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+Internet Engineering Task Force (IETF)                   M. Jethanandani
+Request for Comments: 9647                                Kloud Services
+Category: Standards Track                                       B. Stark
+ISSN: 2070-1721                                                     AT&T
+                                                            October 2024
+
+
+                      A YANG Data Model for Babel
+
+Abstract
+
+   This document defines a data model for the Babel routing protocol.
+   The data model is defined using the YANG data modeling language.
+
+Status of This Memo
+
+   This is an Internet Standards Track document.
+
+   This document is a product of the Internet Engineering Task Force
+   (IETF).  It represents the consensus of the IETF community.  It has
+   received public review and has been approved for publication by the
+   Internet Engineering Steering Group (IESG).  Further information on
+   Internet Standards is available in Section 2 of RFC 7841.
+
+   Information about the current status of this document, any errata,
+   and how to provide feedback on it may be obtained at
+   https://www.rfc-editor.org/info/rfc9647.
+
+Copyright Notice
+
+   Copyright (c) 2024 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 Revised BSD License text as described in Section 4.e of the
+   Trust Legal Provisions and are provided without warranty as described
+   in the Revised BSD License.
+
+Table of Contents
+
+   1.  Introduction
+     1.1.  Requirements Language
+     1.2.  Tree Diagram Annotations
+   2.  Babel Module
+     2.1.  Information Model
+     2.2.  Tree Diagram
+     2.3.  YANG Module
+   3.  IANA Considerations
+     3.1.  URI Registration
+     3.2.  YANG Module Name Registration
+   4.  Security Considerations
+   5.  References
+     5.1.  Normative References
+     5.2.  Informative References
+   Appendix A.  Tree Diagram and Example Configurations
+     A.1.  Complete Tree Diagram
+     A.2.  Statistics Gathering Enabled
+     A.3.  Automatic Detection of Properties
+     A.4.  Override Default Properties
+     A.5.  Configuring Other Properties
+   Acknowledgements
+   Authors' Addresses
+
+1.  Introduction
+
+   This document defines a data model for the Babel routing protocol
+   [RFC8966].  The data model is defined using YANG 1.1 [RFC7950] and is
+   compatible with Network Management Datastore Architecture (NMDA)
+   [RFC8342].  It is based on the Babel information model [RFC9046].
+   The data model only includes data nodes that are useful for managing
+   Babel over IPv6.
+
+1.1.  Requirements Language
+
+   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
+   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
+   "OPTIONAL" in this document are to be interpreted as described in
+   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
+   capitals, as shown here.
+
+1.2.  Tree Diagram Annotations
+
+   For a reference to the annotations used in tree diagrams included in
+   this document, please see "YANG Tree Diagrams" [RFC8340].
+
+2.  Babel Module
+
+   This document defines a YANG 1.1 [RFC7950] data model for the
+   configuration and management of Babel.  The YANG module is based on
+   the Babel information model [RFC9046].
+
+2.1.  Information Model
+
+   It's worth noting a few differences 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
+   as 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 the version implemented by this device, the model
+   contains subtrees on "constants", "interfaces", "mac-key-set",
+   "dtls", and "routes".
+
+   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 seqno?                uint16
+          +--rw statistics-enabled?   boolean
+          +--rw constants
+          |     ...
+          +--rw interfaces* [reference]
+          |     ...
+          +--rw mac-key-set* [name]
+          |     ...
+          +--rw dtls* [name]
+          |     ...
+          +--ro routes* [prefix]
+                ...
+
+   The "interfaces" subtree describes attributes such as the "interface"
+   object that is being referenced; the type of link, e.g., wired,
+   wireless, or tunnel, as enumerated by "metric-algorithm" and "split-
+   horizon"; 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
+   the "next-hop" address.
+
+   Finally, for security, two subtrees are defined to contain Message
+   Authentication Code (MAC) keys and DTLS certificates.  The "mac-key-
+   set" subtree contains keys used with the MAC security mechanism.  The
+   boolean flag "default-apply" indicates whether the set of MAC keys is
+   automatically applied to new interfaces.  The "dtls" subtree contains
+   certificates used with the DTLS security mechanism.  Similar to the
+   MAC mechanism, the boolean flag "default-apply" indicates whether the
+   set of DTLS certificates is automatically applied to new interfaces.
+
+2.3.  YANG Module
+
+   This YANG module augments the YANG routing management module
+   [RFC8349] to provide a common framework for all routing subsystems.
+   By augmenting the module, it provides a common building block for
+   routes and Routing Information Bases (RIBs).  It also has a reference
+   to an interface defined by "A YANG Data Model for Interface
+   Management" [RFC8343].
+
+   A router running the Babel routing protocol can sometimes determine
+   the parameters it needs to use for an interface based on the
+   interface name.  For example, it can detect that eth0 is a wired
+   interface and that wlan0 is a wireless interface.  This is not true
+   for a tunnel interface, where the link parameters need to be
+   configured explicitly.
+
+   For a wired interface, it will assume "two-out-of-three" is set for
+   "metric-algorithm" and "split-horizon" is set to true.  On the other
+   hand, for a wireless interface, it will assume "etx" is set for
+   "metric-algorithm" and "split-horizon" is set to false.  However, if
+   the wired link is connected to a wireless radio, the values can be
+   overridden by setting "metric-algorithm" to "etx" and "split-horizon"
+   to false.  Similarly, an interface that is a metered 3G link and is
+   used for fallback connectivity needs much higher default time
+   constants, e.g., "mcast-hello-interval" and "update-interval", in
+   order to avoid carrying control traffic as much as possible.
+
+   In addition to the modules used above, this module imports
+   definitions from "Common YANG Data Types" [RFC6991] and references
+   "HMAC: Keyed-Hashing for Message Authentication" [RFC2104], "Using
+   HMAC-SHA-256, HMAC-SHA-384, and HMAC-SHA-512 with IPsec" [RFC4868],
+   "Textual Encodings of PKIX, PKCS, and CMS Structures" [RFC7468], "The
+   BLAKE2 Cryptographic Hash and Message Authentication Code (MAC)"
+   [RFC7693], "Network Configuration Access Control Model" [RFC8341],
+   "The Babel Routing Protocol" [RFC8966], "MAC Authentication for the
+   Babel Routing Protocol" [RFC8967], "Babel Information Model"
+   [RFC9046], "The Datagram Transport Layer Security (DTLS) Protocol
+   Version 1.3" [RFC9147], and "YANG Data Types and Groupings for
+   Cryptography" [RFC9640].
+
+   <CODE BEGINS> file "ietf-babel@2024-10-10.yang"
+   module ietf-babel {
+     yang-version 1.1;
+     namespace "urn:ietf:params:xml:ns:yang:ietf-babel";
+     prefix babel;
+
+     import ietf-yang-types {
+       prefix yang;
+       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: A YANG Data Model for Routing Management (NMDA
+          Version)";
+     }
+     import ietf-crypto-types {
+       prefix ct;
+       reference
+         "RFC 9640: YANG Data Types and Groupings
+          for Cryptography";
+     }
+     import ietf-netconf-acm {
+       prefix nacm;
+       reference
+         "RFC 8341: Network Configuration Access Control Model";
+     }
+
+     organization
+       "IETF Babel routing protocol Working Group";
+
+     contact
+       "WG Web:  https://datatracker.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.
