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rfc:rfc8049

Internet Engineering Task Force (IETF) S. Litkowski Request for Comments: 8049 Orange Business Services Category: Standards Track L. Tomotaki ISSN: 2070-1721 Verizon

                                                              K. Ogaki
                                                      KDDI Corporation
                                                         February 2017
             YANG Data Model for L3VPN Service Delivery

Abstract

 This document defines a YANG data model that can be used for
 communication between customers and network operators and to deliver
 a Layer 3 provider-provisioned VPN service.  This document is limited
 to BGP PE-based VPNs as described in RFCs 4026, 4110, and 4364.  This
 model is intended to be instantiated at the management system to
 deliver the overall service.  It is not a configuration model to be
 used directly on network elements.  This model provides an abstracted
 view of the Layer 3 IP VPN service configuration components.  It will
 be up to the management system to take this model as input and use
 specific configuration models to configure the different network
 elements to deliver the service.  How the configuration of network
 elements is done is out of scope for this document.

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
 http://www.rfc-editor.org/info/rfc8049.

Litkowski, et al. Standards Track [Page 1] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

Copyright Notice

 Copyright (c) 2017 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
 (http://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
    1.2. Requirements Language ......................................5
    1.3. Tree Diagrams ..............................................5
 2. Acronyms ........................................................5
 3. Definitions .....................................................7
 4. Layer 3 IP VPN Service Model ....................................8
 5. Service Data Model Usage ........................................9
 6. Design of the Data Model .......................................10
    6.1. Features and Augmentation .................................18
    6.2. VPN Service Overview ......................................18
         6.2.1. VPN Service Topology ...............................18
                6.2.1.1. Route Target Allocation ...................19
                6.2.1.2. Any-to-Any ................................20
                6.2.1.3. Hub and Spoke .............................20
                6.2.1.4. Hub and Spoke Disjoint ....................21
         6.2.2. Cloud Access .......................................22
         6.2.3. Multicast Service ..................................24
         6.2.4. Extranet VPNs ......................................26
    6.3. Site Overview .............................................27
         6.3.1. Devices and Locations ..............................29
         6.3.2. Site Network Accesses ..............................30
                6.3.2.1. Bearer ....................................30
                6.3.2.2. Connection ................................31
                6.3.2.3. Inheritance of Parameters Defined at
                         Site Level and Site Network Access Level ..32
    6.4. Site Role .................................................32

Litkowski, et al. Standards Track [Page 2] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

    6.5. Site Belonging to Multiple VPNs ...........................33
         6.5.1. Site VPN Flavor ....................................33
                6.5.1.1. Single VPN Attachment:
                         site-vpn-flavor-single ....................33
                6.5.1.2. MultiVPN Attachment:
                         site-vpn-flavor-multi .....................33
                6.5.1.3. SubVPN Attachment: site-vpn-flavor-sub ....34
                6.5.1.4. NNI: site-vpn-flavor-nni ..................36
         6.5.2. Attaching a Site to a VPN ..........................37
                6.5.2.1. Referencing a VPN .........................37
                6.5.2.2. VPN Policy ................................38
    6.6. Deciding Where to Connect the Site ........................40
         6.6.1. Constraint: Device .................................41
         6.6.2. Constraint/Parameter: Site Location ................41
         6.6.3. Constraint/Parameter: Access Type ..................42
         6.6.4. Constraint: Access Diversity .......................43
         6.6.5. Infeasible Access Placement ........................49
         6.6.6. Examples of Access Placement .......................50
                6.6.6.1. Multihoming ...............................50
                6.6.6.2. Site Offload ..............................53
                6.6.6.3. Parallel Links ............................59
                6.6.6.4. SubVPN with Multihoming ...................60
         6.6.7. Route Distinguisher and VRF Allocation .............64
    6.7. Site Network Access Availability ..........................64
    6.8. Traffic Protection ........................................66
    6.9. Security ..................................................66
         6.9.1. Authentication .....................................67
         6.9.2. Encryption .........................................67
    6.10. Management ...............................................68
    6.11. Routing Protocols ........................................68
         6.11.1. Handling of Dual Stack ............................69
         6.11.2. LAN Directly Connected to SP Network ..............70
         6.11.3. LAN Directly Connected to SP Network with
                 Redundancy ........................................70
         6.11.4. Static Routing ....................................70
         6.11.5. RIP Routing .......................................71
         6.11.6. OSPF Routing ......................................71
         6.11.7. BGP Routing .......................................73
    6.12. Service ..................................................75
         6.12.1. Bandwidth .........................................75
         6.12.2. QoS ...............................................75
                6.12.2.1. QoS Classification .......................75
                6.12.2.2. QoS Profile ..............................78
         6.12.3. Multicast .........................................81
    6.13. Enhanced VPN Features ....................................82
         6.13.1. Carriers' Carriers ................................82
    6.14. External ID References ...................................83

Litkowski, et al. Standards Track [Page 3] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

    6.15. Defining NNIs ............................................83
         6.15.1. Defining an NNI with the Option A Flavor ..........85
         6.15.2. Defining an NNI with the Option B Flavor ..........88
         6.15.3. Defining an NNI with the Option C Flavor ..........91
 7. Service Model Usage Example ....................................92
 8. Interaction with Other YANG Modules ............................98
 9. YANG Module ...................................................102
 10. Security Considerations ......................................154
 11. IANA Considerations ..........................................155
 12. References ...................................................155
    12.1. Normative References ....................................155
    12.2. Informative References ..................................157
 Acknowledgements .................................................157
 Contributors .....................................................157
 Authors' Addresses ...............................................157

1. Introduction

 This document defines a Layer 3 VPN service data model written in
 YANG.  The 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.

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

Litkowski, et al. Standards Track [Page 4] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 The terminology for describing YANG data models is found in
 [RFC7950].
 This document presents some configuration examples using XML
 representation.

1.2. Requirements Language

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

1.3. Tree Diagrams

 A simplified graphical representation of the data model is presented
 in Section 6.
 The meanings of the symbols in these diagrams are as follows:
 o  Brackets "[" and "]" enclose list keys.
 o  Curly braces "{" and "}" contain names of optional features that
    make the corresponding node conditional.
 o  Abbreviations before data node names: "rw" means configuration
    data (read-write), and "ro" means state data (read-only).
 o  Symbols after data node names: "?" means an optional node, and "*"
    denotes a "list" or "leaf-list".
 o  Parentheses enclose choice and case nodes, and case nodes are also
    marked with a colon (":").
 o  Ellipsis ("...") stands for contents of subtrees that are not
    shown.

2. Acronyms

 AAA: Authentication, Authorization, and Accounting.
 ACL: Access Control List.
 ADSL: Asymmetric DSL.
 AH: Authentication Header.
 AS: Autonomous System.

Litkowski, et al. Standards Track [Page 5] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 ASBR: Autonomous System Border Router.
 ASM: Any-Source Multicast.
 BAS: Broadband Access Switch.
 BFD: Bidirectional Forwarding Detection.
 BGP: Border Gateway Protocol.
 BSR: Bootstrap Router.
 CE: Customer Edge.
 CLI: Command Line Interface.
 CsC: Carriers' Carriers.
 CSP: Cloud Service Provider.
 DHCP: Dynamic Host Configuration Protocol.
 DSLAM: Digital Subscriber Line Access Multiplexer.
 ESP: Encapsulating Security Payload.
 GRE: Generic Routing Encapsulation.
 IGMP: Internet Group Management Protocol.
 LAN: Local Area Network.
 MLD: Multicast Listener Discovery.
 MTU: Maximum Transmission Unit.
 NAT: Network Address Translation.
 NETCONF: Network Configuration Protocol.
 NNI: Network-to-Network Interface.
 OAM: Operations, Administration, and Maintenance.
 OSPF: Open Shortest Path First.
 OSS: Operations Support System.

Litkowski, et al. Standards Track [Page 6] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 PE: Provider Edge.
 PIM: Protocol Independent Multicast.
 POP: Point of Presence.
 QoS: Quality of Service.
 RD: Route Distinguisher.
 RIP: Routing Information Protocol.
 RP: Rendezvous Point.
 RT: Route Target.
 SFTP: Secure FTP.
 SLA: Service Level Agreement.
 SLAAC: Stateless Address Autoconfiguration.
 SP: Service Provider.
 SPT: Shortest Path Tree.
 SSM: Source-Specific Multicast.
 VM: Virtual Machine.
 VPN: Virtual Private Network.
 VRF: VPN Routing and Forwarding.
 VRRP: Virtual Router Redundancy Protocol.

3. Definitions

 Customer Edge (CE) Device: A CE is equipment dedicated to a
 particular customer; it is directly connected (at Layer 3) to one or
 more PE devices via attachment circuits.  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
 attachment circuits.

Litkowski, et al. Standards Track [Page 7] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 Provider Edge (PE) Device: A PE is equipment managed by the SP; it
 can support multiple VPNs for different customers and is directly
 connected (at Layer 3) to one or more CE devices via attachment
 circuits.  A PE is usually located at an SP point of presence (POP)
 and is managed by the SP.
 PE-Based VPNs: The PE devices know that certain traffic is VPN
 traffic.  They forward the traffic (through tunnels) based on the
 destination IP address of the packet and, optionally, based on other
 information in the IP header of the packet.  The PE devices are
 themselves the tunnel endpoints.  The tunnels may make use of various
 encapsulations to send traffic over the SP network (such as, but not
 restricted to, GRE, IP-in-IP, IPsec, or MPLS tunnels).

4. Layer 3 IP VPN Service Model

 A Layer 3 IP VPN service is a collection of sites that are authorized
 to exchange traffic between each other over a shared IP
 infrastructure.  This Layer 3 VPN service model aims at providing a
 common understanding of how the corresponding IP VPN service is to be
 deployed over the shared infrastructure.  This service model is
 limited to BGP PE-based VPNs as described in [RFC4026], [RFC4110],
 and [RFC4364].

Litkowski, et al. Standards Track [Page 8] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

5. Service Data Model Usage

              l3vpn-svc |
                Model   |
                        |
                 +------------------+         +-----+
                 |   Orchestration  | < --- > | OSS |
                 +------------------+         +-----+
                    |            |
            +----------------+   |
            | Config manager |   |
            +----------------+   |
                    |            |
                    | NETCONF/CLI ...
                    |            |
      +------------------------------------------------+
                           Network
                         +++++++
                         + AAA +
                         +++++++
 ++++++++   Bearer    ++++++++           ++++++++      ++++++++
 + CE A + ----------- + PE A +           + PE B + ---- + CE B +
 ++++++++  Connection ++++++++           ++++++++      ++++++++
            Site A                               Site B
 The idea of the L3 IP VPN service model is to propose an abstracted
 interface between customers and network operators to manage
 configuration of components of an L3VPN service.  A typical scenario
 would be to use this model as an input for an orchestration layer
 that will be responsible for translating it to an orchestrated
 configuration of network elements that will be part of the service.
 The network elements can be routers but can also be servers (like
 AAA); the network's configuration is not limited to these examples.
 The configuration of network elements can be done via the CLI,
 NETCONF/RESTCONF [RFC6241] [RFC8040] coupled with YANG data models of
 a specific configuration (BGP, VRF, BFD, etc.), or some other
 technique, as preferred by the operator.
 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.

Litkowski, et al. Standards Track [Page 9] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

6. Design of the Data Model

 The YANG module is divided into two main containers: "vpn-services"
 and "sites".
 The "vpn-service" list under the vpn-services container defines
 global parameters for the VPN service for a specific customer.
 A "site" is composed of at least one "site-network-access" and, in
 the case of multihoming, may have multiple site-network-access
 points.  The site-network-access attachment is done through a
 "bearer" with an "ip-connection" on top.  The bearer refers to
 properties of the attachment that are below Layer 3, while the
 connection refers to properties oriented to the Layer 3 protocol.
 The bearer may be allocated dynamically by the SP, and the customer
 may provide some constraints or parameters to drive the placement of
 the access.
 Authorization of traffic exchange is done through what we call a VPN
 policy or VPN service topology defining routing exchange rules
 between sites.
 The figure below describes the overall structure of the YANG module:
 module: ietf-l3vpn-svc
   +--rw l3vpn-svc
    +--rw vpn-services
    | +--rw vpn-service* [vpn-id]
    |   +--rw vpn-id         svc-id
    |   +--rw customer-name?     string
    |   +--rw vpn-service-topology?  identityref
    |   +--rw cloud-accesses {cloud-access}?
    |   | +--rw cloud-access* [cloud-identifier]
    |   |   +--rw cloud-identifier    string
    |   |   +--rw (list-flavor)?
    |   |   | +--:(permit-any)
    |   |   | | +--rw permit-any?      empty
    |   |   | +--:(deny-any-except)
    |   |   | | +--rw permit-site*      leafref
    |   |   | +--:(permit-any-except)
    |   |   |   +--rw deny-site*       leafref
    |   |   +--rw authorized-sites
    |   |   | +--rw authorized-site* [site-id]
    |   |   |   +--rw site-id  leafref
    |   |   +--rw denied-sites
    |   |   | +--rw denied-site* [site-id]
    |   |   |   +--rw site-id  leafref
    |   |   +--rw address-translation

Litkowski, et al. Standards Track [Page 10] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

    |   |    +--rw nat44
    |   |      +--rw enabled?         boolean
    |   |      +--rw nat44-customer-address?  inet:ipv4-address
    |   +--rw multicast {multicast}?
    |   | +--rw enabled?         boolean
    |   | +--rw customer-tree-flavors
    |   | | +--rw tree-flavor*  identityref
    |   | +--rw rp
    |   |   +--rw rp-group-mappings
    |   |   | +--rw rp-group-mapping* [id]
    |   |   |   +--rw id         uint16
    |   |   |   +--rw provider-managed
    |   |   |   | +--rw enabled?          boolean
    |   |   |   | +--rw rp-redundancy?       boolean
    |   |   |   | +--rw optimal-traffic-delivery?  boolean
    |   |   |   +--rw rp-address?     inet:ip-address
    |   |   |   +--rw groups
    |   |   |    +--rw group* [id]
    |   |   |      +--rw id        uint16
    |   |   |      +--rw (group-format)?
    |   |   |       +--:(startend)
    |   |   |       | +--rw group-start?   inet:ip-address
    |   |   |       | +--rw group-end?    inet:ip-address
    |   |   |       +--:(singleaddress)
    |   |   |         +--rw group-address?  inet:ip-address
    |   |   +--rw rp-discovery
    |   |    +--rw rp-discovery-type?  identityref
    |   |    +--rw bsr-candidates
    |   |      +--rw bsr-candidate-address*  inet:ip-address
    |   +--rw carrierscarrier?    boolean {carrierscarrier}?
    |   +--rw extranet-vpns {extranet-vpn}?
    |    +--rw extranet-vpn* [vpn-id]
    |      +--rw vpn-id       svc-id
    |      +--rw local-sites-role?  identityref
    +--rw sites
      +--rw site* [site-id]
       +--rw site-id         svc-id
       +--rw requested-site-start?  yang:date-and-time
       +--rw requested-site-stop?   yang:date-and-time
       +--rw locations
       | +--rw location* [location-id]
       |   +--rw location-id   svc-id
       |   +--rw address?    string
       |   +--rw postal-code?  string
       |   +--rw state?     string
       |   +--rw city?      string
       |   +--rw country-code?  string

Litkowski, et al. Standards Track [Page 11] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

       +--rw devices
       | +--rw device* [device-id]
       |   +--rw device-id   svc-id
       |   +--rw location?   leafref
       |   +--rw management
       |    +--rw address-family?  address-family
       |    +--rw address?     inet:ip-address
       +--rw site-diversity {site-diversity}?
       | +--rw groups
       |   +--rw group* [group-id]
       |    +--rw group-id  string
       +--rw management
       | +--rw type?  identityref
       +--rw vpn-policies
       | +--rw vpn-policy* [vpn-policy-id]
       |   +--rw vpn-policy-id  svc-id
       |   +--rw entries* [id]
       |    +--rw id    svc-id
       |    +--rw filter
       |    | +--rw (lan)?
       |    |   +--:(prefixes)
       |    |   | +--rw ipv4-lan-prefix*  inet:ipv4-prefix {ipv4}?
       |    |   | +--rw ipv6-lan-prefix*  inet:ipv6-prefix {ipv6}?
       |    |   +--:(lan-tag)
       |    |    +--rw lan-tag*      string
       |    +--rw vpn
       |      +--rw vpn-id    leafref
       |      +--rw site-role?  identityref
       +--rw site-vpn-flavor?     identityref
       +--rw maximum-routes
       | +--rw address-family* [af]
       |   +--rw af        address-family
       |   +--rw maximum-routes?  uint32
       +--rw security
       | +--rw authentication
       | +--rw encryption {encryption}?
       |   +--rw enabled?       boolean
       |   +--rw layer         enumeration
       |   +--rw encryption-profile
       |    +--rw (profile)?
       |      +--:(provider-profile)
       |      | +--rw profile-name?  string
       |      +--:(customer-profile)
       |       +--rw algorithm?    string
       |       +--rw (key-type)?
       |         +--:(psk)
       |         | +--rw preshared-key?  string
       |         +--:(pki)

Litkowski, et al. Standards Track [Page 12] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

       +--rw service
       | +--rw qos {qos}?
       | | +--rw qos-classification-policy
       | | | +--rw rule* [id]
       | | |   +--rw id          uint16
       | | |   +--rw (match-type)?
       | | |   | +--:(match-flow)
       | | |   | | +--rw match-flow
       | | |   | |   +--rw dscp?        inet:dscp
       | | |   | |   +--rw dot1p?        uint8
       | | |   | |   +--rw ipv4-src-prefix?   inet:ipv4-prefix
       | | |   | |   +--rw ipv6-src-prefix?   inet:ipv6-prefix
       | | |   | |   +--rw ipv4-dst-prefix?   inet:ipv4-prefix
       | | |   | |   +--rw ipv6-dst-prefix?   inet:ipv6-prefix
       | | |   | |   +--rw l4-src-port?     inet:port-number
       | | |   | |   +--rw target-sites*    svc-id
       | | |   | |   +--rw l4-src-port-range
       | | |   | |   | +--rw lower-port?  inet:port-number
       | | |   | |   | +--rw upper-port?  inet:port-number
       | | |   | |   +--rw l4-dst-port?     inet:port-number
       | | |   | |   +--rw l4-dst-port-range
       | | |   | |   | +--rw lower-port?  inet:port-number
       | | |   | |   | +--rw upper-port?  inet:port-number
       | | |   | |   +--rw protocol-field?   union
       | | |   | +--:(match-application)
       | | |   |   +--rw match-application?  identityref
       | | |   +--rw target-class-id?   string
       | | +--rw qos-profile
       | |   +--rw (qos-profile)?
       | |    +--:(standard)
       | |    | +--rw profile?  string
       | |    +--:(custom)
       | |      +--rw classes {qos-custom}?
       | |       +--rw class* [class-id]
       | |         +--rw class-id   string
       | |         +--rw rate-limit?  uint8
       | |         +--rw latency
       | |         | +--rw (flavor)?
       | |         |    ...
       | |         +--rw jitter
       | |         | +--rw (flavor)?
       | |         |    ...
       | |         +--rw bandwidth
       | |          +--rw guaranteed-bw-percent?  uint8
       | |          +--rw end-to-end?       empty
       | +--rw carrierscarrier {carrierscarrier}?
       | | +--rw signalling-type?  enumeration

Litkowski, et al. Standards Track [Page 13] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

       | +--rw multicast {multicast}?
       |   +--rw multicast-site-type?    enumeration
       |   +--rw multicast-address-family
       |   | +--rw ipv4?  boolean {ipv4}?
       |   | +--rw ipv6?  boolean {ipv6}?
       |   +--rw protocol-type?       enumeration
       +--rw traffic-protection {fast-reroute}?
       | +--rw enabled?  boolean
       +--rw routing-protocols
       | +--rw routing-protocol* [type]
       |   +--rw type   identityref
       |   +--rw ospf {rtg-ospf}?
       |   | +--rw address-family*  address-family
       |   | +--rw area-address?   yang:dotted-quad
       |   | +--rw metric?      uint16
       |   | +--rw sham-links {rtg-ospf-sham-link}?
       |   |   +--rw sham-link* [target-site]
       |   |    +--rw target-site  svc-id
       |   |    +--rw metric?    uint16
       |   +--rw bgp {rtg-bgp}?
       |   | +--rw autonomous-system?  uint32
       |   | +--rw address-family*   address-family
       |   +--rw static
       |   | +--rw cascaded-lan-prefixes
       |   |   +--rw ipv4-lan-prefixes* [lan next-hop] {ipv4}?
       |   |   | +--rw lan     inet:ipv4-prefix
       |   |   | +--rw lan-tag?  string
       |   |   | +--rw next-hop  inet:ipv4-address
       |   |   +--rw ipv6-lan-prefixes* [lan next-hop] {ipv6}?
       |   |    +--rw lan     inet:ipv6-prefix
       |   |    +--rw lan-tag?  string
       |   |    +--rw next-hop  inet:ipv6-address
       |   +--rw rip {rtg-rip}?
       |   | +--rw address-family*  address-family
       |   +--rw vrrp {rtg-vrrp}?
       |    +--rw address-family*  address-family
       +--ro actual-site-start?    yang:date-and-time
       +--ro actual-site-stop?    yang:date-and-time
       +--rw site-network-accesses
         +--rw site-network-access* [site-network-access-id]
          +--rw site-network-access-id   svc-id
          +--rw site-network-access-type?  identityref
          +--rw (location-flavor)
          | +--:(location)
          | | +--rw location-reference?     leafref
          | +--:(device)
          |   +--rw device-reference?      leafref

Litkowski, et al. Standards Track [Page 14] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

          +--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]
          |       |    ...
          |       +--:(all-accesses)
          |       | +--rw all-other-accesses?  empty
          |       +--:(all-groups)
          |         +--rw all-other-groups?   empty
          +--rw bearer
          | +--rw requested-type {requested-type}?
          | | +--rw requested-type?  string
          | | +--rw strict?      boolean
          | +--rw always-on?     boolean {always-on}?
          | +--rw bearer-reference?  string {bearer-reference}?
          +--rw ip-connection
          | +--rw ipv4 {ipv4}?
          | | +--rw address-allocation-type?   identityref
          | | +--rw number-of-dynamic-address?  uint8
          | | +--rw dhcp-relay
          | | | +--rw customer-dhcp-servers
          | | |   +--rw server-ip-address*  inet:ipv4-address
          | | +--rw addresses
          | |   +--rw provider-address?  inet:ipv4-address
          | |   +--rw customer-address?  inet:ipv4-address
          | |   +--rw mask?        uint8
          | +--rw ipv6 {ipv6}?
          | | +--rw address-allocation-type?   identityref
          | | +--rw number-of-dynamic-address?  uint8
          | | +--rw dhcp-relay
          | | | +--rw customer-dhcp-servers
          | | |   +--rw server-ip-address*  inet:ipv6-address
          | | +--rw addresses
          | |   +--rw provider-address?  inet:ipv6-address
          | |   +--rw customer-address?  inet:ipv6-address
          | |   +--rw mask?        uint8

Litkowski, et al. Standards Track [Page 15] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

          | +--rw oam
          |   +--rw bfd {bfd}?
          |    +--rw enabled?    boolean
          |    +--rw (holdtime)?
          |      +--:(profile)
          |      | +--rw profile-name?  string
          |      +--:(fixed)
          |       +--rw fixed-value?  uint32
          +--rw security
          | +--rw authentication
          | +--rw encryption {encryption}?
          |   +--rw enabled?       boolean
          |   +--rw layer         enumeration
          |   +--rw encryption-profile
          |    +--rw (profile)?
          |      +--:(provider-profile)
          |      | +--rw profile-name?  string
          |      +--:(customer-profile)
          |       +--rw algorithm?    string
          |       +--rw (key-type)?
          |         +--:(psk)
          |         |   ...
          |         +--:(pki)
          +--rw service
          | +--rw svc-input-bandwidth?  uint32
          | +--rw svc-output-bandwidth?  uint32
          | +--rw svc-mtu?        uint16
          | +--rw qos {qos}?
          | | +--rw qos-classification-policy
          | | | +--rw rule* [id]
          | | |   +--rw id          uint16
          | | |   +--rw (match-type)?
          | | |   | +--:(match-flow)
          | | |   | | +--rw match-flow
          | | |   | |    ...
          | | |   | +--:(match-application)
          | | |   |   +--rw match-application?  identityref
          | | |   +--rw target-class-id?   string
          | | +--rw qos-profile
          | |   +--rw (qos-profile)?
          | |    +--:(standard)
          | |    | +--rw profile?  string
          | |    +--:(custom)
          | |      +--rw classes {qos-custom}?
          | |       +--rw class* [class-id]
          | |          ...

