BESS Working Group                                               D. Jain
Internet-Draft                                                  K. Patel
Intended status: Standards Track                            P. Brissette
Expires: October 27, 2017 April 21, 2018                                            Cisco
                                                                   Z. Li
                                                               S. Zhuang
                                                     Huawei Technologies
                                                                  X. Liu
                                                                   Jabil
                                                                 J. Haas
                                                                S. Esale
                                                        Juniper Networks
                                                                  B. Wen
                                                                 Comcast
                                                          April 25,
                                                        October 18, 2017

                  Yang Data Model for BGP/MPLS L3 VPNs
                   draft-ietf-bess-l3vpn-yang-01.txt
                   draft-ietf-bess-l3vpn-yang-02.txt

Abstract

   This document defines a YANG data model that can be used to configure
   and manage BGP Layer 3 VPNs.

Status of This Memo

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

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   This Internet-Draft will expire on October 27, 2017. April 21, 2018.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Definitions and Acronyms  . . . . . . . . . . . . . . . . . .   3
   3.  Design of BGP L3VPN Data Model  . . . . . . . . . . . . . . .   4
     3.1.  Overview  . . . . . . . . . . . . . . . . . . . . . . . .   4
     3.2.  VRF Specific Configuration  . . . . . . . . . . . . . . .   4
       3.2.1.  VRF interface . . . . . . . . . . . . . . . . . . . .   4
       3.2.2.  Route distinguisher . . . . . . . . . . . . . . . . .   4
       3.2.3.  Import and export route targets . . . . . . . . . . .   5
       3.2.4.  Forwarding mode . . . . . . . . . . . . . . . . . . .   5
       3.2.5.  Label security  . . . . . . . . . . . . . . . . . . .   5
       3.2.6.  Yang tree . . . . . . . . . . . . . . . . . . . . . .   5
     3.3.  BGP Specific Configuration  . . . . . . . . . . . . . . .   7   6
       3.3.1.  VPN peering . . . . . . . . . . . . . . . . . . . . .   7
       3.3.2.  VPN prefix limits . . . . . . . . . . . . . . . . . .   7
       3.3.3.  Label Mode  . . . . . . . . . . . . . . . . . . . . .   8   7
       3.3.4.  ASBR options  . . . . . . . . . . . . . . . . . . . .   8   7
       3.3.5.  Yang tree . . . . . . . . . . . . . . . . . . . . . .   8   7
   4.  BGP Yang Module . . . . . . . . . . . . . . . . . . . . . . .  10   8
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  25  19
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  25  19
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  26  19
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  26  19
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  26  19
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  27  20
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  27  21

1.  Introduction

   YANG [RFC6020] is a data definition language that was introduced to
   define the contents of a conceptual data store that allows networked
   devices to be managed 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 other interfaces, such as CLI and programmatic
   APIs.

   This document defines a YANG model that can be used to configure and
   manage BGP L3VPNs [RFC4364].  It contains VRF sepcific parameters as
   well as BGP specific parameters applicable for L3VPNs.  The
   individual containers defined in this model contain control knobs for
   configuration for that purpose, as well as a few data nodes that can
   be used to monitor health and gather statistics.

1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

2.  Definitions and Acronyms

   AF: Address Family

   AS: Autonomous System

   ASBR: Autonomous System Border Router

   BGP: Border Gateway Protocol

   CE: Customer Edge

   PE: Provider Edge

   L3VPN: Layer 3 VPN

   NETCONF: Network Configuration Protocol

   RD: Route Distinguisher
   ReST: Representational State Transfer, a style of stateless interface
   and protocol that is generally carried over HTTP

   RTFilter: Route Filter

   VPN: Virtual Private Network

   VRF: Virtual Routing and Forwarding

   YANG: Data definition language for NETCONF

3.  Design of BGP L3VPN Data Model

3.1.  Overview

   There are two parts of the BGP L3VPN yang data model.  The first part
   of the model defines VRF specific parameters for L3VPN by augmenting
   the network-instance container defined in the network instance model
   [I-D.ietf-rtgwg-ni-model] and the second part of the model defines
   BGP specific parameters for the L3VPN by augmenting the base BGP data
   model defined in [I-D.ietf-idr-bgp-model].

3.2.  VRF Specific Configuration

   IETF network instance model defines a base identity for network
   instance type as L3-VRF.  For L3VPN, the VRF specific parameters are
   defined by augmenting the network-instance container corresponding various ni-types, one of which is
   l3vpn.  This provides an anchor point to
   L3-VRF instance.  A add a new container l3vpn is added for l3vpn.
   Under this container per VPN parameters. parameters pertaining to L3VPN are
   added.

3.2.1.  VRF interface

   To associate a VRF instance with an interface, the interface bind-network-instance
   config should be defined in the context of network instance representing a L3-VRF. used.  This is covered in the base network instance
   model [I-D.ietf-rtgwg-ni-model].