+
+        The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL
+        NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'NOT RECOMMENDED',
+        'MAY', and 'OPTIONAL' in this document are to be interpreted as
+        described in BCP 14 (RFC 2119) (RFC 8174) when, and only when,
+        they appear in all capitals, as shown here.
+
+        Copyright (c) 2024 IETF Trust and the persons identified as
+        authors of the code.  All rights reserved.
+
+        Redistribution and use in source and binary forms, with or
+        without modification, is permitted pursuant to, and subject to
+        the license terms contained in, the Revised BSD License set
+        forth in Section 4.c of the IETF Trust's Legal Provisions
+        Relating to IETF Documents
+        (https://trustee.ietf.org/license-info).
+
+        This version of this YANG module is part of RFC 9647
+        (https://www.rfc-editor.org/info/rfc9647); see the RFC itself
+        for full legal notices.";
+
+     revision 2024-10-10 {
+       description
+         "Initial version.";
+       reference
+         "RFC 9647: A YANG Data Model for Babel";
+     }
+
+     /*
+      * Features
+      */
+
+     feature two-out-of-three-supported {
+       description
+         "This implementation supports the '2-out-of-3'
+          computation algorithm.";
+     }
+
+     feature etx-supported {
+       description
+         "This implementation supports the Expected Transmission Count
+          (ETX) metric computation algorithm.";
+     }
+
+     feature mac-supported {
+       description
+         "This implementation supports MAC-based security.";
+       reference
+         "RFC 8967: MAC Authentication for the Babel Routing
+          Protocol";
+     }
+
+     feature dtls-supported {
+       description
+         "This implementation supports DTLS-based security.";
+       reference
+         "RFC 8968: Babel Routing Protocol over Datagram
+          Transport Layer Security";
+     }
+
+     feature hmac-sha256-supported {
+       description
+         "This implementation supports the HMAC-SHA256 MAC algorithm.";
+       reference
+         "RFC 8967: MAC Authentication for the Babel Routing
+          Protocol";
+     }
+
+     feature blake2s-supported {
+       description
+         "This implementation supports BLAKE2s MAC algorithms.";
+       reference
+         "RFC 8967: MAC Authentication for the Babel Routing
+          Protocol";
+     }
+
+     feature x-509-supported {
+       description
+         "This implementation supports the X.509 certificate type.";
+       reference
+         "RFC 8968: Babel Routing Protocol over Datagram
+          Transport Layer Security";
+     }
+
+     feature raw-public-key-supported {
+       description
+         "This implementation supports the raw public key certificate
+          type.";
+       reference
+         "RFC 8968: Babel Routing Protocol over Datagram
+          Transport Layer Security";
+     }
+
+     /*
+      * Identities
+      */
+
+     identity metric-comp-algorithms {
+       description
+         "Base identity from which all Babel metric computation
+          algorithms MUST be derived.";
+     }
+
+     identity two-out-of-three {
+       if-feature "two-out-of-three-supported";
+       base metric-comp-algorithms;
+       description
+         "2-out-of-3 algorithm.";
+       reference
+         "RFC 8966: The Babel Routing Protocol, Section A.2.1";
+     }
+
+     identity etx {
+       if-feature "etx-supported";
+       base metric-comp-algorithms;
+       description
+         "Expected Transmission Count (ETX) metric computation
+          algorithm.";
+       reference
+         "RFC 8966: The Babel Routing Protocol, Section A.2.2";
+     }
+
+     /*
+      * Babel MAC algorithms identities.
+      */
+
+     identity mac-algorithms {
+       description
+         "Base identity for all Babel MAC algorithms.";
+     }
+
+     identity hmac-sha256 {
+       if-feature "mac-supported";
+       if-feature "hmac-sha256-supported";
+       base mac-algorithms;
+       description
+         "HMAC-SHA256 algorithm supported.";
+       reference
+         "RFC 4868: Using HMAC-SHA-256, HMAC-SHA-384, and HMAC-SHA-512
+          with IPsec";
+     }
+
+     identity blake2s {
+       if-feature "mac-supported";
+       if-feature "blake2s-supported";
+       base mac-algorithms;
+       description
+         "BLAKE2s algorithms supported. Specifically, BLAKE2-128 is
+          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 {
+       if-feature "dtls-supported";
+       if-feature "x-509-supported";
+       base dtls-cert-types;
+       description
+         "X.509 certificate type.";
+     }
+
+     identity raw-public-key {
+       if-feature "dtls-supported";
+       if-feature "raw-public-key-supported";
+       base dtls-cert-types;
+       description
+         "Raw public key certificate type.";
+     }
+
+     /*
+      * Babel routing protocol identity.
+      */
+
+     identity babel {
+       base rt:routing-protocol;
+       description
+         "Babel routing protocol";
+     }
+
+     /*
+      * 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 9046: Babel Information Model, Section 3.6";
+         }
+
+         leaf router-id {
+           type binary {
+             length "8";
+           }
+           description
+             "router-id of the source router for which this route is
+              advertised.";
+           reference
+             "RFC 9046: 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 neighbor-objects entry for the neighbor
+              that advertised this route.";
+           reference
+             "RFC 9046: Babel Information Model, Section 3.6";
+         }
+
+         leaf received-metric {
+           type union {
+             type enumeration {
+               enum null {
+                 description
+                   "Route was not received from a neighbor.";
+               }
+             }
+             type uint16;
+           }
+           description
+             "The metric with which this route was advertised by the
+              neighbor, or maximum value (infinity) to indicate the
+              route was recently retracted and is temporarily
+              unreachable. This metric will be NULL if the
+              route was not received from a neighbor but instead was
+              injected through means external to the Babel routing
+              protocol. At least one of calculated-metric or
+              received-metric MUST be non-NULL.";
+           reference
+             "RFC 9046: Babel Information Model, Section 3.6
+              RFC 8966: The Babel Routing Protocol, Section 2.1";
+         }
+
+         leaf calculated-metric {
+           type union {
+             type enumeration {
+               enum null {
+                 description
+                   "Route has not been calculated.";
+               }
+             }
+             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. At least one of
+              calculated-metric or received-metric MUST be non-NULL.";
+           reference
+             "RFC 9046: Babel Information Model, Section 3.6
+              RFC 8966: The Babel Routing Protocol, Section 2.1";
+         }
+
+         leaf seqno {
+           type uint16;
+           description
+             "The sequence number with which this route was
+              advertised.";
+           reference
+             "RFC 9046: Babel Information Model, Section 3.6";
+         }
+
+         leaf next-hop {
+           type union {
+             type enumeration {
+               enum null {
+                 description
+                   "Route has no next-hop address.";
+               }
+             }
+             type inet:ip-address;
+           }
+           description
+             "The next-hop address of this route. This will be NULL
+              if this route has no next-hop address.";
+           reference
+             "RFC 9046: Babel Information Model, Section 3.6";
+         }
+
+         leaf feasible {
+           type boolean;
+           description
+             "A boolean flag indicating whether this route is
+              feasible.";
+           reference
+             "RFC 9046: Babel Information Model, Section 3.6
+              RFC 8966, 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 9046: Babel Information Model, Section 3.6";
+         }
+         description
+           "A set of babel-route-obj objects. Contains routes known to
+            this node.";
+         reference
+           "RFC 9046: Babel Information Model, Section 3.6";
+       }
+       description
+         "Common grouping for routing used in RIB.";
+     }
+
+     /*
+      * 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 the routing
+            type is of type 'babel'.";
+       }
+       description
+         "Augments the routing module to support a common structure
+          between routing protocols.";
+       reference
+         "RFC 8349: A YANG Data Model for Routing Management (NMDA
+          Version)";
+
+       container babel {
+         presence "A Babel container.";
+         description
+           "Babel information objects.";
+         reference
+           "RFC 9046: Babel Information Model, Section 3";
+
+         leaf version {
+           type string;
+           config false;
+           description
+             "The name and version of this implementation of the Babel
+              protocol.";
+           reference
+             "RFC 9046: 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 9046: Babel Information Model, Section 3.1";
+         }
+
+         leaf router-id {
+           type binary;
+           must '../enable = "true"';
+           config false;
+           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.
