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+Internet Engineering Task Force (IETF)                          B. Stark
+Request for Comments: 9046                                          AT&T
+Category: Informational                                  M. Jethanandani
+ISSN: 2070-1721                                           Kloud Services
+                                                               June 2021
+
+
+                        Babel Information Model
+
+Abstract
+
+   The Babel information model provides structured data elements for a
+   Babel implementation reporting its current state and may allow
+   limited configuration of some such data elements.  This information
+   model can be used as a basis for creating data models under various
+   data modeling regimes.  This information model only includes
+   parameters and parameter values useful for managing Babel over IPv6.
+
+Status of This Memo
+
+   This document is not an Internet Standards Track specification; it is
+   published for informational purposes.
+
+   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).  Not all documents
+   approved by the IESG are candidates for any level of Internet
+   Standard; see 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/rfc9046.
+
+Copyright Notice
+
+   Copyright (c) 2021 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
+     1.1.  Requirements Language
+     1.2.  Notation
+   2.  Overview
+   3.  The Information Model
+     3.1.  Definition of babel-information-obj
+     3.2.  Definition of babel-constants-obj
+     3.3.  Definition of babel-interface-obj
+     3.4.  Definition of babel-if-stats-obj
+     3.5.  Definition of babel-neighbor-obj
+     3.6.  Definition of babel-route-obj
+     3.7.  Definition of babel-mac-key-set-obj
+     3.8.  Definition of babel-mac-key-obj
+     3.9.  Definition of babel-dtls-cert-set-obj
+     3.10. Definition of babel-dtls-cert-obj
+   4.  Extending the Information Model
+   5.  Security Considerations
+   6.  IANA Considerations
+   7.  References
+     7.1.  Normative References
+     7.2.  Informative References
+   Acknowledgements
+   Authors' Addresses
+
+1.  Introduction
+
+   Babel is a loop-avoiding, distance-vector routing protocol defined in
+   [RFC8966].  [RFC8967] defines a security mechanism that allows Babel
+   packets to be cryptographically authenticated, and [RFC8968] defines
+   a security mechanism that allows Babel packets to be both
+   authenticated and encrypted.  This document describes an information
+   model for Babel (including implementations using one or both of these
+   security mechanisms) that can be used to create management protocol
+   data models (such as a NETCONF [RFC6241] YANG [RFC7950] data model).
+
+   Due to the simplicity of the Babel protocol, most of the information
+   model is focused on reporting the Babel protocol operational state,
+   and very little of that is considered mandatory to implement for an
+   implementation claiming compliance with this information model.  Some
+   parameters may be configurable.  However, it is up to the Babel
+   implementation whether to allow any of these to be configured within
+   its implementation.  Where the implementation does not allow
+   configuration of these parameters, it MAY still choose to expose them
+   as read-only.
+
+   The information model is presented using a hierarchical structure.
+   This does not preclude a data model based on this information model
+   from using a referential or other structure.
+
+   This information model only includes parameters and parameter values
+   useful for managing Babel over IPv6.  This model has no parameters or
+   values specific to operating Babel over IPv4, even though [RFC8966]
+   does define a multicast group for sending and listening to multicast
+   announcements on IPv4.  There is less likelihood of breakage due to
+   inconsistent configuration and increased implementation simplicity if
+   Babel is operated always and only over IPv6.  Running Babel over IPv6
+   requires IPv6 at the link layer and does not need advertised
+   prefixes, router advertisements, or DHCPv6 to be present in the
+   network.  Link-local IPv6 is widely supported among devices where
+   Babel is expected to be used.  Note that Babel over IPv6 can be used
+   for configuration of both IPv4 and IPv6 routes.
+
+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.  Notation
+
+   This document uses a programming-language-like notation to define the
+   properties of the objects of the information model.  An optional
+   property is enclosed by square brackets, [ ], and a list property is
+   indicated by two numbers in angle brackets, <m..n>, where m indicates
+   the minimal number of list elements, and n indicates the maximum
+   number of list elements.  The symbol "*" for n means there are no
+   defined limits on the number of list elements.  Each parameter and
+   object includes an indication of "ro" or "rw". "ro" means the
+   parameter or object is read-only. "rw" means it is read-write.  For
+   an object, read-write means instances of the object can be created or
+   deleted.  If an implementation is allowed to choose to implement a
+   "rw" parameter as read-only, this is noted in the parameter
+   description.
