet access from
   cloud access.  If needed, a different label for Internet access could
   be added by augmentation.

   Private cloud access may be addressed through the site container as
   described in Section 5.3, with usage consistent with sites of
   type "NNI".

   A cloud identifier is used to reference the target service.  This
   identifier is local to each administration.

   By default, all sites in the L2VPN SHOULD be permitted to access the
   cloud or the Internet.  If restrictions are required, a user MAY
   configure some limitations for some sites or nodes by using policies,
   i.e., the "permit-site" or "deny-site" leaf-list.  The permit-site
   leaf-list defines the list of sites authorized for cloud access.  The
   deny-site leaf-list defines the list of sites denied for cloud
   access.  The model supports both "deny-any-except" and
   "permit-any-except" authorization.

   How the restrictions will be configured on network elements is out of
   scope for this document.

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                        L2VPN
              ++++++++++++++++++++++++++++++++     ++++++++++++
              +            Site 3            + --- +  Cloud 1 +
              + Site 1                       +     ++++++++++++
              +                              +
              + Site 2                       + --- ++++++++++++
              +                              +     + Internet +
              +            Site 4            +     ++++++++++++
              ++++++++++++++++++++++++++++++++
                           |
                      +++++++++++
                      + Cloud 2 +
                      +++++++++++

              Figure 8: Example of Cloud Access Configuration

   As shown in Figure 8, we configure the global VPN to access the
   Internet by creating a cloud-access container pointing to the cloud
   identifier for the Internet service.  (This is illustrated in the XML
   [W3C.REC-xml-20081126] below.)  No authorized sites will be
   configured, as all sites are required to be able to access the
   Internet.

    <?xml version="1.0"?>
       <l2vpn-svc xmlns="urn:ietf:params:xml:ns:yang:ietf-l2vpn-svc">
       <vpn-services>
       <vpn-service>
       <vpn-id>123456487</vpn-id>
      <cloud-accesses>
       <cloud-access>
          <cloud-identifier>INTERNET</cloud-identifier>
       </cloud-access>
      </cloud-accesses>
      <ce-vlan-preservation>true</ce-vlan-preservation>
      <ce-vlan-cos-preservation>true</ce-vlan-cos-preservation>
      </vpn-service>
      </vpn-services>
    </l2vpn-svc>

   If Site 1 and Site 2 require access to Cloud 1, a new cloud-access
   container pointing to the cloud identifier of Cloud 1 will be
   created.  The permit-site leaf-list will be filled with a reference
   to Site 1 and Site 2.

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    <?xml version="1.0"?>
       <l2vpn-svc xmlns="urn:ietf:params:xml:ns:yang:ietf-l2vpn-svc">
        <vpn-services>
         <vpn-service>
         <vpn-id>123456487</vpn-id>
         <cloud-accesses>
          <cloud-access>
            <cloud-identifier>Cloud1</cloud-identifier>
            <permit-site>site1</permit-site>
            <permit-site>site2</permit-site>
          </cloud-access>
         </cloud-accesses>
        <ce-vlan-preservation>true</ce-vlan-preservation>
        <ce-vlan-cos-preservation>true</ce-vlan-cos-preservation>
       </vpn-service>
       </vpn-services>
    </l2vpn-svc>

   If all sites except Site 1 require access to Cloud 2, a new
   cloud-access container pointing to the cloud identifier of Cloud 2
   will be created.  The deny-site leaf-list will be filled with a
   reference to Site 1.

    <?xml version="1.0"?>
      <l2vpn-svc xmlns="urn:ietf:params:xml:ns:yang:ietf-l2vpn-svc">
        <vpn-services>
         <vpn-service>
           <vpn-id>123456487</vpn-id>
            <cloud-accesses>
             <cloud-access>
              <cloud-identifier>Cloud2</cloud-identifier>
              <deny-site>site1</deny-site>
            </cloud-access>
           </cloud-accesses>
          <ce-vlan-preservation>true</ce-vlan-preservation>
          <ce-vlan-cos-preservation>true</ce-vlan-cos-preservation>
        </vpn-service>
      </vpn-services>
    </l2vpn-svc>

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5.2.4.  Extranet VPNs

   There are some cases where a particular VPN needs access to resources
   (servers, hosts, etc.) that are external.  Those resources may be
   located in another VPN.

                 +-----------+           +-----------+
                /             \         /             \
     Site A -- |    VPN A      |  ---  |    VPN B      | --- Site B
                \             /         \             /      (Shared
                 +-----------+           +-----------+        resources)

                 Figure 9: Example of Shared VPN Resources

   As illustrated in Figure 9, VPN B has some resources on Site B that
   need to be made available to some customers/partners.  Specifically,
   VPN A must be able to access those VPN B resources.

   Such a VPN connection scenario can be achieved via a VPN policy as
   defined in Section 5.5.2.2.  But there are some simple cases where a
   particular VPN (VPN A) needs access to all resources in another VPN
   (VPN B).  The model provides an easy way to set up this connection
   using the "extranet-vpns" container.

   The extranet-vpns container defines a list of VPNs a particular VPN
   wants to access.  The extranet-vpns container is used on customer
   VPNs accessing extranet resources in another VPN.  In Figure 9, in
   order to provide VPN A with access to VPN B, the extranet-vpns
   container needs to be configured under VPN A with an entry
   corresponding to VPN B.  There is no service configuration
   requirement on VPN B.

   Readers should note that even if there is no configuration
   requirement on VPN B, if VPN A lists VPN B as an extranet, all sites
   in VPN B will gain access to all sites in VPN A.

   The "site-role" leaf defines the role of the local VPN sites in the
   target extranet VPN service topology.  Site roles are defined in
   Section 5.4.

   In the example below, VPN A accesses VPN B resources through an
   extranet connection.  A Spoke role is required for VPN A sites, as
   sites from VPN A must not be able to communicate with each other
   through the extranet VPN connection.

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     <?xml version="1.0"?>
       <l2vpn-svc xmlns="urn:ietf:params:xml:ns:yang:ietf-l2vpn-svc">
        <vpn-services>
          <vpn-service>
            <vpn-id>VPNB</vpn-id>
              <svc-topo>hub-spoke</svc-topo>
             <ce-vlan-preservation>true</ce-vlan-preservation>
             <ce-vlan-cos-preservation>true</ce-vlan-cos-preservation>
          </vpn-service>
          <vpn-service>
             <vpn-id>VPNA</vpn-id>
               <svc-topo>any-to-any</svc-topo>
                  <extranet-vpns>
                    <extranet-vpn>
                     <vpn-id>VPNB</vpn-id>
                     <local-sites-role>spoke-role</local-sites-role>
                   </extranet-vpn>
                 </extranet-vpns>
             <ce-vlan-preservation>true</ce-vlan-preservation>
             <ce-vlan-cos-preservation>true</ce-vlan-cos-preservation>
         </vpn-service>
       </vpn-services>
      </l2vpn-svc>

   This model does not define how the extranet configuration will be
   achieved within the network.

   Any VPN interconnection scenario that is more complex (e.g., only
   certain parts of sites on VPN A accessing only certain parts of sites
   on VPN B) needs to be achieved using a VPN attachment as defined in
   Section 5.5.2 and, in particular, a VPN policy as defined in
   Section 5.5.2.2.

5.2.5.  Frame Delivery Service

   If a BUM (Broadcast, Unknown Unicast, or Multicast) frame delivery
   service is supported for an L2VPN, some global frame delivery
   parameters are required as input for the service request.  When a CE
   sends BUM packets, replication occurs at the ingress PE and three
   frame types need to be supported.

   Users of this model will need to provide the flavors of trees that
   will be used by customers within the L2VPN (customer-tree-flavors).
   The model defined in this document supports bidirectional, shared,
   and source-based trees (and can be augmented to contain other tree
   types).  Multiple flavors of trees can be supported simultaneously.

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                             Operator network
                              ______________
                             /              \
                            |                |
                            |                |
    Recv -- Site 2 ------- PE2               |
                            |               PE1 --- Site 1 --- Source 1
                            |                |        \
                            |                |         -- Source 2
                            |                |
                            |                |
    Recv -- Site 3 ------- PE3               |
                            |                |
                            |                |
    Recv -- Site 4 ------- PE4               |
                          / |                |
    Recv -- Site 5 -------  |                |
                            |                |
                            |                |
                             \______________/

               Figure 10: BUM Frame Delivery Service Example

   Multicast-group-to-port mappings can be created using the
   "rp-group-mappings" leaf.  Two group-to-port mapping methods are
   supported:

   o  Static configuration of multicast Ethernet addresses and
      ports/interfaces.

   o  A multicast control protocol based on Layer 2 technology that
      signals mappings of multicast addresses to ports/interfaces, such
      as the Generic Attribute Registration Protocol (GARP) / GARP
      Multicast Registration Protocol (GARP/GMRP) [IEEE-802-1D].

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5.3.  Site Overview

   A site represents a connection of a customer office to one or more
   VPN services.  Each site is associated with one or more locations.

                                                    +-------------+
                                                   /               \
                                            +-----|      VPN1       |
     +------------------+                   |      \               /
     |                  |                   |       +-------------+
     |  New York Office |------ (site) -----+
     |                  |                   |       +-------------+
     +------------------+                   |      /               \
                                            +-----|      VPN2       |
                                                   \               /
                                                    +-------------+

         Figure 11: Example: Customer Office and Two VPN Services

   The provider uses the site container to store information regarding
   detailed implementation arrangements made with either the customer or
   peer operators at each interconnect location.

   We restrict the L2SM to exterior interfaces (i.e., UNIs and NNIs)
   only, so all internal interfaces and the underlying topology are
   outside the scope of the L2SM.

   Typically, the following characteristics of a site interface handoff
   need to be documented as part of the service design:

   Unique identifier (site-id):  An arbitrary string to uniquely
      identify the site within the overall network infrastructure.  The
      format of "site-id" is determined by the local administrator of
      the VPN service.

   Device (device):  The customer can request one or more customer
      premises equipment entities from the SP for a particular site.

   Management (management):  Defines the model of management for the
      site -- for example, type, management-transport, address.  This
      parameter determines the boundary between the SP and the customer,
      i.e., who has ownership of the CE device.

   Location (location):  The site location information.  Allows easy
      retrieval of data about the nearest available resources.

   Site diversity (site-diversity):  Presents some parameters to support
      site diversity.

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   Site network accesses (site-network-accesses):  Defines the list of
      ports to the site and their properties -- in particular, bearer,
      connection, and service parameters.

   A site-network-access represents an Ethernet logical connection to a
   site.  A site may have multiple site-network-accesses.

        +------------------+             Site
        |                  |-------------------------------------
        |                  |****** (site-network-access#1) ******
        |  New York Office |
        |                  |****** (site-network-access#2) ******
        |                  |-------------------------------------
        +------------------+

              Figure 12: Two Site-Network-Accesses for a Site

   Multiple site-network-accesses are used, for instance, in the case of
   multihoming.  Some other meshing cases may also include multiple
   site-network-accesses.

   The site configuration is viewed as a global entity; we assume that
   it is mostly the management system's role to split the parameters
   between the different elements within the network.  For example, in
   the case of the site-network-access configuration, the management
   system needs to split the parameters between the PE configuration and
   the CE configuration.

   The site may support single-homed access or multihoming.  In the case
   of multihoming, the site can support multiple site-network-accesses.
   Under each site-network-access, "vpn-attachment" is defined;
   vpn-attachment will describe the association between a given
   site-network-access and a given site, as well as the VPN to which
   that site will connect.

5.3.1.  Devices and Locations

   The information in the "location" sub-container under a site
   container and in the "devices" container allows easy retrieval of
   data about the nearest available facilities and can be used for
   access topology planning.  It may also be used by other network
   orchestration components to choose the targeted upstream PE and
   downstream CE.  Location is expressed in terms of postal information.
   More detailed information or other location information can be added
   by augmentation.

   A site may be composed of multiple locations.  All the locations will
   need to be configured as part of the "locations" container and list.

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   A typical example of a multi-location site is a headquarters office
   in a city, where the office is composed of multiple buildings.  Those
   buildings may be located in different parts of the city and may be
   linked by intra-city fibers (a customer metropolitan area network).
   This model does not represent connectivity between multiple locations
   of a site, because that connectivity is controlled by the customer.
   In such a case, when connecting to a VPN service, the customer may
   ask for multihoming based on its distributed locations.

            New York Site
        +------------------+             Site
        | +--------------+ |-------------------------------------
        | | Manhattan    | |****** (site-network-access#1) ******
        | +--------------+ |
        | +--------------+ |
        | | Brooklyn     | |****** (site-network-access#2) ******
        | +--------------+ |-------------------------------------
        +------------------+

              Figure 13: Two Site-Network-Accesses, Two Sites

   A customer may also request the use of some premises equipment
   entities (CEs) from the SP via the devices container.  Requesting a
   CE implies a provider-managed or co-managed model.  A particular
   device must be requested for a particular already-configured
   location.  This would help the SP send the device to the appropriate
   postal address.  In a multi-location site, a customer may, for
   example, request a CE for each location on the site where multihoming
   must be implemented.  In Figure 13, one device may be requested for
   the Manhattan location and one other for the Brooklyn location.

   By using devices and locations, the user can influence the
   multihoming scenario they want to implement: single CE, dual CE, etc.

5.3.2.  Site Network Accesses

   The L2SM includes a set of essential physical interface properties
   and Ethernet-layer characteristics in the "site-network-accesses"
   container.  Some of these are critical implementation arrangements
   that require consent from both the customer and the provider.

   As mentioned earlier, a site may be multihomed.  Each logical network
   access for a site is defined in the site-network-accesses container.
   The site-network-access parameter defines how the site is connected
   on the network and is split into three main classes of parameters:

   o  bearer: defines requirements of the attachment (below Layer 2).

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   o  connection: defines Layer 2 protocol parameters of the attachment.

   o  availability: defines the site's availability policy.  The
      availability parameters are defined in Section 5.8.

   The site-network-access has a specific type
   (site-network-access type).  This document defines two types:

   o  point-to-point: describes a point-to-point connection between the
      SP and the customer.

   o  multipoint: describes a multipoint connection between the SP and
      the customer.

   This site-network-access type may have an impact on the parameters
   offered to the customer, e.g., an SP might not offer MAC loop
   protection for multipoint accesses.  It is up to the provider to
   decide what parameters are supported for point-to-point and/or
   multipoint accesses.  Multipoint accesses are out of scope for this
   document; some containers defined in the model may require extensions
   in order to work properly for multipoint accesses.

5.3.2.1.  Bearer

   The "bearer" container defines the requirements for the site
   attachment (below Layer 2) to the provider network.

   The bearer parameters will help to determine the access media to
   be used.

5.3.2.2.  Connection

   The "connection" container defines the Layer 2 protocol parameters of
   the attachment (e.g., vlan-id or circuit-id) and provides
   connectivity between customer Ethernet switches.  Depending on the
   management mode, it refers to PE-CE-LAN segment addressing or to
   CE-to-customer-LAN segment addressing.  In any case, it describes the
   responsibility boundary between the provider and the customer.  For a
   customer-managed site, it refers to the PE-CE-LAN segment connection.
   For a provider-managed site, it refers to the CE-to-customer-LAN
   segment connection.

   The "encapsulation-type" parameter allows the user to select between
   Ethernet encapsulation (port-based) or Ethernet VLAN encapsulation
   (VLAN-based).  All of the allowed Ethernet interface types of service
   frames can be listed under "ether-inf-type", e.g., untagged
   interface, tagged interface, LAG interface.

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   Corresponding to "ether-inf-type", the connection container also
   presents three sets of link attributes: untagged interface, tagged
   interface, and optional LAG interface attributes.  These parameters
   are essential for the connection to be properly established between
   the CE devices and the PE devices.  The connection container also
   defines a Layer 2 Control Protocol (L2CP) attribute that allows
   control-plane protocol interaction between the CE devices and the PE
   device.

5.3.2.2.1.  Untagged Interface

   For each untagged interface (untagged-interface), there are basic
   configuration parameters like interface index and speed, interface
   MTU, auto-negotiation and flow-control settings, etc.  In addition,
   and based on mutual agreement, the customer and provider may decide
   to enable advanced features, such as LLDP, IEEE 802.3ah
   [IEEE-802-3ah], or MAC loop detection/prevention at a UNI.  If loop
   avoidance is required, the attribute "uni-loop-prevention" must be
   set to "true".

5.3.2.2.2.  Tagged Interface

   If the tagged service is enabled on a logical unit on the connection
   at the interface, "encapsulation-type" should be specified as the
   Ethernet VLAN encapsulation (if VLAN-based) or VXLAN encapsulation,
   and "eth-inf-type" should be set to indicate a tagged interface.

   In addition, "tagged-interface-type" should be specified in the
   "tagged-interface" container to determine how tagging needs to be
   done.  The current model defines five ways to perform VLAN tagging:

   o  priority-tagged: SPs encapsulate and tag packets between the CE
      and the PE with the frame priority level.

   o  dot1q-vlan-tagged: SPs encapsulate packets between the CE and the
      PE with one or a set of customer VLAN (CVLAN) IDs.

   o  qinq: SPs encapsulate packets that enter their networks with
      multiple CVLAN IDs and a single VLAN tag with a single SP VLAN
      (SVLAN).

   o  qinany: SPs encapsulate packets that enter their networks with
      unknown CVLANs and a single VLAN tag with a single SVLAN.

   o  vxlan: SPs encapsulate packets that enter their networks with a
      VXLAN Network Identifier (VNI) and a peer list.

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   The overall S-tag for the Ethernet circuit and (if applicable)
   C-tag-to-SVC mapping (where "SVC" stands for "Switched Virtual
   Circuit") have been placed in the "service" container.  For the qinq
   and qinany options, the S-tag under "qinq" and "qinany" should match
   the S-tag in the service container in most cases; however, VLAN
   translation is required for the S-tag in certain deployments at the
   external-facing interface or upstream PEs to "normalize" the outer
   VLAN tag to the service S-tag into the network and translate back to
   the site's S-tag in the opposite direction.  One example of this is
   with a Layer 2 aggregation switch along the path: the S-tag for the
   SVC has been previously assigned to another service and thus cannot
   be used by this AC.

5.3.2.2.3.  LAG Interface

   Sometimes, the customer may require multiple physical links bundled
   together to form a single, logical, point-to-point LAG connection to
   the SP.  Typically, the Link Aggregation Control Protocol (LACP) is
   used to dynamically manage adding or deleting member links of the
   aggregate group.  In general, a LAG allows for increased service
   bandwidth beyond the speed of a single physical link while providing
   graceful degradation as failure occurs, thus increasing availability.

   In the L2SM, there is a set of attributes under "lag-interface"
   related to link aggregation functionality.  The customer and provider
   first need to decide on whether LACP PDUs will be exchanged between
   the edge devices by specifying the "LACP-state" as "on" or "off".  If
   LACP is to be enabled, then both parties need to further specify
   (1) whether LACP will be running in active or passive mode and
   (2) the time interval and priority level of the LACP PDU.  The
   customer and provider can also determine the minimum aggregate
   bandwidth for a LAG to be considered as a valid path by specifying
   the optional "mini-link-num" attribute.  To enable fast detection of
   faulty links, micro-BFD [RFC7130] ("BFD" stands for "Bidirectional
   Forwarding Detection") runs independent UDP sessions to monitor the
   status of each member link.  The customer and provider should agree
   on the BFD hello interval and hold time.

   Each member link will be listed under the LAG interface with basic
   physical link properties.  Certain attributes, such as flow control,
   encapsulation type, allowed ingress Ethertype, and LLDP settings, are
   at the LAG level.

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5.3.2.2.4.  CVLAN-ID-to-SVC Mapping

   When more than one service is multiplexed onto the same interface,
   ingress service frames are conditionally transmitted through one of
   the L2VPN services based upon a pre-arranged customer-VLAN-to-SVC
   mapping.  Multiple CVLANs can be bundled across the same SVC.  The
   bundling type will determine how a group of CVLANs is bundled into
   one VPN service (i.e., VLAN-bundling).

   When applicable, "cvlan-id-to-svc-map" contains the list of CVLANs
   that are mapped to the same service.  In most cases, this will be the
   VLAN access-list for the inner 802.1Q tag [IEEE-802-1Q] (the C-tag).

   A VPN service can be set to preserve the CE-VLAN ID and CE-VLAN CoS
   from the source site to the destination site.  This is required when
   the customer wants to use the VLAN header information between its two
   sites.  CE-VLAN ID preservation and CE-VLAN CoS preservation are
   applied on each site-network-access within sites.  "Preservation"
   means that the value of the CE-VLAN ID and/or CE-VLAN CoS at the
   source site must be equal to the value at a destination site
   belonging to the same L2VPN service.

   If all-to-one bundling is enabled (i.e., the bundling type is set to
   "all-to-one bundling"), then preservation applies to all ingress
   service frames.  If all-to-one bundling is disabled, then
   preservation applies to tagged ingress service frames having the
   CE-VLAN ID.

5.3.2.2.5.  L2CP Control Support

   The customer and the SP should arrange in advance whether or not to
   allow control-plane protocol interaction between the CE devices and
   the PE device.  To provide seamless operation with multicast data
   transport, the transparent operation of Ethernet control protocols
   (e.g., the Spanning Tree Protocol (STP) [IEEE-802-1D]) can be
   employed by customers.

   To support efficient dynamic transport, Ethernet multicast control
   frames (e.g., GARP/GMRP [IEEE-802-1D]) can be used between the CE and
   the PE.  However, solutions MUST NOT assume that all CEs are always
   running such protocols (typically in the case where a CE is a router
   and is not aware of Layer 2 details).

   The destination MAC addresses of these L2CP PDUs fall within two
   reserved blocks specified by the IEEE 802.1 Working Group.  Packets
   with destination MAC addresses in these multicast ranges have special
   forwarding rules.

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   o  Bridge block of protocols: 01-80-C2-00-00-00 through
      01-80-C2-00-00-0F

   o  MRP block of protocols: 01-80-C2-00-00-20 through
      01-80-C2-00-00-2F

   Layer 2 protocol tunneling allows SPs to pass subscriber Layer 2
   control PDUs across the network without being interpreted and
   processed by intermediate network devices.  These L2CP PDUs are
   transparently encapsulated across the MPLS-enabled core network in
   QinQ fashion.

