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Versions: (draft-liu-rtgwg-yang-vrrp) 00 01 02 03 04 05 06 07 08 09 10 11

Network Working Group                                        X. Liu, Ed.
Internet-Draft                                               A. Kyparlis
Intended status: Standards Track                                   Jabil
Expires: August 26, 2018                                       R. Parikh
                                                                  VMware
                                                               A. Lindem
                                                           Cisco Systems
                                                                M. Zhang
                                                     Huawei Technologies
                                                       February 22, 2018


    A YANG Data Model for Virtual Router Redundancy Protocol (VRRP)
                     draft-ietf-rtgwg-yang-vrrp-11

Abstract

   This document describes a data model for Virtual Router Redundancy
   Protocol (VRRP).  Both version 2 and version 3 of VRRP are covered.

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/.

   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 August 26, 2018.

Copyright Notice

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

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must



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   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.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   2
     1.2.  Tree Diagrams . . . . . . . . . . . . . . . . . . . . . .   3
     1.3.  Prefixes in Data Node Names . . . . . . . . . . . . . . .   3
   2.  Design of the Data Model  . . . . . . . . . . . . . . . . . .   3
     2.1.  Scope of the Model  . . . . . . . . . . . . . . . . . . .   3
     2.2.  Relations with Interface Model and IP Model . . . . . . .   4
     2.3.  Protocol Configuration  . . . . . . . . . . . . . . . . .   5
     2.4.  Protocol States . . . . . . . . . . . . . . . . . . . . .   6
     2.5.  Notifications . . . . . . . . . . . . . . . . . . . . . .   8
   3.  Tree Structure  . . . . . . . . . . . . . . . . . . . . . . .  10
   4.  YANG Module . . . . . . . . . . . . . . . . . . . . . . . . .  12
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  34
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  35
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  36
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  36
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  38
   Appendix A.  Data Tree Example  . . . . . . . . . . . . . . . . .  39
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  42

1.  Introduction

   This document introduces a YANG [RFC6020][RFC7950] data model for
   Virtual Router Redundancy Protocol (VRRP) [RFC3768] [RFC5798].  VRRP
   provides higher resiliency by specifying an election protocol that
   dynamically assigns responsibility for a virtual router to one of the
   VRRP routers on a LAN.

   This YANG model supports both version 2 and version 3 of VRRP.  VRRP
   version 2 defined in [RFC3768] supports IPv4.  VRRP version 3 defined
   in [RFC5798] supports both IPv4 and IPv6.

1.1.  Terminology

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

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

   o  augment



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   o  data model

   o  data node

1.2.  Tree Diagrams

   A simplified graphical representation of the data model is used in
   this document.  The meaning of the symbols in these diagrams is
   defined in [I-D.ietf-netmod-yang-tree-diagrams].

1.3.  Prefixes in Data Node Names

   In this document, names of data nodes, actions, and other data model
   objects are often used without a prefix, as long as it is clear from
   the context in which YANG module each name is defined.  Otherwise,
   names are prefixed using the standard prefix associated with the
   corresponding YANG module, as shown in Table 1.

        +--------+-----------------+------------------------------+
        | Prefix | YANG module     | Reference                    |
        +--------+-----------------+------------------------------+
        | yang   | ietf-yang-types | [RFC6991]                    |
        | inet   | ietf-inet-types | [RFC6991]                    |
        | if     | ietf-interfaces | [I-D.ietf-netmod-rfc7223bis] |
        | ip     | ietf-ip         | [I-D.ietf-netmod-rfc7277bis] |
        +--------+-----------------+------------------------------+

             Table 1: Prefixes and Corresponding YANG Modules

2.  Design of the Data Model

2.1.  Scope of the Model

   The model covers VRRP version 2 [RFC3768] and VRRP version 3
   [RFC5798] protocols.  The model is designed to be implemented on a
   device where VRRP version 2 or version 3 is implemented.  With the
   help of a proper management protocol, the defined model can be used
   to:

   o  Configure the VRRP version 2 or version 3 protocol.

   o  Manage the protocol operational behavior.

   o  Retrieve the protocol operational status.

   o  Receive the protocol notifications.





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2.2.  Relations with Interface Model and IP Model

   This model augments the interface data model "ietf-interfaces"
   [I-D.ietf-netmod-rfc7223bis] and the IP management model "ietf-ip"
   [I-D.ietf-netmod-rfc7277bis].  The augmentation relations are shown
   as follows:


   module: ietf-interfaces
      +--rw interfaces
         +--rw interface* [name]
               ...
            +--rw ip:ipv4!
            |  +--rw ip:address* [ip]
                     ...
            |  +--rw vrrp:vrrp
            |     +--rw vrrp:vrrp-instance* [vrid]
            |        +--rw vrrp:vrid                            uint8
            |        +--rw vrrp:virtual-ipv4-addresses
                           ...
            +--rw ip:ipv6!
               +--rw ip:address* [ip]
                     ...
               +--rw vrrp:vrrp
                  +--rw vrrp:vrrp-instance* [vrid]
                     +--rw vrrp:vrid                            uint8
                     +--rw vrrp:virtual-ipv6-addresses
                           ...


   In the above figure, a tree node without a prefix is from the model
   "ietf-interfaces".  A tree node with prefix "ip:" is from the model
   "ietf-ip".  A tree node with prefix "vrrp:" is from the VRRP model
   specified in this document.

   The "vrrp" container contains a list of vrrp-instance nodes, which
   are instantiated under an interface for a specified address family
   (IPv4 or IPv6).

   Each vrrp-instance node represents a VRRP router state machine
   described in Section 6.4 of [RFC5798], providing the configuration
   and state information for the election process of a virtual router.
   The IP addresses on the augmented interface are the real addresses
   through which the VRRP router operates.  The IPv4 or IPv6 address(es)
   associated with a virtual router (described in Section 1 of
   [RFC5798]) are modeled as a list of IPv4 or IPv6 addresses under the
   vrrp-instance.




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2.3.  Protocol Configuration

   The model structure for the protocol configuration is as shown below:


     augment /if:interfaces/if:interface/ip:ipv4:
       +--rw vrrp
          +--rw vrrp-instance* [vrid]
             +--rw vrid                            uint8
             |     ...
             +--rw track
             |  +--rw interfaces
             |  |  +--rw interface* [interface]
             |  |     +--rw interface             if:interface-ref
             |  |           ...
             |  +--rw networks
             |     +--rw network* [prefix]
             |        +--rw prefix                inet:ipv4-prefix
             |              ...
             +--rw virtual-ipv4-addresses
                +--rw virtual-ipv4-address* [ipv4-address]
                   +--rw ipv4-address    inet:ipv4-address

     augment /if:interfaces/if:interface/ip:ipv6:
       +--rw vrrp
          +--rw vrrp-instance* [vrid]
             +--rw vrid                            uint8
             |     ...
             +--rw track
             |  +--rw interfaces
             |  |  +--rw interface* [interface]
             |  |     +--rw interface             if:interface-ref
             |  |           ...
             |  +--rw networks
             |     +--rw network* [prefix]
             |        +--rw prefix                inet:ipv6-prefix
             |              ...
             +--rw virtual-ipv6-addresses
                +--rw virtual-ipv6-address* [ipv6-address]
                   +--rw ipv6-address    inet:ipv6-address


   The model allows to configure the following protocol entities:

   o  VRRP instance (version 2 or version 3), representing a VRRP
      router.

   o  Virtual IPv4 or IPv6 address associated with a virtual router.



