Interdomain Routing                                       A. Shaikh, Ed.                                             K. Patel
Internet-Draft                                                    Google                                                    Arrcus
Intended status: Standards Track                          R. Shakir, Ed.                         M. Jethanandani
Expires: January 19, 2017                            Jive Communications
                                                           K. Patel, Ed.
                                                                   Cisco November 11, 2018
                                                                S. Hares, Ed. Hares
                                                                  Huawei
                                                              K. D'Souza
                                                                    AT&T
                                                               D. Bansal
                                                               Microsoft
                                                                A. Clemm
                                                             A. Zhdankin
                                                                   Cisco
                                                         M. Jethanandani
                                                      Cisco Systems, Inc
                                                                  X. Liu
                                                                Ericsson
                                                           July 18, 2016
                                                            May 10, 2018

                BGP Model for Service Provider Networks
                      draft-ietf-idr-bgp-model-02
                      draft-ietf-idr-bgp-model-03

Abstract

   This document defines a YANG data model for configuring and managing
   BGP, including protocol, policy, and operational aspects based on
   data center, carrier and content provider operational requirements.

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 http://datatracker.ietf.org/drafts/current/. 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 January 19, 2017. November 11, 2018.

Copyright Notice

   Copyright (c) 2016 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info)
   (https://trustee.ietf.org/license-info) in effect on the date of
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   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Goals and approach  . . . . . . . . . . . . . . . . . . .   3   2
   2.  Model overview  . . . . . . . . . . . . . . . . . . . . . . .   4
     2.1.  BGP protocol configuration  . . . . . . . . . . . . . . .   5   4
     2.2.  Policy configuration overview . . . . . . . . . . . . . .   6
     2.3.  Operational state overview
   3.  Relation to other YANG data models  . . . . . . . . . . . . .   7
   4.  Security Considerations . .   7
   3.  Relation to other YANG data models . . . . . . . . . . . . .   8
   4.  Security . . . .   7
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   5.  IANA Considerations
     5.1.  URI Registration  . . . . . . . . . . . . . . . . . . . .   8
     5.2.  YANG Module Name Registration . . . . . . . . . . . . . .   8
   6.  YANG modules  . . . . . . . . . . . . . . . . . . . . . . . .   9
   7.  BGP main module and submodule for base items  . . . . . . . .   9  10
   8.  BGP types . . . . . . . . . . . . . . . . . . . . . . . . . .  60  49
   9.  BGP policy data . . . . . . . . . . . . . . . . . . . . . . .  69  58
   10. References  . . . . . . . Contributors  . . . . . . . . . . . . . . . . . .  93
     10.1.  Normative references . . . . . . . . . .  72
   11. Acknowledgements  . . . . . . . .  93
     10.2.  Informative references . . . . . . . . . . . . . .  72
   12. References  . . .  95
   Appendix A.  Acknowledgements . . . . . . . . . . . . . . . . . .  95
   Appendix B.  Change summary . . . .  72
     12.1.  Normative references . . . . . . . . . . . . . . .  96
     B.1.  Changes between revisions -01 and -02 . . .  72
     12.2.  Informative references . . . . . . .  96
     B.2.  Changes between revisions -00 and -01 . . . . . . . . . .  96  74
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  96  74

1.  Introduction

   YANG [RFC6020] is a data modeling language that was introduced to
   define data for managing networked devices using NETCONF [RFC6241].
   YANG is proving relevant beyond its initial confines, as bindings to
   other interfaces (e.g.  ReST) and encodings other than XML (e.g.
   JSON) are being defined.  Furthermore, YANG data models can be used
   as the basis of implementation for a number of interfaces, such as
   CLIs and programmatic APIs (e.g., see
   [I-D.talwar-rtgwg-grpc-use-cases]).

   This document describes a YANG [RFC7950] data model for the BGP
   [RFC4271] protocol, including various protocol extensions, policy
   configuration, as well as defining key operational state data.  The
   model is intended to be vendor-neutral, in order to allow operators
   to manage BGP configuration in heterogeneous environments with
   routers supplied by multiple vendors.  The model is also intended to
   be readily mapped to existing implementations to facilitate support
   from as large a set of routing hardware and software vendors as
   possible.

1.1.  Goals and approach

   The model covers the base BGP features that are deployed across major
   implementations and the common BGP configurations in use across a
   number of operator network deployments.  In particular, this model
   attempts to cover BGP features defined in BGP [RFC4271], BGP
   Communities Attribute [RFC1997], BGP Route Reflection [RFC4456],
   Multiprotocol Extensions for BGP-4 [RFC4760], [RFC3065], Autonomous System
   Confederations for BGP [RFC5065], BGP Route Flap Damping [RFC2439],
   Graceful Restart Mechanism for BGP [RFC4724], and BGP Prefix Origin
   Validation [RFC6811].

   Along with configuration of base BGP features, this model also
   addresses policy configuration, by providing "hooks" for applying
   policies, and also defining BGP-specific policy features.  The BGP
   policy features are intended to be used with the general routing
   policy model defined in A YANG Data Model for Routing Policy
   Management [I-D.ietf-rtgwg-policy-model].  The model
   also supports operational state data to provide a common model for
   reading BGP-related state from a BGP speaker. the
   NMDA [RFC8342] architecture.

   For the base BGP features, the focus of the model described in this
   document is on providing configuration and operational state
   information relating to:

   o  The global BGP instance, and neighbors whose configuration is
      specified individually, or templated with the use of peer-groups.

   o  The address families that are supported by peers, and the global
      configuration which relates to them.

   o  The policy configuration "hooks" and BGP-specific policy features
      that relate to a neighbor - controlling the import and export of
      NLRIs.

   As mentioned earlier, any configuration items that are deemed to be
   widely available in existing major BGP implementations are included
   in the model.  Additional, more esoteric, configuration items that
   are not commonly used, or only available from a single
   implementation, are omitted from the model with an expectation that
   they will be available in companion modules that augment or extend
   the current model.  This allows clarity in identifying data that is
   part of the vendor-neutral base model.

   Where possible, naming in the model follows conventions used in
   available standards documents, and otherwise tries to be self-
   explanatory with sufficient descriptions of the intended behavior.
   Similarly, configuration data value constraints and default values,
   where used, are based on recommendations in current standards
   documentation, or those commonly used in multiple implementations.
   Since implementations can vary widely in this respect, this version
   of the model specifies only a limited set of defaults and ranges with
   the expectation of being more prescriptive in future versions based
   on actual operator use.

2.  Model overview

   The BGP model is defined across several YANG modules and submodules,
   but at a high level is organized into six elements:

   o  base protocol configuration -- configuration affecting BGP
      protocol-related operations, defined at various levels of
      hierarchy.

   o  multiprotocol configuration -- configuration affecting individual
      address-families within BGP Multiprotocl Extensions for BGP-4
      [RFC4760].

   o  neighbor configuration -- configuration affecting an individual
      neighbor within BGP.

   o  neighbor multiprotocol configuration -- configuration affecting
      individual address-families for a neighbor within BGP.

   o  policy configuration -- hooks for application of the policies
      defined in A YANG Data Model for Routing Policy Management
      [I-D.ietf-rtgwg-policy-model] that act on routes sent (received)
      to (from) peers or other routing protocols and BGP-
      specific BGP-specific policy
      features.

   o  operational state -- variables used for monitoring and management
      of BGP operations.

   These modules also make use of standard Internet types, such as IP
   addresses and prefixes, autonomous system numbers, etc., defined in
   RFC 6991
   Common YANG Data Types [RFC6991].

   Throughout the model, the approach described in
   [I-D.openconfig-netmod-opstate] is used to represent

2.1.  BGP protocol configuration
   (intended state), operational and derived state data.  That

   The BGP protocol configuration model is to
   say, that each container holds a "config" and "state" sub-container -
   with the config container being used for configurable parameters, and
   the state container container holding both the operational state of
   configurable leaves, and derived counters and statistical
   information.

2.1.  BGP protocol configuration

   The BGP protocol configuration model is organized hierarchically,
   much like organized hierarchically,
   much like the majority of router implementations.  That is,
   configuration items can be specified at multiple levels, as shown
   below.

                 +--rw bgp!
                    +--rw global
                    |  +-- (global-configuration-options)
                    +--rw neighbors
                    |  +--rw neighbor* [neighbor-address]
                    |  +-- (neighbor-configuration-options)
                    +--rw peer-groups
                       +--rw peer-group* [peer-group-name]
                       +-- (neighbor-configuration-options)

   Users may specify configuration at a higher level and have it apply
   to all lower-level items, or provide overriding configuration at a
   lower level of the hierarchy.  Overriding configuration items are
   optional, with neighbor specific configuration being the most
   specific or lowest level, followed by peer-group, and finally global.
   Global configuration options reflect a subset of the peer-group or
   neighbor specific configuration options which are relevant to the
   entire BGP instance.

   The model makes the simplifying assumption that most of the
   configuration items are available at all levels of the hierarchy.
   That is, very little configuration is specific to a particular level
   in the hierarchy, other than obvious items such as "group-name" only
   being available for the peer group-level config.  A notable exception
   is for sub-address family configuration where some items are only
   applicable for a given AFI-SAFI combination.

   In order to allow common configuration to be applied to a set of
   neighbors, all neighbor configuration options are available within a
   peer-group.  A neighbor is associated to a particular peer-group
   through the use of a peer-group leaf (which provides a reference to a
   configured item in the peer-group list).

   Address-family configuration is made available in multiple points
   within the model - primarily within the global container, where
   instance-wide configuration can be set (for example, global protocol
   parameters, the BGP best path route selection options, or global
   policies relating to the address-family); and on a per-neighbor or
   per-peer-group basis, where address-families can be enabled or
   disabled, and policy associated with the parent entity applied.
   Within the afi-safi container, generic configuration that applies to
   all address-families (e.g., whether the AFI-SAFI is enabled) is
   presented at the top-level, with address-family specific containers
   made available for options relating to only that AFI-SAFI.  Within
   the current revision of the model a generic set of address-families,
   and common configuration and state options are included - further
   work is expected to add additional parameters to this area of the
   model.

   The following address-families are currently supported by the model:

           +--rw bgp!
             +--rw global
                +--rw afi-safis
                   +--rw afi-safi* [afi-safi-name]
                      +--rw afi-safi-name    -> ../config/afi-safi-name
                      |
                      +--rw ipv4-unicast
                      |     ...
                      +--rw ipv6-unicast
                      |     ...
                      +--rw ipv4-labelled-unicast
                      |     ...
                      +--rw ipv6-labelled-unicast
                      |     ...
                      +--rw l3vpn-ipv4-unicast
                      |     ...
                      +--rw l3vpn-ipv6-unicast
                      |     ...
                      +--rw l3vpn-ipv4-multicast
                      |     ...
                      +--rw l3vpn-ipv6-multicast
                      |     ...
                      +--rw l2vpn-vpls
                      |     ...
                      +--rw l2vpn-evpn
                      |     ...

2.2.  Policy configuration overview

   The BGP policy configuration model references the generic YANG
   routing policy model described in A YANG Data Model for Routing
   Policy Management [I-D.ietf-rtgwg-policy-model], which represents a
   condition-action policy framework for routing.  This model adds BGP-specific BGP-
   specific conditions (e.g., matching on the community attribute), and
   actions (e.g., setting local preference) to the generic policy
   framework.

   Policies that are defined in the routing-policy model are referenced
   in multiple places within the model:

   o  within the global instance, where a policy applies to all address-
      families for all peers.

   o  on a global AFI-SAFI basis, where policies apply to all peers for
      a particular address-family.

   o  on a per-peer-group or per-neighbor basis - where the policy
      applies to all address-families for the particular group or
      neighbor.

   o  on a per-afi-safi basis within a neighbor or peer-group context,
      where the policy is specific to the AFI-SAFI for a a specific
      neighbor or group.

              +--rw bgp
                 +--rw global
                 |  +--rw afi-safi
                 |  |  +--rw afi-safi* [afi-safi-name]
                 |  |     +--rw apply-policy
                 |  +--rw apply-policy
                 +--rw neighbors
                 |  +--rw neighbor* [neighbor-address]
                 |     +--rw afi-safi
                 |     |  +--rw afi-safi* [afi-safi-name]
                 |     |     +--rw apply-policy
                 |     +--rw apply-policy
                 +--rw peer-groups
                    +--rw peer-group* [peer-group-name]
                       +--rw afi-safi
                       |  +--rw afi-safi* [afi-safi-name]
                       |     +--rw apply-policy
                       +--rw apply-policy

2.3.  Operational state overview

   The BGP operational model contains data which relates to the
   operational state of the various elements of the BGP router.  As
   noted in Section 2 - the approach described in
   [I-D.openconfig-netmod-opstate] is utilized for the inclusion of
   operational and statistical data.  To this end, the "-state"
   groupings (those that contain derived operational parameters) are
   contained within the BGP operational model - and included within the
   relevant "state" containers throughout the core BGP model.  In some
   cases, operational information may be relevant to one instance of a
   common grouping, but not another - for example, the number of
   received, advertised, and installed prefixes is relevant on a per-
   neighbor-basis, but is not required (or meaningful) in the peer-group
   context.  Groupings are defined with the appropriate operational
   state data accordingly.

3.  Relation to other YANG data models

   The BGP model is intended to work within a larger framework model,
   such as the Network Instance model
   [I-D.openconfig-rtgwg-network-instance] YANG Model for Network Instance
   [I-D.ietf-rtgwg-ni-model] which provides a comprehensive model for
   defining VRFs, associated routing protocols, multiple protocol
   instances, and inter-protocol and inter-instance routing policies.
   The current version of the model imports and instantiates the BGP
   model in its tree at /network-instances/network-
   instance/protocols/protocol/bgp/... /network-instances/network-instance/vrf-
   root/rt:routing/control-plane-protocols/control-plane-protocol/
   bgp/...

   It is also possible to integrate the BGP model with the Routing
   Management model [I-D.ietf-netmod-routing-cfg] or the Network Device
   Organizational A YANG Data Model [I-D.rtgyangdt-rtgwg-device-model], both of for Routing Management [RFC8349]
   which define defines the notion of routing instances, or VRFs.

4.  Security Considerations

   BGP configuration has a significant impact on network operations, and
   as such any related protocol or model carries potential security
   risks.

   The YANG module specified in this document defines a schema for data models are generally
   that is designed to be used with the accessed via network management protocols such
   as NETCONF
   protocol over an SSH transport.  This provides an authenticated and [RFC6241] or RESTCONF [RFC8040].  The lowest NETCONF layer
   is the secure channel over which to transfer BGP configuration transport layer, and
   operational data.  Note that use of alternate the mandatory-to-implement secure
   transport or data
   encoding (e.g., JSON over HTTPS) would require similar mechanisms for
   authenticating is Secure Shell (SSH) [RFC6242].  The lowest RESTCONF layer
   is HTTPS, and securing the mandatory-to-implement secure transport is TLS
   [RFC5246].  The NETCONF Access Control Model (NACM) [RFC8341]
   provides the means to restrict access for particular NETCONF or
   RESTCONF users to configuration data.

   Most a preconfigured subset of the data elements all available NETCONF or
   RESTCONF protocol operations and content.

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

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

   Some of the RPC operations in this YANG module may be considered
   sensitive or vulnerable in some network environments.  It is thus
   important to control access to these operations.  These are the
   operations and their sensitivity/vulnerability:

5.  IANA Considerations

   An appropriate namespace

   This document registers three URIs and three YANG modules.

5.1.  URI will be registered Registration

   in the IETF XML
   Registry" registry [RFC3688] [RFC3688].  Following the format
   in RFC 3688, the following registration is requested to be made:

   URI: urn:ietf:params:xml:ns:yang:ietf-bgp
   URI: urn:ietf:params:xml:ns:yang:ietf-bgp-policy
   URI: urn:ietf:params:xml:ns:yang:ietf-bgp-types

   Registrant Contact: The BGP IESG.  XML: N/A, the requested URI is an XML
   namespace.

5.2.  YANG modules will be registered Module Name Registration

   This document registers three YANG module in the
   "YANG YANG Module Names" Names
   registry YANG [RFC6020].

   name: ietf-bgp
   namespace: urn:ietf:params:xml:ns:yang:ietf-bgp
   prefix: bgp
   reference: RFC XXXX

   name: ietf-bgp-policy
   namespace: urn:ietf:params:xml:ns:yang:ietf-bgp-policy
   prefix: bgp-pol
   reference: RFC XXXX

   name: ietf-bgp-types
   namespace: urn:ietf:params:xml:ns:yang:ietf-bgp-types
   prefix: bgp-types
   reference: RFC XXXX

6.  YANG modules

   The modules comprising the BGP configuration and operational model
   are described by the YANG modules and submodules in the sections
   below.

   The main module, openconfig-bgp.yang, ietf-bgp.yang, includes the following submodules:

   o  openconfig-bgp-common  ietf-bgp-common - defines the groupings that are common across
      more than one context (where contexts are neighbor, group, global)

   o  openconfig-bgp-common-multiprotocol  ietf-bgp-common-multiprotocol - defines the groupings that are
      common across more than one context, and relate to multiprotocol
      BGP

   o  openconfig-bgp-common-structure  ietf-bgp-common-structure - defines groupings that are shared by
      multiple contexts, but are used only to create structural
      elements, i.e., containers (leaf nodes are defined in separate
      groupings)

   o  openconfig-bgp-global  ietf-bgp-global - groupings with data specific to the global
      context

   o  openconfig-bgp-peer-group  ietf-bgp-peer-group - groupings with data specific to the peer
      group context

   o  openconfig-bgp-neighbor  ietf-bgp-neighbor - groupings with data specific to the neighbor
      context

   Additional modules include:

   o  openconfig-bgp-types  ietf-bgp-types - common type and identity definitions for BGP,
      including BGP policy

   o  openconfig-bgp-policy  ietf-bgp-policy - BGP-specific policy data definitions for use
      with [I-D.ietf-rtgwg-policy-model] (described in more detail
      Section 2.2)

7.  BGP main module and submodule for base items

  <CODE BEGINS> file "ietf-bgp.yang" "ietf-bgp@2018-05-09.yang"
  module ietf-bgp {
    yang-version "1";
  // namespace "1.1";
    namespace "urn:ietf:params:xml:ns:yang:ietf-bgp";
    prefix "bgp";

  // import some basic inet types
  import openconfig-extensions { prefix oc-ext; }

    import ietf-routing-policy {
      prefix rpol;
      reference
        "RFC ZZZZ: A YANG Data Model for Routing Policy Management";
    }

  // Include the OpenConfig BGP submodules
  // Common: defines the groupings that are common across more than
  //         one context (where contexts are neighbor, group, global)

    include ietf-bgp-common;
  // Multiprotocol: defines the groupings that are common across more
  //                than one context, and relate to Multiprotocol
    include ietf-bgp-common-multiprotocol;
  // Structure: defines groupings that are shared but are solely used for
  //            structural reasons.
    include ietf-bgp-common-structure;
  // Include peer-group/neighbor/global - these define the groupings
  // that are specific to one context
  include ietf-bgp-peer-group;
    include ietf-bgp-neighbor;
    include ietf-bgp-global;

  // meta
    include ietf-bgp-peer-group;

    organization
    "OpenConfig working group";
      "IETF IDR Working Group";

    contact
    "OpenConfig working group
    netopenconfig@googlegroups.com";
      "WG Web:   <http://tools.ietf.org/wg/idr>
       WG List:  <idr@ietf.org>

       Authors: Keyur Patel (keyur at arrcus.com),
                Mahesh Jethanandani (mjethanandani at gmail.com),
                Susan Hares (shares at ndzh.com";

    description
      "This module describes a YANG model for BGP protocol
    configuration.It
       configuration. It is a limited subset of all of the configuration
       parameters available in the variety of vendor implementations,
       hence it is expected that it would be augmented with vendor-
       specific configuration data as needed. Additional modules or
       submodules to handle other aspects of BGP configuration,
       including policy, VRFs, VPNs, and additional address families
       are also expected.

