Babel Working Group M. Jethanandani
Internet-Draft VMware
Intended status: Standards Track B. Stark
Expires: January 23, 2020 AT&T
July 22, 2019

YANG Data Model for Babel
draft-ietf-babel-yang-model-02

Abstract

This document defines a data model for the Babel routing protocol. The data model is defined using the YANG data modeling language.

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 BCP 14[RFC8174] when, and only when, they appear in all capitals, as shown here..

Status of This Memo

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

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

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

This Internet-Draft will expire on January 23, 2020.

Copyright Notice

Copyright (c) 2019 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 (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.


Table of Contents

1. Introduction

This document defines a data model for the Babel routing protocol [I-D.ietf-babel-rfc6126bis]. The data model is defined using YANG 1.1 data modeling language and is Network Management Datastore Architecture (NDMA) compatible. It is based on the Babel Information Model.

1.1. Note to RFC Editor

Artwork in this document contains shorthand references to drafts in progress. Please apply the following replacements and remove this note before publication.

1.2. Definitions and Acronyms

1.3. Tree Diagram Annotations

For a reference to the annotations used in tree diagrams included in this draft, please see YANG Tree Diagrams.

2. Babel Module

This document defines a YANG 1.1 data model for the configuration and management of Babel. The YANG module is based on the Babel Information Model.

2.1. Information Model

There are a few things that should be noted between the Babel Information Model and this data module. The information model mandates the definition of some of the attributes, e.g. babel-implementation-version or the babel-self-router-id. These attributes are marked a read-only objects in the information module as well as in this data module. However, there is no way in the data module to mandate that a read-only attribute be present. It is up to the implementation of this data module to make sure that the attributes that are marked read-only and are mandatory are indeed present.

2.2. Tree Diagram

The following diagram illustrates a top level hierarchy of the model. In addition to information like the version number implemented by this device, the model contains subtrees on constants, interfaces, routes and security.


module: ietf-babel
  augment /rt:routing/rt:control-plane-protocols
            /rt:control-plane-protocol:
    +--rw babel!
       +--ro version?                  string
       +--rw enable                    boolean
       +--ro router-id                 binary
       +--ro link-properties*          identityref
       +--ro sequence-number?          uint16
       +--ro metric-comp-algorithms*   identityref
       +--ro security-supported*       identityref
       +--ro hmac-algorithms*          identityref
       +--ro dtls-cert-types*          identityref
       +--rw stats-enable?             boolean
       +--rw constants
       |     ...
       +--rw interfaces* [reference]
       |     ...
       +--rw hmac* [name]
       |     ...
       +--rw dtls* [name]
             ...
  augment /rt:routing/rt:ribs/rt:rib/rt:routes/rt:route:
    +--ro routes* [prefix]
       +--ro prefix               inet:ip-prefix
       +--ro router-id?           binary
       +--ro neighbor?            leafref
       +--ro received-metric?     uint16
       +--ro calculated-metric?   uint16
       +--ro seqno?               uint16
       +--ro next-hop?            inet:ip-address
       +--ro feasible?            boolean
       +--ro selected?            boolean

The interfaces subtree describes attributes such as interface object that is being referenced, the type of link as enumerated by Babel Link Properties, and whether the interface is enabled or not.

The constants subtree describes the UDP port used for sending and receiving Babel messages, and the multicast group used to send and receive announcements on IPv6.

The routes subtree describes objects such as the prefix for which the route is advertised, a reference to the neighboring route, and next-hop address.

Finally, for security two subtree are defined to contain HMAC keys and DTLS certificates. The hmac subtree contains keys used with the HMAC security mechanism. The boolean flag babel-hmac-default-apply indicates whether the set of HMAC keys is automatically applied to new interfaces. The dtls subtree contains certificates used with DTLS security mechanism. Similar to the HMAC mechanism, the boolean flag babel-dtls-default-apply indicates whether the set of DTLS certificates is automatically applied to new interfaces.

2.3. YANG Module

This module augments A YANG Data Model for Interface Management, YANG Routing Management, and imports definitions from Common YANG Data Types.

<CODE BEGINS> file "ietf-babel@2019-07-22.yang"

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

  import ietf-yang-types {
    prefix yt;
    reference
      "RFC 6991 - Common YANG Data Types.";
  }
  import ietf-inet-types {
    prefix inet;
    reference
      "RFC 6991 - Common YANG Data Types.";
  }
  import ietf-interfaces {
    prefix if;
    reference
      "RFC 8343 - A YANG Data Model for Interface Management";
  }
  import ietf-routing {
    prefix "rt";
    reference
      "RFC 8349 - YANG Routing Management";
  }

  organization
    "IETF Babel routing protocol Working Group";

  contact
    "WG Web: http://tools.ietf.org/wg/babel/
     WG List: babel@ietf.org

     Editor: Mahesh Jethanandani
             mjethanandani@gmail.com
     Editor: Barbara Stark
             bs7652@att.com";

  description
    "This YANG module defines a model for the Babel routing
     protocol.

