Internet-Draft Common Attachment Circuit YANG May 2024
Boucadair, et al. Expires 15 November 2024 [Page]
Workgroup:
OPSAWG
Internet-Draft:
draft-ietf-opsawg-teas-common-ac-11
Published:
Intended Status:
Standards Track
Expires:
Authors:
M. Boucadair, Ed.
Orange
R. Roberts, Ed.
Juniper
O. G. D. Dios
Telefonica
S. B. Giraldo
Nokia
B. Wu
Huawei Technologies

A Common YANG Data Model for Attachment Circuits

Abstract

The document specifies a common Attachment Circuits (ACs) YANG module, which is designed with the intent to be reusable by other models. For example, this common model can be reused by service models to expose ACs as a service, service models that require binding a service to a set of ACs, network and device models to provision ACs, etc.

Discussion Venues

This note is to be removed before publishing as an RFC.

Discussion of this document takes place on the Operations and Management Area Working Group Working Group mailing list (opsawg@ietf.org), which is archived at https://mailarchive.ietf.org/arch/browse/opsawg/.

Source for this draft and an issue tracker can be found at https://github.com/boucadair/attachment-circuit-model.

Status of This Memo

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

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

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

This Internet-Draft will expire on 15 November 2024.

1. Introduction

Connectivity services are provided by networks to customers via dedicated terminating points (e.g., Service Functions (SFs), Customer Premises Equipment (CPEs), Autonomous System Border Routers (ASBRs), data centers gateways, or Internet Exchange Points). A connectivity service is basically about ensuring data transfer received from (or destined to) a given terminating point to (or from) other terminating points that belong to the same customer/service, an interconnection node, or an ancillary node. A set of objectives for the connectivity service may eventually be negotiated and agreed upon between a customer a network provider. For that data transfer to take place within the provider network, it is assumed that adequate setup is provisioned over the links that connect customer terminating points and a provider network (a Provider Edge (PE), typically) so that data can be successfully exchanged over these links. The required setup is referred to in this document as Attachment Circuits (ACs), while the underlying link is referred to as "bearer".

This document adheres to the definition of an attachment circuit as provided in Section 1.2 of [RFC4364], especially:

  • Routers can be attached to each other, or to end systems, in a variety of different ways: PPP connections, ATM Virtual Circuits (VCs), Frame Relay VCs, ethernet interfaces, Virtual Local Area Networks (VLANs) on ethernet interfaces, GRE tunnels, Layer 2 Tunneling Protocol (L2TP) tunnels, IPsec tunnels, etc. We will use the term "attachment circuit" to refer generally to some such means of attaching to a router. An attachment circuit may be the sort of connection that is usually thought of as a "data link", or it may be a tunnel of some sort; what matters is that it be possible for two devices to be network layer peers over the attachment circuit.

When a customer requests a new value-added service, the service can be bound to existing attachment circuits or trigger the instantiation of new attachment circuits. Whether these attachment circuits are specific to a given service or be shared to deliver a variety of services is deployment-specific.

An example of attachment circuits is depicted in Figure 1. A Customer Edge (CE) may be a physical node or a logical entity. A CE is seen by the network as a peer Service Attachment Point (SAP) [RFC9408]. CEs may be dedicated to one single service (e.g., Layer 3 Virtual Private Network (VPN) or Layer 2 VPN) or host multiple services (e.g., Service Functions [RFC7665]). A single AC (as seen by a network provider) may be bound to one or multiple peer SAPs (e.g., "CE#1" and "CE#2"). For example, and as discussed in [RFC4364], multiple CEs can be attached to a PE over the same attachment circuit. This is typically implemented if the Layer 2 infrastructure between the CE and the network provides a multipoint service. The same CE may terminate multiple ACs. These ACs may be over the same or distinct bearers.

AC CE#1 AC CE#3 AC Network CE#2 AC CE#4 AC
Figure 1: Examples of ACs

This document specifies a common module ("ietf-ac-common") for attachment circuits (Section 5). The model is designed with the intent to be reusable by other models and, therefore, ensure consistent AC structures among modules that manipulate ACs. For example, the common model can be reused by service models to expose AC-as-a-Service (ACaaS) (e.g., [I-D.ietf-opsawg-teas-attachment-circuit]), service models that require binding a service to a set of ACs (e.g., Network Slice Service [I-D.ietf-teas-ietf-network-slice-nbi-yang])), network models to provision ACs (e.g., [I-D.ietf-opsawg-ntw-attachment-circuit]), device models, etc.

The common AC module eases data inheritance between modules (e.g., from service to network models as per [RFC8969]).

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

2. Conventions and Definitions

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

LxSM refers to both the Layer 2 Service Model (L2SM) [RFC8466] and the Layer 3 Service Model (L3SM) [RFC8299].

LxNM refers to both the Layer 2 Network Model (L2NM) [RFC9291] and the Layer 3 Network Model (L3NM) [RFC9182].

This document uses the following terms:

Bearer:

A physical or logical link that connects a customer node (or site) to a provider network.

A bearer can be a wireless or wired link. One or multiple technologies can be used to build a bearer. The bearer type can be specified by a customer.

The operator allocates a unique bearer reference to identify a bearer within its network (e.g., customer line identifier). Such a reference can be retrieved by a customer and then used in subsequent service placement requests to unambiguously identify where a service is to be bound.

The concept of bearer can be generalized to refer to the required underlying connection for the provisioning of an attachment circuit.

One or multiple attachment circuits may be hosted over the same bearer (e.g., multiple Virtual Local Area Networks (VLANs) on the same bearer that is provided by a physical link).

Network controller:

Denotes a functional entity responsible for the management of the service provider network. One or multiple network controllers can be deployed in a service provider network.

Service orchestrator:

Refers to a functional entity that interacts with the customer of a network service.

A service orchestrator is typically responsible for the attachment circuits, the Provider Edge (PE) selection, and requesting the activation of the requested services to a network controller.

A service orchestrator may interact with one or more network controllers.

Service provider network:

A network that is able to provide network services (e.g., L2VPN, L3VPN, or Network Slice Services [RFC9543]).

Service provider:

A service provider that offers network services (e.g., L2VPN, L3VPN, or Network Slice Services).

3. Relationship to Other AC Data Models

Figure 2 depicts the relationship between the various AC data models:

ietf-ac-common ietf-ac-svc ietf-bearer-svc ietf-ac-ntw ietf-ac-glue
Figure 2: AC Data Models

"ietf-ac-common" is imported by "ietf-bearer-svc", "ietf-ac-svc", and "ietf-ac-ntw". Bearers managed using "ietf-bearer-svc" may be referenced in the service ACs managed using "ietf-ac-svc". Similarly, a bearer managed using "ietf-bearer-svc" may list the set of ACs that use that bearer. In order to ease correlation between an AC service requests and the actual AC provisioned in the network, "ietf-ac-ntw" uses the AC references exposed by "ietf-ac-svc". To bind Layer 2 VPN or Layer 3 VPN services with ACs, "ietf-ac-glue" augments the LxSM and LxNM with AC service references exposed by "ietf-ac-svc" and AC network references exposed by "ietf-ac-ntw".

4. Description of the AC Common YANG Module

The full tree diagram of the module can be generated using the "pyang" tool [PYANG] with "-f tree --tree-print-groupings" command-line parameters. That tree is not included here because it is too long (Section 3.3 of [RFC8340]). Instead, subtrees are provided for the reader's convenience.

  • The full tree of the "ietf-ac-common" module is available at [AC-Common-Tree].

4.1. Features

The module defines the following features:

'layer2-ac':

Used to indicate support of ACs with Layer 2 properties.

'layer3-ac':

Used to indicate support of ACs with Layer 3 properties.

'server-assigned-reference':

Used to indicate support of server-generated references to access relevant resources.

For example, a bearer request is first created using a name which is assigned by the client, but if this feature is supported, the request will also include a server-generated reference. That reference can be used when requesting the creating of an AC over the existing bearer.

4.2. Identities

The module defines a set of identities, including the following:

'address-allocation-type':

Used to specify the IP address allocation type in an AC. For example, this identity can used to indicate whether the provider network provides DHCP service, DHCP relay, or static addressing. Note that for the IPv6 case, Stateless Address Autoconfiguration (SLAAC) [RFC4862] can be used.

'local-defined-next-hop':

Used to specify next hop actions. For example, this identity can be used to indicate an action to discard traffic for a given destination or treat traffic towards addresses within the specified next-hop prefix as though they are connected to a local link.

'l2-tunnel-type':

Uses to control the Layer 2 tunnel selection for an AC. The current version supports indicating pseudowire, Virtual Private LAN Service (VPLS), and Virtual eXtensible Local Area Network (VXLAN).