       This model supports the following BGP configuration level
       hierarchy:

        BGP
          |
          +-> [ global BGP configuration ]
            +-> AFI / SAFI global
          +-> peer group
            +-> [ peer group config ]
            +-> AFI / SAFI [ per-AFI overrides ]
          +-> neighbor
            +-> [ neighbor config ]
            +-> [ optional pointer to peer-group ]
            +-> AFI / SAFI [ per-AFI overrides ]";

  oc-ext:openconfig-version "2.1.1";

  revision "2016-06-21" {
    description
      "OpenConfig BGP refactor";
    reference "2.1.1";
  }

  revision "2016-06-06" {
    description
      "OpenConfig public release";
    reference "2.1.0";
  }

    revision "2016-03-31" "2018-05-09" {
      description
      "OpenConfig public release";
        "Initial Version";
      reference "2.0.1";
  }

  grouping bgp-top {
    description
      "Top-level grouping for the
        "RFC XXXX, BGP model data"; Model for Service Provider Network ";
    }

    /*
     * Groupings
     */
    container bgp {
      description
        "Top-level configuration and state for the BGP router";

      container global {
        presence "Enables global configuration of BGP";
        description
          "Global configuration for the BGP router";
        uses bgp-global-base;
        uses rpol:apply-policy-group;
      }

      container neighbors {
        description
          "Configuration for BGP neighbors";
        uses bgp-neighbor-list;
      }

      container peer-groups {
        description
          "Configuration for BGP peer-groups";
        uses bgp-peer-group-list;
      }
    }
  }

  uses bgp-top;

}
  <CODE ENDS>
  <CODE BEGINS> file "ietf-bgp-common.yang" "ietf-bgp-common@2018-05-09.yang"
  submodule ietf-bgp-common {
    yang-version "1.1";
    belongs-to ietf-bgp {
      prefix "bgp";
    }

    import openconfig-extensions { prefix oc-ext; }
     import ietf-bgp-types {
      prefix oc-bgp-types; }
     import ietf-routing-policy { prefix rpol; bgp-types;
    }
    import ietf-inet-types {
      prefix inet;
    }

     // meta

    organization
       "OpenConfig working group";
      "IETF IDR Working Group";

    contact
       "OpenConfig working group
       netopenconfig@googlegroups.com";
      "WG Web:   <http://tools.ietf.org/wg/idr>
       WG List:  <idr@ietf.org>

       Authors: Keyur Patel,
                Mahesh Jethanandani,
                Susan Hares";

    description
      "This sub-module contains common groupings that are common across
       multiple contexts within the BGP module. That is to say that
       they may be application to a subset of global, peer-group or
       neighbor contexts.";

     oc-ext:openconfig-version "2.1.1";

    revision "2016-06-21" "2018-05-09" {
      description
         "OpenConfig BGP refactor";
        "Initial Version";
      reference "2.1.1";
        "RFC XXX, BGP Model for Service Provider Network.";
    }

    grouping bgp-common-neighbor-group-timers-config {
      description
        "Config parameters related to timers associated with the BGP
         peer";

      leaf connect-retry {
        type decimal64 {
          fraction-digits 2;
        }
        default 30;
        description
          "Time interval in seconds between attempts to establish a
           session with the peer.";
      }

      leaf hold-time {
        type decimal64 {
          fraction-digits 2;
        }
        default 90;
        description
          "Time interval in seconds that a BGP session will be
           considered active in the absence of keepalive or other
           messages from the peer.  The hold-time is typically set to
           3x the keepalive-interval.";
        reference
          "RFC 4271 - A Border Gateway Protocol 4, Sec. 10";
      }

      leaf keepalive-interval {
        type decimal64 {
          fraction-digits 2;
        }
        default 30;
        description
          "Time interval in seconds between transmission of keepalive
           messages to the neighbor.  Typically set to 1/3 the
           hold-time.";
      }

      leaf minimum-advertisement-interval {
        type decimal64 {
          fraction-digits 2;
        }
        default 30;
        description
          "Minimum time which must elapse between subsequent UPDATE
           messages relating to a common set of NLRI being transmitted
           to a peer. This timer is referred to as
           MinRouteAdvertisementIntervalTimer by RFC 4721 and serves to
           reduce the number of UPDATE messages transmitted when a
           particular set of NLRI exhibit instability.";
        reference
          "RFC 4271 - A Border Gateway Protocol 4, Sec 9.2.1.1";
      }
    }

    grouping bgp-common-neighbor-group-config {
      description
        "Neighbor level configuration items.";

      leaf peer-as {
        type inet:as-number;
        description
          "AS number of the peer.";
      }

      leaf local-as {
        type inet:as-number;
        description
          "The local autonomous system number that is to be used when
           establishing sessions with the remote peer or peer group, if
           this differs from the global BGP router autonomous system
           number.";
      }

      leaf peer-type {
          type oc-bgp-types:peer-type; bgp-types:peer-type;
          description
            "Explicitly designate the peer or peer group as internal
             (iBGP) or external (eBGP).";
      }

      leaf auth-password {
        type string;
        description
          "Configures an MD5 authentication password for use with
           neighboring devices.";
      }

      leaf remove-private-as {
        // could also make this a container with a flag to enable
        // remove-private and separate option.  here, option implies
        // remove-private is enabled.
        type oc-bgp-types:remove-private-as-option; bgp-types:remove-private-as-option;
        description
          "Remove private AS numbers from updates sent to peers - when
           this leaf is not specified, the AS_PATH attribute should be
           sent to the peer unchanged";
      }

      leaf route-flap-damping {
        type boolean;
        default false;
        description
          "Enable route flap damping.";

      }

      leaf send-community {
        type oc-bgp-types:community-type; bgp-types:community-type;
        default "NONE";
        description
          "Specify which types of community should be sent to the
           neighbor or group. The default is to not send the community
           attribute";
      }

      leaf description {
        type string;
        description
          "An optional textual description (intended primarily for use
           with a peer or group";
      }
    }

    grouping bgp-common-neighbor-group-transport-config {
      description
        "Configuration parameters relating to the transport protocol
         used by the BGP session to the peer";

      leaf tcp-mss {
        type uint16;
        description
          "Sets the max segment size for BGP TCP sessions.";
      }

      leaf mtu-discovery {
        type boolean;
        default false;
        description
          "Turns path mtu discovery for BGP TCP sessions on (true) or
           off (false)";
      }

      leaf passive-mode {
        type boolean;
        default false;
        description
          "Wait for peers to issue requests to open a BGP session,
           rather than initiating sessions from the local router.";
      }

      leaf local-address {
        type union {
          type inet:ip-address;
          type string;
        }
        //TODO:  the string should be converted to a leafref type
        //to point to an interface when YANG 1.1 is available with
        //leafrefs in union types.
        description
          "Set the local IP (either IPv4 or IPv6) address to use for
           the session when sending BGP update messages.  This may be
           expressed as either an IP address or reference to the name
           of an interface.";
      }
    }

    grouping bgp-common-neighbor-group-error-handling-config {
      description
        "Configuration parameters relating to enhanced error handling
         behaviours for BGP";

      leaf treat-as-withdraw {
        type boolean;
        default "false";
        description
          "Specify whether erroneous UPDATE messages for which the NLRI
           can be extracted are reated as though the NLRI is withdrawn
           - avoiding session reset";
        reference "draft-ietf-idr-error-handling-16";
      }
    }

    grouping bgp-common-neighbor-group-logging-options-config bgp-common-graceful-restart-config {
      description
        "Configuration parameters specifying the logging behaviour for
         BGP sessions to the peer";

       leaf log-neighbor-state-changes {
         type boolean;
         default "true";
         description
           "Configure logging of peer state changes.  Default is relating to enable logging of peer state changes.";
       }
     }

     grouping bgp-common-neighbor-group-multihop-config {
       description
         "Configuration parameters specifying the multihop behaviour for BGP sessions to the peer"; graceful restart.";

      leaf enabled {
        type boolean;
         default "false";
        description
           "When enabled the referenced group
          "Enable or neighbors are permitted
           to be indirectly connected - including cases where the TTL
           can be decremented between disable the BGP peers"; graceful-restart capability.";
      }

      leaf multihop-ttl restart-time {
        type uint8; uint16 {
          range 0..4096;
        }
        description
           "Time-to-live value to use when packets are sent
          "Estimated time (in seconds) for the local BGP speaker to
           restart a session. This value is advertise in the
           referenced group or neighbors and ebgp-multihop graceful
           restart BGP capability.  This is enabled";
       }
     }

     grouping bgp-common-neighbor-group-route-reflector-config {
       description
         "Configuration parameters determining whether a 12-bit value, referred to
           as Restart Time in RFC4724.  Per RFC4724, the behaviour of suggested
           default value is <= the local system when acting as a route-reflector"; hold-time value.";
      }

      leaf route-reflector-cluster-id stale-routes-time {
        type oc-bgp-types:rr-cluster-id-type; decimal64 {
          fraction-digits 2;
        }
        description
           "route-reflector cluster id to use when local router is
           configured as a route reflector.  Commonly set at
          "An upper-bound on the group
           level, but allows time that stale routes will be
           retained by a different cluster
           id router after a session is restarted. If an
           End-of-RIB (EOR) marker is received prior to this timer
           expiring stale-routes will be set for each neighbor."; flushed upon its receipt - if
           no EOR is received, then when this timer expires stale paths
           will be purged. This timer is referred to as the
           Selection_Deferral_Timer in RFC4724";
      }

      leaf route-reflector-client helper-only {
        type boolean;
         default "false";
        description
           "Configure
          "Enable graceful-restart in helper mode only. When this leaf
           is set, the neighbor as local system does not retain forwarding its own
           state during a route reflector client."; restart, but supports procedures for the
           receiving speaker, as defined in RFC4724.";
      }
    }

    grouping bgp-common-neighbor-group-as-path-options-config bgp-common-use-multiple-paths-config {
      description
         "Configuration parameters allowing manipulation
        "Generic configuration options relating to use of the AS_PATH
         attribute"; multiple
         paths for a referenced AFI-SAFI, group or neighbor";

      leaf allow-own-as enabled {
        type uint8; boolean;
        default 0; false;
        description
           "Specify
          "Whether the number of occurrences use of multiple paths for the local BGP speaker's
           AS that can occur within the AS_PATH before it same NLRI is rejected.";
       }

       leaf replace-peer-as {
         type boolean;
         default "false";
         description
           "Replace occurrences of the peer's AS in the AS_PATH
           with
           enabled for the local autonomous system number"; neighbor. This value is overridden by any
           more specific configuration value.";
      }
    }

    grouping bgp-common-neighbor-group-add-paths-config bgp-common-use-multiple-paths-ebgp-as-options-config {
      description
        "Configuration parameters specfying whether the local system
         will send or receive multiple paths using ADD_PATHS"; specific to eBGP multi-path applicable
         to all contexts";

      leaf receive allow-multiple-as {
       type boolean;
       default false; "false";
       description
           "Enable ability
        "Allow multi-path to receive multiple path advertisements
           for an NLRI use paths from the neighbor or group";
       }

       leaf send-max different neighboring ASes.
         The default is to only consider multiple paths from the same
         neighboring AS.";
      }
    }

    grouping bgp-common-global-group-use-multiple-paths {
      description
        "Common grouping used for both global and groups which provides
         configuration and state parameters relating to use of multiple
         paths";

      container use-multiple-paths {
        description
          "Parameters related to the use of multiple paths for the
          same NLRI";

        uses bgp-common-use-multiple-paths-config;

        container ebgp {
          description
            "Multi-Path parameters for eBGP";

          leaf allow-multiple-as {
            type uint8; boolean;
            default "false";
            description
           "The maximum
              "Allow multi-path to use paths from different neighboring
               ASes.  The default is to only consider multiple paths
               from the same neighboring AS.";
          }

          leaf maximum-paths {
            type uint32;
            default 1;
            description
              "Maximum number of parallel paths to advertise to neighbors
           for consider when using
               BGP multi-path. The default is use a single NLRI"; path.";
          }
        }

        container ibgp {
          description
            "Multi-Path parameters for iBGP";

          leaf eligible-prefix-policy maximum-paths {
            type leafref {
           path "/rpol:routing-policy/rpol:policy-definitions/" +
             "rpol:policy-definition/rpol:name";
         } uint32;
            default 1;
            description
           "A reference to a routing policy which can be used
              "Maximum number of parallel paths to
           restrict the prefixes for which add-paths consider when using
               iBGP multi-path. The default is enabled"; to use a single path";
          }
        }
      }
    }

    grouping bgp-common-graceful-restart-config bgp-common-route-selection-options {
      description
        "Configuration parameters and state relating to BGP graceful restart."; route selection options";

      container route-selection-options {
        description
          "Parameters relating to options for route selection";

        leaf enabled always-compare-med {
          type boolean;
          default "false";
          description
           "Enable or disable
            "Compare multi-exit discriminator (MED) value from
             different ASes when selecting the graceful-restart capability."; best route.  The default
             behavior is to only compare MEDs for paths received from
             the same AS.";
        }

        leaf restart-time ignore-as-path-length {
          type uint16 {
           range 0..4096;
         } boolean;
          default "false";
          description
           "Estimated time (in seconds) for
            "Ignore the local BGP speaker to
           restart a session. This value is advertise in AS path length when selecting the graceful
           restart BGP capability.  This best path.
             The default is a 12-bit value, referred to
           as Restart Time in RFC4724.  Per RFC4724, use the suggested AS path length and prefer paths
             with shorter length.";
        }

        leaf external-compare-router-id {
          type boolean;
          default value is <= "true";
          description
            "When comparing similar routes received from external BGP
             peers, use the hold-time value."; router-id as a criterion to select the
             active path.";
        }

        leaf stale-routes-time advertise-inactive-routes {
          type decimal64 {
           fraction-digits 2;
         } boolean;
          default "false";
          description
           "An upper-bound on the time thate stale
            "Advertise inactive routes will be
           retained by a router after a session is restarted. If an
           End-of-RIB (EOR) marker is received prior to this timer
           expiring stale-routes will be flushed upon its receipt - if
           no EOR is received, then when this timer expires stale paths
           will be purged. This timer external peers.  The default
             is referred to as the
           Selection_Deferral_Timer in RFC4724"; only advertise active routes.";
        }

        leaf helper-only enable-aigp {
          type boolean;
          default false;
          description
           "Enable graceful-restart
            "Flag to enable sending / receiving accumulated IGP
             attribute in helper mode only. When this routing updates";
        }

        leaf ignore-next-hop-igp-metric {
          type boolean;
          default "false";
          description
            "Ignore the IGP metric to the next-hop when calculating BGP
             best-path. The default is set, to select the local system does not retain forwarding
           its own state during a restart, but supports procedures route for which
             the receiving speaker, as defined in RFC4724."; metric to the next-hop is lowest";
        }
      }
    }

    grouping bgp-common-use-multiple-paths-config bgp-common-state {
      description
         "Generic configuration options
        "Grouping containing common counters relating to use of multiple
         paths for a referenced AFI-SAFI, group or neighbor"; prefixes and
         paths";

      leaf enabled total-paths {
        type boolean;
         default uint32;
        config false;
        description
           "Whether the use
          "Total number of multiple BGP paths for the same NLRI is
           enabled for within the neighbor. This value is overridden by
           any more specific configuration value.";
       } context";
      }

     grouping bgp-common-use-multiple-paths-ebgp-as-options-config {
       description
         "Configuration parameters specific to eBGP multipath applicable
         to all contexts";

      leaf allow-multiple-as total-prefixes {
        type boolean;
        default "false"; uint32;
        config false;
        description
         "Allow multipath to use paths from different neighbouring
         ASes.  The default is to only consider multiple paths from
          "Total number of BGP prefixes received within the same neighbouring AS."; context";
      }
    }

     grouping bgp-common-global-group-use-multiple-paths
  }
  <CODE ENDS>
   <CODE BEGINS> file "ietf-bgp-common-multiprotocol@2018-05-09.yang"
   submodule ietf-bgp-common-multiprotocol {
       description
         "Common grouping used for both global and groups which provides
         configuration and state parameters relating to use of multiple
         paths";

       container use-multiple-paths
     yang-version "1.1";
     belongs-to ietf-bgp {
       prefix "bgp";
     }

     import ietf-bgp-types {
       prefix bgp-types;
     }
     import ietf-routing-policy {
       prefix rpol;
     }

     include ietf-bgp-common;

     // meta
     organization
       "IETF IDR Working Group";

     contact
       "WG Web:   <http://tools.ietf.org/wg/idr>
        WG List:  <idr@ietf.org>

        Editor:  Mahesh Jethanandani (mjethanandani@gmail.com)
        Authors: Keyur Patel,
                 Mahesh Jethanandani,
                 Susan Hares";

     description
           "Parameters
       "This sub-module contains groupings that are related to the use of support
        for multiple paths protocols in BGP. The groupings are common across
        multiple contexts.";

     revision "2018-05-09" {
       description
         "Initial Version";
       reference
         "RFC XXX, BGP Model for the
           same NLRI";

         container config Service Provider Network.";
     }

     grouping bgp-common-mp-afi-safi-graceful-restart-config {
       description
             "Configuration
         "BGP graceful restart parameters relating to multipath";
           uses bgp-common-use-multiple-paths-config;
         }
         container state that apply on a per-AFI-SAFI
         basis";

       leaf enabled {
           config
         type boolean;
         default false;
         description
             "State parameters relating to multipath";
           uses bgp-common-use-multiple-paths-config;
           "This leaf indicates whether graceful-restart is enabled for
           this AFI-SAFI";
       }

         container ebgp
     }

     grouping bgp-common-mp-afi-safi-config {
       description
             "Multipath
         "Configuration parameters used for eBGP";
           container config all BGP AFI-SAFIs";

       leaf afi-safi-name {
         type identityref {
           base bgp-types:AFI_SAFI_TYPE;
         }
         description
               "Configuration parameters relating to eBGP multipath";
             uses bgp-common-use-multiple-paths-ebgp-config; "AFI,SAFI";
       }
           container state

       leaf enabled {
             config
         type boolean;
         default false;
         description
               "State information relating to eBGP multipath";
             uses bgp-common-use-multiple-paths-ebgp-config;
           "This leaf indicates whether the IPv4 Unicast AFI,SAFI is
           enabled for the neighbour or group";
       }
     }

         container ibgp

     grouping bgp-common-mp-all-afi-safi-list-contents {
       description
             "Multipath parameters
         "A common grouping used for iBGP";
           container config {
             description
               "Configuration parameters relating to iBGP multipath"; contents of the list that is used
         for AFI-SAFI entries";