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   o  Tracking interface, to detect interface connectivity failures.

   o  Tracking network, to detect interface connectivity failures.

2.4.  Protocol States

   The model structure for the protocol states is as shown below:


   module: ietf-vrrp
       +--ro vrrp
          |     // global operational states
          +--ro virtual-routers?   uint32
          +--ro interfaces?        uint32
          +--ro statistics                 // global statistics
             +--ro discontinuity-datetime?   yang:date-and-time
             +--ro checksum-errors?          yang:counter64
             +--ro version-errors?           yang:counter64
             +--ro vrid-errors?              yang:counter64
             +--ro ip-ttl-errors?            yang:counter64

     augment /if:interfaces/if:interface/ip:ipv4:
       +--rw vrrp
          +--rw vrrp-instance* [vrid]
             +--rw vrid                            uint8
             |     ...
             +--rw track
             |  +--rw interfaces
             |  |  +--rw interface* [interface]
             |  |     +--rw interface             if:interface-ref
             |  |           ...
             |  +--rw networks
             |     +--rw network* [prefix]
             |        +--rw prefix                inet:ipv4-prefix
             |              ...
             +--rw virtual-ipv4-addresses
             |  +--rw virtual-ipv4-address* [ipv4-address]
             |     +--rw ipv4-address    inet:ipv4-address
             |
             |     // per instance operational states
             +--ro state?                         identityref
             +--ro is-owner?                      boolean
             +--ro last-adv-source?               inet:ip-address
             +--ro up-datetime?                   yang:date-and-time
             +--ro master-down-interval?          uint32
             +--ro skew-time?                     uint32
             +--ro last-event?                    identityref
             +--ro new-master-reason?             new-master-reason-type



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             +--ro statistics                // per instance statistics
                +--ro discontinuity-datetime?    yang:date-and-time
                +--ro master-transitions?        yang:counter32
                +--ro advertisement-recv?        yang:counter64
                +--ro advertisement-sent?        yang:counter64
                +--ro interval-errors?           yang:counter64
                |       {validate-interval-errors}?
                +--ro priority-zero-pkts-rcvd?   yang:counter64
                +--ro priority-zero-pkts-sent?   yang:counter64
                +--ro invalid-type-pkts-rcvd?    yang:counter64
                +--ro address-list-errors?       yang:counter64
                |       {validate-address-list-errors}?
                +--ro packet-length-errors?      yang:counter64

     augment /if:interfaces/if:interface/ip:ipv6:
       +--rw vrrp
          +--rw vrrp-instance* [vrid]
             +--rw vrid                            uint8
             +     ...
             +--rw track
             |  +--rw interfaces
             |  |  +--rw interface* [interface]
             |  |     +--rw interface             if:interface-ref
             |  |           ...
             |  +--rw networks
             |     +--rw network* [prefix]
             |        +--rw prefix                inet:ipv6-prefix
             |              ...
             +--rw virtual-ipv6-addresses
             |  +--rw virtual-ipv6-address* [ipv6-address]
             |     +--rw ipv6-address    inet:ipv6-address
             |
             |     // per instance operational states
             +--ro state?                         identityref
             +--ro is-owner?                      boolean
             +--ro last-adv-source?               inet:ip-address
             +--ro up-datetime?                   yang:date-and-time
             +--ro master-down-interval?          uint32
             +--ro skew-time?                     uint32
             +--ro last-event?                    identityref
             +--ro new-master-reason?             new-master-reason-type
             +--ro statistics                // per instance statistics
                +--ro discontinuity-datetime?    yang:date-and-time
                +--ro master-transitions?        yang:counter32
                +--ro advertisement-recv?        yang:counter64
                +--ro advertisement-sent?        yang:counter64
                +--ro interval-errors?           yang:counter64
                |       {validate-interval-errors}?



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                +--ro priority-zero-pkts-rcvd?   yang:counter64
                +--ro priority-zero-pkts-sent?   yang:counter64
                +--ro invalid-type-pkts-rcvd?    yang:counter64
                +--ro address-list-errors?       yang:counter64
                |       {validate-address-list-errors}?
                +--ro packet-length-errors?      yang:counter64


   This model conforms to the Network Management Datastore Architecture
   (NMDA) [I-D.ietf-netmod-revised-datastores].  The operational state
   data is combined with the associated configuration data in the same
   hierarchy [I-D.ietf-netmod-rfc6087bis].  When protocol states are
   retrieved from the NMDA operational state datastore, the returned
   states cover all "config true" (rw) and "config false" (ro) nodes
   defined in the schema.

   The model allows to retrieve protocol states at the following levels:

   o  VRRP instance (version 2 or version 3), representing a VRRP
      router.

   o  Virtual IPv4 or IPv6 address associated with a virtual router.

   o  Tracking interface, to detect interface connectivity failures.

   o  Tracking network, to detect interface connectivity failures.

   o  Global states and statistics summarizing all instances.

2.5.  Notifications

   This model defines the following VRRP specific notifications:



















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   notifications:
      +---n vrrp-new-master-event
      |  +--ro master-ip-address    inet:ip-address
      |  +--ro new-master-reason    new-master-reason-type
      +---n vrrp-protocol-error-event
      |  +--ro protocol-error-reason    identityref
      +---n vrrp-virtual-router-error-event
         +--ro interface                      if:interface-ref
         +--ro (ip-version)
         |  +--:(ipv4)
         |  |  +--ro ipv4
         |  |     +--ro vrid    leafref
         |  +--:(ipv6)
         |     +--ro ipv6
         |        +--ro vrid    leafref
         +--ro virtual-router-error-reason    identityref


   Each notification type is used to indicate a type of VRRP state
   changes or error occurances:

   vrrp-new-master-event
      VRRP new master event, indicating that a new master has been
      elected.

   vrrp-protocol-error-event
      VRRP protocol error event for a message that fails to reach a VRRP
      instance to be processed.

   vrrp-virtual-router-error-event
      VRRP virtual router error event for a message processed on a VRRP
      instance.

   In addition to the notifications specified above, the mechanism
   defined in [I-D.ietf-netconf-subscribed-notifications] and
   [I-D.ietf-netconf-yang-push] can be used for other general
   notifications.  This mechanism currently allows the user to:

   o  Subscribe notifications on a per client basis.

   o  Specify subtree filters or xpath filters so that only interested
      contents will be sent.

   o  Specify either periodic or on-demand notifications.