'precedence-type':

Used to indicate the redundancy type when requesting ACs. For example, this identity can be used to tag primary and secondary ACs.

'bgp-capability':

Used to indicate a BGP capability [RFC5492]. Examples of BGP capabilities are Multiprotocol extensions for BGP-4 [RFC4760], route refresh [RFC2918], graceful restart [RFC4724], or ADD-PATH [RFC7911].

'role':

Used to indicate the type of an AC: User-to-Network Interface (UNI), Network-to-Network Interface (NNI), or public NNI.

New administrative status types:

In addition to the status types already defined in [RFC9181], this document defines:

  • 'awaiting-validation' to report that a request is pending an adiministrator approval.

  • 'awaiting-processing' to report that a request was approved and validated, but is awaiting more processing before activation.

  • 'admin-prohibited' to report that a request cannot be handled because of administrative policies.

  • 'rejected' to report that a request was rejected reasons not covered by the other status types.

4.3. Reusable Groupings

The module also defines a set of reusable groupings, including the following:

'op-instructions' (Figure 3):

Defines a set of parameters to specify scheduling instructions and report related events for a service request (e.g., AC or bearer).

  grouping service-status:
    +-- status
       +-- admin-status
       |  +-- status?        identityref
       |  +--ro last-change?   yang:date-and-time
       +--ro oper-status
          +--ro status?        identityref
          +--ro last-change?   yang:date-and-time
  grouping op-instructions:
    +-- requested-start?   yang:date-and-time
    +-- requested-stop?    yang:date-and-time
    +--ro actual-start?      yang:date-and-time
    +--ro actual-stop?       yang:date-and-time

Figure 3: Operational Instructions Grouping
Layer 2 encapsulations (Figure 4):

Groupings for the following encapsulation schemes are supported: dot1Q, QinQ, and priority-tagged.

Layer 2 tunnel services (Figure 4):

These groupings are used to define Layer 2 tunnel services that may be needed for the activation of an AC. Examples of supported Layer 2 services are the pseudowire (Section 6.1 of [RFC8077]), VPLS, or VXLAN [RFC7348].

  grouping dot1q:
    +-- tag-type?   identityref
    +-- cvlan-id?   uint16
  grouping priority-tagged:
    +-- tag-type?   identityref
  grouping qinq:
    +-- tag-type?   identityref
    +-- svlan-id?   uint16
    +-- cvlan-id?   uint16
  grouping pseudowire:
    +-- vcid?      uint32
    +-- far-end?   union
  grouping vpls:
    +-- vcid?      uint32
    +-- far-end*   union
  grouping vxlan:
    +-- vni-id?            uint32
    +-- peer-mode?         identityref
    +-- peer-ip-address*   inet:ip-address
  grouping l2-tunnel-service:
    +-- type?         identityref
    +-- pseudowire
    |  +-- vcid?      uint32
    |  +-- far-end?   union
    +-- vpls
    |  +-- vcid?      uint32
    |  +-- far-end*   union
    +-- vxlan
       +-- vni-id?            uint32
       +-- peer-mode?         identityref
       +-- peer-ip-address*   inet:ip-address
Figure 4: Layer 2 Connection Groupings
Layer 3 address allocation (Figure 5):

Defines both IPv4 and IPv6 groupings to specify IP address allocation over an AC. Both dynamic and static address schemes are supported.

IP connections (Figure 5)::

Defines IPv4 and IPv6 groupings for managing Layer 3 connectivity over an AC. Both basic and more elaborated IP connection groupings are supported.

  grouping ipv4-allocation-type:
    +-- prefix-length?             uint8
    +-- address-allocation-type?   identityref
  grouping ipv6-allocation-type:
    +-- prefix-length?             uint8
    +-- address-allocation-type?   identityref
  grouping ipv4-connection-basic:
    +-- prefix-length?                       uint8
    +-- address-allocation-type?             identityref
    +-- (allocation-type)?
       +--:(dynamic)
          +-- (provider-dhcp)?
          |  +--:(dhcp-service-type)
          |     +-- dhcp-service-type?       enumeration
          +-- (dhcp-relay)?
             +--:(customer-dhcp-servers)
                +-- customer-dhcp-servers
                   +-- server-ip-address*   inet:ipv4-address
  grouping ipv6-connection-basic:
    +-- prefix-length?                       uint8
    +-- address-allocation-type?             identityref
    +-- (allocation-type)?
       +--:(dynamic)
          +-- (provider-dhcp)?
          |  +--:(dhcp-service-type)
          |     +-- dhcp-service-type?       enumeration
          +-- (dhcp-relay)?
             +--:(customer-dhcp-servers)
                +-- customer-dhcp-servers
                   +-- server-ip-address*   inet:ipv6-address
  grouping ipv4-connection:
    +-- local-address?                           inet:ipv4-address
    +-- virtual-address?                         inet:ipv4-address
    +-- prefix-length?                           uint8
    +-- address-allocation-type?                 identityref
    +-- (allocation-type)?
       +--:(dynamic)
       |  +-- (address-assign)?
       |  |  +--:(number)
       |  |  |  +-- number-of-dynamic-address?   uint16
       |  |  +--:(explicit)
       |  |     +-- customer-addresses
       |  |        +-- address-pool* [pool-id]
       |  |           +-- pool-id          string
       |  |           +-- start-address    inet:ipv4-address
       |  |           +-- end-address?     inet:ipv4-address
       |  +-- (provider-dhcp)?
       |  |  +--:(dhcp-service-type)
       |  |     +-- dhcp-service-type?           enumeration
       |  +-- (dhcp-relay)?
       |     +--:(customer-dhcp-servers)
       |        +-- customer-dhcp-servers
       |           +-- server-ip-address*   inet:ipv4-address
       +--:(static-addresses)
          +-- address* [address-id]
             +-- address-id          string
             +-- customer-address?   inet:ipv4-address
  grouping ipv6-connection:
    +-- local-address?                           inet:ipv6-address
    +-- virtual-address?                         inet:ipv6-address
    +-- prefix-length?                           uint8
    +-- address-allocation-type?                 identityref
    +-- (allocation-type)?
       +--:(dynamic)
       |  +-- (address-assign)?
       |  |  +--:(number)
       |  |  |  +-- number-of-dynamic-address?   uint16
       |  |  +--:(explicit)
       |  |     +-- customer-addresses
       |  |        +-- address-pool* [pool-id]
       |  |           +-- pool-id          string
       |  |           +-- start-address    inet:ipv6-address
       |  |           +-- end-address?     inet:ipv6-address
       |  +-- (provider-dhcp)?
       |  |  +--:(dhcp-service-type)
       |  |     +-- dhcp-service-type?           enumeration
       |  +-- (dhcp-relay)?
       |     +--:(customer-dhcp-servers)
       |        +-- customer-dhcp-servers
       |           +-- server-ip-address*   inet:ipv6-address
       +--:(static-addresses)
          +-- address* [address-id]
             +-- address-id          string
             +-- customer-address?   inet:ipv6-address
Figure 5: Layer 3 Connection Groupings
Routing parameters & OAM (Figure 6):

In addition to static routing, the module supports the following routing protocols: BGP [RFC4271], OSPF [RFC4577] or [RFC6565], IS-IS [ISO10589][RFC1195][RFC5308], and RIP [RFC2453]. For all supported routing protocols, 'address-family' indicates whether IPv4, IPv6, or both address families are to be activated. For example, this parameter is used to determine whether RIPv2 [RFC2453], RIP Next Generation (RIPng), or both are to be enabled [RFC2080]. More details about supported routing groupings are provided hereafter:

  • Authentication: These groupings include the required information to manage the authentication of OSPF, IS-IS, BGP, and RIP. Similar to [RFC9182], this version of the common AC model assumes that parameters specific to the TCP-AO are preconfigured as part of the key chain that is referenced in the model. No assumption is made about how such a key chain is preconfigured. However, the structure of the key chain should cover data nodes beyond those in [RFC8177], mainly SendID and RecvID (Section 3.1 of [RFC5925]).

  • BGP peer groups: Includes a set of parameters to identify a BGP peer group. Such a group can be defined by providing a local AS Number (ASN), a customer's ASN, and the address families to be activated for this group. BGP peer groups can be identified by a name.

  • Basic parameters: These groupings include the minimal set of routing configuration that is required for the activation of OSPF, IS-IS, BGP, and RIP.

  • Static routing: Parameters to configure an entry of a list of IP static routing entries.