       // import and export policy included for the afi/safi
       uses rpol:apply-policy-group;

       uses bgp-common-mp-ipv4-unicast-group;
       uses bgp-common-mp-ipv6-unicast-group;
       uses bgp-common-mp-ipv4-labeled-unicast-group;
       uses bgp-common-mp-ipv6-labeled-unicast-group;
       uses bgp-common-mp-l3vpn-ipv4-unicast-group;
       uses bgp-common-mp-l3vpn-ipv6-unicast-group;
       uses bgp-common-mp-l3vpn-ipv4-multicast-group;
       uses bgp-common-mp-l3vpn-ipv6-multicast-group;
       uses bgp-common-mp-l2vpn-vpls-group;
       uses bgp-common-use-multiple-paths-ibgp-config; bgp-common-mp-l2vpn-evpn-group;
     }
           container state {
             config false;
             description
               "State information

     // Groupings relating to iBGP multipath";
             uses bgp-common-use-multiple-paths-ibgp-config;
           }
         }
       }
     } each address family
     grouping bgp-common-use-multiple-paths-ebgp-config bgp-common-mp-ipv4-unicast-group {
       description
         "Configuration parameters relating to multipath
         "Group for eBGP";

       leaf allow-multiple-as IPv4 Unicast configuration options";

       container ipv4-unicast {
         when "../afi-safi-name = 'bgp-types:IPV4_UNICAST'" {
        type boolean;
        default "false";
           description
         "Allow multipath to use paths from different neighbouring
         ASes.  The default is to only consider multiple paths from
         the same neighbouring AS.";
             "Include this container for IPv4 Unicast specific
             configuration";
         }

       leaf maximum-paths {
        type uint32;
        default 1;

         description
         "Maximum number of parallel paths to consider when using
         BGP multipath. The default is use a single path."; "IPv4 unicast configuration options";

         // include common IPv[46] unicast options
         uses bgp-common-mp-ipv4-ipv6-unicast-common;

         // placeholder for IPv4 unicast  specific configuration
       }
     }

     grouping bgp-common-use-multiple-paths-ibgp-config bgp-common-mp-ipv6-unicast-group {
       description
         "Configuration parmaeters relating to multipath
         "Group for iBGP";

       leaf maximum-paths IPv6 Unicast configuration options";

       container ipv6-unicast {
         type uint32;
         default 1;
         description
           "Maximum number of parallel paths to consider
         when using
           iBGP multipath. The default is to use a single path";
       }
     }

     grouping bgp-common-route-selection-options-config "../afi-safi-name = 'bgp-types:IPV6_UNICAST'" {
           description
         "Set of
             "Include this container for IPv6 Unicast specific
             configuration";
         }

         description "IPv6 unicast configuration options";

         // include common IPv[46] unicast options that govern best
          path selection.";

       leaf always-compare-med {
         type boolean;
         default "false";
         description
           "Compare multi-exit discriminator (MED) value from
           different ASes when selecting the best route.  The
           default behavior is to only compare MEDs for paths
           received from the same AS.";

       }

       leaf ignore-as-path-length {
         type boolean;
         default "false";
         description
           "Ignore the AS path length when selecting the best path.
           The default is to use the AS path length and prefer paths
           with shorter length.";
       }

       leaf external-compare-router-id {
         type boolean;
         default "true";
         description
           "When comparing similar routes received from external
           BGP peers, use the router-id as a criterion to select
           the active path.";
       }

       leaf advertise-inactive-routes {
         type boolean;
         default "false";
         description
           "Advertise inactive routes to external peers.  The
           default is to only advertise active routes.";
       }

       leaf enable-aigp {
         type boolean;
         default false;
         description
           "Flag to enable sending / receiving accumulated IGP
           attribute in routing updates";
       }

       leaf ignore-next-hop-igp-metric {
         type boolean;
         default "false";
         description
           "Ignore the IGP metric to the next-hop when calculating
           BGP best-path. The default is to select the route for
           which the metric to the next-hop is lowest";
       }
     }

     grouping bgp-common-route-selection-options {
       description
         "Configuration and state relating to route selection options";

       container route-selection-options {
         description
           "Parameters relating to options for route selection";
         container config {
           description
             "Configuration parameters relating to route selection
             options";
           uses bgp-common-route-selection-options-config;
         }
         container state {
           config false;
           description
             "State information for the route selection options";
           uses bgp-common-route-selection-options-config;
         }
       }
     }

     grouping bgp-common-state {
       description
         "Grouping containing common counters relating to prefixes and
         paths";

       leaf total-paths {
         type uint32;
         description
           "Total number of BGP paths within the context";
       }

       leaf total-prefixes {
         type uint32;
         description
           "Total number of BGP prefixes received within the context";
       }
     }

   }

   <CODE ENDS>

   <CODE BEGINS> file "ietf-bgp-common-multiprotocol.yang"

   submodule ietf-bgp-common-multiprotocol {
     belongs-to ietf-bgp {
       prefix "bgp";
     }

     import openconfig-extensions { prefix oc-ext; }
     import ietf-bgp-types { prefix oc-bgp-types; }
     import ietf-routing-policy { prefix rpol; }
     import openconfig-types { prefix oc-types; }

     include ietf-bgp-common;

     // meta
     organization
       "OpenConfig working group";

     contact
       "OpenConfig working group
       netopenconfig@googlegroups.com";

     description
       "This sub-module contains groupings that are related to support
       for multiple protocols in BGP. The groupings are common across
       multiple contexts.";

     oc-ext:openconfig-version "2.1.1";

     revision "2016-06-21" {
       description
         "OpenConfig BGP refactor";
       reference "2.1.1";
     }

     grouping bgp-common-mp-afi-safi-graceful-restart-config {
       description
         "BGP graceful restart parameters that apply on a per-AFI-SAFI
         basis";

       leaf enabled {
         type boolean;
         default false;
         description
           "This leaf indicates whether graceful-restart is enabled for
           this AFI-SAFI";
       }
     }

     grouping bgp-common-mp-afi-safi-config {
       description
         "Configuration parameters used for all BGP AFI-SAFIs";

       leaf afi-safi-name {
         type identityref {
           base oc-bgp-types:AFI_SAFI_TYPE;
         }
         description "AFI,SAFI";
       }

       leaf enabled {
         type boolean;
         default false;
         description
           "This leaf indicates whether the IPv4 Unicast AFI,SAFI is
           enabled for the neighbour or group";
       }
     }

     grouping bgp-common-mp-all-afi-safi-list-contents {
       description
         "A common grouping used for contents of the list that is used
         for AFI-SAFI entries";

       // import and export policy included for the afi/safi
       uses rpol:apply-policy-group;

       uses bgp-common-mp-ipv4-unicast-group;
       uses bgp-common-mp-ipv6-unicast-group;
       uses bgp-common-mp-ipv4-labeled-unicast-group;
       uses bgp-common-mp-ipv6-labeled-unicast-group;
       uses bgp-common-mp-l3vpn-ipv4-unicast-group;
       uses bgp-common-mp-l3vpn-ipv6-unicast-group;
       uses bgp-common-mp-l3vpn-ipv4-multicast-group;
       uses bgp-common-mp-l3vpn-ipv6-multicast-group;
       uses bgp-common-mp-l2vpn-vpls-group;
       uses bgp-common-mp-l2vpn-evpn-group;
     }

     // Groupings relating to each address family
     grouping bgp-common-mp-ipv4-unicast-group {
       description
         "Group for IPv4 Unicast configuration options";

       container ipv4-unicast {
         when "../afi-safi-name = 'oc-bgp-types:IPV4_UNICAST'" {
           description
             "Include this container for IPv4 Unicast specific
             configuration";

         }

         description "IPv4 unicast configuration options";

         // include common IPv[46] unicast options
         uses bgp-common-mp-ipv4-ipv6-unicast-common;

         // placeholder for IPv4 unicast  specific configuration
       }
     }

     grouping bgp-common-mp-ipv6-unicast-group {
       description
         "Group for IPv6 Unicast configuration options";

       container ipv6-unicast {
         when "../afi-safi-name = 'oc-bgp-types:IPV6_UNICAST'" {
           description
             "Include this container for IPv6 Unicast specific
             configuration";
         }

         description "IPv6 unicast configuration options";

         // include common IPv[46] unicast options
         uses bgp-common-mp-ipv4-ipv6-unicast-common;

         // placeholder for IPv6 unicast specific configuration
         // options
       }
     }

     grouping bgp-common-mp-ipv4-labeled-unicast-group {
       description
         "Group for IPv4 Labeled Unicast configuration options";

       container ipv4-labeled-unicast {
         when "../afi-safi-name = 'oc-bgp-types:IPV4_LABELED_UNICAST'" {
           description
             "Include this container for IPv4 Labeled Unicast specific
             configuration";
         }

         description "IPv4 Labeled Unicast configuration options";

         uses bgp-common-mp-all-afi-safi-common;

         // placeholder for IPv4 Labeled Unicast specific config
         // options
       }
     }

     grouping bgp-common-mp-ipv6-labeled-unicast-group {
       description
         "Group for IPv6 Labeled Unicast configuration options";

       container ipv6-labeled-unicast {
         when "../afi-safi-name = 'oc-bgp-types:IPV6_LABELED_UNICAST'" {
           description
             "Include this container for IPv6 Labeled Unicast specific
             configuration";
         }

         description "IPv6 Labeled Unicast configuration options";

         uses bgp-common-mp-all-afi-safi-common;

         // placeholder for IPv6 Labeled Unicast specific config
         // options.
       }
     }

     grouping bgp-common-mp-l3vpn-ipv4-unicast-group {
       description
         "Group for IPv4 Unicast L3VPN configuration options";

       container l3vpn-ipv4-unicast {
         when "../afi-safi-name = 'oc-bgp-types:L3VPN_IPV4_UNICAST'" {
           description
             "Include this container for IPv4 Unicast L3VPN specific
             configuration";
         }

         description "Unicast IPv4 L3VPN configuration options";

         // include common L3VPN configuration options
         uses bgp-common-mp-l3vpn-ipv4-ipv6-unicast-common;

         // placeholder for IPv4 Unicast L3VPN specific config options.
       }
     }

     grouping bgp-common-mp-l3vpn-ipv6-unicast-group {
       description
         "Group for IPv6 Unicast L3VPN configuration options";

       container l3vpn-ipv6-unicast {
         when "../afi-safi-name = 'oc-bgp-types:L3VPN_IPV6_UNICAST'" {
           description
             "Include this container for unicast IPv6 L3VPN specific
             configuration";
         }

         description "Unicast IPv6 L3VPN configuration options";

         // include common L3VPN configuration options
         uses bgp-common-mp-l3vpn-ipv4-ipv6-unicast-common;

         // placeholder for IPv6 Unicast L3VPN specific configuration
         // options
       }
     }

     grouping bgp-common-mp-l3vpn-ipv4-multicast-group {
       description
         "Group for IPv4 L3VPN multicast configuration options";

       container l3vpn-ipv4-multicast {
         when "../afi-safi-name = 'oc-bgp-types:L3VPN_IPV4_MULTICAST'" {
           description
             "Include this container for multicast IPv6 L3VPN specific
             configuration";
         }

         description "Multicast IPv4 L3VPN configuration options";

         // include common L3VPN multicast options
         uses bgp-common-mp-l3vpn-ipv4-ipv6-multicast-common;

         // placeholder for IPv4 Multicast L3VPN specific configuration
         // options
       }
     }

     grouping bgp-common-mp-l3vpn-ipv6-multicast-group {
       description
         "Group for IPv6 L3VPN multicast configuration options";

       container l3vpn-ipv6-multicast {
         when "../afi-safi-name = 'oc-bgp-types:L3VPN_IPV6_MULTICAST'" {
           description
             "Include this container for multicast IPv6 L3VPN specific
             configuration";
         }
         description "Multicast IPv6 L3VPN configuration options";

         // include common L3VPN multicast options
         uses bgp-common-mp-l3vpn-ipv4-ipv6-multicast-common;

         // placeholder for IPv6 Multicast L3VPN specific configuration
         // options
       }
     }

     grouping bgp-common-mp-l2vpn-vpls-group {
       description
         "Group for BGP-signalled VPLS configuration options";

       container l2vpn-vpls {
         when "../afi-safi-name = 'oc-bgp-types:L2VPN_VPLS'" {
           description
             "Include this container for BGP-signalled VPLS specific
             configuration";
         }

         description "BGP-signalled VPLS configuration options";

         // include common L2VPN options
         uses bgp-common-mp-l2vpn-common;

         // placeholder for BGP-signalled VPLS specific configuration
         // options
       }
     }

     grouping bgp-common-mp-l2vpn-evpn-group {
       description
         "Group for BGP EVPN configuration options";

       container l2vpn-evpn {
         when "../afi-safi-name = 'oc-bgp-types:L2VPN_EVPN'" {
           description
             "Include this container for BGP EVPN specific
             configuration";
         }

         description "BGP EVPN configuration options";

         // include common L2VPN options
         uses bgp-common-mp-l2vpn-common;

         // placeholder for BGP EVPN specific configuration options

       }
     }

     // Common groupings across multiple AFI,SAFIs
     grouping bgp-common-mp-all-afi-safi-common {
       description
         "Grouping for configuration common to all AFI,SAFI";

       container prefix-limit {
         description
           "Configure the maximum number of prefixes that will be
           accepted from a peer";

         container config {
           description
             "Configuration parameters relating to the prefix
             limit for the AFI-SAFI";
           uses bgp-common-mp-all-afi-safi-common-prefix-limit-config;
         }

         container state {
           config false;
           description
             "State information relating to the prefix-limit for the
             AFI-SAFI";
           uses bgp-common-mp-all-afi-safi-common-prefix-limit-config;
         }
       }
     }

     grouping bgp-common-mp-ipv4-ipv6-unicast-common {
       description
         "Common configuration that is applicable for IPv4 and IPv6
         unicast";

       // include common afi-safi options.
       uses bgp-common-mp-all-afi-safi-common;

       // configuration options that are specific to IPv[46] unicast
       container config {
         description
           "Configuration parameters for common IPv4 and IPv6 unicast
           AFI-SAFI options";
         uses bgp-common-mp-ipv4-ipv6-unicast-common-config;
       }
       container state {
         config false;
         description
           "State information for common IPv4 and IPv6 unicast
           parameters";
         uses bgp-common-mp-ipv4-ipv6-unicast-common-config;
       }
     }

     grouping bgp-common-mp-l3vpn-ipv4-ipv6-unicast-common {
       description
         "Common configuration applied across L3VPN for IPv4
          and IPv6";

       // placeholder -- specific configuration options that are generic
       // across IPv[46] unicast address families.
       uses bgp-common-mp-all-afi-safi-common;
     }

     grouping bgp-common-mp-l3vpn-ipv4-ipv6-multicast-common {
       description
         "Common configuration applied across L3VPN for IPv4
         and IPv6";

       // placeholder -- specific configuration options that are
       // generic across IPv[46] multicast address families.
       uses bgp-common-mp-all-afi-safi-common;
     }

     grouping bgp-common-mp-l2vpn-common {
       description
         "Common configuration applied across L2VPN address
         families";

       // placeholder -- specific configuration options that are
       // generic across L2VPN address families
       uses bgp-common-mp-all-afi-safi-common;
     }

     // Config groupings for common groups
     grouping bgp-common-mp-all-afi-safi-common-prefix-limit-config {
       description
         "Configuration parameters relating to prefix-limits for an
         AFI-SAFI";

       leaf max-prefixes {
         type uint32;
         description
           "Maximum number of prefixes that will be accepted
           from the neighbour";
       }
       leaf shutdown-threshold-pct {
         type oc-types:percentage;
         description
           "Threshold on number of prefixes that can be received
           from a neighbour before generation of warning messages
           or log entries. Expressed as a percentage of
           max-prefixes";
       }

       leaf restart-timer {
         type decimal64 {
           fraction-digits 2;
         }
         units "seconds";
         description
           "Time interval in seconds after which the BGP session
           is re-established after being torn down due to exceeding
           the max-prefix limit.";
       }
     }

     grouping bgp-common-mp-ipv4-ipv6-unicast-common-config {
       description
         "Common configuration parameters for IPv4 and IPv6 Unicast
         address families";

       leaf send-default-route {
         type boolean;
         default "false";
         description
           "If set to true, send the default-route to the neighbour(s)";
       }
     }

   }
   <CODE ENDS>

<CODE BEGINS> file "ietf-bgp-common-structure.yang"

submodule ietf-bgp-common-structure {

  belongs-to ietf-bgp {
    prefix "bgp";
  }

  import openconfig-extensions { prefix oc-ext; }
  include ietf-bgp-common-multiprotocol;
  include ietf-bgp-common;

  // meta
  organization
    "OpenConfig working group";

  contact
    "OpenConfig working group
    netopenconfig@googlegroups.com";

  description
    "This sub-module contains groupings that are common across multiple BGP
    contexts and provide structure around other primitive groupings.";

  oc-ext:openconfig-version "2.1.1";

  revision "2016-06-21" {
    description
      "OpenConfig BGP refactor";
    reference "2.1.1";
  }

  grouping bgp-common-structure-neighbor-group-logging-options {
    description
      "Structural grouping used to include error handling configuration and
      state for both BGP neighbors and groups";

    container logging-options {
      description
        "Logging options for events related to the BGP neighbor or
        group";
      container config {
        description
          "Configuration parameters enabling or modifying logging
          for events relating to the BGPgroup";
        uses bgp-common-neighbor-group-logging-options-config;
      }
      container state {
        config false;
        description
          "State information relating to logging for the BGP neighbor
          or group";
        uses bgp-common-neighbor-group-logging-options-config;
      }
    }
  }
  grouping bgp-common-structure-neighbor-group-ebgp-multihop {
    description
      "Structural grouping used to include eBGP multihop configuration and
      state for both BGP neighbors and peer groups";

    container ebgp-multihop {
      description
        "eBGP multi-hop parameters for the BGPgroup";
      container config {
        description
          "Configuration parameters relating to eBGP multihop for the
          BGP group";
        uses bgp-common-neighbor-group-multihop-config;
      }
      container state {
        config false;
        description
          "State information for eBGP multihop, for the BGP neighbor
          or group";
        uses bgp-common-neighbor-group-multihop-config;
      }
    }
  }

  grouping bgp-common-structure-neighbor-group-route-reflector {
    description
      "Structural grouping used to include route reflector configuration and
      state for both BGP neighbors and peer groups";

    container route-reflector {
      description
        "Route reflector parameters for the BGPgroup";
      container config {
        description
          "Configuraton parameters relating to route reflection
          for the BGPgroup";
        uses bgp-common-neighbor-group-route-reflector-config;
      }
      container state {
        config false;
        description
          "State information relating to route reflection for the
          BGPgroup";
        uses bgp-common-neighbor-group-route-reflector-config;
      }
    }
  }
  grouping bgp-common-structure-neighbor-group-as-path-options {
    description
      "Structural grouping used to include AS_PATH manipulation configuration
      and state for both BGP neighbors and peer groups";

    container as-path-options {
      description
        "AS_PATH manipulation parameters for the BGP neighbor or
        group";
      container config {
        description
          "Configuration parameters relating to AS_PATH manipulation
          for the BGP peer or group";
         uses bgp-common-neighbor-group-as-path-options-config;
      }
      container state {
        config false;
        description
          "State information relating to the AS_PATH manipulation
          mechanisms bgp-common-mp-ipv4-ipv6-unicast-common;