     Copyright (c) 2019 IETF Trust and the persons identified as
     the document authors.  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 RFC itself for full legal notices.";

  revision 2019-07-22 {
    description
      "Initial version.";
    reference
      "RFC XXX: Babel YANG Data Model.";
  }

  /*
   * Identities
   */
  identity link-property {
    description
      "Base identity from which all Babel Link Types are derived.";
  }

  identity other {
    base "link-property";
    description
      "No link property information available.";
  }

  identity tunnel {
    base "link-property";
    description
      "A tunneled interface over unknown physical link.";
  }

  identity wired {
    base "link-property";
    description
      "A wired link with fixed physical properties.";
  }

  identity wireless {
    base "link-property";
    description
      "Wireless link type for Babel Routing Protocol.";
  }

  identity metric-comp-algorithms {
    description
      "Base identity from which all Babel metric comp algorithms
       are derived.";
  }
  identity k-out-of-j {
    base "metric-comp-algorithms";
    description
      "k-out-of-j algorithm.";
  }
  identity etx {
    base "metric-comp-algorithms";
    description
      "Expected Transmission Count.";
  }

  /*
   * Babel security type identities
   */
  identity security-supported {
    description
      "Base identity from which all Babel security types are
       derived.";
  }

  identity hmac {
    base security-supported;
    description
      "HMAC supported.";
  }

  identity dtls {
    base security-supported;
    description
      "Datagram Transport Layer Security (DTLS) supported.";
    reference
      "RFC 6347, Datagram Transport Layer Security Version 1.2.";
  }

  /*
   * Babel HMAC algorithms identities.
   */
  identity hmac-algorithms {
    description
      "Base identity for all Babel HMAC algorithms.";
  }

  identity hmac-sha256 {
    base hmac-algorithms;
    description
      "HMAC-SHA256 algorithm supported.";
  }

  identity blake2s {
    base hmac-algorithms;
    description
      "BLAKE2s algorithm supported.";
    reference
      "RFC 7693, The BLAKE2 Cryptographic Hash and Message 
       Authentication Code (MAC).";
  }

  /*
   * Babel Cert Types
   */
  identity dtls-cert-types {
    description
      "Base identity for Babel DTLS certificate types.";
  }

  identity x-509 {
    base dtls-cert-types;
    description
      "X.509 certificate type.";
  }

  identity raw-public-key {
    base dtls-cert-types;
    description
      "Raw Public Key type.";
  }
  
  /*
   * Babel routing protocol identity.
   */
  identity babel {
    base "rt:routing-protocol";
    description
      "Babel routing protocol";
  }
  
  /*
   * Features
   */

  /*
   * Features supported
   */
  
  /*
   * Typedefs
   */

  /*
   * Groupings
   */
  grouping routes {
    list routes {
      key "prefix";
      config false;

      leaf prefix {
	type inet:ip-prefix;
	description
	  "Prefix (expressed in ip-address/prefix-length format) for
           which this route is advertised.";
	reference
	  "RFC ZZZZ, Babel Information Model, Section 3.6.";
      }

      leaf router-id {
	type binary;
	description
	  "router-id of the source router for which this route is
           advertised.";
	reference
	  "RFC ZZZZ, Babel Information Model, Section 3.6.";
      }

      leaf neighbor {
	type leafref {
	  path "/rt:routing/rt:control-plane-protocols/" +
	       "rt:control-plane-protocol/babel/interfaces/" +
	       "neighbor-objects/neighbor-address";
	}
	description
	  "Reference to the babel-neighbors entry for the neighbor
           that advertised this route.";
	reference
	  "RFC ZZZZ, Babel Information Model, Section 3.6.";
      }

      leaf received-metric {
        type uint16;
        description
          "The metric with which this route was advertised by the
             neighbor, or maximum value (infinity) to indicate a the
             route was recently retracted and is temporarily
             unreachable. this metric will be 0 (zero) if the route
             was not received from a neighbor but was generated
             through other means. Either babel-route-calculated-metric
             or babel-route-received-metric MUST be provided.";
        reference
          "RFC ZZZZ, Babel Information Model, Section 3.6,
             draft-ietf-babel-rfc6126bis, The Babel Routing Protocol,
             Section 3.5.5.";
      }

      leaf calculated-metric {
        type uint16;
        description
          "A calculated metric for this route. How the metric is
             calculated is implementation-specific. Maximum value
             (infinity) indicates the route was recently retracted
             and is temporarily unreachable. Either
             babel-route-calculated-metric or
             babel-route-received-metric MUST be provided.";
        reference
          "RFC ZZZZ, Babel Information Model, Section 3.6,
             draft-ietf-babel-rfc6126bis, The Babel Routing Protocol,
             Section 3.5.5.";
      }