   The "L2CP-control" container contains the list of commonly used L2CP
   protocols and parameters.  The SP can specify discard-mode,
   peer-mode, or tunnel-mode actions for each individual protocol.

5.3.2.2.6.  Ethernet Service OAM

   The advent of Ethernet as a wide-area network technology brings the
   additional requirements of end-to-end service monitoring and fault
   management in the SP network, particularly in the area of service
   availability and Mean Time To Repair (MTTR).  Ethernet Service OAM in
   the L2SM refers to the combined protocol suites of IEEE 802.1ag
   [IEEE-802-1ag] and ITU-T Y.1731 [ITU-T-Y-1731].

   Generally speaking, Ethernet Service OAM enables SPs to perform
   service continuity checks, fault isolation, and packet delay/jitter
   measurement at per-customer and per-site-network-access granularity.
   The information collected from Ethernet Service OAM data sets is
   complementary to other higher-layer IP/MPLS OSS tools to ensure that
   the required SLAs can be met.

   The 802.1ag Connectivity Fault Management (CFM) functional model is
   structured with hierarchical Maintenance Domains (MDs), each assigned
   with a unique maintenance level.  Higher-level MDs can be nested over
   lower-level MDs.  However, the MDs cannot intersect.  The scope of
   each MD can be solely within a customer network or solely within the
   SP network.  An MD can interact between CEs and PEs (customer-to-
   provider) or between PEs (provider-to-provider), or it can tunnel
   over another SP network.

   Depending on the use-case scenario, one or more Maintenance Entity
   Group End Points (MEPs) can be placed on the external-facing
   interface, sending CFM PDUs towards the core network ("Up MEP") or
   downstream link ("Down MEP").

   The "cfm-802.1-ag" sub-container under "site-network-access" presents
   the CFM Maintenance Association (MA), i.e., Down MEP for the UNI MA.

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   For each MA, the user can define the Maintenance Association
   Identifier (MAID), MEP level, MEP direction, Remote MEP ID, CoS level
   of the CFM PDUs, Continuity Check Message (CCM) interval and hold
   time, alarm-priority defect (i.e., the lowest-priority defect that is
   allowed to generate a fault alarm), CCM priority type, etc.

   ITU-T Y.1731 Performance Monitoring (PM) provides essential network
   telemetry information that includes the measurement of Ethernet
   service frame delay, frame delay variation, frame loss, and frame
   throughput.  The delay/jitter measurement can be either one-way or
   two-way.  Typically, a Y.1731 PM probe sends a small amount of
   synthetic frames along with service frames to measure the SLA
   parameters.

   The "y-1731" sub-container under "site-network-access" contains a set
   of parameters to define the PM probe information, including MAID,
   local and Remote MEP ID, PM PDU type, message period and measurement
   interval, CoS level of the PM PDUs, loss measurement by synthetic or
   service frame options, one-way or two-way delay measurement, PM frame
   size, and session type.

5.4.  Site Roles

   A VPN has a particular service topology, as described in
   Section 5.2.2.  As a consequence, each site belonging to a VPN is
   assigned a particular role in this topology.  The site-role leaf
   defines the role of the site in a particular VPN topology.

   In the any-to-any VPN service topology, all sites MUST have the same
   role, which will be "any-to-any-role".

   In the Hub-and-Spoke VPN service topology or the Hub-and-Spoke-
   Disjoint VPN service topology, sites MUST have a Hub role or a
   Spoke role.

5.5.  Site Belonging to Multiple VPNs

5.5.1.  Site VPN Flavors

   A site may be part of one or more VPNs.  The "site-vpn-flavor"
   defines the way that the VPN multiplexing is done.  There are four
   possible types of external-facing connections associated with an EVPN
   service and a site.  Therefore, the model supports four flavors:

   o  site-vpn-flavor-single: The site belongs to only one VPN.

   o  site-vpn-flavor-multi: The site belongs to multiple VPNs, and all
      the logical accesses of the sites belong to the same set of VPNs.

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   o  site-vpn-flavor-nni: The site represents an NNI where two
      administrative domains belonging to the same or different
      providers interconnect.

   o  site-vpn-flavor-e2e: The site represents an end-to-end
      multi-segment connection.

5.5.1.1.  Single VPN Attachment: site-vpn-flavor-single

   Figure 14 depicts a single VPN attachment.  The site connects to only
   one VPN.

                                                         +--------+
      +------------------+             Site             /          \
      |                  |-----------------------------|            |
      |                  |***(site-network-access#1)***|    VPN1    |
      |  New York Office |                             |            |
      |                  |***(site-network-access#2)***|            |
      |                  |-----------------------------|            |
      +------------------+                              \          /
                                                         +--------+

                     Figure 14: Single VPN Attachment

5.5.1.2.  Multi-VPN Attachment: site-vpn-flavor-multi

   Figure 15 shows a site connected to multiple VPNs.

                                                           +---------+
                                                      +---/----+      \
   +------------------+             Site             /   |      \      |
   |                  |--------------------------------- |       |VPN B|
   |                  |***(site-network-access#1)******* |       |     |
   |  New York Office |                             |    |       |     |
   |                  |***(site-network-access#2)*******  \      |    /
   |                  |-----------------------------| VPN A+-----|---+
   +------------------+                              \          /
                                                      +--------+

                      Figure 15: Multi-VPN Attachment

   In Figure 15, the New York office is multihomed.  Both logical
   accesses are using the same VPN attachment rules, and both are
   connected to VPN A and to VPN B.

   Reaching VPN A or VPN B from the New York office will be done via MAC
   destination-based forwarding.  Having the same destination reachable
   from the two VPNs may cause routing problems.  The customer

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   administration's role in this case would be to ensure the appropriate
   mapping of its MAC addresses in each VPN.  See Sections 5.5.2 and
   5.10.2 for more details.  See also Section 5.10.3 for details
   regarding support for BUM.

5.5.1.3.  NNI: site-vpn-flavor-nni

   A Network-to-Network Interface (NNI) scenario may be modeled using
   the sites container.  It is helpful for the SP to indicate that the
   requested VPN connection is not a regular site but rather is an NNI,
   as specific default device configuration parameters may be applied in
   the case of NNIs (e.g., Access Control Lists (ACLs), routing
   policies).

             SP A                                         SP B
      -------------------                         -------------------
     /                   \                       /                   \
    |                     |                     |                     |
    |                 ++++++++ Inter-AS link ++++++++                 |
    |                 +      +_______________+      +                 |
    |                 + (MAC-VRF1)-(VPN1)-(MAC-VRF1)+                 |
    |                 +      +               +      +                 |
    |                 + ASBR +               + ASBR +                 |
    |                 +      +               +      +                 |
    |                 + (MAC-VRF2)-(VPN2)-(MAC-VRF2)+                 |
    |                 +      +_______________+      +                 |
    |                 ++++++++               ++++++++                 |
    |                     |                     |                     |
    |                     |                     |                     |
    |                     |                     |                     |
    |                 ++++++++ Inter-AS link ++++++++                 |
    |                 +      +_______________+      +                 |
    |                 + (MAC-VRF1)-(VPN1)-(MAC-VRF1)+                 |
    |                 +      +               +      +                 |
    |                 + ASBR +               + ASBR +                 |
    |                 +      +               +      +                 |
    |                 + (MAC-VRF2)-(VPN2)-(MAC-VRF2)+                 |
    |                 +      +_______________+      +                 |
    |                 ++++++++               ++++++++                 |
    |                     |                     |                     |
    |                     |                     |                     |
     \                   /                       \                   /
      -------------------                         -------------------

                     Figure 16: Option A NNI Scenario

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   Figure 16 illustrates an option A NNI scenario that can be modeled
   using the sites container.  In order to connect its customer VPNs
   (VPN1 and VPN2) in SP B, SP A may request the creation of some
   site-network-accesses to SP B.  The site-vpn-flavor-nni type will
   be used to inform SP B that this is an NNI and not a regular
   customer site.

5.5.1.4.  E2E: site-vpn-flavor-e2e

   An end-to-end (E2E) multi-segment VPN connection to be constructed
   out of several connectivity segments may be modeled.  It is helpful
   for the SP to indicate that the requested VPN connection is not a
   regular site but rather is an end-to-end VPN connection, as specific
   default device configuration parameters may be applied in the case of
   site-vpn-flavor-e2e (e.g., QoS configuration).  In order to establish
   a connection between Site 1 in SP A and Site 2 in SP B spanning
   multiple domains, SP A may request the creation of end-to-end
   connectivity to SP B.  The site-vpn-flavor-e2e type will be used to
   indicate that this is an end-to-end connectivity setup and not a
   regular customer site.

5.5.2.  Attaching a Site to a VPN

   Due to the multiple site-vpn flavors, the attachment of a site to an
   L2VPN is done at the site-network-access (logical access) level
   through the "vpn-attachment" container.  The vpn-attachment container
   is mandatory.  The model provides two ways to attach a site to a VPN:

   o  By referencing the target VPN directly.

   o  By referencing a VPN policy for attachments that are more complex.

   These options allow the user to choose the flavor that provides the
   best fit.

5.5.2.1.  Referencing a VPN

   Referencing a vpn-id provides an easy way to attach a particular
   logical access to a VPN.  This is the best way in the case of a
   single VPN attachment.  When referencing a vpn-id, the site-role
   setting must be added to express the role of the site in the target
   VPN service topology.

    <?xml version="1.0"?>
    <l2vpn-svc xmlns="urn:ietf:params:xml:ns:yang:ietf-l2vpn-svc">
     <vpn-services>
        <vpn-service>
          <vpn-id>VPNA</vpn-id>

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          <ce-vlan-preservation>true</ce-vlan-preservation>
          <ce-vlan-cos-preservation>true</ce-vlan-cos-preservation>
        </vpn-service>
        <vpn-service>
          <vpn-id>VPNB</vpn-id>
          <ce-vlan-preservation>true</ce-vlan-preservation>
          <ce-vlan-cos-preservation>true</ce-vlan-cos-preservation>
        </vpn-service>
     </vpn-services>
     <sites>
       <site>
        <site-id>SITE1</site-id>
       <locations>
        <location>
         <location-id>L1</location-id>
        </location>
       </locations>
       <management>
        <type>customer-managed</type>
          </management>
           <site-network-accesses>
            <site-network-access>
             <network-access-id>LA1</network-access-id>
                <service>
                  <svc-bandwidth>
                     <bandwidth>
                       <direction>input-bw</direction>
                        <type>bw-per-cos</type>
                         <cir>450000000</cir>
                         <cbs>20000000</cbs>
                         <eir>1000000000</eir>
                         <ebs>200000000</ebs>
                     </bandwidth>
                    </svc-bandwidth>
                     <carrierscarrier>
                       <signaling-type>bgp</signaling-type>
                     </carrierscarrier>
                     <svc-mtu>1514</svc-mtu>
                   </service>
            <vpn-attachment>
             <vpn-id>VPNA</vpn-id>
             <site-role>spoke-role</site-role>
            </vpn-attachment>
           </site-network-access>
           <site-network-access>
            <network-access-id>LA2</network-access-id>
                <service>
                  <svc-bandwidth>

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                     <bandwidth>
                       <direction>input-bw</direction>
                        <type>bw-per-cos</type>
                         <cir>450000000</cir>
                         <cbs>20000000</cbs>
                         <eir>1000000000</eir>
                         <ebs>200000000</ebs>
                     </bandwidth>
                    </svc-bandwidth>
                     <carrierscarrier>
                       <signaling-type>bgp</signaling-type>
                     </carrierscarrier>
                     <svc-mtu>1514</svc-mtu>
                   </service>
            <vpn-attachment>
             <vpn-id>VPNB</vpn-id>
             <site-role>spoke-role</site-role>
            </vpn-attachment>
           </site-network-access>
          </site-network-accesses>
      </site>
     </sites>
    </l2vpn-svc>

   The example above describes a multi-VPN case where a site (SITE 1)
   has two logical accesses (LA1 and LA2), attached to both VPNA and
   VPNB.

5.5.2.2.  VPN Policy

   The "vpn-policy" list helps express a multi-VPN scenario where a
   logical access belongs to multiple VPNs.

   As a site can belong to multiple VPNs, the vpn-policy list may be
   composed of multiple entries.  A filter can be applied to specify
   that only some LANs at the site should be part of a particular VPN.
   A site can be composed of multiple LAN segments, and each LAN segment
   can be connected to a different VPN.  Each time a site (or LAN) is
   attached to a VPN, the user must precisely describe its role
   (site-role) within the target VPN service topology.

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     +---------------------------------------------------------------+
     |       Site 1 ------ PE7                                       |
     +-------------------------+                 [VPN2]              |
                               |                                     |
     +-------------------------+                                     |
     |       Site 2 ------ PE3               PE4 ------ Site 3       |
     +-----------------------------------+                           |
                                         |                           |
     +-------------------------------------------------------------+ |
     |       Site 4 ------ PE5           |   PE6 ------ Site 5     | |
     |                                                             | |
     |                      [VPN3]                                 | |
     +-------------------------------------------------------------+ |
                                        |                            |
                                        +----------------------------+

                       Figure 17: VPN Policy Example

   In Figure 17, Site 5 is part of two VPNs: VPN3 and VPN2.  It will
   play a Hub role in VPN2 and an any-to-any role in VPN3.  We can
   express such a multi-VPN scenario as follows:

   <?xml version="1.0"?>
    <l2vpn-svc xmlns="urn:ietf:params:xml:ns:yang:ietf-l2vpn-svc">
     <vpn-services>
      <vpn-service>
       <vpn-id>VPN2</vpn-id>
       <ce-vlan-preservation>true</ce-vlan-preservation>
       <ce-vlan-cos-preservation>true</ce-vlan-cos-preservation>
      </vpn-service>
      <vpn-service>
       <vpn-id>VPN3</vpn-id>
       <ce-vlan-preservation>true</ce-vlan-preservation>
       <ce-vlan-cos-preservation>true</ce-vlan-cos-preservation>
      </vpn-service>
     </vpn-services>
     <sites>
        <site>
       <locations>
        <location>
         <location-id>L1</location-id>
        </location>
       </locations>
       <management>
        <type>customer-managed</type>
       </management>
          <site-id>Site5</site-id>
          <vpn-policies>

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           <vpn-policy>
            <vpn-policy-id>POLICY1</vpn-policy-id>
            <entries>
             <id>ENTRY1</id>
             <vpn>
              <vpn-id>VPN2</vpn-id>
              <site-role>hub-role</site-role>
             </vpn>
            </entries>
            <entries>
             <id>ENTRY2</id>
             <vpn>
              <vpn-id>VPN3</vpn-id>
              <site-role>any-to-any-role</site-role>
             </vpn>
            </entries>
           </vpn-policy>
          </vpn-policies>
          <site-network-accesses>
           <site-network-access>
            <network-access-id>LA1</network-access-id>
         <site>
          <site-id>SITE1</site-id>
       <locations>
        <location>
         <location-id>L1</location-id>
        </location>
       </locations>
       <management>
        <type>customer-managed</type>
       </management>
          <site-network-accesses>
           <site-network-access>
            <network-access-id>LA1</network-access-id>
                <service>
                  <svc-bandwidth>
                     <bandwidth>
                       <direction>input-bw</direction>
                        <type>bw-per-cos</type>
                         <cir>450000000</cir>
                         <cbs>20000000</cbs>
                         <eir>1000000000</eir>
                         <ebs>200000000</ebs>
                     </bandwidth>
                    </svc-bandwidth>
                     <carrierscarrier>
                       <signaling-type>bgp</signaling-type>
                     </carrierscarrier>

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                     <svc-mtu>1514</svc-mtu>
                   </service>
            <vpn-attachment>
             <vpn-id>VPNA</vpn-id>
             <site-role>spoke-role</site-role>
            </vpn-attachment>
           </site-network-access>
           <site-network-access>
            <network-access-id>LA2</network-access-id>
                <service>
                  <svc-bandwidth>
                     <bandwidth>
                       <direction>input-bw</direction>
                        <type>bw-per-cos</type>
                         <cir>450000000</cir>
                         <cbs>20000000</cbs>
                         <eir>1000000000</eir>
                         <ebs>200000000</ebs>
                     </bandwidth>
                    </svc-bandwidth>
                     <carrierscarrier>
                       <signaling-type>bgp</signaling-type>
                     </carrierscarrier>
                     <svc-mtu>1514</svc-mtu>
                   </service>
            <vpn-attachment>
             <vpn-id>VPNB</vpn-id>
             <site-role>spoke-role</site-role>
            </vpn-attachment>
           </site-network-access>
          </site-network-accesses>
         </site>
            <vpn-attachment>
             <vpn-policy-id>POLICY1</vpn-policy-id>
            </vpn-attachment>
           </site-network-access>
          </site-network-accesses>
         </site>
     </sites>
    </l2vpn-svc>

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   Now, if a more granular VPN attachment is necessary, filtering can be
   used.  For example, if LAN1 from Site 5 must be attached to VPN2 as a
   Hub and LAN2 must be attached to VPN3, the following configuration
   can be used:

    <?xml version="1.0"?>
      <l2vpn-svc xmlns="urn:ietf:params:xml:ns:yang:ietf-l2vpn-svc">
        <vpn-services>
          <vpn-service>
            <vpn-id>VPN2</vpn-id>
            <ce-vlan-preservation>true</ce-vlan-preservation>
            <ce-vlan-cos-preservation>true</ce-vlan-cos-preservation>
            </vpn-service>
            <vpn-service>
             <vpn-id>VPN3</vpn-id>
             <ce-vlan-preservation>true</ce-vlan-preservation>
             <ce-vlan-cos-preservation>true</ce-vlan-cos-preservation>
            </vpn-service>
        </vpn-services>
      <sites>
       <site>
       <locations>
        <location>
         <location-id>L1</location-id>
        </location>
       </locations>
       <management>
        <type>customer-managed</type>
       </management>
             <site-id>Site5</site-id>
             <vpn-policies>
              <vpn-policy>
               <vpn-policy-id>POLICY1</vpn-policy-id>
               <entries>
                <id>ENTRY1</id>
                <filters>
                  <filter>
                    <type>lan</type>
                    <lan-tag>LAN1</lan-tag>
                  </filter>
                </filters>
                <vpn>
                 <vpn-id>VPN2</vpn-id>
                 <site-role>hub-role</site-role>
                </vpn>
               </entries>
               <entries>
                <id>ENTRY2</id>

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                <filters>
                  <filter>
                    <type>lan</type>
                    <lan-tag>LAN2</lan-tag>
                  </filter>
                </filters>
                 <vpn>
                 <vpn-id>VPN3</vpn-id>
                 <site-role>any-to-any-role</site-role>
                </vpn>
               </entries>
              </vpn-policy>
             </vpn-policies>
             <site-network-accesses>
              <site-network-access>
               <network-access-id>LA1</network-access-id>
                 <service>
                   <svc-bandwidth>
                      <bandwidth>
                       <direction>input-bw</direction>
                        <type>bw-per-cos</type>
                         <cir>450000000</cir>
                         <cbs>20000000</cbs>
                         <eir>1000000000</eir>
                         <ebs>200000000</ebs>
                      </bandwidth>
                     </svc-bandwidth>
                      <carrierscarrier>
                         <signaling-type>bgp</signaling-type>
                      </carrierscarrier>
                       <svc-mtu>1514</svc-mtu>
                   </service>
               <vpn-attachment>
                <vpn-policy-id>POLICY1</vpn-policy-id>
               </vpn-attachment>
              </site-network-access>
             </site-network-accesses>
            </site>
           </sites>
         </l2vpn-svc>

5.6.  Deciding Where to Connect the Site

   The management system will have to determine where to connect each
   site-network-access of a particular site to the provider network
   (e.g., PE or aggregation switch).

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   This model defines parameters and constraints that can influence the
   meshing of the site-network-access.

   The management system MUST honor all customer constraints, or, if a
   constraint is too strict and cannot be fulfilled, the management
   system MUST NOT provision the site and MUST provide the user with
   information regarding any constraints that could not be fulfilled.
   How this information is provided is out of scope for this document.
   Whether or not to relax the constraint would then be left up to
   the user.

   Parameters such as site location (see Section 5.6.2) and access type
   (see Section 5.6.3) affect the service placement that the management
   system applies.

   In addition to parameters and constraints, the management system's
   decision MAY be based on any other internal constraints that are left
   up to the SP, e.g., least load, distance.

5.6.1.  Constraint: Device

   In the case of provider management or co-management, one or more
   devices have been ordered by the customer to a particular location
   that has already been configured.  The customer may force a
   particular site-network-access to be connected on a particular device
   that it ordered.

             New York Site
        +------------------+             Site
        | +--------------+ |-------------------------------------
        | | Manhattan    | |
        | |           CE1********* (site-network-access#1) ******
        | +--------------+ |
        | +--------------+ |
        | | Brooklyn     | |
        | |           CE2********* (site-network-access#2) ******
        | +--------------+ |
        |                  |-------------------------------------
        +------------------+

          Figure 18: Example of a Constraint Applied to a Device

   In Figure 18, site-network-access#1 is associated with CE1 in the
   service request.  The SP must ensure the provisioning of this
   connection.

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5.6.2.  Constraint/Parameter: Site Location

   The location information provided in this model MAY be used by a
   management system to determine the target PE to mesh the site (SP
   side).  A particular location must be associated with each site
   network access when configuring it.  The SP MUST honor the
   termination of the access on the location associated with the site
   network access (customer side).  The "country-code" in the site
   location should be expressed as an ISO 3166 code and is similar to
   the "country" label defined in [RFC4119].

   The site-network-access location is determined by the
   "location-flavor".  In the case of a provider-managed or co-managed
   site, the user is expected to configure a "device-reference" (device
   case) that will bind the site-network-access to a particular device
   that the customer ordered.  As each device is already associated with
   a particular location, in such a case the location information is
   retrieved from the device location.  In the case of a
   customer-managed site, the user is expected to configure a
   "location-reference" (location case); this provides a reference to an
   existing configured location and will help with placement.