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3.  Tree Structure

   The VRRP YANG data model defined in this document has the following
   tree structure:

   module: ietf-vrrp
       +--ro vrrp
          +--ro virtual-routers?   uint32
          +--ro interfaces?        uint32
          +--ro statistics
             +--ro discontinuity-datetime?   yang:date-and-time
             +--ro checksum-errors?          yang:counter64
             +--ro version-errors?           yang:counter64
             +--ro vrid-errors?              yang:counter64
             +--ro ip-ttl-errors?            yang:counter64
     augment /if:interfaces/if:interface/ip:ipv4:
       +--rw vrrp
          +--rw vrrp-instance* [vrid]
             +--rw vrid                            uint8
             +--rw version                         identityref
             +--rw log-state-change?               boolean
             +--rw preempt
             |  +--rw enabled?     boolean
             |  +--rw hold-time?   uint16
             +--rw priority?                       uint8
             +--rw accept-mode?                    boolean
             +--rw (advertise-interval-choice)?
             |  +--:(v2)
             |  |  +--rw advertise-interval-sec?         uint8
             |  +--:(v3)
             |     +--rw advertise-interval-centi-sec?   uint16
             +--rw track
             |  +--rw interfaces
             |  |  +--rw interface* [interface]
             |  |     +--rw interface             if:interface-ref
             |  |     +--rw priority-decrement?   uint8
             |  +--rw networks
             |     +--rw network* [prefix]
             |        +--rw prefix                inet:ipv4-prefix
             |        +--rw priority-decrement?   uint8
             +--rw virtual-ipv4-addresses
             |  +--rw virtual-ipv4-address* [ipv4-address]
             |     +--rw ipv4-address    inet:ipv4-address
             +--ro state?                          identityref
             +--ro is-owner?                       boolean
             +--ro last-adv-source?                inet:ip-address
             +--ro up-datetime?                    yang:date-and-time
             +--ro master-down-interval?           uint32



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             +--ro skew-time?                      uint32
             +--ro last-event?                     identityref
             +--ro new-master-reason?
    new-master-reason-type
             +--ro statistics
                +--ro discontinuity-datetime?    yang:date-and-time
                +--ro master-transitions?        yang:counter32
                +--ro advertisement-recv?        yang:counter64
                +--ro advertisement-sent?        yang:counter64
                +--ro interval-errors?           yang:counter64
                |       {validate-interval-errors}?
                +--ro priority-zero-pkts-rcvd?   yang:counter64
                +--ro priority-zero-pkts-sent?   yang:counter64
                +--ro invalid-type-pkts-rcvd?    yang:counter64
                +--ro address-list-errors?       yang:counter64
                |       {validate-address-list-errors}?
                +--ro packet-length-errors?      yang:counter64
     augment /if:interfaces/if:interface/ip:ipv6:
       +--rw vrrp
          +--rw vrrp-instance* [vrid]
             +--rw vrid                            uint8
             +--rw version                         identityref
             +--rw log-state-change?               boolean
             +--rw preempt
             |  +--rw enabled?     boolean
             |  +--rw hold-time?   uint16
             +--rw priority?                       uint8
             +--rw accept-mode?                    boolean
             +--rw advertise-interval-centi-sec?   uint16
             +--rw track
             |  +--rw interfaces
             |  |  +--rw interface* [interface]
             |  |     +--rw interface             if:interface-ref
             |  |     +--rw priority-decrement?   uint8
             |  +--rw networks
             |     +--rw network* [prefix]
             |        +--rw prefix                inet:ipv6-prefix
             |        +--rw priority-decrement?   uint8
             +--rw virtual-ipv6-addresses
             |  +--rw virtual-ipv6-address* [ipv6-address]
             |     +--rw ipv6-address    inet:ipv6-address
             +--ro state?                          identityref
             +--ro is-owner?                       boolean
             +--ro last-adv-source?                inet:ip-address
             +--ro up-datetime?                    yang:date-and-time
             +--ro master-down-interval?           uint32
             +--ro skew-time?                      uint32
             +--ro last-event?                     identityref



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             +--ro new-master-reason?
    new-master-reason-type
             +--ro statistics
                +--ro discontinuity-datetime?    yang:date-and-time
                +--ro master-transitions?        yang:counter32
                +--ro advertisement-recv?        yang:counter64
                +--ro advertisement-sent?        yang:counter64
                +--ro interval-errors?           yang:counter64
                |       {validate-interval-errors}?
                +--ro priority-zero-pkts-rcvd?   yang:counter64
                +--ro priority-zero-pkts-sent?   yang:counter64
                +--ro invalid-type-pkts-rcvd?    yang:counter64
                +--ro address-list-errors?       yang:counter64
                |       {validate-address-list-errors}?
                +--ro packet-length-errors?      yang:counter64

     notifications:
       +---n vrrp-new-master-event
       |  +--ro master-ip-address    inet:ip-address
       |  +--ro new-master-reason    new-master-reason-type
       +---n vrrp-protocol-error-event
       |  +--ro protocol-error-reason    identityref
       +---n vrrp-virtual-router-error-event
          +--ro interface                      if:interface-ref
          +--ro (ip-version)
          |  +--:(ipv4)
          |  |  +--ro ipv4
          |  |     +--ro vrid    leafref
          |  +--:(ipv6)
          |     +--ro ipv6
          |        +--ro vrid    leafref
          +--ro virtual-router-error-reason    identityref

4.  YANG Module

   This module references [RFC2787], [RFC3768], [RFC5798] and [RFC6527].


   <CODE BEGINS> file "ietf-vrrp@2018-01-09.yang"
   module ietf-vrrp {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-vrrp";
     prefix "vrrp";

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




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

     import ietf-interfaces {
       prefix "if";
     }

     import ietf-ip {
       prefix "ip";
     }

     organization
       "IETF Routing Area Working Group (RTGWG)";
     contact
       "WG Web:   <https://datatracker.ietf.org/wg/rtgwg/>
        WG List:  <mailto:rtgwg@ietf.org>

        Editor:   Xufeng Liu
                  <mailto:Xufeng_Liu@jabil.com>

        Editor:   Athanasios Kyparlis
                  <mailto:Athanasios_Kyparlis@jabil.com>

        Editor:   Ravi Parikh
                  <mailto:parikhr@vmware.com>

        Editor:   Acee Lindem
                  <mailto:acee@cisco.com>

        Editor:   Mingui Zhang
                  <mailto:zhangmingui@huawei.com>";

     description
       "This YANG module defines a model for managing Virtual Router
        Redundancy Protocol (VRRP) version 2 and version 3.