      leaf seqno {
	type uint16;
	description
	  "The sequence number with which this route was advertised.";
	reference
	  "RFC ZZZZ, Babel Information Model, Section 3.6.";
      }

      leaf next-hop {
	type inet:ip-address;
	description
	  "The next-hop address of this route. This will be empty if
           this route has no next-hop address.";
	reference
	  "RFC ZZZZ, Babel Information Model, Section 3.6.";
      }

      leaf feasible {
	type boolean;
	description
	  "A boolean flag indicating whether this route is feasible.";
	reference
	  "RFC ZZZZ, Babel Information Model, Section 3.6,
           draft-ietf-babel-rfc6126bis, The Babel Routing Protocol,
           Section 3.5.1.";
      }

      leaf selected {
	type boolean;
	description
	  "A boolean flag indicating whether this route is selected,
           i.e., whether it is currently being used for forwarding and
           is being advertised.";
	reference
	  "RFC ZZZZ, Babel Information Model, Section 3.6.";
      }
      description
	"A set of babel-route-obj objects. Includes received and
         routes routes.";
      reference
	"RFC ZZZZ, Babel Information Model, Section 3.1.";
    }
    description
      "Common grouping for routing used in RIB augmentation.";
  }

  /*
   * Data model
   */

  augment "/rt:routing/rt:control-plane-protocols/" +
    "rt:control-plane-protocol" {
    when "derived-from-or-self(rt:type, 'babel')" {
      description
	"Augmentation is valid only when the instance of routing type
         is of type 'babel'.";
    }
    description
      "Augment the routing module to support features such as VRF.";
    reference
      "YANG Routing Management, RFC 8349, Lhotka & Lindem, March
       2018.";

    container babel {
      presence "A Babel container.";

      leaf version {
        type string;
        config false;
        description
          "The name and version of this implementation of the Babel 
           protocol.";
        reference
          "RFC ZZZZ, Babel Information Model, Section 3.1.";
      }

      leaf enable {
        type boolean;
	mandatory true;
        description
          "When written, it configures whether the protocol should be
           enabled. A read from the <running> or <intended> datastore
           therefore indicates the configured administrative value of
           whether the protocol is enabled or not.

           A read from the <operational> datastore indicates whether
           the protocol is actually running or not, i.e. it indicates
           the operational state of the protocol.";
	reference
	  "RFC ZZZZ, Babel Information Model, Section 3.1.";
      }

      leaf router-id {
        type binary;
        config false;
        mandatory "true";
        description
          "Every Babel speaker is assigned a router-id, which is an
           arbitrary string of 8 octets that is assumed to be unique
           across the routing domain";
        reference
          "RFC ZZZZ, Babel Information Model, Section 3.1,
           rfc6126bis, The Babel Routing Protocol. Section 3.";
      }

      leaf-list link-properties {
	type identityref {
	  base link-property;
	}
	config false;
	min-elements 1;
	description
	  "Lists the collections of link properties supported by this
           instance of Babel.  Valid enumeration values are defined
           in the Babel Link Properties registry.";
	reference
	  "RFC ZZZZ, Babel Information Model, Section 3.1.";
      }

      leaf sequence-number {
	type uint16;
	config false;
	description
	  "Sequence number included in route updates for routes
         originated by this node.";
	reference
	  "RFC ZZZZ, Babel Information Model, Section 3.1.";
      }

      leaf-list metric-comp-algorithms {
	type identityref {
	  base "metric-comp-algorithms";
	}
	config false;
	min-elements 1;
        description
          "List of cost compute algorithms supported by this
           implementation of Babel.";
        reference
          "RFC ZZZZ, Babel Information Model, Section 3.1.";
      }

      leaf-list security-supported {
	type identityref {
	  base "security-supported";
	}
	config false;
	min-elements 1;
        description
          "Babel security mechanism used by this implementation or
           per interface.";
        reference
          "RFC ZZZZ, Babel Information Model, Section 3.1.";
      }

      leaf-list hmac-algorithms {
	type identityref {
	  base hmac-algorithms;
	}
	config false;
	description
	  "List of supported HMAC computation algorithms. Possible
           values include 'HMAC-SHA256', 'BLAKE2s'.";
	reference
	  "RFC ZZZZ, Babel Information Model, Section 3.1.";
      }	  

      leaf-list dtls-cert-types {
	type identityref {
	  base dtls-cert-types;
	}
	config false;
	description
	  "List of supported DTLS certificate types. Possible values
           include 'X.509' and 'RawPublicKey'.";
	reference
	  "RFC ZZZZ, Babel Information Model, Section 3.1.";
      }

      leaf stats-enable {
	type boolean;
	description
	  "Indicates whether statistics collection is enabled (true)
           or disabled (false) on all interfaces, including
           neighbor-specific statistics (babel-nbr-stats).";
      }
      