+
+              The router-id is valid only if the protocol is enabled,
+              at which time a non-zero value is assigned.";
+           reference
+             "RFC 9046: Babel Information Model, Section 3.1
+              RFC 8966: The Babel Routing Protocol, Section 3";
+         }
+
+         leaf seqno {
+           type uint16;
+           config false;
+           description
+             "Sequence number included in route updates for routes
+              originated by this node.";
+           reference
+             "RFC 9046: Babel Information Model, Section 3.1";
+         }
+
+         leaf statistics-enabled {
+           type boolean;
+           description
+             "Indicates whether statistics collection is enabled
+              ('true') or disabled ('false') on all interfaces.
+              On transition to enabled, existing statistics
+              values are not cleared and will be incremented as
+              new packets are counted.";
+         }
+
+         container constants {
+           description
+             "Babel constants object.";
+           reference
+             "RFC 9046: Babel Information Model, Section 3.1";
+
+           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 9046: Babel Information Model, Section 3.2";
+           }
+
+           leaf mcast-group {
+             type inet:ip-address;
+             default "ff02::1:6";
+             description
+               "Multicast group for sending and receiving multicast
+                announcements on IPv6.";
+             reference
+               "RFC 9046: Babel Information Model, Section 3.2";
+           }
+         }
+
+         list interfaces {
+           key "reference";
+
+           description
+             "A set of Babel interface objects.";
+           reference
+             "RFC 9046: Babel Information Model, Section 3.3";
+
+           leaf reference {
+             type if:interface-ref;
+             description
+               "References the name of the interface over which Babel
+                packets are sent and received.";
+             reference
+               "RFC 9046: 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 9046: Babel Information Model, Section 3.3";
+           }
+
+           leaf metric-algorithm {
+             type identityref {
+               base metric-comp-algorithms;
+             }
+             mandatory true;
+             description
+               "Indicates the metric computation algorithm used on this
+                interface. The value MUST be one of those identities
+                based on 'metric-comp-algorithms'.";
+             reference
+               "RFC 9046: Babel Information Model, Section 3.3";
+           }
+
+           leaf split-horizon {
+             type boolean;
+             description
+               "Indicates whether or not the split-horizon optimization
+                is used when calculating metrics on this interface.
+                A value of 'true' indicates the split-horizon
+                optimization is used.";
+             reference
+               "RFC 9046: Babel Information Model, Section 3.3";
+           }
+
+           leaf mcast-hello-seqno {
+             type uint16;
+             config false;
+             description
+               "The current sequence number in use for multicast Hellos
+                sent on this interface.";
+             reference
+               "RFC 9046: Babel Information Model, Section 3.3";
+           }
+
+           leaf mcast-hello-interval {
+             type uint16;
+             units "centiseconds";
+             description
+               "The current multicast Hello interval in use for Hellos
+                sent on this interface.";
+             reference
+               "RFC 9046: Babel Information Model, Section 3.3";
+           }
+
+           leaf update-interval {
+             type uint16;
+             units "centiseconds";
+             description
+               "The current update interval in use for this interface.
+                Units are centiseconds.";
+             reference
+               "RFC 9046: Babel Information Model, Section 3.3";
+           }
+
+           leaf mac-enable {
+             type boolean;
+             description
+               "Indicates whether the MAC security mechanism is enabled
+                ('true') or disabled ('false').";
+             reference
+               "RFC 9046: Babel Information Model, Section 3.3";
+           }
+
+           leaf-list mac-key-sets {
+             type leafref {
+               path "../../mac-key-set/name";
+             }
+             description
+               "List of references to the MAC entries that apply
+                to this interface. When an interface instance is
+                created, all MAC instances with default-apply 'true'
+                will be included in this list.";
+             reference
+               "RFC 9046: Babel Information Model, Section 3.3";
+           }
+
+           leaf mac-verify {
+             type boolean;
+             description
+               "A boolean flag indicating whether MACs 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 MAC.";
+             reference
+               "RFC 9046: 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 9046: Babel Information Model, Section 3.3";
+           }
+
+           leaf-list dtls-certs {
+             type leafref {
+               path "../../dtls/name";
+             }
+             description
+               "List of references to the dtls entries that apply to
+                this interface.  When an interface instance
+                is created, all dtls instances with default-apply
+                'true' will be included in this list.";
+             reference
+               "RFC 9046: Babel Information Model, Section 3.3";
+           }
+
+           leaf dtls-cached-info {
+             type boolean;
+             description
+               "Indicates whether the cached_info extension is enabled.
+                The extension is enabled for inclusion in ClientHello
+                and ServerHello messages if the value is 'true'.";
+             reference
+               "RFC 9046: Babel Information Model, Section 3.3
+                RFC 8968: Babel Routing Protocol over
+                Datagram Transport Layer Security, Appendix A";
+           }
+
+           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 the 'type' attribute
+                in the list 'certs' of the list 'dtls'
+                (../../dtls/certs/type). This list is used to populate
+                the server_certificate_type extension in a ClientHello.