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

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

        This version of this YANG module is part of RFC XXXX; see the



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        RFC itself for full legal notices.";

     revision 2018-01-09 {
       description "Initial revision";
       reference
         "RFC XXXX: A YANG Data Model for Virtual Router Redundancy
          Protocol (VRRP).
          RFC 2787: Definitions of Managed Objects for the Virtual
          Router Redundancy Protocol.
          RFC 3768: Virtual Router Redundancy Protocol (VRRP).
          RFC 5798: Virtual Router Redundancy Protocol (VRRP) Version 3.
          RFC 6527: Definitions of Managed Objects for the Virtual
          Router Redundancy Protocol Version 3 (VRRPv3).";
     }

     /*
      * Features
      */

     feature validate-interval-errors {
       description
         "This feature indicates that the system validates that
          the advertisement interval from advertisement packets
          received is the same as the one configured for the local
          VRRP router.";
     }

     feature validate-address-list-errors {
       description
         "This feature indicates that the system validates that
          the address list from received packets matches the
          locally configured list for the VRRP router.";
     }

     /*
      * Typedefs
      */

     typedef new-master-reason-type {
       type enumeration {
         enum not-master {
           description
             "The virtual router has never transitioned to master
              state,";
         }
         enum priority {
           description "Priority was higher.";
         }



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         enum preempted {
           description "The master was preempted.";
         }
         enum no-response {
           description "Previous master did not respond.";
         }
       }
       description
         "The reason for the virtual router to transition to master
          state.";
     } // new-master-reason-type

     /*
      * Identities
      */

     /* vrrp-event-type identity and its derivatives. */
     identity vrrp-event-type {
       description
         "The type to indicate the type of a VRRP protocol event.";
     }
     identity vrrp-event-none {
       base vrrp-event-type;
       description
         "Indicates a non-meaningful event.";
     }
     identity vrrp-event-startup {
       base vrrp-event-type;
       description
         "Indicates that a VRRP router has initiated the protocol.";
     }
     identity vrrp-event-shutdown {
       base vrrp-event-type;
       description
         "Indicates that a VRRP router has closed down the protocol.";
     }
     identity vrrp-event-higher-priority-backup {
       base vrrp-event-type;
       description
         "Indicates that a backup router has a higher priority than
          the current master.";
     }
     identity vrrp-event-master-timeout {
       base vrrp-event-type;
       description
         "Indicates that the current master has not sent an
          advertisement within the limit of master-down-interval.";
     }



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     identity vrrp-event-interface-up {
       base vrrp-event-type;
       description
         "Indicates that the VRRP enabled interface has become
          operational up.";
     }
     identity vrrp-event-interface-down {
       base vrrp-event-type;
       description
         "Indicates that the VRRP enabled interface has become
          operational down.";
     }
     identity vrrp-event-no-primary-ip-address {
       base vrrp-event-type;
       description
         "Indicates that the primary IP address on the VRRP enabled
          interface has become unavailable.";
     }
     identity vrrp-event-primary-ip-address {
       base vrrp-event-type;
       description
         "Indicates that the primary IP address on the VRRP enabled
          interface has become available.";
     }
     identity vrrp-event-no-virtual-ip-addresses {
       base vrrp-event-type;
       description
         "Indicates that there are no virtual IP addresses on the
          virtual router.";
     }
     identity vrrp-event-virtual-ip-addresses {
       base vrrp-event-type;
       description
         "Indicates that there are virtual IP addresses on the
          virtual router.";
     }
     identity vrrp-event-preempt-hold-timeout {
       base vrrp-event-type;
       description
         "Indicates that the configured preemption hold time has
          passed.";
     }
     identity vrrp-event-lower-priority-master {
       base vrrp-event-type;
       description
         "Indicates that there is a lower priority VRRP master.";
     }
     identity vrrp-event-owner-preempt {



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       base vrrp-event-type;
       description
         "Indicates that the owner has preempted another router to
          become the master.";
     }

     /* vrrp-error-global identity and its derivatives. */
     identity vrrp-error-global {
       description
         "The type to indicate the type of a VRRP error that occurs
          for a packet before it reaches a VRRP router.";
     }
     identity checksum-error {
       base vrrp-error-global;
       description
         "A packet has been received with an invalid VRRP checksum
          value.";
     }
     identity ip-ttl-error {
       base vrrp-error-global;
       description
         "A packet has been received with IP TTL (Time-To-Live)
          not equal to 255.";
     }
     identity version-error {
       base vrrp-error-global;
       description
         "A packet has been received with an unknown or unsupported
          version number.";
     }
     identity vrid-error {
       base vrrp-error-global;
       description
         "A packet has been received with a VRID that is not valid
          for any virtual router on this router.";
     }

     /* vrrp-error-virtual-router identity and its derivatives. */
     identity vrrp-error-virtual-router {
       description
         "The type to indicate the type of a VRRP error that occurs
          after a packet reaches a VRRP router.";
     }
     identity address-list-error {
       base vrrp-error-virtual-router;
       description
         "A packet has been received with an address list that
          does not match the locally configured address list for



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          the virtual router.";
     }
     identity interval-error {
       base vrrp-error-virtual-router;
       description
         "A packet has been received with an advertisement
          interval different than the one configured for the local
          virtual router";
     }
     identity packet-length-error {
       base vrrp-error-virtual-router;
       description
         "A packet has been received with a packet length less
          than the length of the VRRP header.";
     }

     /* vrrp-state-type identity and its derivatives. */
     identity vrrp-state-type {
       description
         "The type to indicate the state of a virtual router.";
     }
     identity initialize {
       base vrrp-state-type;
       description
         "Indicates that the virtual router is waiting
          for a startup event.";
     }
     identity backup {
       base vrrp-state-type;
       description
         "Indicates that the virtual router is monitoring the
          availability of the master router.";
     }
     identity master {
       base vrrp-state-type;
       description
         "Indicates that the virtual router is forwarding
          packets for IP addresses that are associated with
          this virtual router.";
     }

     /* vrrp-version identity and its derivatives. */
     identity vrrp-version {
       description
         "The version of the VRRP protocol.";
     }
     identity vrrp-v2 {
       base vrrp-version;



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       description
         "Indicates version 2 of the VRRP protocol.";
     }
     identity vrrp-v3 {
       base vrrp-version;
       description
         "Indicates version 3 of the VRRP protocol.";
     }

     /*
      * Groupings
      */

     grouping vrrp-common-attributes {
       description
         "Group of VRRP attributes common to version 2 and version 3";

       leaf vrid {
         type uint8 {
           range 1..255;
         }
         description "Virtual router ID.";
       }

       leaf version {
         type identityref {
           base vrrp:vrrp-version;
         }
         mandatory true;
         description "Version 2 or version 3 of VRRP.";
       }

       leaf log-state-change {
         type boolean;
         default "false";
         description
           "Generates VRRP state change messages each time the VRRP
            instance changes state (from up to down or down to up).";
       }

       container preempt {
         description
           "Enables a higher priority Virtual Router Redundancy
            Protocol (VRRP) backup router to preempt a lower priority
            VRRP master.";
         leaf enabled {
           type boolean;
           default "true";



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           description
             "'true' if preemption is enabled.";
         }
         leaf hold-time {
           type uint16;
           units seconds;
           default 0;
           description
             "Hold time, in seconds, for which a higher priority VRRP
              backup router must wait before preempting a lower priority
              VRRP master.";
         }
       }

       leaf priority {
         type uint8 {
           range 1..254;
         }
         default 100;
         description
           "Configures the Virtual Router Redundancy Protocol (VRRP)
            election priority for the backup virtual router.";
       }

       leaf accept-mode {
         when "derived-from-or-self(current()/../version, 'vrrp-v3')" {
           description "Applicable only to version 3.";
         }
         type boolean;
         default "false";
         description
           "Controls whether a virtual router in Master state will
            accept packets addressed to the address owner's IPvX address
            as its own if it is not the IPvX address owner. The default
            is false. Deployments that rely on, for example, pinging the
            address owner's IPvX address may wish to configure
            accept-mode to true.