      container constants {
        leaf udp-port {
          type inet:port-number;
          default "6696";
          description
            "UDP port for sending and receiving Babel messages. The
             default port is 6696.";
          reference
            "RFC ZZZZ, Babel Information Model, Section 3.2.";
        }

	leaf mcast-group {
	  type inet:ip-address;
	  default "ff02:0:0:0:0:0:1:6";
	  description
	    "Multicast group for sending and receiving multicast
             announcements on IPv6.";
	  reference
	    "RFC ZZZZ, Babel Information Model, Section 3.2.";
	}
	description
	  "Babel Constants object.";
	reference
	  "RFC ZZZZ, Babel Information Model, Section 3.1.";
      }

      list interfaces {
        key "reference";

        leaf reference {
          type if:interface-ref;
          description
            "Reference to an interface object as defined by the data
             model (e.g., YANG, BBF TR-181); data model is assumed to
             allow for referencing of interface objects which may be at
             any layer (physical, Ethernet MAC, IP, tunneled IP, etc.).
             Referencing syntax will be specific to the data model. If
             there is no set of interface objects available, this should
             be a string that indicates the interface name used by the
             underlying operating system.";
          reference
            "RFC ZZZZ, Babel Information Model, Section 3.3.";
        }

	leaf enable {
          type boolean;
          default "true";
          description
	    "If true, babel sends and receives messages on this
             interface. If false, babel messages received on this
             interface are ignored and none are sent.";
          reference
            "RFC ZZZZ, Babel Information Model, Section 3.3.";
	}

	leaf link-properties {
          type identityref {
            base link-property;
          }
	  default "wired";
          description
	    "Indicates the properties of the link. The value MUST be
             one of those listed in the babel-supported-link-
             properties parameter. Valid enumeration values are
             identity-refs derived from properties identified in
             Babel Link Properties registry.";
          reference
            "RFC ZZZZ, Babel Information Model, Section 3.3.";
        }

	leaf metric-algorithm {
	  type identityref {
	    base metric-comp-algorithms;
	  }
	  default "k-out-of-j";
	  description
	    "Indicates the metric computation algorithm used on this 
             interface. The value MUST be one of those listed in the
             babel-information-obj babel-metric-comp-algorithms
             parameter.";
	}

	leaf mcast-hello-seqno {
	  type uint16;
	  config false;
	  description
	    "The current sequence number in use for multicast hellos
           sent on this interface.";
	  reference
	    "RFC ZZZZ, Babel Information Model, Section 3.3.";
	}

        leaf mcast-hello-interval {
          type uint16;
          config false;
          description
            "The current multicast hello interval in use for hellos
             sent on this interface.";
          reference
            "RFC ZZZZ, Babel Information Model, Section 3.3.";
        }

	leaf update-interval {
	  type uint16;
	  units centiseconds;
	  config false;
	  description
	    "The current update interval in use for this interface.
             Units are centiseconds.";
	  reference
	    "RFC ZZZZ, Babel Information Model, Section 3.3.";
	}

        leaf hmac-enable {
          type boolean;
          description
            "Indicates whether the HMAC security mechanism is enabled
           (true) or disabled (false).";
          reference
            "RFC ZZZZ, Babel Information Model, Section 3.3.";
        }

	leaf-list hmac-keys {
	  type leafref {
	    path "../../hmac/name";
	  }
	  description
	    "List of references to the babel-hmac entries that apply
             to this interface. When an interface instance is created,
             all babel-hmac-key-sets instances with 
             babel-hmac-default-apply 'true' will be included in this
             list.";
	  reference
	    "RFC ZZZZ, Babel Information Model, Section 3.3.";
	}

	leaf hmac-algorithm {
	  type identityref {
	    base hmac-algorithms;
	  }
	  description
	    "The name of the HMAC algorithm used on this interface.
             The value is one of the identities listed as part of
             babel-hmac-algorithms at a global level.";
	  reference
	    "RFC ZZZZ, Babel Information Model, Section 3.3.";
	}

	leaf hmac-verify {
	  type boolean;
	  description
	    "A Boolean flag indicating whether HMAC hashes in
             incoming Babel packets are required to be present and
             are verified.  If this parameter is 'true', incoming
             packets are required to have a valid HMAC hash.";
	  reference
	    "RFC ZZZZ, Babel Information Model, Section 3.3.";
	}

        leaf dtls-enable {
          type boolean;
          description
            "Indicates whether the DTLS security mechanism is enabled
           (true) or disabled (false).";
          reference
            "RFC ZZZZ, Babel Information Model, Section 3.3.";
        }

	leaf-list dtls-certs {
	  type leafref {
	    path "../../dtls/name";
	  }
	  description
	    "List of references to the babel-dtls-cert-sets entries
             that apply to this interface.  When an interface instance
             is created, all babel-dtls instances with
             babel-dtls-default-apply 'true' will be included in
             this list.";
	  reference
	    "RFC ZZZZ, Babel Information Model, Section 3.3.";
	}