+
+   The object definitions use base types that are defined as follows:
+
+   binary:       A binary string (sequence of octets).
+
+   boolean:      A type representing a Boolean (true or false) value.
+
+   datetime:     A type representing a date and time using the Gregorian
+                 calendar.  The datetime format MUST conform to
+                 [RFC3339], Section 5.6.
+
+   ip-address:   A type representing an IP address.  This type supports
+                 both IPv4 and IPv6 addresses.
+
+   operation:    A type representing a remote procedure call or other
+                 action that can be used to manipulate data elements or
+                 system behaviors.
+
+   reference:    A type representing a reference to another information
+                 or data model element or to some other device resource.
+
+   string:       A type representing a human-readable string consisting
+                 of a (possibly restricted) subset of Unicode and ISO/
+                 IEC 10646 [ISO.10646] characters.
+
+   uint:         A type representing an unsigned integer number.  This
+                 information model does not define a precision.
+
+2.  Overview
+
+   The information model is hierarchically structured as follows:
+
+   +-- babel-information
+      +-- babel-implementation-version
+      +-- babel-enable
+      +-- router-id
+      +-- self-seqno
+      +-- babel-metric-comp-algorithms
+      +-- babel-security-supported
+      +-- babel-mac-algorithms
+      +-- babel-dtls-cert-types
+      +-- babel-stats-enable
+      +-- babel-stats-reset
+      +-- babel-constants
+      |  +-- babel-udp-port
+      |  +-- babel-mcast-group
+      +-- babel-interfaces
+      |  +-- babel-interface-reference
+      |  +-- babel-interface-enable
+      |  +-- babel-interface-metric-algorithm
+      |  +-- babel-interface-split-horizon
+      |  +-- babel-mcast-hello-seqno
+      |  +-- babel-mcast-hello-interval
+      |  +-- babel-update-interval
+      |  +-- babel-mac-enable
+      |  +-- babel-if-mac-key-sets
+      |  +-- babel-mac-verify
+      |  +-- babel-dtls-enable
+      |  +-- babel-if-dtls-cert-sets
+      |  +-- babel-dtls-cached-info
+      |  +-- babel-dtls-cert-prefer
+      |  +-- babel-packet-log-enable
+      |  +-- babel-packet-log
+      |  +-- babel-if-stats
+      |  |  +-- babel-sent-mcast-hello
+      |  |  +-- babel-sent-mcast-update
+      |  |  +-- babel-sent-ucast-hello
+      |  |  +-- babel-sent-ucast-update
+      |  |  +-- babel-sent-IHU
+      |  |  +-- babel-received-packets
+      |  +-- babel-neighbors
+      |     +-- babel-neighbor-address
+      |     +-- babel-hello-mcast-history
+      |     +-- babel-hello-ucast-history
+      |     +-- babel-txcost
+      |     +-- babel-exp-mcast-hello-seqno
+      |     +-- babel-exp-ucast-hello-seqno
+      |     +-- babel-ucast-hello-seqno
+      |     +-- babel-ucast-hello-interval
+      |     +-- babel-rxcost
+      |     +-- babel-cost
+      +-- babel-routes
+      |  +-- babel-route-prefix
+      |  +-- babel-route-prefix-length
+      |  +-- babel-route-router-id
+      |  +-- babel-route-neighbor
+      |  +-- babel-route-received-metric
+      |  +-- babel-route-calculated-metric
+      |  +-- babel-route-seqno
+      |  +-- babel-route-next-hop
+      |  +-- babel-route-feasible
+      |  +-- babel-route-selected
+      +-- babel-mac-key-sets
+      |  +-- babel-mac-default-apply
+      |  +-- babel-mac-keys
+      |     +-- babel-mac-key-name
+      |     +-- babel-mac-key-use-send
+      |     +-- babel-mac-key-use-verify
+      |     +-- babel-mac-key-value
+      |     +-- babel-mac-key-algorithm
+      |     +-- babel-mac-key-test
+      +-- babel-dtls-cert-sets
+         +-- babel-dtls-default-apply
+         +-- babel-dtls-certs
+            +-- babel-cert-name
+            +-- babel-cert-value
+            +-- babel-cert-type
+            +-- babel-cert-private-key
+
+   Most parameters are read-only.  The following is a descriptive list
+   of the parameters that are not required to be read-only:
+
+   *  enable/disable Babel
+
+   *  create/delete Babel Message Authentication Code (MAC) Key sets
+
+   *  create/delete Babel Certificate sets
+
+   *  enable/disable statistics collection
+
+   *  Constant: UDP port
+
+   *  Constant: IPv6 multicast group
+
+   *  Interface: enable/disable Babel on this interface
+
+   *  Interface: metric algorithm
+
+   *  Interface: split horizon
+
+   *  Interface: sets of MAC keys
+
+   *  Interface: verify received MAC packets
+
+   *  Interface: set of certificates for use with DTLS
+
+   *  Interface: use cached info extensions
+
+   *  Interface: preferred order of certificate types
+
+   *  Interface: enable/disable packet log
+
+   *  MAC-keys: create/delete entries
+
+   *  MAC-keys: key used for sent packets
+
+   *  MAC-keys: key used to verify packets
+
+   *  DTLS-certs: create/delete entries
+
+   The following parameters are required to return no value when read:
+
+   *  MAC key values
+
+   *  DTLS private keys
+
+   Note that this overview is intended simply to be informative and is
+   not normative.  If there is any discrepancy between this overview and
+   the detailed information model definitions in subsequent sections,
+   the error is in this overview.