                                         POP#1 (New York)
                                      +---------+
                                      |   PE1   |
                 Site 1 ---...        |   PE2   |
                (Atlantic City)       |   PE3   |
                                      +---------+

                                         POP#2 (Washington)
                                      +---------+
                                      |   PE4   |
                                      |   PE5   |
                                      |   PE6   |
                                      +---------+

                                         POP#3 (Philadelphia)
                                      +---------+
                                      |   PE7   |
                 Site 2 CE#1---...    |   PE8   |
                (Reston)              |   PE9   |
                                      +---------+

                 Figure 19: Location Information for Sites

   In Figure 19, Site 1 is a customer-managed site with a location "L1",
   while Site 2 is a provider-managed site for which a CE (CE#1) was
   ordered.  Site 2 is configured with "L2" as its location.  When

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   configuring a site-network-access for Site 1, the user will need to
   reference location L1 so that the management system will know that
   the access will need to terminate on this location.  Then, for
   distance reasons, this management system may mesh Site 1 on a PE in
   the Philadelphia POP.  It may also take into account resources
   available on PEs to determine the exact target PE (e.g., least
   loaded).  For Site 2, the user is expected to configure the
   site-network-access with a device-reference to CE#1 so that the
   management system will know that the access must terminate on the
   location of CE#1 and must be connected to CE#1.  For placement of the
   SP side of the access connection, in the case of the nearest PE used,
   it may mesh Site 2 on the Washington POP.

5.6.3.  Constraint/Parameter: Access Type

   The management system needs to elect the access media to connect the
   site to the customer (for example, xDSL, leased line, Ethernet
   backhaul).  The customer may provide some parameters/constraints that
   will provide hints to the management system.

   The bearer container information SHOULD be the first piece of
   information considered when making this decision:

   o  The "requested-type" parameter provides information about the
      media type that the customer would like to use.  If the "strict"
      leaf is equal to "true", this MUST be considered a strict
      constraint so that the management system cannot connect the site
      with another media type.  If the "strict" leaf is equal to "false"
      (default) and if the requested media type cannot be fulfilled, the
      management system can select another media type.  The supported
      media types SHOULD be communicated by the SP to the customer via a
      mechanism that is out of scope for this document.

   o  The "always-on" leaf defines a strict constraint: if set to
      "true", the management system MUST elect a media type that is
      "always-on" (e.g., this means no dial-in access type).

   o  The "bearer-reference" parameter is used in cases where the
      customer has already ordered a network connection to the SP apart
      from the L2VPN site and wants to reuse this connection.  The
      string used is an internal reference from the SP and describes the
      already-available connection.  This is also a strict requirement
      that cannot be relaxed.  How the reference is given to the
      customer is out of scope for this document, but as an example,
      when the customer ordered the bearer (through a process that is
      out of scope for this model), the SP may have provided the bearer
      reference that can be used for provisioning services on top.

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   Any other internal parameters from the SP can also be used.  The
   management system MAY use other parameters, such as the requested
   "input svc-bandwidth" and "output svc-bandwidth", to help decide
   which access type to use.

5.6.4.  Constraint: Access Diversity

   Each site-network-access may have one or more constraints that would
   drive the placement of the access.  By default, the model assumes
   that there are no constraints, but allocation of a unique bearer per
   site-network-access is expected.

   In order to help with the different placement scenarios, a
   site-network-access may be tagged using one or multiple group
   identifiers.  The group identifier is a string, so it can accommodate
   both explicit naming of a group of sites (e.g., "multihomed-set1")
   and the use of a numbered identifier (e.g., 12345678).  The meaning
   of each group-id is local to each customer administrator, and the
   management system MUST ensure that different customers can use the
   same group-ids.  One or more group-ids can also be defined at the
   site level; as a consequence, all site-network-accesses under the
   site MUST inherit the group-ids of the site to which they belong.
   When, in addition to the site group-ids some group-ids are defined at
   the site-network-access level, the management system MUST consider
   the union of all groups (site level and site-network-access level)
   for this particular site-network-access.

   For an already-configured site-network-access, each constraint MUST
   be expressed against a targeted set of site-network-accesses.  This
   site-network-access (i.e., the already-configured
   site-network-access) MUST never be taken into account in the targeted
   set of site-network-accesses -- for example, "My site-network-access
   S must not be connected on the same POP as the site-network-accesses
   that are part of Group 10."  The set of site-network-accesses against
   which the constraint is evaluated can be expressed as a list of
   groups, "all-other-accesses", or "all-other-groups".  The
   all-other-accesses option means that the current site-network-access
   constraint MUST be evaluated against all the other
   site-network-accesses belonging to the current site.  The
   all-other-groups option means that the constraint MUST be evaluated
   against all groups to which the current site-network-access does not
   belong.

   The current model defines multiple constraint-types:

   o  pe-diverse: The current site-network-access MUST NOT be connected
      to the same PE as the targeted site-network-accesses.

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   o  pop-diverse: The current site-network-access MUST NOT be connected
      to the same POP as the targeted site-network-accesses.

   o  linecard-diverse: The current site-network-access MUST NOT be
      connected to the same linecard as the targeted site-network-
      accesses.  Note that the customer can request linecard-diverse for
      site-network-accesses, but the specific linecard identifier used
      should not be exposed to the customer.

   o  bearer-diverse: The current site-network-access MUST NOT use
      common bearer components compared to bearers used by the targeted
      site-network-accesses.  "bearer-diverse" provides some level of
      diversity at the access level.  As an example, two bearer-diverse
      site-network-accesses must not use the same Digital Subscriber
      Line Access Multiplexer (DSLAM), Broadband Access Switch (BAS), or
      Layer 2 switch.

   o  same-pe: The current site-network-access MUST be connected to the
      same PE as the targeted site-network-accesses.

   o  same-bearer: The current site-network-access MUST be connected
      using the same bearer as the targeted site-network-accesses.

   These constraint-types can be extended through augmentation.  Each
   constraint is expressed as "The site-network-access S must be
   <constraint-type> (e.g., pe-diverse, pop-diverse) from these <target>
   site-network-accesses."

   The group-id used to target some site-network-accesses may be the
   same as the one used by the current site-network-access.  This eases
   the configuration of scenarios where a group of site-network-access
   points has a constraint between the access points in the group.

5.7.  Route Distinguisher and Network Instance Allocation

   The Route Distinguisher (RD) is a critical parameter of BGP-based
   L2VPNs as described in [RFC4364] that provides the ability to
   distinguish common addressing plans in different VPNs.  As for Route
   Targets (RTs), a management system is expected to allocate a MAC-VRF
   on the target PE and an RD for that MAC-VRF; that RD MUST be unique
   across all MAC-VRFs on the target PE.

   If a MAC-VRF already exists on the target PE and the MAC-VRF fulfills
   the connectivity constraints for the site, there is no need to
   recreate another MAC-VRF, and the site MAY be meshed within the
   existing MAC-VRF.  How the management system checks to see if an
   existing MAC-VRF fulfills the connectivity constraints for a site is
   out of scope for this document.

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   If no such MAC-VRF exists on the target PE, the management system has
   to initiate the creation of a new MAC-VRF on the target PE and has to
   allocate a new RD for the new MAC-VRF.

   The management system MAY apply a per-VPN or per-MAC-VRF allocation
   policy for the RD, depending on the SP's policy.  In a per-VPN
   allocation policy, all MAC-VRFs (dispatched on multiple PEs) within a
   VPN will share the same RD value.  In a per-MAC-VRF model, all
   MAC-VRFs should always have a unique RD value.  Some other allocation
   policies are also possible, and this document does not restrict the
   allocation policies to be used.

   The allocation of RDs MAY be done in the same way as RTs.  The
   information provided in Section 5.2.2.1 could also be used in this
   scenario.

   Note that an SP MAY configure a target PE for an automated allocation
   of RDs.  In this case, there will be no need for any backend system
   to allocate an RD value.

5.8.  Site-Network-Access Availability

   A site may be multihomed, meaning that it has multiple
   site-network-access points.  The placement constraints defined in
   Section 5.6 will help ensure physical diversity.

   When the site-network-accesses are placed on the network, a customer
   may want to use a particular routing policy on those accesses.  The
   "site-network-access/availability" container defines parameters for
   site redundancy.  The "access-priority" leaf defines a preference for
   a particular access.  This preference is used to model load-balancing
   or primary/backup scenarios.  The higher the access-priority value,
   the higher the preference will be.  The "redundancy-mode" attribute
   is defined for a multihoming site and used to model single-active and
   active/active scenarios.  It allows for multiple active paths in
   forwarding state and for load-balancing options.

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   Figure 20 illustrates how the access-priority attribute can be used.

        Hub#1 LAN (Primary/backup)          Hub#2 LAN (Load-sharing)
          |                                                     |
          |    access-priority 1          access-priority 1     |
          |--- CE1 ------- PE1            PE3 --------- CE3 --- |
          |                                                     |
          |                                                     |
          |--- CE2 ------- PE2            PE4 --------- CE4 --- |
          |    access-priority 2          access-priority 1     |

                                  PE5
                                   |
                                   |
                                   |
                                  CE5
                                   |
                              Spoke#1 site (Single-homed)

              Figure 20: Example: Configuring Access Priority

   In Figure 20, Hub#2 requires load-sharing, so all the site-network-
   accesses must use the same access-priority value.  On the other hand,
   as Hub#1 requires a primary site-network-access and a backup
   site-network-access, a higher access-priority setting will be
   configured on the primary site-network-access.

   Scenarios that are more complex can also be modeled.  Let's consider
   a Hub site with five accesses to the network (A1, A2, A3, A4, and
   A5).  The customer wants to load-share its traffic on A1 and A2 in
   the nominal situation.  If A1 and A2 fail, the customer wants to
   load-share its traffic on A3 and A4; finally, if A1, A2, A3, and A4
   are all down, the customer wants to use A5.  We can model this easily
   by configuring the following access-priority values: A1=100, A2=100,
   A3=50, A4=50, A5=10.

   The access-priority scenario has some limitations.  An
   access-priority scenario like the previous one with five accesses but
   with the constraint of having traffic load-shared between A3 and A4
   in the case where only A1 or A2 (not both) is down is not achievable.
   But the access-priority attribute defined will cover most of the
   deployment use cases, and if necessary the model can be extended via
   augmentation to support additional use cases.

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5.9.  SVC MTU

   The MTU of subscriber service frames can be derived from the physical
   interface MTU by default, or it can be specified under the "svc-mtu"
   leaf if it is different than the default number.

5.10.  Service

   The service container defines service parameters associated with
   the site.

5.10.1.  Bandwidth

   The service bandwidth refers to the bandwidth requirement between the
   CE and the PE and can be represented using the Committed Information
   Rate (CIR), the Excess Information Rate (EIR), or the Peak
   Information Rate (PIR).  The requested bandwidth is expressed as
   ingress bandwidth and egress bandwidth.  The ingress or egress
   direction uses the customer site as the point of reference:
   "ingress-direction bandwidth" refers to download bandwidth for the
   site, and "egress-direction bandwidth" refers to upload bandwidth for
   the site.

   The service bandwidth is only configurable at the site-network-access
   level (i.e., for the site network access associated with the site).

   Using a different ingress and egress bandwidth will allow an SP to
   know if a customer allows for asymmetric bandwidth access like ADSL.
   It can also be used to set the rate limit in a different way for
   uploads and downloads on symmetric bandwidth access.

   The svc-bandwidth parameter has a specific type.  This document
   defines four types:

   o  bw-per-access: bandwidth is per connection or site network access,
      providing rate enforcement for all service frames at the interface
      that are associated with a particular network access.

   o  bw-per-cos: bandwidth is per CoS, providing rate enforcement for
      all service frames for a given CoS with a specific cos-id.

   o  bw-per-svc: bandwidth is per site, providing rate enforcement for
      all service frames that are associated with a particular VPN
      service.

   o  opaque bandwidth is the total bandwidth that is not associated
      with any particular cos-id, VPN service identified with the
      vpn-id, or site network access ID.

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   The svc-bandwidth parameter must include a "cos-id" parameter if the
   "type" is set to "bw-per-cos".  The cos-id can be assigned based on
   either (1) the IEEE 802.1p value [IEEE-802-1D] in the C-tag or
   (2) the Differentiated Services Code Point (DSCP) in the Ethernet
   frame header.  Service frames are metered against the bandwidth
   profile based on the cos-id.

   The svc-bandwidth parameter must be associated with a specific
   "site-network-access-id" parameter if the "type" is set to
   "bw-per-access".  Multiple bandwidths per cos-id can be associated
   with the same site network access.

   The svc-bandwidth parameter must include a specific "vpn-id"
   parameter if the "type" is set to "bw-per-svc".  Multiple bandwidths
   per cos-id can be associated with the same EVPN service.

5.10.2.  QoS

   The model defines QoS parameters as an abstraction:

   o  qos-classification-policy: Defines a set of ordered rules to
      classify customer traffic.

   o  qos-profile: Provides a QoS scheduling profile to be applied.

5.10.2.1.  QoS Classification

   QoS classification rules are handled by "qos-classification-policy".
   qos-classification-policy is an ordered list of rules that match a
   flow or application and set the appropriate target CoS
   (target-class-id).  The user can define the match using a
   more specific flow definition (based on Layer 2 source and
   destination MAC addresses, cos, dscp, cos-id, color-id, etc.).  A
   "color-id" will be assigned to a service frame to identify its QoS
   profile conformance.  A service frame is "green" if it is conformant
   with the "committed" rate of the bandwidth profile.  A service frame
   is "yellow" if it exceeds the "committed" rate but is conformant with
   the "excess" rate of the bandwidth profile.  Finally, a service frame
   is "red" if it is conformant with neither the "committed" rate nor
   the "excess" rate of the bandwidth profile.

   When a flow definition is used, the user can use a target-sites
   leaf-list to identify the destination of a flow rather than using
   destination addresses.  In such a case, an association between the
   site abstraction and the MAC addresses used by this site must be done
   dynamically.  How this association is done is out of scope for this
   document.  The association of a site to an L2VPN is done through the
   vpn-attachment container.  Therefore, the user can also employ the

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   "target-sites" leaf-list and "vpn-attachment" to identify the
   destination of a flow targeted to a specific VPN service.  A rule
   that does not have a "match" statement is considered a "match-all"
   rule.  An SP may implement a default terminal classification rule if
   the customer does not provide it.  It will be up to the SP to
   determine its default target class.  This model defines some
   applications, but new application identities may be added through
   augmentation.  The exact meaning of each application identity is up
   to the SP, so it will be necessary for the SP to advise the customer
   on the usage of application-matching.

5.10.2.2.  QoS Profile

   A user can choose between the standard profile provided by the
   operator or a custom profile.  The QoS profile ("qos-profile")
   defines the traffic-scheduling policy to be used by the SP.

   A custom QoS profile is defined as a list of CoS entries and
   associated properties.  The properties are as follows:

   o  direction: Used to specify the direction to which the qos-profile
      setting is applied.  This model supports the site-to-WAN direction
      ("site-to-wan"), the WAN-to-site direction ("wan-to-site"), and
      both directions ("bidirectional").  By default, "bidirectional" is
      used.  In the case of both directions, the provider should ensure
      scheduling according to the requested policy in both traffic
      directions (SP to customer and customer to SP).  As an example, a
      device-scheduling policy may be implemented on both the PE side
      and the CE side of the WAN link.  In the case of the WAN-to-site
      direction, the provider should ensure scheduling from the SP
      network to the customer site.  As an example, a device-scheduling
      policy may be implemented only on the PE side of the WAN link
      towards the customer.

   o  policing: Optional.  Indicates whether policing should apply to
      one-rate, two-color or to two-rate, three-color.

   o  byte-offset: Optional.  Indicates how many bytes in the service
      frame header are excluded from rate enforcement.

   o  frame-delay: Used to define the latency constraint of the class.
      The latency constraint can be expressed as the lowest possible
      latency or as a latency boundary expressed in milliseconds.  How
      this latency constraint will be fulfilled is up to the SP
      implementation: a strict priority-queuing mechanism may be used on
      the access and in the core network, or a low-latency routing path
      may be created for this traffic class.

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   o  frame-jitter: Used to define the jitter constraint of the class.
      The jitter constraint can be expressed as the lowest possible
      jitter or as a jitter boundary expressed in microseconds.  How
      this jitter constraint will be fulfilled is up to the SP
      implementation: a strict priority-queuing mechanism may be used on
      the access and in the core network, or a jitter-aware routing path
      may be created for this traffic class.

   o  bandwidth: Used to define a guaranteed amount of bandwidth for
      the CoS.  It is expressed as a percentage.  The
      "guaranteed-bw-percent" parameter uses available bandwidth as a
      reference.  The available bandwidth should not fall below the CIR
      value defined under the input svc-bandwidth or the output
      svc-bandwidth.  When the "qos-profile" container is implemented on
      the CE side, the output svc-bandwidth is taken into account as a
      reference.  When it is implemented on the PE side, the input
      svc-bandwidth is used.  By default, the bandwidth reservation is
      only guaranteed at the access level.  The user can use the
      "end-to-end" leaf to request an end-to-end bandwidth reservation,
      including across the MPLS transport network.  (In other words, the
      SP will activate something in the MPLS core to ensure that the
      bandwidth request from the customer will be fulfilled by the MPLS
      core as well.)  How this is done (e.g., RSVP-TE reservation,
      controller reservation) is out of scope for this document.

   In addition, due to network conditions, some constraints may not be
   completely fulfilled by the SP; in this case, the SP should advise
   the customer about the limitations.  How this communication is done
   is out of scope for this document.

5.10.3.  Support for BUM

   The "broadcast-unknown-unicast-multicast" container defines the type
   of site in the customer multicast service topology: source, receiver,
   or both.  These parameters will help the management system optimize
   the multicast service.

   Multiple multicast group-to-port mappings can be created using the
   "multicast-gp-address-mapping" list.  The
   "multicast-gp-address-mapping" list defines the multicast group
   address and port LAG number.  Those parameters will help the SP
   select the appropriate association between an interface and a
   multicast group to fulfill the customer service requirement.

   To ensure that a given frame is transparently transported, a whole
   Layer 2 multicast frame (whether for data or control) should not be
   altered from a CE to other CEs, except for the VLAN ID field.  VLAN
   IDs assigned by the SP can also be altered.

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   For point-to-point services, the provider only needs to deliver a
   single copy of each service frame to the remote PE, regardless of
   whether the destination MAC address of the incoming frame is unicast,
   multicast, or broadcast.  Therefore, all service frames should be
   delivered unconditionally.

   BUM frame forwarding in multipoint-to-multipoint services, on the
   other hand, involves both local flooding to other ACs on the same PE
   and remote replication to all other PEs, thus consuming additional
   resources and core bandwidth.  Special BUM frame disposition rules
   can be implemented at external-facing interfaces (UNIs or External
   NNIs (E-NNIs)) to rate-limit the BUM frames, in terms of the number
   of packets per second or bits per second.

   The threshold can apply to all BUM traffic, or one threshold can be
   applied for each category of traffic.

5.11.  Site Management

   The "management" sub-container is intended for site management
   options, depending on device ownership and security access control.
   Three common management models are as follows:

   Provider-managed CE:  The provider has sole ownership of the CE
      device.  Only the provider has access to the CE.  The
      responsibility boundary between the SP and the customer is between
      the CE and the customer network.  This is the most common
      use case.

   Customer-managed CE:  The customer has sole ownership of the CE
      device.  Only the customer has access to the CE.  In this model,
      the responsibility boundary between the SP and the customer is
      between the PE and the CE.

   Co-managed CE:  The provider has ownership of the CE device and is
      responsible for managing the CE.  However, the provider grants the
      customer access to the CE for some configuration/monitoring
      purposes.  In this co-managed mode, the responsibility boundary is
      the same as for the provider-managed model.

   The selected management mode is specified under the "type" leaf.  The
   "address" leaf stores CE device management addressing information.
   The "management-transport" leaf is used to identify the transport
   protocol for management traffic: IPv4 or IPv6.  Additional security
   options may be derived based on the particular management model
   selected.

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5.12.  MAC Loop Protection

   MAC address flapping between different physical ports typically
   indicates a bridge loop condition in the customer network.
   Misleading entries in the MAC cache table can cause service frames to
   circulate around the network indefinitely and saturate the links
   throughout the provider's network, affecting other services in the
   same network.  In the case of EVPNs, it also introduces massive BGP
   updates and control-plane instability.

   The SP may opt to implement a switching loop-prevention mechanism at
   the external-facing interfaces for multipoint-to-multipoint services
   by imposing a MAC address move threshold.

   The MAC move rate and prevention-type options are listed in the
   "mac-loop-prevention" container.

5.13.  MAC Address Limit

   The optional "mac-addr-limit" container contains the customer MAC
   address limit and information that describes the action taken when
   the limit is exceeded and the aging time for a MAC address.

   When multiple services are provided on the same network element, the
   MAC address table (and the Routing Information Base space for
   MAC routes in the case of EVPNs) is a shared common resource.  SPs
   may impose a maximum number of MAC addresses learned from the
   customer for a single service instance by using the "mac-addr-limit"
   leaf and may use the "action" leaf to specify the action taken when
   the upper limit is exceeded: drop the packet, flood the packet, or
   simply send a warning log message.

   For point-to-point services, if MAC learning is disabled, then the
   MAC address limit is not necessary.

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5.14.  Enhanced VPN Features

5.14.1.  Carriers' Carriers

   In the case of Carriers' Carriers (CsC) [RFC8299], a customer may
   want to build an MPLS service using an L2VPN to carry its traffic.

                 LAN customer1
                    |
                    |
                   CE1
                    |
                    | -------------
                 (vrf_cust1)
                  CE1_ISP1
                    |                 ISP1 POP
                    | MPLS link
                    | -------------
                    |
                 (vrf ISP1)
                   PE1

                  (...)               Provider backbone

                   PE2
                  (vrf ISP1)
                    |
                    | ------------
                    |
                    | MPLS link
                    |                 ISP1 POP
                   CE2_ISP1
                   (vrf_cust1)
                    | ------------
                    |
                   CE2
                    |
                 LAN customer1

          Figure 21: MPLS Service Using an L2VPN to Carry Traffic

   In Figure 21, ISP1 resells an L2VPN service but has no core network
   infrastructure between its POPs.  ISP1 uses an L2VPN as the core
   network infrastructure (belonging to another provider) between
   its POPs.