         // placeholder for the BGP peer or group";
        uses bgp-common-neighbor-group-as-path-options-config;
      } IPv6 unicast specific configuration
         // options
       }
     }

     grouping bgp-common-structure-neighbor-group-add-paths bgp-common-mp-ipv4-labeled-unicast-group {
       description
      "Structural grouping used to include ADD-PATHs configuration and state
         "Group for both BGP neighbors and peer groups"; IPv4 Labeled Unicast configuration options";

       container add-paths ipv4-labeled-unicast {
      description
        "Parameters relating to the advertisement and receipt of
        multiple paths for a single NLRI (add-paths)";
      container config
         when "../afi-safi-name = 'bgp-types:IPV4_LABELED_UNICAST'" {
           description
          "Configuration parameters relating to ADD_PATHS";
        uses bgp-common-neighbor-group-add-paths-config;
      }
             "Include this container state {
        config false; for IPv4 Labeled Unicast specific
             configuration";
         }

         description
          "State information associated with ADD_PATHS"; "IPv4 Labeled Unicast configuration options";

         uses bgp-common-neighbor-group-add-paths-config;
      }
    } bgp-common-mp-all-afi-safi-common;

         // placeholder for IPv4 Labeled Unicast specific config
         // options
       }
     }

<CODE ENDS>

  <CODE BEGINS> file "ietf-bgp-peer-group.yang"

  submodule ietf-bgp-peer-group {

    belongs-to ietf-bgp

     grouping bgp-common-mp-ipv6-labeled-unicast-group {
      prefix "bgp";
    }

    import openconfig-extensions
       description
         "Group for IPv6 Labeled Unicast configuration options";

       container ipv6-labeled-unicast { prefix oc-ext; }
    import ietf-routing-policy
         when "../afi-safi-name = 'bgp-types:IPV6_LABELED_UNICAST'" { prefix rpol; }

    // Include the common submodule
    include ietf-bgp-common;
    include ietf-bgp-common-multiprotocol;
    include ietf-bgp-common-structure;

    // meta
    organization
      "OpenConfig working group";

    contact
      "OpenConfig working group
      netopenconfig@googlegroups.com";
           description
      "This sub-module contains groupings that are
             "Include this container for IPv6 Labeled Unicast specific to the
      peer-group context of the OpenConfig BGP module.";

    oc-ext:openconfig-version "2.1.1";

    revision "2016-06-21" {
             configuration";
         }

         description
        "OpenConfig BGP refactor";
      reference "2.1.1"; "IPv6 Labeled Unicast configuration options";

         uses bgp-common-mp-all-afi-safi-common;

         // placeholder for IPv6 Labeled Unicast specific config
         // options.
       }
     }

     grouping bgp-peer-group-config bgp-common-mp-l3vpn-ipv4-unicast-group {
       description
        "Configuration parameters relating to a base BGP peer group that
        are not also applicable to any other context (e.g., neighbor)";

      leaf peer-group-name
         "Group for IPv4 Unicast L3VPN configuration options";

       container l3vpn-ipv4-unicast {
         when "../afi-safi-name = 'bgp-types:L3VPN_IPV4_UNICAST'" {
        type string;
           description
          "Name of the BGP peer-group";
             "Include this container for IPv4 Unicast L3VPN specific
             configuration";
         }

         description "Unicast IPv4 L3VPN configuration options";

         // include common L3VPN configuration options
         uses bgp-common-mp-l3vpn-ipv4-ipv6-unicast-common;
         // placeholder for IPv4 Unicast L3VPN specific config options.
       }
     }

     grouping bgp-peer-group-afi-safi-list {
      description
        "List of address-families associated with the BGP peer-group";

      list afi-safi bgp-common-mp-l3vpn-ipv6-unicast-group {
        key "afi-safi-name";
       description
          "AFI,SAFI configuration available
         "Group for the
          neighbour or group";

        leaf afi-safi-name IPv6 Unicast L3VPN configuration options";

       container l3vpn-ipv6-unicast {
          type leafref
         when "../afi-safi-name = 'bgp-types:L3VPN_IPV6_UNICAST'" {
            path "../config/afi-safi-name";
          }
           description
            "Reference to the AFI-SAFI name used as a key
             "Include this container for the AFI-SAFI list"; unicast IPv6 L3VPN specific
             configuration";
         }

        container config {

         description
            "Configuration parameters for the AFI-SAFI"; "Unicast IPv6 L3VPN configuration options";

         // include common L3VPN configuration options
         uses bgp-common-mp-afi-safi-config; bgp-common-mp-l3vpn-ipv4-ipv6-unicast-common;

         // placeholder for IPv6 Unicast L3VPN specific configuration
         // options
       }
        container state
     }

     grouping bgp-common-mp-l3vpn-ipv4-multicast-group {
          config false;
       description
            "State information relating to the AFI-SAFI";
          uses bgp-common-mp-afi-safi-config;
        }
         "Group for IPv4 L3VPN multicast configuration options";

       container graceful-restart l3vpn-ipv4-multicast {
         when "../afi-safi-name = 'bgp-types:L3VPN_IPV4_MULTICAST'" {
           description
            "Parameters relating to BGP graceful-restart";
             "Include this container config { for multicast IPv6 L3VPN specific
             configuration";
         }

         description
              "Configuration "Multicast IPv4 L3VPN configuration options";

         // include common L3VPN multicast options for BGP graceful-restart";
         uses bgp-common-mp-afi-safi-graceful-restart-config; bgp-common-mp-l3vpn-ipv4-ipv6-multicast-common;

         // placeholder for IPv4 Multicast L3VPN specific configuration
         // options
       }
     }

     grouping bgp-common-mp-l3vpn-ipv6-multicast-group {
       description
         "Group for IPv6 L3VPN multicast configuration options";

       container state l3vpn-ipv6-multicast {
         when "../afi-safi-name = 'bgp-types:L3VPN_IPV6_MULTICAST'" {
            config false;
           description
              "State information
             "Include this container for BGP graceful-restart";
            uses bgp-common-mp-afi-safi-graceful-restart-config;
          } multicast IPv6 L3VPN specific
             configuration";
         }
         description "Multicast IPv6 L3VPN configuration options";

         // include common L3VPN multicast options
         uses bgp-common-route-selection-options;
        uses bgp-common-global-group-use-multiple-paths;
        uses bgp-common-mp-all-afi-safi-list-contents; bgp-common-mp-l3vpn-ipv4-ipv6-multicast-common;

         // placeholder for IPv6 Multicast L3VPN specific configuration
         // options
       }
     }

     grouping bgp-peer-group-base bgp-common-mp-l2vpn-vpls-group {
       description
        "Parameters related to a BGP group";
         "Group for BGP-signalled VPLS configuration options";

       container config l2vpn-vpls {
         when "../afi-safi-name = 'bgp-types:L2VPN_VPLS'" {
           description
          "Configuration parameters relating to the BGP neighbor or
          group";
        uses bgp-peer-group-config;
        uses bgp-common-neighbor-group-config;
      }
             "Include this container state {
        config false; for BGP-signalled VPLS specific
             configuration";
         }

         description
          "State information relating to the BGP peer-group";
        uses bgp-peer-group-config;
        uses bgp-common-neighbor-group-config; "BGP-signalled VPLS configuration options";

         // include common L2VPN options
         uses bgp-common-state; bgp-common-mp-l2vpn-common;

         // placeholder for BGP-signalled VPLS specific configuration
         // options
       }

      container timers
     }

     grouping bgp-common-mp-l2vpn-evpn-group {
       description
          "Timers related to a
         "Group for BGP peer-group"; EVPN configuration options";

       container config l2vpn-evpn {
         when "../afi-safi-name = 'bgp-types:L2VPN_EVPN'" {
           description
            "Configuration parameters relating to timers used
             "Include this container for the BGP neighbor or peer group";
          uses bgp-common-neighbor-group-timers-config; EVPN specific
             configuration";

         }
        container state {
          config false;

         description
            "State information relating to the timers used "BGP EVPN configuration options";

         // include common L2VPN options
         uses bgp-common-mp-l2vpn-common;

         // placeholder for the BGP
           group";
          uses bgp-common-neighbor-group-timers-config; EVPN specific configuration options
       }
     }

      container transport

     // Common groupings across multiple AFI,SAFIs
     grouping bgp-common-mp-all-afi-safi-common {
       description
          "Transport session parameters
         "Grouping for the BGP peer-group"; configuration common to all AFI,SAFI";

       container config prefix-limit {
         description
            "Configuration parameters
           "Parameters relating to the transport
            session(s) used prefix limit for the BGP neighbor AFI-SAFI";
         leaf max-prefixes {
           type uint32;
           description
             "Maximum number of prefixes that will be accepted from the
              neighbour";
         }
         leaf shutdown-threshold-pct {
           type bgp-types:percentage;
           description
             "Threshold on number of prefixes that can be received from
              a neighbour before generation of warning messages or group";
          uses bgp-common-neighbor-group-transport-config; log
              entries. Expressed as a percentage of max-prefixes";
         }
        container state

         leaf restart-timer {
          config false;
           type decimal64 {
             fraction-digits 2;
           }
           units "seconds";
           description
            "State information relating to the transport session(s)
            used for
             "Time interval in seconds after which the BGP neighbor or group";
          uses bgp-common-neighbor-group-transport-config; session is
              re-established after being torn down due to exceeding the
              max-prefix limit.";
         }
       }

      container error-handling {
        description
          "Error handling parameters used for the BGP peer-group";

        container config
     }

     grouping bgp-common-mp-ipv4-ipv6-unicast-common {
       description
            "Configuration parameters enabling or modifying the
            behavior or enhanced error handling mechanisms
         "Common configuration that is applicable for the BGP
            group"; IPv4 and IPv6
         unicast";

       // include common afi-safi options.
       uses bgp-common-neighbor-group-error-handling-config;
        }
        container state bgp-common-mp-all-afi-safi-common;

       // configuration options that are specific to IPv[46] unicast
       leaf send-default-route {
          config false;
         type boolean;
         default "false";
         description
            "State information relating
           "If set to enhanced error handling
            mechanisms for true, send the BGP group";
          uses bgp-common-neighbor-group-error-handling-config; default-route to the neighbour(s)";
       }
     }

      container graceful-restart

     grouping bgp-common-mp-l3vpn-ipv4-ipv6-unicast-common {
       description
          "Parameters relating the graceful restart mechanism
         "Common configuration applied across L3VPN for BGP";
        container config {
          description
            "Configuration parameters relating to graceful-restart"; IPv4
          and IPv6";

       // placeholder -- specific configuration options that are generic
       // across IPv[46] unicast address families.
       uses bgp-common-graceful-restart-config; bgp-common-mp-all-afi-safi-common;
     }
        container state

     grouping bgp-common-mp-l3vpn-ipv4-ipv6-multicast-common {
          config false;
       description
            "State information associated with graceful-restart";
         "Common configuration applied across L3VPN for IPv4
         and IPv6";

       // placeholder -- specific configuration options that are
       // generic across IPv[46] multicast address families.
       uses bgp-common-graceful-restart-config;
        } bgp-common-mp-all-afi-safi-common;
     }

      uses bgp-common-structure-neighbor-group-logging-options;
      uses bgp-common-structure-neighbor-group-ebgp-multihop;
      uses bgp-common-structure-neighbor-group-route-reflector;
      uses bgp-common-structure-neighbor-group-as-path-options;
      uses bgp-common-structure-neighbor-group-add-paths;
      uses bgp-common-global-group-use-multiple-paths;
      uses rpol:apply-policy-group;

      container afi-safis

     grouping bgp-common-mp-l2vpn-common {
       description
          "Per-address-family
         "Common configuration parameters associated with
          thegroup"; applied across L2VPN address
         families";

       // placeholder -- specific configuration options that are
       // generic across L2VPN address families
       uses bgp-peer-group-afi-safi-list;
      } bgp-common-mp-all-afi-safi-common;
     }

     // Config groupings for common groups
     grouping bgp-peer-group-list {
      description
        "The list of BGP peer groups";

      list peer-group {
        key "peer-group-name";
        description
          "List of BGP peer-groups configured on the local system -
          uniquely identified by peer-group name";

      leaf peer-group-name {
        type leafref bgp-common-mp-all-afi-safi-common-prefix-limit-config {
          path "../config/peer-group-name";
        }
       description
          "Reference
         "Configuration parameters relating to the name of the BGP peer-group used as a
          key in the peer-group list";
        }

        uses bgp-peer-group-base;
      } prefix-limits for an
         AFI-SAFI";

     }
   }
   <CODE ENDS>

   <CODE BEGINS> file "ietf-bgp-neighbor.yang" "ietf-bgp-common-structure@2018-05-09.yang"
   submodule ietf-bgp-neighbor ietf-bgp-common-structure {
     yang-version "1.1";
     belongs-to ietf-bgp {
       prefix "bgp";
     }

     import openconfig-extensions ietf-bgp-types { prefix oc-ext; bgp-types; }
     import ietf-routing-policy { prefix rpol; }
     import openconfig-types
     include ietf-bgp-common-multiprotocol;
     include ietf-bgp-common;

     // meta
     organization
       "IETF IDR Working Group";

     contact
       "WG Web:   <http://tools.ietf.org/wg/idr>
        WG List:  <idr@ietf.org>

        Editor:  Mahesh Jethanandani (mjethanandani@gmail.com)
        Authors: Keyur Patel,
                 Mahesh Jethanandani,
                 Susan Hares";

     description
       "This sub-module contains groupings that are common across
        multiple BGP contexts and provide structure around other
        primitive groupings.";

     revision "2018-05-09" { prefix oc-types;
       description
         "Initial Version";
       reference
         "RFC XXX, BGP Model for Service Provider Network.";
     }
     import ietf-bgp-types

     grouping bgp-common-structure-neighbor-group-logging-options { prefix oc-bgp-types;
       description
         "Structural grouping used to include error handling
          configuration and state for both BGP neighbors and groups";

       container logging-options {
         description
           "Logging options for events related to the BGP neighbor or
           group";

         leaf log-neighbor-state-changes {
           type boolean;
           default "true";
           description
             "Configure logging of peer state changes.  Default is to
              enable logging of peer state changes.";
         }
     import ietf-inet-types
       }
     }
     grouping bgp-common-structure-neighbor-group-ebgp-multihop { prefix inet;
       description
         "Structural grouping used to include eBGP multi-hop
          configuration and state for both BGP neighbors and peer
          groups";

       container ebgp-multihop {
         description
           "eBGP multi-hop parameters for the BGPgroup";

         leaf enabled {
           type boolean;
           default "false";
           description
             "When enabled the referenced group or neighbors are
              permitted to be indirectly connected - including cases
              where the TTL can be decremented between the BGP peers";
         }
     import ietf-yang-types

         leaf multihop-ttl {
           type uint8;
           description
             "Time-to-live value to use when packets are sent to the
              referenced group or neighbors and ebgp-multihop is
              enabled";
         }
       }
     }

     grouping bgp-common-structure-neighbor-group-route-reflector {
       description
         "Structural grouping used to include route reflector
          configuration and state for both BGP neighbors and peer
          groups";

       container route-reflector { prefix yang; }

     // Include
         description
           "Route reflector parameters for the common submodule
     include ietf-bgp-common;
     include ietf-bgp-common-multiprotocol;
     include ietf-bgp-peer-group;
     include ietf-bgp-common-structure;

     // meta
     organization
       "OpenConfig working group";

     contact
       "OpenConfig working group
       netopenconfig@googlegroups.com"; BGPgroup";

         leaf route-reflector-cluster-id {
           type bgp-types:rr-cluster-id-type;
           description
       "This sub-module contains groupings that are specific
             "route-reflector cluster id to use when local router is
              configured as a route reflector.  Commonly set at the
       neighbor context of the OpenConfig BGP module.";

     oc-ext:openconfig-version "2.1.1";

     revision "2016-06-21"
              group level, but allows a different cluster id to be set
              for each neighbor.";
         }

         leaf route-reflector-client {
           type boolean;
           default "false";
           description
         "OpenConfig BGP refactor";
       reference "2.1.1";
             "Configure the neighbor as a route reflector client.";
         }
       }
     }

     grouping bgp-neighbor-config bgp-common-structure-neighbor-group-as-path-options {
       description
         "Configuration parameters relating
         "Structural grouping used to a base include AS_PATH manipulation
          configuration and state for both BGP neighbor that
         are not also applicable to any other context
         (e.g., neighbors and peer group)";

       leaf peer-group {
         type leafref
          groups";

       container as-path-options {
           path "../../../../peer-groups/peer-group/peer-group-name";
         }
         description
           "The peer-group with which this
           "AS_PATH manipulation parameters for the BGP neighbor is associated";
       } or
           group";
         leaf neighbor-address allow-own-as {
           type inet:ip-address; uint8;
           default 0;
           description
             "Address
             "Specify the number of occurrences of the local BGP peer, either in IPv4 or IPv6";
              speaker's AS that can occur within the AS_PATH before it
              is rejected.";
         }

         leaf enabled replace-peer-as {
           type boolean;
           default true; "false";
           description
             "Whether
             "Replace occurrences of the BGP peer is enabled. In cases where peer's AS in the
             enabled leaf is set to false, AS_PATH with
              the local autonomous system should not
             initiate connections to the neighbor, and should not
             respond to TCP connections attempts from the neighbor. If
             the state of the BGP session is ESTABLISHED at the time
             that this leaf is set to false, the BGP session should be
             ceased."; number";
         }
       }
     }

     grouping bgp-neighbor-use-multiple-paths bgp-common-structure-neighbor-group-add-paths {
       description
         "Multipath
         "Structural grouping used to include ADD-PATHs configuration
          and state applicable to a for both BGP
         neighbor"; neighbors and peer groups";

       container use-multiple-paths add-paths {
         description
           "Parameters related relating to the use advertisement and receipt of multiple-paths
            multiple paths for the same a single NLRI when they are received only from this neighbor";

         container config (add-paths)";

         leaf receive {
           type boolean;
           default false;
           description
             "Configuration parameters relating
             "Enable ability to multipath";
           uses bgp-common-use-multiple-paths-config; receive multiple path advertisements for
              an NLRI from the neighbor or group";
         }
         container state

         leaf send-max {
           config false;
           type uint8;
           description
             "State parameters relating
             "The maximum number of paths to multipath";
           uses bgp-common-use-multiple-paths-config; advertise to neighbors for
              a single NLRI";
         }

         container ebgp
         leaf eligible-prefix-policy {
           description
             "Multipath configuration for eBGP";
           container config
           type leafref {
             description
               "Configuration parameters relating to eBGP multipath";
             uses bgp-common-use-multiple-paths-ebgp-as-options-config;
             path "/rpol:routing-policy/rpol:policy-definitions/" +
                  "rpol:policy-definition/rpol:name";
           }
           container state {
             config false;
           description
               "State information relating
             "A reference to eBGP multipath";
             uses bgp-common-use-multiple-paths-ebgp-as-options-config; a routing policy which can be used to
              restrict the prefixes for which add-paths is enabled";
         }
       }
     }
   }

     grouping bgp-neighbor-state {
       description
         "Operational state parameters relating only to a BGP neighbor";

       leaf session-state {
         type enumeration
   <CODE ENDS>

   <CODE BEGINS> file "ietf-bgp-peer-group@2018-05-09.yang"
   submodule ietf-bgp-peer-group {
             enum IDLE
     yang-version "1.1";
     belongs-to ietf-bgp {
               description
                 "neighbor is down, and in the Idle state of the
                 FSM";
       prefix "bgp";
     }
             enum CONNECT

     import ietf-routing-policy {
               description
                 "neighbor is down, and the session is waiting for
                 the underlying transport session to be established";
       prefix rpol;
     }
             enum ACTIVE {

     // Include the common submodule
     include ietf-bgp-common;
     include ietf-bgp-common-multiprotocol;
     include ietf-bgp-common-structure;

     // meta
     organization
       "IETF IDR Working Group";

     contact
       "WG Web:   <http://tools.ietf.org/wg/idr>
        WG List:  <idr@ietf.org>

        Editor:  Mahesh Jethanandani (mjethanandani@gmail.com)
        Authors: Keyur Patel,
                 Mahesh Jethanandani,
                 Susan Hares";

     description
                 "neighbor is down, and
       "This sub-module contains groupings that are specific to the local system is awaiting
                 a conncetion from
       peer-group context of the remote peer";
             }
             enum OPENSENT OpenConfig BGP module.";

     revision "2018-05-09" {
       description
                 "neighbor is in the process of being established.