3.2.2.  Route distinguisher

   Route distinguisher (RD) is an unique identifier used in VPN routes
   to distinguish prefixes across different VPNs.  RD is 8 byte field as
   defined in the [RFC4364].  Where the first two bytes refer to type
   followed by 6 bytes of value.  The format of the value is dependent
   on type.  In the yang model, RDs are defined l3vpn container under
   network-instance.

3.2.3.  Import and export route targets

   Route-target (RT) is an extended community used to specify the rules
   for importing and exporting the routes for each VRF as defined in
   [RFC4364].  This is applicable in the context of an address-family
   under the VRF.  Under the l3vpn container, statements for import and
   export route-targets are added for ipv4 and ipv6 address family.
   Both import and export sets are modeled as a list of rout-targets.
   An import rule is modeled as list of RTs or a policy leafref
   specifying the list of RTs to be matched for importing routes into
   the VRF.  Similarly an export rule is set or RTs or a policy leafref
   specifying the list of RTs which should be attached to routes
   exported from this VRF.  In the case where policy is used to specify
   the RTs, a reference to the policy via leafref is used in this model,
   but actual definition of policy is outside the scope of this
   document.  In addition, this section also defines parameters for the
   import from global routing table and export to global routing table,
   as well as route limit per VPN instance for ipv4 and ipv6 address
   family.

3.2.4.  Forwarding mode

   This configuration augments interface list under interface container
   under a network instance as defined in IETF network instance model
   [I-D.ietf-rtgwg-ni-model].  Forwarding mode configuration is required
   under the ASBR facing interface to enable mpls forwarding for
   directly connected BGP peers for inter-as option B peering.

3.2.5.  Label security

   For inter-as option-B peering across ASs, under the ASBR facing
   interface, mpls label security enables the checks for RPF label on
   incoming packets.  Ietf-interface container is augmented to add this
   config.

3.2.6.  Yang tree
module: ietf-bgp-l3vpn
  augment /ni:network-instances/ni:network-instance: /ni:network-instances/ni:network-instance/ni:ni-type:
    +--:(l3vpn)
       +--rw l3vpn
          +--rw route-distinguisher
         |  +--rw config
         |  |  +--rw rd?   rt-types:route-distinguisher
         |  +--ro state
         |        union
          +--ro rd? auto-rd?   rt-types:route-distinguisher
          +--rw ipv4
          |  +--rw unicast
          |     +--rw route-targets
         |     |  +--rw config
         | vpn-targets
          |     |  +--rw rts* [rt]
         | vpn-target* [route-target]
          |     |  |  +--rw rt route-target         rt-types:route-target
          |     |  |  |  +--rw rt-type?   enumeration
         | route-target-type    rt-types:route-target-type
          |     |  +--rw route-policy?   string
          |     |  +--ro state
         |     |     +--ro rts* [rt]
         |     |     |  +--ro rt         rt-types:route-target
         |     |     |  +--ro rt-type?   enumeration
         |     |     +--ro route-policy?   string
         |     +--rw import-from-global
          |     |  +--rw config
         |     |  |  +--rw enable?             boolean
          |     |  |  +--rw advertise-as-vpn?   boolean
          |     |  |  +--rw route-policy?       string
          |     |  |  +--rw bgp-valid-route?    boolean
          |     |  |  +--rw protocol?           enumeration
          |     |  |  +--rw instance?           string
          |     |  +--ro state
         |     |     +--ro enable?             boolean
         |     |     +--ro advertise-as-vpn?   boolean
         |     |     +--ro route-policy?       string
         |     |     +--ro bgp-valid-route?    boolean
         |     |     +--ro protocol?           enumeration
         |     |     +--ro instance?           string
         |     +--rw export-to-global
          |     |  +--rw config
         |     |  |  +--rw enable?   boolean
         |     |  +--ro state
         |     |     +--ro enable?   boolean
          |     +--rw routing-table-limit
          |     |  +--rw config
         |     |  |  +--rw routing-table-limit-number?   uint32
          |     |  |  +--rw (routing-table-limit-action)?
          |     |  |     +--:(enable-alert-percent)
          |     |     |     |  +--rw alert-percent-value?          uint8
         |          rt-types:percentage
          |     |     +--:(enable-simple-alert)
          |     |  |        +--rw simple-alert?                 boolean
          |     |  +--ro state
         |     |     +--ro routing-table-limit-number?   uint32
         |     |     +--ro (routing-table-limit-action)?
         |     |        +--:(enable-alert-percent)
         |     |        |  +--ro alert-percent-value?          uint8
         |     |        +--:(enable-simple-alert)
         |     |           +--ro simple-alert?                 boolean
         |     +--rw tunnel-params
          |        +--rw config
         |        |  +--rw tunnel-policy?   string
         |        +--ro state
         |           +--ro tunnel-policy?   string

  augment /if:interfaces/if:interface:
    +--rw forwarding-mode
      |  +--rw config
      |  |  +--rw forwarding-mode?   fwd-mode-type
      |  +--ro state
      |     +--ro forwarding-mode?   fwd-mode-type       enumeration
    +--rw mpls-label-security
       +--rw config
         |  +--rw rpf?   boolean
         +--ro state
            +--ro rpf?   boolean

3.3.  BGP Specific Configuration

   The BGP specific configuration for L3VPNs is defined by augmenting
   base BGP model [I-D.ietf-idr-bgp-model].  In particular, specific
   knobs are added under neighbor and address family containers to
   handle VPN routes and ASBR peering.