The 'redundancy-group' grouping lists the groups to which an AC belongs [RFC9181]. For example, the 'group-id' is used to associate redundancy or protection constraints of ACs.

 grouping bgp-authentication:
    +-- authentication
       +-- enabled?           boolean
       +-- keying-material
          +-- (option)?
             +--:(ao)
             |  +-- enable-ao?          boolean
             |  +-- ao-keychain?        key-chain:key-chain-ref
             +--:(md5)
             |  +-- md5-keychain?       key-chain:key-chain-ref
             +--:(explicit)
                +-- key-id?             uint32
                +-- key?                string
                +-- crypto-algorithm?   identityref
  grouping ospf-authentication:
    +-- authentication
       +-- enabled?           boolean
       +-- keying-material
          +-- (option)?
             +--:(auth-key-chain)
             |  +-- key-chain?          key-chain:key-chain-ref
             +--:(auth-key-explicit)
                +-- key-id?             uint32
                +-- key?                string
                +-- crypto-algorithm?   identityref
  grouping isis-authentication:
    +-- authentication
       +-- enabled?           boolean
       +-- keying-material
          +-- (option)?
             +--:(auth-key-chain)
             |  +-- key-chain?          key-chain:key-chain-ref
             +--:(auth-key-explicit)
                +-- key-id?             uint32
                +-- key?                string
                +-- crypto-algorithm?   identityref
  grouping rip-authentication:
    +-- authentication
       +-- enabled?           boolean
       +-- keying-material
          +-- (option)?
             +--:(auth-key-chain)
             |  +-- key-chain?          key-chain:key-chain-ref
             +--:(auth-key-explicit)
                +-- key?                string
                +-- crypto-algorithm?   identityref
  grouping bgp-peer-group-without-name:
    +-- local-as?         inet:as-number
    +-- peer-as?          inet:as-number
    +-- address-family?   identityref
  grouping bgp-peer-group-with-name:
    +-- name?             string
    +-- local-as?         inet:as-number
    +-- peer-as?          inet:as-number
    +-- address-family?   identityref
  grouping ospf-basic:
    +-- address-family?   identityref
    +-- area-id           yang:dotted-quad
    +-- metric?           uint16
  grouping isis-basic:
    +-- address-family?   identityref
    +-- area-address      area-address
  grouping ipv4-static-rtg-entry:
    +-- lan?        inet:ipv4-prefix
    +-- lan-tag?    string
    +-- next-hop?   union
    +-- metric?     uint32
  grouping ipv4-static-rtg:
    +-- ipv4-lan-prefixes* [lan next-hop] {vpn-common:ipv4}?
       +-- lan         inet:ipv4-prefix
       +-- lan-tag?    string
       +-- next-hop    union
       +-- metric?     uint32
       +-- status
          +-- admin-status
          |  +-- status?        identityref
          |  +--ro last-change?   yang:date-and-time
          +--ro oper-status
             +--ro status?        identityref
             +--ro last-change?   yang:date-and-time
  grouping ipv6-static-rtg-entry:
    +-- lan?        inet:ipv6-prefix
    +-- lan-tag?    string
    +-- next-hop?   union
    +-- metric?     uint32
  grouping ipv6-static-rtg:
    +-- ipv6-lan-prefixes* [lan next-hop] {vpn-common:ipv6}?
       +-- lan         inet:ipv6-prefix
       +-- lan-tag?    string
       +-- next-hop    union
       +-- metric?     uint32
       +-- status
          +-- admin-status
          |  +-- status?        identityref
          |  +--ro last-change?   yang:date-and-time
          +--ro oper-status
             +--ro status?        identityref
             +--ro last-change?   yang:date-and-time
  grouping bfd:
    +-- holdtime?   uint32
  grouping redundancy-group:
    +-- group* [group-id]
       +-- group-id?     string
       +-- precedence?   identityref
Figure 6: Layer 3 Connection Groupings
Bandwidth parameters (Figure 7):

Bandwidth parameters can be represented using the Committed Information Rate (CIR), the Excess Information Rate (EIR), or the Peak Information Rate (PIR).

These parameters can be provided per bandwidth type. Type values are taken from [RFC9181], e.g.,:

  • 'bw-per-cos':

    The bandwidth is per Class of Service (CoS).

  • 'bw-per-site':

    The bandwidth is to all ACs that belong to the same site.

  grouping bandwidth-parameters:
    +-- cir?   uint64
    +-- cbs?   uint64
    +-- eir?   uint64
    +-- ebs?   uint64
    +-- pir?   uint64
    +-- pbs?   uint64
  grouping bandwidth-per-type:
    +-- bandwidth* [bw-type]
       +-- bw-type      identityref
       +-- (type)?
          +--:(per-cos)
          |  +-- cos* [cos-id]
          |     +-- cos-id    uint8
          |     +-- cir?      uint64
          |     +-- cbs?      uint64
          |     +-- eir?      uint64
          |     +-- ebs?      uint64
          |     +-- pir?      uint64
          |     +-- pbs?      uint64
          +--:(other)
             +-- cir?   uint64
             +-- cbs?   uint64
             +-- eir?   uint64
             +-- ebs?   uint64
             +-- pir?   uint64
             +-- pbs?   uint64
Figure 7: Bandwidth Groupings

5. Common Attachment Circuit YANG Module

This module uses types defined in [RFC6991], [RFC8177], and [RFC9181].

<CODE BEGINS> file "ietf-ac-common@2023-11-13.yang"

module ietf-ac-common {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-ac-common";
  prefix ac-common;

  import ietf-vpn-common {
    prefix vpn-common;
    reference
      "RFC 9181: A Common YANG Data Model for Layer 2 and Layer 3
                 VPNs";
  }
  import ietf-netconf-acm {
    prefix nacm;
    reference
      "RFC 8341: Network Configuration Access Control Model";
  }
  import ietf-inet-types {
    prefix inet;
    reference
      "RFC 6991: Common YANG Data Types, Section 4";
  }
  import ietf-yang-types {
    prefix yang;
    reference
      "RFC 6991: Common YANG Data Types, Section 3";
  }
  import ietf-key-chain {
    prefix key-chain;
    reference
      "RFC 8177: YANG Data Model for Key Chains";
  }

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

     Editor:   Mohamed Boucadair
               <mailto:mohamed.boucadair@orange.com>
     Author:   Richard Roberts
               <mailto:rroberts@juniper.net>
     Author:   Oscar Gonzalez de Dios
               <mailto:oscar.gonzalezdedios@telefonica.com>
     Author:   Samier Barguil
               <mailto:ssamier.barguil_giraldo@nokia.com>
     Author:   Bo Wu
               <mailto:lana.wubo@huawei.com>";
  description
    "This YANG module defines a common attachment circuit (AC)
     YANG model.

     Copyright (c) 2024 IETF Trust and the persons identified as
     authors of the code.  All rights reserved.

     Redistribution and use in source and binary forms, with or
     without modification, is permitted pursuant to, and subject
     to the license terms contained in, the Revised BSD License
     set forth in Section 4.c of the IETF Trust's Legal Provisions
     Relating to IETF Documents
     (https://trustee.ietf.org/license-info).

     This version of this YANG module is part of RFC XXXX; see the
     RFC itself for full legal notices.";

  revision 2023-11-13 {
    description
      "Initial revision.";
    reference
      "RFC XXXX: A Common YANG Data Model for Attachment Circuits";
  }

  /****************************Features************************/

  feature layer2-ac {
    description
      "Indicates support of Layer 2 ACs.";
  }

  feature layer3-ac {
    description
      "Indicates support of Layer 3 ACs.";
  }

  feature server-assigned-reference {
    description
      "This feature indicates support for server-generated references
       and use of such references to access related resources.";
  }

  /****************************Identities************************/
  // IP address allocation types

  identity address-allocation-type {
    description
      "Base identity for address allocation type in the AC.";
  }

  identity provider-dhcp {
    base address-allocation-type;
    description
      "The provider's network provides a DHCP service to the
       customer.";
  }

  identity provider-dhcp-relay {
    base address-allocation-type;
    description
      "The provider's network provides a DHCP relay service to the
       customer.";
  }

  identity provider-dhcp-slaac {
    if-feature "vpn-common:ipv6";
    base address-allocation-type;
    description
      "The provider's network provides a DHCP service to the customer
       as well as IPv6 Stateless Address Autoconfiguration (SLAAC).";
    reference
      "RFC 4862: IPv6 Stateless Address Autoconfiguration";
  }

  identity static-address {
    base address-allocation-type;
    description
      "The provider's network provides static IP addressing to the
       customer.";
  }

  identity slaac {
    if-feature "vpn-common:ipv6";
    base address-allocation-type;
    description
      "The provider's network uses IPv6 SLAAC to provide addressing
       to the customer.";
    reference
      "RFC 4862: IPv6 Stateless Address Autoconfiguration";
  }

  identity dynamic-infra {
    base address-allocation-type;
    description
      "The IP address is dynamically allocated by the hosting
       infrastrcture.";
  }