	leaf dtls-cached-info {
	  type boolean;
	  description
	    "Indicates whether the cached_info extension is included
             in ClientHello and ServerHello packets. The extension
             is included if the value is 'true'.";
	  reference
	    "RFC ZZZZ, Babel Information Model, Section 3.3.";
	}

	leaf-list dtls-cert-prefer {
	  type leafref {
	    path "../../dtls/certs/type";
	  }
	  ordered-by user;
	  description
	    "List of supported certificate types, in order of
             preference. The values MUST be among those listed in the
             babel-dtls-cert-types parameter. This list is used to
             populate the server_certificate_type extension in a
             Client Hello.  Values that are present in at least one
             instance in the babel-dtls-certs object of a referenced
             babel-dtls instance and that have a non-empty
             babel-cert-private-key will be used to populate the
             client_certificate_type extension in a Client Hello.";
	  reference
	    "RFC ZZZZ, Babel Information Model, Section 3.3.";
	}

        leaf packet-log-enable {
          type boolean;
          description
            "If true, logging of babel packets received on this
             interface is enabled; if false, babel packets are not
             logged.";
          reference
            "RFC ZZZZ, Babel Information Model, Section 3.3.";
	}

        leaf packet-log {
	  type inet:uri;
	  config false;
          description
	    "A reference or url link to a file that contains a
             timestamped log of packets received and sent on
             babel-udp-port on this interface. The [libpcap] file
             format with .pcap file extension SHOULD be supported for
             packet log files. Logging is enabled / disabled by
             packet-log-enable.";
          reference
            "RFC ZZZZ, Babel Information Model, Section 3.3.";
        }

	container stats {
	  config false;
	  leaf sent-mcast-hello {
	    type yt:counter32;
	    description
	      "A count of the number of multicast Hello packets sent
               on this interface.";
	    reference
	      "RFC ZZZZ, Babel Information Model, Section 3.4.";
	  }

	  leaf sent-mcast-update {
	    type yt:counter32;
	    description
	      "A count of the number of multicast update packets sent
               on this interface.";
	    reference
	      "RFC ZZZZ, Babel Information Model, Section 3.4.";
	  }

	  leaf received-packets {
	    type yt:counter32;
	    description
	      "A count of the number of Babel packets received on
               this interface.";
	    reference
	      "RFC ZZZZ, Babel Information Model, Section 3.4.";
	  }
	  action reset {
	    input {
	      leaf reset-at {
		type yt:date-and-time;
		description
		  "The time when the reset was issued.";
	      }
	    }
	    output {
	      leaf reset-finished-at {
		type yt:date-and-time;
		description
		  "The time when the reset finished.";
	      }
	    }
	  }
	  description
	    "Statistics collection object for this interface.";
          reference
            "RFC ZZZZ, Babel Information Model, Section 3.3.";
	}

	list neighbor-objects {
	  key "neighbor-address";
	  config false;

	  leaf neighbor-address {
	    type inet:ip-address;
	    description
	      "IPv4 or v6 address the neighbor sends packets from.";
	    reference
	      "RFC ZZZZ, Babel Information Model, Section 3.5.";
	  }

          leaf hello-mcast-history {
            type string;
            description
              "The multicast Hello history of whether or not the
               multicast Hello packets prior to babel-exp-mcast-
               hello-seqno were received, with a '1' for the most
               recent Hello placed in the most significant bit and
               prior Hellos shifted right (with '0' bits placed
               between prior Hellos and most recent Hello for any
               not-received Hellos); represented as a string using
               utf-8 encoded hex digits where a '1' bit = Hello
               received and a '0' bit = Hello not received.";
            reference
              "RFC ZZZZ, Babel Information Model, Section 3.5.";
          }

          leaf hello-ucast-history {
            type string;
            description
              "The unicast Hello history of whether or not the
               unicast Hello packets prior to babel-exp-ucast-
               hello-seqno were received, with a '1' for the most
               recent Hello placed in the most significant bit and
               prior Hellos shifted right (with '0' bits placed
               between prior Hellos and most recent Hello for any
               not-received Hellos); represented as a string using
               utf-8 encoded hex digits where a '1' bit = Hello
               received and a '0' bit = Hello not received.";
            reference
              "RFC ZZZZ, Babel Information Model, Section 3.5.";
          }

          leaf txcost {
            type int32;
	    default "0";
            description
              "Transmission cost value from the last IHU packet
               received from this neighbor, or maximum value
               (infinity) to indicates the IHU hold timer for this
               neighbor has expired description.";
            reference
              "RFC ZZZZ, Babel Information Model, Section 3.5.";
          }