Litkowski, et al. Standards Track [Page 16] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

          | +--rw carrierscarrier {carrierscarrier}?
          | | +--rw signalling-type?  enumeration
          | +--rw multicast {multicast}?
          |   +--rw multicast-site-type?    enumeration
          |   +--rw multicast-address-family
          |   | +--rw ipv4?  boolean {ipv4}?
          |   | +--rw ipv6?  boolean {ipv6}?
          |   +--rw protocol-type?       enumeration
          +--rw routing-protocols
          | +--rw routing-protocol* [type]
          |   +--rw type   identityref
          |   +--rw ospf {rtg-ospf}?
          |   | +--rw address-family*  address-family
          |   | +--rw area-address?   yang:dotted-quad
          |   | +--rw metric?      uint16
          |   | +--rw sham-links {rtg-ospf-sham-link}?
          |   |   +--rw sham-link* [target-site]
          |   |    +--rw target-site  svc-id
          |   |    +--rw metric?    uint16
          |   +--rw bgp {rtg-bgp}?
          |   | +--rw autonomous-system?  uint32
          |   | +--rw address-family*   address-family
          |   +--rw static
          |   | +--rw cascaded-lan-prefixes
          |   |   +--rw ipv4-lan-prefixes* [lan next-hop] {ipv4}?
          |   |   | +--rw lan     inet:ipv4-prefix
          |   |   | +--rw lan-tag?  string
          |   |   | +--rw next-hop  inet:ipv4-address
          |   |   +--rw ipv6-lan-prefixes* [lan next-hop] {ipv6}?
          |   |    +--rw lan     inet:ipv6-prefix
          |   |    +--rw lan-tag?  string
          |   |    +--rw next-hop  inet:ipv6-address
          |   +--rw rip {rtg-rip}?
          |   | +--rw address-family*  address-family
          |   +--rw vrrp {rtg-vrrp}?
          |    +--rw address-family*  address-family
          +--rw availability
          | +--rw access-priority?  uint32
          +--rw vpn-attachment
            +--rw (attachment-flavor)
             +--:(vpn-policy-id)
             | +--rw vpn-policy-id?  leafref
             +--:(vpn-id)
               +--rw vpn-id?     leafref
               +--rw site-role?    identityref

Litkowski, et al. Standards Track [Page 17] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

6.1. Features and Augmentation

 The model defined in this document implements many features that
 allow implementations to be modular.  As an example, an
 implementation may support only IPv4 VPNs (IPv4 feature), IPv6 VPNs
 (IPv6 feature), or both (by advertising both features).  The routing
 protocols proposed to the customer may also be enabled through
 features.  This model also proposes some features for options that
 are more advanced, such as support for extranet VPNs (Section 6.2.4),
 site diversity (Section 6.6), and QoS (Section 6.12.2).
 In addition, as for any YANG model, this service model can be
 augmented to implement new behaviors or specific features.  For
 example, this model proposes different options for IP address
 assignments; if those options do not fulfill all requirements, new
 options can be added through augmentation.

6.2. VPN Service Overview

 A vpn-service list item contains generic information about the VPN
 service.  The "vpn-id" provided in the vpn-service list refers to an
 internal reference for this VPN service, while the customer name
 refers to a more-explicit reference to the customer.  This identifier
 is purely internal to the organization responsible for the VPN
 service.

6.2.1. VPN Service Topology

 The type of VPN service topology is required for configuration.  Our
 proposed model 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 via augmentation.
 By default, the any-to-any VPN service topology is used.

Litkowski, et al. Standards Track [Page 18] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

6.2.1.1. Route Target Allocation

 A Layer 3 PE-based VPN is built using route targets (RTs) as
 described in [RFC4364].  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 below.
                                  Management system
                   <------------------------------------------------->
                                               Request RT
                    +-----------------------+  Topo a2a   +----------+
         RESTCONF   |                       |  ----->     |          |
 User ------------- | Service Orchestration |             | Network  |
         l3vpn-svc  |                       |  <-----     |   OSS    |
           Model    +-----------------------+   Response  +----------+
                                                RT1, RT2
 In the example above, a service orchestration, owning the
 instantiation of this service model, requests RTs to the network OSS.
 Based on the requested VPN service topology, the network OSS replies
 with one or multiple RTs.  The interface between this service
 orchestration and the network OSS is out of scope for this document.
                            +---------------------------+
                 RESTCONF   |                           |
         User ------------- |   Service Orchestration   |
                 l3vpn-svc  |                           |
                   Model    |                           |
                            |  RT pool: 10:1->10:10000  |
                            |  RT pool: 20:50->20:5000  |
                            +---------------------------+
 In the example above, a service orchestration, owning the
 instantiation of this service model, owns one or more pools of RTs
 (specified by the SP) that can be allocated.  Based on the requested
 VPN service topology, it will allocate one or multiple RTs from the
 pool.
 The mechanisms shown above are just examples and should not be
 considered an exhaustive list of solutions.

Litkowski, et al. Standards Track [Page 19] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

6.2.1.2. Any-to-Any

   +------------------------------------------------------------+
   |  VPN1_Site1 ------ PE1               PE2 ------ VPN1_Site2 |
   |                                                            |
   |  VPN1_Site3 ------ PE3               PE4 ------ VPN1_Site4 |
   +------------------------------------------------------------+
                   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 IP VPN service request through this model is
 expected to assign and then configure the VRF and RTs on the
 appropriate PEs.  In the any-to-any case, a single RT is generally
 required, and every VRF imports and exports this RT.

6.2.1.3. Hub and Spoke

   +-------------------------------------------------------------+
   |   Hub_Site1 ------ PE1               PE2 ------ Spoke_Site1 |
   |                          +----------------------------------+
   |                          |
   |                          +----------------------------------+
   |   Hub_Site2 ------ PE3               PE4 ------ Spoke_Site2 |
   +-------------------------------------------------------------+
                   Hub-and-Spoke VPN Service Topology
 In the Hub-and-Spoke VPN service topology, all Spoke sites can
 communicate only with Hub sites but not with each other, and Hubs can
 also communicate with each other.  The management system that owns an
 any-to-any IP VPN 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 case, two RTs are generally required (one RT for
 Hub routes and 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.  It will also import the Hub RT to allow
 Hub-to-Hub communication.  A Spoke VRF that connects Spoke sites will
 export Spoke routes with the Spoke RT and will import Hub routes
 through the Hub RT.

Litkowski, et al. Standards Track [Page 20] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 The management system MUST take into account constraints on Hub-and-
 Spoke connections.  For example, if a management system decides to
 mesh a Spoke site and a Hub site on the same PE, it needs to mesh
 connections in different VRFs, as shown in the figure below.
    Hub_Site ------- (VRF_Hub)  PE1
                               (VRF_Spoke)
                                 /  |
 Spoke_Site1 -------------------+   |
                                    |
 Spoke_Site2 -----------------------+

6.2.1.4. Hub and Spoke Disjoint

   +-------------------------------------------------------------+
   |   Hub_Site1 ------ PE1               PE2 ------ Spoke_Site1 |
   +--------------------------+  +-------------------------------+
                              |  |
   +--------------------------+  +-------------------------------+
   |   Hub_Site2 ------ PE3               PE4 ------ Spoke_Site2 |
   +-------------------------------------------------------------+
             Hub and Spoke Disjoint VPN Service Topology
 In the Hub and Spoke disjoint VPN service topology, all Spoke sites
 can communicate only with Hub sites but not with each other, and Hubs
 cannot communicate with each other.  The management system that owns
 an any-to-any IP VPN 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 case, two RTs are required (one RT for Hub
 routes and 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.
 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.

Litkowski, et al. Standards Track [Page 21] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

6.2.2. Cloud Access

 The proposed model provides cloud access configuration via the
 "cloud-accesses" container.  The usage of cloud-access is targeted
 for the public cloud.  An Internet access can also be considered a
 public cloud access service.  The cloud-accesses container provides
 parameters for network address translation and authorization rules.
 A private cloud access may be addressed through NNIs, as described in
 Section 6.15.
 A cloud identifier is used to reference the target service.  This
 identifier is local to each administration.
 The model allows for source address translation before accessing the
 cloud.  IPv4-to-IPv4 address translation (NAT44) is the only
 supported option, but other options can be added through
 augmentation.  If IP source address translation is required to access
 the cloud, the "enabled" leaf MUST be set to true in the "nat44"
 container.  An IP address may be provided in the "customer-address"
 leaf if the customer is providing the IP address to be used for the
 cloud access.  If the SP is providing this address,
 "customer-address" is not necessary, as it can be picked from a pool
 of SPs.
 By default, all sites in the IP VPN MUST be authorized to access the
 cloud.  If restrictions are required, a user MAY configure 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.

Litkowski, et al. Standards Track [Page 22] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

                   IP VPN
         ++++++++++++++++++++++++++++++++     ++++++++++++
         +             Site 3           + --- +  Cloud 1 +
         + Site 1                       +     ++++++++++++
         +                              +
         + Site 2                       + --- ++++++++++++
         +                              +     + Internet +
         +            Site 4            +     ++++++++++++
         ++++++++++++++++++++++++++++++++
                      |
                 +++++++++++
                 + Cloud 2 +
                 +++++++++++
 In the example above, we configure the global VPN to access the
 Internet by creating a cloud-access pointing to the cloud identifier
 for the Internet service.  No authorized sites will be configured, as
 all sites are required to access the Internet.  The
 "address-translation/nat44/enabled" leaf will be set to true.
 <vpn-service>
     <vpn-id>123456487</vpn-id>
     <cloud-accesses>
      <cloud-access>
         <cloud-identifier>INTERNET</cloud-identifier>
         <address-translation>
           <nat44>
             <enabled>true</enabled>
           </nat44>
         </address-translation>
      </cloud-access>
     </cloud-accesses>
 </vpn-service>

Litkowski, et al. Standards Track [Page 23] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 If Site 1 and Site 2 require access to Cloud 1, a new cloud-access
 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.
 <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>
 </vpn-service>
 If all sites except Site 1 require access to Cloud 2, a new
 cloud-access 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.
 <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>
 </vpn-service>

6.2.3. Multicast Service

 Multicast in IP VPNs is described in [RFC6513].
 If multicast support is required for an IP VPN, some global multicast
 parameters are required as input for the service request.
 Users of this model will need to provide the flavors of trees that
 will be used by customers within the IP VPN (customer tree).  The
 proposed model supports bidirectional, shared, and source-based trees
 (and can be augmented).  Multiple flavors of trees can be supported
 simultaneously.

Litkowski, et al. Standards Track [Page 24] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

                                 Operator network
                                 ______________
                                /               \
                               |                 |
                        (SSM tree)               |
  Recv (IGMPv3) -- Site2 ------- PE2             |
                               |             PE1 --- Site1 --- Source1
                               |                 |        \
                               |                 |         -- Source2
                               |                 |
                         (ASM tree)              |
  Recv (IGMPv2) -- Site3 ------- PE3             |
                               |                 |
                         (SSM tree)              |
  Recv (IGMPv3) -- Site4 ------- PE4             |
                               | /               |
  Recv (IGMPv2) -- Site5 --------                |
                         (ASM tree)              |
                               |                 |
                                \_______________/
 When an ASM flavor is requested, this model requires that the "rp"
 and "rp-discovery" parameters be filled.  Multiple RP-to-group
 mappings can be created using the "rp-group-mappings" container.  For
 each mapping, the SP can manage the RP service by setting the
 "provider-managed/enabled" leaf to true.  In the case of a provider-
 managed RP, the user can request RP redundancy and/or optimal traffic
 delivery.  Those parameters will help the SP select the appropriate
 technology or architecture to fulfill the customer service
 requirement: for instance, in the case of a request for optimal
 traffic delivery, an SP may use Anycast-RP or RP-tree-to-SPT
 switchover architectures.
 In the case of a customer-managed RP, the RP address must be filled
 in the RP-to-group mappings using the "rp-address" leaf.  This leaf
 is not needed for a provider-managed RP.
 Users can define a specific mechanism for RP discovery, such as the
 "auto-rp", "static-rp", or "bsr-rp" modes.  By default, the model
 uses "static-rp" if ASM is requested.  A single rp-discovery
 mechanism is allowed for the VPN.  The "rp-discovery" container can
 be used for both provider-managed and customer-managed RPs.  In the
 case of a provider-managed RP, if the user wants to use "bsr-rp" as a
 discovery protocol, an SP should consider the provider-managed
 "rp-group-mappings" for the "bsr-rp" configuration.  The SP will then
 configure its selected RPs to be "bsr-rp-candidates".  In the case of
 a customer-managed RP and a "bsr-rp" discovery mechanism, the
 "rp-address" provided will be the bsr-rp candidate.

Litkowski, et al. Standards Track [Page 25] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

6.2.4. 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)
 In the figure above, VPN B has some resources on Site B that need to
 be available to some customers/partners.  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 6.5.2.2.  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 must be used on
 customer VPNs accessing extranet resources in another VPN.  In the
 figure above, 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 6.4.  Based on this, the requirements described in
 Section 6.4 regarding the site-role leaf are also applicable here.

Litkowski, et al. Standards Track [Page 26] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 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.
 <vpn-service>
     <vpn-id>VPNB</vpn-id>
     <vpn-service-topology>hub-spoke</vpn-service-topology>
 </vpn-service>
 <vpn-service>
     <vpn-id>VPNA</vpn-id>
     <vpn-service-topology>any-to-any</vpn-service-topology>
     <extranet-vpns>
         <extranet-vpn>
             <vpn-id>VPNB</vpn-id>
             <site-role>spoke-role</site-role>
         </extranet-vpn>
     </extranet-vpns>
 </vpn-service>
 This model does not define how the extranet configuration will be
 achieved.
 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 6.5.2, and especially a VPN policy as defined in
 Section 6.5.2.2.

6.3. Site Overview

 A site represents a connection of a customer office to one or more
 VPN services.
                                                  +-------------+
                                                 /               \
   +------------------+                   +-----|      VPN1       |
   |                  |                   |      \               /
   |  New York Office |------ (site) -----+       +-------------+
   |                  |                   |       +-------------+
   +------------------+                   |      /               \
                                          +-----|      VPN2       |
                                                 \               /
                                                  +-------------+

Litkowski, et al. Standards Track [Page 27] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 A site has several characteristics:
 o  Unique identifier (site-id): uniquely identifies the site within
    the overall network infrastructure.  The identifier is a string
    that allows any encoding for the local administration of the VPN
    service.
 o  Locations (locations): site location information that allows easy
    retrieval of information from the nearest available resources.  A
    site may be composed of multiple locations.
 o  Devices (devices): allows the customer to request one or more
    customer premises equipment entities from the SP for a particular
    site.
 o  Management (management): defines the type of management for the
    site -- for example, co-managed, customer-managed, or provider-
    managed.  See Section 6.10.
 o  Site network accesses (site-network-accesses): defines the list of
    network accesses associated with the sites, and their properties
    -- especially bearer, connection, and service parameters.
 A site-network-access represents an IP logical connection of a site.
 A site may have multiple site-network-accesses.
   +------------------+             Site
   |                  |-----------------------------------
   |                  |****** (site-network-access#1) ******
   |  New York Office |
   |                  |****** (site-network-access#2) ******
   |                  |-----------------------------------
   +------------------+
 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 overall parameters between the PE
 configuration and the CE configuration.

Litkowski, et al. Standards Track [Page 28] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

6.3.1. Devices and Locations

 A site may be composed of multiple locations.  All the locations will
 need to be configured as part of the "locations" container and list.
 A typical example of a multi-location site is a headquarters office
 in a city composed of multiple buildings.  Those buildings may be
 located in different parts of the city and may be linked by
 intra-city fibers (customer metropolitan area network).  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) ******
   | +--------------+ |
   |                  |-----------------------------------
   +------------------+
 A customer may also request 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
 ordered to 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
 the figure above, 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 he wants to implement: single CE, dual CE, etc.

Litkowski, et al. Standards Track [Page 29] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

6.3.2. Site Network Accesses

 As mentioned earlier, a site may be multihomed.  Each IP 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 3).
 o  connection: defines Layer 3 protocol parameters of the attachment.
 o  availability: defines the site's availability policy.  The
    availability parameters are defined in Section 6.7.
 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.
 The type of site-network-access may have an impact on the parameters
 offered to the customer, e.g., an SP may not offer encryption for
 multipoint accesses.  It is up to the provider to decide what
 parameter is supported for point-to-point and/or multipoint accesses;
 this topic is out of scope for this document.  Some containers
 proposed in the model may require extensions in order to work
 properly for multipoint accesses.

6.3.2.1. Bearer

 The bearer container defines the requirements for the site attachment
 to the provider network that are below Layer 3.
 The bearer parameters will help determine the access media to be
 used.  This is further described in Section 6.6.3.

Litkowski, et al. Standards Track [Page 30] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

6.3.2.2. Connection

 The "ip-connection" container defines the protocol parameters of the
 attachment (IPv4 and IPv6).  Depending on the management mode, it
 refers to PE-CE addressing or CE-to-customer-LAN 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 connection.  For a provider-managed site, it refers to the
 CE-to-LAN connection.

6.3.2.2.1. IP Addressing

 An IP subnet can be configured for either IPv4 or IPv6 Layer 3
 protocols.  For a dual-stack connection, two subnets will be
 provided, one for each address family.
 The "address-allocation-type" determines how the address allocation
 needs to be done.  The current model proposes five ways to perform IP
 address allocation:
 o  provider-dhcp: The provider will provide DHCP service for customer
    equipment; this is applicable to either the "IPv4" container or
    the "IPv6" container.
 o  provider-dhcp-relay: The provider will provide DHCP relay service
    for customer equipment; this is applicable to both IPv4 and IPv6
    addressing.  The customer needs to populate the DHCP server list
    to be used.
 o  static-address: Addresses will be assigned manually; this is
    applicable to both IPv4 and IPv6 addressing.
 o  slaac: This parameter enables stateless address autoconfiguration
    [RFC4862].  This is applicable to IPv6 only.
 o  provider-dhcp-slaac: The provider will provide DHCP service for
    customer equipment, as well as stateless address
    autoconfiguration.  This is applicable to IPv6 only.
 In the dynamic addressing mechanism, the SP is expected to provide at
 least the IP address, mask, and default gateway information.

6.3.2.2.2. OAM

 A customer may require a specific IP connectivity fault detection
 mechanism on the IP connection.  The model supports BFD as a fault
 detection mechanism.  This can be extended with other mechanisms via
 augmentation.  The provider can propose some profiles to the

Litkowski, et al. Standards Track [Page 31] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 customer, depending on the service level the customer wants to
 achieve.  Profile names must be communicated to the customer.  This
 communication is out of scope for this document.  Some fixed values
 for the holdtime period may also be imposed by the customer if the
 provider allows the customer this function.
 The "oam" container can easily be augmented by other mechanisms; in
 particular, work done by the LIME Working Group
 (https://datatracker.ietf.org/wg/lime/charter/) may be reused in
 applicable scenarios.