+                Values that are present in at least one instance in the
+                certs object under dtls of a referenced dtls instance
+                and that have a non-empty private key will be used to
+                populate the client_certificate_type extension in a
+                ClientHello.";
+             reference
+               "RFC 9046: Babel Information Model, Section 3.3
+                RFC 8968: Babel Routing Protocol over
+                Datagram Transport Layer Security, Appendix A";
+           }
+
+           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 9046: 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
+                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 9046: Babel Information Model, Section 3.3
+                libpcap: Libpcap File Format, Wireshark Foundation";
+           }
+
+           container statistics {
+             config false;
+             description
+               "Statistics collection object for this interface.";
+             reference
+               "RFC 9046: Babel Information Model, Section 3.4";
+
+             leaf discontinuity-time {
+               type yang:date-and-time;
+               mandatory true;
+               description
+                 "The time on the most recent occasion at which any one
+                  or more of 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 the local management
+                  subsystem re-initialized itself.";
+             }
+
+             leaf sent-mcast-hello {
+               type yang:counter32;
+               description
+                 "A count of the number of multicast Hello packets sent
+                  on this interface.";
+               reference
+                 "RFC 9046: Babel Information Model, Section 3.4";
+             }
+
+             leaf sent-mcast-update {
+               type yang:counter32;
+               description
+                 "A count of the number of multicast update packets sent
+                  on this interface.";
+               reference
+                 "RFC 9046: Babel Information Model, Section 3.4";
+             }
+
+             leaf sent-ucast-hello {
+               type yang:counter32;
+               description
+                 "A count of the number of unicast Hello packets sent
+                  on this interface.";
+               reference
+                 "RFC 9046: Babel Information Model, Section 3.4";
+             }
+
+             leaf sent-ucast-update {
+               type yang:counter32;
+               description
+                 "A count of the number of unicast update packets sent
+                  on this interface.";
+               reference
+                 "RFC 9046: Babel Information Model, Section 3.4";
+             }
+
+             leaf sent-ihu {
+               type yang:counter32;
+               description
+                 "A count of the number of 'I Heard You' (IHU) packets
+                  sent on this interface.";
+               reference
+                 "RFC 9046: Babel Information Model, Section 3.4";
+             }
+
+             leaf received-packets {
+               type yang:counter32;
+               description
+                 "A count of the number of Babel packets received on
+                  this interface.";
+               reference
+                 "RFC 9046: Babel Information Model, Section 3.4";
+             }
+
+             action reset {
+               description
+                 "The information model (RFC 9046) defines reset
+                  action as a system-wide reset of Babel statistics.
+                  In YANG, the reset action is associated with the
+                  container where the action is defined. In this case,
+                  the action is associated with the statistics container
+                  inside an interface. The action will therefore
+                  reset statistics at an interface level.
+
+                  Implementations that want to support a system-wide
+                  reset of Babel statistics need to call this action
+                  for every instance of the interface.";
+               reference
+                 "RFC 9046: Babel Information Model";
+
+               input {
+                 leaf reset-at {
+                   type yang:date-and-time;
+                   description
+                     "The time when the reset was issued.";
+                 }
+               }
+
+               output {
+                 leaf reset-finished-at {
+                   type yang:date-and-time;
+                   description
+                     "The time when the reset finished.";
+                 }
+               }
+             }
+           }
+
+           list neighbor-objects {
+             key "neighbor-address";
+             config false;
+             description
+               "A set of babel neighbor objects.";
+             reference
+               "RFC 9046: Babel Information Model, Section 3.5";
+
+             leaf neighbor-address {
+               type inet:ip-address;
+               description
+                 "The IPv4 or IPv6 address from which the neighbor sends
+                  packets.";
+               reference
+                 "RFC 9046: 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 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 the most recent Hello for any
+                  Hellos not received); represented as a string of
+                  hex digits encoded in utf-8. A bit that is set
+                  indicates that the corresponding Hello was received,
+                  and a bit that is cleared indicates that the
+                  corresponding Hello was not received.";
+               reference
+                 "RFC 9046: 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 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 the most recent Hello for any
+                  Hellos not received); represented as a string using
+                  hex digits encoded in utf-8 where a '1' bit = Hello
+                  received and a '0' bit = Hello not received.";
+               reference
+                 "RFC 9046: 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 indicate the IHU hold timer for this
+                  neighbor has an expired description.";
+               reference
+                 "RFC 9046: Babel Information Model, Section 3.5";
+             }
+
+             leaf exp-mcast-hello-seqno {
+               type union {
+                 type enumeration {
+                   enum null {
+                     description
+                       "Multicast Hello packets are not expected, or
+                        processing of multicast packets is not
+                        enabled.";
+                   }
+                 }
+                 type uint16;
+               }
+               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 NULL.";
+               reference
+                 "RFC 9046: Babel Information Model, Section 3.5";
+             }
+
+             leaf exp-ucast-hello-seqno {
+               type union {
+                 type enumeration {
+                   enum null {
+                     description
+                       "Unicast Hello packets are not expected, or
+                        processing of unicast packets is not enabled.";
+                   }
+                 }
+                 type uint16;
+               }
+               default "null";
+               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 NULL.";
+               reference
+                 "RFC 9046: Babel Information Model, Section 3.5";
+             }
+
+             leaf ucast-hello-seqno {
+               type union {
+                 type enumeration {
+                   enum null {
+                     description
+                       "Unicast Hello packets are not being sent.";
+                   }
+                 }
+                 type uint16;
+               }
+               default "null";
+               description
+                 "The current sequence number in use for unicast Hellos
+                  sent to this neighbor. If unicast Hellos are not being
+                  sent, this MUST be NULL.";
+               reference
+                 "RFC 9046: 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 9046: Babel Information Model, Section 3.5";
+             }
+
+             leaf rxcost {
+               type uint16;
+               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 9046: 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 are kept in the
+                  neighbor table about the reception of Hellos, and the
+                  txcost is computed from received IHU packets.";
+               reference
+                 "RFC 9046: Babel Information Model, Section 3.5";
+             }
+           }
+         }
+
+         list mac-key-set {
+           key "name";
+
+           description
+             "A MAC key set object. If this object is implemented, it
+              provides access to parameters related to the MAC security
+              mechanism.";
+           reference
+             "RFC 9046: Babel Information Model, Section 3.7";
+
+           leaf name {
+             type string;
+             description
+               "A string that uniquely identifies the MAC object.";
+           }
+
+           leaf default-apply {
+             type boolean;
+             description
+               "A boolean flag indicating whether this object
+                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 mac-key-sets list under
+                the interface. If 'false', this instance is not applied
+                to new interface instances when they are created.";
+             reference
+               "RFC 9046: Babel Information Model, Section 3.7";
+           }
+
+           list keys {
+             key "name";
+             min-elements 1;
+             description
+               "A set of keys objects.";
+             reference
+               "RFC 9046: Babel Information Model, Section 3.8";
+
+             leaf name {
+               type string;
+               description
+                 "A unique name for this MAC 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 9046: Babel Information Model, Section 3.8";
+             }
+
+             leaf use-send {
+               type boolean;
+               mandatory true;
+               description
+                 "Indicates whether this key value is used to compute a
+                  MAC and include that MAC in the sent Babel packet. A
+                  MAC for sent packets is computed using this key if the
+                  value is 'true'. If the value is 'false', this key is
+                  not used to compute a MAC to include in sent Babel
+                  packets.";
+               reference
+                 "RFC 9046: Babel Information Model, Section 3.8";
+             }
+
+             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 MAC is computed from this key for
+                  comparing an incoming packet.";
+               reference
+                 "RFC 9046: Babel Information Model, Section 3.8";
+             }
+
+             leaf value {
+               nacm:default-deny-all;
+               type binary;
+               mandatory true;
+               description
+                 "The value of the MAC key.