  // next-hop actions

  identity local-defined-next-hop {
    description
      "Base identity of local defined next hops.";
  }

  identity discard {
    base local-defined-next-hop;
    description
      "Indicates an action to discard traffic for the corresponding
       destination. For example, this can be used to black-hole
       traffic.";
  }

  identity local-link {
    base local-defined-next-hop;
    description
      "Treat traffic towards addresses within the specified next-hop
       prefix as though they are connected to a local link.";
  }

  // Layer 2 tunnel types

  identity l2-tunnel-type {
    description
      "Base identity for Layer 2 tunnel selection for an AC.";
  }

  identity pseudowire {
    base l2-tunnel-type;
    description
      "Pseudowire tunnel termination for the AC.";
  }

  identity vpls {
    base l2-tunnel-type;
    description
      "Virtual Private LAN Service (VPLS) tunnel termination for
       the AC.";
  }

  identity vxlan {
    base l2-tunnel-type;
    description
      "Virtual eXtensible Local Area Network (VXLAN) tunnel
       termination for the AC.";
  }

  // Tagging precedence

  identity precedence-type {
    description
      "Redundancy type. The service can be created with primary and
       secondary tagging.";
  }

  identity primary {
    base precedence-type;
    description
      "Identifies the main attachment circuit.";
  }

  identity secondary {
    base precedence-type;
    description
      "Identifies the secondary attachment circuit.";
  }

 /* BGP Capability Identities. */

  identity bgp-capability {
    description
      "Base identity for a BGP capability.";
    reference
      "RFC 5492: Capabilities Advertisement with BGP-4";
  }

  identity mp-bgp {
    base bgp-capability;
    description
      "Multi-protocol extensions to BGP.";
    reference
      "RFC 4760: Multiprotocol Extentions for BGP-4";
  }

  identity route-refresh {
    base bgp-capability;
    description
      "Route refresh capability.";
    reference
      "RFC 2918: Route Refresh Capability for BGP-4.";
  }

  identity graceful-restart {
    base bgp-capability;
    description
      "Graceful restart capability.";
    reference
      "RFC 4724: Graceful Restart Mechanism for BGP";
  }

  identity add-paths {
    base bgp-capability;
    description
      "A capability that allows the advertisement of multiple
       paths for the same address prefix without the new paths
       implicitly replacing any previous ones.";
    reference
      "RFC 7911: Advertisement of Multiple Paths in BGP";
  }

  // AC Type

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

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

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

  identity public-nni {
    base role;
    description
      "Public peering.";
  }

  // More Admin status types

  identity awaiting-validation {
    base vpn-common:administrative-status;
    description
      "This administrative status reflects that a request is
       pending an adiministrator approval.";
  }

  identity awaiting-processing {
    base vpn-common:administrative-status;
    description
      "This administrative status reflects that a request was
       approved and validated, but is awaiting more processing
       before activation.";
  }

  identity admin-prohibited {
    base vpn-common:administrative-status;
    description
      "This administrative status reflects that a request cannot
       be handled because of administrative policies.";
  }

  identity rejected {
    base vpn-common:administrative-status;
    description
      "This administrative status reflects that a request was
       rejected because, e.g., there are no sufficient resources
       or other reasons not covered by the other status types.";
  }

  /****************************Typedefs************************/

  typedef predefined-next-hop {
    type identityref {
      base local-defined-next-hop;
    }
    description
      "Predefined next-hop designation for locally generated
       routes.";
  }

  typedef area-address {
    type string {
      pattern '[0-9A-Fa-f]{2}(\.[0-9A-Fa-f]{4}){0,6}';
    }
    description
      "This type defines the area address format.";
  }

  /************************Reusable groupings********************/
  /**** Service Status ****/

  grouping service-status {
    description
      "Service status grouping.";
    container status {
      description
        "Service status.";
      container admin-status {
        description
          "Administrative service status.";
        leaf status {
          type identityref {
            base vpn-common:administrative-status;
          }
          description
            "Administrative service status.";
        }
        leaf last-change {
          type yang:date-and-time;
          config false;
          description
            "Indicates the actual date and time of the service
             status change.";
        }
      }
      container oper-status {
        config false;
        description
          "Operational service status.";
        uses vpn-common:oper-status-timestamp;
      }
    }
  }


  /**** A set of profiles ****/

  grouping ac-profile-cfg {
    description
      "Grouping for AC profile configuration.";
    container valid-provider-identifiers {
      description
        "Container for valid provider profile identifiers.
         The profiles only have significance within the service
         provider's administrative domain.";
      list encryption-profile-identifier {
        key "id";
        description
          "List of encryption profile identifiers.";
        leaf id {
          type string;
          description
            "Identification of the encryption profile to be used.";
        }
      }
      list qos-profile-identifier {
        key "id";
        description
          "List of QoS profile identifiers.";
        leaf id {
          type string;
          description
            "Identification of the QoS profile to be used.";
        }
      }
      list failure-detection-profile-identifier {
        key "id";
        description
          "List of BFD profile identifiers.";
        leaf id {
          type string;
          description
            "Identification of the a failure detection (e.g., BFD)
             profile to be used.";
        }
      }
      list forwarding-profile-identifier {
        key "id";
        description
          "List of forwarding profile identifiers.";
        leaf id {
          type string;
          description
            "Identification of the forwarding profile to be used.";
        }
      }
      list routing-profile-identifier {
        key "id";
        description
          "List of routing profile identifiers.";
        leaf id {
          type string;
          description
            "Identification of the routing profile to be used by
             the routing protocols over an AC.";
        }
      }
      nacm:default-deny-write;
    }
  }

  /**** Operational instructions ****/

  grouping op-instructions {
    description
      "Scheduling instructions.";
    leaf requested-start {
      type yang:date-and-time;
      description
        "Indicates the requested date and time when the service is
         expected to be active.";
    }
    leaf requested-stop {
      type yang:date-and-time;
      description
        "Indicates the requested date and time when the service is
         expected to be disabled.";
    }
    leaf actual-start {
      type yang:date-and-time;
      config false;
      description
        "Indicates the actual date and time when the service
         actually was enabled.";
    }
    leaf actual-stop {
      type yang:date-and-time;
      config false;
      description
        "Indicates the actual date and time when the service
         actually was disabled.";
    }
  }

  /**** Layer 2 encapsulations ****/
  // Dot1q

  grouping dot1q {
    description
      "Defines a grouping for tagged interfaces.";
    leaf tag-type {
      type identityref {
        base vpn-common:tag-type;
      }
      description
        "Tag type.";
    }
    leaf cvlan-id {
      type uint16 {
        range "1..4094";
      }
      description
        "VLAN identifier.";
    }
  }

  // priority-tagged

  grouping priority-tagged {
    description
      "Priority tagged.";
    leaf tag-type {
      type identityref {
        base vpn-common:tag-type;
      }
      description
        "Tag type.";
    }
  }

  // QinQ

  grouping qinq {
    description
      "Includes QinQ parameters.";
    leaf tag-type {
      type identityref {
        base vpn-common:tag-type;
      }
      description
        "Tag type.";
    }
    leaf svlan-id {
      type uint16 {
        range "1..4094";
      }
      description
        "Service VLAN (S-VLAN) identifier.";
    }
    leaf cvlan-id {
      type uint16 {
        range "1..4094";
      }
      description
        "Customer VLAN (C-VLAN) identifier.";
    }
  }

  /**** Layer 2 tunnel services ****/
  // pseudowire (PW)

  grouping pseudowire {
    description
      "Includes pseudowire termination parameters.";
    leaf vcid {
      type uint32;
      description
        "Indicates a PW or virtual circuit (VC) identifier.";
    }
    leaf far-end {
      type union {
        type uint32;
        type inet:ip-address;
      }
      description
        "Neighbor reference.";
      reference
        "RFC 8077: Pseudowire Setup and Maintenance Using the Label
                   Distribution Protocol (LDP), Section 6.1";
    }
  }

  // VPLS

  grouping vpls {
    description
      "VPLS termination parameters.";
    leaf vcid {
      type uint32;
      description
        "VC identifier.";
    }
    leaf-list far-end {
      type union {
        type uint32;
        type inet:ip-address;
      }
      description
        "Neighbor reference.";
    }
  }

  // VXLAN

  grouping vxlan {
    description
      "VXLAN termination parameters.";
    leaf vni-id {
      type uint32;
      description
        "VXLAN Network Identifier (VNI).";
    }
    leaf peer-mode {
      type identityref {
        base vpn-common:vxlan-peer-mode;
      }
      description
        "Specifies the VXLAN access mode. By default,
         the peer mode is set to 'static-mode'.";
    }
    leaf-list peer-ip-address {
      type inet:ip-address;
      description
        "List of a peer's IP addresses.";
    }
  }