6.3.2.3. Inheritance of Parameters Defined at Site Level and Site

        Network Access Level
 Some parameters can be configured at both the site level and the
 site-network-access level, e.g., routing, services, security.
 Inheritance applies when parameters are defined at the site level.
 If a parameter is configured at both the site level and the access
 level, the access-level parameter MUST override the site-level
 parameter.  Those parameters will be described later in this
 document.
 In terms of provisioning impact, it will be up to the implementation
 to decide on the appropriate behavior when modifying existing
 configurations.  But the SP will need to communicate to the user
 about the impact of using inheritance.  For example, if we consider
 that a site has already provisioned three site-network-accesses, what
 will happen if a customer changes a service parameter at the site
 level?  An implementation of this model may update the service
 parameters of all already-provisioned site-network-accesses (with
 potential impact on live traffic), or it may take into account this
 new parameter only for the new sites.

6.4. Site Role

 A VPN has a particular service topology, as described in
 Section 6.2.1.  As a consequence, each site belonging to a VPN is
 assigned with 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.

Litkowski, et al. Standards Track [Page 32] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

6.5. Site Belonging to Multiple VPNs

6.5.1. Site VPN Flavor

 A site may be part of one or multiple VPNs.  The "site-vpn-flavor"
 defines the way the VPN multiplexing is done.  The current version of
 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.
 o  site-vpn-flavor-sub: The site belongs to multiple VPNs with
    multiple logical accesses.  Each logical access may map to
    different VPNs (one or many).
 o  site-vpn-flavor-nni: The site represents an option A NNI.

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

 The figure below describes a single VPN attachment.  The site
 connects to only one VPN.
                                                    +--------+
 +------------------+             Site             /          \
 |                  |-----------------------------|            |
 |                  |***(site-network-access#1)***|    VPN1    |
 |  New York Office |                             |            |
 |                  |***(site-network-access#2)***|            |
 |                  |-----------------------------|            |
 +------------------+                              \          /
                                                    +--------+

6.5.1.2. MultiVPN Attachment: site-vpn-flavor-multi

 The figure below describes a site connected to multiple VPNs.
                                                         +---------+
                                                    +---/----+      \
 +------------------+             Site             /   |      \      |
 |                  |--------------------------------- |       |VPN B|
 |                  |***(site-network-access#1)******* |       |     |
 |  New York Office |                             |    |       |     |
 |                  |***(site-network-access#2)*******  \      |    /
 |                  |-----------------------------| VPN A+-----|---+
 +------------------+                              \          /
                                                    +--------+

Litkowski, et al. Standards Track [Page 33] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 In the example above, the New York office is multihomed.  Both
 logical accesses are using the same VPN attachment rules, and both
 are connected to VPN A and VPN B.
 Reaching VPN A or VPN B from the New York office will be done via
 destination-based routing.  Having the same destination reachable
 from the two VPNs may cause routing troubles.  The customer
 administration's role in this case would be to ensure the appropriate
 mapping of its prefixes in each VPN.

6.5.1.3. SubVPN Attachment: site-vpn-flavor-sub

 The figure below describes a subVPN attachment.  The site connects to
 multiple VPNs, but each logical access is attached to a particular
 set of VPNs.  A typical use case for a subVPN is a customer site used
 by multiple affiliates with private resources for each affiliate that
 cannot be shared (communication between the affiliates is prevented).
 It is similar to having separate sites, but in this case the customer
 wants to share some physical components while maintaining strong
 communication isolation between the affiliates.  In this example,
 site-network-access#1 is attached to VPN B, while
 site-network-access#2 is attached to VPN A.
 +------------------+         Site                      +--------+
 |                  |----------------------------------/          \
 |                  |****(site-network-access#1)******|    VPN B   |
 |  New York Office |                                  \          /
 |                  |                                   +--------+
 |                  |                                   +--------+
 |                  |                                  /          \
 |                  |****(site-network-access#2)******|    VPN A   |
 |                  |                                  \          /
 |                  |                                   +--------+
 |                  |-----------------------------------
 +------------------+

Litkowski, et al. Standards Track [Page 34] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 A multiVPN can be implemented in addition to a subVPN; as a
 consequence, each site-network-access can access multiple VPNs.  In
 the example below, site-network-access#1 is mapped to VPN B and
 VPN C, while site-network-access#2 is mapped to VPN A and VPN D.
 +-----------------+         Site                    +------+
 |                 |--------------------------------/       +-----+
 |                 |****(site-network-access#1)****| VPN B /       \
 | New York Office |                                \     |  VPN C  |
 |                 |                                 +-----\       /
 |                 |                                        +-----+
 |                 |
 |                 |                                 +-------+
 |                 |                                /        +-----+
 |                 |****(site-network-access#2)****| VPN A  /       \
 |                 |                                \      | VPN D   |
 |                 |                                 +------\       /
 |                 |---------------------------------        +-----+
 +-----------------+
 Multihoming is also possible with subVPNs; in this case,
 site-network-accesses are grouped, and a particular group will have
 access to the same set of VPNs.  In the example below,
 site-network-access#1 and site-network-access#2 are part of the same
 group (multihomed together) and are mapped to VPN B and VPN C; in
 addition, site-network-access#3 and site-network-access#4 are part of
 the same group (multihomed together) and are mapped to VPN A and
 VPN D.
 +-----------------+         Site                     +------+
 |                 |---------------------------------/       +-----+
 |                 |****(site-network-access#1)*****| VPN B /       \
 | New York Office |****(site-network-access#2)***** \     |  VPN C  |
 |                 |                                  +-----\       /
 |                 |                                         +-----+
 |                 |
 |                 |                                  +------+
 |                 |                                 /       +-----+
 |                 |****(site-network-access#3)*****| VPN A /       \
 |                 |****(site-network-access#4)***** \     | VPN D   |
 |                 |                                  +-----\       /
 |                 |----------------------------------       +-----+
 +-----------------+
 In terms of service configuration, a subVPN can be achieved by
 requesting that the site-network-access use the same bearer (see
 Sections 6.6.4 and 6.6.6.4 for more details).

Litkowski, et al. Standards Track [Page 35] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

6.5.1.4. NNI: site-vpn-flavor-nni

 A Network-to-Network Interface (NNI) scenario may be modeled using
 the sites container (see Section 6.15.1).  Using the sites container
 to model an NNI is only one possible option for NNIs (see
 Section 6.15).  This option is called "option A" by reference to the
 option A NNI defined in [RFC4364].  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., ACLs, routing policies).
        SP A                                             SP B
   -------------------                         -------------------
  /                   \                       /                   \
 |                     |                     |                     |
 |                 ++++++++ Inter-AS link ++++++++                 |
 |                 +      +_______________+      +                 |
 |                 +  (VRF1)---(VPN1)----(VRF1)  +                 |
 |                 + ASBR +               + ASBR +                 |
 |                 +  (VRF2)---(VPN2)----(VRF2)  +                 |
 |                 +      +_______________+      +                 |
 |                 ++++++++               ++++++++                 |
 |                     |                     |                     |
 |                     |                     |                     |
 |                     |                     |                     |
 |                 ++++++++ Inter-AS link ++++++++                 |
 |                 +      +_______________+      +                 |
 |                 +  (VRF1)---(VPN1)----(VRF1)  +                 |
 |                 + ASBR +               + ASBR +                 |
 |                 +  (VRF2)---(VPN2)----(VRF2)  +                 |
 |                 +      +_______________+      +                 |
 |                 ++++++++               ++++++++                 |
 |                     |                     |                     |
 |                     |                     |                     |
  \                   /                       \                   /
   -------------------                         -------------------
 The figure above describes 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 will be used
 to inform SP B that this is an NNI and not a regular customer site.
 The site-vpn-flavor-nni may be multihomed and multiVPN as well.

Litkowski, et al. Standards Track [Page 36] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

6.5.2. Attaching a Site to a VPN

 Due to the multiple site-vpn flavors, the attachment of a site to an
 IP VPN 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.
 A choice is implemented to allow the user to choose the flavor that
 provides the best fit.

6.5.2.1. 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 or subVPN with a single VPN attachment per
 logical access.  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.
 <site>
  <site-id>SITE1</site-id>
  <site-network-accesses>
   <site-network-access>
    <site-network-access-id>LA1</site-network-access-id>
    <vpn-attachment>
     <vpn-id>VPNA</vpn-id>
     <site-role>spoke-role</site-role>
    </vpn-attachment>
   </site-network-access>
   <site-network-access>
    <site-network-access-id>LA2</site-network-access-id>
    <vpn-attachment>
     <vpn-id>VPNB</vpn-id>
     <site-role>spoke-role</site-role>
    </vpn-attachment>
   </site-network-access>
  </site-network-accesses>
 </site>
 The example above describes a subVPN case where a site (SITE1) has
 two logical accesses (LA1 and LA2), with LA1 attached to VPNA and LA2
 attached to VPNB.

Litkowski, et al. Standards Track [Page 37] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

6.5.2.2. VPN Policy

 The "vpn-policy" list helps express a multiVPN scenario where a
 logical access belongs to multiple VPNs.  Multiple VPN policies can
 be created to handle the subVPN case where each logical access is
 part of a different set of 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 of the site should be part of a particular 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.
 +--------------------------------------------------------------+
 |       Site1 ------ PE7                                       |
 +-------------------------+                 [VPN2]             |
                           |                                    |
 +-------------------------+                                    |
 |       Site2 ------ PE3               PE4 ------ Site3        |
 +----------------------------------+                           |
                                    |                           |
 +------------------------------------------------------------+ |
 |       Site4 ------ PE5           |   PE6 ------ Site5      | |
 |                                                            | |
 |                      [VPN3]                                | |
 +------------------------------------------------------------+ |
                                    |                           |
                                    +---------------------------+
 In the example above, Site5 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 multiVPN scenario as follows:
 <site>
  <site-id>Site5</site-id>
  <vpn-policies>
   <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>

Litkowski, et al. Standards Track [Page 38] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

    <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>
    <site-network-access-id>LA1</site-network-access-id>
    <vpn-attachment>
     <vpn-policy-id>POLICY1</vpn-policy-id>
    </vpn-attachment>
   </site-network-access>
  </site-network-accesses>
 </site>
 Now, if a more-granular VPN attachment is necessary, filtering can be
 used.  For example, if LAN1 from Site5 must be attached to VPN2 as a
 Hub and LAN2 must be attached to VPN3, the following configuration
 can be used:
 <site>
  <site-id>Site5</site-id>
  <vpn-policies>
   <vpn-policy>
    <vpn-policy-id>POLICY1</vpn-policy-id>
    <entries>
     <id>ENTRY1</id>
     <filter>
      <lan-tag>LAN1</lan-tag>
     </filter>
     <vpn>
      <vpn-id>VPN2</vpn-id>
      <site-role>hub-role</site-role>
     </vpn>
    </entries>
    <entries>
     <id>ENTRY2</id>
     <filter>
      <lan-tag>LAN2</lan-tag>
     </filter>

Litkowski, et al. Standards Track [Page 39] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

     <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>
    <site-network-access-id>LA1</site-network-access-id>
    <vpn-attachment>
     <vpn-policy-id>POLICY1</vpn-policy-id>
    </vpn-attachment>
   </site-network-access>
  </site-network-accesses>
 </site>

6.6. 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, aggregation switch).
 The current model proposes parameters and constraints that can
 influence the meshing of the site-network-access.
 The management system SHOULD honor any customer constraints.  If a
 constraint is too strict and cannot be fulfilled, the management
 system MUST NOT provision the site and SHOULD provide relevant
 information to the user.  How the 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 are just hints for the management system for service
 placement.
 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: least load, distance, etc.

Litkowski, et al. Standards Track [Page 40] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

6.6.1. Constraint: Device

 In the case of provider management or co-management, one or more
 devices have been ordered by the customer.  The customer may force a
 particular site-network-access to be connected on a particular device
 that he ordered.
     New York Site
   +------------------+             Site
   | +--------------+ |-----------------------------------
   | | Manhattan    | |
   | |           CE1********* (site-network-access#1) ******
   | +--------------+ |
   | +--------------+ |
   | | Brooklyn  CE2********* (site-network-access#2) ******
   | +--------------+ |
   |                  |-----------------------------------
   +------------------+
 In the figure above, site-network-access#1 is associated with CE1 in
 the service request.  The SP must ensure the provisioning of this
 connection.

6.6.2. 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 ALPHA-2 code.
 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.

Litkowski, et al. Standards Track [Page 41] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

                                       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   |
                                    +---------+
 In the example above, 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 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.

6.6.3. 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.

Litkowski, et al. Standards Track [Page 42] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

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

6.6.4. 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" or
 "subVPN") 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

Litkowski, et al. Standards Track [Page 43] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 site level; as a consequence, all site-network-accesses under the
 site MUST inherit the group-ids of the site they belong to.  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 MUST never be taken into account in the targeted
 set -- 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 that the current
 site-network-access does not belong to.
 The current model proposes 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.
 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.
 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 DSLAM, 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.

Litkowski, et al. Standards Track [Page 44] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 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.  As
 an example, if we want a set of sites (Site#1 to Site#5) to be
 connected on different PEs, we can tag them with the same group-id
 and express a pe-diverse constraint for this group-id.
 <site>
  <site-id>SITE1</site-id>
  <site-network-accesses>
   <site-network-access>
    <site-network-access-id>1</site-network-access-id>
    <access-diversity>
     <groups>
      <group>
       <group-id>10</group-id>
      </group>
     </groups>
     <constraints>
      <constraint>
       <constraint-type>pe-diverse</constraint-type>
       <target>
        <group>
         <group-id>10</group-id>
        </group>
       </target>
      </constraint>
     </constraints>
    </access-diversity>
    <vpn-attachment>
     <vpn-id>VPNA</vpn-id>
     <site-role>spoke-role</site-role>
    </vpn-attachment>
   </site-network-access>
  </site-network-accesses>
 </site>

Litkowski, et al. Standards Track [Page 45] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 <site>
  <site-id>SITE2</site-id>
  <site-network-accesses>
   <site-network-access>
    <site-network-access-id>1</site-network-access-id>
    <access-diversity>
     <groups>
      <group>
       <group-id>10</group-id>
      </group>
     </groups>
     <constraints>
      <constraint>
       <constraint-type>pe-diverse</constraint-type>
       <target>
        <group>
         <group-id>10</group-id>
        </group>
       </target>
      </constraint>
     </constraints>
    </access-diversity>
    <vpn-attachment>
     <vpn-id>VPNA</vpn-id>
     <site-role>spoke-role</site-role>
    </vpn-attachment>
   </site-network-access>
  </site-network-accesses>
 </site>
 ...
 <site>
  <site-id>SITE5</site-id>
  <site-network-accesses>
   <site-network-access>
    <site-network-access-id>1</site-network-access-id>
    <access-diversity>
     <groups>
      <group>
       <group-id>10</group-id>
      </group>
     </groups>
     <constraints>
      <constraint>
       <constraint-type>pe-diverse</constraint-type>
       <target>
        <group>
         <group-id>10</group-id>
        </group>

Litkowski, et al. Standards Track [Page 46] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

       </target>
      </constraint>
     </constraints>
    </access-diversity>
    <vpn-attachment>
     <vpn-id>VPNA</vpn-id>
     <site-role>spoke-role</site-role>
    </vpn-attachment>
   </site-network-access>
  </site-network-accesses>
 </site>
 The group-id used to target some site-network-accesses may also be
 different than the one used by the current site-network-access.  This
 can be used to express that a group of sites has some constraints
 against another group of sites, but there is no constraint within the
 group.  For example, we consider a set of six sites and two groups;
 we want to ensure that a site in the first group must be pop-diverse
 from a site in the second group:
 <site>
  <site-id>SITE1</site-id>
  <site-network-accesses>
   <site-network-access>
    <site-network-access-id>1</site-network-access-id>
    <access-diversity>
     <groups>
      <group>
       <group-id>10</group-id>
      </group>
     </groups>
     <constraints>
      <constraint>
       <constraint-type>pop-diverse</constraint-type>
       <target>
        <group>
         <group-id>20</group-id>
        </group>
       </target>
      </constraint>
     </constraints>
    </access-diversity>
    <vpn-attachment>
     <vpn-id>VPNA</vpn-id>
     <site-role>spoke-role</site-role>
    </vpn-attachment>
   </site-network-access>
  </site-network-accesses>

Litkowski, et al. Standards Track [Page 47] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 </site>
 <site>
  <site-id>SITE2</site-id>
  <site-network-accesses>
   <site-network-access>
    <site-network-access-id>1</site-network-access-id>
    <access-diversity>
     <groups>
      <group>
       <group-id>10</group-id>
      </group>
     </groups>
     <constraints>
      <constraint>
       <constraint-type>pop-diverse</constraint-type>
       <target>
        <group>
         <group-id>20</group-id>
        </group>
       </target>
      </constraint>
     </constraints>
    </access-diversity>
    <vpn-attachment>
     <vpn-id>VPNA</vpn-id>
     <site-role>spoke-role</site-role>
    </vpn-attachment>
   </site-network-access>
  </site-network-accesses>
 </site>
 ...
 <site>
  <site-id>SITE5</site-id>
  <site-network-accesses>
   <site-network-access>
    <site-network-access-id>1</site-network-access-id>
    <access-diversity>
     <groups>
      <group>
       <group-id>20</group-id>
      </group>
     </groups>
     <constraints>
      <constraint>
       <constraint-type>pop-diverse</constraint-type>
       <target>
        <group>
         <group-id>10</group-id>

Litkowski, et al. Standards Track [Page 48] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

        </group>
       </target>
      </constraint>
     </constraints>
    </access-diversity>
    <vpn-attachment>
     <vpn-id>VPNA</vpn-id>
     <site-role>spoke-role</site-role>
    </vpn-attachment>
   </site-network-access>
  </site-network-accesses>
 </site>
 <site>
  <site-id>SITE6</site-id>
  <site-network-accesses>
   <site-network-access>
    <site-network-access-id>1</site-network-access-id>
    <access-diversity>
     <groups>
      <group>
       <group-id>20</group-id>
      </group>
     </groups>
     <constraints>
      <constraint>
       <constraint-type>pop-diverse</constraint-type>
       <target>
        <group>
         <group-id>10</group-id>
        </group>
       </target>
      </constraint>
     </constraints>
    </access-diversity>
    <vpn-attachment>
     <vpn-id>VPNA</vpn-id>
     <site-role>spoke-role</site-role>
    </vpn-attachment>
   </site-network-access>
  </site-network-accesses>
 </site>

6.6.5. Infeasible Access Placement

 Some infeasible access placement scenarios could be created via the
 proposed configuration framework.  Such infeasible access placement
 scenarios could result from constraints that are too restrictive,
 leading to infeasible access placement in the network or conflicting

Litkowski, et al. Standards Track [Page 49] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 constraints that would also lead to infeasible access placement.  An
 example of conflicting rules would be to request that
 site-network-access#1 be pe-diverse from site-network-access#2 and to
 request at the same time that site-network-access#2 be on the same PE
 as site-network-access#1.  When the management system cannot
 determine the placement of a site-network-access, it SHOULD return an
 error message indicating that placement was not possible.

6.6.6. Examples of Access Placement

6.6.6.1. Multihoming

 The customer wants to create a multihomed site.  The site will be
 composed of two site-network-accesses; for resiliency purposes, the
 customer wants the two site-network-accesses to be meshed on
 different POPs.
                                         POP#1
     +-------+                            +---------+
     |       |                            |   PE1   |
     |       |---site-network-access#1----|   PE2   |
     |       |                            |   PE3   |
     |       |                            +---------+
     | Site#1|
     |       |                               POP#2
     |       |                            +---------+
     |       |                            |   PE4   |
     |       |---site-network-access#2----|   PE5   |
     |       |                            |   PE6   |
     |       |                            +---------+
     +-------+
 This scenario can be expressed as follows:
 <site>
  <site-id>SITE1</site-id>
  <site-network-accesses>
   <site-network-access>
    <site-network-access-id>1</site-network-access-id>
    <access-diversity>
     <groups>
      <group>
       <group-id>10</group-id>
      </group>
     </groups>
     <constraints>
      <constraint>
       <constraint-type>pop-diverse</constraint-type>

Litkowski, et al. Standards Track [Page 50] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

       <target>
        <group>
         <group-id>20</group-id>
        </group>
       </target>
      </constraint>
     </constraints>
    </access-diversity>
    <vpn-attachment>
     <vpn-id>VPNA</vpn-id>
     <site-role>spoke-role</site-role>
    </vpn-attachment>
   </site-network-access>
   <site-network-access>
    <site-network-access-id>2</site-network-access-id>
    <access-diversity>
     <groups>
      <group>
       <group-id>20</group-id>
      </group>
     </groups>
     <constraints>
      <constraint>
       <constraint-type>pop-diverse</constraint-type>
       <target>
        <group>
         <group-id>10</group-id>
        </group>
       </target>
      </constraint>
     </constraints>
    </access-diversity>
    <vpn-attachment>
     <vpn-id>VPNA</vpn-id>
     <site-role>spoke-role</site-role>
    </vpn-attachment>
   </site-network-access>
  </site-network-accesses>
 </site>

Litkowski, et al. Standards Track [Page 51] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 But it can also be expressed as follows:
 <site>
  <site-id>SITE1</site-id>
  <site-network-accesses>
   <site-network-access>
    <site-network-access-id>1</site-network-access-id>
    <access-diversity>
     <constraints>
      <constraint>
       <constraint-type>pop-diverse</constraint-type>
       <target>
        <all-other-accesses/>
       </target>
      </constraint>
     </constraints>
    </access-diversity>
    <vpn-attachment>
     <vpn-id>VPNA</vpn-id>
     <site-role>spoke-role</site-role>
    </vpn-attachment>
   </site-network-access>
   <site-network-access>
    <site-network-access-id>2</site-network-access-id>
    <access-diversity>
     <constraints>
      <constraint>
       <constraint-type>pop-diverse</constraint-type>
       <target>
        <all-other-accesses/>
       </target>
      </constraint>
     </constraints>
    </access-diversity>
    <vpn-attachment>
     <vpn-id>VPNA</vpn-id>
     <site-role>spoke-role</site-role>
    </vpn-attachment>
   </site-network-access>
  </site-network-accesses>
 </site>

Litkowski, et al. Standards Track [Page 52] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

6.6.6.2. Site Offload

 The customer has six branch offices in a particular region, and he
 wants to prevent having all branch offices connected on the same PE.
 He wants to express that three branch offices cannot be connected on
 the same linecard.  Also, the other branch offices must be connected
 on a different POP.  Those other branch offices cannot also be
 connected on the same linecard.
                                      POP#1
                                   +---------+
                                   |   PE1   |
             Office#1 ---...       |   PE2   |
             Office#2 ---...       |   PE3   |
             Office#3 ---...       |   PE4   |
                                   +---------+
                                      POP#2
                                   +---------+
             Office#4 ---...       |   PE5   |
             Office#5 ---...       |   PE6   |
             Office#6 ---...       |   PE7   |
                                   +---------+
 This scenario can be expressed as follows:
 o  We need to create two groups of sites: Group#10, which is composed
    of Office#1, Office#2, and Office#3; and Group#20, which is
    composed of Office#4, Office#5, and Office#6.
 o  Sites within Group#10 must be pop-diverse from sites within
    Group#20, and vice versa.
 o  Sites within Group#10 must be linecard-diverse from other sites in
    Group#10 (same for Group#20).