+
+3.  The Information Model
+
+3.1.  Definition of babel-information-obj
+
+   object {
+        string                    ro babel-implementation-version;
+        boolean                   rw babel-enable;
+        binary                    ro babel-self-router-id;
+       [uint                      ro babel-self-seqno;]
+        string                    ro babel-metric-comp-algorithms<1..*>;
+        string                    ro babel-security-supported<0..*>;
+       [string                    ro babel-mac-algorithms<1..*>;]
+       [string                    ro babel-dtls-cert-types<1..*>;]
+       [boolean                   rw babel-stats-enable;]
+       [operation                    babel-stats-reset;]
+        babel-constants-obj       ro babel-constants;
+        babel-interface-obj       ro babel-interfaces<0..*>;
+        babel-route-obj           ro babel-routes<0..*>;
+       [babel-mac-key-set-obj     rw babel-mac-key-sets<0..*>;]
+       [babel-dtls-cert-set-obj   rw babel-dtls-cert-sets<0..*>;]
+   } babel-information-obj;
+
+   babel-implementation-version:  The name and version of this
+      implementation of the Babel protocol.
+
+   babel-enable:  When written, it configures whether the protocol
+      should be enabled (true) or disabled (false).  A read from the
+      running or intended datastore indicates the configured
+      administrative value of whether the protocol is enabled (true) or
+      not (false).  A read from the operational datastore indicates
+      whether the protocol is actually running (true) or not (i.e., it
+      indicates the operational state of the protocol).  A data model
+      that does not replicate parameters for running and operational
+      datastores can implement this as two separate parameters.  An
+      implementation MAY choose to expose this parameter as read-only
+      ("ro").
+
+   babel-self-router-id:  The router-id used by this instance of the
+      Babel protocol to identify itself.  [RFC8966] describes this as an
+      arbitrary string of 8 octets.
+
+   babel-self-seqno:  The current sequence number included in route
+      updates for routes originated by this node.  This is a 16-bit
+      unsigned integer.
+
+   babel-metric-comp-algorithms:  List of supported cost computation
+      algorithms.  Possible values include "2-out-of-3", as described in
+      [RFC8966], Appendix A.2.1, and "ETX", as described in [RFC8966],
+      Appendix A.2.2.
+
+   babel-security-supported:  List of supported security mechanisms.
+      Possible values include "MAC" to indicate support of [RFC8967] and
+      "DTLS" to indicate support of [RFC8968].
+
+   babel-mac-algorithms:  List of supported MAC computation algorithms.
+      Possible values include "HMAC-SHA256" and "BLAKE2s-128" to
+      indicate support for algorithms indicated in [RFC8967].
+
+   babel-dtls-cert-types:  List of supported certificate types.
+      Possible values include "X.509" and "RawPublicKey" to indicate
+      support for types indicated in [RFC8968].
+
+   babel-stats-enable:  Indicates whether statistics collection is
+      enabled (true) or disabled (false) on all interfaces.  When
+      enabled, existing statistics values are not cleared and will be
+      incremented as new packets are counted.
+
+   babel-stats-reset:  An operation that resets all babel-if-stats
+      parameters to zero.  This operation has no input or output
+      parameters.
+
+   babel-constants:  A babel-constants-obj object.
+
+   babel-interfaces:  A set of babel-interface-obj objects.