  // Layer 2 Tunnel service

  grouping l2-tunnel-service {
    description
      "Defines a Layer 2 tunnel termination.";
    leaf type {
      type identityref {
        base l2-tunnel-type;
      }
      description
        "Selects the tunnel termination type for an AC.";
    }
    container pseudowire {
      when "derived-from-or-self(../type, 'ac-common:pseudowire')" {
        description
          "Only applies when the Layer 2 service type is
           'pseudowire'.";
      }
      description
        "Includes pseudowire termination parameters.";
      uses pseudowire;
    }
    container vpls {
      when "derived-from-or-self(../type, 'ac-common:vpls')" {
        description
          "Only applies when the Layer 2 service type is 'vpls'.";
      }
      description
        "VPLS termination parameters.";
      uses vpls;
    }
    container vxlan {
      when "derived-from-or-self(../type, 'ac-common:vxlan')" {
        description
          "Only applies when the Layer 2 service type is 'vxlan'.";
      }
      description
        "VXLAN termination parameters.";
      uses vxlan;
    }
  }

  /**** Layer 3 connection *****/
  // IPv4 allocation type

  grouping ipv4-allocation-type {
    description
      "IPv4-specific parameters.";
    leaf prefix-length {
      type uint8 {
        range "0..32";
      }
      description
        "Subnet prefix length expressed in bits. It is applied to
         both local and customer addresses.";
    }
    leaf address-allocation-type {
      type identityref {
        base address-allocation-type;
      }
      must "not(derived-from-or-self(current(), 'ac-common:slaac') "
         + "or derived-from-or-self(current(), "
         + "'ac-common:provider-dhcp-slaac'))" {
        error-message "SLAAC is only applicable to IPv6.";
      }
      description
        "Defines how IPv4 addresses are allocated to the peer site.";
    }
  }

  // IPv6 allocation type

  grouping ipv6-allocation-type {
    description
      "IPv6-specific parameters.";
    leaf prefix-length {
      type uint8 {
        range "0..128";
      }
      description
        "Subnet prefix length expressed in bits. It is applied to
          both local and customer addresses.";
    }
    leaf address-allocation-type {
      type identityref {
        base address-allocation-type;
      }
      description
        "Defines how IPv6 addresses are allocated to the peer site.";
    }
  }

  // Basic parameters for IPv4 connection

  grouping ipv4-connection-basic {
    description
      "Basic set fof IPv4-specific parameters for the connection.";
    uses ipv4-allocation-type;
    choice allocation-type {
      description
        "Choice of the IPv4 address allocation.";
      case dynamic {
        description
          "When the addresses are allocated by DHCP or other dynamic
           means local to the infrastructure.";
        choice provider-dhcp {
          description
            "Parameters related to DHCP-allocated addresses. IP
             addresses are allocated by DHCP, that is provided by
             the operator.";
          leaf dhcp-service-type {
            type enumeration {
              enum server {
                description
                  "Local DHCP server.";
              }
              enum relay {
                description
                  "Local DHCP relay.  DHCP requests are relayed to
                   a provider's server.";
              }
            }
            description
              "Indicates the type of DHCP service to be enabled on
               an AC.";
          }
        }
        choice dhcp-relay {
          description
            "The DHCP relay is provided by the operator.";
          container customer-dhcp-servers {
            description
              "Container for a list of the customer's DHCP servers.";
            leaf-list server-ip-address {
              type inet:ipv4-address;
              description
                "IPv4 addresses of the customer's DHCP server.";
            }
          }
        }
      }
    }
  }

  // Basic parameters for IPv6 connection

  grouping ipv6-connection-basic {
    description
      "Basic set fof IPv6-specific parameters for the connection.";
    uses ipv6-allocation-type;
    choice allocation-type {
      description
        "Choice of the IPv6 address allocation.";
      case dynamic {
        description
          "When the addresses are allocated by DHCP or other dynamic
           means local to the infrastructure.";
        choice provider-dhcp {
          description
            "Parameters related to DHCP-allocated addresses.
             IP addresses are allocated by DHCP, that is provided
             by the operator.";
          leaf dhcp-service-type {
            type enumeration {
              enum server {
                description
                  "Local DHCP server.";
              }
              enum relay {
                description
                  "Local DHCP relay.  DHCP requests are relayed to a
                   provider's server.";
              }
            }
            description
              "Indicates the type of DHCP service to be enabled on
               the AC.";
          }
        }
        choice dhcp-relay {
          description
            "The DHCP relay is provided by the operator.";
          container customer-dhcp-servers {
            description
              "Container for a list of the customer's DHCP servers.";
            leaf-list server-ip-address {
              type inet:ipv6-address;
              description
                "IPv6 addresses of the customer's DHCP server.";
            }
          }
        }
      }
    }
  }

  // Full parameters for the IPv4 connection

  grouping ipv4-connection {
    description
      "IPv4-specific parameters.";
    leaf local-address {
      type inet:ipv4-address;
      description
        "The IP address used at the provider's interface.";
    }
    leaf virtual-address {
      type inet:ipv4-address;
      description
        "This addresss may be used for redundancy purposes.";
    }
    uses ipv4-allocation-type;
    choice allocation-type {
      description
        "Choice of the IPv4 address allocation.";
      case dynamic {
        description
          "When the addresses are allocated by DHCP or other
           dynamic means local to the infrastructure.";
        choice address-assign {
          description
            "A choice for how IPv4 addresses are assigned.";
          case number {
            leaf number-of-dynamic-address {
              type uint16;
              description
                "Specifies the number of IP addresses to be assigned
                 to the customer on the AC.";
            }
          }
          case explicit {
            container customer-addresses {
              description
                "Container for customer addresses to be allocated
                 using DHCP.";
              list address-pool {
                key "pool-id";
                description
                  "Describes IP addresses to be dyncamically
                   allocated.

                   When only 'start-address' is present, it
                   represents a single address.

                   When both 'start-address' and 'end-address' are
                   specified, it implies a range inclusive of both
                   addresses.";
                leaf pool-id {
                  type string;
                  description
                    "A pool identifier for the address range from
                     'start-address' to 'end-address'.";
                }
                leaf start-address {
                  type inet:ipv4-address;
                  mandatory true;
                  description
                    "Indicates the first address in the pool.";
                }
                leaf end-address {
                  type inet:ipv4-address;
                  description
                    "Indicates the last address in the pool.";
                }
              }
            }
          }
        }
        choice provider-dhcp {
          description
            "Parameters related to DHCP-allocated addresses. IP
             addresses are allocated by DHCP, which is provided by
             the operator.";
          leaf dhcp-service-type {
            type enumeration {
              enum server {
                description
                  "Local DHCP server.";
              }
              enum relay {
                description
                  "Local DHCP relay.  DHCP requests are relayed to
                   a provider's server.";
              }
            }
            description
              "Indicates the type of DHCP service to be enabled on
               this AC.";
          }
        }
        choice dhcp-relay {
          description
            "The DHCP relay is provided by the operator.";
          container customer-dhcp-servers {
            description
              "Container for a list of the customer's DHCP servers.";
            leaf-list server-ip-address {
              type inet:ipv4-address;
              description
                "IPv4 addresses of the customer's DHCP server.";
            }
          }
        }
      }
      case static-addresses {
        description
          "Lists the IPv4 addresses that are used.";
        list address {
          key "address-id";
          ordered-by user;
          description
            "Lists the IPv4 addresses that are used. The first
             address of the list is the primary address of the
             connection.";
          leaf address-id {
            type string;
            description
              "An identifier of the static IPv4 address.";
          }
          leaf customer-address {
            type inet:ipv4-address;
            description
              "An IPv4 address of the customer side.";
          }
        }
      }
    }
  }

  // Full parameters for the IPv6 connection

  grouping ipv6-connection {
    description
      "IPv6-specific parameters.";
    leaf local-address {
      type inet:ipv6-address;
      description
        "IPv6 address of the provider side.";
    }
    leaf virtual-address {
      type inet:ipv6-address;
      description
        "This addresss may be used for redundancy purposes.";
    }
    uses ipv6-allocation-type;
    choice allocation-type {
      description
        "Choice of the IPv6 address allocation.";
      case dynamic {
        description
          "When the addresses are allocated by DHCP or other
           dynamic means local to the infrastructure.";
        choice address-assign {
          description
            "A choice for how IPv6 addresses are assigned.";
          case number {
            leaf number-of-dynamic-address {
              type uint16;
              description
                "Specifies the number of IP addresses to be
                 assigned to the customer on this access.";
            }
          }
          case explicit {
            container customer-addresses {
              description
                "Container for customer addresses to be allocated
                 using DHCP.";
              list address-pool {
                key "pool-id";
                description
                  "Describes IP addresses to be dyncamically
                   allocated.

                   When only 'start-address' is present, it
                   represents a single address.