            Note: IPv6 Neighbor Solicitations and Neighbor
            Advertisements MUST NOT be dropped when accept-mode is
            false.";
       }
     } // vrrp-common-attributes

     grouping vrrp-ipv4-attributes {
       description
         "Group of VRRP attributes for IPv4.";




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       uses vrrp-common-attributes;

       choice advertise-interval-choice {
         description
           "The options for the advertisement interval at which VRRPv2
            or VRRPv3 advertisements are sent from the specified
            interface.";

         case v2 {
           when "derived-from-or-self(version, 'vrrp-v2')" {
             description "Applicable only to version 2.";
           }
           leaf advertise-interval-sec {
             type uint8 {
               range 1..254;
             }
             units seconds;
             default 1;
             description
               "Configures the interval that Virtual Router
                Redundancy Protocol Version 2 (VRRPv2) advertisements
                are sent from the specified interface.";
           }
         }

         case v3 {
           when "derived-from-or-self(version, 'vrrp-v3')" {
             description "Applicable only to version 3.";
           }
           leaf advertise-interval-centi-sec {
             type uint16 {
               range 1..4095;
             }
             units centiseconds;
             default 100;
             description
               "Configures the interval that Virtual Router
                Redundancy Protocol version 3 (VRRPv3) advertisements
                are sent from the specified interface.";
           }
         }
       } // advertise-interval-choice

       container track {
         description
           "Enables the specified VRRP instance to track interfaces
            or networks.";
         container interfaces {



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           description
             "Enables the specified Virtual Router Redundancy Protocol
              version 2 (VRRP) or version 3 (VRRPv3) instance to track
              interfaces.
              Interface tracking prevents traffic loss by detecting the
              availability of interfaces. The operational states of
              other interfaces are associated with the priority of a
              VRRP router. When a tracked interface becomes unavailable
              (or operational down), the priority of the backup router
              decrements. When an unavailable interface becomes
              available again, the priority of the backup VRRP router is
              incremented by the same amount.";

           list interface {
             key "interface";
             description
               "Interface to track.";

             leaf interface {
               type if:interface-ref;
               must "/if:interfaces/if:interface[if:name=current()]/"
                  + "ip:ipv4" {
                 description "Interface is IPv4.";
               }
               description
                 "Interface to track.";
             }

             leaf priority-decrement {
               type uint8 {
                 range 1..254;
               }
               default 10;
               description
                 "Specifies how much to decrement the priority of the
                  VRRP instance if the interface goes down.";
             }
           } // interface
         } // interfaces

         container networks {
           description
             "Enables the backup Virtual Router Redundancy Protocol
              version 2 (VRRP) or version 3 (VRRPv3) router to track
              specified networks through the IP network prefixes of
              these networks.
              Network tracking prevents traffic loss by detecting
              network connectivity failure. The states of connectivity



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              to some networks are associated with the priority of a
              VRRP router. When connectivity to a tracked network
              represented by its prefix is lost, the priority of the
              backup VRRP router decrements. When an unavailable network
              is again reachable, the priority of the backup VRRP router
              is incremented by the same amount.";
           list network {
             key "prefix";
             description
               "Enables the specified Virtual Router Redundancy
                Protocol version 2 (VRRP) or version 3 (VRRPv3)
                instance to track an IP network, by specifying the
                prefix of the IP network.";

             leaf prefix {
               type inet:ipv4-prefix;
               description
                 "The prefix of the network to track.";
             }

             leaf priority-decrement {
               type uint8 {
                 range 1..254;
               }
               default 10;
               description
                 "Specifies how much to decrement the priority of the
                  backup VRRP router if there is a failure in the IP
                  network.";
             }
           } // track-network
         } // track-networks
       } // track

       container virtual-ipv4-addresses {
         description
           "Configures the virtual IP address for the Virtual Router
            Redundancy Protocol (VRRP) interface.";

         list virtual-ipv4-address {
           key "ipv4-address";
           max-elements 16;
           description
             "Virtual IP addresses for a single VRRP instance. For a
              VRRP owner router, the virtual address must match one
              of the IP addresses configured on the interface
              corresponding to the virtual router.";




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           leaf ipv4-address {
             type inet:ipv4-address;
             description
               "An IPv4 address associated with a virtual router.";
             reference
               "RFC 5798: Virtual Router Redundancy Protocol (VRRP)
                Version 3. Section 1.2.";
           }
         } // virtual-ipv4-address
       } // virtual-ipv4-addresses
     } // grouping vrrp-ipv4-attributes

     grouping vrrp-ipv6-attributes {
       description
         "Group of VRRP attributes for IPv6.";

       uses vrrp-common-attributes;

       leaf advertise-interval-centi-sec {
         type uint16 {
           range 1..4095;
         }
         units centiseconds;
         default 100;
         description
           "Configures the interval that Virtual Router
            Redundancy Protocol version 3 (VRRPv3) advertisements
            are sent from the specified interface.";
       }

       container track {
         description
           "Enables the specified VRRP instance to track interfaces
            or networks.";
         container interfaces {
           description
             "Enables the specified Virtual Router Redundancy Protocol
              version 2 (VRRP) or version 3 (VRRPv3) instance to track
              interfaces.
              Interface tracking prevents traffic loss by detecting the
              availability of interfaces. The operational states of
              other interfaces are associated with the priority of a
              VRRP router. When a tracked interface becomes unavailable
              (or operational down), the priority of the backup router
              decrements. When an unavailable interface becomes
              available again, the priority of the backup VRRP router is
              incremented by the same amount.";
           list interface {



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             key "interface";
             description
               "Interface to track.";

             leaf interface {
               type if:interface-ref;
               must "/if:interfaces/if:interface[if:name=current()]/"
                  + "ip:ipv6" {
                 description "Interface is IPv6.";
               }
               description
                 "Interface to track.";
             }

             leaf priority-decrement {
               type uint8 {
                 range 1..254;
               }
               default 10;
               description
                 "Specifies how much to decrement the priority of the
                  VRRP instance if the interface goes down.";
             }
           } // interface
         } // interfaces

         container networks {
           description
             "Enables the backup Virtual Router Redundancy Protocol
              version 2 (VRRP) or version 3 (VRRPv3) router to track
              specified networks through the IP network prefixes of
              these networks.
              Network tracking prevents traffic loss by detecting
              network connectivity failure. The states of connectivity
              to some networks are associated with the priority of a
              VRRP router. When connectivity to a tracked network
              represented by its prefix is lost, the priority of the
              backup VRRP router decrements. When an unavailable network
              is again reachable, the priority of the backup VRRP router
              is incremented by the same amount.";
           list network {
             key "prefix";
             description
               "Enables the specified Virtual Router Redundancy
                Protocol version 2 (VRRP) or version 3 (VRRPv3)
                instance to track an IP network, by specifying the
                prefix of the IP network.";