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   In order to support CsC, the VPN service must indicate MPLS support
   by setting the "carrierscarrier" leaf to "true" in the vpn-service
   list.  The link between CE1_ISP1/PE1 and CE2_ISP1/PE2 must also run
   an MPLS signaling protocol.  This configuration is done at the site
   level.

   In this model, LDP or BGP can be used as the MPLS signaling protocol.
   In the case of LDP, an IGP routing protocol MUST also be activated.
   In the case of BGP signaling, BGP MUST also be configured as the
   routing protocol.

   If CsC is enabled, the requested "svc-mtu" leaf will refer to the
   MPLS MTU and not to the link MTU.

5.15.  External ID References

   The service model sometimes refers to external information through
   identifiers.  As an example, to order cloud access to a particular
   Cloud Service Provider (CSP), the model uses an identifier to refer
   to the targeted CSP.  If a customer is directly using this service
   model as an API (through RESTCONF or NETCONF, for example) to order a
   particular service, the SP should provide a list of authorized
   identifiers.  In the case of cloud access, the SP will provide the
   associated identifiers for each available CSP.  The same applies to
   other identifiers, such as qos-profile.

   As a usage example, the remote-carrier-name setting is used in the
   NNI case because it should be known by the current L2VPN SP to which
   it is connecting, while the cloud-identifier setting should be known
   by both the current L2VPN SP and the customer because it is applied
   to the public cloud or Internet access.

   How an SP provides the meanings of those identifiers to the customer
   is out of scope for this document.

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5.16.  Defining NNIs and Inter-AS Support

   An Autonomous System (AS) is a single network or group of networks
   that are controlled by a common system administration group and that
   use a single, clearly defined routing protocol.  In some cases, VPNs
   need to span different ASes in different geographical areas or span
   different SPs.  The connection between ASes is established by the SPs
   and is seamless to the customer.  Examples include:

   o  A partnership between SPs (e.g., carrier, cloud) to extend their
      VPN services seamlessly.

   o  An internal administrative boundary within a single SP (e.g.,
      backhaul versus core versus data center).

   NNIs have to be defined to extend the VPNs across multiple ASes.
   [RFC4761] defines multiple flavors of VPN NNI implementations (e.g.,
   VPLSs).  Each implementation has pros and cons; this topic is outside
   the scope of this document.  For example, in an inter-AS option A
   (two ASes), AS Border Router (ASBR) peers are connected by multiple
   interfaces with at least one of those interfaces spanning the two
   ASes while being present in the same VPN.  In order for these ASBRs
   to signal label blocks, they associate each interface with a MAC-VRF
   (VSI) (Section 2) and a BGP session.  As a result, traffic between
   devices in the back-to-back VPLS is Ethernet.  In this scenario, the
   VPNs are isolated from each other, and because the traffic is
   Ethernet, QoS mechanisms that operate on Ethernet traffic can be
   applied to achieve customer SLAs.

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      --------                 --------------              -----------
     /        \               /              \            /           \
    | Cloud    |             |                |          |             |
    | Provider |-----NNI-----|                |----NNI---| Data Center |
    |  #1      |             |                |          |             |
     \        /              |                |           \           /
      --------               |                |            -----------
                             |                |
      --------               |   My network   |           -----------
     /        \              |                |          /           \
    | Cloud    |             |                |         |             |
    | Provider |-----NNI-----|                |---NNI---|  L2VPN      |
    |  #2      |             |                |         |  Partner    |
     \        /              |                |         |             |
      --------               |                |         |             |
                              \              /          |             |
                               --------------            \           /
                                     |                    -----------
                                     |
                                    NNI
                                     |
                                     |
                             -------------------
                            /                   \
                           |                     |
                           |                     |
                           |                     |
                           |     L2VPN Partner   |
                           |                     |
                            \                   /
                             -------------------

                  Figure 22: SP Network with Several NNIs

   Figure 22 illustrates an SP network called "My network" that has
   several NNIs.  This network uses NNIs to:

   o  increase its footprint by relying on L2VPN partners.

   o  connect its own data-center services to the customer L2VPN.

   o  enable the customer to access its private resources located in a
      private cloud owned by some CSPs.

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5.16.1.  Defining an NNI with the Option A Flavor

              AS A                                         AS B
       -------------------                         -------------------
      /                   \                       /                   \
     |                     |                     |                     |
     |                 ++++++++ Inter-AS link +++++++++                |
     |                 +      +_______________+       +                |
     |                 +(MAC-VRF1)--(VPN1)--(MAC-VRF1)+                |
     |                 +      +               +       +                |
     |                 + ASBR +               + ASBR  +                |
     |                 +      +               +       +                |
     |                 +(MAC-VRF2)--(VPN2)--(MAC-VRF2)+                |
     |                 +      +_______________+       +                |
     |                 ++++++++               +++++++++                |
     |                     |                     |                     |
     |                     |                     |                     |
     |                     |                     |                     |
     |                 ++++++++ Inter-AS link +++++++++                |
     |                 +      +_______________+       +                |
     |                 +(MAC-VRF1)--(VPN1)--(MAC-VRF1)+                |
     |                 +      +               +       +                |
     |                 + ASBR +               + ASBR  +                |
     |                 +      +               +       +                |
     |                 +(MAC-VRF2)--(VPN2)--(MAC-VRF2)+                |
     |                 +      +_______________+       +                |
     |                 ++++++++               +++++++++                |
     |                     |                     |                     |
     |                     |                     |                     |
      \                   /                       \                   /
       -------------------                         -------------------

        Figure 23: NNI Defined with the Option A Flavor: Example 1

   In option A, the two ASes are connected to each other with physical
   links on ASBRs.  For resiliency purposes, there may be multiple
   physical connections between the ASes.  A VPN connection -- physical
   or logical (on top of physical) -- is created for each VPN that needs
   to cross the AS boundary, thus providing a back-to-back VPLS model.

   From a service model's perspective, this VPN connection can be seen
   as a site.  Let's say that AS B wants to extend some VPN connections
   for VPN C on AS A.  The administrator of AS B can use this service
   model to order a site on AS A.  All connection scenarios could be
   realized using the features of the current model.  As an example,
   Figure 23 shows two physical connections that have logical
   connections per VPN overlaid on them.  This could be seen as a
   multi-VPN scenario.  Also, the administrator of AS B will be able to

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   choose the appropriate routing protocol (e.g., External BGP (EBGP))
   to dynamically exchange routes between ASes.

   This document assumes that the option A NNI flavor SHOULD reuse the
   existing VPN site modeling.

   Figure 24 illustrates an example where a customer wants its CSP A to
   attach its virtual network N to an existing L2VPN (VPN1) that it has
   from L2VPN SP B.

               CSP A                           L2VPN SP B
        -----------------                     -----------
       /                 \                   /           \
      |       |           |                 |             |
      |  VM --|       ++++++++     NNI    ++++++++++      |--- VPN1
      |       |       +      +____________+        +      |   Site 1
      |       |-------+(MAC-VRF1)-(VPN1)-(MAC-VRF1)+      |
      |       |       +      +            +        +      |
      |       |       + ASBR +            + ASBR   +      |
      |       |       +      +____________+        +      |
      |       |       ++++++++            ++++++++++      |
      |  VM --|           |                 |             |--- VPN1
      |       |Virtual    |                 |             |   Site 2
      |       |Network    |                 |             |
      |  VM --|           |                 |             |--- VPN1
      |       |           |                 |             |   Site 3
       \                 /                   \           /
        -----------------                     -----------
                                                   |
                                                   |
                                                  VPN1
                                                 Site 4

      VM = Virtual Machine

        Figure 24: NNI Defined with the Option A Flavor: Example 2

   To create the VPN connectivity, the CSP or the customer may use the
   L2SM that SP B exposes.  We could consider that, as the NNI is
   shared, the physical connection (bearer) between CSP A and SP B
   already exists.  CSP A may request through a service model the
   creation of a new site with a single site-network-access
   (single-homing is used in Figure 24).  As a placement constraint, CSP
   A may use the existing bearer reference it has from SP A to force the
   placement of the VPN NNI on the existing link.  The XML below
   illustrates a possible configuration request to SP B:

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   <?xml version="1.0"?>
   <l2vpn-svc xmlns="urn:ietf:params:xml:ns:yang:ietf-l2vpn-svc">
    <vpn-profiles>
     <valid-provider-identifiers>
      <qos-profile-identifier>
       <id>GOLD</id>
      </qos-profile-identifier>
      <qos-profile-identifier>
       <id>PLATINUM</id>
      </qos-profile-identifier>
     </valid-provider-identifiers>
    </vpn-profiles>
    <vpn-services>
     <vpn-service>
      <vpn-id>VPN1</vpn-id>
      <ce-vlan-preservation>true</ce-vlan-preservation>
      <ce-vlan-cos-preservation>true</ce-vlan-cos-preservation>
     </vpn-service>
    </vpn-services>
    <sites>
         <site>
             <site-id>CSP_A_attachment</site-id>
              <locations>
               <location>
                 <location-id>NY1</location-id>
                 <city>NY</city>
                 <country-code>US</country-code>
              </location>
              </locations>
             <site-vpn-flavor>site-vpn-flavor-nni</site-vpn-flavor>
               <site-network-accesses>
                 <site-network-access>
                  <network-access-id>CSP_A_VN1</network-access-id>
                          <connection>
                          <encapsulation-type>vlan</encapsulation-type>
                          <eth-inf-type>tagged</eth-inf-type>
                           <tagged-interface>
                            <tagged-inf-type>dot1q</tagged-inf-type>
                            <dot1q-vlan-tagged>
                             <cvlan-id>17</cvlan-id>
                           </dot1q-vlan-tagged>
                           </tagged-interface>
                          </connection>
                            <service>
                              <svc-bandwidth>
                                <bandwidth>
                                 <direction>input-bw</direction>
                                  <type>bw-per-cos</type>

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                                   <cir>450000000</cir>
                                   <cbs>20000000</cbs>
                                   <eir>1000000000</eir>
                                   <ebs>200000000</ebs>
                                </bandwidth>
                              </svc-bandwidth>
                              <carrierscarrier>
                                <signaling-type>bgp</signaling-type>
                             </carrierscarrier>
                            </service>
                           <vpn-attachment>
                              <vpn-id>12456487</vpn-id>
                              <site-role>spoke-role</site-role>
                            </vpn-attachment>
                </site-network-access>
             </site-network-accesses>
             <management>
              <type>customer-managed</type>
             </management>
         </site>
    </sites>
   </l2vpn-svc>

   The case described above is different from a scenario using the
   cloud-accesses container, as the cloud-access provides a public cloud
   access while this example enables access to private resources located
   in a CSP network.

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5.16.2.  Defining an NNI with the Option B Flavor

            AS A                                          AS B
      -------------------                         -------------------
     /                   \                       /                   \
    |                     |                     |                     |
    |                 ++++++++ Inter-AS link ++++++++                 |
    |                 +      +_______________+      +                 |
    |                 +      +               +      +                 |
    |                 + ASBR +<---MP-BGP---->+ ASBR +                 |
    |                 +      +               +      +                 |
    |                 +      +_______________+      +                 |
    |                 ++++++++               ++++++++                 |
    |                     |                     |                     |
    |                     |                     |                     |
    |                     |                     |                     |
    |                 ++++++++ Inter-AS link ++++++++                 |
    |                 +      +_______________+      +                 |
    |                 +      +               +      +                 |
    |                 + ASBR +<---MP-BGP---->+ ASBR +                 |
    |                 +      +               +      +                 |
    |                 +      +_______________+      +                 |
    |                 ++++++++               ++++++++                 |
    |                     |                     |                     |
    |                     |                     |                     |
     \                   /                       \                   /
      -------------------                         -------------------

        Figure 25: NNI Defined with the Option B Flavor: Example 1

   In option B, the two ASes are connected to each other with physical
   links on ASBRs.  For resiliency purposes, there may be multiple
   physical connections between the ASes.  The VPN "connection" between
   ASes is done by exchanging VPN routes through MP-BGP [RFC4761].

   There are multiple flavors of implementations of such an NNI.  For
   example:

   1.  The NNI is internal to the provider and is situated between a
       backbone and a data center.  There is enough trust between the
       domains to not filter the VPN routes.  So, all the VPN routes are
       exchanged.  RT filtering may be implemented to save some
       unnecessary route states.

   2.  The NNI is used between providers that agreed to exchange VPN
       routes for specific RTs only.  Each provider is authorized to use
       the RT values from the other provider.

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   3.  The NNI is used between providers that agreed to exchange VPN
       routes for specific RTs only.  Each provider has its own RT
       scheme.  So, a customer spanning the two networks will have
       different RTs in each network for a particular VPN.

   Case 1 does not require any service modeling, as the protocol enables
   the dynamic exchange of necessary VPN routes.

   Case 2 requires that an RT-filtering policy on ASBRs be maintained.
   From a service-modeling point of view, it is necessary to agree on
   the list of RTs to authorize.

   In Case 3, both ASes need to agree on the VPN RT to exchange, as well
   as how to map a VPN RT from AS A to the corresponding RT in AS B (and
   vice versa).

   Those modelings are currently out of scope for this document.

           CSP A                               L3VPN SP B
      -----------------                    ------------------
     /                 \                  /                  \
    |       |           |                |                    |
    |  VM --|       ++++++++   NNI    ++++++++                |--- VPN1
    |       |       +      +__________+      +                |   Site 1
    |       |-------+      +          +      +                |
    |       |       + ASBR +<-MP-BGP->+ ASBR +                |
    |       |       +      +__________+      +                |
    |       |       ++++++++          ++++++++                |
    |  VM --|           |                |                    |--- VPN1
    |       |Virtual    |                |                    |   Site 2
    |       |Network    |                |                    |
    |  VM --|           |                |                    |--- VPN1
    |       |           |                |                    |   Site 3
     \                 /                 |                    |
      -----------------                  |                    |
                                          \                  /
                                           ------------------
                                                    |
                                                    |
                                                   VPN1
                                                  Site 4

      VM = Virtual Machine

        Figure 26: NNI Defined with the Option B Flavor: Example 2

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   Figure 26 shows an NNI connection between CSP A and SP network B.
   The SPs do not trust each other and use different RT allocation
   policies.  So, in terms of implementation, the customer VPN has a
   different RT in each network (RT A in CSP A and RT B in SP
   network B).  In order to connect the customer's virtual network in
   CSP A to the customer's L2VPN (VPN1) in SP network B, CSP A should
   request that SP network B open the customer VPN on the NNI (accept
   the appropriate RT).  Who does the RT translation depends on the
   agreement between the two SPs: SP B may permit CSP A to request VPN
   (RT) translation.

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5.16.3.  Defining an NNI with the Option C Flavor

             AS A                                           AS B
      -------------------                          -------------------
     /                   \                        /                   \
    |                     |                      |                     |
    |                     |                      |                     |
    |                     |                      |                     |
    |                 ++++++++ Multihop EBGP  ++++++++                 |
    |                 +      +                +      +                 |
    |                 +      +                +      +                 |
    |                 + RGW  +<----MP-BGP---->+ RGW  +                 |
    |                 +      +                +      +                 |
    |                 +      +                +      +                 |
    |                 ++++++++                ++++++++                 |
    |                     |                      |                     |
    |                     |                      |                     |
    |                     |                      |                     |
    |                     |                      |                     |
    |                     |                      |                     |
    |                 ++++++++ Inter-AS link ++++++++                  |
    |                 +      +_______________+      +                  |
    |                 +      +               +      +                  |
    |                 + ASBR +               + ASBR +                  |
    |                 +      +               +      +                  |
    |                 +      +_______________+      +                  |
    |                 ++++++++               ++++++++                  |
    |                     |                      |                     |
    |                     |                      |                     |
    |                     |                      |                     |
    |                 ++++++++ Inter-AS link ++++++++                  |
    |                 +      +_______________+      +                  |
    |                 +      +               +      +                  |
    |                 + ASBR +               + ASBR +                  |
    |                 +      +               +      +                  |
    |                 +      +_______________+      +                  |
    |                 ++++++++               ++++++++                  |
    |                     |                      |                     |
    |                     |                      |                     |
     \                   /                        \                   /
      -------------------                          -------------------

              Figure 27: NNI Defined with the Option C Flavor

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   From a VPN service's perspective, the option C NNI is very similar to
   option B, as an MP-BGP session is used to exchange VPN routes between
   the ASes.  The difference is that the forwarding plane and the
   control plane are on different nodes, so the MP-BGP session is
   multihop between routing gateway (RGW) nodes.  From a VPN service's
   point of view, modeling options B and C will be configured
   identically.

5.17.  Applicability of L2SM in Inter-provider and Inter-domain
       Orchestration

   In the case where the ASes belong to different providers, one might
   imagine that providers would like to have fewer signaling sessions
   crossing the AS boundary and that the entities that terminate the
   sessions could be restricted to a smaller set of devices.  Two
   approaches can be taken:

   a.  Construct inter-provider control connections to run only between
       the two border routers.

   b.  Allow end-to-end, multi-segment connectivity to be constructed
       out of several connectivity segments, without maintaining an
       end-to-end control connection.

   Inter-provider control connections as described in approach (a) can
   be realized using the techniques provided in Section 5.16 (e.g.,
   defining NNIs).  Multi-segment connectivity as described in
   approach (b) can produce an inter-AS solution that more closely
   resembles scheme (b) in Section 10 of [RFC4364].  It may be realized
   using "stitching" of per-site connectivity and service segments at
   different domains, e.g., end-to-end connectivity between Site 1 and
   Site 3 spans multiple domains (e.g., metropolitan area networks) and
   can be constructed by stitching network access connectivity within
   Site 1 with SEG1, SEG3, and SEG4, and network access connectivity
   within Site 3 (as shown in Figure 28).  The assumption is that the
   service orchestration component in Figure 3 should have visibility
   into the complete abstract topology and resource availability.  This
   may rely on network planning.

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             ----------   ----------   ----------
            |          | |          | |          |
          +--+        +---+        +---+        +--+
    Site 1|PE|==SEG1==|   |==SEG3==|   |==SEG4==|PE|Site 3
          +--+        +---+        |   |        +--+
            |          | |         |   |         |  ----------
            |          | |         |   |         | |          |
          +--+        +---+        |   |        +---+        +--+
    Site 2|PE|==SEG2==|   |==SEG5==|   |==SEG6==|   |==SEG7==|PE|Site 4
          +--+        +---+        +---+        +---+        +--+
            |          | |          | |          | |          |
             ----------   ----------   ----------   ----------

     Figure 28: Example: Inter-provider and Inter-domain Orchestration

   Note that SEG1, SEG2, SEG3, SEG4, SEG5, and SEG6 can also be regarded
   as network access connectivity within a site and can be created as a
   normal site using the L2SM.

   In Figure 28, we use BGP redistribution of L2VPN Network Layer
   Reachability Information (NLRI) instances from AS to neighboring AS.
   First, the PE routers use BGP to redistribute L2VPN NLRIs to either
   an ASBR or a route reflector of which an ASBR is a client.  The ASBR
   then uses BGP to redistribute those L2VPN NLRIs to an ASBR in another
   AS, which in turn distributes them to the PE routers in that AS, or
   perhaps to another ASBR that in turn distributes them, and so on.

   In this case, a PE can learn the address of an ASBR through which it
   could reach another PE to which it wishes to establish connectivity.
   That is, a local PE will receive a BGP advertisement containing an
   L2VPN NLRI corresponding to an L2VPN instance in which the local PE
   has some attached members.  The BGP next hop for that L2VPN NLRI will
   be an ASBR of the local AS.  Then, rather than building a control
   connection all the way to the remote PE, it builds one only to the
   ASBR.  A connectivity segment can now be established from the PE to
   the ASBR.  The ASBR in turn can establish connectivity to the ASBR of
   the next AS and then stitch that connectivity to the connectivity
   from the PE as described in [RFC6073].  Repeating the process at each
   ASBR leads to a sequence of connectivity segments that, when stitched
   together, connect the two PEs.

   Note that in the approach just described, the local PE may never
   learn the IP address of the remote PE.  It learns the L2VPN NLRI
   advertised by the remote PE, which need not contain the remote PE
   address, and it learns the IP address of the ASBR that is the BGP
   next hop for that NLRI.

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   When this approach is used for VPLS or for full-mesh VPWS, it leads
   to a full mesh of connectivity among the PEs, but it does not require
   a full mesh of control connections (LDP or L2TPv3 sessions).
   Instead, the control connections within a single AS run among all the
   PEs of that AS and the ASBRs of the AS.  A single control connection
   between the ASBRs of adjacent ASes can be used to support as many
   AS-to-AS connectivity segments as may be needed.

6.  Interaction with Other YANG Modules

   As explained in Section 4, this service model is not intended to
   configure network elements; rather, it is instantiated in a
   management system.

   The management system might follow modular design and comprise two
   different components:

   a.  The component instantiating the service model (let's call it the
       service component).

   b.  The component responsible for network element configuration
       (let's call it the configuration component).

   In some cases, when a split is needed between the behavior and
   functions that a customer requests and the technology that the
   network operator has available to deliver the service [RFC8309], a
   new component can be separated out of the service component (let's
   call it the control component).  This component is responsible for
   network-centric operation and is aware of many features such as
   topology, technology, and operator policy.  As an optional component,
   it can use the service model as input and is not required at all if
   the control component delegates its control operations to the
   configuration component.

   In Section 7, we provide an example of translation of service
   provisioning requests to router configuration lines as an
   illustration.  In the YANG-based ecosystem, it is expected that
   NETCONF and YANG will be used between the configuration component and
   network elements to configure the requested service on those
   elements.

   In this framework, it is expected that YANG data models will be used
   to configure service components on network elements.  There will be a
   strong relationship between the abstracted view provided by this
   service model and the detailed configuration view that will be
   provided by specific configuration models for network elements such

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   as those defined in [MPLS-L2VPN-YANG] and [EVPN-YANG].  Service
   components that would need configuration of network elements in
   support of the service model defined in this document include:

   o  Network instance definitions that include defined VPN policies.

   o  Physical interfaces.

   o  Ethernet-layer parameters (e.g., VLAN IDs).

   o  QoS: classification, profiles, etc.

   o  Support for Ethernet Service OAM.