Litkowski, et al. Standards Track [Page 53] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 <site>
  <site-id>Office1</site-id>
  <site-network-accesses>
   <site-network-access>
    <site-network-access-id>1</site-network-access-id>
    <access-diversity>
     <groups>
      <group>
       <group-id>10</group-id>
      </group>
     </groups>
     <constraints>
      <constraint>
       <constraint-type>pop-diverse</constraint-type>
       <target>
        <group>
         <group-id>20</group-id>
        </group>
       </target>
      </constraint>
      <constraint>
       <constraint-type>linecard-diverse</constraint-type>
       <target>
        <group>
         <group-id>10</group-id>
        </group>
       </target>
      </constraint>
     </constraints>
    </access-diversity>
    <vpn-attachment>
     <vpn-id>VPNA</vpn-id>
     <site-role>spoke-role</site-role>
    </vpn-attachment>
   </site-network-access>
  </site-network-accesses>
 </site>
 <site>
  <site-id>Office2</site-id>
  <site-network-accesses>
   <site-network-access>
    <site-network-access-id>1</site-network-access-id>
    <access-diversity>
     <groups>
      <group>
       <group-id>10</group-id>
      </group>
     </groups>

Litkowski, et al. Standards Track [Page 54] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

     <constraints>
      <constraint>
       <constraint-type>pop-diverse</constraint-type>
       <target>
        <group>
         <group-id>20</group-id>
        </group>
       </target>
      </constraint>
      <constraint>
       <constraint-type>linecard-diverse</constraint-type>
       <target>
        <group>
         <group-id>10</group-id>
        </group>
       </target>
      </constraint>
     </constraints>
    </access-diversity>
    <vpn-attachment>
     <vpn-id>VPNA</vpn-id>
     <site-role>spoke-role</site-role>
    </vpn-attachment>
   </site-network-access>
  </site-network-accesses>
 </site>
 <site>
  <site-id>Office3</site-id>
  <site-network-accesses>
   <site-network-access>
    <site-network-access-id>1</site-network-access-id>
    <access-diversity>
     <groups>
      <group>
       <group-id>10</group-id>
      </group>
     </groups>
     <constraints>
      <constraint>
       <constraint-type>pop-diverse</constraint-type>
       <target>
        <group>
         <group-id>20</group-id>
        </group>
       </target>
      </constraint>

Litkowski, et al. Standards Track [Page 55] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

      <constraint>
       <constraint-type>linecard-diverse</constraint-type>
       <target>
        <group>
         <group-id>10</group-id>
        </group>
       </target>
      </constraint>
     </constraints>
    </access-diversity>
    <vpn-attachment>
     <vpn-id>VPNA</vpn-id>
     <site-role>spoke-role</site-role>
    </vpn-attachment>
   </site-network-access>
  </site-network-accesses>
 </site>
 <site>
  <site-id>Office4</site-id>
  <site-network-accesses>
   <site-network-access>
    <site-network-access-id>1</site-network-access-id>
    <access-diversity>
     <groups>
      <group>
       <group-id>20</group-id>
      </group>
     </groups>
     <constraints>
      <constraint>
       <constraint-type>pop-diverse</constraint-type>
       <target>
        <group>
         <group-id>10</group-id>
        </group>
       </target>
      </constraint>
      <constraint>
       <constraint-type>linecard-diverse</constraint-type>
       <target>
        <group>
         <group-id>20</group-id>
        </group>
       </target>
      </constraint>
     </constraints>
    </access-diversity>

Litkowski, et al. Standards Track [Page 56] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

    <vpn-attachment>
     <vpn-id>VPNA</vpn-id>
     <site-role>spoke-role</site-role>
    </vpn-attachment>
   </site-network-access>
  </site-network-accesses>
 </site>
 <site>
  <site-id>Office5</site-id>
  <site-network-accesses>
   <site-network-access>
    <site-network-access-id>1</site-network-access-id>
    <access-diversity>
     <groups>
      <group>
       <group-id>20</group-id>
      </group>
     </groups>
     <constraints>
      <constraint>
       <constraint-type>pop-diverse</constraint-type>
       <target>
        <group>
         <group-id>10</group-id>
        </group>
       </target>
      </constraint>
      <constraint>
       <constraint-type>linecard-diverse</constraint-type>
       <target>
        <group>
         <group-id>20</group-id>
        </group>
       </target>
      </constraint>
     </constraints>
    </access-diversity>
    <vpn-attachment>
     <vpn-id>VPNA</vpn-id>
     <site-role>spoke-role</site-role>
    </vpn-attachment>
   </site-network-access>
  </site-network-accesses>
 </site>

Litkowski, et al. Standards Track [Page 57] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 <site>
  <site-id>Office6</site-id>
  <site-network-accesses>
   <site-network-access>
    <site-network-access-id>1</site-network-access-id>
    <access-diversity>
     <groups>
      <group>
       <group-id>20</group-id>
      </group>
     </groups>
     <constraints>
      <constraint>
       <constraint-type>pop-diverse</constraint-type>
       <target>
        <group>
         <group-id>10</group-id>
        </group>
       </target>
      </constraint>
      <constraint>
       <constraint-type>linecard-diverse</constraint-type>
       <target>
        <group>
         <group-id>20</group-id>
        </group>
       </target>
      </constraint>
     </constraints>
    </access-diversity>
    <vpn-attachment>
     <vpn-id>VPNA</vpn-id>
     <site-role>spoke-role</site-role>
    </vpn-attachment>
   </site-network-access>
  </site-network-accesses>
 </site>

Litkowski, et al. Standards Track [Page 58] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

6.6.6.3. Parallel Links

 To increase its site bandwidth at lower cost, a customer wants to
 order two parallel site-network-accesses that will be connected to
 the same PE.
  • site-network-access#1

Site 1 *site-network-access#2 PE1

 This scenario can be expressed as follows:
 <site>
  <site-id>SITE1</site-id>
  <site-network-accesses>
   <site-network-access>
    <site-network-access-id>1</site-network-access-id>
    <access-diversity>
     <groups>
      <group>
       <group-id>PE-linkgrp-1</group-id>
      </group>
     </groups>
     <constraints>
      <constraint>
       <constraint-type>same-pe</constraint-type>
       <target>
        <group>
         <group-id>PE-linkgrp-1</group-id>
        </group>
       </target>
      </constraint>
     </constraints>
    </access-diversity>
    <vpn-attachment>
     <vpn-id>VPNB</vpn-id>
     <site-role>spoke-role</site-role>
    </vpn-attachment>
   </site-network-access>
   <site-network-access>
    <site-network-access-id>2</site-network-access-id>
    <access-diversity>
     <groups>
      <group>
       <group-id>PE-linkgrp-1</group-id>
      </group>
     </groups>

Litkowski, et al. Standards Track [Page 59] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

     <constraints>
      <constraint>
       <constraint-type>same-pe</constraint-type>
       <target>
        <group>
         <group-id>PE-linkgrp-1</group-id>
        </group>
       </target>
      </constraint>
     </constraints>
    </access-diversity>
    <vpn-attachment>
     <vpn-id>VPNB</vpn-id>
     <site-role>spoke-role</site-role>
    </vpn-attachment>
   </site-network-access>
  </site-network-accesses>
 </site>

6.6.6.4. SubVPN with Multihoming

 A customer has a site that is dual-homed.  The dual-homing must be
 done on two different PEs.  The customer also wants to implement two
 subVPNs on those multihomed accesses.
 +-----------------+         Site                     +------+
 |                 |---------------------------------/       +-----+
 |                 |****(site-network-access#1)*****| VPN B /       \
 | New York Office |****(site-network-access#2)************| VPN C   |
 |                 |                                  +-----\       /
 |                 |                                         +-----+
 |                 |
 |                 |                                  +------+
 |                 |                                 /       +-----+
 |                 |****(site-network-access#3)*****| VPN B /       \
 |                 |****(site-network-access#4)************| VPN C   |
 |                 |                                  +-----\       /
 |                 |-----------------------------------      +-----+
 +-----------------+
 This scenario can be expressed as follows:
 o  The site will have four site network accesses (two subVPNs coupled
    via dual-homing).
 o  Site-network-access#1 and site-network-access#3 will correspond to
    the multihoming of subVPN B.  A PE-diverse constraint is required
    between them.

Litkowski, et al. Standards Track [Page 60] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 o  Site-network-access#2 and site-network-access#4 will correspond to
    the multihoming of subVPN C.  A PE-diverse constraint is required
    between them.
 o  To ensure proper usage of the same bearer for the subVPN,
    site-network-access#1 and site-network-access#2 must share the
    same bearer as site-network-access#3 and site-network-access#4.
 <site>
  <site-id>SITE1</site-id>
  <site-network-accesses>
   <site-network-access>
    <site-network-access-id>1</site-network-access-id>
    <access-diversity>
     <groups>
      <group>
       <group-id>dualhomed-1</group-id>
      </group>
     </groups>
     <constraints>
      <constraint>
       <constraint-type>pe-diverse</constraint-type>
       <target>
        <group>
         <group-id>dualhomed-2</group-id>
        </group>
       </target>
      </constraint>
      <constraint>
       <constraint-type>same-bearer</constraint-type>
       <target>
        <group>
         <group-id>dualhomed-1</group-id>
        </group>
       </target>
      </constraint>
     </constraints>
    </access-diversity>
    <vpn-attachment>
     <vpn-id>VPNB</vpn-id>
     <site-role>spoke-role</site-role>
    </vpn-attachment>
   </site-network-access>
   <site-network-access>
    <site-network-access-id>2</site-network-access-id>
    <access-diversity>
     <groups>
      <group>

Litkowski, et al. Standards Track [Page 61] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

       <group-id>dualhomed-1</group-id>
      </group>
     </groups>
     <constraints>
      <constraint>
       <constraint-type>pe-diverse</constraint-type>
       <target>
        <group>
         <group-id>dualhomed-2</group-id>
        </group>
       </target>
      </constraint>
      <constraint>
       <constraint-type>same-bearer</constraint-type>
       <target>
        <group>
         <group-id>dualhomed-1</group-id>
        </group>
       </target>
      </constraint>
     </constraints>
    </access-diversity>
    <vpn-attachment>
     <vpn-id>VPNC</vpn-id>
     <site-role>spoke-role</site-role>
    </vpn-attachment>
   </site-network-access>
   <site-network-access>
    <site-network-access-id>3</site-network-access-id>
    <access-diversity>
     <groups>
      <group>
       <group-id>dualhomed-2</group-id>
      </group>
     </groups>
     <constraints>
      <constraint>
       <constraint-type>pe-diverse</constraint-type>
       <target>
        <group>
         <group-id>dualhomed-1</group-id>
        </group>
       </target>
      </constraint>
      <constraint>
       <constraint-type>same-bearer</constraint-type>
       <target>
        <group>

Litkowski, et al. Standards Track [Page 62] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

         <group-id>dualhomed-2</group-id>
        </group>
       </target>
      </constraint>
     </constraints>
    </access-diversity>
    <vpn-attachment>
     <vpn-id>VPNB</vpn-id>
     <site-role>spoke-role</site-role>
    </vpn-attachment>
   </site-network-access>
   <site-network-access>
    <site-network-access-id>4</site-network-access-id>
    <access-diversity>
     <groups>
      <group>
       <group-id>dualhomed-2</group-id>
      </group>
     </groups>
     <constraints>
      <constraint>
       <constraint-type>pe-diverse</constraint-type>
       <target>
        <group>
         <group-id>dualhomed-1</group-id>
        </group>
       </target>
      </constraint>
      <constraint>
       <constraint-type>same-bearer</constraint-type>
       <target>
        <group>
         <group-id>dualhomed-2</group-id>
        </group>
       </target>
      </constraint>
     </constraints>
    </access-diversity>
    <vpn-attachment>
     <vpn-id>VPNC</vpn-id>
     <site-role>spoke-role</site-role>
    </vpn-attachment>
   </site-network-access>
  </site-network-accesses>
 </site>

Litkowski, et al. Standards Track [Page 63] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

6.6.7. Route Distinguisher and VRF Allocation

 The route distinguisher (RD) is a critical parameter of PE-based
 L3VPNs 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 VRF on
 the target PE and an RD for this VRF.
 If a VRF already exists on the target PE and the VRF fulfills the
 connectivity constraints for the site, there is no need to recreate
 another VRF, and the site MAY be meshed within this existing VRF.
 How the management system checks that an existing VRF fulfills the
 connectivity constraints for a site is out of scope for this
 document.
 If no such VRF exists on the target PE, the management system has to
 initiate the creation of a new VRF on the target PE and has to
 allocate a new RD for this new VRF.
 The management system MAY apply a per-VPN or per-VRF allocation
 policy for the RD, depending on the SP's policy.  In a per-VPN
 allocation policy, all VRFs (dispatched on multiple PEs) within a VPN
 will share the same RD value.  In a per-VRF model, all 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
 examples provided in Section 6.2.1.1 could be reused 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.

6.7. Site Network Access Availability

 A site may be multihomed, meaning that it has multiple
 site-network-access points.  Placement constraints defined in
 previous sections 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.

Litkowski, et al. Standards Track [Page 64] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 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 figure below describes 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)
 In the figure above, 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 be modeled.  Let's consider a Hub
 site with five accesses to the network (A1,A2,A3,A4,A5).  The
 customer wants to load-share its traffic on A1,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 to A4 are down, he 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 A1 OR A2 is down is not achievable.  But the
 authors believe that using the access-priority attribute will cover
 most of the deployment use cases and that the model can still be
 extended via augmentation to support additional use cases.

Litkowski, et al. Standards Track [Page 65] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

6.8. Traffic Protection

 The service model supports the ability to protect the traffic for a
 site.  Such protection provides a better level of availability in
 multihoming scenarios by, for example, using local-repair techniques
 in case of failures.  The associated level of service guarantee would
 be based on an agreement between the customer and the SP and is out
 of scope for this document.
               Site#1                            Site#2
           CE1 ----- PE1 -- P1            P3 -- PE3 ---- CE3
            |                              |             |
            |                              |             |
           CE2 ----- PE2 -- P2            P4 -- PE4 ---- CE4
                     /
                    /
           CE5 ----+
              Site#3
 In the figure above, we consider an IP VPN service with three sites,
 including two dual-homed sites (Site#1 and Site#2).  For dual-homed
 sites, we consider PE1-CE1 and PE3-CE3 as primary and PE2-CE2,PE4-CE4
 as backup for the example (even if protection also applies to
 load-sharing scenarios).
 In order to protect Site#2 against a failure, a user may set the
 "traffic-protection/enabled" leaf to true for Site#2.  How the
 traffic protection will be implemented is out of scope for this
 document.  However, in such a case, we could consider traffic coming
 from a remote site (Site#1 or Site#3), where the primary path would
 use PE3 as the egress PE.  PE3 may have preprogrammed a backup
 forwarding entry pointing to the backup path (through PE4-CE4) for
 all prefixes going through the PE3-CE3 link.  How the backup path is
 computed is out of scope for this document.  When the PE3-CE3 link
 fails, traffic is still received by PE3, but PE3 automatically
 switches traffic to the backup entry; the path will therefore be
 PE1-P1-(...)-P3-PE3-PE4-CE4 until the remote PEs reconverge and use
 PE4 as the egress PE.

6.9. Security

 The "security" container defines customer-specific security
 parameters for the site.  The security options supported in the model
 are limited but may be extended via augmentation.

Litkowski, et al. Standards Track [Page 66] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

6.9.1. Authentication

 The current model does not support any authentication parameters for
 the site connection, but such parameters may be added in the
 "authentication" container through augmentation.

6.9.2. Encryption

 Traffic encryption can be requested on the connection.  It may be
 performed at Layer 2 or Layer 3 by selecting the appropriate
 enumeration in the "layer" leaf.  For example, an SP may use IPsec
 when a customer requests Layer 3 encryption.  The encryption profile
 can be SP defined or customer specific.
 When an SP profile is used and a key (e.g., a pre-shared key) is
 allocated by the provider to be used by a customer, the SP should
 provide a way to communicate the key in a secured way to the
 customer.
 When a customer profile is used, the model supports only a pre-shared
 key for authentication, with the pre-shared key provided through the
 NETCONF or RESTCONF request.  A secure channel must be used to ensure
 that the pre-shared key cannot be intercepted.
 For security reasons, it may be necessary for the customer to change
 the pre-shared key on a regular basis.  To perform a key change, the
 user can ask the SP to change the pre-shared key by submitting a new
 pre-shared key for the site configuration (as shown below).  This
 mechanism might not be hitless.
 <site>
  <site-id>SITE1</site-id>
  <site-network-accesses>
   <site-network-access>
    <site-network-access-id>1</site-network-access-id>
    <security>
     <encryption-profile>
      <preshared-key>MY_NEW_KEY</preshared-key>
     </encryption-profile>
    </security>
   </site-network-access>
  </site-network-accesses>
 </site>

Litkowski, et al. Standards Track [Page 67] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 A hitless key-change mechanism may be added through augmentation.
 Other key-management methodologies may be added through augmentation.
 A "pki" container, which is empty, has been created to help with
 support of PKI through augmentation.

6.10. Management

 The model proposes three types of common management options:
 o  provider-managed: The CE router is managed only by the provider.
    In this model, the responsibility boundary between the SP and the
    customer is between the CE and the customer network.
 o  customer-managed: The CE router is managed only by the customer.
    In this model, the responsibility boundary between the SP and the
    customer is between the PE and the CE.
 o  co-managed: The CE router is primarily managed by the provider; in
    addition, the SP allows customers to access the CE for
    configuration/monitoring purposes.  In the co-managed mode, the
    responsibility boundary is the same as the responsibility boundary
    for the provider-managed model.
 Based on the management model, different security options MAY be
 derived.
 In the co-managed case, the model proposes some options to define the
 management address family (IPv4 or IPv6) and the associated
 management address.

6.11. Routing Protocols

 "routing-protocol" defines which routing protocol must be activated
 between the provider and the customer router.  The current model
 supports the following settings: bgp, rip, ospf, static, direct,
 and vrrp.
 The routing protocol defined applies at the provider-to-customer
 boundary.  Depending on how the management model is administered, it
 may apply to the PE-CE boundary or the CE-to-customer boundary.  In
 the case of a customer-managed site, the routing protocol defined
 will be activated between the PE and the CE router managed by the
 customer.  In the case of a provider-managed site, the routing
 protocol defined will be activated between the CE managed by the SP
 and the router or LAN belonging to the customer.  In this case, we
 expect the PE-CE routing to be configured based on the SP's rules, as
 both are managed by the same entity.

Litkowski, et al. Standards Track [Page 68] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

                             Rtg protocol
     192.0.2.0/24 ----- CE ----------------- PE1
                  Customer-managed site
           Rtg protocol
     Customer router ----- CE ----------------- PE1
                  Provider-managed site
 All the examples below will refer to a scenario for a customer-
 managed site.

6.11.1. Handling of Dual Stack

 All routing protocol types support dual stack by using the
 "address-family" leaf-list.
 Example of dual stack using the same routing protocol:
 <routing-protocols>
   <routing-protocol>
     <type>static</type>
     <static>
         <address-family>ipv4</address-family>
         <address-family>ipv6</address-family>
     </static>
   </routing-protocol>
 </routing-protocols>
 Example of dual stack using two different routing protocols:
 <routing-protocols>
   <routing-protocol>
     <type>rip</type>
     <rip>
         <address-family>ipv4</address-family>
     </rip>
   </routing-protocol>
   <routing-protocol>
     <type>ospf</type>
     <ospf>
         <address-family>ipv6</address-family>
     </ospf>
   </routing-protocol>
 </routing-protocols>

Litkowski, et al. Standards Track [Page 69] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

6.11.2. LAN Directly Connected to SP Network

 The routing protocol type "direct" SHOULD be used when a customer LAN
 is directly connected to the provider network and must be advertised
 in the IP VPN.
          LAN attached directly to provider network:
          192.0.2.0/24 ----- PE1
 In this case, the customer has a default route to the PE address.

6.11.3. LAN Directly Connected to SP Network with Redundancy

 The routing protocol type "vrrp" SHOULD be used and advertised in the
 IP VPN when
 o  the customer LAN is directly connected to the provider network,
    and
 o  LAN redundancy is expected.
       LAN attached directly to provider network with LAN redundancy:
         192.0.2.0/24 ------ PE1
                        |
                        +--- PE2
 In this case, the customer has a default route to the SP network.