+
+   babel-routes:  A set of babel-route-obj objects.  Contains the routes
+      known to this node.
+
+   babel-mac-key-sets:  A set of babel-mac-key-set-obj objects.  If this
+      object is implemented, it provides access to parameters related to
+      the MAC security mechanism.  An implementation MAY choose to
+      expose this object as read-only ("ro").
+
+   babel-dtls-cert-sets:  A set of babel-dtls-cert-set-obj objects.  If
+      this object is implemented, it provides access to parameters
+      related to the DTLS security mechanism.  An implementation MAY
+      choose to expose this object as read-only ("ro").
+
+3.2.  Definition of babel-constants-obj
+
+   object {
+        uint         rw babel-udp-port;
+       [ip-address   rw babel-mcast-group;]
+   } babel-constants-obj;
+
+   babel-udp-port:  UDP port for sending and listening for Babel
+      packets.  Default is 6696.  An implementation MAY choose to expose
+      this parameter as read-only ("ro").  This is a 16-bit unsigned
+      integer.
+
+   babel-mcast-group:  Multicast group for sending and listening to
+      multicast announcements on IPv6.  Default is ff02::1:6.  An
+      implementation MAY choose to expose this parameter as read-only
+      ("ro").
+
+3.3.  Definition of babel-interface-obj
+
+   object {
+        reference            ro babel-interface-reference;
+       [boolean              rw babel-interface-enable;]
+        string               rw babel-interface-metric-algorithm;
+       [boolean              rw babel-interface-split-horizon;]
+       [uint                 ro babel-mcast-hello-seqno;]
+       [uint                 ro babel-mcast-hello-interval;]
+       [uint                 ro babel-update-interval;]
+       [boolean              rw babel-mac-enable;]
+       [reference            rw babel-if-mac-key-sets<0..*>;]
+       [boolean              rw babel-mac-verify;]
+       [boolean              rw babel-dtls-enable;]
+       [reference            rw babel-if-dtls-cert-sets<0..*>;]
+       [boolean              rw babel-dtls-cached-info;]
+       [string               rw babel-dtls-cert-prefer<0..*>;]
+       [boolean              rw babel-packet-log-enable;]
+       [reference            ro babel-packet-log;]
+       [babel-if-stats-obj   ro babel-if-stats;]
+        babel-neighbor-obj   ro babel-neighbors<0..*>;
+   } babel-interface-obj;
+
+   babel-interface-reference:  Reference to an interface object that can
+      be used to send and receive IPv6 packets, as defined by the data
+      model (e.g., YANG [RFC7950] and Broadband Forum (BBF) [TR-181]).
+      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.
+
+   babel-interface-enable:  When written, it configures whether the
+      protocol should be enabled (true) or disabled (false) on this
+      interface.  A read from the running or intended datastore
+      indicates the configured administrative value of whether the
+      protocol is enabled (true) or not (false).  A read from the
+      operational datastore indicates whether the protocol is actually
+      running (true) or not (i.e., it indicates the operational state of
+      the protocol).  A data model that does not replicate parameters
+      for running and operational datastores can implement this as two
+      separate parameters.  An implementation MAY choose to expose this
+      parameter as read-only ("ro").
+
+   babel-interface-metric-algorithm:  Indicates the metric computation
+      algorithm used on this interface.  The value MUST be one of those
+      listed in the babel-metric-comp-algorithms parameter.  An
+      implementation MAY choose to expose this parameter as read-only
+      ("ro").
+
+   babel-interface-split-horizon:  Indicates whether or not the split-
+      horizon optimization is used when calculating metrics on this
+      interface.  A value of "true" indicates split-horizon optimization
+      is used.  Split-horizon optimization is described in [RFC8966],
+      Section 3.7.4.  An implementation MAY choose to expose this
+      parameter as read-only ("ro").
+
+   babel-mcast-hello-seqno:  The current sequence number in use for
+      multicast Hellos sent on this interface.  This is a 16-bit
+      unsigned integer.
+
+   babel-mcast-hello-interval:  The current interval in use for
+      multicast Hellos sent on this interface.  Units are centiseconds.
+      This is a 16-bit unsigned integer.
+
+   babel-update-interval:  The current interval in use for all updates
+      (multicast and unicast) sent on this interface.  Units are
+      centiseconds.  This is a 16-bit unsigned integer.