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             leaf prefix {
               type inet:ipv6-prefix;
               description
                 "The prefix of the network to track.";
             }

             leaf priority-decrement {
               type uint8 {
                 range 1..254;
               }
               default 10;
               description
                 "Specifies how much to decrement the priority of the
                  backup VRRP router if there is a failure in the IP
                  network.";
             }
           } // track-network
         } // track-networks
       } // track

       container virtual-ipv6-addresses {
         description
           "Configures the virtual IP address for the Virtual Router
            Redundancy Protocol (VRRP) interface.";
         list virtual-ipv6-address {
           key "ipv6-address";
           max-elements 2;
           description
             "Two IPv6 addresses are allowed. The first one must be
              a link-local address and the second one can be a
              link-local or global address.";

           leaf ipv6-address {
             type inet:ipv6-address;
             description
               "An IPv6 address associated with a virtual router.";
             reference
               "RFC 5798: Virtual Router Redundancy Protocol (VRRP)
                Version 3. Section 1.3.";
           }
         } // virtual-ipv6-address
       } // virtual-ipv6-addresses
     } // grouping vrrp-ipv6-attributes

     grouping vrrp-state-attributes {
       description
         "Group of VRRP state attributes.";




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       leaf state {
         type identityref {
           base vrrp:vrrp-state-type;
         }
         config false;
         description
           "Operational state.";
       }

       leaf is-owner {
         type boolean;
         config false;
         description
           "Set to true if this virtual router is owner.";
       }

       leaf last-adv-source {
         type inet:ip-address;
         config false;
         description
           "Last advertised IPv4/IPv6 source address";
       }

       leaf up-datetime {
         type yang:date-and-time;
         config false;
         description
           "The date and time when this virtual router
            transitioned out of init state.";
       }

       leaf master-down-interval {
         type uint32;
         units centiseconds;
         config false;
         description
           "Time interval for backup virtual router to declare
            Master down.";
       }

       leaf skew-time {
         type uint32;
         units microseconds;
         config false;
         description
           "Calculated based on the priority and advertisement
            interval configuration command parameters. See RFC 3768.";
       }



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       leaf last-event {
         type identityref {
           base vrrp:vrrp-event-type;
         }
         config false;
         description
           "Last reported event.";
       }

       leaf new-master-reason {
         type new-master-reason-type;
         config false;
         description
           "Indicates the reason for the virtual router to transition
            to master state.";
       }

       container statistics {
         config false;
         description
           "VRRP statistics.";

         leaf discontinuity-datetime {
           type yang:date-and-time;
           description
             "The time on the most recent occasion at which any one or
              more of the VRRP statistic counters suffered a
              discontinuity.  If no such discontinuities have occurred
              since the last re-initialization of the local management
              subsystem, then this node contains the time that the
              local management subsystem re-initialized itself.";
         }

         leaf master-transitions {
           type yang:counter32;
           description
             "The total number of times that this virtual router's
              state has transitioned to master";
         }

         leaf advertisement-recv {
           type yang:counter64;
           description
             "The total number of VRRP advertisements received by
              this virtual router.";
         }

         leaf advertisement-sent {



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           type yang:counter64;
           description
             "The total number of VRRP advertisements sent by
              this virtual router.";
         }

         leaf interval-errors {
           if-feature validate-interval-errors;
           type yang:counter64;
           description
             "The total number of VRRP advertisement packets
              received with an advertisement interval
              different than the one configured for the local
              virtual router";
         }

         leaf priority-zero-pkts-rcvd {
           type yang:counter64;
           description
             "The total number of VRRP packets received by the
              virtual router with a priority of 0.";
         }

         leaf priority-zero-pkts-sent {
           type yang:counter64;
           description
             "The total number of VRRP packets sent by the
              virtual router with a priority of 0.";
         }

         leaf invalid-type-pkts-rcvd {
           type yang:counter64;
           description
             "The number of VRRP packets received by the virtual
              router with an invalid value in the 'type' field.";
         }

         leaf address-list-errors {
           if-feature validate-address-list-errors;
           type yang:counter64;
           description
             "The total number of packets received with an
              address list that does not match the locally
              configured address list for the virtual router.";
         }

         leaf packet-length-errors {
           type yang:counter64;



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           description
             "The total number of packets received with a packet
              length less than the length of the VRRP header.";
         }
       } // container statistics
     } // grouping vrrp-state-attributes

     grouping vrrp-global-state-attributes {
       description
         "Group of VRRP global state attributes.";

       leaf virtual-routers {
         type uint32;
         description "Number of configured virtual routers.";
       }

       leaf interfaces {
         type uint32;
         description "Number of interface with VRRP configured.";
       }

       container statistics {
         description
           "VRRP global statistics.";

         leaf discontinuity-datetime {
           type yang:date-and-time;
           description
             "The time on the most recent occasion at which one of
              checksum-errors, version-errors, vrid-errors, and
              ip-ttl-errors suffered a discontinuity.

              If no such discontinuities have occurred since the last
              re-initialization of the local management subsystem,
              then this node contains the time that the local management
              subsystem re-initialized itself.";
         }

         leaf checksum-errors {
           type yang:counter64;
           description
             "The total number of VRRP packets received with an invalid
              VRRP checksum value.";
           reference "RFC 5798, Section 5.2.8";
         }

         leaf version-errors {
           type yang:counter64;



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           description
             "The total number of VRRP packets received with an unknown
              or unsupported version number.";
           reference "RFC 5798, Section 5.2.1";
         }

         leaf vrid-errors {
           type yang:counter64;
           description
             "The total number of VRRP packets received with a VRID that
              is not valid for any virtual router on this router.";
           reference "RFC 5798, Section 5.2.3";
         }

         leaf ip-ttl-errors {
           type yang:counter64;
           description
             "The total number of VRRP packets received by the
              virtual router with IP TTL (Time-To-Live) not equal
              to 255.";
           reference "RFC 5798, Sections 5.1.1.3 and 5.1.2.3.";
         }
       } // statistics
     } // vrrp-global-state-attributes

     /*
      * Configuration data and operational state data nodes
      */

     augment "/if:interfaces/if:interface/ip:ipv4" {
       description "Augment IPv4 interface.";

       container vrrp {
         description
           "Configures the Virtual Router Redundancy Protocol (VRRP)
            version 2 or version 3 for IPv4.";

         list vrrp-instance {
           key "vrid";
           description
             "Defines a virtual router, identified by a virtual router
              identifier (VRID), within IPv4 address space.";

           uses vrrp-ipv4-attributes;
           uses vrrp-state-attributes;
         }
       }
     } // augment ipv4