7.  Service Model Usage Example

   As explained in Section 4, this service model is intended to be
   instantiated at a management layer and is not intended to be used
   directly on network elements.  The management system serves as a
   central point of configuration of the overall service.

   This section provides an example of how a management system can use
   this model to configure an L2VPN service on network elements.

   This example provides a VPN service for three sites using
   point-to-point VPWS and a Hub-and-Spoke VPN service topology as shown
   in Figure 29.  Load balancing is not considered in this case.

     Site 1
     ............
     :          :             P2P VPWS
     :Spoke Site:-----PE1--------------------------+
     :          :                                  |        Site 3
     :..........:                                  |      ............
                                                   |      :          :
                                                  PE3-----: Hub Site :
     Site 2                                        |      :          :
     ............                                  |      :..........:
     :          :             P2P VPWS             |
     :Spoke Site:-----PE2--------------------------+
     :          :
     :..........:

              Figure 29: Reference Network for Simple Example

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   The following XML describes the overall simplified service
   configuration of this VPN.

       <?xml version="1.0"?>
       <l2vpn-svc xmlns="urn:ietf:params:xml:ns:yang:ietf-l2vpn-svc">
         <vpn-services>
             <vpn-service>
              <vpn-id>12456487</vpn-id>
               <vpn-svc-type>vpws</vpn-svc-type>
               <svc-topo>hub-spoke</svc-topo>
               <ce-vlan-preservation>true</ce-vlan-preservation>
               <ce-vlan-cos-preservation>true</ce-vlan-cos-preservation>
              </vpn-service>
             <vpn-service>
               <vpn-id>12456488</vpn-id>
               <vpn-svc-type>vpws</vpn-svc-type>
               <svc-topo>hub-spoke</svc-topo>
               <ce-vlan-preservation>true</ce-vlan-preservation>
               <ce-vlan-cos-preservation>true</ce-vlan-cos-preservation>
              </vpn-service>
         </vpn-services>
       </l2vpn-svc>

   When receiving the request for provisioning the VPN service, the
   management system will internally (or through communication with
   another OSS component) allocate VPN RTs.  In this specific case, two
   RTs will be allocated (100:1 for Hubs and 100:2 for Spokes).  The
   output below describes the configuration of Spoke Site 1.

  <?xml version="1.0"?>
  <l2vpn-svc xmlns="urn:ietf:params:xml:ns:yang:ietf-l2vpn-svc">
   <vpn-services>
    <vpn-service>
     <vpn-id>12456487</vpn-id>
     <svc-topo>hub-spoke</svc-topo>
     <ce-vlan-preservation>true</ce-vlan-preservation>
     <ce-vlan-cos-preservation>true</ce-vlan-cos-preservation>
    </vpn-service>
   </vpn-services>
   <sites>
     <site>
        <site-id>Spoke_Site1</site-id>
           <locations>
             <location>
              <location-id>NY1</location-id>
              <city>NY</city>
              <country-code>US</country-code>
             </location>

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            </locations>
            <site-network-accesses>
               <site-network-access>
                  <network-access-id>Spoke_UNI-Site1</network-access-id>
                    <access-diversity>
                      <groups>
                        <group>
                          <group-id>20</group-id>
                        </group>
                      </groups>
                    </access-diversity>
                      <connection>
                       <encapsulation-type>vlan</encapsulation-type>
                        <tagged-interface>
                        <dot1q-vlan-tagged>
                          <cvlan-id>17</cvlan-id>
                        </dot1q-vlan-tagged>
                        </tagged-interface>
                        <l2cp-control>
                          <stp-rstp-mstp>tunnel</stp-rstp-mstp>
                          <lldp>true</lldp>
                        </l2cp-control>
                      </connection>
                      <service>
                        <svc-bandwidth>
                          <bandwidth>
                           <direction>input-bw</direction>
                            <type>bw-per-cos</type>
                             <cir>450000000</cir>
                             <cbs>20000000</cbs>
                             <eir>1000000000</eir>
                             <ebs>200000000</ebs>
                          </bandwidth>
                        </svc-bandwidth>
                        <carrierscarrier>
                         <signaling-type>bgp</signaling-type>
                        </carrierscarrier>
                     </service>
                      <vpn-attachment>
                        <vpn-id>12456487</vpn-id>
                        <site-role>spoke-role</site-role>
                      </vpn-attachment>
                    </site-network-access>
                  </site-network-accesses>
                  <management>
                    <type>provider-managed</type>
                  </management>
                </site>

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          </sites>
      </l2vpn-svc>

   When receiving the request for provisioning Spoke Site 1, the
   management system MUST allocate network resources for this site.  It
   MUST first determine the target network elements to provision the
   access and, in particular, the PE router (or possibly an aggregation
   switch).  As described in Sections 5.3.1 and 5.6, the management
   system SHOULD use the location information and MUST use the
   access-diversity constraint to find the appropriate PE.  In this
   case, we consider that Spoke Site 1 requires PE diversity with Hubs
   and that the management system will allocate PEs based on least
   distance.  Based on the location information, the management system
   finds the available PEs in the area closest to the customer and picks
   one that fits the access-diversity constraint.

   When the PE is chosen, the management system needs to allocate
   interface resources on the node.  One interface is selected from the
   PE's available pool of resources.  The management system can start
   provisioning the PE node using any means it wishes (e.g., NETCONF,
   CLI).  The management system will check to see if a VSI that fits its
   needs is already present.  If not, it will provision the VSI: the RD
   will come from the internal allocation policy model, and the RTs will
   come from the vpn-policy configuration of the site (i.e., the
   management system will allocate some RTs for the VPN).  As the site
   is a Spoke site (site-role), the management system knows which RTs
   must be imported and exported.  As the site is provider managed, some
   management RTs may also be added (100:5000).  Standard provider VPN
   policies MAY also be added in the configuration.

   Example of a generated PE configuration:

l2vpn vsi context one
  vpn id 12456487
     autodiscovery bgp signaling bgp
     ve id 1001     <---- identify the PE routers within the VPLS domain
     ve range 50    <---- VPLS Edge (VE) size
     route-distinguisher 100:3123234324
     route-target import 100:1
     route-target import 100:5000    <---- Standard SP configuration
     route-target export 100:2               for provider-managed CE
   !

   When the VSI has been provisioned, the management system can start
   configuring the access on the PE using the allocated interface
   information.  The tag or VLAN (e.g., service instance tag) is chosen
   by the management system.  One tag will be picked from an allocated
   subnet for the PE, and another will be used for the CE configuration.

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   LACP protocols will also be configured between the PE and the CE; in
   the case of the provider-managed model, the choice is left to the SP.
   This choice is independent of the LACP protocol chosen by the
   customer.

   Example of a generated PE configuration:

   !
   bridge-domain 1
    member Ethernet0/0 service-instance 100
    member vsi one
   !
   l2 router-id 198.51.100.1
   !
   l2 router-id 2001:db8::10:1/64
   !

   interface Ethernet0/0
    no ip address
    service instance 100 ethernet
   encapsulation dot1q 100
    !

   !
   router bgp 1
    bgp log-neighbor-changes
    neighbor 198.51.100.4 remote-as 1
    neighbor 198.51.100.4 update-source Loopback0
    !
    address-family l2vpn vpls
     neighbor 198.51.100.4 activate
     neighbor 198.51.100.4 send-community extended
     neighbor 198.51.100.4 suppress-signaling-protocol ldp
     neighbor 2001:db8::0a10:4 activate
     neighbor 2001:db8::0a10:4 send-community extended
    exit-address-family

   !
   interface vlan 100     <---- Associating the AC with
     no ip address                the MAC-VRF at the PE
     xconnect vsi PE1-VPLS-A
   !
   vlan 100
     state active

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   As the CE router is not reachable at this stage, the management
   system can produce a complete CE configuration that can be manually
   uploaded to the node (e.g., before sending the CE to the customer
   premises at the appropriate postal address, as described in
   Section 5.3.1).  The CE configuration will be built in the same way
   as the PE configuration is built.  Based on (1) the CE type
   (vendor/model) allocated to the customer and (2) bearer information,
   the management system knows which interface must be configured on the
   CE.  PE-CE link configuration is expected to be handled automatically
   using the SP's OSS, as both resources are managed internally.
   CE-to-LAN interface parameters, such as dot1Q tags, are derived from
   the Ethernet connection, taking into account how the management
   system distributes dot1Q tags between the PE and the CE within the
   subnet.  This will allow a plug'n'play configuration to be produced
   for the CE.

   Example of a generated CE configuration:

   interface Ethernet0/1
     switchport trunk allowed vlan none
     switchport mode trunk
     service instance 100 ethernet
     encapsulation default
     l2protocol forward cdp
     xconnect 203.0.113.1 100 encapsulation mpls
   !

8.  YANG Module

   This YANG module imports typedefs from [RFC6991] and [RFC8341].

<CODE BEGINS> file "ietf-l2vpn-svc@2018-10-09.yang"
module ietf-l2vpn-svc {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-l2vpn-svc";
  prefix l2vpn-svc;

  import ietf-inet-types {
    prefix inet;
  }
  import ietf-yang-types {
    prefix yang;
  }
  import ietf-netconf-acm {
    prefix nacm;
  }

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  organization
    "IETF L2SM Working Group.";
  contact
    "WG Web:   <https://datatracker.ietf.org/wg/l2sm/>
     WG List:  <mailto:l2sm@ietf.org>
     Editor:   Giuseppe Fioccola
               <mailto:giuseppe.fioccola@tim.it>";
  description
    "This YANG module defines a generic service configuration model
     for Layer 2 VPN services common across all vendor
     implementations.

     Copyright (c) 2018 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 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 8466;
     see the RFC itself for full legal notices.";

  revision 2018-10-09 {
    description
      "Initial revision.";
    reference
      "RFC 8466: A YANG Data Model for Layer 2 Virtual Private
       Network (L2VPN) Service Delivery";
  }

  feature carrierscarrier {
    description
      "Enables the support of carriers' carriers (CsC).";
  }

  feature ethernet-oam {
    description
      "Enables the support of Ethernet Service OAM.";
  }

  feature extranet-vpn {
    description
      "Enables the support of extranet VPNs.";
  }

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  feature l2cp-control {
    description
      "Enables the support of L2CP control.";
  }

  feature input-bw {
    description
      "Enables the support of input bandwidth in a VPN.";
  }

  feature output-bw {
    description
      "Enables the support of output bandwidth in a VPN.";
  }

  feature uni-list {
    description
      "Enables the support of a list of UNIs in a VPN.";
  }

  feature cloud-access {
    description
      "Allows the VPN to connect to a Cloud Service Provider (CSP)
       or an ISP.";
  }

  feature oam-3ah {
    description
      "Enables the support of OAM 802.3ah.";
  }

  feature micro-bfd {
    description
      "Enables the support of micro-BFD.";
  }

  feature bfd {
    description
      "Enables the support of BFD.";
  }

  feature signaling-options {
    description
      "Enables the support of signaling options.";
  }

  feature site-diversity {
    description

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      "Enables the support of site diversity constraints in a VPN.";
  }

  feature encryption {
    description
      "Enables the support of encryption.";
  }

  feature always-on {
    description
      "Enables support for the 'always-on' access constraint.";
  }

  feature requested-type {
    description
      "Enables support for the 'requested-type' access constraint.";
  }

  feature bearer-reference {
    description
      "Enables support for the 'bearer-reference' access
       constraint.";
  }

  feature qos {
    description
      "Enables support for QoS.";
  }

  feature qos-custom {
    description
      "Enables the support of a custom QoS profile.";
  }

  feature lag-interface {
    description
      "Enables LAG interfaces.";
  }

  feature vlan {
    description
      "Enables the support of VLANs.";
  }

  feature dot1q {
    description
      "Enables the support of dot1Q.";
  }

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  feature qinq {
    description
      "Enables the support of QinQ.";
  }

  feature qinany {
    description
      "Enables the support of QinAny.";
  }

  feature vxlan {
    description
      "Enables the support of VXLANs.";
  }

  feature lan-tag {
    description
      "Enables LAN tag support in a VPN.";
  }

  feature target-sites {
    description
      "Enables the support of the 'target-sites'
       match-flow parameter.";
  }

  feature bum {
    description
      "Enables BUM capabilities in a VPN.";
  }

  feature mac-loop-prevention {
    description
      "Enables the MAC loop-prevention capability in a VPN.";
  }

  feature lacp {
    description
      "Enables the Link Aggregation Control Protocol (LACP)
       capability in a VPN.";
  }

  feature mac-addr-limit {
    description
      "Enables the MAC address limit capability in a VPN.";
  }

  feature acl {

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    description
      "Enables the ACL capability in a VPN.";
  }

  feature cfm {
    description
      "Enables the 802.1ag CFM capability in a VPN.";
  }

  feature y-1731 {
    description
      "Enables the Y.1731 capability in a VPN.";
  }

  typedef svc-id {
    type string;
    description
      "Defines the type of service component identifier.";
  }

  typedef ccm-priority-type {
    type uint8 {
      range "0..7";
    }
    description
      "A 3-bit priority value to be used in the VLAN tag,
       if present in the transmitted frame.";
  }

  typedef control-mode {
    type enumeration {
      enum peer {
        description
          "'peer' mode, i.e., participate in the protocol towards
           the CE.  Peering is common for LACP and the Ethernet
           Local Management Interface (E-LMI) and, occasionally,
           for LLDP.  For VPLSs and VPWSs, the subscriber can also
           request that the SP peer enable spanning tree.";
      }
      enum tunnel {
        description
          "'tunnel' mode, i.e., pass to the egress or destination
           site.  For EPLs, the expectation is that L2CP frames are
           tunneled.";
      }
      enum discard {
        description
          "'discard' mode, i.e., discard the frame.";

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      }
    }
    description
      "Defines the type of control mode on L2CP protocols.";
  }

  typedef neg-mode {
    type enumeration {
      enum full-duplex {
        description
          "Defines full-duplex mode.";
      }
      enum auto-neg {
        description
          "Defines auto-negotiation mode.";
      }
    }
    description
      "Defines the type of negotiation mode.";
  }

  identity site-network-access-type {
    description
      "Base identity for the site-network-access type.";
  }

  identity point-to-point {
    base site-network-access-type;
    description
      "Identity for a point-to-point connection.";
  }

  identity multipoint {
    base site-network-access-type;
    description
      "Identity for a multipoint connection, e.g.,
       an Ethernet broadcast segment.";
  }

  identity tag-type {
    description
      "Base identity from which all tag types are derived.";
  }

  identity c-vlan {
    base tag-type;
    description
      "A CVLAN tag, normally using the 0x8100 Ethertype.";

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  }

  identity s-vlan {
    base tag-type;
    description
      "An SVLAN tag.";
  }

  identity c-s-vlan {
    base tag-type;
    description
      "Using both a CVLAN tag and an SVLAN tag.";
  }

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

  identity ssm-tree-type {
    base multicast-tree-type;
    description
      "Identity for the Source-Specific Multicast (SSM) tree type.";
    reference "RFC 8299: YANG Data Model for L3VPN Service Delivery";
  }

  identity asm-tree-type {
    base multicast-tree-type;
    description
      "Identity for the Any-Source Multicast (ASM) tree type.";
    reference "RFC 8299: YANG Data Model for L3VPN Service Delivery";
  }

  identity bidir-tree-type {
    base multicast-tree-type;
    description
      "Identity for the bidirectional tree type.";
    reference "RFC 8299: YANG Data Model for L3VPN Service Delivery";
  }

  identity multicast-gp-address-mapping {
    description
      "Identity for mapping type.";
  }

  identity static-mapping {
    base multicast-gp-address-mapping;
    description

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      "Identity for static mapping, i.e., attach the interface
       to the multicast group as a static member.";
  }

  identity dynamic-mapping {
    base multicast-gp-address-mapping;
    description
      "Identity for dynamic mapping, i.e., an interface was added
       to the multicast group as a result of snooping.";
  }

  identity tf-type {
    description
      "Identity for the traffic type.";
  }

  identity multicast-traffic {
    base tf-type;
    description
      "Identity for multicast traffic.";
  }

  identity broadcast-traffic {
    base tf-type;
    description
      "Identity for broadcast traffic.";
  }

  identity unknown-unicast-traffic {
    base tf-type;
    description
      "Identity for unknown unicast traffic.";
  }

  identity encapsulation-type {
    description
      "Identity for the encapsulation type.";
  }

  identity ethernet {
    base encapsulation-type;
    description
      "Identity for Ethernet type.";
  }

  identity vlan {
    base encapsulation-type;
    description

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      "Identity for the VLAN type.";
  }

  identity carrierscarrier-type {
    description
      "Identity of the CsC type.";
  }

  identity ldp {
    base carrierscarrier-type;
    description
      "Use LDP as the signaling protocol
       between the PE and the CE.";
  }

  identity bgp {
    base carrierscarrier-type;
    description
      "Use BGP (as per RFC 8277) as the signaling protocol
       between the PE and the CE.
       In this case, BGP must also be configured as
       the routing protocol.";
  }

  identity eth-inf-type {
    description
      "Identity of the Ethernet interface type.";
  }

  identity tagged {
    base eth-inf-type;
    description
      "Identity of the tagged interface type.";
  }

  identity untagged {
    base eth-inf-type;
    description
      "Identity of the untagged interface type.";
  }

  identity lag {
    base eth-inf-type;
    description
      "Identity of the LAG interface type.";
  }

  identity bw-type {

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    description
      "Identity of the bandwidth type.";
  }

  identity bw-per-cos {
    base bw-type;
    description
      "Bandwidth is per CoS.";
  }

  identity bw-per-port {
    base bw-type;
    description
      "Bandwidth is per site network access.";
  }

  identity bw-per-site {
    base bw-type;
    description
      "Bandwidth is per site.  It is applicable to
       all the site network accesses within the site.";
  }

  identity bw-per-svc {
    base bw-type;
    description
      "Bandwidth is per VPN service.";
  }

  identity site-vpn-flavor {
    description
      "Base identity for the site VPN service flavor.";
  }

  identity site-vpn-flavor-single {
    base site-vpn-flavor;
    description
      "Identity for the site VPN service flavor.
       Used when the site belongs to only one VPN.";
  }

  identity site-vpn-flavor-multi {
    base site-vpn-flavor;
    description
      "Identity for the site VPN service flavor.
       Used when a logical connection of a site
       belongs to multiple VPNs.";
  }

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  identity site-vpn-flavor-nni {
    base site-vpn-flavor;
    description
      "Identity for the site VPN service flavor.
       Used to describe an NNI option A connection.";
  }

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

  identity vpws {
    base service-type;
    description
      "Point-to-point Virtual Private Wire Service (VPWS)
       service type.";
  }

  identity pwe3 {
    base service-type;
    description
      "Pseudowire Emulation Edge to Edge (PWE3) service type.";
  }

  identity ldp-l2tp-vpls {
    base service-type;
    description
      "LDP-based or L2TP-based multipoint Virtual Private LAN
       Service (VPLS) service type.  This VPLS uses LDP-signaled
       Pseudowires or L2TP-signaled Pseudowires.";
  }

  identity bgp-vpls {
    base service-type;
    description
      "BGP-based multipoint VPLS service type.  This VPLS uses a
       BGP control plane as described in RFCs 4761 and 6624.";
  }

  identity vpws-evpn {
    base service-type;
    description
      "VPWS service type using Ethernet VPNs (EVPNs)
       as specified in RFC 7432.";
  }

  identity pbb-evpn {

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    base service-type;
    description
      "Provider Backbone Bridge (PBB) service type using
       EVPNs as specified in RFC 7432.";
  }

  identity bundling-type {
    description
      "The base identity for the bundling type.  It supports
       multiple CE-VLANs associated with an L2VPN service or
       all CE-VLANs associated with an L2VPN service.";
  }

  identity multi-svc-bundling {
    base bundling-type;
    description
      "Identity for multi-service bundling, i.e.,
       multiple CE-VLAN IDs can be associated with an
       L2VPN service at a site.";
  }

  identity one2one-bundling {
    base bundling-type;
    description
      "Identity for one-to-one service bundling, i.e.,
       each L2VPN can be associated with only one CE-VLAN ID
       at a site.";
  }

  identity all2one-bundling {
    base bundling-type;
    description
      "Identity for all-to-one bundling, i.e., all CE-VLAN IDs
       are mapped to one L2VPN service.";
  }

  identity color-id {
    description
      "Base identity of the color ID.";
  }

  identity color-id-cvlan {
    base color-id;
    description
      "Identity of the color ID based on a CVLAN.";
  }

  identity cos-id {

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    description
      "Identity of the CoS ID.";
  }

  identity cos-id-pcp {
    base cos-id;
    description
      "Identity of the CoS ID based on the
       Port Control Protocol (PCP).";
  }

  identity cos-id-dscp {
    base cos-id;
    description
      "Identity of the CoS ID based on DSCP.";
  }

  identity color-type {
    description
      "Identity of color types.";
  }

  identity green {
    base color-type;
    description
      "Identity of the 'green' color type.";
  }

  identity yellow {
    base color-type;
    description
      "Identity of the 'yellow' color type.";
  }

  identity red {
    base color-type;
    description
      "Identity of the 'red' color type.";
  }

  identity policing {
    description
      "Identity of the type of policing applied.";
  }

  identity one-rate-two-color {
    base policing;
    description

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      "Identity of one-rate, two-color (1R2C).";
  }

  identity two-rate-three-color {
    base policing;
    description
      "Identity of two-rate, three-color (2R3C).";
  }

  identity bum-type {
    description
      "Identity of the BUM type.";
  }

  identity broadcast {
    base bum-type;
    description
      "Identity of broadcast.";
  }

  identity unicast {
    base bum-type;
    description
      "Identity of unicast.";
  }

  identity multicast {
    base bum-type;
    description
      "Identity of multicast.";
  }

  identity loop-prevention-type {
    description
      "Identity of loop prevention.";
  }

  identity shut {
    base loop-prevention-type;
    description
      "Identity of shut protection.";
  }

  identity trap {
    base loop-prevention-type;
    description
      "Identity of trap protection.";
  }