+
+                  This value is of a length suitable for the associated
+                  babel-mac-key-algorithm.  If the algorithm is based on
+                  the Hashed Message Authentication Code (HMAC)
+                  construction (RFC 2104), the length MUST be between 0
+                  and an upper limit that is at least the size of the
+                  output length (where the 'HMAC-SHA256' output length
+                  is 32 octets as described in RFC 4868). Longer lengths
+                  MAY be supported but are not necessary if the
+                  management system has the ability to generate a
+                  suitably random value (e.g., by randomly generating a
+                  value or by using a key derivation technique as
+                  recommended in the security considerations of RFC
+                  8967. If the algorithm is 'BLAKE2s-128', the length
+                  MUST be between 0 and 32 bytes inclusive as specified
+                  by RFC 7693.";
+               reference
+                 "RFC 9046: Babel Information Model, Section 3.8
+                  RFC 2104: HMAC: Keyed-Hashing for Message
+                            Authentication
+                  RFC 4868: Using HMAC-SHA-256, HMAC-SHA-384, and
+                            HMAC-SHA-512 with IPsec
+                  RFC 7693: The BLAKE2 Cryptographic Hash and Message
+                            Authentication Code (MAC)
+                  RFC 8967:  MAC Authentication for Babel";
+             }
+
+             leaf algorithm {
+               type identityref {
+                 base mac-algorithms;
+               }
+               mandatory true;
+               description
+                 "The MAC algorithm used with this key. The
+                  value MUST be one of the identities
+                  listed with the base of 'mac-algorithms'.";
+               reference
+                 "RFC 9046: Babel Information Model, Section 3.8";
+             }
+
+             action test {
+               description
+                 "An operation that allows the MAC key and MAC
+                  algorithm to be tested to see if they produce an
+                  expected outcome. Input to this operation is a
+                  binary string and a calculated MAC (also in the
+                  format of a binary string) for the binary string.
+                  The implementation is expected to create a MAC over
+                  the binary string using the value and algorithm.
+                  The output of this operation is a binary indication
+                  that the calculated MAC matched the input MAC
+                  ('true') or the MACs did not match ('false').";
+               reference
+                 "RFC 9046: Babel Information Model, Section 3.8";
+
+               input {
+                 leaf test-string {
+                   type binary;
+                   mandatory true;
+                   description
+                     "Input to this operation is a binary string.
+                      The implementation is expected to create
+                      a MAC over this string using the value and
+                      the algorithm defined as part of the
+                      mac-key-set.";
+                   reference
+                     "RFC 9046: Babel Information Model, Section 3.8";
+                 }
+
+                 leaf mac {
+                   type binary;
+                   mandatory true;
+                   description
+                     "Input to this operation includes a MAC.
+                      The implementation is expected to calculate a MAC
+                      over the string using the value and algorithm of
+                      this key object and compare its calculated MAC to
+                      this input MAC.";
+                   reference
+                     "RFC 9046: Babel Information Model, Section 3.8";
+                 }
+               }
+
+               output {
+                 leaf indication {
+                   type boolean;
+                   mandatory true;
+                   description
+                     "The output of this operation is a binary
+                      indication that the calculated MAC matched the
+                      input MAC ('true') or the MACs did not match
+                      ('false').";
+                   reference
+                     "RFC 9046: Babel Information Model, Section 3.8";
+                 }
+               }
+             }
+           }
+         }
+
+         list dtls {
+           key "name";
+
+           description
+             "A dtls object. If this object is implemented,
+              it provides access to parameters related to the DTLS
+              security mechanism.";
+           reference
+             "RFC 9046: Babel Information Model, Section 3.9";
+
+           leaf name {
+             type string;
+             description
+               "A string that uniquely identifies a dtls object.";
+           }
+
+           leaf default-apply {
+             type boolean;
+             mandatory true;
+             description
+               "A boolean flag indicating whether this object
+                instance is applied to all new interfaces, by default.
+                If 'true', this instance is applied to new interface
+                instances at the time they are created by including it
+                in the dtls-certs list under the interface. If 'false',
+                this instance is not applied to new interface
+                instances when they are created.";
+             reference
+               "RFC 9046: Babel Information Model, Section 3.9";
+           }
+
+           list certs {
+             key "name";
+
+             min-elements 1;
+             description
+               "A set of cert objects. This contains
+                both certificates for this implementation to present
+                for authentication and to accept from others.
+                Certificates with a non-empty private key
+                can be presented by this implementation for
+                authentication.";
+             reference
+               "RFC 9046: Babel Information Model, Section 3.10";
+
+             leaf name {
+               type string;
+               description
+                 "A unique name for this certificate that can be
+                  used to identify the certificate in this object
+                  instance, since the value is too long to be useful
+                  for identification. This value MUST NOT be empty
+                  and can only be provided when this instance is created
+                  (i.e., it is not subsequently writable).";
+               reference
+                 "RFC 9046: Babel Information Model, Section 3.10";
+             }
+
+             leaf value {
+               nacm:default-deny-write;
+               type string;
+               mandatory true;
+               description
+                 "The certificate in Privacy-Enhanced Mail (PEM) format
+                  (RFC 7468). This value can only be provided when this
+                  instance is created and is not subsequently
+                  writable.";
+               reference
+                 "RFC 9046: Babel Information Model, Section 3.10
+                  RFC 7468: Textual Encodings of PKIX, PKCS, and CMS
+                            Structures";
+             }
+
+             leaf type {
+               nacm:default-deny-write;
+               type identityref {
+                 base dtls-cert-types;
+               }
+               mandatory true;
+               description
+                 "The certificate type of this object instance.
+                  The value MUST be the same as one of the
+                  identities listed with the base 'dtls-cert-types'.
+                  This value can only be provided when this
+                  instance is created and is not subsequently
+                  writable.";
+               reference
+                 "RFC 9046: Babel Information Model, Section 3.10";
+             }
+
+             leaf private-key {
+               nacm:default-deny-all;
+               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.";
+               reference
+                 "RFC 9046: Babel Information Model, Section 3.10";
+             }
+
+             leaf algorithm {
+               nacm:default-deny-write;
+               type identityref {
+                 base ct:private-key-format;
+               }
+               mandatory true;
+               description
+                 "Identifies the algorithm identity with which the
+                  private key has been encoded. This value can only be
+                  provided when this instance is created and is not
+                  subsequently writable.";
+             }
+           }
+         }
+         uses routes;
+       }
+     }
+   }
+   <CODE ENDS>
+
+3.  IANA Considerations
+
+3.1.  URI Registration
+
+   IANA has registered the following URI in the "ns" registry of the
+   "IETF XML Registry" [RFC3688].