6.11.4. Static Routing

 The routing protocol type "static" MAY be used when a customer LAN is
 connected to the provider network through a CE router and must be
 advertised in the IP VPN.  In this case, the static routes give next
 hops (nh) to the CE and to the PE.  The customer has a default route
 to the SP network.
                                 Static rtg
        192.0.2.0/24 ------ CE -------------- PE
                             |                |
                             |      Static route 192.0.2.0/24 nh CE
             Static route 0.0.0.0/0 nh PE

Litkowski, et al. Standards Track [Page 70] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

6.11.5. RIP Routing

 The routing protocol type "rip" MAY be used when a customer LAN is
 connected to the provider network through a CE router and must be
 advertised in the IP VPN.  For IPv4, the model assumes that RIP
 version 2 is used.
 In the case of dual-stack routing requested through this model, the
 management system will be responsible for configuring RIP (including
 the correct version number) and associated address families on
 network elements.
                                 RIP rtg
         192.0.2.0/24 ------ CE -------------- PE

6.11.6. OSPF Routing

 The routing protocol type "ospf" MAY be used when a customer LAN is
 connected to the provider network through a CE router and must be
 advertised in the IP VPN.
 It can be used to extend an existing OSPF network and interconnect
 different areas.  See [RFC4577] for more details.
                           +---------------------+
                           |                     |
                   OSPF    |                     | OSPF
                   area 1  |                     | area 2
  (OSPF                    |                     |          (OSPF
  area 1) --- CE ---------- PE               PE ----- CE --- area 2)
                           |                     |
                           +---------------------+
 The model also proposes an option to create an OSPF sham link between
 two sites sharing the same area and having a backdoor link.  The
 sham link is created by referencing the target site sharing the same
 OSPF area.  The management system will be responsible for checking to
 see if there is already a sham link configured for this VPN and area
 between the same pair of PEs.  If there is no existing sham link, the
 management system will provision one.  This sham link MAY be reused
 by other sites.

Litkowski, et al. Standards Track [Page 71] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

                         +------------------------+
                         |                        |
                         |                        |
                         |  PE (--sham link--)PE  |
                         |    |                |  |
                         +----|----------------|--+
                              | OSPF area 1    | OSPF area 1
                              |                |
                              CE1             CE2
                              |                |
                        (OSPF area 1)     (OSPF area 1)
                              |                |
                              +----------------+
 Regarding dual-stack support, the user MAY specify both IPv4 and IPv6
 address families, if both protocols should be routed through OSPF.
 As OSPF uses separate protocol instances for IPv4 and IPv6, the
 management system will need to configure both OSPF version 2 and OSPF
 version 3 on the PE-CE link.
 Example of OSPF routing parameters in the service model:
 <routing-protocols>
   <routing-protocol>
     <type>ospf</type>
     <ospf>
         <area-address>0.0.0.1</area-address>
         <address-family>ipv4</address-family>
         <address-family>ipv6</address-family>
     </ospf>
   </routing-protocol>
 </routing-protocols>
 Example of PE configuration done by the management system:
 router ospf 10
  area 0.0.0.1
   interface Ethernet0/0
 !
 router ospfv3 10
  area 0.0.0.1
   interface Ethernet0/0
  !

Litkowski, et al. Standards Track [Page 72] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

6.11.7. BGP Routing

 The routing protocol type "bgp" MAY be used when a customer LAN is
 connected to the provider network through a CE router and must be
 advertised in the IP VPN.
                                 BGP rtg
       192.0.2.0/24 ------ CE -------------- PE
 The session addressing will be derived from connection parameters as
 well as the SP's knowledge of the addressing plan that is in use.
 In the case of dual-stack access, the user MAY request BGP routing
 for both IPv4 and IPv6 by specifying both address families.  It will
 be up to the SP and management system to determine how to decline the
 configuration (two BGP sessions, single, multi-session, etc.).
 The service configuration below activates BGP on the PE-CE link for
 both IPv4 and IPv6.
 BGP activation requires the SP to know the address of the customer
 peer.  The "static-address" allocation type for the IP connection
 MUST be used.
 <routing-protocols>
   <routing-protocol>
     <type>bgp</type>
     <bgp>
         <autonomous-system>65000</autonomous-system>
         <address-family>ipv4</address-family>
         <address-family>ipv6</address-family>
     </bgp>
   </routing-protocol>
 </routing-protocols>

Litkowski, et al. Standards Track [Page 73] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 Depending on the SP flavor, a management system can divide this
 service configuration into different flavors, as shown by the
 following examples.
 Example of PE configuration done by the management system
 (single IPv4 transport session):
 router bgp 100
  neighbor 203.0.113.2 remote-as 65000
  address-family ipv4 vrf Cust1
     neighbor 203.0.113.2 activate
  address-family ipv6 vrf Cust1
     neighbor 203.0.113.2 activate
     neighbor 203.0.113.2 route-map SET-NH-IPV6 out
 Example of PE configuration done by the management system
 (two sessions):
 router bgp 100
  neighbor 203.0.113.2 remote-as 65000
  neighbor 2001::2 remote-as 65000
  address-family ipv4 vrf Cust1
     neighbor 203.0.113.2 activate
  address-family ipv6 vrf Cust1
     neighbor 2001::2 activate
 Example of PE configuration done by the management system
 (multi-session):
 router bgp 100
  neighbor 203.0.113.2 remote-as 65000
  neighbor 203.0.113.2 multisession per-af
  address-family ipv4 vrf Cust1
     neighbor 203.0.113.2 activate
  address-family ipv6 vrf Cust1
     neighbor 203.0.113.2 activate
     neighbor 203.0.113.2 route-map SET-NH-IPV6 out

Litkowski, et al. Standards Track [Page 74] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

6.12. Service

 The service defines service parameters associated with the site.

6.12.1. Bandwidth

 The service bandwidth refers to the bandwidth requirement between the
 PE and the CE (WAN link bandwidth).  The requested bandwidth is
 expressed as svc-input-bandwidth and svc-output-bandwidth in bits
 per second.  The input/output direction uses the customer site as a
 reference: "input bandwidth" means download bandwidth for the site,
 and "output bandwidth" means upload bandwidth for the site.
 The service bandwidth is only configurable at the site-network-access
 level.
 Using a different input and output bandwidth will allow the SP to
 determine if the customer allows for asymmetric bandwidth access,
 such as ADSL.  It can also be used to set rate-limiting in a
 different way for uploading and downloading on a symmetric bandwidth
 access.
 The bandwidth is a service bandwidth expressed primarily as IP
 bandwidth, but if the customer enables MPLS for Carriers' Carriers
 (CsC), this becomes MPLS bandwidth.

6.12.2. QoS

 The model proposes to define QoS parameters in an abstracted way:
 o  qos-classification-policy: policy that defines a set of ordered
    rules to classify customer traffic.
 o  qos-profile: QoS scheduling profile to be applied.

6.12.2.1. QoS Classification

 QoS classification rules are handled by the
 "qos-classification-policy" container.  The qos-classification-policy
 container is an ordered list of rules that match a flow or
 application and set the appropriate target class of service
 (target-class-id).  The user can define the match using an
 application reference or a flow definition that is more specific
 (e.g., based on Layer 3 source and destination addresses, Layer 4
 ports, and Layer 4 protocol).  When a flow definition is used, the
 user can employ a "target-sites" leaf-list to identify the
 destination of a flow rather than using destination IP addresses.  In
 such a case, an association between the site abstraction and the IP

Litkowski, et al. Standards Track [Page 75] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 addresses used by this site must be done dynamically.  How this
 association is done is out of scope for this document; an
 implementation might not support this criterion and should advertise
 a deviation in this case.  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.
 The current 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.
 Where the classification is done depends on the SP's implementation
 of the service, but classification concerns the flow coming from the
 customer site and entering the network.
                                Provider network
                           +-----------------------+
    192.0.2.0/24
 198.51.100.0/24 ---- CE --------- PE
   Traffic flow
  ---------->
 In the figure above, the management system should implement the
 classification rule:
 o  in the ingress direction on the PE interface, if the CE is
    customer-managed.
 o  in the ingress direction on the CE interface connected to the
    customer LAN, if the CE is provider-managed.

Litkowski, et al. Standards Track [Page 76] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 The figure below describes a sample service description of QoS
 classification for a site:
 <service>
   <qos>
     <qos-classification-policy>
       <rule>
         <id>1</id>
         <match-flow>
           <ipv4-src-prefix>192.0.2.0/24</ipv4-src-prefix>
           <ipv4-dst-prefix>203.0.113.1/32</ipv4-dst-prefix>
           <l4-dst-port>80</l4-dst-port>
           <l4-protocol>tcp</l4-protocol>
         </match-flow>
         <target-class-id>DATA2</target-class-id>
       </rule>
       <rule>
         <id>2</id>
         <match-flow>
           <ipv4-src-prefix>192.0.2.0/24</ipv4-src-prefix>
           <ipv4-dst-prefix>203.0.113.1/32</ipv4-dst-prefix>
           <l4-dst-port>21</l4-dst-port>
           <l4-protocol>tcp</l4-protocol>
         </match-flow>
         <target-class-id>DATA2</target-class-id>
       </rule>
       <rule>
         <id>3</id>
         <match-application>p2p</match-application>
         <target-class-id>DATA3</target-class-id>
       </rule>
       <rule>
         <id>4</id>
         <target-class-id>DATA1</target-class-id>
       </rule>
     </qos-classification-policy>
   </qos>
 </service>
 In the example above:
 o  HTTP traffic from the 192.0.2.0/24 LAN destined for 203.0.113.1/32
    will be classified in DATA2.
 o  FTP traffic from the 192.0.2.0/24 LAN destined for 203.0.113.1/32
    will be classified in DATA2.

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 o  Peer-to-peer traffic will be classified in DATA3.
 o  All other traffic will be classified in DATA1.
 The order of rules is very important.  The management system
 responsible for translating those rules in network element
 configuration MUST keep the same processing order in network element
 configuration.  The order of rules is defined by the "id" leaf.  The
 lowest id MUST be processed first.

6.12.2.2. QoS Profile

 The user can choose either a standard profile provided by the
 operator or a custom profile.  The "qos-profile" container defines
 the traffic-scheduling policy to be used by the SP.
                                Provider network
                           +-----------------------+
 192.0.2.0/24
 198.51.100.0/24 ---- CE --------- PE
                         \       /
                        qos-profile
 In the case of a provider-managed or co-managed connection, 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 a customer-
 managed connection, the provider is only responsible for ensuring
 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.
 A custom QoS profile is defined as a list of classes of services and
 associated properties.  The properties are:
 o  rate-limit: used to rate-limit the class of service.  The value is
    expressed as a percentage of the global service bandwidth.  When
    the qos-profile container is implemented on the CE side,
    svc-output-bandwidth is taken into account as a reference.  When
    it is implemented on the PE side, svc-input-bandwidth is used.
 o  latency: used to define the latency constraint of the class.  The
    latency constraint can be expressed as the lowest possible latency
    or a latency boundary expressed in milliseconds.  How this latency
    constraint will be fulfilled is up to the SP's implementation of

Litkowski, et al. Standards Track [Page 78] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

    the service: a strict priority queuing may be used on the access
    and in the core network, and/or a low-latency routing
    configuration may be created for this traffic class.
 o  jitter: used to define the jitter constraint of the class.  The
    jitter constraint can be expressed as the lowest possible jitter
    or a jitter boundary expressed in microseconds.  How this jitter
    constraint will be fulfilled is up to the SP's implementation of
    the service: a strict priority queuing may be used on the access
    and in the core network, and/or a jitter-aware routing
    configuration may be created for this traffic class.
 o  bandwidth: used to define a guaranteed amount of bandwidth for the
    class of service.  It is expressed as a percentage.  The
    "guaranteed-bw-percent" parameter uses available bandwidth as a
    reference.  When the qos-profile container is implemented on the
    CE side, svc-output-bandwidth is taken into account as a
    reference.  When it is implemented on the PE side,
    svc-input-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
    reservation, controller reservation) is out of scope for this
    document.
 Some constraints may not be offered by an SP; in this case, a
 deviation should be advertised.  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.
 Example of service configuration using a standard QoS profile:
 <site-network-access>
  <site-network-access-id>1245HRTFGJGJ154654</site-network-access-id>
  <service>
   <svc-input-bandwidth>100000000</svc-input-bandwidth>
   <svc-output-bandwidth>100000000</svc-output-bandwidth>
   <qos>
    <qos-profile>
     <profile>PLATINUM</profile>
    </qos-profile>
   </qos>
  </service>

Litkowski, et al. Standards Track [Page 79] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 </site-network-access>
 <site-network-access>
  <site-network-access-id>555555AAAA2344</site-network-access-id>
  <service>
   <svc-input-bandwidth>2000000</svc-input-bandwidth>
   <svc-output-bandwidth>2000000</svc-output-bandwidth>
   <qos>
    <qos-profile>
     <profile>GOLD</profile>
    </qos-profile>
   </qos>
  </service>
 </site-network-access>
 Example of service configuration using a custom QoS profile:
 <site-network-access>
  <site-network-access-id>Site1</site-network-access-id>
  <service>
   <svc-input-bandwidth>100000000</svc-input-bandwidth>
   <svc-output-bandwidth>100000000</svc-output-bandwidth>
   <qos>
    <qos-profile>
     <classes>
      <class>
       <class-id>REAL_TIME</class-id>
       <rate-limit>10</rate-limit>
       <latency>
        <use-lowest-latency/>
       </latency>
      </class>
      <class>
       <class-id>DATA1</class-id>
       <latency>
        <latency-boundary>70</latency-boundary>
       </latency>
       <bandwidth>
        <guaranteed-bw-percent>80</guaranteed-bw-percent>
       </bandwidth>
      </class>
      <class>
       <class-id>DATA2</class-id>
       <latency>
        <latency-boundary>200</latency-boundary>
       </latency>
       <bandwidth>
        <guaranteed-bw-percent>5</guaranteed-bw-percent>
        <end-to-end/>

Litkowski, et al. Standards Track [Page 80] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

       </bandwidth>
      </class>
     </classes>
    </qos-profile>
   </qos>
  </service>
 </site-network-access>
 The custom QoS profile for Site1 defines a REAL_TIME class with a
 latency constraint expressed as the lowest possible latency.  It also
 defines two data classes -- DATA1 and DATA2.  The two classes express
 a latency boundary constraint as well as a bandwidth reservation, as
 the REAL_TIME class is rate-limited to 10% of the service bandwidth
 (10% of 100 Mbps = 10 Mbps).  In cases where congestion occurs, the
 REAL_TIME traffic can go up to 10 Mbps (let's assume that only 5 Mbps
 are consumed).  DATA1 and DATA2 will share the remaining bandwidth
 (95 Mbps) according to their percentage.  So, the DATA1 class will be
 served with at least 76 Mbps of bandwidth, while the DATA2 class will
 be served with at least 4.75 Mbps.  The latency boundary information
 of the data class may help the SP define a specific buffer tuning or
 a specific routing within the network.  The maximum percentage to be
 used is not limited by this model but MUST be limited by the
 management system according to the policies authorized by the SP.

6.12.3. Multicast

 The "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.  Users can also define the type of multicast relationship
 with the customer: router (requires a protocol such as PIM), host
 (IGMP or MLD), or both.  An address family (IPv4, IPv6, or both) can
 also be defined.

Litkowski, et al. Standards Track [Page 81] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

6.13. Enhanced VPN Features

6.13.1. Carriers' Carriers

 In the case of CsC [RFC4364], a customer may want to build an MPLS
 service using an IP VPN 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
 In the figure above, ISP1 resells an IP VPN service but has no core
 network infrastructure between its POPs.  ISP1 uses an IP VPN as the
 core network infrastructure (belonging to another provider) between
 its POPs.

Litkowski, et al. Standards Track [Page 82] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 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 signalling protocol.  This configuration is done at the site
 level.
 In the proposed model, LDP or BGP can be used as the MPLS signalling
 protocol.  In the case of LDP, an IGP routing protocol MUST also be
 activated.  In the case of BGP signalling, 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 IP MTU.

6.14. External ID References

 The service model sometimes refers to external information through
 identifiers.  As an example, to order a 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 REST 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 std-qos-profile, OAM profile-name, and
 provider-profile for encryption.
 How an SP provides the meanings of those identifiers to the customer
 is out of scope for this document.

6.15. Defining NNIs

 An autonomous system (AS) is a single network or group of networks
 that is controlled by a common system administration group and that
 uses a single, clearly defined routing protocol.  In some cases, VPNs
 need to span different ASes in different geographic 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 service seamlessly.
 o  an internal administrative boundary within a single SP (e.g.,
    backhaul versus core versus data center).
 NNIs (network-to-network interfaces) have to be defined to extend the
 VPNs across multiple ASes.

Litkowski, et al. Standards Track [Page 83] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 [RFC4364] defines multiple flavors of VPN NNI implementations.  Each
 implementation has pros and cons; this topic is outside the scope of
 this document.  For example, in an Inter-AS option A, autonomous
 system 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 unlabeled IP prefixes, they associate each interface with a
 VPN routing and forwarding (VRF) instance and a Border Gateway
 Protocol (BGP) session.  As a result, traffic between the
 back-to-back VRFs is IP.  In this scenario, the VPNs are isolated
 from each other, and because the traffic is IP, QoS mechanisms that
 operate on IP traffic can be applied to achieve customer service
 level agreements (SLAs).
  1. ——- ————– ———–

/ \ / \ / \

 | Cloud    |             |                |          |             |
 | Provider |-----NNI-----|                |----NNI---| Data Center |
 |  #1      |             |                |          |             |
  \        /              |                |           \           /
   --------               |                |            -----------
                          |                |
   --------               |   My network   |           -----------
  /        \              |                |          /           \
 | Cloud    |             |                |         |             |
 | Provider |-----NNI-----|                |---NNI---|  L3VPN      |
 |  #2      |             |                |         |  Partner    |
  \        /              |                |         |             |
   --------               |                |         |             |
                           \              /          |             |
                            --------------            \           /
                                  |                    -----------
                                  |
                                 NNI
                                  |
                                  |
                          -------------------
                         /                   \
                        |                     |
                        |                     |
                        |                     |
                        |     L3VPN Partner   |
                        |                     |
                         \                   /
                          -------------------

Litkowski, et al. Standards Track [Page 84] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 The figure above describes an SP network called "My network" that has
 several NNIs.  This network uses NNIs to:
 o  increase its footprint by relying on L3VPN partners.
 o  connect its own data center services to the customer IP VPN.
 o  enable the customer to access its private resources located in a
    private cloud owned by some CSPs.

6.15.1. Defining an NNI with the Option A Flavor

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

Litkowski, et al. Standards Track [Page 85] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 realized using the features of the current model.  As an example, the
 figure above shows two physical connections that have logical
 connections per VPN overlaid on them.  This could be seen as a
 dual-homed subVPN scenario.  Also, the administrator of AS B will be
 able to choose the appropriate routing protocol (e.g., E-BGP) to
 dynamically exchange routes between ASes.
 This document assumes that the option A NNI flavor SHOULD reuse the
 existing VPN site modeling.
 Example: a customer wants its CSP A to attach its virtual network N
 to an existing IP VPN (VPN1) that he has from L3VPN SP B.
         CSP A                              L3VPN SP B
  1. —————- ——————-

/ \ / \

 |       |           |                |                     |
 |  VM --|       ++++++++  NNI    ++++++++                  |--- VPN1
 |       |       +      +_________+      +                  |   Site#1
 |       |--------(VRF1)---(VPN1)--(VRF1)+                  |
 |       |       + ASBR +         + ASBR +                  |
 |       |       +      +_________+      +                  |
 |       |       ++++++++         ++++++++                  |
 |  VM --|           |                |                     |--- VPN1
 |       |Virtual    |                |                     |   Site#2
 |       |Network    |                |                     |
 |  VM --|           |                |                     |--- VPN1
 |       |           |                |                     |   Site#3
  \                 /                  \                   /
   -----------------                    -------------------
                                                |
                                                |
                                              VPN1
                                             Site#4
 To create the VPN connectivity, the CSP or the customer may use the
 L3VPN service model 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 the figure).  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:

Litkowski, et al. Standards Track [Page 86] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 <site>
     <site-id>CSP_A_attachment</site-id>
     <location>
         <city>NY</city>
         <country-code>US</country-code>
     </location>
     <site-vpn-flavor>site-vpn-flavor-nni</site-vpn-flavor>
     <routing-protocols>
       <routing-protocol>
         <type>bgp</type>
         <bgp>
             <autonomous-system>500</autonomous-system>
             <address-family>ipv4</address-family>
         </bgp>
       </routing-protocol>
     </routing-protocols>
     <site-network-accesses>
      <site-network-access>
       <site-network-access-id>CSP_A_VN1</site-network-access-id>
        <ip-connection>
         <ipv4>
          <address-allocation-type>
          static-address
          </address-allocation-type>
          <addresses>
           <provider-address>203.0.113.1</provider-address>
           <customer-address>203.0.113.2</customer-address>
           <mask>30</mask>
          </addresses>
         </ipv4>
        </ip-connection>
        <service>
         <svc-input-bandwidth>450000000</svc-input-bandwidth>
         <svc-output-bandwidth>450000000</svc-output-bandwidth>
        </service>
        <vpn-attachment>
         <vpn-id>VPN1</vpn-id>
         <site-role>any-to-any-role</site-role>
        </vpn-attachment>
      </site-network-access>
     </site-network-accesses>
     <management>
         <type>customer-managed</type>
     </management>
 </site>

Litkowski, et al. Standards Track [Page 87] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 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.

6.15.2. 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 +                 |
 |                 +      +               +      +                 |
 |                 +      +_______________+      +                 |
 |                 ++++++++               ++++++++                 |
 |                     |                     |                     |
 |                     |                     |                     |
  \                   /                       \                   /
   -------------------                         -------------------
 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 [RFC4760].
 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.

Litkowski, et al. Standards Track [Page 88] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 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.
 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
  1. —————- ——————

/ \ / \

 |       |           |                |                    |
 |  VM --|       ++++++++   NNI    ++++++++                |--- VPN1
 |       |       +      +__________+      +                |   Site#1
 |       |-------+      +          +      +                |
 |       |       + ASBR +<-MP-BGP->+ ASBR +                |
 |       |       +      +__________+      +                |
 |       |       ++++++++          ++++++++                |
 |  VM --|           |                |                    |--- VPN1
 |       |Virtual    |                |                    |   Site#2
 |       |Network    |                |                    |
 |  VM --|           |                |                    |--- VPN1
 |       |           |                |                    |   Site#3
  \                 /                 |                    |
   -----------------                  |                    |
                                       \                  /
                                        ------------------
                                                 |
                                                 |
                                                VPN1
                                               Site#4

Litkowski, et al. Standards Track [Page 89] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 The example above describes an NNI connection between CSP A and SP
 network B.  Both SPs do not trust themselves and use a different RT
 allocation policy.  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 virtual network in
 CSP A to the customer IP VPN (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.