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  identity lacp-state {
    description
      "Identity of the LACP state.";
  }

  identity lacp-on {
    base lacp-state;
    description
      "Identity of LACP on.";
  }

  identity lacp-off {
    base lacp-state;
    description
      "Identity of LACP off.";
  }

  identity lacp-mode {
    description
      "Identity of the LACP mode.";
  }

  identity lacp-passive {
    base lacp-mode;
    description
      "Identity of LACP passive.";
  }

  identity lacp-active {
    base lacp-mode;
    description
      "Identity of LACP active.";
  }

  identity lacp-speed {
    description
      "Identity of the LACP speed.";
  }

  identity lacp-fast {
    base lacp-speed;
    description
      "Identity of LACP fast.";
  }

  identity lacp-slow {
    base lacp-speed;
    description

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      "Identity of LACP slow.";
  }

  identity bw-direction {
    description
      "Identity for the bandwidth direction.";
  }

  identity input-bw {
    base bw-direction;
    description
      "Identity for the input bandwidth.";
  }

  identity output-bw {
    base bw-direction;
    description
      "Identity for the output bandwidth.";
  }

  identity management {
    description
      "Base identity for the site management scheme.";
  }

  identity co-managed {
    base management;
    description
      "Identity for a co-managed site.";
  }

  identity customer-managed {
    base management;
    description
      "Identity for a customer-managed site.";
  }

  identity provider-managed {
    base management;
    description
      "Identity for a provider-managed site.";
  }

  identity address-family {
    description
      "Identity for an address family.";
  }

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  identity ipv4 {
    base address-family;
    description
      "Identity for an IPv4 address family.";
  }

  identity ipv6 {
    base address-family;
    description
      "Identity for an IPv6 address family.";
  }

  identity vpn-topology {
    description
      "Base identity for the VPN topology.";
  }

  identity any-to-any {
    base vpn-topology;
    description
      "Identity for the any-to-any VPN topology.";
  }

  identity hub-spoke {
    base vpn-topology;
    description
      "Identity for the Hub-and-Spoke VPN topology.";
  }

  identity hub-spoke-disjoint {
    base vpn-topology;
    description
      "Identity for the Hub-and-Spoke VPN topology,
       where Hubs cannot communicate with each other.";
  }

  identity site-role {
    description
      "Base identity for a site type.";
  }

  identity any-to-any-role {
    base site-role;
    description
      "Site in an any-to-any L2VPN.";
  }

  identity spoke-role {

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    base site-role;
    description
      "Spoke site in a Hub-and-Spoke L2VPN.";
  }

  identity hub-role {
    base site-role;
    description
      "Hub site in a Hub-and-Spoke L2VPN.";
  }

  identity pm-type {
    description
      "Performance-monitoring type.";
  }

  identity loss {
    base pm-type;
    description
      "Loss measurement.";
  }

  identity delay {
    base pm-type;
    description
      "Delay measurement.";
  }

  identity fault-alarm-defect-type {
    description
      "Indicates the alarm-priority defect (i.e., the
       lowest-priority defect that is allowed to
       generate a fault alarm).";
  }

  identity remote-rdi {
    base fault-alarm-defect-type;
    description
      "Indicates the aggregate health
       of the Remote MEPs.";
  }

  identity remote-mac-error {
    base fault-alarm-defect-type;
    description
      "Indicates that one or more of the Remote MEPs are
       reporting a failure in their Port Status TLVs or
       Interface Status TLVs.";

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  }

  identity remote-invalid-ccm {
    base fault-alarm-defect-type;
    description
      "Indicates that at least one of the Remote MEP
       state machines is not receiving valid
       Continuity Check Messages (CCMs) from its Remote MEP.";
  }

  identity invalid-ccm {
    base fault-alarm-defect-type;
    description
      "Indicates that one or more invalid CCMs have been
       received and that a period of time 3.5 times the length
       of those CCMs' transmission intervals has not yet expired.";
  }

  identity cross-connect-ccm {
    base fault-alarm-defect-type;
    description
      "Indicates that one or more cross-connect CCMs have been
       received and that 3.5 times the period of at least one of
       those CCMs' transmission intervals has not yet expired.";
  }

  identity frame-delivery-mode {
    description
      "Delivery types.";
  }

  identity discard {
    base frame-delivery-mode;
    description
      "Service frames are discarded.";
  }

  identity unconditional {
    base frame-delivery-mode;
    description
      "Service frames are unconditionally delivered to the
       destination site.";
  }

  identity unknown-discard {
    base frame-delivery-mode;
    description
      "Service frames are conditionally delivered to the

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       destination site.  Packets with unknown destination addresses
       will be discarded.";
  }

  identity placement-diversity {
    description
      "Base identity for site placement constraints.";
  }

  identity bearer-diverse {
    base placement-diversity;
    description
      "Identity for bearer diversity.
       The bearers should not use common elements.";
  }

  identity pe-diverse {
    base placement-diversity;
    description
      "Identity for PE diversity.";
  }

  identity pop-diverse {
    base placement-diversity;
    description
      "Identity for POP diversity.";
  }

  identity linecard-diverse {
    base placement-diversity;
    description
      "Identity for linecard diversity.";
  }

  identity same-pe {
    base placement-diversity;
    description
      "Identity for having sites connected on the same PE.";
  }

  identity same-bearer {
    base placement-diversity;
    description
      "Identity for having sites connected using the same bearer.";
  }

  identity tagged-inf-type {
    description

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      "Identity for the tagged interface type.";
  }

  identity priority-tagged {
    base tagged-inf-type;
    description
      "Identity for the priority-tagged interface.";
  }

  identity qinq {
    base tagged-inf-type;
    description
      "Identity for the QinQ tagged interface.";
  }

  identity dot1q {
    base tagged-inf-type;
    description
      "Identity for the dot1Q VLAN tagged interface.";
  }

  identity qinany {
    base tagged-inf-type;
    description
      "Identity for the QinAny tagged interface.";
  }

  identity vxlan {
    base tagged-inf-type;
    description
      "Identity for the VXLAN tagged interface.";
  }

  identity provision-model {
    description
      "Base identity for the provision model.";
  }

  identity single-side-provision {
    description
      "Identity for single-sided provisioning with discovery.";
  }

  identity doubled-side-provision {
    description
      "Identity for double-sided provisioning.";
  }

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  identity mac-learning-mode {
    description
      "MAC learning mode.";
  }

  identity data-plane {
    base mac-learning-mode;
    description
      "User MAC addresses are learned through ARP broadcast.";
  }

  identity control-plane {
    base mac-learning-mode;
    description
      "User MAC addresses are advertised through EVPN-BGP.";
  }

  identity vpn-policy-filter-type {
    description
      "Base identity for the filter type.";
  }

  identity lan {
    base vpn-policy-filter-type;
    description
      "Identity for a LAN tag filter type.";
  }

  identity mac-action {
    description
      "Base identity for a MAC action.";
  }

  identity drop {
    base mac-action;
    description
      "Identity for dropping a packet.";
  }

  identity flood {
    base mac-action;
    description
      "Identity for packet flooding.";
  }

  identity warning {
    base mac-action;
    description

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      "Identity for sending a warning log message.";
  }

  identity qos-profile-direction {
    description
      "Base identity for the QoS-profile direction.";
   }

  identity site-to-wan {
    base qos-profile-direction;
    description
      "Identity for the site-to-WAN direction.";
  }

  identity wan-to-site {
    base qos-profile-direction;
    description
      "Identity for the WAN-to-site direction.";
  }

  identity bidirectional {
    base qos-profile-direction;
    description
      "Identity for both the WAN-to-site direction
       and the site-to-WAN direction.";
  }

  identity vxlan-peer-mode {
    description
      "Base identity for the VXLAN peer mode.";
  }

  identity static-mode {
    base vxlan-peer-mode;
    description
      "Identity for VXLAN access in the static mode.";
  }

  identity bgp-mode {
    base vxlan-peer-mode;
    description
      "Identity for VXLAN access by BGP EVPN learning.";
  }

  identity customer-application {
    description
      "Base identity for a customer application.";
  }

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  identity web {
    base customer-application;
    description
      "Identity for a web application (e.g., HTTP, HTTPS).";
  }

  identity mail {
    base customer-application;
    description
      "Identity for a mail application.";
  }

  identity file-transfer {
    base customer-application;
    description
      "Identity for a file-transfer application
       (e.g., FTP, SFTP).";
  }

  identity database {
    base customer-application;
    description
      "Identity for a database application.";
  }

  identity social {
    base customer-application;
    description
      "Identity for a social-network application.";
  }

  identity games {
    base customer-application;
    description
      "Identity for a gaming application.";
  }

  identity p2p {
    base customer-application;
    description
      "Identity for a peer-to-peer application.";
  }

  identity network-management {
    base customer-application;
    description
      "Identity for a management application
       (e.g., Telnet, syslog, SNMP).";

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  }

  identity voice {
    base customer-application;
    description
      "Identity for a voice application.";
  }

  identity video {
    base customer-application;
    description
      "Identity for a videoconference application.";
  }

  identity embb {
    base customer-application;
    description
      "Identity for the enhanced Mobile Broadband (eMBB)
       application.  Note that the eMBB application
       requires strict threshold values for a wide variety
       of network performance parameters (e.g., data rate,
       latency, loss rate, reliability).";
  }

  identity urllc {
    base customer-application;
    description
      "Identity for the Ultra-Reliable and Low Latency
       Communications (URLLC) application.  Note that the
       URLLC application requires strict threshold values for
       a wide variety of network performance parameters
       (e.g., latency, reliability).";
  }

  identity mmtc {
    base customer-application;
    description
      "Identity for the massive Machine Type
       Communications (mMTC) application.  Note that the
       mMTC application requires strict threshold values for
       a wide variety of network performance parameters
       (e.g., data rate, latency, loss rate, reliability).";
  }

  grouping site-acl {
    container access-control-list {
      if-feature "acl";
      list mac {

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        key "mac-address";
        leaf mac-address {
          type yang:mac-address;
          description
            "MAC addresses.";
        }
        description
          "List of MAC addresses.";
      }
      description
        "Container for the ACL.";
    }
    description
      "Grouping that defines the ACL.";
  }

  grouping site-bum {
    container broadcast-unknown-unicast-multicast {
      if-feature "bum";
      leaf multicast-site-type {
        type enumeration {
          enum receiver-only {
            description
              "The site only has receivers.";
          }
          enum source-only {
            description
              "The site only has sources.";
          }
          enum source-receiver {
            description
              "The site has both sources and receivers.";
          }
        }
        default "source-receiver";
        description
          "Type of multicast site.";
      }
      list multicast-gp-address-mapping {
        key "id";
        leaf id {
          type uint16;
          description
            "Unique identifier for the mapping.";
        }
        leaf vlan-id {
          type uint16 {
            range "0..1024";

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          }
          mandatory true;
          description
            "The VLAN ID of the multicast group.
             The range of the 12-bit VLAN ID is 0 to 1024.";
        }
        leaf mac-gp-address {
          type yang:mac-address;
          mandatory true;
          description
            "The MAC address of the multicast group.";
        }
        leaf port-lag-number {
          type uint32;
          description
            "The ports/LAGs belonging to the multicast group.";
        }
        description
          "List of port-to-group mappings.";
      }
      leaf bum-overall-rate {
        type uint64;
        units "bps";
        description
          "Overall rate for BUM.";
      }
      list bum-rate-per-type {
        key "type";
        leaf type {
          type identityref {
            base bum-type;
          }
          description
            "BUM type.";
        }
        leaf rate {
          type uint64;
          units "bps";
          description
            "Rate for BUM.";
        }
        description
          "List of limit rates for the BUM type.";
      }
      description
        "Container of BUM configurations.";
    }
    description

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      "Grouping for BUM.";
  }

  grouping site-mac-loop-prevention {
    container mac-loop-prevention {
      if-feature "mac-loop-prevention";
      leaf protection-type {
        type identityref {
          base loop-prevention-type;
        }
        default "trap";
        description
          "Protection type.  By default, the protection
           type is 'trap'.";
      }
      leaf frequency {
        type uint32;
        default "5";
        description
          "The number of times to detect MAC duplication, where
           a 'duplicate MAC address' situation has occurred and
           the duplicate MAC address has been added to a list of
           duplicate MAC addresses.  By default, the number of
           times is 5.";
      }
      leaf retry-timer {
        type uint32;
        units "seconds";
        description
          "The retry timer.  When the retry timer expires,
           the duplicate MAC address will be flushed from
           the MAC-VRF.";
      }
      description
        "Container of MAC loop-prevention parameters.";
    }
    description
      "Grouping for MAC loop prevention.";
  }

  grouping site-service-qos-profile {
    container qos {
      if-feature "qos";
      container qos-classification-policy {
        list rule {
          key "id";
          ordered-by user;
          leaf id {

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            type string;
            description
              "A description identifying the QoS classification
               policy rule.";
          }
          choice match-type {
            default "match-flow";
            case match-flow {
              container match-flow {
                leaf dscp {
                  type inet:dscp;
                  description
                    "DSCP value.";
                }
                leaf dot1q {
                  type uint16;
                  description
                    "802.1Q matching.  It is a VLAN tag added into
                     a frame.";
                }
                leaf pcp {
                  type uint8 {
                    range "0..7";
                  }
                  description
                    "PCP value.";
                }
                leaf src-mac {
                  type yang:mac-address;
                  description
                    "Source MAC.";
                }
                leaf dst-mac {
                  type yang:mac-address;
                  description
                    "Destination MAC.";
                }
                leaf color-type {
                  type identityref {
                    base color-type;
                  }
                  description
                    "Color types.";
                }
                leaf-list target-sites {
                  if-feature "target-sites";
                  type svc-id;
                  description

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                    "Identifies a site as a traffic destination.";
                }
                leaf any {
                  type empty;
                  description
                    "Allow all.";
                }
                leaf vpn-id {
                  type svc-id;
                  description
                    "Reference to the target VPN.";
                }
                description
                  "Describes flow-matching criteria.";
              }
            }
            case match-application {
              leaf match-application {
                type identityref {
                  base customer-application;
                }
                description
                  "Defines the application to match.";
              }
            }
            description
              "Choice for classification.";
          }
          leaf target-class-id {
            type string;
            description
              "Identification of the CoS.
               This identifier is internal to the
               administration.";
          }
          description
            "List of marking rules.";
        }
        description
          "Configuration of the traffic classification policy.";
      }
      container qos-profile {
        choice qos-profile {
          description
            "Choice for the QoS profile.
             Can be a standard profile or a customized profile.";
          case standard {
            description

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              "Standard QoS profile.";
            leaf profile {
              type leafref {
                path "/l2vpn-svc/vpn-profiles/"
                   + "valid-provider-identifiers/"
                   + "qos-profile-identifier";
              }
              description
                "QoS profile to be used.";
            }
          }
          case custom {
            description
              "Customized QoS profile.";
            container classes {
              if-feature "qos-custom";
              list class {
                key "class-id";
                leaf class-id {
                  type string;
                  description
                    "Identification of the CoS.  This identifier is
                     internal to the administration.";
                }
                leaf direction {
                  type identityref {
                    base qos-profile-direction;
                  }
                  default "bidirectional";
                  description
                    "The direction in which the QoS profile is
                     applied.  By default, the direction is
                     bidirectional.";
                }
                leaf policing {
                  type identityref {
                    base policing;
                  }
                  default "one-rate-two-color";
                  description
                    "The policing type can be either one-rate,
                     two-color (1R2C) or two-rate, three-color
                     (2R3C).  By default, the policing type is
                     'one-rate-two-color'.";
                }
                leaf byte-offset {
                  type uint16;
                  description

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                    "Number of bytes in the service frame header
                     that are excluded from the QoS calculation
                     (e.g., extra VLAN tags).";
                }
                container frame-delay {
                  choice flavor {
                    case lowest {
                      leaf use-lowest-latency {
                        type empty;
                        description
                          "The traffic class should use the path
                           with the lowest delay.";
                      }
                    }
                    case boundary {
                      leaf delay-bound {
                        type uint16;
                        units "milliseconds";
                        description
                          "The traffic class should use a path
                           with a defined maximum delay.";
                      }
                    }
                    description
                      "Delay constraint on the traffic class.";
                  }
                  description
                    "Delay constraint on the traffic class.";
                }
                container frame-jitter {
                  choice flavor {
                    case lowest {
                      leaf use-lowest-jitter {
                        type empty;
                        description
                          "The traffic class should use the path
                           with the lowest jitter.";
                      }
                    }
                    case boundary {
                      leaf delay-bound {
                        type uint32;
                        units "microseconds";
                        description
                          "The traffic class should use a path
                           with a defined maximum jitter.";
                      }
                    }

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                    description
                      "Jitter constraint on the traffic class.";
                  }
                  description
                    "Jitter constraint on the traffic class.";
                }
                container frame-loss {
                  leaf rate {
                    type decimal64 {
                      fraction-digits 2;
                      range "0..100";
                    }
                    units "percent";
                    description
                      "Frame loss rate constraint on the traffic
                       class.";
                  }
                  description
                    "Container for frame loss rate.";
                }
                container bandwidth {
                  leaf guaranteed-bw-percent {
                    type decimal64 {
                      fraction-digits 5;
                      range "0..100";
                    }
                    units "percent";
                    mandatory true;
                    description
                      "Used to define the guaranteed bandwidth
                       as a percentage of the available service
                       bandwidth.";
                  }
                  leaf end-to-end {
                    type empty;
                    description
                      "Used if the bandwidth reservation
                       must be done on the MPLS network too.";
                  }
                  description
                    "Bandwidth constraint on the traffic class.";
                }
                description
                  "List of CoS entries.";
              }
              description
                "Container for list of CoS entries.";
            }

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          }
        }
        description
          "Qos profile configuration.";
      }
      description
        "QoS configuration.";
    }
    description
      "Grouping that defines QoS parameters for a site.";
  }

  grouping site-service-mpls {
    container carrierscarrier {
      if-feature "carrierscarrier";
      leaf signaling-type {
        type identityref {
          base carrierscarrier-type;
        }
        default "bgp";
        description
          "CsC.  By default, the signaling type is 'bgp'.";
      }
      description
        "Container for CsC.";
    }
    description
      "Grouping for CsC.";
  }

  container l2vpn-svc {
    container vpn-profiles {
      container valid-provider-identifiers {
        leaf-list cloud-identifier {
          if-feature "cloud-access";
          type string;
          description
            "Identification of the public cloud service or
             Internet service.  Local to each administration.";
        }
        leaf-list qos-profile-identifier {
          type string;
          description
            "Identification of the QoS profile to be used.
             Local to each administration.";
        }
        leaf-list bfd-profile-identifier {
          type string;

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          description
            "Identification of the SP BFD profile to be used.
             Local to each administration.";
        }
        leaf-list remote-carrier-identifier {
          type string;
          description
            "Identification of the remote carrier name to be used.
             It can be an L2VPN partner, data-center SP, or
             private CSP.  Local to each administration.";
        }
        nacm:default-deny-write;
        description
          "Container for valid provider identifiers.";
      }
      description
        "Container for VPN profiles.";
    }
    container vpn-services {
      list vpn-service {
        key "vpn-id";
        leaf vpn-id {
          type svc-id;
          description
            "Defines a service identifier.";
        }
        leaf vpn-svc-type {
          type identityref {
            base service-type;
          }
          default "vpws";
          description
            "Service type.  By default, the service type is 'vpws'.";
        }
        leaf customer-name {
          type string;
          description
            "Customer name.";
        }
        leaf svc-topo {
          type identityref {
            base vpn-topology;
          }
          default "any-to-any";
          description
            "Defines the service topology, e.g.,
             'any-to-any', 'hub-spoke'.";
        }

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        container cloud-accesses {
          if-feature "cloud-access";
          list cloud-access {
            key "cloud-identifier";
            leaf cloud-identifier {
              type leafref {
                path "/l2vpn-svc/vpn-profiles/"
                   + "valid-provider-identifiers"
                   + "/cloud-identifier";
              }
              description
                "Identification of the cloud service.
                 Local to each administration.";
            }
            choice list-flavor {
              case permit-any {
                leaf permit-any {
                  type empty;
                  description
                    "Allow all sites.";
                }
              }
              case deny-any-except {
                leaf-list permit-site {
                  type leafref {
                    path "/l2vpn-svc/sites/site/site-id";
                  }
                  description
                    "Site ID to be authorized.";
                }
              }
              case permit-any-except {
                leaf-list deny-site {
                  type leafref {
                    path "/l2vpn-svc/sites/site/site-id";
                  }
                  description
                    "Site ID to be denied.";
                }
              }
              description
                "Choice for cloud access policy.
                 By default, all sites in the L2VPN
                 MUST be authorized to access the cloud.";
            }
            description
              "Cloud access configuration.";
          }

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          description
            "Container for cloud access configurations.";
        }
        container frame-delivery {
          if-feature "bum";
          container customer-tree-flavors {
            leaf-list tree-flavor {
              type identityref {
                base multicast-tree-type;
              }
              description
                "Type of tree to be used.";
            }
            description
              "Types of trees used by the customer.";
          }
          container bum-deliveries {
            list bum-delivery {
              key "frame-type";
              leaf frame-type {
                type identityref {
                  base tf-type;
                }
                description
                  "Type of frame delivery.  It supports unicast
                   frame delivery, multicast frame delivery,
                   and broadcast frame delivery.";
              }
              leaf delivery-mode {
                type identityref {
                  base frame-delivery-mode;
                }
                default "unconditional";
                description
                  "Defines the frame delivery mode
                   ('unconditional' (default), 'conditional',
                   or 'discard').  By default, service frames are
                   unconditionally delivered to the destination site.";
              }
              description
                "List of frame delivery types and modes.";
            }
            description
              "Defines the frame delivery types and modes.";
          }
          leaf multicast-gp-port-mapping {
            type identityref {
              base multicast-gp-address-mapping;