                 The local system has sent an OPEN message";
         "Initial Version";
       reference
         "RFC XXX, BGP Model for Service Provider Network.";
     }
             enum OPENCONFIRM

     grouping bgp-peer-group-config {
       description
                 "neighbor is in the process of being established.
                 The local system is awaiting
         "Configuration parameters relating to a NOTIFICATION or
                 KEEPALIVE message";
             }
             enum ESTABLISHED base BGP peer group
          that are not also applicable to any other context (e.g.,
          neighbor)";

       leaf peer-group-name {
         type string;
         description
                 "neighbor is up -
           "Name of the BGP session with the peer is
                 established"; peer-group";

       }

     }

     grouping bgp-peer-group-afi-safi-list {
       description
           "Operational state
         "List of address-families associated with the BGP peer";
       }

       leaf last-established peer-group";

       list afi-safi {
         type oc-types:timeticks64;
         key "afi-safi-name";

         description
           "This timestamp indicates the time that
           "AFI,SAFI configuration available for the
           BGP session last transitioned in
           neighbour or out of the Established
           state.  The value is the timestamp in seconds relative group";

         uses bgp-common-mp-afi-safi-config;

         container graceful-restart {
           description
             "Parameters relating to
           the Unix Epoch (Jan 1, 1970 00:00:00 UTC).

           The BGP session uptime can be computed by clients as the
           difference between this value and the current time in UTC
           (assuming the session is in the ESTABLISHED state, per the
           session-state leaf)."; graceful-restart";

           uses bgp-common-mp-afi-safi-graceful-restart-config;
         }

       leaf established-transitions

         uses bgp-common-route-selection-options;
         uses bgp-common-global-group-use-multiple-paths;
         uses bgp-common-mp-all-afi-safi-list-contents;
       }
     }

     grouping bgp-peer-group-base {
         type yang:counter64;
       description
           "Number of transitions to the Established state for
           the neighbor session.  This value is analogous
         "Parameters related to the
           bgpPeerFsmEstablishedTransitions object from the standard
           BGP-4 MIB";
         reference
           "RFC 4273 - Definitions of Managed Objects for BGP-4";
       }

       leaf-list supported-capabilities {
         type identityref a BGP group";

       uses bgp-peer-group-config;
       uses bgp-common-neighbor-group-config;
       uses bgp-common-state;

       container timers {
           base oc-bgp-types:BGP_CAPABILITY;
         description
           "Timers related to a BGP peer-group";

         uses bgp-common-neighbor-group-timers-config;
       }

       container transport {
         description
           "BGP capabilities negotiated as supported with
           "Transport session parameters for the peer"; BGP peer-group";

         uses bgp-common-neighbor-group-transport-config;
       }

       container messages error-handling {
         description
           "Counters
           "Error handling parameters used for BGP messages sent and received from the
           neighbor"; BGP peer-group";

         uses bgp-common-neighbor-group-error-handling-config;
       }

       container sent graceful-restart {
         description
             "Counters
           "Parameters relating to BGP messages sent to the neighbor"; graceful restart mechanism for BGP";

         uses bgp-neighbor-counters-message-types-state; bgp-common-graceful-restart-config;
       }

       uses bgp-common-structure-neighbor-group-logging-options;
       uses bgp-common-structure-neighbor-group-ebgp-multihop;
       uses bgp-common-structure-neighbor-group-route-reflector;
       uses bgp-common-structure-neighbor-group-as-path-options;
       uses bgp-common-structure-neighbor-group-add-paths;
       uses bgp-common-global-group-use-multiple-paths;
       uses rpol:apply-policy-group;

       container received afi-safis {
         description
             "Counters for
           "Per-address-family configuration parameters associated with
           thegroup";
         uses bgp-peer-group-afi-safi-list;
       }
     }

     grouping bgp-peer-group-list {
       description
         "The list of BGP messages received from peer groups";

       list peer-group {
         key "peer-group-name";
         description
           "List of BGP peer-groups configured on the neighbor"; local system -
            uniquely identified by peer-group name";

         uses bgp-neighbor-counters-message-types-state; bgp-peer-group-base;
       }
     }
   }
   <CODE ENDS>
   <CODE BEGINS> file "ietf-bgp-neighbor@2018-05-09.yang"
   submodule ietf-bgp-neighbor {
     yang-version "1.1";
     belongs-to ietf-bgp {
       prefix "bgp";
     }

     import ietf-routing-policy {
       prefix rpol;
     }
     import ietf-bgp-types {
       prefix bgp-types;
     }
     import ietf-inet-types {
       prefix inet;
     }
     import ietf-yang-types {
       prefix yang;
     }

     // Include the common submodule
     include ietf-bgp-common;
     include ietf-bgp-common-multiprotocol;
     include ietf-bgp-peer-group;
     include ietf-bgp-common-structure;

     // meta
     organization
       "IETF IDR Working Group";

     contact
       "WG Web:   <http://tools.ietf.org/wg/idr>
        WG List:  <idr@ietf.org>

        Editor:  Mahesh Jethanandani (mjethanandani@gmail.com)
        Authors: Keyur Patel,
                 Mahesh Jethanandani,
                 Susan Hares";

     description
       "This sub-module contains groupings that are specific to the
        neighbor context of the OpenConfig BGP module.";

     revision "2018-05-09" {
       description
         "Initial Version";
       reference
         "RFC XXX, BGP Model for Service Provider Network.";

     }

     grouping bgp-neighbor-use-multiple-paths {
       description
         "Multi-path configuration and state applicable to a BGP
          neighbor";

       container queues use-multiple-paths {
         description
           "Counters
           "Parameters related to queued messages associated with the
           BGP use of multiple-paths for the same
            NLRI when they are received only from this neighbor";

         uses bgp-neighbor-queue-counters-state; bgp-common-use-multiple-paths-config;

         container ebgp {
           description
             "Multi-path configuration for eBGP";
           uses bgp-common-use-multiple-paths-ebgp-as-options-config;
         }
       }
     }

     grouping bgp-neighbor-counters-message-types-state {
       description
         "Grouping of BGP message types, included for re-use across
          counters";

       leaf UPDATE {
         type uint64;
         description
           "Number of BGP UPDATE messages announcing, withdrawing or
            modifying paths exchanged.";
       }

       leaf NOTIFICATION {
         type uint64;
         description
           "Number of BGP NOTIFICATION messages indicating an error
            condition has occurred exchanged.";
       }
     }

     grouping bgp-neighbor-queue-counters-state bgp-neighbor-afi-safi-list {
       description
         "Counters relating to the message queues
         "List of address-families associated with the BGP peer";

       leaf input {
         type uint32;
         description
           "The number of messages received from the peer currently
           queued";
       }

       leaf output {
         type uint32;
         description
           "The number of messages queued to be sent to the peer";
       }
     }

     grouping bgp-neighbor-transport-state neighbor";

       list afi-safi {
         key "afi-safi-name";
         description
         "Operational state parameters relating to the transport session
         used
           "AFI,SAFI configuration available for the BGP session"; neighbour or
            group";

         uses bgp-common-mp-afi-safi-config;

         leaf local-port active {
           type inet:port-number; boolean;
           config false;
           description
           "Local TCP port being used for
             "This value indicates whether a particular AFI-SAFI has
              been succesfully negotiated with the TCP session supporting peer. An AFI-SAFI may
              be enabled in the BGP session";
       }

       leaf remote-address {
         type inet:ip-address;
         description
           "Remote address current running configuration, but a
              session restart may be required in order to which negotiate the BGP session has been
           established";
              new capability.";
         }

       leaf remote-port

         container prefixes {
         type inet:port-number;
           config false;
           description
           "Remote port being used by the peer "Prefix counters for the TCP session
           supporting the BGP session";
       }
     }

     grouping bgp-neighbor-error-handling-state {
       description
         "Operational state parameters relating to enhanced error
         error handling for BGP";
           leaf erroneous-update-messages received {
             type uint32;
             description
               "The number of BGP UPDATE messages for which prefixes received from the
           treat-as-withdraw mechanism has been applied based
           on erroneous message contents";
       } neighbor";
           }

     grouping bgp-neighbor-timers-state

           leaf sent {
             type uint32;
             description
         "Operational state parameters relating
               "The number of prefixes advertised to BGP timers associated
         with the BGP session"; neighbor";
           }

           leaf negotiated-hold-time installed {
             type decimal64 {
           fraction-digits 2;
         } uint32;
             description
               "The negotiated hold-time for number of advertised prefixes installed in the BGP session";
                Loc-RIB";
           }
         }

     grouping bgp-neighbor-afi-safi-graceful-restart-state

         container graceful-restart {
       description
         "Operational state variables
           description
             "Parameters relating to the graceful-restart
         mechanism on a per-AFI-SAFI basis"; BGP graceful-restart";

           uses bgp-common-mp-afi-safi-graceful-restart-config;

           leaf received {
             type boolean;
             config false;
             description
               "This leaf indicates whether the neighbor advertised the
                ability to support graceful-restart for this AFI-SAFI";
           }

           leaf advertised {
             type boolean;
             config false;
             description
               "This leaf indicates whether the ability to support
                graceful-restart has been advertised to the peer";
           }
         }

         uses bgp-common-mp-all-afi-safi-list-contents;
         uses bgp-neighbor-use-multiple-paths;
       }
     }

     grouping bgp-neighbor-graceful-restart-state bgp-neighbor-base {
       description
         "Operational state information relevant
         "Parameters related to graceful restart
         for BGP"; a BGP neighbor";

       leaf peer-restart-time peer-group {
         type uint16 leafref {
           range 0..4096;
           path "../../../peer-groups/peer-group/peer-group-name";
         }
         description
           "The period of time (advertised by the peer) that
           the peer expects a restart of a BGP session to
           take"; peer-group with which this neighbor is associated";
       }

       leaf peer-restarting neighbor-address {
         type boolean; inet:ip-address;
         description
           "This flag indicates whether
           "Address of the remote neighbor is currently BGP peer, either in the process of restarting, and hence received routes are
           currently stale"; IPv4 or IPv6";
       }

       leaf local-restarting enabled {
         type boolean;
         default true;
         description
           "This flag indicates whether
           "Whether the local neighbor BGP peer is currently
           restarting. The flag enabled. In cases where the enabled
            leaf is unset after all NLRI have been
           advertised set to false, the peer, local system should not initiate
            connections to the neighbor, and should not respond to TCP
            connections attempts from the End-of-RIB (EOR) marker has
           been unset"; neighbor. If the state of the
            BGP session is ESTABLISHED at the time that this leaf is set
            to false, the BGP session should be ceased.";

       }

       uses bgp-common-neighbor-group-config;

       leaf mode session-state {
         type enumeration {
             enum HELPER_ONLY IDLE {
               description
               "The local router
                 "neighbor is operating in helper-only mode, down, and
               hence will not retain forwarding in the Idle state during a local of the FSM";
             }
             enum CONNECT {
               description
                 "neighbor is down, and the session restart, but will do so during is waiting for the
                  underlying transport session to be established";
             }
             enum ACTIVE {
               description
                 "neighbor is down, and the local system is awaiting a restart of
                  connection from the remote peer";
             }
             enum BILATERAL OPENSENT {
               description
               "The local router
                 "neighbor is operating in both helper mode, and
               hence retains forwarding state during a remote restart,
               and also maintains forwarding state during the process of being established.  The
                  local session
               restart"; system has sent an OPEN message";
             }
             enum REMOTE_HELPER OPENCONFIRM {
               description
               "The local system
                 "neighbor is able to retain routes during restart
               but in the remote process of being established.  The
                  local system is only able to act as awaiting a helper";
           } NOTIFICATION or KEEPALIVE
                  message";
             }
             enum ESTABLISHED {
               description
           "Ths leaf indicates
                 "neighbor is up - the mode of operation of BGP graceful
           restart session with the peer"; peer is
                  established";
             }
           }

     grouping bgp-neighbor-afi-safi-state {
         config false;
         description
           "Operational state parameters relating to an individual AFI,
         SAFI for a neighbor"; of the BGP peer";
       }

       leaf active last-established {
         // Was oc-types:timeticks64
         type boolean; uint64;
         config false;
         description
           "This value timestamp indicates whether a particular AFI-SAFI has
           been succesfully negotiated with the peer. An AFI-SAFI
           may be enabled time that the BGP session last
            transitioned in or out of the current running configuration, but a Established state.  The value
            is the timestamp in seconds relative to the Unix Epoch (Jan
            1, 1970 00:00:00 UTC).

            The BGP session restart may uptime can be required computed by clients as the
            difference between this value and the current time in order UTC
            (assuming the session is in the ESTABLISHED state, per the
            session-state leaf).";
       }

       leaf established-transitions {
         type yang:counter64;
         config false;
         description
           "Number of transitions to negotiate the new
           capability."; Established state for the
            neighbor session.  This value is analogous to the
            bgpPeerFsmEstablishedTransitions object from the standard
            BGP-4 MIB";
         reference
           "RFC 4273 - Definitions of Managed Objects for BGP-4";
       }

       leaf-list supported-capabilities {
         type identityref {
           base bgp-types:BGP_CAPABILITY;
         }
         config false;
         description
           "BGP capabilities negotiated as supported with the peer";
       }

       container prefixes messages {
         config false;
         description "Prefix counters
           "Counters for BGP messages sent and received from the
            neighbor";
         container sent {
           description
             "Counters relating to BGP session";
         leaf messages sent to the neighbor";
           uses bgp-neighbor-counters-message-types-state;
           }

         container received {
           type uint32;
           description
             "The number of prefixes
             "Counters for BGP messages received from the neighbor";
           uses bgp-neighbor-counters-message-types-state;
         }
       }
       container queues {
         config false;
         description
           "Counters related to queued messages associated with the BGP
            neighbor";

         leaf sent input {
           type uint32;
           description
             "The number of prefixes advertised to messages received from the neighbor"; peer currently
              queued";
         }

         leaf installed output {
           type uint32;
           description
             "The number of advertised prefixes installed in messages queued to be sent to the
             Loc-RIB";
         } peer";
         }
       }
     grouping bgp-neighbor-afi-safi-list

       container timers {
         description
         "List of address-families associated with the
           "Timers related to a BGP neighbor";

       list afi-safi {
         key "afi-safi-name";

         description
           "AFI,SAFI configuration available for the
           neighbour or group";

         uses bgp-common-neighbor-group-timers-config;

         leaf afi-safi-name negotiated-hold-time {
           type leafref decimal64 {
             path "../config/afi-safi-name";
           }
           description
             "Reference to the AFI-SAFI name used as a key
             for the AFI-SAFI list";
             fraction-digits 2;
           }

         container
           config { false;
           description
             "Configuration parameters
             "The negotiated hold-time for the AFI-SAFI";
           uses bgp-common-mp-afi-safi-config; BGP session";
         }
         container state {
           config false;
           description
             "State information relating to the AFI-SAFI";
           uses bgp-common-mp-afi-safi-config;
           uses bgp-neighbor-afi-safi-state;
       }

       container graceful-restart {
           description
             "Parameters relating to BGP graceful-restart";
           container config transport {
         description
               "Configuration options
           "Transport session parameters for the BGP graceful-restart"; neighbor";

         uses bgp-common-mp-afi-safi-graceful-restart-config;
           }
           container state bgp-common-neighbor-group-transport-config;

         leaf local-port {
           type inet:port-number;
           config false;
           description
               "State information
             "Local TCP port being used for BGP graceful-restart";
             uses bgp-common-mp-afi-safi-graceful-restart-config;
             uses bgp-neighbor-afi-safi-graceful-restart-state;
           }
         }

         uses bgp-common-mp-all-afi-safi-list-contents;
         uses bgp-neighbor-use-multiple-paths;
       }
     }

     grouping bgp-neighbor-base {
       description
         "Parameters related to a BGP neighbor";

       container config {
         description
           "Configuration parameters relating to the TCP session supporting
              the BGP neighbor or
           group";
         uses bgp-neighbor-config;
         uses bgp-common-neighbor-group-config; session";