+
+   babel-mac-enable:  Indicates whether the MAC security mechanism is
+      enabled (true) or disabled (false).  An implementation MAY choose
+      to expose this parameter as read-only ("ro").
+
+   babel-if-mac-key-sets:  List of references to the babel-mac-key-sets
+      entries that apply to this interface.  When an interface instance
+      is created, all babel-mac-key-sets instances with babel-mac-
+      default-apply "true" will be included in this list.  An
+      implementation MAY choose to expose this parameter as read-only
+      ("ro").
+
+   babel-mac-verify:  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.  An implementation MAY choose to expose this parameter
+      as read-only ("ro").
+
+   babel-dtls-enable:  Indicates whether the DTLS security mechanism is
+      enabled (true) or disabled (false).  An implementation MAY choose
+      to expose this parameter as read-only ("ro").
+
+   babel-if-dtls-cert-sets:  List of references to the babel-dtls-cert-
+      sets entries that apply to this interface.  When an interface
+      instance is created, all babel-dtls-cert-sets instances with
+      babel-dtls-default-apply "true" will be included in this list.  An
+      implementation MAY choose to expose this parameter as read-only
+      ("ro").
+
+   babel-dtls-cached-info:  Indicates whether the cached_info extension
+      (see [RFC8968], Appendix A) is included in ClientHello and
+      ServerHello packets.  The extension is included if the value is
+      "true".  An implementation MAY choose to expose this parameter as
+      read-only ("ro").
+
+   babel-dtls-cert-prefer:  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 (see [RFC8968], Appendix A)
+      in a ClientHello.  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
+      ClientHello.
+
+   babel-packet-log-enable:  Indicates whether packet logging is enabled
+      (true) or disabled (false) on this interface.
+
+   babel-packet-log:  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 a .pcap file
+      extension SHOULD be supported for packet log files.  Logging is
+      enabled/disabled by babel-packet-log-enable.  Implementations will
+      need to carefully manage and limit memory used by packet logs.
+
+   babel-if-stats:  Statistics collection object for this interface.
+
+   babel-neighbors:  A set of babel-neighbor-obj objects.
+
+3.4.  Definition of babel-if-stats-obj
+
+   object {
+        uint   ro babel-sent-mcast-hello;
+        uint   ro babel-sent-mcast-update;
+        uint   ro babel-sent-ucast-hello;
+        uint   ro babel-sent-ucast-update;
+        uint   ro babel-sent-IHU;
+        uint   ro babel-received-packets;
+   } babel-if-stats-obj;
+
+   babel-sent-mcast-hello:  A count of the number of multicast Hello
+      packets sent on this interface.
+
+   babel-sent-mcast-update:  A count of the number of multicast update
+      packets sent on this interface.
+
+   babel-sent-ucast-hello:  A count of the number of unicast Hello
+      packets sent on this interface.
+
+   babel-sent-ucast-update:  A count of the number of unicast update
+      packets sent on this interface.
+
+   babel-sent-IHU:  A count of the number of "I Heard You" (IHU) packets
+      sent on this interface.
+
+   babel-received-packets:  A count of the number of Babel packets
+      received on this interface.
+
+3.5.  Definition of babel-neighbor-obj
+
+   object {
+        ip-address   ro babel-neighbor-address;
+       [binary       ro babel-hello-mcast-history;]
+       [binary       ro babel-hello-ucast-history;]
+        uint         ro babel-txcost;
+        uint         ro babel-exp-mcast-hello-seqno;
+        uint         ro babel-exp-ucast-hello-seqno;
+       [uint         ro babel-ucast-hello-seqno;]
+       [uint         ro babel-ucast-hello-interval;]
+       [uint         ro babel-rxcost;]
+       [uint         ro babel-cost;]
+   } babel-neighbor-obj;
+
+   babel-neighbor-address:  IPv4 or IPv6 address the neighbor sends
+      packets from.
+
+   babel-hello-mcast-history:  The multicast Hello history of whether or
+      not the multicast Hello packets prior to babel-exp-mcast-hello-
+      seqno were received.  A binary sequence where the most recently
+      received Hello is expressed as a "1" placed in the leftmost bit,
+      with prior bits shifted right (and "0" bits placed between prior
+      Hello bits and most recent Hello for any not-received Hellos).
+      This value should be displayed using hex digits ([0-9a-fA-F]).
+      See [RFC8966], Appendix A.1.