+
+   URI:  urn:ietf:params:xml:ns:yang:ietf-babel
+   Registrant Contact:  The IESG
+   XML:  N/A; the requested URI is an XML namespace.
+
+3.2.  YANG Module Name Registration
+
+   IANA has registered the following in the "YANG Module Names" registry
+   [RFC6020].
+
+   Name:  ietf-babel
+   Namespace:  urn:ietf:params:xml:ns:yang:ietf-babel
+   Prefix:  babel
+   Reference:  RFC 9647
+
+4.  Security Considerations
+
+   This section is modeled after the template defined in Section 3.7.1
+   of [RFC8407].
+
+   The "ietf-babel" YANG module defines a data model that is designed to
+   be accessed via YANG-based management protocols, such as NETCONF
+   [RFC6241] and RESTCONF [RFC8040].  These protocols have mandatory-to-
+   implement secure transport layers (e.g., Secure Shell (SSH)
+   [RFC4252], TLS [RFC8446], and QUIC [RFC9000]) and mandatory-to-
+   implement mutual authentication.
+
+   The Network Configuration Access Control Model (NACM) [RFC8341]
+   provides the means to restrict access for particular NETCONF users to
+   a preconfigured subset of all available NETCONF protocol operations
+   and content.
+
+   The security considerations outlined here are specific to the YANG
+   data model and do not cover security considerations of the Babel
+   protocol or its security mechanisms in "The Babel Routing Protocol"
+   [RFC8966], "MAC Authentication for the Babel Routing Protocol"
+   [RFC8967], and "Babel Routing Protocol over Datagram Transport Layer
+   Security" [RFC8968].  Each of these has its own Security
+   Considerations section for considerations that are specific to it.
+
+   There are a number of data nodes defined in the YANG module that 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 from a config true perspective:
+
+   'babel':  This container includes an 'enable' parameter that can be
+      used to enable or disable use of Babel on a router.
+
+   'babel/constants':  This container includes configuration parameters
+      that can prevent reachability if misconfigured.
+
+   'babel/interfaces':  This leaf-list has configuration parameters that
+      can enable/disable security mechanisms and change performance
+      characteristics of the Babel protocol.  For example, enabling
+      logging of packets and giving unintended access to the log files
+      gives an attacker detailed knowledge of the network and allows it
+      to launch an attack on the traffic traversing the network device.
+
+   'babel/hmac' and 'babel/dtls':  These contain security credentials
+      that influence whether incoming packets are trusted and whether
+      outgoing packets are produced in such a way that the receiver will
+      treat them as trusted.
+
+   Some of the readable data or config false 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 from a
+   config false perspective:
+
+   'babel':  Access to the information in the various nodes can disclose
+      the network topology.  Additionally, the routes used by a network
+      device may be used to mount a subsequent attack on traffic
+      traversing the network device.
+
+   'babel/hmac' and 'babel/dtls':  These contain security credentials,
+      including private credentials of the router; however, it is
+      required that these values not be readable.
+
+   Some of the RPC operations in this YANG module may be considered
+   sensitive or vulnerable in some network environments.  It is thus
+   important to control access to these operations.  These are the
+   operations and their sensitivity/vulnerability from an RPC operation
+   perspective:
+
+   This model defines two actions.  Resetting the statistics within an
+   interface container would be visible to any monitoring processes,
+   which should be designed to account for the possibility of such a
+   reset.  The "test" action allows for validation that a MAC key and
+   MAC algorithm have been properly configured.  The MAC key is a
+   sensitive piece of information, and it is important to prevent an
+   attacker that does not know the MAC key from being able to determine
+   the MAC value by trying different input parameters.  The "test"
+   action has been designed to not reveal such information directly.
+   Such information might also be revealed indirectly due to side
+   channels such as the time it takes to produce a response to the
+   action.  Implementations SHOULD use a constant-time comparison
+   between the input MAC and the locally generated MAC value for
+   comparison in order to avoid such side channel leakage.
+
+5.  References
+
+5.1.  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>.
+
+   [RFC4252]  Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH)
+              Authentication Protocol", RFC 4252, DOI 10.17487/RFC4252,
+              January 2006, <https://www.rfc-editor.org/info/rfc4252>.
+
+   [RFC4868]  Kelly, S. and S. Frankel, "Using HMAC-SHA-256, HMAC-SHA-
+              384, and HMAC-SHA-512 with IPsec", RFC 4868,
+              DOI 10.17487/RFC4868, May 2007,
+              <https://www.rfc-editor.org/info/rfc4868>.
+
+   [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>.
+
+   [RFC6991]  Schoenwaelder, J., Ed., "Common YANG Data Types",
+              RFC 6991, DOI 10.17487/RFC6991, July 2013,
+              <https://www.rfc-editor.org/info/rfc6991>.
+
+   [RFC7693]  Saarinen, M., Ed. and J. Aumasson, "The BLAKE2
+              Cryptographic Hash and Message Authentication Code (MAC)",
+              RFC 7693, DOI 10.17487/RFC7693, November 2015,
+              <https://www.rfc-editor.org/info/rfc7693>.
+
+   [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>.
+
+   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
+              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
+              May 2017, <https://www.rfc-editor.org/info/rfc8174>.
+
+   [RFC8341]  Bierman, A. and M. Bjorklund, "Network Configuration
+              Access Control Model", STD 91, RFC 8341,
+              DOI 10.17487/RFC8341, March 2018,
+              <https://www.rfc-editor.org/info/rfc8341>.
+
+   [RFC8343]  Bjorklund, M., "A YANG Data Model for Interface
+              Management", RFC 8343, DOI 10.17487/RFC8343, March 2018,
+              <https://www.rfc-editor.org/info/rfc8343>.
+
+   [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,
+              <https://www.rfc-editor.org/info/rfc8349>.
+
+   [RFC8446]  Rescorla, E., "The Transport Layer Security (TLS) Protocol
+              Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
+              <https://www.rfc-editor.org/info/rfc8446>.
+
+   [RFC8966]  Chroboczek, J. and D. Schinazi, "The Babel Routing
+              Protocol", RFC 8966, DOI 10.17487/RFC8966, January 2021,
+              <https://www.rfc-editor.org/info/rfc8966>.
+
+   [RFC8967]  Dô, C., Kolodziejak, W., and J. Chroboczek, "MAC
+              Authentication for the Babel Routing Protocol", RFC 8967,
+              DOI 10.17487/RFC8967, January 2021,
+              <https://www.rfc-editor.org/info/rfc8967>.
+
+   [RFC8968]  Décimo, A., Schinazi, D., and J. Chroboczek, "Babel
+              Routing Protocol over Datagram Transport Layer Security",
+              RFC 8968, DOI 10.17487/RFC8968, January 2021,
+              <https://www.rfc-editor.org/info/rfc8968>.