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     augment "/if:interfaces/if:interface/ip:ipv6" {
       description "Augment IPv6 interface.";

       container vrrp {
         description
           "Configures the Virtual Router Redundancy Protocol (VRRP)
            version 3 for IPv6.";

         list vrrp-instance {
           must "derived-from-or-self(version, 'vrrp-v3')" {
             description
               "IPv6 is only supported by version 3.";
           }
           key "vrid";
           description
             "Defines a virtual router, identified by a virtual router
              identifier (VRID), within IPv6 address space.";

           uses vrrp-ipv6-attributes;
           uses vrrp-state-attributes;
         } // list vrrp-instance
       } // container vrrp
     } // augment ipv6

     container vrrp {
       config false;
       description "VRRP data at the global level.";

       uses vrrp-global-state-attributes;
     }

     /*
      * Notifications
      */

     notification vrrp-new-master-event {
       description
         "Notification event for a change of VRRP new master.";
       leaf master-ip-address {
         type inet:ip-address;
         mandatory true;
         description
           "IPv4 or IPv6 address of the new master.";
       }
       leaf new-master-reason {
         type new-master-reason-type;
         mandatory true;
         description



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           "Indicates the reason for the virtual router to transition
            to master state.";
       }
     }

     notification vrrp-protocol-error-event {
       description
         "Notification event for a VRRP protocol error.";
       leaf protocol-error-reason {
         type identityref {
           base vrrp:vrrp-error-global;
         }
         mandatory true;
         description
           "Indicates the reason for the protocol error.";
       }
     }

     notification vrrp-virtual-router-error-event {
       description
         "Notification event for an error happened on a virtual
          router.";
       leaf interface {
         type if:interface-ref;
         mandatory true;
         description
           "Indicates the interface for which statistics area
            to be cleared.";
       }

       choice ip-version {
         mandatory true;
         description
           "The error may have happened on either an IPv4 virtual
            router or an IPv6 virtual router. The information
            related to a specific IP version is provided by one of
            the following cases.";
         case ipv4 {
           description "IPv4";
           container ipv4 {
             description
               "Error information for IPv4.";
             leaf vrid {
               type leafref {
                 path "/if:interfaces/if:interface"
                   + "[if:name = current()/../../vrrp:interface]/"
                   + "ip:ipv4/vrrp:vrrp/vrrp:vrrp-instance/vrrp:vrid";
               }



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               mandatory true;
               description
                 "Indicates the virtual router on which the event has
                  occurred.";
             }
           }
         }
         case ipv6 {
           description "IPv6";
           container ipv6 {
             description
               "Error information for IPv6.";
             leaf vrid {
               type leafref {
                 path "/if:interfaces/if:interface"
                   + "[if:name = current()/../../vrrp:interface]/"
                   + "ip:ipv6/vrrp:vrrp/vrrp:vrrp-instance/vrrp:vrid";
               }
               mandatory true;
               description
                 "Indicates the virtual router on which the event has
                  occurred.";
             }
           }
         }
       }

       leaf virtual-router-error-reason {
         type identityref {
           base vrrp:vrrp-error-virtual-router;
         }
         mandatory true;
         description
           "Indicates the reason for the virtual router error.";
       }
     }
   }
   <CODE ENDS>


5.  IANA Considerations

   RFC Ed.: In this section, replace all occurrences of 'XXXX' with the
   actual RFC number (and remove this note).

   This document registers the following namespace URIs in the IETF XML
   registry [RFC3688]:




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

   This document registers the following YANG modules in the YANG Module
   Names registry [RFC7950]:

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

6.  Security Considerations

   The YANG module specified in this document defines a schema for data
   that is designed to be accessed via network management protocols such
   as NETCONF [RFC6241] or RESTCONF [RFC8040].  The lowest NETCONF layer
   is the secure transport layer, and the mandatory-to-implement secure
   transport is Secure Shell (SSH) [RFC6242].  The lowest RESTCONF layer
   is HTTPS, and the mandatory-to-implement secure transport is TLS
   [RFC5246].

   The NETCONF access control model [RFC6536] provides the means to
   restrict access for particular NETCONF or RESTCONF users to a
   preconfigured subset of all available NETCONF or RESTCONF protocol
   operations and content.

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

   /if:interfaces/if:interface/ip:ipv4/vrrp:vrrp/vrrp:vrrp-instance

   /if:interfaces/if:interface/ip:ipv6/vrrp:vrrp/vrrp:vrrp-instance

   Unauthorized access to any data node of these subtrees can adversely
   affect the routing subsystem of both the local device and the
   network.  This may lead to network malfunctions, delivery of packets
   to inappropriate destinations, and other problems.




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

   /ietf-vrrp:vrrp

   /if:interfaces/if:interface/ip:ipv4/vrrp:vrrp/vrrp:vrrp-instance

   /if:interfaces/if:interface/ip:ipv6/vrrp:vrrp/vrrp:vrrp-instance

   Unauthorized access to any data node of these subtrees can disclose
   the operational state information of VRRP on this device.

7.  References

7.1.  Normative References

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

   [RFC2787]  Jewell, B. and D. Chuang, "Definitions of Managed Objects
              for the Virtual Router Redundancy Protocol", RFC 2787,
              DOI 10.17487/RFC2787, March 2000, <https://www.rfc-
              editor.org/info/rfc2787>.

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

   [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>.

   [RFC5798]  Nadas, S., Ed., "Virtual Router Redundancy Protocol (VRRP)
              Version 3 for IPv4 and IPv6", RFC 5798,
              DOI 10.17487/RFC5798, March 2010, <https://www.rfc-
              editor.org/info/rfc5798>.

   [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>.




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   [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>.

   [RFC6527]  Tata, K., "Definitions of Managed Objects for Virtual
              Router Redundancy Protocol Version 3 (VRRPv3)", RFC 6527,
              DOI 10.17487/RFC6527, March 2012, <https://www.rfc-
              editor.org/info/rfc6527>.

   [RFC6536]  Bierman, A. and M. Bjorklund, "Network Configuration
              Protocol (NETCONF) Access Control Model", RFC 6536,
              DOI 10.17487/RFC6536, March 2012, <https://www.rfc-
              editor.org/info/rfc6536>.

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

   [RFC7950]  Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
              RFC 7950, DOI 10.17487/RFC7950, August 2016,
              <https://www.rfc-editor.org/info/rfc7950>.

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

   [I-D.ietf-netmod-rfc7223bis]
              Bjorklund, M., "A YANG Data Model for Interface
              Management", draft-ietf-netmod-rfc7223bis-03 (work in
              progress), January 2018.

   [I-D.ietf-netmod-rfc7277bis]
              Bjorklund, M., "A YANG Data Model for IP Management",
              draft-ietf-netmod-rfc7277bis-03 (work in progress),
              January 2018.