Litkowski, et al. Standards Track [Page 90] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

6.15.3. Defining an NNI with the Option C Flavor

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

Litkowski, et al. Standards Track [Page 91] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 From a VPN service's point of view, modeling options B and C will be
 identical.

7. Service Model Usage Example

 As explained in Section 5, 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 IP VPN service on network elements.
 In this example, we want to achieve the provisioning of a VPN service
 for three sites using a Hub-and-Spoke VPN service topology.  One of
 the sites will be dual-homed, and load-sharing is expected.
 +-------------------------------------------------------------+
 |   Hub_Site  ------ PE1               PE2 ------ Spoke_Site1 |
 |      |                   +----------------------------------+
 |      |                   |
 |      |                   +----------------------------------+
 |   Hub_Site  ------ PE3               PE4 ------ Spoke_Site2 |
 +-------------------------------------------------------------+
 The following XML describes the overall simplified service
 configuration of this VPN.
 <vpn-service>
     <vpn-id>12456487</vpn-id>
     <vpn-service-topology>hub-spoke</vpn-service-topology>
 </vpn-service>

Litkowski, et al. Standards Track [Page 92] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 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 Hub and 100:2 for Spoke).  The
 output below describes the configuration of Spoke_Site1.
 <site>
     <site-id>Spoke_Site1</site-id>
     <location>
         <city>NY</city>
         <country-code>US</country-code>
     </location>
     <routing-protocols>
       <routing-protocol>
         <type>bgp</type>
         <bgp>
             <autonomous-system>500</autonomous-system>
             <address-family>ipv4</address-family>
             <address-family>ipv6</address-family>
         </bgp>
       </routing-protocol>
     </routing-protocols>
     <site-network-accesses>
      <site-network-access>
       <site-network-access-id>Spoke_Site1</site-network-access-id>
       <access-diversity>
        <groups>
         <group>
          <group-id>20</group-id>
         </group>
        </groups>
        <constraints>
         <constraint>
          <constraint-type>pe-diverse</constraint-type>
          <target>
           <group>
            <group-id>10</group-id>
           </group>
          </target>
         </constraint>
        </constraints>
       </access-diversity>
       <ip-connection>
         <ipv4>
          <address-allocation-type>
          static-address
          </address-allocation-type>

Litkowski, et al. Standards Track [Page 93] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

          <addresses>
           <provider-address>203.0.113.254</provider-address>
           <customer-address>203.0.113.2</customer-address>
           <mask>24</mask>
          </addresses>
         </ipv4>
         <ipv6>
          <address-allocation-type>
          static-address
          </address-allocation-type>
           <addresses>
            <provider-address>2001:db8::1</provider-address>
            <customer-address>2001:db8::2</customer-address>
            <mask>64</mask>
           </addresses>
         </ipv6>
       </ip-connection>
       <service>
         <svc-input-bandwidth>450000000</svc-input-bandwidth>
         <svc-output-bandwidth>450000000</svc-output-bandwidth>
       </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>
 When receiving the request for provisioning Spoke_Site1, the
 management system MUST allocate network resources for this site.  It
 MUST first determine the target network elements to provision the
 access, particularly the PE router (and perhaps also an aggregation
 switch).  As described in Section 6.6, the management system SHOULD
 use the location information and SHOULD use the access-diversity
 constraint to find the appropriate PE.  In this case, we consider
 that Spoke_Site1 requires PE diversity with the Hub and that the
 management system allocates PEs based on the least distance.  Based
 on the location information, the management system finds the
 available PEs in the area nearest the customer and picks one that
 fits the access-diversity constraint.

Litkowski, et al. Standards Track [Page 94] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 When the PE is chosen, the management system needs to allocate
 interface resources on the node.  One interface is selected from the
 pool of available PEs.  The management system can start provisioning
 the chosen PE node via whatever means the management system prefers
 (e.g., NETCONF, CLI).  The management system will check to see if a
 VRF that fits its needs is already present.  If not, it will
 provision the VRF: the RD will be derived from the internal
 allocation policy model, and the RTs will be derived from the VPN
 policy configuration of the site (the management system allocated
 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 generated PE configuration:
 ip vrf Customer1
  export-map STD-CUSTOMER-EXPORT      <---- Standard SP configuration
  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 VRF has been provisioned, the management system can start
 configuring the access on the PE using the allocated interface
 information.  IP addressing is chosen by the management system.  One
 address will be picked from an allocated subnet for the PE, and
 another will be used for the CE configuration.  Routing protocols
 will also be configured between the PE and CE; because this model is
 provider-managed, the choices are left to the SP.  BGP was chosen for
 this example.  This choice is independent of the routing protocol
 chosen by the customer.  BGP will be used to configure the CE-to-LAN
 connection as requested in the service model.  Peering addresses will
 be derived from those of the connection.  As the CE is provider-
 managed, the CE's AS number can be automatically allocated by the
 management system.  Standard configuration templates provided by the
 SP may also be added.

Litkowski, et al. Standards Track [Page 95] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 Example of generated PE configuration:
 interface Ethernet1/1/0.10
  encapsulation dot1q 10
  ip vrf forwarding Customer1
  ip address 198.51.100.1 255.255.255.252 <---- Comes from
                                                 automated allocation
  ipv6 address 2001:db8::10:1/64
  ip access-group STD-PROTECT-IN     <---- Standard SP config
 !
 router bgp 100
  address-family ipv4 vrf Customer1
   neighbor 198.51.100.2 remote-as 65000   <---- Comes from
                                                  automated allocation
   neighbor 198.51.100.2 route-map STD in  <---- Standard SP config
   neighbor 198.51.100.2 filter-list 10 in <---- Standard SP config
 !
  address-family ipv6 vrf Customer1
   neighbor 2001:db8::0a10:2 remote-as 65000   <---- Comes from
                                                  automated allocation
   neighbor 2001:db8::0a10:2 route-map STD in  <---- Standard SP
                                                        config
   neighbor 2001:db8::0a10:2 filter-list 10 in <---- Standard SP
                                                        config
 !
 ip route vrf Customer1 192.0.2.1 255.255.255.255 198.51.100.2
 ! Static route for provider administration of CE
 !
 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 before sending the CE configuration to the
 customer premises.  The CE configuration will be built in the same
 way as the PE would be configured.  Based on the CE type
 (vendor/model) allocated to the customer as well as the 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 OSS, as both resources are managed
 internally.  CE-to-LAN-interface parameters such as IP addressing are
 derived from the ip-connection container, taking into account how the
 management system distributes addresses between the PE and CE within
 the subnet.  This will allow a plug-and-play configuration for the CE
 to be created.

Litkowski, et al. Standards Track [Page 96] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 Example of generated CE configuration:
 interface Loopback10
  description "Administration"
  ip address 192.0.2.1 255.255.255.255
 !
 interface FastEthernet10
  description "WAN"
  ip address 198.51.100.2 255.255.255.252 <---- Comes from
                                                 automated allocation
  ipv6 address 2001:db8::0a10:2/64
 !
 interface FastEthernet11
  description "LAN"
  ip address 203.0.113.254 255.255.255.0 <---- Comes from the
                                             ip-connection container
  ipv6 address 2001:db8::1/64
 !
 router bgp 65000
  address-family ipv4
   redistribute static route-map STATIC2BGP <---- Standard SP
                                                     configuration
   neighbor 198.51.100.1 remote-as 100     <---- Comes from
                                               automated allocation
   neighbor 203.0.113.2 remote-as 500     <---- Comes from the
                                               ip-connection container
  address-family ipv6
   redistribute static route-map STATIC2BGP <---- Standard SP
                                                     configuration
   neighbor 2001:db8::0a10:1 remote-as 100     <---- Comes from
                                               automated allocation
   neighbor 2001:db8::2 remote-as 500     <---- Comes from the
                                               ip-connection container
 !
 route-map STATIC2BGP permit 10
  match tag 10
 !

Litkowski, et al. Standards Track [Page 97] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

8. Interaction with Other YANG Modules

 As expressed in Section 5, this service model is intended to be
 instantiated in a management system and not directly on network
 elements.
 The management system's role will be to configure the network
 elements.  The management system may be modular, so the component
 instantiating the service model (let's call it "service component")
 and the component responsible for network element configuration
 (let's call it "configuration component") may be different.
           l3vpn-svc         |
             Model           |
                             |
                  +---------------------+
                  |  Service component  | Service datastore
                  +---------------------+
                             |
                             |
                  +---------------------+
             +----|  Config component   |------+
            /     +---------------------+       \   Network
           /            /            \           \  Configuration
          /            /              \           \ models
         /            /                \           \
 ++++++++         ++++++++           ++++++++       ++++++++
 + CE A + ------- + PE A +           + PE B + ----- + CE B + Config
 ++++++++         ++++++++           ++++++++       ++++++++ datastore
          Site A                              Site B
 In the previous sections, we provided some examples of the
 translation of service provisioning requests to router configuration
 lines.  In the NETCONF/YANG ecosystem, we expect NETCONF/YANG to be
 used between the configuration component and network elements to
 configure the requested services on those elements.
 In this framework, specifications are expected to provide specific
 YANG modeling of 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.

Litkowski, et al. Standards Track [Page 98] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 The authors of this document anticipate definitions of YANG models
 for the network elements listed below.  Note that this list is not
 exhaustive:
 o  VRF definition, including VPN policy expression.
 o  Physical interface.
 o  IP layer (IPv4, IPv6).
 o  QoS: classification, profiles, etc.
 o  Routing protocols: support of configuration of all protocols
    listed in the document, as well as routing policies associated
    with those protocols.
 o  Multicast VPN.
 o  Network address translation.
 Example of a VPN site request at the service level, using this model:
 <site>
  <site-id>Site A</site-id>
  <site-network-accesses>
   <site-network-access>
    <ip-connection>
     <ipv4>
      <address-allocation-type>
      static-address
      </address-allocation-type>
      <addresses>
       <provider-address>203.0.113.254</provider-address>
       <customer-address>203.0.113.2</customer-address>
       <mask>24</mask>
      </addresses>
     </ipv4>
    </ip-connection>
    <vpn-attachment>
     <vpn-policy-id>VPNPOL1</vpn-policy-id>
    </vpn-attachment>
   </site-network-access>
  </site-network-accesses>

Litkowski, et al. Standards Track [Page 99] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

  <routing-protocols>
   <routing-protocol>
    <type>static</type>
    <static>
     <cascaded-lan-prefixes>
      <ipv4-lan-prefixes>
       <lan>198.51.100.0/30</lan>
       <next-hop>203.0.113.2</next-hop>
      </ipv4-lan-prefixes>
     </cascaded-lan-prefixes>
    </static>
   </routing-protocol>
  </routing-protocols>
  <management>
   <type>customer-managed</type>
  </management>
  <vpn-policies>
   <vpn-policy>
    <vpn-policy-id>VPNPOL1</vpn-policy-id>
    <entries>
     <id>1</id>
      <vpn>
       <vpn-id>VPN1</vpn-id>
       <site-role>any-to-any-role</site-role>
      </vpn>
     </entries>
   </vpn-policy>
  </vpn-policies>
 </site>
 In the service example above, the service component is expected to
 request that the configuration component of the management system
 provide the configuration of the service elements.  If we consider
 that the service component selected a PE (PE A) as the target PE for
 the site, the configuration component will need to push the
 configuration to PE A.  The configuration component will use several
 YANG data models to define the configuration to be applied to PE A.
 The XML configuration of PE A might look like this:
 <if:interfaces>
      <if:interface>
       <if:name>eth0</if:name>
       <if:type>ianaift:ethernetCsmacd</if:type>
       <if:description>
        Link to CE A.
       </if:description>
       <ip:ipv4>
        <ip:address>

Litkowski, et al. Standards Track [Page 100] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

         <ip:ip>203.0.113.254</ip:ip>
         <ip:prefix-length>24</ip:prefix-length>
        </ip:address>
        <ip:forwarding>true</ip:forwarding>
       </ip:ipv4>
      </if:interface>
 </if:interfaces>
 <rt:routing>
     <rt:routing-instance>
       <rt:name>VRF_CustA</rt:name>
       <rt:type>l3vpn-network:vrf</rt:type>
       <rt:description>VRF for Customer A</rt:description>
       <l3vpn-network:route-distinguisher>
       100:1546542343
       </l3vpn-network:route-distinguisher>
       <l3vpn-network:import-rt>100:1</l3vpn-network:import-rt>
       <l3vpn-network:export-rt>100:1</l3vpn-network:export-rt>
       <rt:interfaces>
        <rt:interface>
         <rt:name>eth0</rt:name>
        </rt:interface>
       </rt:interfaces>
       <rt:routing-protocols>
        <rt:routing-protocol>
         <rt:type>rt:static</rt:type>
         <rt:name>st0</rt:name>
         <rt:static-routes>
          <v4ur:ipv4>
           <v4ur:route>
            <v4ur:destination-prefix>
            198.51.100.0/30
            </v4ur:destination-prefix>
            <v4ur:next-hop>
             <v4ur:next-hop-address>
             203.0.113.2
             </v4ur:next-hop-address>
            </v4ur:next-hop>
           </v4ur:route>
          </v4ur:ipv4>
         </rt:static-routes>
        </rt:routing-protocol>
       </rt:routing-protocols>
      </rt:routing-instance>
 </rt:routing>

Litkowski, et al. Standards Track [Page 101] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

9. YANG Module

 <CODE BEGINS>
 file "ietf-l3vpn-svc@2017-01-27.yang"
 module ietf-l3vpn-svc {
  namespace "urn:ietf:params:xml:ns:yang:ietf-l3vpn-svc";
  prefix l3vpn-svc;
  import ietf-inet-types {
   prefix inet;
  }
  import ietf-yang-types {
   prefix yang;
  }
  organization
   "IETF L3SM Working Group";
  contact
   "WG List: <mailto:l3sm@ietf.org>
   Editor:
    L3SM WG
   Chairs:
    Adrian Farrel, Qin Wu
   ";
  description
   "This YANG module defines a generic service configuration
   model for Layer 3 VPNs.  This model is common across all
   vendor implementations.";
  revision 2017-01-27 {
   description
    "Initial document.";
   reference
     "RFC 8049.";
  }

Litkowski, et al. Standards Track [Page 102] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

  /* Features */
  feature cloud-access {
   description
    "Allows the VPN to connect to a CSP.";
  }
  feature multicast {
   description
    "Enables multicast capabilities in a VPN.";
  }
  feature ipv4 {
   description
    "Enables IPv4 support in a VPN.";
  }
  feature ipv6 {
   description
    "Enables IPv6 support in a VPN.";
  }
  feature carrierscarrier {
   description
    "Enables support of CsC.";
  }
  feature extranet-vpn {
   description
    "Enables support of extranet VPNs.";
  }
  feature site-diversity {
   description
    "Enables support of site diversity constraints.";
  }
  feature encryption {
   description
    "Enables support of encryption.";
  }
  feature qos {
   description
    "Enables support of classes of services.";
  }
  feature qos-custom {
   description
    "Enables support of the custom QoS profile.";
  }
  feature rtg-bgp {
   description
    "Enables support of the BGP routing protocol.";
  }

Litkowski, et al. Standards Track [Page 103] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

  feature rtg-rip {
   description
    "Enables support of the RIP routing protocol.";
  }
  feature rtg-ospf {
   description
    "Enables support of the OSPF routing protocol.";
  }
  feature rtg-ospf-sham-link {
   description
    "Enables support of OSPF sham links.";
  }
  feature rtg-vrrp {
   description
    "Enables support of the VRRP routing protocol.";
  }
  feature fast-reroute {
   description
    "Enables support of Fast Reroute.";
  }
  feature bfd {
   description
    "Enables support of BFD.";
  }
  feature always-on {
   description
    "Enables support of the 'always-on' access constraint.";
  }
  feature requested-type {
   description
    "Enables support of the 'requested-type' access constraint.";
  }
  feature bearer-reference {
   description
    "Enables support of the 'bearer-reference' access constraint.";
  }
  /* Typedefs */
  typedef svc-id {
   type string;
   description
    "Defines a type of service component identifier.";
  }

Litkowski, et al. Standards Track [Page 104] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

  typedef template-id {
   type string;
   description
    "Defines a type of service template identifier.";
  }
  typedef address-family {
   type enumeration {
    enum ipv4 {
     description
      "IPv4 address family.";
    }
    enum ipv6 {
     description
      "IPv6 address family.";
    }
   }
   description
    "Defines a type for the address family.";
  }
  /* Identities */
  identity site-network-access-type {
   description
    "Base identity for site-network-access type.";
  }
  identity point-to-point {
   base site-network-access-type;
   description
    "Identity for point-to-point connection.";
  }
  identity multipoint {
   base site-network-access-type;
   description
    "Identity for multipoint connection.
    Example: Ethernet broadcast segment.";
  }
  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.";
  }

Litkowski, et al. Standards Track [Page 105] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

  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 customer-application {
   description
    "Base identity for customer application.";
  }
  identity web {
   base customer-application;
   description
    "Identity for Web application (e.g., HTTP, HTTPS).";
  }
  identity mail {
   base customer-application;
   description
    "Identity for mail application.";
  }
  identity file-transfer {
   base customer-application;
   description
    "Identity for file transfer application (e.g., FTP, SFTP).";
  }

Litkowski, et al. Standards Track [Page 106] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

  identity database {
   base customer-application;
   description
    "Identity for database application.";
  }
  identity social {
   base customer-application;
   description
    "Identity for social-network application.";
  }
  identity games {
   base customer-application;
   description
    "Identity for gaming application.";
  }
  identity p2p {
   base customer-application;
   description
    "Identity for peer-to-peer application.";
  }
  identity network-management {
   base customer-application;
   description
    "Identity for management application
    (e.g., Telnet, syslog, SNMP).";
  }
  identity voice {
   base customer-application;
   description
    "Identity for voice application.";
  }
  identity video {
   base customer-application;
   description
    "Identity for video conference application.";
  }
  identity site-vpn-flavor {
   description
    "Base identity for the site VPN service flavor.";
  }
  identity site-vpn-flavor-single {
   base site-vpn-flavor;
   description
    "Base identity for the site VPN service flavor.
    Used when the site belongs to only one VPN.";
  }

Litkowski, et al. Standards Track [Page 107] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

  identity site-vpn-flavor-multi {
   base site-vpn-flavor;
   description
    "Base identity for the site VPN service flavor.
    Used when a logical connection of a site
    belongs to multiple VPNs.";
  }
  identity site-vpn-flavor-sub {
   base site-vpn-flavor;
   description
    "Base identity for the site VPN service flavor.
    Used when a site has multiple logical connections.
    Each connection may belong to different multiple VPNs.";
  }
  identity site-vpn-flavor-nni {
   base site-vpn-flavor;
   description
    "Base identity for the site VPN service flavor.
    Used to describe an NNI option A connection.";
  }
  identity management {
   description
    "Base identity for site management scheme.";
  }
  identity co-managed {
   base management;
   description
    "Base identity for co-managed site.";
  }
  identity customer-managed {
   base management;
   description
    "Base identity for customer-managed site.";
  }
  identity provider-managed {
   base management;
   description
    "Base identity for provider-managed site.";
  }
  identity address-allocation-type {
   description
    "Base identity for address-allocation-type for PE-CE link.";
  }
  identity provider-dhcp {
   base address-allocation-type;
   description
    "Provider network provides DHCP service to customer.";
  }

Litkowski, et al. Standards Track [Page 108] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

  identity provider-dhcp-relay {
   base address-allocation-type;
   description
    "Provider network provides DHCP relay service to customer.";
  }
  identity provider-dhcp-slaac {
   base address-allocation-type;
   description
    "Provider network provides DHCP service to customer,
    as well as SLAAC.";
  }
  identity static-address {
   base address-allocation-type;
   description
    "Provider-to-customer addressing is static.";
  }
  identity slaac {
   base address-allocation-type;
   description
    "Use IPv6 SLAAC.";
  }
  identity site-role {
   description
    "Base identity for site type.";
  }
  identity any-to-any-role {
   base site-role;
   description
    "Site in an any-to-any IP VPN.";
  }
  identity spoke-role {
   base site-role;
   description
    "Spoke site in a Hub-and-Spoke IP VPN.";
  }
  identity hub-role {
   base site-role;
   description
    "Hub site in a Hub-and-Spoke IP VPN.";
  }

Litkowski, et al. Standards Track [Page 109] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

  identity vpn-topology {
   description
    "Base identity for VPN topology.";
  }
  identity any-to-any {
   base vpn-topology;
   description
    "Identity for any-to-any VPN topology.";
  }
  identity hub-spoke {
   base vpn-topology;
   description
    "Identity for Hub-and-Spoke VPN topology.";
  }
  identity hub-spoke-disjoint {
   base vpn-topology;
   description
    "Identity for Hub-and-Spoke VPN topology
    where Hubs cannot communicate with each other.";
  }
  identity multicast-tree-type {
   description
    "Base identity for multicast tree type.";
  }
  identity ssm-tree-type {
   base multicast-tree-type;
   description
    "Identity for SSM tree type.";
  }
  identity asm-tree-type {
   base multicast-tree-type;
   description
    "Identity for ASM tree type.";
  }
  identity bidir-tree-type {
   base multicast-tree-type;
   description
    "Identity for bidirectional tree type.";
  }
  identity multicast-rp-discovery-type {
   description
    "Base identity for RP discovery type.";
  }

Litkowski, et al. Standards Track [Page 110] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

  identity auto-rp {
   base multicast-rp-discovery-type;
   description
    "Base identity for Auto-RP discovery type.";
  }
  identity static-rp {
   base multicast-rp-discovery-type;
   description
    "Base identity for static type.";
  }
  identity bsr-rp {
   base multicast-rp-discovery-type;
   description
    "Base identity for BSR discovery type.";
  }
  identity routing-protocol-type {
   description
    "Base identity for routing protocol type.";
  }
  identity ospf {
   base routing-protocol-type;
   description
    "Identity for OSPF protocol type.";
  }
  identity bgp {
   base routing-protocol-type;
   description
    "Identity for BGP protocol type.";
  }
  identity static {
   base routing-protocol-type;
   description
    "Identity for static routing protocol type.";
  }
  identity rip {
   base routing-protocol-type;
   description
    "Identity for RIP protocol type.";
  }
  identity vrrp {
   base routing-protocol-type;
   description
    "Identity for VRRP protocol type.
    This is to be used when LANs are directly connected
    to PE routers.";
  }