                   When both 'start-address' and 'end-address' are
                   specified, it implies a range inclusive of both
                   addresses.";
                leaf pool-id {
                  type string;
                  description
                    "A pool identifier for the address range from
                     'start-address' to 'end-address'.";
                }
                leaf start-address {
                  type inet:ipv6-address;
                  mandatory true;
                  description
                    "Indicates the first address in the pool.";
                }
                leaf end-address {
                  type inet:ipv6-address;
                  description
                    "Indicates the last address in the pool.";
                }
              }
            }
          }
        }
        choice provider-dhcp {
          description
            "Parameters related to DHCP-allocated addresses.
             IP addresses are allocated by DHCP, which is provided
             by the operator.";
          leaf dhcp-service-type {
            type enumeration {
              enum server {
                description
                  "Local DHCP server.";
              }
              enum relay {
                description
                  "Local DHCP relay.  DHCP requests are relayed
                   to a provider's server.";
              }
            }
            description
              "Indicates the type of DHCP service to
               be enabled on this access.";
          }
        }
        choice dhcp-relay {
          description
            "The DHCP relay is provided by the operator.";
          container customer-dhcp-servers {
            description
              "Container for a list of the customer's DHCP servers.";
            leaf-list server-ip-address {
              type inet:ipv6-address;
              description
                "IPv6 addresses of the customer's DHCP server.";
            }
          }
        }
      }
      case static-addresses {
        description
          "Lists the IPv6 addresses that are used.";
        list address {
          key "address-id";
          ordered-by user;
          description
            "Lists the IPv6 addresses that are used. The first
             address of the list is the primary IP address of
             the connection.";
          leaf address-id {
            type string;
            description
              "An identifier of the static IPv6 address.";
          }
          leaf customer-address {
            type inet:ipv6-address;
            description
              "An IPv6 address of the customer side.";
          }
        }
      }
    }
  }

  /**** Routing ****/
  // Routing authentication

  grouping bgp-authentication {
    description
      "Grouping for BGP authentication parameters.";
    container authentication {
      description
        "Container for BGP authentication  parameters.";
      leaf enabled {
        type boolean;
        description
          "Enables or disables authentication.";
      }
      container keying-material {
        when "../enabled = 'true'";
        description
          "Container for describing how a BGP routing session is to
           be secured on an AC.";
        choice option {
          description
            "Choice of authentication options.";
          case ao {
            description
              "Uses the TCP Authentication Option (TCP-AO).";
            reference
              "RFC 5925: The TCP Authentication Option";
            leaf enable-ao {
              type boolean;
              description
                "Enables the TCP-AO.";
            }
            leaf ao-keychain {
              type key-chain:key-chain-ref;
              description
                "Reference to the TCP-AO key chain.";
              reference
                "RFC 8177: YANG Data Model for Key Chains";
            }
          }
          case md5 {
            description
              "Uses MD5 to secure the session.";
            reference
              "RFC 4364: BGP/MPLS IP Virtual Private Networks
                         (VPNs), Section 13.2";
            leaf md5-keychain {
              type key-chain:key-chain-ref;
              description
                "Reference to the MD5 key chain.";
              reference
                "RFC 8177: YANG Data Model for Key Chains";
            }
          }
          case explicit {
            leaf key-id {
              type uint32;
              description
                "Key identifier.";
            }
            leaf key {
              type string;
              description
                "BGP authentication key.

                 This model only supports the subset of keys that
                 are representable as ASCII strings.";
            }
            leaf crypto-algorithm {
              type identityref {
                base key-chain:crypto-algorithm;
              }
              description
                "Indicates the cryptographic algorithm associated
                 with the key.";
            }
          }
        }
      }
    }
  }

  grouping ospf-authentication {
    description
      "Authentication configuration.";
    container authentication {
      description
        "Container for OSPF authentication  parameters.";
      leaf enabled {
        type boolean;
        description
          "Enables or disables authentication.";
      }
      container keying-material {
        when "../enabled = 'true'";
        description
          "Container for describing how an OSPF session is to be
           secured for this AC.";
        choice option {
          description
            "Options for OSPF authentication.";
          case auth-key-chain {
            leaf key-chain {
              type key-chain:key-chain-ref;
              description
                "Name of the key chain.";
            }
          }
          case auth-key-explicit {
            leaf key-id {
              type uint32;
              description
                "Key identifier.";
            }
            leaf key {
              type string;
              description
                "OSPF authentication key.

                 This model only supports the subset of keys that
                 are representable as ASCII strings.";
            }
            leaf crypto-algorithm {
              type identityref {
                base key-chain:crypto-algorithm;
              }
              description
                "Indicates the cryptographic algorithm associated
                 with the key.";
            }
          }
        }
      }
    }
  }

  grouping isis-authentication {
    description
      "IS-IS authentication configuration.";
    container authentication {
      description
        "Container for IS-IS authentication  parameters.";
      leaf enabled {
        type boolean;
        description
          "Enables or disables authentication.";
      }
      container keying-material {
        when "../enabled = 'true'";
        description
          "Container for describing how an IS-IS session is secured
           over an AC.";
        choice option {
          description
            "Options for IS-IS authentication.";
          case auth-key-chain {
            leaf key-chain {
              type key-chain:key-chain-ref;
              description
                "Name of the key chain.";
            }
          }
          case auth-key-explicit {
            leaf key-id {
              type uint32;
              description
                "Key identifier.";
            }
            leaf key {
              type string;
              description
                "IS-IS authentication key.

                 This model only supports the subset of keys that
                 are representable as ASCII strings.";
            }
            leaf crypto-algorithm {
              type identityref {
                base key-chain:crypto-algorithm;
              }
              description
                "Indicates the cryptographic algorithm associated
                 with the key.";
            }
          }
        }
      }
    }
  }

  grouping rip-authentication {
    description
      "RIP authentication configuration.";
    container authentication {
      description
        "Container for RIP authentication  parameters.";
      leaf enabled {
        type boolean;
        description
          "Enables or disables authentication.";
      }
      container keying-material {
        when "../enabled = 'true'";
        description
          "Container for describing how a RIP session is to be
           secured on this AC.";
        choice option {
          description
            "Specifies the authentication
             scheme.";
          case auth-key-chain {
            leaf key-chain {
              type key-chain:key-chain-ref;
              description
                "Name of the key chain.";
            }
          }
          case auth-key-explicit {
            leaf key {
              type string;
              description
                "RIP authentication key.

                 This model only supports the subset of keys that
                 are representable as ASCII strings.";
            }
            leaf crypto-algorithm {
              type identityref {
                base key-chain:crypto-algorithm;
              }
              description
                "Indicates the cryptographic algorithm associated
                 with the key.";
            }
          }
        }
      }
    }
  }

  // Basic routing parameters

  grouping bgp-peer-group-without-name {
    description
      "Identifies a BGP peer-group configured on the local system.";
    leaf local-as {
      type inet:as-number;
      description
        "Indicates a local AS Number (ASN). This ASN is exposed
         to a customer so that it knows which ASN to use
         to set up a BGP session.";
    }
    leaf peer-as {
      type inet:as-number;
      description
        "Indicates the customer's ASN when the customer
         requests BGP routing.";
    }
    leaf address-family {
      type identityref {
        base vpn-common:address-family;
      }
      description
        "This node contains the address families to be activated.
         'dual-stack' means that both IPv4 and IPv6 will be
         activated.";
    }
  }

  grouping bgp-peer-group-with-name {
    description
      "Identifies a BGP peer-group configured on the local system -
       identified by a peer-group name.";
    leaf name {
      type string;
      description
        "Name of the BGP peer-group.";
    }
    uses bgp-peer-group-without-name;
  }

  grouping ospf-basic {
    description
      "Configuration specific to OSPF.";
    leaf address-family {
      type identityref {
        base vpn-common:address-family;
      }
      description
        "Indicates whether IPv4, IPv6, or both are to be activated.";
    }
    leaf area-id {
      type yang:dotted-quad;
      mandatory true;
      description
        "Area ID.";
      reference
        "RFC 4577: OSPF as the Provider/Customer Edge Protocol
                   for BGP/MPLS IP Virtual Private Networks
                   (VPNs), Section 4.2.3
         RFC 6565: OSPFv3 as a Provider Edge to Customer Edge
                   (PE-CE) Routing Protocol, Section 4.2";
    }
    leaf metric {
      type uint16;
      description
        "Metric of the AC.  It is used in the routing state
         calculation and path selection.";
    }
  }

  grouping isis-basic {
    description
      "Basic configuration specific to IS-IS.";
    leaf address-family {
      type identityref {
        base vpn-common:address-family;
      }
      description
        "Indicates whether IPv4, IPv6, or both are to be activated.";
    }
    leaf area-address {
      type area-address;
      mandatory true;
      description
        "Area address.";
    }
  }