+
+   [RFC9000]  Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based
+              Multiplexed and Secure Transport", RFC 9000,
+              DOI 10.17487/RFC9000, May 2021,
+              <https://www.rfc-editor.org/info/rfc9000>.
+
+   [RFC9046]  Stark, B. and M. Jethanandani, "Babel Information Model",
+              RFC 9046, DOI 10.17487/RFC9046, June 2021,
+              <https://www.rfc-editor.org/info/rfc9046>.
+
+   [RFC9147]  Rescorla, E., Tschofenig, H., and N. Modadugu, "The
+              Datagram Transport Layer Security (DTLS) Protocol Version
+              1.3", RFC 9147, DOI 10.17487/RFC9147, April 2022,
+              <https://www.rfc-editor.org/info/rfc9147>.
+
+   [RFC9640]  Watsen, K., "YANG Data Types and Groupings for
+              Cryptography", RFC 9640, DOI 10.17487/RFC9640, October
+              2024, <https://www.rfc-editor.org/info/rfc9640>.
+
+5.2.  Informative References
+
+   [RFC2104]  Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
+              Hashing for Message Authentication", RFC 2104,
+              DOI 10.17487/RFC2104, February 1997,
+              <https://www.rfc-editor.org/info/rfc2104>.
+
+   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
+              DOI 10.17487/RFC3688, January 2004,
+              <https://www.rfc-editor.org/info/rfc3688>.
+
+   [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>.
+
+   [RFC7468]  Josefsson, S. and S. Leonard, "Textual Encodings of PKIX,
+              PKCS, and CMS Structures", RFC 7468, DOI 10.17487/RFC7468,
+              April 2015, <https://www.rfc-editor.org/info/rfc7468>.
+
+   [RFC8340]  Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
+              BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
+              <https://www.rfc-editor.org/info/rfc8340>.
+
+   [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,
+              <https://www.rfc-editor.org/info/rfc8342>.
+
+   [RFC8407]  Bierman, A., "Guidelines for Authors and Reviewers of
+              Documents Containing YANG Data Models", BCP 216, RFC 8407,
+              DOI 10.17487/RFC8407, October 2018,
+              <https://www.rfc-editor.org/info/rfc8407>.
+
+   [W3C.REC-xml-20081126]
+              Bray, T., Paoli, J., Sperberg-McQueen, C. M., Maler, E.,
+              and F. Yergeau, "Extensible Markup Language (XML) 1.0
+              (Fifth Edition)", W3C Recommendation REC-xml-20081126,
+              November 2008, <https://www.w3.org/TR/xml/>.
+
+Appendix A.  Tree Diagram and Example Configurations
+
+   This section is devoted to including a complete tree diagram and
+   examples that demonstrate how Babel can be configured.
+
+   Note that various examples are encoded using Extensible Markup
+   Language (XML) [W3C.REC-xml-20081126].
+
+A.1.  Complete Tree Diagram
+
+   This section includes the complete tree diagram for the Babel YANG
+   module.
+
+   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 seqno?                uint16
+          +--rw statistics-enabled?   boolean
+          +--rw constants
+          |  +--rw udp-port?      inet:port-number
+          |  +--rw mcast-group?   inet:ip-address
+          +--rw interfaces* [reference]
+          |  +--rw reference               if:interface-ref
+          |  +--rw enable?                 boolean
+          |  +--rw metric-algorithm        identityref
+          |  +--rw split-horizon?          boolean
+          |  +--ro mcast-hello-seqno?      uint16
+          |  +--rw mcast-hello-interval?   uint16
+          |  +--rw update-interval?        uint16
+          |  +--rw mac-enable?             boolean
+          |  +--rw mac-key-sets*           -> ../../mac-key-set/name
+          |  +--rw mac-verify?             boolean
+          |  +--rw dtls-enable?            boolean
+          |  +--rw dtls-certs*             -> ../../dtls/name
+          |  +--rw dtls-cached-info?       boolean
+          |  +--rw dtls-cert-prefer*       -> ../../dtls/certs/type
+          |  +--rw packet-log-enable?      boolean
+          |  +--ro packet-log?             inet:uri
+          |  +--ro statistics
+          |  |  +--ro discontinuity-time    yang:date-and-time
+          |  |  +--ro sent-mcast-hello?     yang:counter32
+          |  |  +--ro sent-mcast-update?    yang:counter32
+          |  |  +--ro sent-ucast-hello?     yang:counter32
+          |  |  +--ro sent-ucast-update?    yang:counter32
+          |  |  +--ro sent-ihu?             yang:counter32
+          |  |  +--ro received-packets?     yang:counter32
+          |  |  +---x reset
+          |  |     +---w input
+          |  |     |  +---w reset-at?   yang:date-and-time
+          |  |     +--ro output
+          |  |        +--ro reset-finished-at?   yang:date-and-time
+          |  +--ro neighbor-objects* [neighbor-address]
+          |     +--ro neighbor-address         inet:ip-address
+          |     +--ro hello-mcast-history?     string
+          |     +--ro hello-ucast-history?     string
+          |     +--ro txcost?                  int32
+          |     +--ro exp-mcast-hello-seqno?   union
+          |     +--ro exp-ucast-hello-seqno?   union
+          |     +--ro ucast-hello-seqno?       union
+          |     +--ro ucast-hello-interval?    uint16
+          |     +--ro rxcost?                  uint16
+          |     +--ro cost?                    int32
+          +--rw mac-key-set* [name]
+          |  +--rw name             string
+          |  +--rw default-apply?   boolean
+          |  +--rw keys* [name]
+          |     +--rw name          string
+          |     +--rw use-send      boolean
+          |     +--rw use-verify    boolean
+          |     +--rw value         binary
+          |     +--rw algorithm     identityref
+          |     +---x test
+          |        +---w input
+          |        |  +---w test-string    binary
+          |        |  +---w mac            binary
+          |        +--ro output
+          |           +--ro indication    boolean
+          +--rw dtls* [name]
+          |  +--rw name             string
+          |  +--rw default-apply    boolean
+          |  +--rw certs* [name]
+          |     +--rw name           string
+          |     +--rw value          string
+          |     +--rw type           identityref
+          |     +--rw private-key    binary
+          |     +--rw algorithm      identityref
+          +--ro routes* [prefix]
+             +--ro prefix               inet:ip-prefix
+             +--ro router-id?           binary
+             +--ro neighbor?            leafref
+             +--ro received-metric?     union
+             +--ro calculated-metric?   union
+             +--ro seqno?               uint16
+             +--ro next-hop?            union
+             +--ro feasible?            boolean
+             +--ro selected?            boolean
+
+A.2.  Statistics Gathering Enabled
+
+   In this example, interface eth0 is being configured for routing
+   protocol Babel, and statistics gathering is enabled.  For security,
+   HMAC-SHA256 is supported.  Every sent Babel packet is signed with the
+   key value provided, and every received Babel packet is verified with
+   the same key value.