3.3.1.  VPN peering

   For Peering between PE routers, specific VPN address family needs to
   be enabled under BGP container in the default routing-instance. context of core instance.  Base
   BGP draft [I-D.ietf-idr-bgp-model] has l3vpn address family in the
   list of identity refs for AFs under global and neighbor modes.  The
   same is augmented here for additional knobs.  For peering with CE
   routers the VRF specific BGP configurations such as neighbors and
   address-family are covered in base BGP config, except that such
   configuration will be in the context of a VRF.  The instance of BGP
   in this case would be a separate instance in the context of routing
   instance realizing a VRF.

3.3.2.  VPN vrf-root
   as defined in [I-D.ietf-rtgwg-ni-model].

3.3.2.  VPN prefix limits

   Limits for max number of VPN prefixes for a PE router is defined in
   the context of VPN address family under BGP.  This would be the total
   number of prefixes in VPN table per AF in the context of BGP
   protocol.  Route table limit for ipv4 and ipv6 address family for
   each VPN instance is also defined under BGP.  The total prefix limit
   per VPN, including all the protocols is defined in the context of VRF
   address family under routing instance.

3.3.3.  Label Mode

   Label mode knobs control the label allocation behavior for VRF
   routes.  Such as to specify Per-site, Per-vpn and Per-route label
   allocation.  These knobs augment BGP global AF containers in the
   context of default routing instance.

3.3.4.  ASBR options

   This includes few specific knobs for ASBR peering methods illustrated
   in [RFC4364].  Such as route target retention on ASBRs and rewrite
   next hop to self, for inter-as
   VPN peering across ASBRs with option-B method.  Similarly next hop unchanged on ASBRs for option-C peering.  Appropriate address-
   family containers under BGP AF and NBR modes base model are augmented for
   these parameters.  As a note, when a knob is applicable for neighbor,
   it is also defined under corresponding peer-group container. this.

3.3.5.  Yang tree
module: ietf-bgp-l3vpn
  augment /bgp:bgp/bgp:global/bgp:afi-safis
           /bgp:afi-safi/bgp:l3vpn-ipv4-unicast:
      +--rw retain-rts /bgp:bgp/bgp:global/bgp:afi-safis/bgp:afi-safi/bgp:l3vpn-ipv4-unicast:
    +--rw config retain-route-targets
    |  +--rw all?            empty
    |  +--rw route-policy?   string
         +--ro state
            +--ro all?            empty
            +--ro route-policy?   string
    +--rw prefix-limit
         +--rw config
         | vpn-prefix-limit
       +--rw prefix-limit-number?   uint32
         |
       +--rw (prefix-limit-action)?
         |
          +--:(enable-alert-percent)
          |     |  +--rw alert-percent-value?   uint8
         |   rt-types:percentage
          |  +--rw route-unchanged?       boolean
         |
          +--:(enable-simple-alert)
         |
             +--rw simple-alert?          boolean
         +--ro state
            +--ro prefix-limit-number?   uint32
            +--ro (prefix-limit-action)?
               +--:(enable-alert-percent)
               |  +--ro alert-percent-value?   uint8
               |  +--ro route-unchanged?       boolean
               +--:(enable-simple-alert)
                  +--ro simple-alert?          boolean       ...

  augment /bgp:bgp/bgp:global/bgp:afi-safis
           /bgp:afi-safi/bgp:ipv4-unicast:
      +--rw config
      | /bgp:bgp/bgp:global/bgp:afi-safis/bgp:afi-safi/bgp:ipv4-unicast:
    +--rw label-mode?            bgp-label-mode
      +--ro state
         +--ro label-mode?   bgp-label-mode
    +--rw routing-table-limit
       +--rw config
         |  +--rw routing-table-limit-number?   uint32
         |
       +--rw (routing-table-limit-action)?
         |
          +--:(enable-alert-percent)
          |     |  +--rw alert-percent-value?          uint8
         |          rt-types:percentage
          +--:(enable-simple-alert)
         |
             +--rw simple-alert?                 boolean
         +--ro state
            +--ro routing-table-limit-number?   uint32
            +--ro (routing-table-limit-action)?
               +--:(enable-alert-percent)
               |  +--ro alert-percent-value?          uint8
               +--:(enable-simple-alert)
                  +--ro simple-alert?                 boolean
         ...