         }
       container state

         leaf remote-address {
           type inet:ip-address;
           config false;
           description
           "State information relating
             "Remote address to which the BGP neighbor";
         uses bgp-neighbor-config;
         uses bgp-common-neighbor-group-config;
         uses bgp-neighbor-state; session has been
              established";
         }

       container timers

         leaf remote-port {
           type inet:port-number;
           config false;
           description
           "Timers related to a
             "Remote port being used by the peer for the TCP session
              supporting the BGP neighbor"; session";
         }
       }

       container config error-handling {
         description
             "Configuration
           "Error handling parameters relating to timers used for the BGP neighbor"; neighbor or
            group";
         uses bgp-common-neighbor-group-timers-config;
         }
         container state bgp-common-neighbor-group-error-handling-config;

         leaf erroneous-update-messages {
           type uint32;
           config false;
           description
             "State information relating to the timers used
             "The number of BGP UPDATE messages for which the BGP
             neighbor";
           uses bgp-common-neighbor-group-timers-config;
           uses bgp-neighbor-timers-state;
              treat-as-withdraw mechanism has been applied based on
              erroneous message contents";
         }
       }

       container transport graceful-restart {
         description
           "Transport session parameters
           "Parameters relating the graceful restart mechanism for BGP";

         uses bgp-common-graceful-restart-config;

         leaf peer-restart-time {
           type uint16 {
             range 0..4096;
           }
           config false;
           description
             "The period of time (advertised by the peer) that the peer
              expects a restart of a BGP neighbor";
         container config session to take";
         }

         leaf peer-restarting {
           type boolean;
           config false;
           description
             "Configuration parameters relating to
             "This flag indicates whether the transport
             session(s) used for remote neighbor is
              currently in the BGP neighbor";
           uses bgp-common-neighbor-group-transport-config; process of restarting, and hence received
              routes are currently stale";
         }
         container state

         leaf local-restarting {
           type boolean;
           config false;
           description
             "State information relating
             "This flag indicates whether the local neighbor is
              currently restarting. The flag is unset after all NLRI
              have been advertised to the transport session(s)
             used for peer, and the BGP neighbor";
           uses bgp-common-neighbor-group-transport-config;
           uses bgp-neighbor-transport-state;
         } End-of-RIB (EOR)
              marker has been unset";
         }

       container error-handling

         leaf mode {
           type enumeration {
             enum HELPER_ONLY {
               description
           "Error handling parameters used for
                 "The local router is operating in helper-only mode, and
                  hence will not retain forwarding state during a local
                  session restart, but will do so during a restart of
                  the BGP neighbor or
           group";
         container config remote peer";
             }
             enum BILATERAL {
               description
             "Configuration parameters enabling or modifying the
             behavior or enhanced error handling mechanisms for the BGP
             neighbor";
           uses bgp-common-neighbor-group-error-handling-config;
         }
         container
                 "The local router is operating in both helper mode, and
                  hence retains forwarding state during a remote
                  restart, and also maintains forwarding state during
                  local session restart";
             }
             enum REMOTE_HELPER {
           config false;
               description
             "State information relating
                 "The local system is able to enhanced error handling
             mechanisms for retain routes during
                  restart but the BGP neighbor";
           uses bgp-common-neighbor-group-error-handling-config;
           uses bgp-neighbor-error-handling-state; remote system is only able to act as a
                  helper";
             }
           }

       container graceful-restart {
           config false;
           description
           "Parameters relating
             "This leaf indicates the mode of operation of BGP graceful
              restart mechanism for BGP";
         container config {
           description
             "Configuration parameters relating to graceful-restart";
           uses bgp-common-graceful-restart-config;
         }
         container state {
           config false;
           description
             "State information associated with graceful-restart";
           uses bgp-common-graceful-restart-config;
           uses bgp-neighbor-graceful-restart-state; the peer";
         }
       }

       uses bgp-common-structure-neighbor-group-logging-options;
       uses bgp-common-structure-neighbor-group-ebgp-multihop;
       uses bgp-common-structure-neighbor-group-route-reflector;
       uses bgp-common-structure-neighbor-group-as-path-options;
       uses bgp-common-structure-neighbor-group-add-paths;
       uses bgp-neighbor-use-multiple-paths;
       uses rpol:apply-policy-group;

       container afi-safis {
         description
           "Per-address-family configuration parameters associated with
           the neighbor";
         uses bgp-neighbor-afi-safi-list;
       }
     }

     grouping bgp-neighbor-list {
       description
         "The list of BGP neighbors";

       list neighbor {
         key "neighbor-address";
         description
           "List of BGP neighbors configured on the local system,
           uniquely identified by peer IPv[46] address";

         leaf neighbor-address {
           type leafref {
             path "../config/neighbor-address";
           }
           description
             "Reference to the address of the BGP neighbor used as
             a key in the neighbor list";
         }

         uses bgp-neighbor-base;
       }
     }
   }
   <CODE ENDS>

   <CODE BEGINS> file "ietf-bgp-global.yang" "ietf-bgp-global@2018-05-09.yang"
   submodule ietf-bgp-global {
     yang-version "1.1";
     belongs-to ietf-bgp {
       prefix "bgp";
     }

     import openconfig-extensions { prefix oc-ext; bgp;
     }

     import ietf-inet-types {
       prefix inet;
     }
     import ietf-yang-types {
       prefix yang;
     }

     // Include common submodule

     include ietf-bgp-common;
     include ietf-bgp-common-multiprotocol;

     // meta

     organization
       "OpenConfig working group";
       "IETF IDR Working Group";

     contact
       "OpenConfig working group
       netopenconfig@googlegroups.com";
       "WG Web:   <http://tools.ietf.org/wg/idr>
        WG List:  <idr@ietf.org>

        Editor:  Mahesh Jethanandani (mjethanandani@gmail.com)
        Authors: Keyur Patel,
                 Mahesh Jethanandani,
                 Susan Hares";

     description
       "This sub-module contains groupings that are specific to the
        global context of the OpenConfig BGP module";

     oc-ext:openconfig-version "2.1.1";

     revision "2016-06-21" "2018-05-09" {
       description
         "OpenConfig BGP refactor";
         "Initial Version";
       reference "2.1.1";
         "RFC XXX, BGP Model for Service Provider Network.";
     }

     grouping bgp-global-config {
       description
         "Global configuration options for the BGP router.";

       leaf as {
         type inet:as-number;
         mandatory true;
         description
           "Local autonomous system number of the router.  Uses
           the 32-bit as-number type from the model in RFC 6991.";
       }

       leaf router-id {
         type yang:dotted-quad;
         description
           "Router id of the router - an unsigned 32-bit integer
           expressed in dotted quad notation.";
         reference
           "RFC4271 - A Border Gateway Protocol 4 (BGP-4),
           Section 4.2";
       }
     }

     grouping bgp-global-state {
       description
         "Operational state parameters for the BGP neighbor";

       uses bgp-common-state;
     }

     grouping bgp-global-default-route-distance-config {
       description
         "Configuration options relating to the administrative distance
         (or preference) assigned to routes received from different
         sources (external, internal, and local).";

       leaf external-route-distance {
         type uint8 {
           range "1..255";
         }
         description
           "Administrative distance for routes learned from external
           BGP (eBGP).";
       }
       leaf internal-route-distance {
         type uint8 {
           range "1..255";
         }
         description
           "Administrative distance for routes learned from internal
           BGP (iBGP).";
       }
     }

     grouping bgp-global-confederation-config {
       description
         "Configuration options specifying parameters when the local
         router is within an autonomous system which is part of a BGP
         confederation.";

       leaf enabled {
         type boolean;
         description
           "When this leaf is set to true it indicates that
           the local-AS is part of a BGP confederation";
       }
       leaf identifier {
         type inet:as-number;
         description
           "Confederation identifier for the autonomous system.";
       }

       leaf-list member-as {
         type inet:as-number;
         description
           "Remote autonomous systems that are to be treated
           as part of the local confederation.";
       }
     }

     grouping bgp-global-afi-safi-list {
       description
         "List of address-families associated with the BGP instance";

       list afi-safi {
         key "afi-safi-name";

         description
           "AFI,SAFI configuration available for the
           neighbour or group";

         leaf afi-safi-name {
           type leafref {
             path "../config/afi-safi-name";
           }
           description
             "Reference to the AFI-SAFI name used as a key
             for the AFI-SAFI list";
         }

         container config {
           description
             "Configuration parameters for the AFI-SAFI";
           uses bgp-common-mp-afi-safi-config;
         }
         container state address-families associated with the BGP instance";

       list afi-safi {
           config false;
         key "afi-safi-name";

         description
             "State information relating to
           "AFI,SAFI configuration available for the AFI-SAFI";
           neighbour or group";

         uses bgp-common-mp-afi-safi-config;
         uses bgp-common-state;
         }

         container graceful-restart {
           description
             "Parameters relating to BGP graceful-restart";
           container config {
             description
               "Configuration options for BGP graceful-restart";
             uses bgp-common-mp-afi-safi-graceful-restart-config;
           }
           container state {
             config false;
             description
               "State information for BGP graceful-restart";

           uses bgp-common-mp-afi-safi-graceful-restart-config;
         }
         }

         uses bgp-common-route-selection-options;
         uses bgp-common-global-group-use-multiple-paths;
         uses bgp-common-mp-all-afi-safi-list-contents;
       }
     }

     // Structural groupings
     grouping bgp-global-base {
       description
         "Global configuration parameters for the BGP router";

       container config {
         description
           "Configuration parameters relating to the global BGP router";
         uses bgp-global-config;
       }
       container state {
         config false;
         description
           "State information relating to the global BGP router";

       uses bgp-global-config;
       uses bgp-global-state;
       }
       container default-route-distance {
         description
           "Administrative distance (or preference) assigned to
           routes received from different sources
           (external, internal, and local).";

         container config {
           description
             "Configuration parameters relating to the default route
             distance";
           uses bgp-global-default-route-distance-config;
         }
         container state {
           config false;
           description
             "State information relating to the default route distance";

         uses bgp-global-default-route-distance-config;
       }
       }

       container confederation {
         description
           "Parameters indicating whether the local system acts as part
           of a BGP confederation";

         container config {
           description
             "Configuration parameters relating to BGP confederations";

         uses bgp-global-confederation-config;
       }

       container state {
           config false;
           description
             "State information relating to the BGP confederations";
           uses bgp-global-confederation-config;
         }
       }

       container graceful-restart {
         description
           "Parameters relating the graceful restart mechanism for BGP";
         container config {
           description
             "Configuration parameters relating to graceful-restart";
           uses bgp-common-graceful-restart-config;

         }
         container state {
           config false;
           description
             "State information associated with graceful-restart";
         uses bgp-common-graceful-restart-config;
       }
       }

       uses bgp-common-global-group-use-multiple-paths;
       uses bgp-common-route-selection-options;

       container afi-safis {
         description
           "Address family specific configuration";
         uses bgp-global-afi-safi-list;
       }
     }

   }
   <CODE ENDS>

8.  BGP types

   <CODE BEGINS> file "ietf-bgp-types.yang" "ietf-bgp-types@2018-05-09.yang"
   module ietf-bgp-types {
     yang-version "1"; "1.1";
     namespace "urn:ietf:params:xml:ns:yang:ietf-bgp-types";

     prefix "oc-bgp-types"; "bgp-types";

     import ietf-inet-types {
       prefix inet;

     }
     import openconfig-types { prefix oc-types; }
     import openconfig-extensions { prefix oc-ext; }

     // meta
     organization
       "OpenConfig working group";
       "IETF IDR Working Group";

     contact
       "OpenConfig working group
       netopenconfig@googlegroups.com";
       "WG Web:   <http://tools.ietf.org/wg/idr>
        WG List:  <idr@ietf.org>

        Editor:  Mahesh Jethanandani (mjethanandani@gmail.com)
        Authors: Keyur Patel,
                 Mahesh Jethanandani,
                 Susan Hares";

     description
       "This module contains general data definitions for use in BGP
       policy. It can be imported by modules that make use of BGP
       attributes";

     oc-ext:openconfig-version "2.1.1";

     revision "2016-06-21" "2018-05-09" {
       description
         "OpenConfig BGP refactor";
         "Initial Version";
       reference "2.1.1";
         "RFC XXX, BGP Model for Service Provider Network.";
     }

     identity BGP_CAPABILITY {
       description "Base identity for a BGP capability";
     }

     identity MPBGP {
       base BGP_CAPABILITY;
       description
         "Multi-protocol extensions to BGP";
       reference "RFC2858";
     }

     identity ROUTE_REFRESH {
       base BGP_CAPABILITY;
       description
         "The BGP route-refresh functionality";
       reference "RFC2918";
     }

     identity ASN32 {
       base BGP_CAPABILITY;
       description
         "4-byte (32-bit) AS number functionality";
       reference "RFC6793";
     }

     identity GRACEFUL_RESTART {
       base BGP_CAPABILITY;
       description
         "Graceful restart functionality";
       reference "RFC4724";
     }

     identity ADD_PATHS {
       base BGP_CAPABILITY;
       description
         "BGP add-paths";
       reference "draft-ietf-idr-add-paths";
     }

     identity AFI_SAFI_TYPE {
       description
         "Base identity type for AFI,SAFI tuples for BGP-4";
       reference "RFC4760 - multiprotocol multi-protocol extensions for BGP-4";
     }

     identity IPV4_UNICAST {
       base AFI_SAFI_TYPE;
       description
         "IPv4 unicast (AFI,SAFI = 1,1)";
       reference "RFC4760";
     }

     identity IPV6_UNICAST {
       base AFI_SAFI_TYPE;
       description
         "IPv6 unicast (AFI,SAFI = 2,1)";
       reference "RFC4760";
     }

     identity IPV4_LABELED_UNICAST {
       base AFI_SAFI_TYPE;
       description
         "Labeled IPv4 unicast (AFI,SAFI = 1,4)";
       reference "RFC3107";
     }

     identity IPV6_LABELED_UNICAST {
       base AFI_SAFI_TYPE;
       description
         "Labeled IPv6 unicast (AFI,SAFI = 2,4)";
       reference "RFC3107";
     }

     identity L3VPN_IPV4_UNICAST {
       base AFI_SAFI_TYPE;
       description
         "Unicast IPv4 MPLS L3VPN (AFI,SAFI = 1,128)";
       reference "RFC4364";
     }

     identity L3VPN_IPV6_UNICAST {
       base AFI_SAFI_TYPE;
       description
         "Unicast IPv6 MPLS L3VPN (AFI,SAFI = 2,128)";
       reference "RFC4659";
     }

     identity L3VPN_IPV4_MULTICAST {
       base AFI_SAFI_TYPE;
       description
         "Multicast IPv4 MPLS L3VPN (AFI,SAFI = 1,129)";
       reference "RFC6514";
     }

     identity L3VPN_IPV6_MULTICAST {
       base AFI_SAFI_TYPE;
       description
         "Multicast IPv6 MPLS L3VPN (AFI,SAFI = 2,129)";
       reference "RFC6514";
     }

     identity L2VPN_VPLS {
       base AFI_SAFI_TYPE;
       description
         "BGP-signalled VPLS (AFI,SAFI = 25,65)";
       reference "RFC4761";
     }

     identity L2VPN_EVPN {
       base AFI_SAFI_TYPE;
       description
         "BGP MPLS Based Ethernet VPN (AFI,SAFI = 25,70)";
     }

     identity BGP_WELL_KNOWN_STD_COMMUNITY {
       description
         "Reserved communities within the standard community space
         defined by RFC1997. These communities must fall within the
         range 0x00000000 to 0xFFFFFFFF";
       reference "RFC1997";
     }

     identity NO_EXPORT {
       base BGP_WELL_KNOWN_STD_COMMUNITY;
       description
         "Do not export NLRI received carrying this community outside
         the bounds of this autonomous system, or this confederation if
         the local autonomous system is a confederation member AS. This
         community has a value of 0xFFFFFF01.";
       reference "RFC1997";
     }

     identity NO_ADVERTISE {
       base BGP_WELL_KNOWN_STD_COMMUNITY;
       description
         "All NLRI received carrying this community must not be
         advertised to other BGP peers. This community has a value of
         0xFFFFFF02.";
       reference "RFC1997";
     }

     identity NO_EXPORT_SUBCONFED {
       base BGP_WELL_KNOWN_STD_COMMUNITY;
       description
         "All NLRI received carrying this community must not be
         advertised to external BGP peers - including over confederation
         sub-AS boundaries. This community has a value of 0xFFFFFF03.";
       reference "RFC1997";
     }

     identity NOPEER {
       base BGP_WELL_KNOWN_STD_COMMUNITY;
       description
         "An autonomous system receiving NLRI tagged with this community
         is advised not to readvertise re-advertise the NLRI to external bi-lateral
         peer autonomous systems. An AS may also filter received NLRI
         from bilateral peer sessions when they are tagged with this
         community value";
       reference "RFC3765";
     }

     typedef bgp-session-direction {
       type enumeration {
         enum INBOUND {
           description
             "Refers to all NLRI received from the BGP peer";
         }
         enum OUTBOUND {
           description
             "Refers to all NLRI advertised to the BGP peer";
         }
       }
       description
         "Type to describe the direction of NLRI transmission";
     }

     typedef bgp-well-known-community-type {
       type identityref {
         base BGP_WELL_KNOWN_STD_COMMUNITY;
       }
       description
         "Type definition for well-known IETF community attribute
         values";
       reference
         "IANA Border Gateway Protocol (BGP) Well Known Communities";
     }

     typedef bgp-std-community-type {
       // TODO: further refine restrictions and allowed patterns
       // 4-octet value:
       //  <as number> 2 octets
       //  <community value> 2 octets
       type union {
         type uint32 {
         // per RFC 1997, 0x00000000 - 0x0000FFFF and 0xFFFF0000 -
         // 0xFFFFFFFF are reserved
           range "65536..4294901759"; // 0x00010000..0xFFFEFFFF
         }
         type string {
           pattern '([0-9]+:[0-9]+)';
         }
       }
       description
         "Type definition for standard commmunity community attributes";
       reference "RFC 1997 - BGP Communities Attribute";
     }

     typedef bgp-ext-community-type {
       // TODO: needs more work to make this more precise given the
       // variability of extended community attribute specifications
       // 8-octet value:
       //  <type> 2 octects
       //  <value> 6 octets

       type union {
         type string {
           // Type 1: 2-octet global and 4-octet local
           //         (AS number)        (Integer)
           pattern '(6[0-5][0-5][0-3][0-5]|[1-5][0-9]{4}|'            +
                   '[1-9][0-9]{1,4}|[0-9]):'                          +
                   '(4[0-2][0-9][0-4][0-9][0-6][0-7][0-2][0-9][0-6]|' +
                   '[1-3][0-9]{9}|[1-9]([0-9]{1,7})?[0-9]|[1-9])';
         }
         type string {
           // Type 2: 4-octet global and 2-octet local
           //         (ipv4-address)     (integer)
           pattern '(([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|'      +
                   '25[0-5])\.){3}([0-9]|[1-9][0-9]|1[0-9][0-9]|'     +
                   '2[0-4][0-9]|25[0-5]):'                            +
                   '(6[0-5][0-5][0-3][0-5]|[1-5][0-9]{4}|'            +
                   '[1-9][0-9]{1,4}|[0-9])';
         }
         type string {
           // route-target with Type 1
           // route-target:(ASN):(local-part)
           pattern 'route\-target:(6[0-5][0-5][0-3][0-5]|'            +
                   '[1-5][0-9]{4}|[1-9][0-9]{1,4}|[0-9]):'            +
                   '(4[0-2][0-9][0-4][0-9][0-6][0-7][0-2][0-9][0-6]|' +
                   '[1-3][0-9]{9}|[1-9]([0-9]{1,7})?[0-9]|[1-9])';
         }
         type string {
           // route-target with Type 2
           // route-target:(IPv4):(local-part)
           pattern 'route\-target:' +
                   '(([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|'      +
                   '25[0-5])\.){3}([0-9]|[1-9][0-9]|1[0-9][0-9]|'     +
                   '2[0-4][0-9]|25[0-5]):'                            +
                   '(6[0-5][0-5][0-3][0-5]|[1-5][0-9]{4}|'            +
                   '[1-9][0-9]{1,4}|[0-9])';
         }
         type string {
           // route-origin with Type 1
           pattern 'route\-origin:(6[0-5][0-5][0-3][0-5]|'            +
                   '[1-5][0-9]{4}|[1-9][0-9]{1,4}|[0-9]):'            +
                   '(4[0-2][0-9][0-4][0-9][0-6][0-7][0-2][0-9][0-6]|' +
                   '[1-3][0-9]{9}|[1-9]([0-9]{1,7})?[0-9]|[1-9])';
         }
         type string {
           // route-origin with Type 2
           pattern 'route\-origin:' +
                   '(([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|'      +
                   '25[0-5])\.){3}([0-9]|[1-9][0-9]|1[0-9][0-9]|'     +
                   '2[0-4][0-9]|25[0-5]):'                            +
                   '(6[0-5][0-5][0-3][0-5]|[1-5][0-9]{4}|'            +
                   '[1-9][0-9]{1,4}|[0-9])';
         }
       }
       description
         "Type definition for extended community attributes";
       reference "RFC 4360 - BGP Extended Communities Attribute";
     }

     typedef bgp-community-regexp-type {
       // TODO: needs more work to decide what format these regexps can
       // take.

       type
       //type oc-types:std-regexp;
       type string;
       description
         "Type definition for communities specified as regular
         expression patterns";
     }

     typedef bgp-origin-attr-type {
       type enumeration {
         enum IGP {
           description "Origin of the NLRI is internal";
         }
         enum EGP {
           description "Origin of the NLRI is EGP";
         }
         enum INCOMPLETE {
           description "Origin of the NLRI is neither IGP or EGP";
         }
       }
       description
         "Type definition for standard BGP origin attribute";
       reference "RFC 4271 - A Border Gateway Protocol 4 (BGP-4),
         Sec 4.3";
     }

     typedef peer-type {
       type enumeration {
         enum INTERNAL {
           description "internal (iBGP) peer";
         }
         enum EXTERNAL {
           description "external (eBGP) peer";
         }