+
+   <?xml version="1.0" encoding="UTF-8"?>
+   <interfaces xmlns="urn:ietf:params:xml:ns:yang:ietf-interfaces"
+               xmlns:ianaift="urn:ietf:params:xml:ns:yang:iana-if-type">
+     <interface>
+       <name>eth0</name>
+       <type>ianaift:ethernetCsmacd</type>
+       <enabled>true</enabled>
+     </interface>
+   </interfaces>
+   <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>
+           <statistics-enabled>true</statistics-enabled>
+           <interfaces>
+             <reference>eth0</reference>
+             <metric-algorithm>two-out-of-three</metric-algorithm>
+             <split-horizon>true</split-horizon>
+           </interfaces>
+           <mac-key-set>
+             <name>hmac-sha256</name>
+             <keys>
+               <name>hmac-sha256-keys</name>
+               <use-send>true</use-send>
+               <use-verify>true</use-verify>
+               <value>base64encodedvalue==</value>
+               <algorithm>hmac-sha256</algorithm>
+             </keys>
+           </mac-key-set>
+         </babel>
+       </control-plane-protocol>
+     </control-plane-protocols>
+   </routing>
+
+A.3.  Automatic Detection of Properties
+
+   In this example, babeld is configured on two interfaces:
+
+      interface eth0
+      interface wlan0
+
+   This says to run Babel on interfaces eth0 and wlan0.  Babeld will
+   automatically detect that eth0 is wired and wlan0 is wireless and
+   will configure the right parameters automatically.
+
+   <?xml version="1.0" encoding="UTF-8"?>
+   <interfaces xmlns="urn:ietf:params:xml:ns:yang:ietf-interfaces"
+               xmlns:ianaift="urn:ietf:params:xml:ns:yang:iana-if-type">
+     <interface>
+       <name>eth0</name>
+       <type>ianaift:ethernetCsmacd</type>
+       <enabled>true</enabled>
+     </interface>
+     <interface>
+       <name>wlan0</name>
+       <type>ianaift:ieee80211</type>
+       <enabled>true</enabled>
+     </interface>
+   </interfaces>
+   <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>
+           <interfaces>
+             <reference>eth0</reference>
+             <enable>true</enable>
+             <metric-algorithm>two-out-of-three</metric-algorithm>
+             <split-horizon>true</split-horizon>
+           </interfaces>
+           <interfaces>
+             <reference>wlan0</reference>
+             <enable>true</enable>
+             <metric-algorithm>etx</metric-algorithm>
+             <split-horizon>false</split-horizon>
+           </interfaces>
+         </babel>
+       </control-plane-protocol>
+     </control-plane-protocols>
+   </routing>
+
+A.4.  Override Default Properties
+
+   In this example, babeld is configured on three interfaces:
+
+      interface eth0
+      interface eth1 type wireless
+      interface tun0 type tunnel
+
+   Here, interface eth1 is an Ethernet bridged to a wireless radio, so
+   babeld's autodetection fails, and the interface type needs to be
+   configured manually.  Tunnels are not detected automatically, so this
+   needs to be specified.
+
+   This is equivalent to the following:
+
+      interface eth0 metric-algorithm 2-out-of-3 split-horizon true
+      interface eth1 metric-algorithm etx split-horizon false
+      interface tun0 metric-algorithm 2-out-of-3 split-horizon true
+
+   <?xml version="1.0" encoding="UTF-8"?>
+   <interfaces xmlns="urn:ietf:params:xml:ns:yang:ietf-interfaces"
+               xmlns:ianaift="urn:ietf:params:xml:ns:yang:iana-if-type">
+     <interface>
+       <name>eth0</name>
+       <type>ianaift:ethernetCsmacd</type>
+       <enabled>true</enabled>
+     </interface>
+     <interface>
+       <name>eth1</name>
+       <type>ianaift:ethernetCsmacd</type>
+       <enabled>true</enabled>
+     </interface>
+     <interface>
+       <name>tun0</name>
+       <type>ianaift:tunnel</type>
+       <enabled>true</enabled>
+     </interface>
+   </interfaces>
+   <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>
+           <interfaces>
+             <reference>eth0</reference>
+             <enable>true</enable>
+             <metric-algorithm>two-out-of-three</metric-algorithm>
+             <split-horizon>true</split-horizon>
+           </interfaces>
+           <interfaces>
+             <reference>eth1</reference>
+             <enable>true</enable>
+             <metric-algorithm>etx</metric-algorithm>
+             <split-horizon>false</split-horizon>
+           </interfaces>
+           <interfaces>
+             <reference>tun0</reference>
+             <enable>true</enable>
+             <metric-algorithm>two-out-of-three</metric-algorithm>
+             <split-horizon>true</split-horizon>
+           </interfaces>
+         </babel>
+       </control-plane-protocol>
+     </control-plane-protocols>
+   </routing>
+
+A.5.  Configuring Other Properties
+
+   In this example, two interfaces are configured for babeld:
+
+      interface eth0
+      interface ppp0 hello-interval 30 update-interval 120
+
+   Here, ppp0 is a metered 3G link used for fallback connectivity.  It
+   runs with much higher than default time constants in order to avoid
+   control traffic as much as possible.
+
+   <?xml version="1.0" encoding="UTF-8"?>
+   <interfaces xmlns="urn:ietf:params:xml:ns:yang:ietf-interfaces"
+               xmlns:ianaift="urn:ietf:params:xml:ns:yang:iana-if-type">
+     <interface>
+       <name>eth0</name>
+       <type>ianaift:ethernetCsmacd</type>
+       <enabled>true</enabled>
+     </interface>
+     <interface>
+       <name>ppp0</name>
+       <type>ianaift:ppp</type>
+       <enabled>true</enabled>
+     </interface>
+   </interfaces>
+   <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>
+           <interfaces>
+             <reference>eth0</reference>
+             <enable>true</enable>
+             <metric-algorithm>two-out-of-three</metric-algorithm>
+             <split-horizon>true</split-horizon>
+           </interfaces>
+           <interfaces>
+             <reference>ppp0</reference>
+             <enable>true</enable>
+             <mcast-hello-interval>30</mcast-hello-interval>
+             <update-interval>120</update-interval>
+             <metric-algorithm>two-out-of-three</metric-algorithm>
+           </interfaces>
+         </babel>
+       </control-plane-protocol>
+     </control-plane-protocols>
+   </routing>
+
+Acknowledgements
+
+   Juliusz Chroboczek provided most of the example configurations for
+   babel that are shown in Appendix A.
+
+Authors' Addresses
+
+   Mahesh Jethanandani
+   Kloud Services
+   California
+   United States of America
+   Email: mjethanandani@gmail.com
+
+
+   Barbara Stark
+   AT&T
+   Atlanta, GA
+   United States of America
+   Email: barbara.stark@att.com