   augment /bgp:bgp/bgp:neighbors/bgp:neighbor:
      +--rw nexthop-options
         +--rw config
         |  +--rw next-hop-self?        boolean
         |  +--rw next-hop-unchanged?   boolean
         +--rw state
            +--rw next-hop-self?        boolean
            +--rw next-hop-unchanged?   boolean

   augment /bgp:bgp/bgp:peer-groups/bgp:peer-group:
      +--rw nexthop-options
         +--rw config
         |  +--rw next-hop-self?        boolean
         |  +--rw next-hop-unchanged?   boolean
         +--rw state
            +--rw next-hop-self?        boolean
            +--rw next-hop-unchanged?   boolean

   augment /bgp:bgp/bgp:neighbors/bgp:neighbor
           /bgp:afi-safis/bgp:afi-safi:
      +--rw nexthop-options
         +--rw config
         |  +--rw next-hop-self?        boolean
         |  +--rw next-hop-unchanged?   boolean
         +--rw state
            +--rw next-hop-self?        boolean
            +--rw next-hop-unchanged?   boolean

   augment /bgp:bgp/bgp:peer-groups/bgp:peer-group
           /bgp:afi-safis/bgp:afi-safi:
      +--rw nexthop-options
         +--rw config
         |  +--rw next-hop-self?        boolean
         |  +--rw next-hop-unchanged?   boolean
         +--rw state
            +--rw next-hop-self?        boolean
            +--rw next-hop-unchanged?   boolean

4.  BGP Yang Module

<CODE BEGINS> file "ietf-bgp-l3vpn@2017-04-25.yang" "ietf-bgp-l3vpn@2017-10-18.yang"

module ietf-bgp-l3vpn {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-bgp-l3vpn";
  // replace with IANA namespace when assigned
  prefix l3vpn ;

  import ietf-network-instance {
    prefix ni;
    //revision-date 2016-06-23;
    revision-date 2017-09-27;
  }

  import ietf-routing-types {
    prefix rt-types;
    //revision-date 2017-02-27;
    revision-date 2017-10-13;
  }

  import ietf-interfaces {
    prefix if;

  }

  import ietf-bgp {
    prefix bgp;
    //revision-date
    revision-date 2016-06-21;
  }

  organization
     "IETF BGP Enabled Services WG";

  contact
     "BESS working group - bess@ietf.org";

  description
    "This YANG module defines a YANG data model to configure and
     manage BGP Layer3 VPNs. It augments the IETF bgp yang model
     and IETF network instance model to add L3VPN specific
     configuration and operational knobs.

     Terms and Acronyms

     AF : Address Family

     AS : Autonomous System

     ASBR : Autonomous Systems Border Router

     BGP (bgp) : Border Gateway Protocol

     CE  : Customer Edge

     IP (ip) : Internet Protocol

     IPv4 (ipv4):Internet Protocol Version 4

     IPv6 (ipv6): Internet Protocol Version 6

     L3VPN: Layer 3 VPN

     PE : Provider Edge

     RT : Route Target

     RD : Route Distinguisher

     VPN : Virtual Private Network
     VRF : Virtual Routing and Forwarding

    ";

  revision 2017-10-18 {
    description
      "Removed state containers per NMDA aligntment" +
      "Changes for network instance ni-type alignment" +
      "Other cleanups";
    reference "";
  }
  revision 2017-04-25 {
    description
      "Reused ietf-roting-types.yang for vpn route-targets" +
      " and route distinguisher types";
    reference "";
  }

  revision 2016-09-09 {
    description
      "Initial revision.";
    reference
      "RFC XXXX: A YANG Data Model for BGP L3VPN config management";
  }

  //RD
  grouping route-distinguisher-params {
    description "BGP route distinguisher";
    container route-distinguisher {
      description "Route distinguisher value as per RFC4364";
        container config {
          description
            "Configuration parameters for route distinguisher";
          leaf rd {
            type rt-types:route-distinguisher;
            description "Route distinguisher value as per RFC4364";
          }
        }
        container state {
          config "false" ;
          description
            "State information for route distinguisher";
          leaf rd {
            type rt-types:route-distinguisher;
            description "Route distinguisher value";
          }
        }
     }
  }

  //Label mode
  typedef bgp-label-mode {
    type enumeration {
      enum per-ce {
        description "Allocate labels per CE";
      }
      enum per-route {
        description "Allocate labels per prefix";
      }
      enum per-vpn {
        description "Allocate labels per VRF";
      }
    }
    description "BGP label allocation mode";
  }

  //Fwding mode
  typedef fwd-mode-type

  //RD
  grouping route-distinguisher-params {
    description "Route distinguisher value as per RFC4364";
    leaf rd {
      type enumeration union {
      enum mpls
        // Either RD value as per IETF routing types or AUTO assigned value
        type rt-types:route-distinguisher;
        type enumeration {
          enum auto-assigned {
            description "Forwarding mode mpls"; "Assigned by system";
          }
        }
      }
      description
      "Enable forwarding mode under ASBR facing interface"; "Route distinguisher value as per RFC4364";
    }

  grouping forwarding-mode
    leaf auto-rd {
      type rt-types:route-distinguisher;
      config false;
      description "Forwarding
        "Automatically assigned RD value when rd AUTO is configured";
    }
  }