Litkowski, et al. Standards Track [Page 111] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

  identity direct {
   base routing-protocol-type;
   description
    "Identity for direct protocol type.";
  }
  identity protocol-type {
   description
    "Base identity for protocol field type.";
  }
  identity tcp {
   base protocol-type;
   description
    "TCP protocol type.";
  }
  identity udp {
   base protocol-type;
   description
    "UDP protocol type.";
  }
  identity icmp {
   base protocol-type;
   description
    "ICMP protocol type.";
  }
  identity icmp6 {
   base protocol-type;
   description
    "ICMPv6 protocol type.";
  }
  identity gre {
   base protocol-type;
   description
    "GRE protocol type.";
  }
  identity ipip {
   base protocol-type;
   description
    "IP-in-IP protocol type.";
  }
  identity hop-by-hop {
   base protocol-type;
   description
    "Hop-by-Hop IPv6 header type.";
  }

Litkowski, et al. Standards Track [Page 112] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

  identity routing {
   base protocol-type;
   description
    "Routing IPv6 header type.";
  }
  identity esp {
   base protocol-type;
   description
    "ESP header type.";
  }
  identity ah {
   base protocol-type;
   description
    "AH header type.";
  }
  /* Groupings */
  grouping vpn-service-cloud-access {
   container cloud-accesses {
   if-feature cloud-access;
   list cloud-access {
    key cloud-identifier;
    leaf cloud-identifier {
     type string;
     description
      "Identification of cloud service.
      Local administration meaning.";
    }
    choice list-flavor {
     case permit-any {
      leaf permit-any {
       type empty;
       description
        "Allows all sites.";
      }
     }
     case deny-any-except {
      leaf-list permit-site {
       type leafref {
        path "/l3vpn-svc/sites/site/site-id";
       }
       description
        "Site ID to be authorized.";
      }
     }

Litkowski, et al. Standards Track [Page 113] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

     case permit-any-except {
      leaf-list deny-site {
       type leafref {
        path "/l3vpn-svc/sites/site/site-id";
       }
       description
        "Site ID to be denied.";
      }
     }
     description
      "Choice for cloud access policy.";
    }
    container authorized-sites {
     list authorized-site {
      key site-id;
      leaf site-id {
       type leafref {
        path "/l3vpn-svc/sites/site/site-id";
       }
       description
        "Site ID.";
      }
      description
       "List of authorized sites.";
     }
     description
      "Configuration of authorized sites.";
    }
    container denied-sites {
     list denied-site {
      key site-id;
      leaf site-id {
       type leafref {
        path "/l3vpn-svc/sites/site/site-id";
       }
       description
        "Site ID.";
      }
      description
       "List of denied sites.";
     }
     description
      "Configuration of denied sites.";
    }

Litkowski, et al. Standards Track [Page 114] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

    container address-translation {
     container nat44 {
      leaf enabled {
       type boolean;
       default false;
       description
        "Controls whether or not address translation is required.";
      }
      leaf nat44-customer-address {
       type inet:ipv4-address;
       must "../enabled = 'true'" {
        description
         "Applicable only if address translation is enabled.";
       }
       description
        "Address to be used for translation.
        This is to be used if the customer is
        providing the address.";
      }
      description
       "IPv4-to-IPv4 translation.";
     }
     description
      "Container for NAT.";
    }
    description
     "Cloud access configuration.";
   }
    description
     "Container for cloud access configurations.";
   }
   description
    "Grouping for VPN cloud definition.";
  }

Litkowski, et al. Standards Track [Page 115] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

  grouping multicast-rp-group-cfg {
   choice group-format {
    case startend {
     leaf group-start {
      type inet:ip-address;
      description
       "First group address.";
     }
     leaf group-end {
      type inet:ip-address;
      description
       "Last group address.";
     }
    }
    case singleaddress {
     leaf group-address {
      type inet:ip-address;
      description
       "Group address.";
     }
    }
    description
     "Choice for group format.";
   }
   description
    "Definition of groups for RP-to-group mapping.";
  }
  grouping vpn-service-multicast {
   container multicast {
    if-feature multicast;
    leaf enabled {
     type boolean;
     default false;
     description
      "Enables multicast.";
    }
    container customer-tree-flavors {
     leaf-list tree-flavor {
       type identityref {
        base multicast-tree-type;
       }
       description
        "Type of tree to be used.";
     }
     description
      "Type of trees used by customer.";
    }

Litkowski, et al. Standards Track [Page 116] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

    container rp {
     container rp-group-mappings {
      list rp-group-mapping {
       key id;
       leaf id {
        type uint16;
        description
         "Unique identifier for the mapping.";
       }
       container provider-managed {
        leaf enabled {
         type boolean;
         default false;
         description
          "Set to true if the RP must be a provider-managed node.
          Set to false if it is a customer-managed node.";
        }
        leaf rp-redundancy {
         when "../enabled = 'true'" {
          description
           "Relevant when the RP is provider-managed.";
         }
         type boolean;
         default false;
         description
          "If true, a redundancy mechanism for the RP is required.";
        }
        leaf optimal-traffic-delivery {
         when "../enabled = 'true'" {
          description
           "Relevant when the RP is provider-managed.";
         }
         type boolean;
         default false;
         description
          "If true, the SP must ensure that
          traffic uses an optimal path.";
        }
        description
         "Parameters for a provider-managed RP.";
       }

Litkowski, et al. Standards Track [Page 117] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

       leaf rp-address {
        when "../provider-managed/enabled = 'false'" {
         description
          "Relevant when the RP is provider-managed.";
        }
        type inet:ip-address;
        description
         "Defines the address of the RP.
         Used if the RP is customer-managed.";
       }
       container groups {
        list group {
         key id;
         leaf id {
          type uint16;
          description
           "Identifier for the group.";
         }
         uses multicast-rp-group-cfg;
         description
          "List of groups.";
        }
        description
         "Multicast groups associated with the RP.";
       }
       description
        "List of RP-to-group mappings.";
      }
      description
       "RP-to-group mappings.";
     }
     container rp-discovery {
      leaf rp-discovery-type {
       type identityref {
        base multicast-rp-discovery-type;
       }
       default static-rp;
       description
        "Type of RP discovery used.";
      }

Litkowski, et al. Standards Track [Page 118] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

      container bsr-candidates {
       when "../rp-discovery-type = 'bsr-rp'" {
        description
         "Only applicable if discovery type is BSR-RP.";
       }
       leaf-list bsr-candidate-address {
        type inet:ip-address;
        description
         "Address of BSR candidate.";
       }
       description
        "Customer BSR candidate's address.";
      }
      description
       "RP discovery parameters.";
     }
     description
      "RP parameters.";
    }
    description
     "Multicast global parameters for the VPN service.";
   }
   description
    "Grouping for multicast VPN definition.";
  }
  grouping vpn-service-mpls {
   leaf carrierscarrier {
    if-feature carrierscarrier;
    type boolean;
    default false;
    description
     "The VPN is using CsC, and so MPLS is required.";
   }
   description
    "Grouping for MPLS CsC definition.";
  }

Litkowski, et al. Standards Track [Page 119] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

  grouping customer-location-info {
   container locations {
    list location {
     key location-id;
     leaf location-id {
      type svc-id;
      description
       "Identifier for a particular location.";
     }
     leaf address {
      type string;
      description
       "Address (number and street) of the site.";
     }
     leaf postal-code {
      type string;
      description
       "Postal code of the site.";
     }
     leaf state {
      type string;
      description
       "State of the site.  This leaf can also be used to describe
       a region for a country that does not have states.";
     }
     leaf city {
      type string;
      description
       "City of the site.";
     }
     leaf country-code {
      type string {
       pattern '[A-Z]{2}';
      }
      description
       "Country of the site.
       Expressed as ISO ALPHA-2 code.";
     }
     description
      "Location of the site.";
     }
     description
      "List of locations for the site.";
   }
   description
    "This grouping defines customer location parameters.";
  }

Litkowski, et al. Standards Track [Page 120] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

  grouping site-group {
   container groups {
    list group {
     key group-id;
     leaf group-id {
      type string;
      description
       "Group-id the site belongs to.";
     }
     description
      "List of group-ids.";
    }
    description
     "Groups the site or site-network-access belongs to.";
   }
   description
    "Grouping definition to assign
    group-ids to site or site-network-access.";
  }
  grouping site-diversity {
   container site-diversity {
     if-feature site-diversity;
     uses site-group;
     description
      "Diversity constraint type.
      All site-network-accesses will inherit the group values
      defined here.";
    }
   description
    "This grouping defines site diversity parameters.";
  }
  grouping access-diversity {
   container access-diversity {
     if-feature site-diversity;
     uses site-group;

Litkowski, et al. Standards Track [Page 121] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

     container constraints {
      list constraint {
       key constraint-type;
       leaf constraint-type {
        type identityref {
         base placement-diversity;
        }
        description
         "Diversity constraint type.";
       }
       container target {
        choice target-flavor {
         case id {
          list group {
           key group-id;
           leaf group-id {
            type string;
            description
             "The constraint will be applied against
             this particular group-id.";
           }
           description
            "List of groups.";
          }
         }
         case all-accesses {
          leaf all-other-accesses {
           type empty;
           description
            "The constraint will be applied against
            all other site network accesses of this site.";
          }
         }
         case all-groups {
          leaf all-other-groups {
           type empty;
           description
            "The constraint will be applied against
            all other groups managed by the customer.";
          }
         }
         description
          "Choice for the group definition.";
        }

Litkowski, et al. Standards Track [Page 122] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

        description
         "The constraint will be applied against
         this list of groups.";
       }
       description
        "List of constraints.";
      }
      description
       "Placement constraints for this site network access.";
     }
     description
      "Diversity parameters.";
    }
   description
    "This grouping defines access diversity parameters.";
  }
  grouping operational-requirements {
     leaf requested-site-start {
       type yang:date-and-time;
       description
        "Optional leaf indicating requested date and time when the
        service at a particular site is expected to start.";
      }
      leaf requested-site-stop {
       type yang:date-and-time;
       description
        "Optional leaf indicating requested date and time when the
        service at a particular site is expected to stop.";
      }
   description
    "This grouping defines some operational parameters.";
  }

Litkowski, et al. Standards Track [Page 123] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

  grouping operational-requirements-ops {
      leaf actual-site-start {
       type yang:date-and-time;
       config false;
       description
        "Optional leaf indicating actual date and time when the
        service at a particular site actually started.";
      }
      leaf actual-site-stop {
       type yang:date-and-time;
       config false;
       description
        "Optional leaf indicating actual date and time when the
        service at a particular site actually stopped.";
      }
   description
    "This grouping defines some operational parameters.";
  }
  grouping flow-definition {
   container match-flow {
    leaf dscp {
     type inet:dscp;
     description
      "DSCP value.";
    }
    leaf dot1p {
     type uint8 {
      range "0..7";
     }
     description
      "802.1p matching.";
    }
    leaf ipv4-src-prefix {
     type inet:ipv4-prefix;
     description
      "Match on IPv4 src address.";
    }
    leaf ipv6-src-prefix {
     type inet:ipv6-prefix;
     description
      "Match on IPv6 src address.";
    }
    leaf ipv4-dst-prefix {
     type inet:ipv4-prefix;
     description
      "Match on IPv4 dst address.";
    }

Litkowski, et al. Standards Track [Page 124] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

    leaf ipv6-dst-prefix {
     type inet:ipv6-prefix;
     description
      "Match on IPv6 dst address.";
    }
    leaf l4-src-port {
     type inet:port-number;
     description
      "Match on Layer 4 src port.";
    }
    leaf-list target-sites {
     type svc-id;
     description
      "Identify a site as traffic destination.";
    }
    container l4-src-port-range {
     leaf lower-port {
      type inet:port-number;
      description
       "Lower boundary for port.";
     }
     leaf upper-port {
      type inet:port-number;
      must ". >= ../lower-port" {
       description
        "Upper boundary must be higher than lower boundary.";
      }
      description
       "Upper boundary for port.";
     }
     description
      "Match on Layer 4 src port range.";
    }
    leaf l4-dst-port {
     type inet:port-number;
     description
      "Match on Layer 4 dst port.";
    }
    container l4-dst-port-range {
     leaf lower-port {
      type inet:port-number;
      description
       "Lower boundary for port.";
     }

Litkowski, et al. Standards Track [Page 125] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

     leaf upper-port {
      type inet:port-number;
      must ". >= ../lower-port" {
       description
        "Upper boundary must be higher than lower boundary.";
      }
      description
       "Upper boundary for port.";
     }
     description
      "Match on Layer 4 dst port range.";
    }
    leaf protocol-field {
     type union {
      type uint8;
      type identityref {
       base protocol-type;
      }
     }
     description
      "Match on IPv4 protocol or IPv6 Next Header field.";
    }
    description
     "Describes flow-matching criteria.";
   }
   description
    "Flow definition based on criteria.";
  }
  grouping site-service-basic {
   leaf svc-input-bandwidth {
       type uint32;
       units bps;
       description
        "From the PE's perspective, the service input
        bandwidth of the connection.";
   }
   leaf svc-output-bandwidth {
      type uint32;
      units bps;
      description
       "From the PE's perspective, the service output
       bandwidth of the connection.";
   }

Litkowski, et al. Standards Track [Page 126] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

   leaf svc-mtu {
    type uint16;
    units bytes;
    description
     "MTU at service level.  If the service is IP,
     it refers to the IP MTU.";
   }
   description
    "Defines basic service parameters for a site.";
  }
  grouping site-protection {
   container traffic-protection {
    if-feature fast-reroute;
    leaf enabled {
     type boolean;
     default false;
     description
      "Enables traffic protection of access link.";
    }
    description
     "Fast Reroute service parameters for the site.";
   }
   description
    "Defines protection service parameters for a site.";
  }
  grouping site-service-mpls {
   container carrierscarrier {
    if-feature carrierscarrier;
    leaf signalling-type {
     type enumeration {
      enum "ldp" {
       description
        "Use LDP as the signalling protocol
        between the PE and the CE.";
      }
      enum "bgp" {
       description
        "Use BGP (as per RFC 3107) as the signalling protocol
        between the PE and the CE.
        In this case, BGP must also be configured as
        the routing protocol.";
      }
     }
     description
      "MPLS signalling type.";
    }

Litkowski, et al. Standards Track [Page 127] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

    description
     "This container is used when the customer provides
     MPLS-based services.  This is used in the case of CsC.";
   }
   description
    "Defines MPLS service parameters for a site.";
  }
  grouping site-service-qos-profile {
   container qos {
    if-feature qos;
    container qos-classification-policy {
     list rule {
      key id;
      ordered-by user;
      leaf id {
       type uint16;
       description
        "ID of the rule.";
      }
      choice match-type {
       case match-flow {
        uses flow-definition;
       }
       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 class of service.
        This identifier is internal to the administration.";
      }
      description
       "List of marking rules.";
     }

Litkowski, et al. Standards Track [Page 128] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

     description
      "Configuration of the traffic classification policy.";
    }
    container qos-profile {
     choice qos-profile {
      description
       "Choice for QoS profile.
       Can be standard profile or custom.";
      case standard {
       leaf profile {
        type string;
        description
         "QoS profile to be used.";
       }
      }
      case custom {
       container classes {
        if-feature qos-custom;
        list class {
         key class-id;
         leaf class-id {
          type string;
          description
           "Identification of the class of service.
           This identifier is internal to the administration.";
         }
         leaf rate-limit {
          type uint8;
          units percent;
          description
           "To be used if the class must be rate-limited.
           Expressed as percentage of the service bandwidth.";
         }
         container latency {
          choice flavor {
           case lowest {
            leaf use-lowest-latency {
             type empty;
             description
              "The traffic class should use the path with the
              lowest latency.";
            }
           }

Litkowski, et al. Standards Track [Page 129] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

           case boundary {
            leaf latency-boundary {
             type uint16;
             units msec;
             description
              "The traffic class should use a path with a
              defined maximum latency.";
            }
           }
           description
            "Latency constraint on the traffic class.";
          }
          description
           "Latency constraint on the traffic class.";
         }
         container 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 latency-boundary {
             type uint32;
             units usec;
             description
              "The traffic class should use a path with a
              defined maximum jitter.";
            }
           }
           description
            "Jitter constraint on the traffic class.";
          }
          description
           "Jitter constraint on the traffic class.";
         }
         container bandwidth {
          leaf guaranteed-bw-percent {
           type uint8;
           units percent;
           description
            "To be used to define the guaranteed bandwidth
            as a percentage of the available service bandwidth.";
          }

Litkowski, et al. Standards Track [Page 130] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

          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 classes of services.";
        }
        description
         "Container for list of classes of services.";
       }
      }
     }
     description
      "QoS profile configuration.";
    }
    description
     "QoS configuration.";
   }
   description
    "This grouping defines QoS parameters for a site.";
  }
  grouping site-security-authentication {
   container authentication {
    description
     "Authentication parameters.";
   }
   description
    "This grouping defines authentication parameters for a site.";
  }
  grouping site-security-encryption {
   container encryption {
    if-feature encryption;
    leaf enabled {
     type boolean;
     default false;
     description
      "If true, access encryption is required.";
    }

Litkowski, et al. Standards Track [Page 131] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

    leaf layer {
     type enumeration {
      enum layer2 {
       description
        "Encryption will occur at Layer 2.";
      }
      enum layer3 {
       description
        "Encryption will occur at Layer 3.
        For example, IPsec may be used.";
      }
     }
     mandatory true;
     description
      "Layer on which encryption is applied.";
    }
    container encryption-profile {
     choice profile {
      case provider-profile {
       leaf profile-name {
        type string;
        description
         "Name of the SP profile to be applied.";
       }
      }
      case customer-profile {
       leaf algorithm {
        type string;
        description
         "Encryption algorithm to be used.";
       }
       choice key-type {
        case psk {
         leaf preshared-key {
          type string;
          description
           "Key coming from customer.";
         }
        }
        case pki {
        }
        description
         "Type of keys to be used.";
       }
      }

Litkowski, et al. Standards Track [Page 132] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

      description
       "Choice of profile.";
     }
     description
      "Profile of encryption to be applied.";
    }
    description
     "Encryption parameters.";
   }
   description
    "This grouping defines encryption parameters for a site.";
  }
  grouping site-attachment-bearer {
   container bearer {
    container requested-type {
     if-feature requested-type;
     leaf requested-type {
      type string;
      description
       "Type of requested bearer: Ethernet, DSL,
       Wireless, etc.  Operator specific.";
     }
     leaf strict {
      type boolean;
      default false;
      description
       "Defines whether requested-type is a preference
       or a strict requirement.";
     }
     description
      "Container for requested-type.";
    }
    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 access type.";
    }
    leaf bearer-reference {
     if-feature bearer-reference;
     type string;
     description
      "This is an internal reference for the SP.";
    }

Litkowski, et al. Standards Track [Page 133] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

    description
     "Bearer-specific parameters.
     To be augmented.";
   }
   description
    "Defines physical properties of a site attachment.";
  }
  grouping site-routing {
   container routing-protocols {
    list routing-protocol {
     key type;
     leaf type {
      type identityref {
       base routing-protocol-type;
      }
      description
       "Type of routing protocol.";
     }
     container ospf {
      when "../type = 'ospf'" {
       description
        "Only applies when protocol is OSPF.";
      }
      if-feature rtg-ospf;
      leaf-list address-family {
       type address-family;
       description
        "Address family to be activated.";
      }
      leaf area-address {
       type yang:dotted-quad;
       description
        "Area address.";
      }
      leaf metric {
       type uint16;
       description
        "Metric of the PE-CE link.";
      }

Litkowski, et al. Standards Track [Page 134] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

      container sham-links {
       if-feature rtg-ospf-sham-link;
       list sham-link {
        key target-site;
        leaf target-site {
         type svc-id;
         description
          "Target site for the sham link connection.
          The site is referred to by its ID.";
        }
        leaf metric {
         type uint16;
         description
          "Metric of the sham link.";
        }
        description
         "Creates a sham link with another site.";
       }
       description
        "List of sham links.";
      }
      description
       "OSPF-specific configuration.";
     }
     container bgp {
      when "../type = 'bgp'" {
       description
        "Only applies when protocol is BGP.";
      }
      if-feature rtg-bgp;
      leaf autonomous-system {
       type uint32;
       description
        "AS number.";
      }
      leaf-list address-family {
       type address-family;
       description
        "Address family to be activated.";
      }
      description
       "BGP-specific configuration.";
     }

Litkowski, et al. Standards Track [Page 135] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

     container static {
      when "../type = 'static'" {
       description
        "Only applies when protocol is static.";
      }
      container cascaded-lan-prefixes {
       list ipv4-lan-prefixes {
        if-feature ipv4;
        key "lan next-hop";
        leaf lan {
         type inet:ipv4-prefix;
         description
          "LAN prefixes.";
        }
        leaf lan-tag {
         type string;
         description
          "Internal tag to be used in VPN policies.";
        }
        leaf next-hop {
         type inet:ipv4-address;
         description
          "Next-hop address to use on the customer side.";
        }
        description
         "List of LAN prefixes for the site.";
       }
       list ipv6-lan-prefixes {
        if-feature ipv6;
        key "lan next-hop";
        leaf lan {
         type inet:ipv6-prefix;
         description
          "LAN prefixes.";
        }
        leaf lan-tag {
         type string;
         description
          "Internal tag to be used in VPN policies.";
        }
        leaf next-hop {
         type inet:ipv6-address;
         description
          "Next-hop address to use on the customer side.";
        }