  // Static routing

  grouping ipv4-static-rtg-entry {
    description
      "Paramters to configure a specific IPv4 static routing entry.";
    leaf lan {
      type inet:ipv4-prefix;
      description
        "LAN prefix.";
    }
    leaf lan-tag {
      type string;
      description
        "Internal tag to be used in service policies.";
    }
    leaf next-hop {
      type union {
        type inet:ip-address;
        type predefined-next-hop;
      }
      description
        "The next hop that is to be used for the static route.
         This may be specified as an IP address or a
         predefined next-hop type (e.g., 'discard' or
         'local-link').";
    }
    leaf metric {
      type uint32;
      description
        "Indicates the metric associated with the static route.";
    }
  }

  grouping ipv4-static-rtg {
    description
      "Configuration specific to IPv4 static routing.";
    list ipv4-lan-prefixes {
      if-feature "vpn-common:ipv4";
      key "lan next-hop";
      description
        "List of LAN prefixes for the site.";
      uses ipv4-static-rtg-entry;
      uses ac-common:service-status;
    }
  }

  grouping ipv6-static-rtg-entry {
    description
      "Paramters to configure a specific IPv6 static routing entry.";
    leaf lan {
      type inet:ipv6-prefix;
      description
        "LAN prefixes.";
    }
    leaf lan-tag {
      type string;
      description
        "Internal tag to be used in service (e.g., VPN) policies.";
    }
    leaf next-hop {
      type union {
        type inet:ip-address;
        type predefined-next-hop;
      }
      description
        "The next hop that is to be used for the static route.
         This may be specified as an IP address or a predefined
         next-hop type (e.g., 'discard' or 'local-link').";
    }
    leaf metric {
      type uint32;
      description
        "Indicates the metric associated with the static route.";
    }
  }

  grouping ipv6-static-rtg {
    description
      "Configuration specific to IPv6 static routing.";
    list ipv6-lan-prefixes {
      if-feature "vpn-common:ipv6";
      key "lan next-hop";
      description
        "List of LAN prefixes for the site.";
      uses ipv6-static-rtg-entry;
      uses ac-common:service-status;
    }
  }

  // OAM

  grouping bfd {
    description
      "A grouping for basic BFD.";
    leaf holdtime {
      type uint32;
      units "milliseconds";
      description
        "Expected BFD holdtime.
         The customer may impose some fixed values
         for the holdtime period if the provider allows
         the customer to use this function.
         If the provider doesn't allow the customer to
         use this function, fixed values will not be set.";
      reference
        "RFC 5880: Bidirectional Forwarding Detection (BFD),
                   Section 6.8.18";
    }
  }

  // redundancy

  grouping redundancy-group {
    description
      "A grouping for redundancy group.";
    list group {
       key "group-id";
       description
         "List of group-ids.";
       leaf group-id {
         type string;
         description
           "Indicates the group-id to which the AC belongs.";
       }
       leaf precedence {
         type identityref {
           base ac-common:precedence-type;
         }
         description
           "Defines redundancy of an AC.";
       }
     }
   }

  // QoS

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

  grouping bandwidth-per-type {
    description
      "Grouping for bandwidth per type.";
    list bandwidth {
      key "bw-type";
      description
        "List for bandwidth per type data nodes.";
      leaf bw-type {
        type identityref {
          base vpn-common:bw-type;
        }
        description
          "Indicates the bandwidth type.";
      }
      choice type {
        description
          "Choice based upon bandwidth type.";
        case per-cos {
          description
            "Bandwidth per CoS.";
          list cos {
            key "cos-id";
            description
              "List of Class of Services.";
            leaf cos-id {
              type uint8;
              description
                "Identifier of the CoS, indicated by a Differentiated
                 Services Code Point (DSCP) or a CE-CLAN CoS (802.1p)
                 value in the service frame.";
              reference
                "IEEE Std 802.1Q: Bridges and Bridged Networks";
            }
            uses bandwidth-parameters;
          }
        }
        case other {
          description
            "Other bandwidth types.";
          uses bandwidth-parameters;
        }
      }
    }
  }
}

<CODE ENDS>

6. Security Considerations

This section uses the template described in Section 3.7 of [I-D.ietf-netmod-rfc8407bis].

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

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

The "ietf-ac-common" module defines a set of identities, types, and groupings. These nodes are intended to be reused by other YANG modules. The module by itself does not expose any data nodes that are writable, data nodes that contain read-only state, or RPCs.

YANG modules that use the groupings that are defined in this document should identify the corresponding security considerations. For example, reusing some of these groupings will expose privacy-related information (e.g., 'ipv6-lan-prefixes' or 'ipv4-lan-prefixes'). Disclosing such information may be considered a violation of the customer-provider trust relationship.

Several groupings ('bgp-authentication', 'ospf-authentication', 'isis-authentication', and 'rip-authentication') rely upon [RFC8177] for authentication purposes. As such, modules that will reuse these groupings will inherit the security considerations discussed in Section 5 of [RFC8177]. Also, these groupings support supplying explicit keys as strings in ASCII format. The use of keys in hexadecimal string format would afford greater key entropy with the same number of key- string octets. However, such a format is not included in this version of the common AC model, because it is not supported by the underlying device modules (e.g., [RFC8695]).

7. IANA Considerations

IANA is requested to register the following URI in the "ns" subregistry within the "IETF XML Registry" [RFC3688]:

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

IANA is requested to register the following YANG module in the "YANG Module Names" subregistry [RFC6020] within the "YANG Parameters" registry:

   Name:  ietf-ac-common
   Namespace:  urn:ietf:params:xml:ns:yang:ietf-ac-common
   Prefix:  ac-common
   Maintained by IANA?  N
   Reference:  RFC XXXX

8. References

8.1. Normative References

[ISO10589]
ISO, "Information technology - Telecommunications and information exchange between systems - Intermediate System to Intermediate System intra-domain routeing information exchange protocol for use in conjunction with the protocol for providing the connectionless-mode network service (ISO8473)", , <https://www.iso.org/standard/30932.html>.
[RFC1195]
Callon, R., "Use of OSI IS-IS for routing in TCP/IP and dual environments", RFC 1195, DOI 10.17487/RFC1195, , <https://www.rfc-editor.org/rfc/rfc1195>.
[RFC2080]
Malkin, G. and R. Minnear, "RIPng for IPv6", RFC 2080, DOI 10.17487/RFC2080, , <https://www.rfc-editor.org/rfc/rfc2080>.
[RFC2453]
Malkin, G., "RIP Version 2", STD 56, RFC 2453, DOI 10.17487/RFC2453, , <https://www.rfc-editor.org/rfc/rfc2453>.
[RFC3688]
Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, , <https://www.rfc-editor.org/rfc/rfc3688>.
[RFC4271]
Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A Border Gateway Protocol 4 (BGP-4)", RFC 4271, DOI 10.17487/RFC4271, , <https://www.rfc-editor.org/rfc/rfc4271>.
[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, , <https://www.rfc-editor.org/rfc/rfc4577>.
[RFC5308]
Hopps, C., "Routing IPv6 with IS-IS", RFC 5308, DOI 10.17487/RFC5308, , <https://www.rfc-editor.org/rfc/rfc5308>.
[RFC5492]
Scudder, J. and R. Chandra, "Capabilities Advertisement with BGP-4", RFC 5492, DOI 10.17487/RFC5492, , <https://www.rfc-editor.org/rfc/rfc5492>.
[RFC5925]
Touch, J., Mankin, A., and R. Bonica, "The TCP Authentication Option", RFC 5925, DOI 10.17487/RFC5925, , <https://www.rfc-editor.org/rfc/rfc5925>.
[RFC6020]
Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, , <https://www.rfc-editor.org/rfc/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, , <https://www.rfc-editor.org/rfc/rfc6241>.
[RFC6242]
Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, , <https://www.rfc-editor.org/rfc/rfc6242>.
[RFC6565]
Pillay-Esnault, P., Moyer, P., Doyle, J., Ertekin, E., and M. Lundberg, "OSPFv3 as a Provider Edge to Customer Edge (PE-CE) Routing Protocol", RFC 6565, DOI 10.17487/RFC6565, , <https://www.rfc-editor.org/rfc/rfc6565>.
[RFC6991]
Schoenwaelder, J., Ed., "Common YANG Data Types", RFC 6991, DOI 10.17487/RFC6991, , <https://www.rfc-editor.org/rfc/rfc6991>.
[RFC7348]
Mahalingam, M., Dutt, D., Duda, K., Agarwal, P., Kreeger, L., Sridhar, T., Bursell, M., and C. Wright, "Virtual eXtensible Local Area Network (VXLAN): A Framework for Overlaying Virtualized Layer 2 Networks over Layer 3 Networks", RFC 7348, DOI 10.17487/RFC7348, , <https://www.rfc-editor.org/rfc/rfc7348>.
[RFC8040]
Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, , <https://www.rfc-editor.org/rfc/rfc8040>.
[RFC8077]
Martini, L., Ed. and G. Heron, Ed., "Pseudowire Setup and Maintenance Using the Label Distribution Protocol (LDP)", STD 84, RFC 8077, DOI 10.17487/RFC8077, , <https://www.rfc-editor.org/rfc/rfc8077>.
[RFC8177]
Lindem, A., Ed., Qu, Y., Yeung, D., Chen, I., and J. Zhang, "YANG Data Model for Key Chains", RFC 8177, DOI 10.17487/RFC8177, , <https://www.rfc-editor.org/rfc/rfc8177>.
[RFC8341]
Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, , <https://www.rfc-editor.org/rfc/rfc8341>.
[RFC8342]
Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K., and R. Wilton, "Network Management Datastore Architecture (NMDA)", RFC 8342, DOI 10.17487/RFC8342, , <https://www.rfc-editor.org/rfc/rfc8342>.
[RFC8446]
Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, , <https://www.rfc-editor.org/rfc/rfc8446>.
[RFC9181]
Barguil, S., Gonzalez de Dios, O., Ed., Boucadair, M., Ed., and Q. Wu, "A Common YANG Data Model for Layer 2 and Layer 3 VPNs", RFC 9181, DOI 10.17487/RFC9181, , <https://www.rfc-editor.org/rfc/rfc9181>.