  //Fwding mode of interface for ASBR scenario";
    container
  grouping forwarding-mode {
    description "Forwarding mode of interface for ASBR scenario";
      container config {
        description "Configuration of Forwarding mode";
    leaf forwarding-mode {
      type  fwd-mode-type; enumeration {
        enum mpls {
          description "Forwarding mode for this interface"; mpls";
        }
      }
      container state {
        config "false";
        description "State information of Forwarding mode";
        leaf forwarding-mode {
        type  fwd-mode-type;
      description "Forwarding mode of interface for this interface";
        }
      } ASBR scenario";
    }
  }

  grouping label-security {
    description "Mpls label security for ASBR option B scenario";
    container mpls-label-security {
      description "MPLS label secruity";
      container config {
        description "Configuration parameters";
      leaf rpf {
        type boolean;
        description "Enable MPLS label security rpf on interface";
      }
    }
      container state {
        config "false";
        description "State information";
        leaf rpf {
          type boolean;
          description "MPLS label security rpf on interface";
        }
      }
    }
  }

  //per VPN instance table limit under BGP
  grouping prefix-limit  vpn-pfx-limit {
    description "Per VPN instance table limit under BGP";
    container vpn-prefix-limit {
      description
       "The prefix limit command config sets a limit on the maximum
        number of prefixes supported in the existing VPN
        instance, preventing the PE from importing excessive
        VPN route prefixes.
       ";

      leaf prefix-limit-number {
        type uint32 {
          range "1..4294967295";
        }
        description
             "Specifies the maximum number of prefixes supported in the
              VPN instance IPv4 or IPv6 address family.";
      }

      choice prefix-limit-action {
        description ".";
        case enable-alert-percent {
          leaf alert-percent-value {
             type uint8 {
             range "1..100";
           } rt-types:percentage;
             description
               "Specifies the proportion of the alarm threshold to the
                maximum number of prefixes.";
          }
          leaf route-unchanged {
             type boolean;
             default "false";
             description
                 "Indicates that the routing table remains unchanged.
                  By default, route-unchanged is not configured. When
                  the number of prefixes in the routing table is
                  greater than the value of the parameter number,
                  routes are processed as follows:
                  (1)If route-unchanged is configured, routes in the
                     routing table remain unchanged.
                  (2)If route-unchanged is not configured, all routes
                     in the routing table are deleted and then
                     re-added.";
        }
      }
      case enable-simple-alert {
        leaf simple-alert {
          type boolean;
          default "false";
          description
                 "Indicates that when the number of VPN route prefixes
                  exceeds number, prefixes can still join the VPN
                  routing table and alarms are displayed.";
        }
      }
    }
  }

  grouping  vpn-pfx-limit {
    description "Per VPN instance table limit under BGP";
    container vpn-prefix-limit {
      description "Prefix limit for this table";
      container config {
         description "Config parameters";
         uses prefix-limit;
      }
      container state {
         config "false";
         description "State parameters";
         uses prefix-limit;
      }
    }
  }

  grouping route-target-set {
    description
      "Extended community route-target set ";
    list rts {
      key "rt" ;
      description
         "List of route-targets" ;
      leaf rt {
        type rt-types:route-target;
        description "Route target extended community as per RFC4360";

      }
      leaf rt-type {
        type enumeration {
          enum import {
            description "Route target is for import routes";
          }
          enum export {
            description "Route target is for export routes";
          }
          enum both {
            description
              "Route target as follows:
                  (1)If route-unchanged is for both import configured, routes in the
                     routing table remain unchanged.
                  (2)If route-unchanged is not configured, all routes
                     in the routing table are deleted and export routes";
          }
        }
        description "Route target type"; then
                     re-added.";
          }
        }
        case enable-simple-alert {
          leaf route-policy simple-alert {
            type string; boolean;
            default "false";
            description
         "Reference to
                 "Indicates that when the policy containing set number of routes.
          TBD: leafref to policy entry in IETF policy model"; VPN route prefixes
                  exceeds number, prefixes can still join the VPN
                  routing table and alarms are displayed.";
          }
        }
      }