+
+   babel-hello-ucast-history:  The unicast Hello history of whether or
+      not the unicast Hello packets prior to babel-exp-ucast-hello-seqno
+      were received.  A binary sequence where the most recently received
+      Hello is expressed as a "1" placed in the leftmost bit, with prior
+      bits shifted right (and "0" bits placed between prior Hello bits
+      and the most recent Hello for any not-received Hellos).  This
+      value should be displayed using hex digits ([0-9a-fA-F]).  See
+      [RFC8966], Appendix A.1.
+
+   babel-txcost:  Transmission cost value from the last IHU packet
+      received from this neighbor, or the maximum value to indicate the
+      IHU hold timer for this neighbor has expired.  See [RFC8966],
+      Section 3.4.2.  This is a 16-bit unsigned integer.
+
+   babel-exp-mcast-hello-seqno:  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.  This is a
+      16-bit unsigned integer; if the data model uses zero (0) to
+      represent NULL values for unsigned integers, the data model MAY
+      use a different data type that allows differentiation between zero
+      (0) and NULL.
+
+   babel-exp-ucast-hello-seqno:  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.  This is a 16-bit unsigned integer; if
+      the data model uses zero (0) to represent NULL values for unsigned
+      integers, the data model MAY use a different data type that allows
+      differentiation between zero (0) and NULL.
+
+   babel-ucast-hello-seqno:  The current sequence number in use for
+      unicast Hellos sent to this neighbor.  If unicast Hellos are not
+      being sent, this MUST be NULL.  This is a 16-bit unsigned integer;
+      if the data model uses zero (0) to represent NULL values for
+      unsigned integers, the data model MAY use a different data type
+      that allows differentiation between zero (0) and NULL.
+
+   babel-ucast-hello-interval:  The current interval in use for unicast
+      Hellos sent to this neighbor.  Units are centiseconds.  This is a
+      16-bit unsigned integer.
+
+   babel-rxcost:  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.  See
+      [RFC8966], Section 3.4.3.  This is a 16-bit unsigned integer.
+
+   babel-cost:  The link cost, as 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.  This is a 16-bit unsigned integer.
+
+3.6.  Definition of babel-route-obj
+
+   object {
+        ip-address   ro babel-route-prefix;
+        uint         ro babel-route-prefix-length;
+        binary       ro babel-route-router-id;
+        reference    ro babel-route-neighbor;
+        uint         ro babel-route-received-metric;
+        uint         ro babel-route-calculated-metric;
+        uint         ro babel-route-seqno;
+        ip-address   ro babel-route-next-hop;
+        boolean      ro babel-route-feasible;
+        boolean      ro babel-route-selected;
+   } babel-route-obj;
+
+   babel-route-prefix:  Prefix (expressed in IP address format) for
+      which this route is advertised.
+
+   babel-route-prefix-length:  Length of the prefix for which this route
+      is advertised.
+
+   babel-route-router-id:  The router-id of the router that originated
+      this route.
+
+   babel-route-neighbor:  Reference to the babel-neighbors entry for the
+      neighbor that advertised this route.
+
+   babel-route-received-metric:  The metric with which this route was
+      advertised by the neighbor, or the maximum value to indicate the
+      route was recently retracted and is temporarily unreachable (see
+      Section 3.5.4 of [RFC8966]).  This metric will be NULL if the
+      route was not received from a neighbor but was generated through
+      other means.  At least one of the following MUST be non-NULL:
+      babel-route-calculated-metric or babel-route-received-metric.
+      Having both be non-NULL is expected for a route that is received
+      and subsequently advertised.  This is a 16-bit unsigned integer;
+      if the data model uses zero (0) to represent NULL values for
+      unsigned integers, the data model MAY use a different data type
+      that allows differentiation between zero (0) and NULL.
+
+   babel-route-calculated-metric:  A calculated metric for this route.
+      How the metric is calculated is implementation specific.  The
+      maximum value indicates the route was recently retracted and is
+      temporarily unreachable (see Section 3.5.4 of [RFC8966]).  At
+      least one of the following MUST be non-NULL: babel-route-
+      calculated-metric or babel-route-received-metric.  Having both be
+      non-NULL is expected for a route that is received and subsequently
+      advertised.  This is a 16-bit unsigned integer; if the data model
+      uses zero (0) to represent NULL values for unsigned integers, the
+      data model MAY use a different data type that allows
+      differentiation between zero (0) and NULL.
+
+   babel-route-seqno:  The sequence number with which this route was
+      advertised.  This is a 16-bit unsigned integer.