   [I-D.ietf-netmod-revised-datastores]
              Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
              and R. Wilton, "Network Management Datastore
              Architecture", draft-ietf-netmod-revised-datastores-10
              (work in progress), January 2018.





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7.2.  Informative References

   [RFC3768]  Hinden, R., Ed., "Virtual Router Redundancy Protocol
              (VRRP)", RFC 3768, DOI 10.17487/RFC3768, April 2004,
              <https://www.rfc-editor.org/info/rfc3768>.

   [RFC7951]  Lhotka, L., "JSON Encoding of Data Modeled with YANG",
              RFC 7951, DOI 10.17487/RFC7951, August 2016,
              <https://www.rfc-editor.org/info/rfc7951>.

   [I-D.ietf-netconf-subscribed-notifications]
              Voit, E., Clemm, A., Prieto, A., Nilsen-Nygaard, E., and
              A. Tripathy, "Custom Subscription to Event Streams",
              draft-ietf-netconf-subscribed-notifications-09 (work in
              progress), January 2018.

   [I-D.ietf-netconf-yang-push]
              Clemm, A., Voit, E., Prieto, A., Tripathy, A., Nilsen-
              Nygaard, E., Bierman, A., and B. Lengyel, "YANG Datastore
              Subscription", draft-ietf-netconf-yang-push-14 (work in
              progress), February 2018.

   [I-D.ietf-netmod-rfc6087bis]
              Bierman, A., "Guidelines for Authors and Reviewers of YANG
              Data Model Documents", draft-ietf-netmod-rfc6087bis-17
              (work in progress), February 2018.

   [I-D.ietf-netmod-yang-tree-diagrams]
              Bjorklund, M. and L. Berger, "YANG Tree Diagrams", draft-
              ietf-netmod-yang-tree-diagrams-06 (work in progress),
              February 2018.




















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Appendix A.  Data Tree Example

   This section contains an example of an instance data tree in the JSON
   encoding [RFC7951], containing both configuration and state data.

                 Virtual router IP address: fe80::1
              +-----------------+        +-----------------+
              |                 |        |                 |
              |    Router 1     |        |    Router 2     |
              |                 |        |                 |
              +--------+--------+        +--------+--------+
                       |eth1                      |eth1
                       |fe80::11                  |fe80::12
                -------+--------------------------+-------
                       |                          |
                       |fe80::51                  |fe80::52
              +--------+--------+        +--------+--------+
              |     Host 1      |        |     Host 2      |
              | Default gateway:|        | Default gateway:|
              |     fe80::1     |        |     fe80::1     |
              +-----------------+        +-----------------+

   The configuration instance data for Router 1 in the above figure
   could be as follows:



























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   {
     "ietf-interfaces:interfaces": {
       "interface": [
         {
           "name": "eth1",
           "description": "An interface with VRRP enabled.",
           "type": "iana-if-type:ethernetCsmacd",
           "ietf-ip:ipv6": {
             "address": [
               {
                 "ip": "2001:db8:0:1::1",
                 "prefix-length": 64
               },
               {
                 "ip": "fe80::11",
                 "prefix-length": 64
               }
             ],
             "forwarding": true,
             "ietf-vrrp:vrrp": {
               "vrrp-instance": [
                 {
                   "vrid": 1,
                   "version": "vrrp-v3",
                   "priority": 200,
                   "advertise-interval-centi-sec": 50,
                   "virtual-ipv6-addresses": {
                     "virtual-ipv6-address": [
                       "ipv6-address": "fe80::1"
                     ]
                   }
                 }
               ]
             }
           }
         }
       ]
     }
   }

   The cooresponding operational state data for Router 1 could be as
   follows:

   {
     "ietf-interfaces:interfaces": {
       "interface": [
         {
           "name": "eth1",



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           "description": "An interface with VRRP enabled.",
           "type": "iana-if-type:ethernetCsmacd",
           "phys-address": "00:00:5e:00:53:01",
           "oper-status": "up",
           "statistics": {
             "discontinuity-time": "2016-10-24T17:11:27+02:00"
           },
           "ietf-ip:ipv6": {
             "forwarding": true,
             "mtu": 1500,
             "address": [
               {
                 "ip": "2001:db8:0:1::1",
                 "prefix-length": 64,
                 "origin": "static",
                 "status": "preferred"
               },
               {
                 "ip": "fe80::11",
                 "prefix-length": 64,
                 "origin": "static",
                 "status": "preferred"
               }
             ]
             "ietf-vrrp:vrrp": {
               "vrrp-instance": [
                 {
                   "vrid": 1,
                   "version": "vrrp-v3",
                   "log-state-change": false,
                   "preempt": {
                     "enabled": true,
                     "hold-time": 0
                   }
                   "priority": 200,
                   "accept-mode": false,
                   "advertise-interval-centi-sec": 50,
                   "virtual-ipv6-addresses": {
                     "virtual-ipv6-address": [
                       "ipv6-address": "fe80::1"
                     ]
                   },
                   "state": "master",
                   "is-owner": false,
                   "last-adv-source": "fe80::11",
                   "up-datetime": "2016-10-24T17:11:27+02:00",
                   "master-down-interval": 161,
                   "skew-time": 11,



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                   "last-event": "vrrp-event-interface-up",
                   "new-master-reason": "priority",
                   "statistics": {
                     "discontinuity-datetime":
                       "2016-10-24T17:11:27+02:00",
                     "master-transitions": 2,
                     "advertisement-recv": 20,
                     "advertisement-sent": 12,
                     "interval-errors": 0,
                     "priority-zero-pkts-rcvd": 0,
                     "priority-zero-pkts-sent": 0,
                     "invalid-type-pkts-rcvd": 0,
                     "address-list-errors": 0,
                     "packet-length-errors": 1
                   }
                 }
               ]
             }
           }
         }
       ]
     }
   }

   {
     "ietf-vrrp:vrrp": {
       "virtual-routers": 3,
       "interfaces": 2,
       "statistics": {
         "discontinuity-datetime": "2016-10-24T17:11:27+02:00",
         "checksum-errors": 2,
         "version-errors": 0,
         "vrid-errors": 0,
         "ip-ttl-errors": 1
       }
     }
   }

Authors' Addresses

   Xufeng Liu (editor)
   Jabil
   8281 Greensboro Drive, Suite 200
   McLean  VA 22102
   USA

   EMail: Xufeng_Liu@jabil.com




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   Athanasios Kyparlis
   Jabil
   8281 Greensboro Drive, Suite 200
   McLean  VA 22102
   USA

   EMail: Athanasios_Kyparlis@jabil.com


   Ravi Parikh
   VMware
   3425 Hillview Avenue
   Palo Alto  CA 94304
   USA

   EMail: parikhr@vmware.com


   Acee Lindem
   Cisco Systems
   301 Midenhall Way
   Cary  NC 27513
   USA

   EMail: acee@cisco.com


   Mingui Zhang
   Huawei Technologies
   No. 156 Beiqing Rd. Haidian District
   Beijing  100095
   P.R. China

   EMail: zhangmingui@huawei.com

















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