    }
  }

  grouping import-from-gbl global-imports {
      description "Grouping for imports from global routing table";
    container import-from-global {
      description "Import from global routing table";
      leaf enable {
        type boolean;
        description "Enable";
      }
      leaf advertise-as-vpn {
        type boolean;
        description
          "Advertise routes imported from global table as VPN routes";
      }
      leaf route-policy {
        type string;
        description "Route policy as filter for importing routes";
      }

      leaf bgp-valid-route {
        type boolean;
        description
          "Enable all valid routes (including non-best paths) to be
           candidate for import";
      }

      leaf protocol {
        type enumeration {
          enum ALL {
            value "0";
            description "ALL:";
          }
          enum Direct {
            value "1";
            description "Direct:";
          }
          enum OSPF {
            value "2";
            description "OSPF:";
          }
          enum ISIS {
            value "3";
            description "ISIS:";
          }
          enum Static {
            value "4";
            description "Static:";
          }
          enum RIP {
            value "5";
            description "RIP:";
          }
          enum BGP {
            value "6";
            description "BGP:";
          }
          enum OSPFV3 {
            value "7";
            description "OSPFV3:";
          }
          enum RIPNG {
            value "8";
            description "RIPNG:";
          }
        }
        description
          "Specifies the protocol from which routes are imported.
           At present, In the IPv4 unicast address family view,
           the protocol can be IS-IS,static, IS-IS, static, direct and BGP.";
      }

      leaf instance {
        type string;
        description
             "Specifies the instance id of the protocol";
      }
    }
  grouping global-imports {
      description "Grouping for imports from global routing table";
    container import-from-global {
      description "Import from global routing table";
      container config {
          description "Configuration";
          uses import-from-gbl;
      }
      container state {
          config "false";
          description "State";
          uses import-from-gbl;
      }
    }
  }

  grouping export-to-gbl {
    description "Export routes to default VRF";
    leaf enable {
      type boolean;
        description "Enable";
    }
  }

  grouping global-exports {
    description "Grouping for exports routes to global table";
    container export-to-global {
      description "Export to global routing table";
      container config {
         description "Configuration";
         uses export-to-gbl;
      }
      container state
      leaf enable {
        config "false";
        type boolean;
          description "State";
        uses export-to-gbl; "Enable";
      }
    }
  }

  grouping route-target-params {
    description "Grouping to specify rules for route import and export";
    container route-targets vpn-targets {
      description
        "Set of route-targets to match for import and export routes
         to/from VRF";
      container config {
         description
               "Configuration of route targets";
      uses route-target-set ;
      }
      container state rt-types:vpn-route-targets;
      leaf route-policy {
        config "false" ;
        type string;
        description
               "State information for
          "Reference to the route targets";
           uses route-target-set ; policy containing set of route-targets.
           TBD: leafref to policy xpath in IETF route policy model";
       }
    }
  }

  grouping route-tbl-limit-params {
    description "Grouping for VPN table prefix limit config";
    leaf routing-table-limit-number {
      type uint32 {
        range "1..4294967295";
      }
      description
        "Specifies the maximum number of routes supported by a
         VPN instance. ";
    }

    choice routing-table-limit-action {
      description ".";
      case enable-alert-percent {
        leaf alert-percent-value {
          type uint8 {
                 range "1..100";
               } rt-types:percentage;
          description
            "Specifies the percentage of the maximum number of
             routes. When the maximum number of routes that join
             the VPN instance is up to the value
             (number*alert-percent)/100, the system prompts
             alarms. The VPN routes can be still added to the
             routing table, but after the number of routes
             reaches number, the subsequent routes are
             dropped.";
        }
      }
      case enable-simple-alert {
        leaf simple-alert {
          type boolean;
          description
            "Indicates that when VPN routes exceed number, routes
             can still be added into the routing table, but the
             system prompts alarms.
             However, after the total number of VPN routes and
             network public routes reaches the unicast route limit
             specified in the License, the subsequent VPN routes
             are dropped.";
        }
      }
    }
  }

  grouping routing-tbl-limit {
    description ".";
    container routing-table-limit {
      description
        "The routing-table limit command sets a limit on the maximum
         number of routes that the IPv4 or IPv6 address family of a
         VPN instance can support.
         By default, there is no limit on the maximum number of
         routes that the IPv4 or IPv6 address family of a VPN
         instance can support, but the total number of private
         network and public network routes on a device cannot
         exceed the allowed maximum number of unicast routes.";
          container config {
             description "Config parameters";
             uses route-tbl-limit-params;
          }
          container state {
              config "false";
              description "State parameters";

         uses route-tbl-limit-params;
    }
 }
   }

  // Tunnel policy parameters
  grouping tunnel-params {
     description "Tunnel parameters";
     container tunnel-params {
        description "Tunnel config parameters";
        container config {
           description "configuration parameters";
           leaf tunnel-policy {
              type string;
              description
                  "Tunnel policy to steer the VPN traffic into specific tunnel";

           }
        } parameters
  grouping tunnel-params {
    description "Tunnel parameters";
    container state tunnel-params {
           config "false";
      description "state "Tunnel config parameters";
      leaf tunnel-policy {
        type string;
        description
          "Tunnel policy to steer the VPN traffic into specific tunnel";
      }
    }
  }
  }