+
+   babel-route-next-hop:  The next-hop address of this route.  This will
+      be empty if this route has no next-hop address.
+
+   babel-route-feasible:  A Boolean flag indicating whether this route
+      is feasible, as defined in Section 3.5.1 of [RFC8966]).
+
+   babel-route-selected:  A Boolean flag indicating whether this route
+      is selected (i.e., whether it is currently being used for
+      forwarding and is being advertised).
+
+3.7.  Definition of babel-mac-key-set-obj
+
+   object {
+        boolean             rw babel-mac-default-apply;
+        babel-mac-key-obj   rw babel-mac-keys<0..*>;
+   } babel-mac-key-set-obj;
+
+   babel-mac-default-apply:  A Boolean flag indicating whether this
+      object instance is applied to all new babel-interfaces instances
+      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-if-mac-key-sets list.  If "false", this instance is
+      not applied to new babel-interfaces instances when they are
+      created.  An implementation MAY choose to expose this parameter as
+      read-only ("ro").
+
+   babel-mac-keys:  A set of babel-mac-key-obj objects.
+
+3.8.  Definition of babel-mac-key-obj
+
+   object {
+        string      rw babel-mac-key-name;
+        boolean     rw babel-mac-key-use-send;
+        boolean     rw babel-mac-key-use-verify;
+        binary      -- babel-mac-key-value;
+        string      rw babel-mac-key-algorithm;
+       [operation      babel-mac-key-test;]
+   } babel-mac-key-obj;
+
+   babel-mac-key-name:  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 MUST NOT be empty and can only
+      be provided when this instance is created (i.e., it is not
+      subsequently writable).  The value MAY be auto-generated if not
+      explicitly supplied when the instance is created.
+
+   babel-mac-key-use-send:  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.  An implementation MAY
+      choose to expose this parameter as read-only ("ro").
+
+   babel-mac-key-use-verify:  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 comparison with the MAC in an
+      incoming packet.  An implementation MAY choose to expose this
+      parameter as read-only ("ro").
+
+   babel-mac-key-value:  The value of the MAC key.  An implementation
+      MUST NOT allow this parameter to be read.  This can be done by
+      always providing an empty string when read, through permissions,
+      or by other means.  This value MUST be provided when this instance
+      is created and is not subsequently writable.  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 [RFC2104], 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
+      [RFC4868]).  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 in Section 7 of [RFC8967]).  If the algorithm is
+      "BLAKE2s-128", the length MUST be between 0 and 32 bytes inclusive
+      as specified by [RFC7693].
+
+   babel-mac-key-algorithm  The name of the MAC algorithm used with this
+      key.  The value MUST be the same as one of the enumerations listed
+      in the babel-mac-algorithms parameter.  An implementation MAY
+      choose to expose this parameter as read-only ("ro").
+
+   babel-mac-key-test:  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 babel-mac-key-value and the babel-mac-key-
+      algorithm.  The output of this operation is a Boolean indication
+      that the calculated MAC matched the input MAC (true) or the MACs
+      did not match (false).
+
+3.9.  Definition of babel-dtls-cert-set-obj
+
+   object {
+        boolean               rw babel-dtls-default-apply;
+        babel-dtls-cert-obj   rw babel-dtls-certs<0..*>;
+   } babel-dtls-cert-set-obj;
+
+   babel-dtls-default-apply:  A Boolean flag indicating whether this
+      object instance is applied to all new babel-interfaces instances
+      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.  An implementation MAY choose to expose this parameter as
+      read-only ("ro").
+
+   babel-dtls-certs:  A set of babel-dtls-cert-obj objects.  This
+      contains both certificates for this implementation to present for
+      authentication and those to accept from others.  Certificates with
+      a non-empty babel-cert-private-key can be presented by this
+      implementation for authentication.
+
+3.10.  Definition of babel-dtls-cert-obj
+
+   object {
+        string      rw babel-cert-name;
+        string      rw babel-cert-value;
+        string      rw babel-cert-type;
+        binary      -- babel-cert-private-key;
+   } babel-dtls-cert-obj;
+
+   babel-cert-name:  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).  The value MAY be
+      auto-generated if not explicitly supplied when the instance is
+      created.
+
+   babel-cert-value:  The certificate in Privacy-Enhanced Mail (PEM)
+      format [RFC7468].  This value MUST be provided when this instance
+      is created and is not subsequently writable.