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            }
            mandatory true;
            description
              "Describes the way in which each interface is
               associated with the multicast group.";
          }
          description
            "Multicast global parameters for the VPN service.";
        }
        container extranet-vpns {
          if-feature "extranet-vpn";
          list extranet-vpn {
            key "vpn-id";
            leaf vpn-id {
              type svc-id;
              description
                "Identifies the target VPN that the local VPN wants to
                 access.";
            }
            leaf local-sites-role {
              type identityref {
                base site-role;
              }
              default "any-to-any-role";
              description
                "Describes the role of the local sites in the target
                 VPN topology.  In the any-to-any VPN service topology,
                 the local sites must have the same role, which will be
                 'any-to-any-role'.  In the Hub-and-Spoke VPN service
                 topology or the Hub-and-Spoke-Disjoint VPN service
                 topology, the local sites must have a Hub role or a
                 Spoke role.";
            }
            description
              "List of extranet VPNs to which the local VPN
               is attached.";
          }
          description
            "Container for extranet VPN configurations.";
        }
        leaf ce-vlan-preservation {
          type boolean;
          mandatory true;
          description
            "Preserves the CE-VLAN ID from ingress to egress, i.e.,
             the CE-VLAN tag of the egress frame is identical to
             that of the ingress frame that yielded this
             egress service frame.  If all-to-one bundling within

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             a site is enabled, then preservation applies to all
             ingress service frames.  If all-to-one bundling is
             disabled, then preservation applies to tagged
             ingress service frames having CE-VLAN IDs 1 through 4094.";
        }
        leaf ce-vlan-cos-preservation {
          type boolean;
          mandatory true;
          description
            "CE VLAN CoS preservation.  The PCP bits in the CE-VLAN tag
             of the egress frame are identical to those of the
             ingress frame that yielded this egress service frame.";
        }
        leaf carrierscarrier {
          if-feature "carrierscarrier";
          type boolean;
          default "false";
          description
            "The VPN is using CsC, and so MPLS is required.";
        }
        description
          "List of VPN services.";
      }
      description
        "Container for VPN services.";
    }
    container sites {
      list site {
        key "site-id";
        leaf site-id {
          type string;
          description
            "Identifier of the site.";
        }
        leaf site-vpn-flavor {
          type identityref {
            base site-vpn-flavor;
          }
          default "site-vpn-flavor-single";
          description
            "Defines the way that the VPN multiplexing is
             done, e.g., whether the site belongs to
             a single VPN site or a multi-VPN site.  By
             default, the site belongs to a single VPN.";
        }
        container devices {
          when "derived-from-or-self(../management/type, "
             + "'l2vpn-svc:provider-managed') or "

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             + "derived-from-or-self(../management/type, "
             + "'l2vpn-svc:co-managed')" {
            description
              "Applicable only for a provider-managed or
               co-managed device.";
          }
          list device {
            key "device-id";
            leaf device-id {
              type string;
              description
                "Identifier for the device.";
            }
            leaf location {
              type leafref {
                path "../../../locations/location/location-id";
              }
              mandatory true;
              description
                "Location of the device.";
            }
            container management {
              when "derived-from-or-self(../../../management/type, "
                 + "'l2vpn-svc:co-managed')" {
                description
                  "Applicable only for a co-managed device.";
              }
              leaf transport {
                type identityref {
                  base address-family;
                }
                description
                  "Transport protocol or address family
                   used for management.";
              }
              leaf address {
                when '(../ transport)' {
                  description
                    "If the address family is specified, then the
                     address should also be specified.  If the
                     transport is not specified, then the address
                     should not be specified.";
                }
                type inet:ip-address;
                description
                  "Management address.";
              }
              description

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                "Management configuration.  Applicable only for a
                 co-managed device.";
            }
            description
              "List of devices requested by the customer.";
          }
          description
            "Device configurations.";
        }
        container management {
          leaf type {
            type identityref {
              base management;
            }
            mandatory true;
            description
              "Management type of the connection.";
          }
          description
            "Management configuration.";
        }
        container locations {
          list location {
            key "location-id";
            leaf location-id {
              type string;
              description
                "Location ID.";
            }
            leaf address {
              type string;
              description
                "Address (number and street) of the site.";
            }
            leaf postal-code {
              type string;
              description
                "Postal code of the site.  The format of 'postal-code'
                 is similar to the 'PC' (postal code) label format
                 defined in RFC 4119.";
            }
            leaf state {
              type string;
              description
                "State (region) of the site.  This leaf can also be used
                 to describe a region of a country that does not have
                 states.";
            }

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            leaf city {
              type string;
              description
                "City of the site.";
            }
            leaf country-code {
              type string;
              description
                "Country of the site.  The format of 'country-code' is
                 similar to the 'country' label defined in RFC 4119.";
            }
            description
              "List of locations.";
          }
          description
            "Location of the site.";
        }
        container site-diversity {
          if-feature "site-diversity";
          container groups {
            list group {
              key "group-id";
              leaf group-id {
                type string;
                description
                  "The group-id to which the site belongs.";
              }
              description
                "List of group-ids.";
            }
            description
              "Groups to which the site belongs.
               All site network accesses will inherit those group
               values.";
          }
          description
            "The type of diversity constraint.";
        }
        container vpn-policies {
          list vpn-policy {
            key "vpn-policy-id";
            leaf vpn-policy-id {
              type string;
              description
                "Unique identifier for the VPN policy.";
            }
            list entries {
              key "id";

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              leaf id {
                type string;
                description
                  "Unique identifier for the policy entry.";
              }
              container filters {
                list filter {
                  key "type";
                  ordered-by user;
                  leaf type {
                    type identityref {
                      base vpn-policy-filter-type;
                    }
                    description
                      "Type of VPN policy filter.";
                  }
                  leaf-list lan-tag {
                    when "derived-from-or-self(../type, "
                       + "'l2vpn-svc:lan')" {
                      description
                        "Only applies when the VPN policy filter is a
                         LAN tag filter.";
                    }
                    if-feature "lan-tag";
                    type uint32;
                    description
                      "List of Ethernet LAN tags to be matched.  An
                       Ethernet LAN tag identifies a particular
                       broadcast domain in a VPN.";
                  }
                  description
                    "List of filters used on the site.  This list can
                     be augmented.";
                }
                description
                  "If a more granular VPN attachment is necessary,
                   filtering can be used.  If used, it permits the
                   splitting of site LANs among multiple VPNs.  The
                   site LAN can be split based on either the LAN tag or
                   the LAN prefix.  If no filter is used, all the LANs
                   will be part of the same VPNs with the same role.";
              }
              list vpn {
                key "vpn-id";
                leaf vpn-id {
                  type leafref {
                    path "/l2vpn-svc/vpn-services/vpn-service/vpn-id";
                  }

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                  description
                    "Reference to an L2VPN.";
                }
                leaf site-role {
                  type identityref {
                    base site-role;
                  }
                  default "any-to-any-role";
                  description
                    "Role of the site in the L2VPN.";
                }
                description
                  "List of VPNs with which the LAN is associated.";
              }
              description
                "List of entries for an export policy.";
            }
            description
              "List of VPN policies.";
          }
          description
            "VPN policy.";
        }
        container service {
          uses site-service-qos-profile;
          uses site-service-mpls;
          description
            "Service parameters on the attachment.";
        }
        uses site-bum;
        uses site-mac-loop-prevention;
        uses site-acl;
        leaf actual-site-start {
          type yang:date-and-time;
          config false;
          description
            "This leaf is optional.  It indicates the date and time
             when the service at a particular site actually started.";
        }
        leaf actual-site-stop {
          type yang:date-and-time;
          config false;
          description
            "This leaf is optional.  It indicates the date and time
             when the service at a particular site actually stopped.";
        }
        leaf bundling-type {
          type identityref {

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            base bundling-type;
          }
          default "one2one-bundling";
          description
            "Bundling type.  By default, each L2VPN
             can be associated with only one
             CE-VLAN, i.e., one-to-one bundling is used.";
        }
        leaf default-ce-vlan-id {
          type uint32;
          mandatory true;
          description
            "Default CE VLAN ID set at the site level.";
        }
        container site-network-accesses {
          list site-network-access {
            key "network-access-id";
            leaf network-access-id {
              type string;
              description
                "Identifier of network access.";
            }
            leaf remote-carrier-name {
              when "derived-from-or-self(../../../site-vpn-flavor,"
                 + "'l2vpn-svc:site-vpn-flavor-nni')" {
                description
                  "Relevant when the site's VPN flavor is
                   'site-vpn-flavor-nni'.";
              }
              type leafref {
                path "/l2vpn-svc/vpn-profiles/"
                   + "valid-provider-identifiers"
                   + "/remote-carrier-identifier";
              }
              description
                "Remote carrier name.  The 'remote-carrier-name'
                 parameter must be configured only when
                 'site-vpn-flavor' is set to 'site-vpn-flavor-nni'.
                 If it is not set, it indicates that the customer
                 does not know the remote carrier's name
                 beforehand.";
            }
            leaf type {
              type identityref {
                base site-network-access-type;
              }
              default "point-to-point";
              description

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                "Describes the type of connection, e.g.,
                 point-to-point or multipoint.";
            }
            choice location-flavor {
              case location {
                when "derived-from-or-self(../../management/type, "
                   + "'l2vpn-svc:customer-managed')" {
                  description
                    "Applicable only for a customer-managed device.";
                }
                leaf location-reference {
                  type leafref {
                    path "../../../locations/location/location-id";
                  }
                  description
                    "Location of the site-network-access.";
                }
              }
              case device {
                when "derived-from-or-self(../../management/type, "
                   + "'l2vpn-svc:provider-managed') or "
                   + "derived-from-or-self(../../management/type, "
                   + "'l2vpn-svc:co-managed')" {
                  description
                    "Applicable only for a provider-managed
                     or co-managed device.";
                }
                leaf device-reference {
                  type leafref {
                    path "../../../devices/device/device-id";
                  }
                  description
                    "Identifier of the CE to use.";
                }
              }
              mandatory true;
              description
                "Choice of how to describe the site's location.";
            }
            container access-diversity {
              if-feature "site-diversity";
              container groups {
                list group {
                  key "group-id";
                  leaf group-id {
                    type string;
                    description
                      "Group-id to which the site belongs.";

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                  }
                  description
                    "List of group-ids.";
                }
                description
                  "Groups to which the site or site-network-access
                   belongs.";
              }
              container constraints {
                list constraint {
                  key "constraint-type";
                  leaf constraint-type {
                    type identityref {
                      base placement-diversity;
                    }
                    description
                      "The type of diversity constraint.";
                  }
                  container target {
                    choice target-flavor {
                      default "id";
                      case id {
                        list group {
                          key "group-id";
                          leaf group-id {
                            type string;
                            description
                              "The constraint will apply against this
                               particular group-id.";
                          }
                          description
                            "List of groups.";
                        }
                      }
                      case all-accesses {
                        leaf all-other-accesses {
                          type empty;
                          description
                            "The constraint will apply against all other
                             site network accesses of this site.";
                        }
                      }
                      case all-groups {
                        leaf all-other-groups {
                          type empty;
                          description
                            "The constraint will apply against all other
                             groups the customer is managing.";

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                        }
                      }
                      description
                        "Choice for the group definition.";
                    }
                    description
                      "The constraint will apply against
                       this list of groups.";
                  }
                  description
                    "List of constraints.";
                }
                description
                  "Constraints for placing this site network access.";
              }
              description
                "Diversity parameters.";
            }
            container bearer {
              container requested-type {
                if-feature "requested-type";
                leaf type {
                  type string;
                  description
                    "Type of requested bearer: Ethernet, ATM, Frame
                     Relay, IP Layer 2 transport, Frame Relay Data
                     Link Connection Identifier (DLCI), SONET/SDH,
                     PPP.";
                }
                leaf strict {
                  type boolean;
                  default "false";
                  description
                    "Defines whether the requested type is a preference
                     or a strict requirement.";
                }
                description
                  "Container for requested types.";
              }
              leaf always-on {
                if-feature "always-on";
                type boolean;
                default "true";
                description
                  "Request for an 'always-on' access type.
                   For example, this could mean no dial-in access
                   type.";
              }

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              leaf bearer-reference {
                if-feature "bearer-reference";
                type string;
                description
                  "An internal reference for the SP.";
              }
              description
                "Bearer-specific parameters.  To be augmented.";
            }
            container connection {
              leaf encapsulation-type {
                type identityref {
                  base encapsulation-type;
                }
                default "ethernet";
                description
                  "Encapsulation type.  By default, the
                   encapsulation type is set to 'ethernet'.";
              }
              leaf eth-inf-type {
                type identityref {
                  base eth-inf-type;
                }
                default "untagged";
                description
                  "Ethernet interface type.  By default, the
                   Ethernet interface type is set to 'untagged'.";
              }
              container tagged-interface {
                leaf type {
                  type identityref {
                    base tagged-inf-type;
                  }
                  default "priority-tagged";
                  description
                    "Tagged interface type.  By default,
                     the type of the tagged interface is
                     'priority-tagged'.";
                }
                container dot1q-vlan-tagged {
                  when "derived-from-or-self(../type, "
                     + "'l2vpn-svc:dot1q')" {
                    description
                      "Only applies when the type of the tagged
                       interface is 'dot1q'.";
                  }
                  if-feature "dot1q";
                  leaf tg-type {

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                    type identityref {
                      base tag-type;
                    }
                    default "c-vlan";
                    description
                      "Tag type.  By default, the tag type is
                       'c-vlan'.";
                  }
                  leaf cvlan-id {
                    type uint16;
                    mandatory true;
                    description
                      "VLAN identifier.";
                  }
                  description
                    "Tagged interface.";
                }
                container priority-tagged {
                  when "derived-from-or-self(../type, "
                     + "'l2vpn-svc:priority-tagged')" {
                    description
                      "Only applies when the type of the tagged
                       interface is 'priority-tagged'.";
                  }
                  leaf tag-type {
                    type identityref {
                      base tag-type;
                    }
                    default "c-vlan";
                    description
                      "Tag type.  By default, the tag type is
                       'c-vlan'.";
                  }
                  description
                    "Priority tagged.";
                }
                container qinq {
                  when "derived-from-or-self(../type, "
                     + "'l2vpn-svc:qinq')" {
                    description
                      "Only applies when the type of the tagged
                       interface is 'qinq'.";
                  }
                  if-feature "qinq";
                  leaf tag-type {
                    type identityref {
                      base tag-type;
                    }

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                    default "c-s-vlan";
                    description
                      "Tag type.  By default, the tag type is
                       'c-s-vlan'.";
                  }
                  leaf svlan-id {
                    type uint16;
                    mandatory true;
                    description
                      "SVLAN identifier.";
                  }
                  leaf cvlan-id {
                    type uint16;
                    mandatory true;
                    description
                      "CVLAN identifier.";
                  }
                  description
                    "QinQ.";
                }
                container qinany {
                  when "derived-from-or-self(../type, "
                     + "'l2vpn-svc:qinany')" {
                    description
                      "Only applies when the type of the tagged
                       interface is 'qinany'.";
                  }
                  if-feature "qinany";
                  leaf tag-type {
                    type identityref {
                      base tag-type;
                    }
                    default "s-vlan";
                    description
                      "Tag type.  By default, the tag type is
                       's-vlan'.";
                  }
                  leaf svlan-id {
                    type uint16;
                    mandatory true;
                    description
                      "SVLAN ID.";
                  }
                  description
                    "Container for QinAny.";
                }
                container vxlan {
                  when "derived-from-or-self(../type, "

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                     + "'l2vpn-svc:vxlan')" {
                    description
                      "Only applies when the type of the tagged
                       interface is 'vxlan'.";
                  }
                  if-feature "vxlan";
                  leaf vni-id {
                    type uint32;
                    mandatory true;
                    description
                      "VXLAN Network Identifier (VNI).";
                  }
                  leaf peer-mode {
                    type identityref {
                      base vxlan-peer-mode;
                    }
                    default "static-mode";
                    description
                      "Specifies the VXLAN access mode.  By default,
                       the peer mode is set to 'static-mode'.";
                  }
                  list peer-list {
                    key "peer-ip";
                    leaf peer-ip {
                      type inet:ip-address;
                      description
                        "Peer IP.";
                    }
                    description
                      "List of peer IP addresses.";
                  }
                  description
                    "QinQ.";
                }
                description
                  "Container for tagged interfaces.";
              }
              container untagged-interface {
                leaf speed {
                  type uint32;
                  units "mbps";
                  default "10";
                  description
                    "Port speed.";
                }
                leaf mode {
                  type neg-mode;
                  default "auto-neg";

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                  description
                    "Negotiation mode.";
                }
                leaf phy-mtu {
                  type uint32;
                  units "bytes";
                  description
                    "PHY MTU.";
                }
                leaf lldp {
                  type boolean;
                  default "false";
                  description
                    "LLDP.  Indicates that LLDP is supported.";
                }
                container oam-802.3ah-link {
                  if-feature "oam-3ah";
                  leaf enabled {
                    type boolean;
                    default "false";
                    description
                      "Indicates whether or not to support
                       OAM 802.3ah links.";
                  }
                  description
                    "Container for OAM 802.3ah links.";
                }
                leaf uni-loop-prevention {
                  type boolean;
                  default "false";
                  description
                    "If this leaf is set to 'true', then the port
                     automatically goes down when a physical
                     loopback is detected.";
                }
                description
                  "Container of untagged interface attribute
                   configurations.";
              }
              container lag-interfaces {
                if-feature "lag-interface";
                list lag-interface {
                  key "index";
                  leaf index {
                    type string;
                    description
                      "LAG interface index.";
                  }

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                  container lacp {
                    if-feature "lacp";
                    leaf enabled {
                      type boolean;
                      default "false";
                      description
                        "LACP on/off.  By default, LACP is disabled.";
                    }
                    leaf mode {
                      type neg-mode;
                      description
                        "LACP mode.  LACP modes have active mode and
                         passive mode ('false').  'Active mode' means
                         initiating the auto-speed negotiation and
                         trying to form an Ethernet channel with the
                         other end.  'Passive mode' means not initiating
                         the negotiation but responding to LACP packets
                         initiated by the other end (e.g., full duplex
                         or half duplex).";
                    }
                    leaf speed {
                      type uint32;
                      units "mbps";
                      default "10";
                      description
                        "LACP speed.  By default, the LACP speed is 10
                         Mbps.";
                    }
                    leaf mini-link-num {
                      type uint32;
                      description
                        "Defines the minimum number of links that must
                         be active before the aggregating link is put
                         into service.";
                    }
                    leaf system-priority {
                      type uint16;
                      default "32768";
                      description
                        "Indicates the LACP priority for the system.
                         The range is from 0 to 65535.
                         The default is 32768.";
                    }
                    container micro-bfd {
                      if-feature "micro-bfd";
                      leaf enabled {
                        type enumeration {
                          enum on {

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                            description
                              "Micro-bfd on.";
                          }
                          enum off {
                            description
                              "Micro-bfd off.";
                          }
                        }
                        default "off";
                        description
                          "Micro-BFD on/off.  By default, micro-BFD
                           is set to 'off'.";
                      }
                      leaf interval {
                        type uint32;
                        units "milliseconds";
                        description
                          "BFD interval.";
                      }
                      leaf hold-timer {
                        type uint32;
                        units "milliseconds";
                        description
                          "BFD hold timer.";
                      }
                      description
                        "Container of micro-BFD configurations.";
                    }
                    container bfd {
                      if-feature "bfd";
                      leaf enabled {
                        type boolean;
                        default "false";
                        description
                          "BFD activation.  By default, BFD is not
                           activated.";
                      }
                      choice holdtime {
                        default "fixed";
                        case profile {
                          leaf profile-name {
                            type leafref {
                              path "/l2vpn-svc/vpn-profiles/"
                                 + "valid-provider-identifiers"
                                 + "/bfd-profile-identifier";
                            }
                            description
                              "SP well-known profile.";

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                          }
                          description
                            "SP well-known profile.";
                        }
                        case fixed {
                          leaf fixed-value {
                            type uint32;
                            units "milliseconds";
                            description
                              "Expected hold time expressed in
                               milliseconds.";
                          }
                        }
                        description
                          "Choice for the hold-time flavor.";
                      }
                      description
                        "Container for BFD.";
                    }
                    container member-links {
                      list member-link {
                        key "name";
                        leaf name {
                          type string;
                          description
                            "Member link name.";
                        }
                        leaf speed {
                          type uint32;
                          units "mbps";
                          default "10";
                          description
                            "Port speed.";
                        }
                        leaf mode {
                          type neg-mode;
                          default "auto-neg";
                          description
                            "Negotiation mode.";
                        }
                        leaf link-mtu {
                          type uint32;
                          units "bytes";
                          description
                            "Link MTU size.";
                        }
                        container oam-802.3ah-link {
                          if-feature "oam-3ah";

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                          leaf enabled {
                            type boolean;
                            default "false";
                            description
                              "Indicates whether OAM 802.3ah links are
                               supported.";
                          }
                          description
                            "Container for OAM 802.3ah links.";
                        }
                        description
                          "Member link.";
                      }
                      description
                        "Container of the member link list.";
                    }
                    leaf flow-control {
                      type boolean;
                      default "false";
                      description
                        "Flow control.  Indicates whether flow control
                         is supported.";
                    }
                    leaf lldp {
                      type boolean;
                      default "false";
                      description
                        "LLDP.  Indicates whether LLDP is supported.";
                    }
                    description
                      "LACP.";
                  }
                  description
                    "List of LAG interfaces.";
                }
                description
                  "Container of LAG interface attribute
                   configurations.";
              }
              list cvlan-id-to-svc-map {
                key "svc-id";
                leaf svc-id {
                  type leafref {
                    path "/l2vpn-svc/vpn-services/vpn-service/vpn-id";
                  }
                  description
                    "VPN service identifier.";
                }