          leaf exp-mcast-hello-seqno {
            type uint16;
	    default "0";
            description
              "Expected multicast Hello sequence number of next Hello
               to be received from this neighbor; if multicast Hello
               packets are not expected, or processing of multicast
               packets is not enabled, this MUST be 0.";
            reference
              "RFC ZZZZ, Babel Information Model, Section 3.5.";
          }

          leaf exp-ucast-hello-seqno {
            type uint16;
	    default "0";
            description
              "Expected unicast Hello sequence number of next Hello to
               be received from this neighbor; if unicast Hello
               packets are not expected, or processing of unicast
               packets is not enabled, this MUST be 0.";
            reference
              "RFC ZZZZ, Babel Information Model, Section 3.5.";
          }

	  leaf ucast-hello-seqno {
	    type uint16;
	    description
	      "Expected unicast Hello sequence number of next Hello
               to be received from this neighbor. If unicast Hello
               packets are not expected, or processing of unicast
               packets is not enabled, this MUST be 0.";
            reference
              "RFC ZZZZ, Babel Information Model, Section 3.5.";
	  }

	  leaf ucast-hello-interval {
	    type uint16;
	    units centiseconds;
	    description
	      "The current interval in use for unicast hellos sent to
               this neighbor. Units are centiseconds.";
            reference
              "RFC ZZZZ, Babel Information Model, Section 3.5.";
	  }
	  
          leaf rxcost {
            type int32;
            description
              "Reception cost calculated for this neighbor. This value
               is usually derived from the Hello history, which may be
               combined with other data, such as statistics maintained
               by the link layer. The rxcost is sent to a neighbor in
               each IHU.";
            reference
              "RFC ZZZZ, Babel Information Model, Section 3.5.";
          }

          leaf cost {
            type int32;
            description
              "Link cost is computed from the values maintained in
               the neighbor table. The statistics kept in the neighbor
               table about the reception of Hellos, and the txcost
               computed from received IHU packets.";
            reference
              "RFC ZZZZ, Babel Information Model, Section 3.5.";
          }

	  container stats {
	    config false;
	    leaf sent-ucast-hello {
	      type yt:counter32;
	      description
		"A count of the number of unicast Hello packets sent 
                 to this neighbor.";
              reference
		"RFC ZZZZ, Babel Information Model, Section 3.6.";
	    }

	    leaf sent-ucast-update {
	      type yt:counter32;
	      description
		"A count of the number of unicast update packets sent
                 to this neighbor.";
              reference
		"RFC ZZZZ, Babel Information Model, Section 3.6.";
	    }

	    leaf sent-ihu {
	      type yt:counter32;
	      description
		"A count of the number of IHU packets sent to this
                 neighbor.";
              reference
		"RFC ZZZZ, Babel Information Model, Section 3.6.";
	    }

	    leaf received-hello {
	      type yt:counter32;
	      description
		"A count of the number of Hello packets received from
                 this neighbor.";
              reference
		"RFC ZZZZ, Babel Information Model, Section 3.6.";
	    }

	    leaf received-update {
	      type yt:counter32;
	      description
		"A count of the number of update packets received 
                 from this neighbor.";
              reference
		"RFC ZZZZ, Babel Information Model, Section 3.6.";
	    }

	    leaf received-ihu {
	      type yt:counter32;
	      description
		"A count of the number of IHU packets received from 
                 this neighbor.";
              reference
		"RFC ZZZZ, Babel Information Model, Section 3.6.";
	    }

	    action reset {
	      input {
		leaf reset-at {
		  type yt:date-and-time;
		  description
		    "The time the reset was issued.";
		}
	      }
	      output {
		leaf reset-finished-at {
		  type yt:date-and-time;
		  description
		    "The time when the reset operation finished.";
		}
	      }
	    }
	    description
	      "Statistics collection object for this neighbor.";
	    reference
	      "RFC ZZZZ, Babel Information Model, Section 3.6.";
	  }
          description
            "A set of Babel Neighbor Object.";
          reference
            "RFC ZZZZ, Babel Information Model, Section 3.5.";
        }
        description
          "A set of Babel Interface objects.";
        reference
          "RFC ZZZZ, Babel Information Model, Section 3.3.";
      }

      list hmac {
	key "name";

	leaf name {
	  type string;
	  description
	    "A string that uniquely identifies the hmac object.";
	}

	leaf default-apply {
	  type boolean;
	  description
	    "A Boolean flag indicating whether this babel-hmac
             instance is applied to all new interfaces, by default. If
             'true', this instance is applied to new
             babel-interfaces instances at the time they are created,
             by including it in the babel-interface-hmac-keys list.
             If 'false', this instance is not applied to new
             babel-interfaces instances when they are created.";
	  reference
	    "RFC ZZZZ, Babel Information Model, Section 3.8.";
	}

	list keys {
	  key "name";
	  min-elements "1";
	  