  // Grouping for the L3vpn specific parameters under VRF
  // (network-instance)
  grouping l3vpn-vrf-params {
    description "Specify route filtering rules for import/export";
    container ipv4 {
      description
        "Specify route filtering rules for import/export";
      container unicast {
        description
          "Specify route filtering rules for import/export";
        uses route-target-params;
        uses global-imports;
        uses global-exports;
        uses routing-tbl-limit;
        uses tunnel-params;
      }
    }
    container ipv6 {
      description
        "Ipv6 address family specific rules for import/export";
      container unicast {
        description "Ipv6 unicast address family";
        uses route-target-params;
        uses global-imports;
        uses global-exports;
        uses routing-tbl-limit;
        uses tunnel-params;
      }
    }
  }

  grouping bgp-label-mode {
    description "MPLS/VPN label allocation mode";
       container config {
         description
           "Configuration parameters for label allocation mode";
         leaf label-mode {
           type bgp-label-mode;
           description "Label allocation mode";
         }
       }
       container state {
         config "false" ;
         description "State information for label allocation mode";
    leaf label-mode {
      type bgp-label-mode;
      description "Label allocation mode";
    }
  }
  }

  grouping retain-route-targets {
    description "Grouping for route target accept";
    container retain-route-targets {
      description "Control route target acceptance behavior for ASBRs";
      container config {
         description
           "Configuration parameters for retaining route targets";
      leaf all {
        type empty;
        description "Disable filtering of all route-targets";
      }
      leaf route-policy {
        type string;
        description "Filter routes as per filter policy name
                     TBD: leafref to IETF routing policy model";
      }
    }
      container state {
         config "false" ;
         description "State information for retaining route targets";
         leaf all {
            type empty;
            description "Disable filtering of all route-targets";
         }
         leaf route-policy {
            type string;
            description "Filter routes as per filter policy name";
         }
      }
    }
  }
  grouping nexthop-opts {
     description "Next hop control options for inter-as route exchange";
     leaf next-hop-self {
        type boolean;
        description
          "Set nexthop of the route to self when advertising routes";
     }
     leaf next-hop-unchanged {
        type boolean;
        description "Enforce no nexthop change when advertising routes";
     }
  }

  grouping asbr-nexthop-options {
     description "Nexthop parameters for inter-as VPN options ";
     container nexthop-options {
         description "Nexthop related options for inter-as options";
         container config {
             description "Configuration parameters for nexthop options";
             uses nexthop-opts;
         }
         container state {
             config "false";
             description "State information for nexthop options" ;
             uses nexthop-opts;
         }
     }
  }

  //
  // VRF specific parameters.
  // RD and RTs and route import-export rules are added under
  // network instance container in network instance model, hence
  // per VRF scoped
  augment "/ni:network-instances/ni:network-instance" "/ni:network-instances/ni:network-instance/ni:ni-type" {
    description
      "Augment network instance for per VRF L3vpn parameters";
     container
    case l3vpn {
        //Enable this check once network instance model has
        //identify defined for VRF type
        //when "../type='rt:vrf-network-instance'" {
        //  description
        //    "This
      container is only valid for vrf routing instance.";
        //} l3vpn {
        description "Configuration of L3VPN specific parameters";

        uses route-distinguisher-params;
        uses l3vpn-vrf-params ;
      }
    }
  }

  // bgp mpls forwarding enable required for inter-as option AB.
  augment "/if:interfaces/if:interface" {
    description
      "BGP mpls forwarding mode configuration on interface for
       ASBR scenario";
    uses forwarding-mode ;
    uses label-security;
  }

  //
  // BGP Specific Paramters
  //

  //
  // Retain route-target for inter-as option ASBR knob.
  // vpn prefix limits
  // vpnv4/vpnv6 address-family only.
  augment "/bgp:bgp/bgp:global/bgp:afi-safis/" +
          "bgp:afi-safi/bgp:l3vpn-ipv4-unicast" {
    description "Retain route targets for ASBR scenario";
    uses retain-route-targets;
    uses vpn-pfx-limit;
  }

  augment "/bgp:bgp/bgp:global/bgp:afi-safis/" +
          "bgp:afi-safi/bgp:l3vpn-ipv6-unicast" {
    description "Retain route targets for ASBR scenario";
    uses retain-route-targets;
    uses vpn-pfx-limit;
  }

  // Label allocation mode configuration. Certain AFs only.
  augment "/bgp:bgp/bgp:global/bgp:afi-safis/" +
          "bgp:afi-safi/bgp:ipv4-unicast" {

    description
      "Augment BGP global AF mode for label allocation mode
       configuration";
     uses bgp-label-mode ;
     uses routing-tbl-limit;
  }

  augment "/bgp:bgp/bgp:global/bgp:afi-safis/" +
          "bgp:afi-safi/bgp:ipv6-unicast" {
    description
      "Augment BGP global AF mode for label allocation mode
       configuration";
     uses bgp-label-mode ;
     uses routing-tbl-limit;
  }