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                list cvlan-id {
                  key "vid";
                  leaf vid {
                    type uint16;
                    description
                      "CVLAN ID.";
                  }
                  description
                    "List of CVLAN-ID-to-SVC-map configurations.";
                }
                description
                  "List of CVLAN-ID-to-L2VPN-service-map
                   configurations.";
              }
              container l2cp-control {
                if-feature "l2cp-control";
                leaf stp-rstp-mstp {
                  type control-mode;
                  description
                    "STP / Rapid STP (RSTP) / Multiple STP (MSTP)
                     protocol type applicable to all sites.";
                }
                leaf pause {
                  type control-mode;
                  description
                    "Pause protocol type applicable to all sites.";
                }
                leaf lacp-lamp {
                  type control-mode;
                  description
                    "LACP / Link Aggregation Marker Protocol (LAMP).";
                }
                leaf link-oam {
                  type control-mode;
                  description
                    "Link OAM.";
                }
                leaf esmc {
                  type control-mode;
                  description
                    "Ethernet Synchronization Messaging Channel
                     (ESMC).";
                }
                leaf l2cp-802.1x {
                  type control-mode;
                  description
                    "IEEE 802.1x.";
                }

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                leaf e-lmi {
                  type control-mode;
                  description
                    "E-LMI.";
                }
                leaf lldp {
                  type boolean;
                  description
                    "LLDP protocol type applicable to all sites.";
                }
                leaf ptp-peer-delay {
                  type control-mode;
                  description
                    "Precision Time Protocol (PTP) peer delay.";
                }
                leaf garp-mrp {
                  type control-mode;
                  description
                    "GARP/MRP.";
                }
                description
                  "Container of L2CP control configurations.";
              }
              container oam {
                if-feature "ethernet-oam";
                leaf md-name {
                  type string;
                  mandatory true;
                  description
                    "Maintenance domain name.";
                }
                leaf md-level {
                  type uint16 {
                    range "0..255";
                  }
                  mandatory true;
                  description
                    "Maintenance domain level.  The level may be
                     restricted in certain protocols (e.g.,
                     protocols in Layer 0 to Layer 7).";
                }
                list cfm-8021-ag {
                  if-feature "cfm";
                  key "maid";
                  leaf maid {
                    type string;
                    mandatory true;
                    description

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                      "Identifies a Maintenance Association (MA).";
                  }
                  leaf mep-id {
                    type uint32;
                    description
                      "Local Maintenance Entity Group End Point (MEP)
                       ID.  The non-existence of this leaf means
                       that no defects are to be reported.";
                  }
                  leaf mep-level {
                    type uint32;
                    description
                      "Defines the MEP level.  The non-existence of this
                       leaf means that no defects are to be reported.";
                  }
                  leaf mep-up-down {
                    type enumeration {
                      enum up {
                        description
                          "MEP up.";
                      }
                      enum down {
                        description
                          "MEP down.";
                      }
                    }
                    default "up";
                    description
                      "MEP up/down.  By default, MEP up is used.
                       The non-existence of this leaf means that
                       no defects are to be reported.";
                  }
                  leaf remote-mep-id {
                    type uint32;
                    description
                      "Remote MEP ID.  The non-existence of this leaf
                       means that no defects are to be reported.";
                  }
                  leaf cos-for-cfm-pdus {
                    type uint32;
                    description
                      "CoS for CFM PDUs.  The non-existence of this leaf
                       means that no defects are to be reported.";
                  }
                  leaf ccm-interval {
                    type uint32;
                    units "milliseconds";
                    default "10000";

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                    description
                      "CCM interval.  By default, the CCM interval is
                       10,000 milliseconds (10 seconds).";
                  }
                  leaf ccm-holdtime {
                    type uint32;
                    units "milliseconds";
                    default "35000";
                    description
                      "CCM hold time.  By default, the CCM hold time
                       is 3.5 times the CCM interval.";
                  }
                  leaf alarm-priority-defect {
                    type identityref {
                      base fault-alarm-defect-type;
                    }
                    default "remote-invalid-ccm";
                    description
                      "The lowest-priority defect that is
                       allowed to generate a fault alarm.  By default,
                       'fault-alarm-defect-type' is set to
                       'remote-invalid-ccm'.  The non-existence of
                       this leaf means that no defects are
                       to be reported.";
                  }
                  leaf ccm-p-bits-pri {
                    type ccm-priority-type;
                    description
                      "The priority parameter for CCMs transmitted by
                       the MEP.  The non-existence of this leaf means
                       that no defects are to be reported.";
                  }
                  description
                    "List of 802.1ag CFM attributes.";
                }
                list y-1731 {
                  if-feature "y-1731";
                  key "maid";
                  leaf maid {
                    type string;
                    mandatory true;
                    description
                      "Identifies an MA.";
                  }
                  leaf mep-id {
                    type uint32;
                    description
                      "Local MEP ID.  The non-existence of this leaf

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                       means that no measurements are to be reported.";
                  }
                  leaf type {
                    type identityref {
                      base pm-type;
                    }
                    default "delay";
                    description
                      "Performance-monitoring types.  By default, the
                       performance-monitoring type is set to 'delay'.
                       The non-existence of this leaf means that no
                       measurements are to be reported.";
                  }
                  leaf remote-mep-id {
                    type uint32;
                    description
                      "Remote MEP ID.  The non-existence of this
                       leaf means that no measurements are to be
                       reported.";
                  }
                  leaf message-period {
                    type uint32;
                    units "milliseconds";
                    default "10000";
                    description
                      "Defines the interval between Y.1731
                       performance-monitoring messages.  The message
                       period is expressed in milliseconds.";
                  }
                  leaf measurement-interval {
                    type uint32;
                    units "seconds";
                    description
                      "Specifies the measurement interval for
                       statistics.  The measurement interval is
                       expressed in seconds.";
                  }
                  leaf cos {
                    type uint32;
                    description
                      "CoS.  The non-existence of this leaf means that
                       no measurements are to be reported.";
                  }
                  leaf loss-measurement {
                    type boolean;
                    default "false";
                    description
                      "Indicates whether or not to enable loss

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                       measurement.  By default, loss
                       measurement is not enabled.";
                  }
                  leaf synthetic-loss-measurement {
                    type boolean;
                    default "false";
                    description
                      "Indicates whether or not to enable synthetic loss
                       measurement.  By default, synthetic loss
                       measurement is not enabled.";
                  }
                  container delay-measurement {
                    leaf enable-dm {
                      type boolean;
                      default "false";
                      description
                        "Indicates whether or not to enable delay
                         measurement.  By default, delay measurement
                         is not enabled.";
                    }
                    leaf two-way {
                      type boolean;
                      default "false";
                      description
                        "Indicates whether delay measurement is two-way
                         ('true') or one-way ('false').  By default,
                         one-way measurement is enabled.";
                    }
                    description
                      "Container for delay measurement.";
                  }
                  leaf frame-size {
                    type uint32;
                    units "bytes";
                    description
                      "Frame size.  The non-existence of this leaf
                       means that no measurements are to be reported.";
                  }
                  leaf session-type {
                    type enumeration {
                      enum proactive {
                        description
                          "Proactive mode.";
                      }
                      enum on-demand {
                        description
                          "On-demand mode.";
                      }

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                    }
                    default "on-demand";
                    description
                      "Session type.  By default, the session type
                       is 'on-demand'.  The non-existence of this
                       leaf means that no measurements are to be
                       reported.";
                  }
                  description
                    "List of configured Y-1731 instances.";
                }
                description
                  "Container for Ethernet Service OAM.";
              }
              description
                "Container for connection requirements.";
            }
            container availability {
              leaf access-priority {
                type uint32;
                default "100";
                description
                  "Access priority.  The higher the access-priority
                   value, the higher the preference will be for the
                   access in question.";
              }
              choice redundancy-mode {
                case single-active {
                  leaf single-active {
                    type empty;
                    description
                      "Single-active mode.";
                  }
                  description
                    "In single-active mode, only one node forwards
                     traffic to and from the Ethernet segment.";
                }
                case all-active {
                  leaf all-active {
                    type empty;
                    description
                      "All-active mode.";
                  }
                  description
                    "In all-active mode, all nodes can forward
                     traffic.";
                }
                description

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                  "Redundancy mode choice.";
              }
              description
                "Container of available optional configurations.";
            }
            container vpn-attachment {
              choice attachment-flavor {
                case vpn-id {
                  leaf vpn-id {
                    type leafref {
                      path "/l2vpn-svc/vpn-services/vpn-service/vpn-id";
                    }
                    description
                      "Reference to an L2VPN.  Referencing a vpn-id
                       provides an easy way to attach a particular
                       logical access to a VPN.  In this case,
                       the vpn-id must be configured.";
                  }
                  leaf site-role {
                    type identityref {
                      base site-role;
                    }
                    default "any-to-any-role";
                    description
                      "Role of the site in the L2VPN.  When referencing
                       a vpn-id, the site-role setting must be added to
                       express the role of the site in the target VPN
                       service topology.";
                  }
                }
                case vpn-policy-id {
                  leaf vpn-policy-id {
                    type leafref {
                      path "../../../../vpn-policies/vpn-policy/"
                         + "vpn-policy-id";
                    }
                    description
                      "Reference to a VPN policy.";
                  }
                }
                mandatory true;
                description
                  "Choice for the VPN attachment flavor.";
              }
              description
                "Defines the VPN attachment of a site.";
            }
            container service {

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              container svc-bandwidth {
                if-feature "input-bw";
                list bandwidth {
                  key "direction type";
                  leaf direction {
                    type identityref {
                      base bw-direction;
                    }
                    description
                      "Indicates the bandwidth direction.  It can be
                       the bandwidth download direction from the SP to
                       the site or the bandwidth upload direction from
                       the site to the SP.";
                  }
                  leaf type {
                    type identityref {
                      base bw-type;
                    }
                    description
                      "Bandwidth type.  By default, the bandwidth type
                       is set to 'bw-per-cos'.";
                  }
                  leaf cos-id {
                    when "derived-from-or-self(../type, "
                       + "'l2vpn-svc:bw-per-cos')" {
                      description
                        "Relevant when the bandwidth type is set to
                         'bw-per-cos'.";
                    }
                    type uint8;
                    description
                      "Identifier of the CoS, indicated by DSCP or a
                       CE-VLAN CoS (802.1p) value in the service frame.
                       If the bandwidth type is set to 'bw-per-cos',
                       the CoS ID MUST also be specified.";
                  }
                  leaf vpn-id {
                    when "derived-from-or-self(../type, "
                       + "'l2vpn-svc:bw-per-svc')" {
                      description
                        "Relevant when the bandwidth type is
                         set as bandwidth per VPN service.";
                    }
                    type svc-id;
                    description
                      "Identifies the target VPN.  If the bandwidth
                       type is set as bandwidth per VPN service, the
                       vpn-id MUST be specified.";

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                  }
                  leaf cir {
                    type uint64;
                    units "bps";
                    mandatory true;
                    description
                      "Committed Information Rate.  The maximum number
                       of bits that a port can receive or send over
                       an interface in one second.";
                  }
                  leaf cbs {
                    type uint64;
                    units "bps";
                    mandatory true;
                    description
                      "Committed Burst Size (CBS).  Controls the bursty
                       nature of the traffic.  Traffic that does not
                       use the configured Committed Information Rate
                       (CIR) accumulates credits until the credits
                       reach the configured CBS.";
                  }
                  leaf eir {
                    type uint64;
                    units "bps";
                    description
                      "Excess Information Rate (EIR), i.e., excess frame
                       delivery allowed that is not subject to an SLA.
                       The traffic rate can be limited by the EIR.";
                  }
                  leaf ebs {
                    type uint64;
                    units "bps";
                    description
                      "Excess Burst Size (EBS).  The bandwidth available
                       for burst traffic from the EBS is subject to the
                       amount of bandwidth that is accumulated during
                       periods when traffic allocated by the EIR
                       policy is not used.";
                  }
                  leaf pir {
                    type uint64;
                    units "bps";
                    description
                      "Peak Information Rate, i.e., maximum frame
                       delivery allowed.  It is equal to or less
                       than the sum of the CIR and the EIR.";
                  }
                  leaf pbs {

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                    type uint64;
                    units "bps";
                    description
                      "Peak Burst Size.  It is measured in bytes per
                       second.";
                  }
                  description
                    "List of bandwidth values (e.g., per CoS,
                     per vpn-id).";
                }
                description
                  "From the customer site's perspective, the service
                   input/output bandwidth of the connection or
                   download/upload bandwidth from the SP/site
                   to the site/SP.";
              }
              leaf svc-mtu {
                type uint16;
                units "bytes";
                mandatory true;
                description
                  "SVC MTU.  It is also known as the maximum
                   transmission unit or maximum frame size.  When
                   a frame is larger than the MTU, it is broken
                   down, or fragmented, into smaller pieces by
                   the network protocol to accommodate the MTU
                   of the network.  If CsC is enabled,
                   the requested svc-mtu leaf will refer to the
                   MPLS MTU and not to the link MTU.";
              }
              uses site-service-qos-profile;
              uses site-service-mpls;
              description
                "Container for services.";
            }
            uses site-bum;
            uses site-mac-loop-prevention;
            uses site-acl;
            container mac-addr-limit {
              if-feature "mac-addr-limit";
              leaf limit-number {
                type uint16;
                default "2";
                description
                  "Maximum number of MAC addresses learned from
                   the subscriber for a single service instance.
                   The default allowed maximum number of MAC
                   addresses is 2.";

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              }
              leaf time-interval {
                type uint32;
                units "seconds";
                default "300";
                description
                  "The aging time of the MAC address.  By default,
                   the aging time is set to 300 seconds.";
              }
              leaf action {
                type identityref {
                  base mac-action;
                }
                default "warning";
                description
                  "Specifies the action taken when the upper limit is
                   exceeded: drop the packet, flood the packet, or
                   simply send a warning log message.  By default,
                   the action is set to 'warning'.";
              }
              description
                "Container of MAC address limit configurations.";
            }
            description
              "List of site network accesses.";
          }
          description
            "Container of port configurations.";
        }
        description
          "List of sites.";
      }
      description
        "Container of site configurations.";
    }
    description
      "Container for L2VPN services.";
  }
}

<CODE ENDS>

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9.  Security Considerations

   The YANG module specified in this document defines a 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 NETCONF access control model [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.

   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:

   o  /l2vpn-svc/vpn-services/vpn-service

      The entries in the list above include all of the VPN service
      configurations to which the customer subscribes and will use to
      indirectly create or modify the PE and CE device configurations.
      Unexpected changes to these entries could lead to service
      disruptions and/or network misbehavior.

   o  /l2vpn-svc/sites/site

      The entries in the list above include the customer site
      configurations.  As noted in the previous paragraph, unexpected
      changes to these entries could lead to service disruptions 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:

   o  /l2vpn-svc/vpn-services/vpn-service

   o  /l2vpn-svc/sites/site

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   The entries in the lists above include customer-proprietary or
   confidential information, e.g., customer name, site location,
   services to which the customer subscribes.

   When an SP collaborates with multiple customers, it has to ensure
   that a given customer can only view and modify its (the customer's)
   own service information.

   The data model defines some security parameters that can be extended
   via augmentation as part of the customer service request; those
   parameters are described in Sections 5.12 and 5.13.

10.  IANA Considerations

   IANA has assigned a new URI from the "IETF XML Registry" [RFC3688].

      URI: urn:ietf:params:xml:ns:yang:ietf-l2vpn-svc
      Registrant Contact: The IESG
      XML: N/A; the requested URI is an XML namespace

   IANA has assigned a new YANG module name in the "YANG Module Names"
   registry [RFC6020].

      name: ietf-l2vpn-svc
      namespace: urn:ietf:params:xml:ns:yang:ietf-l2vpn-svc
      prefix: l2vpn-svc
      reference: RFC 8466

11.  References

11.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

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

   [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>.

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   [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>.

   [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>.

   [RFC6073]  Martini, L., Metz, C., Nadeau, T., Bocci, M., and M.
              Aissaoui, "Segmented Pseudowire", RFC 6073,
              DOI 10.17487/RFC6073, January 2011,
              <https://www.rfc-editor.org/info/rfc6073>.

   [RFC6074]  Rosen, E., Davie, B., Radoaca, V., and W. Luo,
              "Provisioning, Auto-Discovery, and Signaling in Layer 2
              Virtual Private Networks (L2VPNs)", RFC 6074,
              DOI 10.17487/RFC6074, January 2011,
              <https://www.rfc-editor.org/info/rfc6074>.

   [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>.

   [RFC6991]  Schoenwaelder, J., Ed., "Common YANG Data Types",
              RFC 6991, DOI 10.17487/RFC6991, July 2013,
              <https://www.rfc-editor.org/info/rfc6991>.

   [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>.

   [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>.

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   [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>.

   [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>.

   [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>.

   [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>.

   [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>.

   [W3C.REC-xml-20081126]
              Bray, T., Paoli, J., Sperberg-McQueen, M., Maler, E., and
              F. Yergeau, "Extensible Markup Language (XML) 1.0 (Fifth
              Edition)", World Wide Web Consortium Recommendation
              REC-xml-20081126, November 2008,
              <https://www.w3.org/TR/2008/REC-xml-20081126>.

11.2.  Informative References

   [EVPN-YANG]
              Brissette, P., Ed., Shah, H., Ed., Chen, I., Ed., Hussain,
              I., Ed., Tiruveedhula, K., Ed., and J. Rabadan, Ed., "Yang
              Data Model for EVPN", Work in Progress, draft-ietf-bess-
              evpn-yang-05, February 2018.

   [IEEE-802-1ag]
              IEEE, "802.1ag - 2007 - IEEE Standard for Local and
              Metropolitan Area Networks - Virtual Bridged Local Area
              Networks Amendment 5: Connectivity Fault Management",
              DOI 10.1109/IEEESTD.2007.4431836.

   [IEEE-802-1D]
              IEEE, "802.1D-2004 - IEEE Standard for Local and
              metropolitan area networks: Media Access Control (MAC)
              Bridges", DOI 10.1109/IEEESTD.2004.94569.

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   [IEEE-802-1Q]
              IEEE, "802.1Q - 2014 - IEEE Standard for Local and
              metropolitan area networks--Bridges and Bridged Networks",
              DOI 10.1109/IEEESTD.2014.6991462.

   [IEEE-802-3ah]
              IEEE, "802.3ah - 2004 - IEEE Standard for Information
              technology-- Local and metropolitan area networks-- Part
              3: CSMA/CD Access Method and Physical Layer Specifications
              Amendment: Media Access Control Parameters, Physical
              Layers, and Management Parameters for Subscriber Access
              Networks", DOI 10.1109/IEEESTD.2004.94617.

   [ITU-T-Y-1731]
              International Telecommunication Union, "Operations,
              administration and maintenance (OAM) functions and
              mechanisms for Ethernet-based networks",
              ITU-T Recommendation Y.1731, August 2015,
              <https://www.itu.int/rec/T-REC-Y.1731/en>.

   [MEF-6]    Metro Ethernet Forum, "Ethernet Services Definitions -
              Phase 2", April 2008, <https://mef.net/PDF_Documents/
              technical-specifications/MEF6-1.pdf>.

   [MPLS-L2VPN-YANG]
              Shah, H., Ed., Brissette, P., Ed., Chen, I., Ed., Hussain,
              I., Ed., Wen, B., Ed., and K. Tiruveedhula, Ed., "YANG
              Data Model for MPLS-based L2VPN", Work in Progress,
              draft-ietf-bess-l2vpn-yang-08, February 2018.

   [RFC4119]  Peterson, J., "A Presence-based GEOPRIV Location Object
              Format", RFC 4119, DOI 10.17487/RFC4119, December 2005,
              <https://www.rfc-editor.org/info/rfc4119>.

   [RFC6624]  Kompella, K., Kothari, B., and R. Cherukuri, "Layer 2
              Virtual Private Networks Using BGP for Auto-Discovery and
              Signaling", RFC 6624, DOI 10.17487/RFC6624, May 2012,
              <https://www.rfc-editor.org/info/rfc6624>.

   [RFC7130]  Bhatia, M., Ed., Chen, M., Ed., Boutros, S., Ed.,
              Binderberger, M., Ed., and J. Haas, Ed., "Bidirectional
              Forwarding Detection (BFD) on Link Aggregation Group (LAG)
              Interfaces", RFC 7130, DOI 10.17487/RFC7130, February
              2014, <https://www.rfc-editor.org/info/rfc7130>.

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   [RFC7209]  Sajassi, A., Aggarwal, R., Uttaro, J., Bitar, N.,
              Henderickx, W., and A. Isaac, "Requirements for Ethernet
              VPN (EVPN)", RFC 7209, DOI 10.17487/RFC7209, May 2014,
              <https://www.rfc-editor.org/info/rfc7209>.

   [RFC7348]  Mahalingam, M., Dutt, D., Duda, K., Agarwal, P., Kreeger,
              L., Sridhar, T., Bursell, M., and C. Wright, "Virtual
              eXtensible Local Area Network (VXLAN): A Framework for
              Overlaying Virtualized Layer 2 Networks over Layer 3
              Networks", RFC 7348, DOI 10.17487/RFC7348, August 2014,
              <https://www.rfc-editor.org/info/rfc7348>.

   [RFC7436]  Shah, H., Rosen, E., Le Faucheur, F., and G. Heron,
              "IP-Only LAN Service (IPLS)", RFC 7436,
              DOI 10.17487/RFC7436, January 2015,
              <https://www.rfc-editor.org/info/rfc7436>.

   [RFC8199]  Bogdanovic, D., Claise, B., and C. Moberg, "YANG Module
              Classification", RFC 8199, DOI 10.17487/RFC8199, July
              2017, <https://www.rfc-editor.org/info/rfc8199>.

   [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>.

Acknowledgements

   Thanks to Qin Wu and Adrian Farrel for facilitating work on the
   initial draft revisions of this document.  Thanks to Zonghe Huang,
   Wei Deng, and Xiaoling Song for their review of this document.

   Special thanks to Jan Lindblad for his careful review of the YANG.

   This document has drawn on the work of the L3SM Working Group as
   provided in [RFC8299].

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Authors' Addresses

   Bin Wen
   Comcast

   Email: bin_wen@comcast.com

   Giuseppe Fioccola (editor)
   Telecom Italia

   Email: giuseppe.fioccola@tim.it

   Chongfeng Xie
   China Telecom

   Email: xiechf.bri@chinatelecom.cn

   Luay Jalil
   Verizon

   Email: luay.jalil@verizon.com

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