	  leaf name {
	    type string;
	    mandatory "true";
	    description
	      "A unique name for this HMAC key that can be used to
               identify the key in this object instance, since the key
               value is not allowed to be read. This value can only be
               provided when this instance is created, and is not
               subsequently writable.";
	    reference
	      "RFC ZZZZ, Babel Information Model, Section 3.9.";
	  }

	  leaf use-sign {
	    type boolean;
	    mandatory "true";
	    description
	      "Indicates whether this key value is used to sign sent 
               Babel packets. Sent packets are signed using this key
               if the value is 'true'. If the value is 'false', this
               key is not used to sign sent Babel packets.";
	    reference
	      "RFC ZZZZ, Babel Information Model, Section 3.9.";
	  }

	  leaf use-verify {
	    type boolean;
	    mandatory "true";
	    description
	      "Indicates whether this key value is used to verify
               incoming Babel packets. This key is used to verify
               incoming packets if the value is 'true'. If the value
               is 'false', no HMAC is computed from this key for
               comparing an incoming packet.";
	    reference
	      "RFC ZZZZ, Babel Information Model, Section 3.9.";
	  }

	  leaf value {
	    type binary;
	    mandatory "true";
	    description
	      "The value of the HMAC key. An implementation MUST NOT
               allow this parameter to be read. This can be done by
               always providing an empty string, or through
               permissions, or other means. This value MUST be
               provided when this instance is created, and is not
               subsequently writable.";
	    reference
	      "RFC ZZZZ, Babel Information Model, Section 3.9.";
	  }

	  action test {
	    input {
	      leaf test-string {
		type binary;
		mandatory "true";
		description
		  "The test string on which this test has to be
                   performed.";
	      }
	    }
	    output {
	      leaf resulting-hash {
		type binary;
		mandatory "true";
		description
                  "An operation that allows the HMAC key and hash
                   algorithm to be tested to see if they produce an
                   expected outcome. Input to this operation is a
                   binary string. The implementation is expected to
                   create a hash of this string using the
                   babel-hmac-key-value and the babel-hmac-algorithm.
                   The output of this operation is the resulting hash,
                   as a binary string.";
		reference
		  "RFC ZZZZ, Babel Information Model, Section 3.9.";
	      }
	    }
	  }
	  description
	    "A set of babel-hmac-keys-obj objects.";
	  reference
	    "RFC ZZZZ, Babel Information Model, Section 3.8.";
	}
	description
	  "A babel-hmac-obj object. If this object is implemented, it 
           provides access to parameters related to the HMAC security
           mechanism.";
        reference
          "RFC ZZZZ, Babel Information Model, Section 3.1.";
      }

      list dtls {
	key "name";

	leaf name {
	  type string;
	  description
	    "TODO: This attribute does not exist in the model, but is 
             needed for this model to work.";
	}

	leaf default-apply {
	  type boolean;
	  mandatory "true";
	  description
	    "A Boolean flag indicating whether this babel-dtls
             instance is applied to all new interfaces, by default. If
             'true', this instance is applied to new babel-interfaces
             instances at the time they are created, by including it
             in the babel-interface-dtls-certs list. If 'false',
             this instance is not applied to new babel-interfaces
             instances when they are created.";
          reference
            "RFC ZZZZ, Babel Information Model, Section 3.10.";
	}

	list certs {
	  key "name";
	  min-elements "1";
	    
	  leaf name {
	    type string;
	    description
	      "A unique name that identifies the cert in the list.";
	  }

	  leaf value {
	    type string;
	    mandatory "true";
	    description
	      "The DTLS certificate in PEM format [RFC7468]. This
               value can only be provided when this instance is
               created, and is not subsequently writable.";
	    reference
	      "RFC ZZZZ, Babel Information Model, Section 3.11.";
	  }

	  leaf type {
	    type identityref {
	      base dtls-cert-types;
	    }
	    mandatory "true";
	    description
	      "The name of the certificate type of this object
               instance. The value MUST be the same as one of the
               enumerations listed in the babel-dtls-cert-types
               parameter. This value can only be provided when this
               instance is created, and is not subsequently writable.";
	    reference
	      "RFC ZZZZ, Babel Information Model, Section 3.11.";
	  }

	  leaf private-key {
	    type binary;
	    mandatory "true";
	    description
	      "The value of the private key. If this is non-empty,
               this certificate can be used by this implementation to
               provide a certificate during DTLS handshaking. An
               implementation MUST NOT allow this parameter to be
               read. This can be done by always providing an empty
               string, or through permissions, or other means. This
               value can only be provided when this instance is
               created, and is not subsequently writable.";
	    reference
	      "RFC ZZZZ, Babel Information Model, Section 3.11.";
	  }