       }
       description
         "labels a peer or peer group as explicitly internal or
         external";
     }

     identity REMOVE_PRIVATE_AS_OPTION {
       description
         "Base identity for options for removing private autonomous
         system numbers from the AS_PATH attribute";
     }

     identity PRIVATE_AS_REMOVE_ALL {
       base REMOVE_PRIVATE_AS_OPTION;
       description
         "Strip all private autonmous system numbers from the AS_PATH.
         This action is performed regardless of the other content of the
         AS_PATH attribute, and for all instances of private AS numbers
         within that attribute.";
     }

     identity PRIVATE_AS_REPLACE_ALL {
       base REMOVE_PRIVATE_AS_OPTION;
       description
         "Replace all instances of private autonomous system numbers in
         the AS_PATH with the local BGP speaker's autonomous system
         number. This action is performed regardless of the other
         content of the AS_PATH attribute, and for all instances of
         private AS number within that attribute.";
     }

     typedef remove-private-as-option {
       type identityref {
         base REMOVE_PRIVATE_AS_OPTION;
       }
       description
         "set of options for configuring how private AS path numbers
         are removed from advertisements";
     }

     typedef percentage {
       type uint8 {
         range "0..100";
       }
       description
         "Integer indicating a percentage value";
     }
     typedef rr-cluster-id-type {
       type union {
         type uint32;
         type inet:ipv4-address;
       }
       description
         "union type for route reflector cluster ids:
         option 1: 4-byte number
         option 2: IP address";
     }

     typedef community-type {
       type enumeration {
         enum STANDARD {
           description "send only standard communities";
         }
         enum EXTENDED {
           description "send only extended communities";
         }
         enum BOTH {
           description "send both standard and extended communities";
         }
         enum NONE {
           description "do not send any community attribute";
         }
       }
       description
         "type describing variations of community attributes:
         STANDARD: standard BGP community [rfc1997]
         EXTENDED: extended BGP community [rfc4360]
         BOTH: both standard and extended community";
     }
   }
   <CODE ENDS>

9.  BGP policy data

       <CODE BEGINS> file "ietf-bgp-policy.yang" "ietf-bgp-policy@2018-05-09.yang"
   module ietf-bgp-policy {
     yang-version "1"; "1.1";

     // namespace
     namespace "urn:ietf:params:xml:ns:yang:ietf-bgp-policy";

     prefix "oc-bgp-pol"; "bgp-pol";

     // import some basic types
     import ietf-inet-types {
       prefix inet;
     }
     import ietf-routing-policy {prefix rpol; }
  import openconfig-policy-types {
       prefix pol-types; rpol;
     }
     import ietf-bgp-types {
       prefix oc-bgp-types; bgp-types;
     }

     import openconfig-extensions ietf-routing-types {
       prefix oc-ext; rt-types;
     }

     // meta
     organization
    "OpenConfig working group";
       "IETF IDR Working Group";

     contact
    "OpenConfig working group
    netopenconfig@googlegroups.com";
       "WG Web:   <http://tools.ietf.org/wg/idr>
        WG List:  <idr@ietf.org>

        Editor:  Mahesh Jethanandani (mjethanandani@gmail.com)
        Authors: Keyur Patel,
                 Mahesh Jethanandani,
                 Susan Hares";

     description
       "This module contains data definitions for BGP routing policy.
       It augments the base routing-policy module with BGP-specific
       options for conditions and actions.";

  oc-ext:openconfig-version "2.1.1";

     revision "2016-06-21" "2018-05-09" {
       description
      "OpenConfig BGP refactor";
         "Initial Version";
       reference "2.1.1";
         "RFC XXX, BGP Model for Service Provider Network.";
     }

     // typedef statements

     typedef bgp-set-community-option-type {
       type enumeration {
         enum ADD {
           description
             "add the specified communities to the existing
             community attribute";

         }
         enum REMOVE {
           description
             "remove the specified communities from the
             existing community attribute";
         }
         enum REPLACE {
           description
             "replace the existing community attribute with
             the specified communities. If an empty set is
             specified, this removes the community attribute
             from the route.";
         }
       }
       description
         "Type definition for options when setting the community
         attribute in a policy action";
     }

     typedef bgp-next-hop-type {
       type union {
         type inet:ip-address-no-zone;
         type enumeration {
           enum SELF {
             description "special designation for local router's own
             address, i.e., next-hop-self";
           }
         }
       }
       description
         "type definition for specifying next-hop in policy actions";
     }

     typedef bgp-set-med-type {
       type union {
         type uint32;
         type string {
           pattern "^[+-][0-9]+";
         }
         type enumeration {
           enum IGP {
             description "set the MED value to the IGP cost toward the
             next hop for the route";
           }
         }
       }
       description
         "Type definition for specifying how the BGP MED can
         be set in BGP policy actions. The three choices are to set
         the MED directly, increment/decrement using +/- notation,
      and setting it to the IGP cost (predefined value).";
  }

  // grouping statements

  grouping match-community-config {
    description
      "Configuration data for match conditions on communities";

    leaf community-set {
      type leafref {
        path "/rpol:routing-policy/rpol:defined-sets/" +
          "oc-bgp-pol:bgp-defined-sets/oc-bgp-pol:community-sets/" +
          "oc-bgp-pol:community-set/oc-bgp-pol:community-set-name";
      }
      description
        "References a defined community set";
    }

    uses rpol:match-set-options-group;
  }
  grouping match-community-state {
    description
      "Operational state data for match conditions on communities";
         and setting it to the IGP cost (predefined value).";
     }

     // grouping statements

     grouping match-community-top {
       description
         "Top-level grouping for match conditions on communities";

       container match-community-set {
         description
           "Top-level container for match conditions on communities.
           Match a referenced community-set according to the logic
           defined in the match-set-options leaf";

      container config {
        description
          "Configuration data for match conditions on communities";

        uses match-community-config;
      }

      container state {

        config false;

        description
          "Operational state data ";

        uses match-community-config;
        uses match-community-state;
      }
    }
  }

  grouping match-ext-community-config {
    description
      "Configuration data for match conditions on extended
      communities";

         leaf ext-community-set community-set {
           type leafref {
             path
               "/rpol:routing-policy/rpol:defined-sets/" +
            "oc-bgp-pol:bgp-defined-sets/oc-bgp-pol:ext-community-sets/" +
            "oc-bgp-pol:ext-community-set/"
               "bgp-pol:bgp-defined-sets/bgp-pol:community-sets/" +
            "oc-bgp-pol:ext-community-set-name";
               "bgp-pol:community-set/bgp-pol:community-set-name";
           }
           description
             "References a defined extended community set";
         }

         uses rpol:match-set-options-group;
       }

  grouping match-ext-community-state {
    description
      "Operational state data for match conditions on extended
      communities";
     }

     grouping match-ext-community-top {
       description
         "Top-level grouping for match conditions on extended
         communities";

       container match-ext-community-set {
         description
           "Match a referenced extended community-set according to the
           logic defined in the match-set-options leaf";

      container config {
        description
          "Configuration data for match conditions on extended
          communities";

        uses match-ext-community-config;
      }

      container state {

        config false;

        description
          "Operational state data for match conditions on extended
          communities";

        uses match-ext-community-config;
        uses match-ext-community-state;
      }
    }
  }

  grouping match-as-path-config {
    description
      "Configuration data for match conditions on AS path set";

         leaf as-path-set ext-community-set {
           type leafref {
             path
               "/rpol:routing-policy/rpol:defined-sets/" +
          "oc-bgp-pol:bgp-defined-sets/oc-bgp-pol:as-path-sets/"
               "bgp-pol:bgp-defined-sets/bgp-pol:ext-community-sets/" +
               "bgp-pol:ext-community-set/" +
          "oc-bgp-pol:as-path-set/oc-bgp-pol:as-path-set-name";
               "bgp-pol:ext-community-set-name";
           }
           description "References a defined AS path extended community set";
         }

         uses rpol:match-set-options-group;
       }

  grouping match-as-path-state {
    description
      "Operational state data for match conditions on AS path set";
     }

     grouping match-as-path-top {
       description
         "Top-level grouping for match conditions on AS path set";

       container match-as-path-set {
         description
           "Match a referenced as-path set according to the logic
           defined in the match-set-options leaf";

      container config

         leaf as-path-set {
           type leafref {
        description
          "Configuration data for match conditions on AS
             path set";

        uses match-as-path-config; "/rpol:routing-policy/rpol:defined-sets/" +
               "bgp-pol:bgp-defined-sets/bgp-pol:as-path-sets/" +
               "bgp-pol:as-path-set/bgp-pol:as-path-set-name";
           }

      container state {

        config false;
           description
          "Operational state data for match conditions on "References a defined AS path set";

        uses match-as-path-config;
        uses match-as-path-state;
         }
         uses rpol:match-set-options-group;
       }
     }

     grouping bgp-match-set-conditions {
       description
         "Condition statement definitions for checking membership in a
         defined set";

       uses match-community-top;
       uses match-ext-community-top;
    uses match-as-path-top;
  }

  grouping community-count-config {
    description
      "Configuration data for community count condition";

    uses pol-types:attribute-compare-operators;
  }

  grouping community-count-state {
    description
      "Operational state data for community count condition";
  }

  grouping community-count-top {
    description
      "Top-level grouping for community count condition";

    container community-count {
      description
        "Value and comparison operations for conditions based on the
        number of communities in the route update";

      container config {
        description
          "Configuration data for community count condition";

        uses community-count-config;
      }

      container state {

        config false;

        description
          "Operational state data for community count condition";

        uses community-count-config;
        uses community-count-state;
      }
    }
       uses match-as-path-top;
     }

     grouping as-path-length-config community-count-top {
       description
      "Configuration data
         "Top-level grouping for AS path length community count condition";

    uses pol-types:attribute-compare-operators;
  }

  grouping as-path-length-state

       container community-count {
         description
      "Operational state data
           "Value and comparison operations for AS path length condition"; conditions based on the
           number of communities in the route update";
       }
     }

     grouping as-path-length-top {
       description
         "Top-level grouping for AS path length condition";

       container as-path-length {
         description
           "Value and comparison operations for conditions based on the
           length of the AS path in the route update";

      container config {
        description
          "Configuration data for AS path length condition";

        uses as-path-length-config;
      }

      container state {

        config false;

        description
          "Operational state data for AS path length condition";

        uses as-path-length-config;
        uses as-path-length-state;
      }
       }
     }

     grouping bgp-conditions-config bgp-conditions-top {
       description
      "Configuration data
         "Top-level grouping for BGP-specific policy conditions";

       container bgp-conditions {
         description
           "Top-level container ";

         leaf med-eq {
           type uint32;
           description
             "Condition to check if the received MED value is equal to
              the specified value";
         }

         leaf origin-eq {
           type oc-bgp-types:bgp-origin-attr-type; bgp-types:bgp-origin-attr-type;
           description
             "Condition to check if the route origin is equal to the
              specified value";
         }

         leaf-list next-hop-in {
           type inet:ip-address-no-zone;
           description
             "List of next hop addresses to check for in the route
              update";
         }

         leaf-list afi-safi-in {
           type identityref {
             base oc-bgp-types:AFI_SAFI_TYPE; bgp-types:AFI_SAFI_TYPE;
           }
           description
             "List of address families which the NLRI may be within";
         }

         leaf local-pref-eq {
           type uint32;
           // TODO: add support for other comparisons if needed
           description
             "Condition to check if the local pref attribute is equal to
              the specified value";
         }

         leaf route-type {
           // TODO: verify extent of vendor support for this comparison
           type enumeration {
             enum INTERNAL {
               description "route type is internal";
             }
             enum EXTERNAL {
               description "route type is external";
             }
           }
           description
             "Condition to check the route type in the route update";
         }

  }

  grouping bgp-conditions-state {
    description
      "Operational state data for BGP-specific policy conditions";
  }

  grouping bgp-conditions-top {
    description
      "Top-level grouping for BGP-specific policy conditions";

    container bgp-conditions {
      description
        "Top-level container ";

      container config {
        description
          "Configuration data for BGP-specific policy conditions";

        uses bgp-conditions-config;
      }

      container state {

        config false;

        description
          "Operational state data for BGP-specific policy
          conditions";

        uses bgp-conditions-config;
        uses bgp-conditions-state;
      }

         uses community-count-top;
         uses as-path-length-top;
         uses bgp-match-set-conditions;
       }
     }

     grouping community-set-config {
    description
      "Configuration data for BGP community sets";

    leaf community-set-name {
      type string;
      mandatory true;
      description
        "name / label of the community set -- this is used to
        reference the set in match conditions";
    }

    leaf-list community-member {
      type union {
        type oc-bgp-types:bgp-std-community-type;
        type oc-bgp-types:bgp-community-regexp-type;
        type oc-bgp-types:bgp-well-known-community-type;
      }
      description
        "members of the community set";
    }
  }

  grouping community-set-state {
    description
      "Operational state data for BGP community sets";
  }

  grouping community-set-top {
       description
         "Top-level grouping for BGP community sets";

       container community-sets {
         description
           "Enclosing container for list of defined BGP community sets";

         list community-set {
           key "community-set-name";
           description
          "List of defined BGP community sets";

        leaf community-set-name {
          type leafref {
            path "../config/community-set-name";
          }
          description
            "Reference to list key";
        }

        container config {
          description
            "Configuration data for BGP community sets";

          uses community-set-config;
        }
        container state {

          config false;

          description
            "Operational state data for BGP community sets";

          uses community-set-config;
          uses community-set-state;
        }
      }
    }
  }

  grouping ext-community-set-config {
    description
      "Configuration data for extended
             "List of defined BGP community sets";

           leaf ext-community-set-name community-set-name {
             type string;
             mandatory true;
             description
               "name / label of the extended community set -- this is used to
                reference the set in match conditions";
           }

           leaf-list ext-community-member community-member {
             type union {
               type oc-bgp-types:bgp-ext-community-type; bgp-types:bgp-std-community-type;
               type oc-bgp-types:bgp-community-regexp-type; bgp-types:bgp-community-regexp-type;
               type bgp-types:bgp-well-known-community-type;
             }
             description
               "members of the extended community set";
           }
         }

  grouping ext-community-set-state {
    description
      "Operational state data for extended BGP community sets";
       }
     }

     grouping ext-community-set-top {
       description
         "Top-level grouping for extended BGP community sets";

       container ext-community-sets {
         description
           "Enclosing container for list of extended BGP community
           sets";
         list ext-community-set {
           key "ext-community-set-name";
           description
             "List of defined extended BGP community sets";

           leaf ext-community-set-name {
             type leafref {
            path "../config/ext-community-set-name";
          }
          description
            "Reference to list key";
        }

        container config {
          description
            "Configuration data for extended BGP community sets";

          uses ext-community-set-config;
        }

        container state {

          config false;

          description
            "Operational state data for extended BGP community sets";

          uses ext-community-set-config;
          uses ext-community-set-state;
        }
      }
    }
  }

  grouping as-path-set-config {
    description
      "Configuration data for AS path sets";

    leaf as-path-set-name {
      type string;
             description
               "name / label of the AS path extended community set -- this is
                used to reference the set in match conditions";
           }

           leaf-list as-path-set-member ext-community-member {
      // TODO: need to refine typedef for AS path expressions
             type string; union {
               type rt-types:route-target;
               type bgp-types:bgp-community-regexp-type;
             }
             description
          "AS path expression -- list
               "members of ASes in the extended community set";
           }
         }

  grouping as-path-set-state {
    description
      "Operational state data for AS path sets";
       }

     }

     grouping as-path-set-top {
       description
         "Top-level grouping for AS path sets";

       container as-path-sets {
         description
           "Enclosing container for list of define AS path sets";

         list as-path-set {
           key "as-path-set-name";
           description
             "List of defined AS path sets";

           leaf as-path-set-name {
             type leafref {
            path "../config/as-path-set-name";
          } string;
             description
            "Reference
               "name of the AS path set -- this is used to list key"; reference the
                set in match conditions";
           }

        container config

           leaf-list as-path-set-member {
          description
            "Configuration data
             // TODO: need to refine typedef for AS path sets";

          uses as-path-set-config;
        }

        container state {

          config false; expressions
             type string;
             description
            "Operational state data for AS
               "AS path sets";

          uses as-path-set-config;
          uses as-path-set-state; expression -- list of ASes in the set";
           }
         }
       }
     }