Litkowski, et al. Standards Track [Page 136] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

        description
         "List of LAN prefixes for the site.";
       }
       description
        "LAN prefixes from the customer.";
      }
      description
       "Configuration specific to static routing.";
     }
     container rip {
      when "../type = 'rip'" {
       description
        "Only applies when protocol is RIP.";
      }
      if-feature rtg-rip;
      leaf-list address-family {
       type address-family;
       description
        "Address family to be activated.";
      }
      description
       "Configuration specific to RIP routing.";
     }
     container vrrp {
      when "../type = 'vrrp'" {
       description
        "Only applies when protocol is VRRP.";
      }
      if-feature rtg-vrrp;
      leaf-list address-family {
       type address-family;
       description
        "Address family to be activated.";
      }
      description
       "Configuration specific to VRRP routing.";
     }
     description
      "List of routing protocols used on
      the site.  This list can be augmented.";
    }

Litkowski, et al. Standards Track [Page 137] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

    description
     "Defines routing protocols.";
   }
   description
    "Grouping for routing protocols.";
  }
  grouping site-attachment-ip-connection {
   container ip-connection {
    container ipv4 {
     if-feature ipv4;
     leaf address-allocation-type {
      type identityref {
       base address-allocation-type;
      }
      default "static-address";
      description
       "Defines how addresses are allocated.";
     }
     leaf number-of-dynamic-address {
      when "../address-allocation-type = 'provider-dhcp'" {
       description
        "Only applies when addresses are allocated by DHCP.";
      }
      type uint8;
      default 1;
      description
       "Describes the number of IP addresses the customer requires.";
     }
     container dhcp-relay {
      when "../address-allocation-type = 'provider-dhcp-relay'" {
       description
        "Only applies when provider is required to implement
        DHCP relay function.";
      }
      container customer-dhcp-servers {
       leaf-list server-ip-address {
        type inet:ipv4-address;
        description
         "IP address of customer DHCP server.";
       }
       description
        "Container for list of customer DHCP servers.";
      }
      description
       "DHCP relay provided by operator.";
     }

Litkowski, et al. Standards Track [Page 138] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

     container addresses {
      when "../address-allocation-type = 'static-address'" {
       description
        "Only applies when protocol allocation type is static.";
      }
      leaf provider-address {
       type inet:ipv4-address;
       description
        "Address of provider side.";
      }
      leaf customer-address {
       type inet:ipv4-address;
       description
        "Address of customer side.";
      }
      leaf mask {
       type uint8 {
        range "0..31";
       }
       description
        "Subnet mask expressed in bits.";
      }
      description
       "Describes IP addresses used.";
     }
     description
      "IPv4-specific parameters.";
    }
    container ipv6 {
     if-feature ipv6;
     leaf address-allocation-type {
      type identityref {
       base address-allocation-type;
      }
      default "static-address";
      description
       "Defines how addresses are allocated.";
     }
     leaf number-of-dynamic-address {
      when
      "../address-allocation-type = 'provider-dhcp' "+
      "or ../address-allocation-type "+
      "= 'provider-dhcp-slaac'" {
       description
        "Only applies when addresses are allocated by DHCP.";
      }

Litkowski, et al. Standards Track [Page 139] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

      type uint8;
      default 1;
      description
       "Describes the number of IP addresses the customer requires.";
     }
     container dhcp-relay {
      when "../address-allocation-type = 'provider-dhcp-relay'" {
       description
        "Only applies when provider is required to implement
        DHCP relay function.";
      }
      container customer-dhcp-servers {
       leaf-list server-ip-address {
        type inet:ipv6-address;
        description
         "IP address of customer DHCP server.";
       }
       description
        "Container for list of customer DHCP servers.";
      }
      description
       "DHCP relay provided by operator.";
     }
     container addresses {
      when "../address-allocation-type = 'static-address'" {
       description
        "Only applies when protocol allocation type is static.";
      }
      leaf provider-address {
       type inet:ipv6-address;
       description
        "Address of provider side.";
      }
      leaf customer-address {
       type inet:ipv6-address;
       description
        "Address of customer side.";
      }
      leaf mask {
       type uint8 {
        range "0..127";
       }
       description
        "Subnet mask expressed in bits.";
      }
      description
       "Describes IP addresses used.";
     }

Litkowski, et al. Standards Track [Page 140] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

     description
      "IPv6-specific parameters.";
    }
    container oam {
     container bfd {
      if-feature bfd;
      leaf enabled {
       type boolean;
       default false;
       description
        "BFD activation.";
      }
      choice holdtime {
       case profile {
        leaf profile-name {
         type string;
         description
          "Well-known SP profile.";
        }
        description
         "Well-known SP profile.";
       }
       case fixed {
        leaf fixed-value {
         type uint32;
         units msec;
         description
          "Expected holdtime expressed in msec.";
        }
       }
       description
        "Choice for holdtime flavor.";
      }
      description
       "Container for BFD.";
     }
     description
      "Defines the OAM mechanisms used on the connection.";
    }
    description
     "Defines connection parameters.";
   }
   description
    "This grouping defines IP connection parameters.";
  }

Litkowski, et al. Standards Track [Page 141] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

  grouping site-service-multicast {
   container multicast {
    if-feature multicast;
    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.";
    }
    container multicast-address-family {
     leaf ipv4 {
      if-feature ipv4;
      type boolean;
      default true;
      description
       "Enables IPv4 multicast.";
     }
     leaf ipv6 {
      if-feature ipv6;
      type boolean;
      default false;
      description
       "Enables IPv6 multicast.";
     }
     description
      "Defines protocol to carry multicast.";
    }
    leaf protocol-type {
     type enumeration {
      enum host {
       description
        "Hosts are directly connected to the provider network.
        Host protocols such as IGMP or MLD are required.";
      }

Litkowski, et al. Standards Track [Page 142] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

      enum router {
       description
        "Hosts are behind a customer router.
        PIM will be implemented.";
      }
      enum both {
       description
        "Some hosts are behind a customer router, and some others
        are directly connected to the provider network.
        Both host and routing protocols must be used.
        Typically, IGMP and PIM will be implemented.";
      }
     }
     default "both";
     description
      "Multicast protocol type to be used with the customer site.";
    }
    description
     "Multicast parameters for the site.";
   }
   description
    "Multicast parameters for the site.";
  }
  grouping site-management {
   container management {
    leaf type {
     type identityref {
      base management;
     }
     description
      "Management type of the connection.";
    }
    description
     "Management configuration.";
   }
   description
    "Management parameters for the site.";
  }

Litkowski, et al. Standards Track [Page 143] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

  grouping site-devices {
   container devices {
    must "/l3vpn-svc/sites/site/management/type = "+
     "'provider-managed' or "+
     "/l3vpn-svc/sites/site/management/type = "+
     "'co-managed'" {
      description
       "Applicable only for provider-managed or co-managed device.";
     }
    list device {
     key device-id;
     leaf device-id {
      type svc-id;
      description
       "Identifier for the device.";
     }
     leaf location {
      type leafref {
       path "/l3vpn-svc/sites/site/locations/"+
        "location/location-id";
      }
      description
       "Location of the device.";
     }
     container management {
      must "/l3vpn-svc/sites/site/management/type"+
       "= 'co-managed'" {
        description
         "Applicable only for co-managed device.";
       }
      leaf address-family {
       type address-family;
       description
        "Address family used for management.";
      }
      leaf address {
       type inet:ip-address;
       description
        "Management address.";
      }
      description
       "Management configuration.  Applicable only for
       co-managed device.";
     }

Litkowski, et al. Standards Track [Page 144] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

     description
      "Device configuration.";
    }
    description
     "List of devices requested by customer.";
   }
   description
    "Grouping for device allocation.";
  }
  grouping site-vpn-flavor {
   leaf site-vpn-flavor {
    type identityref {
     base site-vpn-flavor;
    }
    default site-vpn-flavor-single;
    description
     "Defines whether the site is, for example,
     a single VPN site or a multiVPN.";
   }
   description
    "Grouping for site VPN flavor.";
  }
  grouping site-vpn-policy {
   container vpn-policies {
    list vpn-policy {
     key vpn-policy-id;
     leaf vpn-policy-id {
      type svc-id;
      description
       "Unique identifier for the VPN policy.";
     }
     list entries {
      key id;
      leaf id {
        type svc-id;
        description
         "Unique identifier for the policy entry.";
      }

Litkowski, et al. Standards Track [Page 145] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

      container filter {
       choice lan {
        case prefixes {
         leaf-list ipv4-lan-prefix {
          if-feature ipv4;
          type inet:ipv4-prefix;
          description
           "List of IPv4 prefixes to be matched.";
         }
         leaf-list ipv6-lan-prefix {
          if-feature ipv6;
          type inet:ipv6-prefix;
          description
           "List of IPv6 prefixes to be matched.";
         }
        }
        case lan-tag {
         leaf-list lan-tag {
          type string;
          description
           "List of 'lan-tag' items to be matched.";
         }
        }
        description
         "Choice of ways to do LAN matching.";
       }
       description
        "If used, it permits the splitting of
        site LANs among multiple VPNs.
        If no filter is used, all the LANs will be
        part of the same VPNs with the same role.";
      }
      container vpn {
       leaf vpn-id {
        type leafref {
         path "/l3vpn-svc/vpn-services/"+
         "vpn-service/vpn-id";
        }
        mandatory true;
        description
         "Reference to an IP VPN.";
       }

Litkowski, et al. Standards Track [Page 146] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

       leaf site-role {
        type identityref {
         base site-role;
        }
        default any-to-any-role;
        description
         "Role of the site in the IP VPN.";
       }
       description
        "List of VPNs the LAN is associated with.";
      }
      description
       "List of entries for export policy.";
     }
     description
      "List of VPN policies.";
    }
    description
     "VPN policy.";
   }
   description
    "VPN policy parameters for the site.";
  }
  grouping site-maximum-routes {
   container maximum-routes {
    list address-family {
     key af;
     leaf af {
      type address-family;
      description
       "Address family.";
     }
     leaf maximum-routes {
      type uint32;
      description
       "Maximum prefixes the VRF can accept for this address family.";
     }
     description
      "List of address families.";
    }
    description
     "Defines 'maximum-routes' for the VRF.";
   }

Litkowski, et al. Standards Track [Page 147] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

   description
    "Defines 'maximum-routes' for the site.";
  }
  grouping site-security {
   container security {
    uses site-security-authentication;
    uses site-security-encryption;
    description
     "Site-specific security parameters.";
   }
   description
    "Grouping for security parameters.";
  }
  grouping site-service {
   container service {
    uses site-service-qos-profile;
    uses site-service-mpls;
    uses site-service-multicast;
    description
     "Service parameters on the attachment.";
   }
   description
    "Grouping for service parameters.";
  }
  grouping site-network-access-service {
   container service {
    uses site-service-basic;
    uses site-service-qos-profile;
    uses site-service-mpls;
    uses site-service-multicast;
    description
     "Service parameters on the attachment.";
   }
   description
    "Grouping for service parameters.";
  }

Litkowski, et al. Standards Track [Page 148] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

  grouping vpn-extranet {
   container extranet-vpns {
    if-feature extranet-vpn;
    list extranet-vpn {
     key vpn-id;
     leaf vpn-id {
      type svc-id;
      description
       "Identifies the target VPN.";
     }
     leaf local-sites-role {
      type identityref {
       base site-role;
      }
      default any-to-any-role;
      description
       "This describes the role of the
       local sites in the target VPN topology.";
     }
     description
      "List of extranet VPNs the local VPN is attached to.";
    }
    description
     "Container for extranet VPN configuration.";
   }
   description
    "Grouping for extranet VPN configuration.
    This provides an easy way to interconnect
    all sites from two VPNs.";
  }
  grouping site-attachment-availability {
   container availability {
    leaf access-priority {
     type uint32;
     default 1;
     description
      "Defines the priority for the access.
      The higher the access-priority value,
      the higher the preference of the access will be.";
    }
    description
     "Availability parameters (used for multihoming).";
   }

Litkowski, et al. Standards Track [Page 149] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

   description
    "Defines availability parameters for a site.";
  }
  grouping access-vpn-policy {
   container vpn-attachment {
    choice attachment-flavor {
     case vpn-policy-id {
      leaf vpn-policy-id {
       type leafref {
        path "/l3vpn-svc/sites/site/"+
        "vpn-policies/vpn-policy/"+
        "vpn-policy-id";
       }
       description
        "Reference to a VPN policy.";
      }
     }
     case vpn-id {
      leaf vpn-id {
       type leafref {
        path "/l3vpn-svc/vpn-services"+
        "/vpn-service/vpn-id";
       }
       description
        "Reference to a VPN.";
      }
      leaf site-role {
       type identityref {
         base site-role;
        }
       default any-to-any-role;
       description
        "Role of the site in the IP VPN.";
      }
     }
     mandatory true;
     description
      "Choice for VPN attachment flavor.";
    }
    description
     "Defines VPN attachment of a site.";
   }
   description
    "Defines the VPN attachment rules for a site's logical access.";
  }

Litkowski, et al. Standards Track [Page 150] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

  grouping vpn-svc-cfg {
   leaf vpn-id {
     type svc-id;
     description
      "VPN identifier.  Local administration meaning.";
    }
    leaf customer-name {
     type string;
     description
      "Name of the customer.";
    }
   leaf vpn-service-topology {
    type identityref {
     base vpn-topology;
    }
    default "any-to-any";
    description
     "VPN service topology.";
   }
   uses vpn-service-cloud-access;
   uses vpn-service-multicast;
   uses vpn-service-mpls;
   uses vpn-extranet;
   description
    "Grouping for VPN service configuration.";
  }
  grouping site-top-level-cfg {
   uses operational-requirements;
   uses customer-location-info;
   uses site-devices;
   uses site-diversity;
   uses site-management;
   uses site-vpn-policy;
   uses site-vpn-flavor;
   uses site-maximum-routes;
   uses site-security;
   uses site-service;
   uses site-protection;
   uses site-routing;
   description
    "Grouping for site top-level configuration.";
  }

Litkowski, et al. Standards Track [Page 151] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

  grouping site-network-access-top-level-cfg {
   leaf site-network-access-type {
    type identityref {
     base site-network-access-type;
    }
    default "point-to-point";
    description
     "Describes the type of connection, e.g.,
     point-to-point or multipoint.";
   }
   choice location-flavor {
    case location {
     when "/l3vpn-svc/sites/site/management/type = "+
       "'customer-managed'" {
        description
         "Applicable only for customer-managed device.";
      }
     leaf location-reference {
      type leafref {
       path "/l3vpn-svc/sites/site/locations/"+
          "location/location-id";
      }
      description
       "Location of the site-network-access.";
     }
    }
    case device {
     when "/l3vpn-svc/sites/site/management/type = "+
       "'provider-managed' or "+
       "/l3vpn-svc/sites/site/management/type = "+
       "'co-managed'" {
        description
         "Applicable only for provider-managed or co-managed device.";
      }
     leaf device-reference {
      type leafref {
       path "/l3vpn-svc/sites/site/devices/"+
          "device/device-id";
      }
      description
       "Identifier of CE to use.";
     }
    }
    mandatory true;
    description
     "Choice of how to describe the site's location.";
   }

Litkowski, et al. Standards Track [Page 152] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

   uses access-diversity;
   uses site-attachment-bearer;
   uses site-attachment-ip-connection;
   uses site-security;
   uses site-network-access-service;
   uses site-routing;
   uses site-attachment-availability;
   uses access-vpn-policy;
   description
    "Grouping for site network access top-level configuration.";
  }
  /* Main blocks */
  container l3vpn-svc {
   container vpn-services {
    list vpn-service {
     key vpn-id;
     uses vpn-svc-cfg;
     description
      "List of VPN services.";
    }
    description
     "Top-level container for the VPN services.";
   }
   container sites {
    list site {
     key site-id;
     leaf site-id {
      type svc-id;
      description
       "Identifier of the site.";
     }
     uses site-top-level-cfg;
     uses operational-requirements-ops;

Litkowski, et al. Standards Track [Page 153] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

     container site-network-accesses {
      list site-network-access {
       key site-network-access-id;
       leaf site-network-access-id {
        type svc-id;
        description
         "Identifier for the access.";
       }
       uses site-network-access-top-level-cfg;
       description
        "List of accesses for a site.";
      }
      description
       "List of accesses for a site.";
     }
     description
      "List of sites.";
    }
    description
     "Container for sites.";
   }
   description
    "Main container for L3VPN service configuration.";
  }
 }
 <CODE ENDS>

10. Security Considerations

 The YANG module defined in this document MAY be accessed via the
 RESTCONF protocol [RFC8040] or the NETCONF protocol [RFC6241].  The
 lowest RESTCONF or NETCONF layer requires that the transport-layer
 protocol provide both data integrity and confidentiality; see
 Section 2 in [RFC8040] and Section 2 in [RFC6241].  The client MUST
 carefully examine the certificate presented by the server to
 determine if it meets the client's expectations, and the server MUST
 authenticate client access to any protected resource.  The client
 identity derived from the authentication mechanism used is subject to
 the NETCONF Access Control Model (NACM) [RFC6536].  Other protocols
 that are used to access this YANG module are also required to support
 similar security mechanisms.

Litkowski, et al. Standards Track [Page 154] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 The data nodes defined in the "ietf-l3vpn-svc" YANG module MUST be
 carefully created, read, updated, or deleted as appropriate.  The
 entries in the lists below include customer-proprietary or
 confidential information; therefore, access to confidential
 information MUST be limited to authorized clients, and other clients
 MUST NOT be permitted to access the information.
 o  /l3vpn-svc/vpn-services/vpn-service
 o  /l3vpn-svc/sites/site
 The data model proposes some security parameters than can be extended
 via augmentation as part of the customer service request; those
 parameters are described in Section 6.9.

11. IANA Considerations

 IANA has assigned a new URI from the "IETF XML Registry" [RFC3688].
    URI: urn:ietf:params:xml:ns:yang:ietf-l3vpn-svc
    Registrant Contact: The IESG
    XML: N/A; the requested URI is an XML namespace.
 This document adds a new YANG module name in the "YANG Module Names"
 registry [RFC6020]:
    Name: ietf-l3vpn-svc
    Namespace: urn:ietf:params:xml:ns:yang:ietf-l3vpn-svc
    Prefix: l3vpn-svc
    Reference: RFC 8049

12. References

12.1. 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,
            <http://www.rfc-editor.org/info/rfc2119>.
 [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
            DOI 10.17487/RFC3688, January 2004,
            <http://www.rfc-editor.org/info/rfc3688>.
 [RFC4026]  Andersson, L. and T. Madsen, "Provider Provisioned Virtual
            Private Network (VPN) Terminology", RFC 4026,
            DOI 10.17487/RFC4026, March 2005,
            <http://www.rfc-editor.org/info/rfc4026>.

Litkowski, et al. Standards Track [Page 155] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

 [RFC4364]  Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
            Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364,
            February 2006, <http://www.rfc-editor.org/info/rfc4364>.
 [RFC4577]  Rosen, E., Psenak, P., and P. Pillay-Esnault, "OSPF as the
            Provider/Customer Edge Protocol for BGP/MPLS IP Virtual
            Private Networks (VPNs)", RFC 4577, DOI 10.17487/RFC4577,
            June 2006, <http://www.rfc-editor.org/info/rfc4577>.
 [RFC4862]  Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
            Address Autoconfiguration", RFC 4862,
            DOI 10.17487/RFC4862, September 2007,
            <http://www.rfc-editor.org/info/rfc4862>.
 [RFC6020]  Bjorklund, M., Ed., "YANG - A Data Modeling Language for
            the Network Configuration Protocol (NETCONF)", RFC 6020,
            DOI 10.17487/RFC6020, October 2010,
            <http://www.rfc-editor.org/info/rfc6020>.
 [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
            and A. Bierman, Ed., "Network Configuration Protocol
            (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
            <http://www.rfc-editor.org/info/rfc6241>.
 [RFC6513]  Rosen, E., Ed., and R. Aggarwal, Ed., "Multicast in
            MPLS/BGP IP VPNs", RFC 6513, DOI 10.17487/RFC6513,
            February 2012, <http://www.rfc-editor.org/info/rfc6513>.
 [RFC6536]  Bierman, A. and M. Bjorklund, "Network Configuration
            Protocol (NETCONF) Access Control Model", RFC 6536,
            DOI 10.17487/RFC6536, March 2012,
            <http://www.rfc-editor.org/info/rfc6536>.
 [RFC7950]  Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
            RFC 7950, DOI 10.17487/RFC7950, August 2016,
            <http://www.rfc-editor.org/info/rfc7950>.
 [RFC8040]  Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
            Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
            <http://www.rfc-editor.org/info/rfc8040>.

Litkowski, et al. Standards Track [Page 156] RFC 8049 YANG Data Model for L3VPN Service Delivery February 2017

12.2. Informative References

 [RFC4110]  Callon, R. and M. Suzuki, "A Framework for Layer 3
            Provider-Provisioned Virtual Private Networks (PPVPNs)",
            RFC 4110, DOI 10.17487/RFC4110, July 2005,
            <http://www.rfc-editor.org/info/rfc4110>.
 [RFC4760]  Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
            "Multiprotocol Extensions for BGP-4", RFC 4760,
            DOI 10.17487/RFC4760, January 2007,
            <http://www.rfc-editor.org/info/rfc4760>.

Acknowledgements

 Thanks to Qin Wu, Maxim Klyus, Luis Miguel Contreras, Gregory Mirsky,
 Zitao Wang, Jing Zhao, Kireeti Kompella, Eric Rosen, Aijun Wang,
 Michael Scharf, Xufeng Liu, David Ball, Lucy Yong, Jean-Philippe
 Landry, and Andrew Leu for their contributions to this document.

Contributors

 The authors would like to thank Rob Shakir for his major
 contributions to the initial modeling and use cases.

Authors' Addresses

 Stephane Litkowski
 Orange Business Services
 Email: stephane.litkowski@orange.com
 Luis Tomotaki
 Verizon
 Email: luis.tomotaki@verizon.com
 Kenichi Ogaki
 KDDI Corporation
 Email: ke-oogaki@kddi.com

Litkowski, et al. Standards Track [Page 157]

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