	  action test {
	    input {
	      leaf test-string {
		type binary;
		mandatory "true";
		description
		  "The test string on which this test has to be
                   performed.";
	      }
	    }
	    output {
	      leaf resulting-hash {
		type binary;
		mandatory "true";
		description
		  "The output of this operation is a binary string,
                   and is the resulting hash computed using the
                   certificate public key, and the SHA-256
                   hash algorithm.";
	      }
	    }
	  }
	  description
	    "A set of babel-dtls-keys-obj objects. This contains 
             both certificates for this implementation to present
             for authentication, and to accept from others.
             Certificates with a non-empty babel-cert-private-key
             can be presented by this implementation for
             authentication.";
	  reference
	    "RFC ZZZZ, Babel Information Model, Section 3.10.";
	}
	description
	  "A babel-dtls-obj object. If this object is implemented,
           it provides access to parameters related to the DTLS
           security mechanism.";
	reference
	  "RFC ZZZZ, Babel Information Model, Section 3.1";
      }
      description
        "Babel Information Objects.";
      reference
        "RFC ZZZZ, Babel Information Model, Section 3.";
    }
  }
  augment "/rt:routing/rt:ribs/rt:rib/rt:routes/rt:route" {
    when "derived-from(rt:source-protocol, 'babel')" {
      description
	"Augmentation is valid for a routes whose source protocol
         is Babel.";
    }
    description
      "Babel specific route attributes.";
    uses routes;
  }
}

<CODE ENDS>

2.4. Example

<?xml version="1.0" encoding="UTF-8"?>
<config xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
  <routing
      xmlns="urn:ietf:params:xml:ns:yang:ietf-routing">
    <control-plane-protocols>
      <control-plane-protocol>
	<type
	    xmlns:babel="urn:ietf:params:xml:ns:yang:ietf-babel">babel:babel
	</type>
	<name>name:babel</name>
	<babel
	    xmlns="urn:ietf:params:xml:ns:yang:ietf-babel">
	  <enable>true</enable>
	  <stats-enable>true</stats-enable>
	</babel>
      </control-plane-protocol>
    </control-plane-protocols>
  </routing>
</config>

The following snippet demonstrates how this data module can be configured. In this example, the routing protocol being configured is Babel, and statistics gathering is enabled.

3. IANA Considerations

This document registers one URIs and one YANG module.

3.1. URI Registrations

URI: urn:ietf:params:xml:ns:yang:ietf-babel

3.2. YANG Module Name Registration

This document registers one YANG module in the YANG Module Names registry YANG.

Name:ietf-babel
Namespace: urn:ietf:params:xml:ns:yang:ietf-babel
prefix: babel
reference: RFC XXXX 

4. Security Considerations

The YANG module specified in this document defines a schema for data that is designed to be accessed via network management protocol such as NETCONF or RESTCONF. The lowest NETCONF layer is the secure transport layer and the mandatory-to-implement secure transport is SSH. The lowest RESTCONF layer is HTTPS, and the mandatory-to-implement secure transport is TLS.

The NETCONF Access Control Model (NACM) provides the means to restrict access for particular NETCONF users to a pre-configured subset of all available NETCONF protocol operations and content.

There are a number of data nodes defined in the YANG module which are writable/created/deleted (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:

5. Acknowledgements

6. References

6.1. Normative References

[I-D.ietf-babel-rfc6126bis] Chroboczek, J. and D. Schinazi, "The Babel Routing Protocol", Internet-Draft draft-ietf-babel-rfc6126bis-11, June 2019.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997.
[RFC6991] Schoenwaelder, J., "Common YANG Data Types", RFC 6991, DOI 10.17487/RFC6991, July 2013.
[RFC7950] Bjorklund, M., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017.
[RFC8343] Bjorklund, M., "A YANG Data Model for Interface Management", RFC 8343, DOI 10.17487/RFC8343, March 2018.
[RFC8349] Lhotka, L., Lindem, A. and Y. Qu, "A YANG Data Model for Routing Management (NMDA Version)", RFC 8349, DOI 10.17487/RFC8349, March 2018.

6.2. Informative References

[I-D.ietf-babel-information-model] Stark, B. and M. Jethanandani, "Babel Information Model", Internet-Draft draft-ietf-babel-information-model-07, July 2019.
[RFC6020] Bjorklund, M., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010.
[RFC6241] Enns, R., Bjorklund, M., Schoenwaelder, J. and A. Bierman, "Network Configuration Protocol (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011.
[RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011.
[RFC8040] Bierman, A., Bjorklund, M. and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017.
[RFC8340] Bjorklund, M. and L. Berger, "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018.
[RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, March 2018.
[RFC8342] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K. and R. Wilton, "Network Management Datastore Architecture (NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018.

Appendix A. An Appendix

Authors' Addresses

Mahesh Jethanandani VMware California USA EMail: mjethanandani@gmail.com
Barbara Stark AT&T Atlanta, GA USA EMail: barbara.stark@att.com