     // augment statements

     augment "/rpol:routing-policy/rpol:defined-sets" {
       description "adds BGP defined sets container to routing policy
       model";

       container bgp-defined-sets {
         description
           "BGP-related set definitions for policy match conditions";

         uses community-set-top;
         uses ext-community-set-top;
      uses as-path-set-top;
    }
  }

  grouping as-path-prepend-config {
    description
      "Configuration data for the AS path prepend action";

    leaf repeat-n {
      type uint8 {
        range 1..max;
      }
      description
        "Number of times to prepend the local AS number to the AS
        path.  The value should be between 1 and the maximum
        supported by the implementation.";
    }
  }

  grouping as-path-prepend-state {
    description
      "Operational state data for the AS path prepend action"; ext-community-set-top;
         uses as-path-set-top;
       }
     }
     grouping as-path-prepend-top {
       description
         "Top-level grouping for the AS path prepend action";

       container set-as-path-prepend {
         description
           "action to prepend local AS number to the AS-path a
           specified number of times";

      container config

         leaf repeat-n {
           type uint8 {
             range 1..max;
           }
           description
          "Configuration data for
             "Number of times to prepend the local AS path prepend action";

        uses as-path-prepend-config;
      }

      container state {

        config false;

        description
          "Operational state data for number to the AS path prepend action";

        uses as-path-prepend-config;
        uses as-path-prepend-state;
              path.  The value should be between 1 and the maximum
              supported by the implementation.";
         }
       }
     }

     grouping set-community-action-common {
       description
         "Common leaves for set-community and set-ext-community
         actions";

       leaf method {
         type enumeration {
           enum INLINE {
             description
               "The extended communities are specified inline as a
               list";
           }
           enum REFERENCE {
             description
               "The extended communities are specified by referencing a
               defined ext-community set";
           }
         }
         description
           "Indicates the method used to specify the extended
           communities for the set-ext-community action";
       }

       leaf options {
         type bgp-set-community-option-type;
         description
           "Options for modifying the community attribute with
           the specified values.  These options apply to both
           methods of setting the community attribute.";
       }
     }

     grouping set-community-inline-config {
    description
      "Configuration data for inline specification of set-community
      action";

    leaf-list communities {
      type union {
        type oc-bgp-types:bgp-std-community-type;
        type oc-bgp-types:bgp-well-known-community-type;
      }
      description
        "Set the community values for the update inline with
        a list.";
    }
  }

  grouping set-community-inline-state {
    description
      "Operational state data or inline specification of
      set-community action";
  }

  grouping set-community-inline-top {
       description
         "Top-level grouping or inline specification of set-community
         action";

       container inline {
         when "../config/method=INLINE" {
           description
             "Active only when the set-community method is INLINE";
         }
         description
           "Set the community values for the action inline with
           a list.";

      container config

         leaf-list communities {
        description
          "Configuration data or inline specification of set-community
      action";

        uses set-community-inline-config;
      }
      container state
           type union {

        config false;

        description
          "Operational state data or inline specification of
          set-community action";

        uses set-community-inline-config;
        uses set-community-inline-state;
      }
    }
             type bgp-types:bgp-std-community-type;
             type bgp-types:bgp-well-known-community-type;
           }

  grouping set-community-reference-config {
           description
      "Configuration data
             "Set the community values for referening a community-set in the
      set-community action";

    leaf community-set-ref {
      type leafref {
        path "/rpol:routing-policy/rpol:defined-sets/" +
          "oc-bgp-pol:bgp-defined-sets/" +
          "oc-bgp-pol:community-sets/oc-bgp-pol:community-set/" +
          "oc-bgp-pol:community-set-name";
      }
      description
        "References update inline with a defined community set by name";
              list.";
         }
       }

  grouping set-community-reference-state {
    description
      "Operational state data for referening a community-set in the
      set-community action";
     }

     grouping set-community-reference-top {
       description
         "Top-level grouping for referening referencing a community-set in the
         set-community action";

       container reference {
         when "../config/method=REFERENCE" {
           description
             "Active only when the set-community method is REFERENCE";
         }
         description
           "Provide a reference to a defined community set for the
           set-community action";

      container config {
        description
          "Configuration data for referening a community-set in the
      set-community action";

        uses set-community-reference-config;
      }

      container state {

        config false;

        description
          "Operational state data for referening a community-set
          in the set-community action";

        uses set-community-reference-config;
        uses set-community-reference-state;
      }
    }
  }

  grouping set-community-action-config {
    description
      "Configuration data for the set-community action";

    uses set-community-action-common;
  }

  grouping set-community-action-state {
    description
      "Operational state data for the set-community action";

         leaf community-set-ref {
           type leafref {
             path "/rpol:routing-policy/rpol:defined-sets/" +
               "bgp-pol:bgp-defined-sets/" +
               "bgp-pol:community-sets/bgp-pol:community-set/" +
               "bgp-pol:community-set-name";
           }
           description
             "References a defined community set by name";
         }
       }
     }

     grouping set-community-action-top {
       description
         "Top-level grouping for the set-community action";

       container set-community {
         description
           "Action to set the community attributes of the route, along
           with options to modify how the community is modified.
           Communities may be set using an inline list OR
           reference to an existing defined set (not both).";

      container config {
        description
          "Configuration data for the set-community action";

         uses set-community-action-config;
      }

      container state {

        config false;

        description
          "Operational state data for the set-community action";

        uses set-community-action-config;
        uses set-community-action-state;
      } set-community-action-common;
         uses set-community-inline-top;
         uses set-community-reference-top;
       }
     }

     grouping set-ext-community-inline-config {
    description
      "Configuration data for inline specification of
      set-ext-community action";

    leaf-list communities {
      type union {
        type oc-bgp-types:bgp-ext-community-type;
        type oc-bgp-types:bgp-well-known-community-type;
      }
      description
        "Set the extended community values for the update inline
        with a list.";
    }
  }

  grouping set-ext-community-inline-state {
    description
      "Operational state data or inline specification of
      set-ext-community action";
  }

  grouping set-ext-community-inline-top {
       description
         "Top-level grouping or inline specification of
          set-ext-community action";

       container inline {
         when "../config/method=INLINE" {
           description
             "Active only when the set-community method is INLINE";
         }
         description
           "Set the extended community values for the action inline with
           a list.";

      container config {
        description
          "Configuration data or inline specification of
          set-ext-community action";

        uses set-ext-community-inline-config;
      }

      container state {

        config false;

        description
          "Operational state data or inline specification of
          set-ext-community action";

        uses set-ext-community-inline-config;
        uses set-ext-community-inline-state;
      }
    }
  }

  grouping set-ext-community-reference-config {
    description
      "Configuration data for referening a extended community-set
      in the set-ext-community action";

    leaf ext-community-set-ref

         leaf-list communities {
           type leafref union {
        path "/rpol:routing-policy/rpol:defined-sets/" +
          "oc-bgp-pol:bgp-defined-sets/" +
          "oc-bgp-pol:ext-community-sets/" +
          "oc-bgp-pol:ext-community-set/" +
          "oc-bgp-pol:ext-community-set-name";
             type rt-types:route-target;
             type bgp-types:bgp-well-known-community-type;
           }
           description
        "References a defined
             "Set the extended community set by
        name";
    }
  }

  grouping set-ext-community-reference-state {
    description
      "Operational state data values for referening an extended
      community-set in the set-ext-community action"; update inline
              with a list.";
         }
       }
     }

     grouping set-ext-community-reference-top {
       description
         "Top-level grouping for referening an extended community-set
         in the set-community action";

       container reference {
         when "../config/method=REFERENCE" {
           description
             "Active only when the set-community method is REFERENCE";
         }
         description
           "Provide a reference to an extended community set for the
        set-ext-community action";

      container config {
        description
          "Configuration data for referening an extended
          community-set in the set-ext-community action";

        uses set-ext-community-reference-config;
      }

      container state {

        config false;

        description
          "Operational state data for referening an extended
          community-set in the set-ext-community action";

        uses set-ext-community-reference-config;
        uses set-ext-community-reference-state;
      }
    }
  }

  grouping set-ext-community-action-config {
    description
      "Configuration data for the set-ext-community action";

    uses set-community-action-common;
  }

  grouping set-ext-community-action-state {
    description
      "Operational state data extended community set for the
           set-ext-community action";

         leaf ext-community-set-ref {
           type leafref {
             path
               "/rpol:routing-policy/rpol:defined-sets/" +
               "bgp-pol:bgp-defined-sets/bgp-pol:ext-community-sets/" +
               "bgp-pol:ext-community-set/" +
               "bgp-pol:ext-community-set-name";
           }
           description
             "References a defined extended community set by name";
         }
       }
     }

     grouping set-ext-community-action-top {
       description
         "Top-level grouping for the set-ext-community action";

       container set-ext-community {
         description
           "Action to set the extended community attributes of the
           route, along with options to modify how the community is
           modified. Extended communities may be set using an inline
           list OR a reference to an existing defined set (but not
           both).";

      container config {
        description
          "Configuration data for the set-ext-community action";

        uses set-ext-community-action-config;
      }

      container state {

        config false;

        description
          "Operational state data for the set-ext-community action";

        uses set-ext-community-action-config;

         uses set-ext-community-action-state;
      } set-community-action-common;
         uses set-ext-community-inline-top;
         uses set-ext-community-reference-top;

       }
     }

     grouping bgp-actions-config bgp-actions-top {
       description
      "Configuration data
         "Top-level grouping for BGP-specific actions";

       container bgp-actions {
         description
           "Top-level container for BGP-specific actions";

         leaf set-route-origin {
           type oc-bgp-types:bgp-origin-attr-type; bgp-types:bgp-origin-attr-type;
           description
             "set the origin attribute to the specified value";
         }

         leaf set-local-pref {
           type uint32;
           description
             "set the local pref attribute on the route update";
         }

         leaf set-next-hop {
           type bgp-next-hop-type;
           description
             "set the next-hop attribute in the route update";
         }

         leaf set-med {
           type bgp-set-med-type;
           description
             "set the med metric attribute in the route update";
         }
  }

  grouping bgp-actions-state {
    description
      "Operational state data for BGP-specific actions";
  }

  grouping bgp-actions-top {
    description
      "Top-level grouping for BGP-specific actions";

    container bgp-actions {
      description
        "Top-level container for BGP-specific actions";

      container config {
        description
          "Configuration data for BGP-specific actions";

        uses bgp-actions-config;
      }

      container state {

        config false;
        description
          "Operational state data for BGP-specific actions";

        uses bgp-actions-config;
        uses bgp-actions-state;
      }
         uses as-path-prepend-top;
         uses set-community-action-top;
         uses set-ext-community-action-top;
       }
     }

     augment "/rpol:routing-policy/rpol:policy-definitions/" +
       "rpol:policy-definition/rpol:statements/rpol:statement/" +
       "rpol:conditions" {
       description
         "BGP policy conditions added to routing policy module";

       uses bgp-conditions-top;
     }
     augment "/rpol:routing-policy/rpol:policy-definitions/" +
       "rpol:policy-definition/rpol:statements/rpol:statement/" +
       "rpol:actions" {
       description "BGP policy actions added to routing policy
       module";

       uses bgp-actions-top;
     }

     // rpc statements

     // notification statements
   }
       <CODE ENDS>

10.  Contributors

   Previous versions of this document saw contributions from Anees
   Shaikh, Rob Shakir, Kevin D'Souza, Alexander Clemm, Aleksandr
   Zhadkin, and Xyfeng Liu.

11.  Acknowledgements

   The authors are grateful for valuable contributions to this document
   and the associated models from: Ebben Aires, Pavan Beeram, Chris
   Chase, Ed Crabbe, Luyuan Fang, Bill Fenner, Akshay Gattani, Josh
   George, Vijay Gill, Matt John, Jeff Haas, Dhanendra Jain, Acee
   Lindem, Ina Minei, Carl Moberg, Ashok Narayanan, Einar Nilsen-
   Nygaard, Adam Simpson, Puneet Sood, Jason Sterne, Jeff Tantsura, Jim
   Uttaro, and Gunter Vandevelde.

12.  References

10.1.

12.1.  Normative references

   [RFC6020]  Bjorklund, M., Ed.,

   [I-D.ietf-rtgwg-ni-model]
              Berger, L., Hopps, C., Lindem, A., Bogdanovic, D., and X.
              Liu, "YANG - A Data Modeling Language Model for
              the Network Configuration Protocol (NETCONF)", Instances", draft-ietf-rtgwg-
              ni-model-12 (work in progress), March 2018.

   [RFC1997]  Chandra, R., Traina, P., and T. Li, "BGP Communities
              Attribute", RFC 1997, DOI 10.17487/RFC1997, August 1996,
              <https://www.rfc-editor.org/info/rfc1997>.

   [RFC2439]  Villamizar, C., Chandra, R., and R. Govindan, "BGP Route
              Flap Damping", RFC 6020, 2439, DOI 10.17487/RFC6020, October 2010,
              <http://www.rfc-editor.org/info/rfc6020>.

   [RFC6241]  Enns, R., Ed., Bjorklund, 10.17487/RFC2439, November
              1998, <https://www.rfc-editor.org/info/rfc2439>.

   [RFC3688]  Mealling, M., Ed., Schoenwaelder, J., Ed.,
              and A. Bierman, Ed., "Network Configuration Protocol
              (NETCONF)", "The IETF XML Registry", BCP 81, RFC 6241, 3688,
              DOI 10.17487/RFC6241, June 2011,
              <http://www.rfc-editor.org/info/rfc6241>. 10.17487/RFC3688, January 2004,
              <https://www.rfc-editor.org/info/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, January 2006,
              <http://www.rfc-editor.org/info/rfc4271>.

   [RFC1997]  Chandra, R., Traina, P., and T. Li, "BGP Communities
              Attribute", RFC 1997, DOI 10.17487/RFC1997, August 1996,
              <http://www.rfc-editor.org/info/rfc1997>.
              <https://www.rfc-editor.org/info/rfc4271>.

   [RFC4456]  Bates, T., Chen, E., and R. Chandra, "BGP Route
              Reflection: An Alternative to Full Mesh Internal BGP
              (IBGP)", RFC 4456, DOI 10.17487/RFC4456, April 2006,
              <http://www.rfc-editor.org/info/rfc4456>.

   [RFC3065]  Traina, P., McPherson, D., and J. Scudder, "Autonomous
              System Confederations for BGP", RFC 3065,
              DOI 10.17487/RFC3065, February 2001,
              <http://www.rfc-editor.org/info/rfc3065>.

   [RFC2439]  Villamizar, C., Chandra, R., and R. Govindan, "BGP Route
              Flap Damping", RFC 2439, DOI 10.17487/RFC2439, November
              1998, <http://www.rfc-editor.org/info/rfc2439>.
              <https://www.rfc-editor.org/info/rfc4456>.

   [RFC4724]  Sangli, S., Chen, E., Fernando, R., Scudder, J., and Y.
              Rekhter, "Graceful Restart Mechanism for BGP", RFC 4724,
              DOI 10.17487/RFC4724, January 2007,
              <http://www.rfc-editor.org/info/rfc4724>.
              <https://www.rfc-editor.org/info/rfc4724>.

   [RFC4760]  Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
              "Multiprotocol Extensions for BGP-4", RFC 4760,
              DOI 10.17487/RFC4760, January 2007,
              <https://www.rfc-editor.org/info/rfc4760>.

   [RFC5065]  Traina, P., McPherson, D., and J. Scudder, "Autonomous
              System Confederations for BGP", RFC 5065,
              DOI 10.17487/RFC5065, August 2007,
              <https://www.rfc-editor.org/info/rfc5065>.

   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246,
              DOI 10.17487/RFC5246, August 2008,
              <https://www.rfc-editor.org/info/rfc5246>.

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

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

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

   [RFC6811]  Mohapatra, P., Scudder, J., Ward, D., Bush, R., and R.
              Austein, "BGP Prefix Origin Validation", RFC 6811,
              DOI 10.17487/RFC6811, January 2013,
              <http://www.rfc-editor.org/info/rfc6811>.

   [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>.
              <https://www.rfc-editor.org/info/rfc6811>.

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

   [RFC3688]  Mealling,
              <https://www.rfc-editor.org/info/rfc6991>.

   [RFC7950]  Bjorklund, M., Ed., "The IETF XML Registry", BCP 81, YANG 1.1 Data Modeling Language",
              RFC 3688, 7950, DOI 10.17487/RFC3688, January 2004,
              <http://www.rfc-editor.org/info/rfc3688>.

10.2.  Informative references

   [I-D.ietf-rtgwg-policy-model]
              Shaikh, A., Shakir, R., D'Souza, K., and C. Chase,
              "Routing Policy Configuration Model for Service Provider
              Networks", draft-ietf-rtgwg-policy-model-01 (work in
              progress), April 2016.

   [I-D.openconfig-netmod-opstate]
              Shakir, R., Shaikh, 10.17487/RFC7950, August 2016,
              <https://www.rfc-editor.org/info/rfc7950>.

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

   [RFC8341]  Bierman, A. and M. Hines, "Consistent Modeling
              of Operational State Data in YANG", draft-openconfig-
              netmod-opstate-01 (work in progress), July 2015.

   [I-D.ietf-netmod-routing-cfg] Bjorklund, "Network Configuration
              Access Control Model", STD 91, RFC 8341,
              DOI 10.17487/RFC8341, March 2018,
              <https://www.rfc-editor.org/info/rfc8341>.

   [RFC8349]  Lhotka, L. and A. L., Lindem, A., and Y. Qu, "A YANG Data Model for
              Routing
              Management", draft-ietf-netmod-routing-cfg-22 (work in
              progress), July 2016.

   [I-D.rtgyangdt-rtgwg-device-model] Management (NMDA Version)", RFC 8349,
              DOI 10.17487/RFC8349, March 2018,
              <https://www.rfc-editor.org/info/rfc8349>.

12.2.  Informative references

   [I-D.ietf-rtgwg-policy-model]
              Qu, Y., Tantsura, J., Lindem, A., Berger, L., Bogdanovic, D., Liu, X., and C. Hopps,
              "Network Device YANG Organizational Models", draft-
              rtgyangdt-rtgwg-device-model-04 (work in progress), May
              2016.

   [I-D.openconfig-rtgwg-network-instance]
              Shakir, R., A. Shaikh,
              "A YANG Data Model for Network Instances in Service
              Provider Networks", draft-openconfig-rtgwg-network-
              instance-01 Routing Policy Management", draft-
              ietf-rtgwg-policy-model-02 (work in progress), November 2015.

   [I-D.talwar-rtgwg-grpc-use-cases]
              Specification, g., Kolhe, March 2018.

   [RFC8342]  Bjorklund, M., Schoenwaelder, J., Shaikh, A., and J. George,
              "Use cases for gRPC in network management", draft-talwar-
              rtgwg-grpc-use-cases-00 (work in progress), July 2016.

Appendix A.  Acknowledgements

   The authors are grateful for valuable contributions to this document
   and the associated models from: Ebben Aires, Pavan Beeram, Chris
   Chase, Ed Crabbe, Luyuan Fang, Bill Fenner, Akshay Gattani, Josh
   George, Vijay Gill, Matt John, Jeff Haas, Dhanendra Jain, Acee
   Lindem, Ina Minei, Carl Moberg, Ashok Narayanan, Einar Nilsen-
   Nygaard, Adam Simpson, Puneet Sood, Jason Sterne, Jeff Tantsura, Jim
   Uttaro, and Gunter Vandevelde.

Appendix B.  Change summary

B.1.  Changes between revisions -01 and -02

   o  Refactored BGP model such that it is comprised of multiple sub-
      modules rather than independent modules.

   o  Remove the need for self-augmentation of the BGP model to allow
      the ability to import the model in wider structures more easily.

   o  Added new operational state values for BGP session established
      transitions and last-established timestamp.  Also deprecated
      uptime operational state leaf.

   o  Added ability to select eligible paths for add-paths based on a
      policy.

B.2.  Changes between revisions -00 Shafer, P., Watsen, K.,
              and -01

   o  Updated module namespaces to reflect IETF standard namespace.

   o  Updated module filenames with ietf- prefix per R. Wilton, "Network Management Datastore Architecture
              (NMDA)", RFC 6087
      guidelines. 8342, DOI 10.17487/RFC8342, March 2018,
              <https://www.rfc-editor.org/info/rfc8342>.

Authors' Addresses

   Anees Shaikh (editor)
   Google
   1600 Amphitheatre Pkwy
   Mountain View, CA  94043
   US

   Email: aashaikh@google.com

   Rob Shakir (editor)
   Jive Communications, Inc.
   1275 West 1600 North, Suite 100
   Orem, UT  84057

   Email: rjs@rob.sh

   Keyur Patel (editor)
   Cisco
   170 W. Tasman Drive
   San Jose,
   Arrcus
   CA  95134
   USA

   Email: keyupate@cisco.com keyur@arrcus.com
   Mahesh Jethanandani

   Email: mjethanandani@gmail.com

   Susan Hares (editor)
   Huawei
   7453 Hickory Hill
   Saline, MI  48176
   USA

   Email: shares@ndzh.com

   Kevin D'Souza
   AT&T
   200 S. Laurel Ave
   Middletown, NJ
   US

   Email: kd6913@att.com

   Deepak Bansal
   Microsoft
   205 108th Ave. NE, Suite 400
   Bellevue, WA
   US

   Email: dbansal@microsoft.com

   Alexander Clemm
   Cisco
   170 W. Tasman Drive
   San Jose, CA  95134
   USA

   Email: alex@cisco.com
   Aleksandr Zhdankin
   Cisco
   170 W. Tasman Drive
   San Jose, CA  95134
   USA

   Email: azhdanki@cisco.com

   Mahesh Jethanandani
   Cisco Systems, Inc
   180 W. Tasman Drive
   San Jose, CA  95134
   USA

   Phone: +1 408.526.8763
   Email: mjethanandani@gmail.com

   Xyfeng Liu
   Ericsson
   1595 Spring Hill Road, Suite 500
   Vienna, VA  22182
   USA

   Email: xufeng.liu@ericsson.com