  // Nexthop options for the inter-as ASBR peering.
  augment "/bgp:bgp/bgp:neighbors/bgp:neighbor" {
     description
       "Augment BGP NBR mode with nexthop options for inter-as ASBRs";
     uses asbr-nexthop-options;
  }

  augment "/bgp:bgp/bgp:peer-groups/bgp:peer-group" {
     description
       "Augment BGP peer-group mode with nexthop options for inter-as
        ASBRs";
     uses asbr-nexthop-options;
  }

  augment "/bgp:bgp/bgp:neighbors/bgp:neighbor/" +
          "bgp:afi-safis/bgp:afi-safi" {
     description
       "Augment BGP NBR AF mode with nexthop options for inter-as
        ASBRs";
     uses asbr-nexthop-options;
  }

  augment "/bgp:bgp/bgp:peer-groups/bgp:peer-group/" +
          "bgp:afi-safis/bgp:afi-safi" {
     description
       "Augment BGP peer-group AF mode with nexthop options for inter-as
        ASBRs";
     uses asbr-nexthop-options;
  }
}

<CODE ENDS>

5.  IANA Considerations

6.  Security Considerations

   The transport protocol used for sending the BGP L3VPN data MUST
   support authentication and SHOULD support encryption.  The data-model
   by itself does not create any security implications.

   This draft does not change any underlying security issues inherent in
   [I-D.ietf-rtgwg-ni-model] and [I-D.ietf-idr-bgp-model].

7.  Acknowledgements

   The authors would like to thank TBD for their detail reviews and
   comments.

8.  References

8.1.  Normative References

   [I-D.ietf-idr-bgp-model]
              Shaikh, A., Shakir, R., Patel, K., Hares, S., D'Souza, K.,
              Bansal, D., Clemm, A., Zhdankin, A., Jethanandani, M., and
              X. Liu, "BGP Model for Service Provider Networks", draft-
              ietf-idr-bgp-model-02 (work in progress), July 2016.

   [I-D.ietf-rtgwg-ni-model]
              Berger, L., Hopps, C., Lindem, A., and D. Bogdanovic,
              "Network Instance Model", draft-ietf-rtgwg-ni-model-00 D., and X.
              Liu, "YANG Network Instances", draft-ietf-rtgwg-ni-
              model-04 (work in progress), June 2016. September 2017.

   [I-D.ietf-rtgwg-routing-types]
              Liu, X., Qu, Y., Lindem, A., Hopps, C., and L. Berger,
              "Routing Area Common YANG Data Types", draft-ietf-rtgwg-
              routing-types-02
              routing-types-17 (work in progress), March October 2017.

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

   [RFC4364]  Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
              Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February
              2006, <http://www.rfc-editor.org/info/rfc4364>. <https://www.rfc-editor.org/info/rfc4364>.

   [RFC6020]  Bjorklund, M., Ed., "YANG - A Data Modeling Language for
              the Network Configuration Protocol (NETCONF)", RFC 6020,
              DOI 10.17487/RFC6020, October 2010,
              <http://www.rfc-editor.org/info/rfc6020>.
              <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,
              <http://www.rfc-editor.org/info/rfc6241>.
              <https://www.rfc-editor.org/info/rfc6241>.

8.2.  Informative References

   [RFC2547]  Rosen, E. and Y. Rekhter, "BGP/MPLS VPNs", RFC 2547,
              DOI 10.17487/RFC2547, March 1999,
              <http://www.rfc-editor.org/info/rfc2547>.
              <https://www.rfc-editor.org/info/rfc2547>.

   [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>.
              <https://www.rfc-editor.org/info/rfc4271>.

   [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/rfc4760>.

Authors' Addresses

   Dhanendra Jain
   Cisco
   170 W. Tasman Drive
   San Jose, CA  95134
   USA

   Email: dhjain@cisco.com

   Keyur Patel
   Cisco
   170 W. Tasman Drive
   San Jose, CA  95134
   USA

   Email: keyur@arrcus.com

   Patrice Brissette
   Cisco
   170 W. Tasman Drive
   San Jose, CA  95134
   USA

   Email: pbrisset@cisco.com

   Zhenbin Li
   Huawei Technologies
   Huawei Bld., No.156 Beiqing Rd.
   Beijing  100095
   China

   Email: lizhenbin@huawei.com

   Shunwan Zhuang
   Huawei Technologies
   Huawei Bld., No.156 Beiqing Rd.
   Beijing  100095
   China

   Email: zhuangshunwan@huawei.com
   Xufeng Liu
   Jabil
   8281 Greensboro Drive, Suite 200
   McLean, VA  22102
   USA

   Email: Xufeng_Liu@jabil.com

   Jeffrey Haas
   Juniper Networks

   Email: jhaas@juniper.net

   Santosh Esale
   Juniper Networks
   1194 N. Mathilda Ave.
   Sunnyvale, CA  94089
   US

   Email: sesale@juniper.net

   Bin Wen
   Comcast

   Email: Bin_Wen@cable.comcast.com