8.2. Informative References

[AC-Common-Tree]
"Full Common Attachment Circuit Tree Structure", , <https://github.com/boucadair/attachment-circuit-model/blob/main/yang/full-trees/ac-common-with-groupings.txt>.
[I-D.ietf-netmod-rfc8407bis]
Bierman, A., Boucadair, M., and Q. Wu, "Guidelines for Authors and Reviewers of Documents Containing YANG Data Models", Work in Progress, Internet-Draft, draft-ietf-netmod-rfc8407bis-11, , <https://datatracker.ietf.org/doc/html/draft-ietf-netmod-rfc8407bis-11>.
[I-D.ietf-opsawg-ac-lxsm-lxnm-glue]
Boucadair, M., Roberts, R., Barguil, S., and O. G. de Dios, "A YANG Data Model for Augmenting VPN Service and Network Models with Attachment Circuits", Work in Progress, Internet-Draft, draft-ietf-opsawg-ac-lxsm-lxnm-glue-09, , <https://datatracker.ietf.org/doc/html/draft-ietf-opsawg-ac-lxsm-lxnm-glue-09>.
[I-D.ietf-opsawg-ntw-attachment-circuit]
Boucadair, M., Roberts, R., de Dios, O. G., Barguil, S., and B. Wu, "A Network YANG Data Model for Attachment Circuits", Work in Progress, Internet-Draft, draft-ietf-opsawg-ntw-attachment-circuit-09, , <https://datatracker.ietf.org/doc/html/draft-ietf-opsawg-ntw-attachment-circuit-09>.
[I-D.ietf-opsawg-teas-attachment-circuit]
Boucadair, M., Roberts, R., de Dios, O. G., Barguil, S., and B. Wu, "YANG Data Models for Bearers and 'Attachment Circuits'-as-a-Service (ACaaS)", Work in Progress, Internet-Draft, draft-ietf-opsawg-teas-attachment-circuit-11, , <https://datatracker.ietf.org/doc/html/draft-ietf-opsawg-teas-attachment-circuit-11>.
[I-D.ietf-teas-ietf-network-slice-nbi-yang]
Wu, B., Dhody, D., Rokui, R., Saad, T., and J. Mullooly, "A YANG Data Model for the RFC 9543 Network Slice Service", Work in Progress, Internet-Draft, draft-ietf-teas-ietf-network-slice-nbi-yang-13, , <https://datatracker.ietf.org/doc/html/draft-ietf-teas-ietf-network-slice-nbi-yang-13>.
[PYANG]
"pyang", , <https://github.com/mbj4668/pyang>.
[RFC2918]
Chen, E., "Route Refresh Capability for BGP-4", RFC 2918, DOI 10.17487/RFC2918, , <https://www.rfc-editor.org/rfc/rfc2918>.
[RFC4364]
Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, , <https://www.rfc-editor.org/rfc/rfc4364>.
[RFC4724]
Sangli, S., Chen, E., Fernando, R., Scudder, J., and Y. Rekhter, "Graceful Restart Mechanism for BGP", RFC 4724, DOI 10.17487/RFC4724, , <https://www.rfc-editor.org/rfc/rfc4724>.
[RFC4760]
Bates, T., Chandra, R., Katz, D., and Y. Rekhter, "Multiprotocol Extensions for BGP-4", RFC 4760, DOI 10.17487/RFC4760, , <https://www.rfc-editor.org/rfc/rfc4760>.
[RFC4862]
Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless Address Autoconfiguration", RFC 4862, DOI 10.17487/RFC4862, , <https://www.rfc-editor.org/rfc/rfc4862>.
[RFC7665]
Halpern, J., Ed. and C. Pignataro, Ed., "Service Function Chaining (SFC) Architecture", RFC 7665, DOI 10.17487/RFC7665, , <https://www.rfc-editor.org/rfc/rfc7665>.
[RFC7911]
Walton, D., Retana, A., Chen, E., and J. Scudder, "Advertisement of Multiple Paths in BGP", RFC 7911, DOI 10.17487/RFC7911, , <https://www.rfc-editor.org/rfc/rfc7911>.
[RFC8299]
Wu, Q., Ed., Litkowski, S., Tomotaki, L., and K. Ogaki, "YANG Data Model for L3VPN Service Delivery", RFC 8299, DOI 10.17487/RFC8299, , <https://www.rfc-editor.org/rfc/rfc8299>.
[RFC8340]
Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, , <https://www.rfc-editor.org/rfc/rfc8340>.
[RFC8466]
Wen, B., Fioccola, G., Ed., Xie, C., and L. Jalil, "A YANG Data Model for Layer 2 Virtual Private Network (L2VPN) Service Delivery", RFC 8466, DOI 10.17487/RFC8466, , <https://www.rfc-editor.org/rfc/rfc8466>.
[RFC8695]
Liu, X., Sarda, P., and V. Choudhary, "A YANG Data Model for the Routing Information Protocol (RIP)", RFC 8695, DOI 10.17487/RFC8695, , <https://www.rfc-editor.org/rfc/rfc8695>.
[RFC8969]
Wu, Q., Ed., Boucadair, M., Ed., Lopez, D., Xie, C., and L. Geng, "A Framework for Automating Service and Network Management with YANG", RFC 8969, DOI 10.17487/RFC8969, , <https://www.rfc-editor.org/rfc/rfc8969>.
[RFC9182]
Barguil, S., Gonzalez de Dios, O., Ed., Boucadair, M., Ed., Munoz, L., and A. Aguado, "A YANG Network Data Model for Layer 3 VPNs", RFC 9182, DOI 10.17487/RFC9182, , <https://www.rfc-editor.org/rfc/rfc9182>.
[RFC9291]
Boucadair, M., Ed., Gonzalez de Dios, O., Ed., Barguil, S., and L. Munoz, "A YANG Network Data Model for Layer 2 VPNs", RFC 9291, DOI 10.17487/RFC9291, , <https://www.rfc-editor.org/rfc/rfc9291>.
[RFC9408]
Boucadair, M., Ed., Gonzalez de Dios, O., Barguil, S., Wu, Q., and V. Lopez, "A YANG Network Data Model for Service Attachment Points (SAPs)", RFC 9408, DOI 10.17487/RFC9408, , <https://www.rfc-editor.org/rfc/rfc9408>.
[RFC9543]
Farrel, A., Ed., Drake, J., Ed., Rokui, R., Homma, S., Makhijani, K., Contreras, L., and J. Tantsura, "A Framework for Network Slices in Networks Built from IETF Technologies", RFC 9543, DOI 10.17487/RFC9543, , <https://www.rfc-editor.org/rfc/rfc9543>.

Acknowledgments

The document reuses many of the structures that were defined in [RFC9181] and [RFC9182].

Thanks to Ebben Aries for the YANG Doctors review, Andy Smith and Gyanh Mishra for the rtg-dir reviews.

Thanks to Reza Rokui for the Shepherd review.

Contributors

Victor Lopez
Nokia
Ivan Bykov
Ribbon Communications
Qin Wu
Huawei
Kenichi Ogaki
KDDI
Luis Angel Munoz
Vodafone

Authors' Addresses

Mohamed Boucadair (editor)
Orange
Richard Roberts (editor)
Juniper
Oscar Gonzalez de Dios
Telefonica
Samier Barguil Giraldo
Nokia
Bo Wu
Huawei Technologies