+
+   babel-cert-type:  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.
+
+   babel-cert-private-key:  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 when read, through permissions,
+      or by other means.  This value can only be provided when this
+      instance is created and is not subsequently writable.
+
+4.  Extending the Information Model
+
+   Implementations MAY extend this information model with other
+   parameters or objects.  For example, an implementation MAY choose to
+   expose Babel route filtering rules by adding a route filtering object
+   with parameters appropriate to how route filtering is done in that
+   implementation.  The precise means used to extend the information
+   model would be specific to the data model the implementation uses to
+   expose this information.
+
+5.  Security Considerations
+
+   This document defines a set of information model objects and
+   parameters that may be exposed and visible from other devices.  Some
+   of these information model objects and parameters may be configured.
+   Securing access to and ensuring the integrity of this data is in
+   scope of and the responsibility of any data model derived from this
+   information model.  Specifically, any YANG [RFC7950] data model is
+   expected to define security exposure of the various parameters, and a
+   [TR-181] data model will be secured by the mechanisms defined for the
+   management protocol used to transport it.
+
+   Misconfiguration (whether unintentional or malicious) can prevent
+   reachability or cause poor network performance (increased latency,
+   jitter, etc.).  Misconfiguration of security credentials can cause a
+   denial-of-service condition for the Babel routing protocol.  The
+   information in this model discloses network topology, which can be
+   used to mount subsequent attacks on traffic traversing the network.
+
+   This information model defines objects that can allow credentials
+   (for this device, for trusted devices, and for trusted certificate
+   authorities) to be added and deleted.  Public keys may be exposed
+   through this model.  This model requires that private keys and MAC
+   keys never be exposed.  Certificates used by [RFC8968]
+   implementations use separate parameters to model the public parts
+   (including the public key) and the private key.
+
+   MAC keys are allowed to be as short as zero length.  This is useful
+   for testing.  It is RECOMMENDED that network operators follow current
+   best practices for key length and generation of keys related to the
+   MAC algorithm associated with the key.  Short (and zero-length) keys
+   are highly susceptible to brute-force attacks and therefore SHOULD
+   NOT be used.  See the security considerations as described in
+   Section 7 of [RFC8967] for additional considerations related to MAC
+   keys; note that there are some specific key value recommendations in
+   the fifth paragraph.  It says that if it is necessary to derive keys
+   from a human-readable passphrase, "only the derived keys should be
+   communicated to the routers" and "the original passphrase itself
+   should be kept on the host used to perform the key generation" (which
+   would be the management system in the case of a remote management
+   protocol).  It also recommends that keys "should have a length of 32
+   octets (both for HMAC-SHA256 and BLAKE2s), and be chosen randomly".
+
+   This information model uses key sets and certification sets to
+   provide a means of grouping keys and certificates.  This makes it
+   easy to use a different set per interface, use the same set for one
+   or more interfaces, have a default set in case a new interface is
+   instantiated, and change keys and certificates as needed.
+
+6.  IANA Considerations
+
+   This document has no IANA actions.
+
+7.  References
+
+7.1.  Normative References
+
+   [ISO.10646]
+              International Organization for Standardization,
+              "Information technology - Universal Coded Character Set
+              (UCS)", ISO Standard 10646:2014, 2014.
+
+   [libpcap]  GitLab, "Libpcap File Format", Wireshark Foundation,
+              November 2020, <https://gitlab.com/wireshark/wireshark/-
+              /wikis/Development/LibpcapFileFormat>.
+
+   [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>.
+
+   [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>.
+
+   [RFC3339]  Klyne, G. and C. Newman, "Date and Time on the Internet:
+              Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,
+              <https://www.rfc-editor.org/info/rfc3339>.
+
+   [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>.
+
+   [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>.
+
+   [RFC7693]  Saarinen, M-J., Ed. and J-P. 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>.
+
+   [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>.
+
+   [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>.
+
+7.2.  Informative References
+
+   [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>.
+
+   [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>.
+
+   [RFC8193]  Burbridge, T., Eardley, P., Bagnulo, M., and J.
+              Schoenwaelder, "Information Model for Large-Scale
+              Measurement Platforms (LMAPs)", RFC 8193,
+              DOI 10.17487/RFC8193, August 2017,
+              <https://www.rfc-editor.org/info/rfc8193>.
+
+   [TR-181]   Broadband Forum, "Device Data Model", Issue: 2 Amendment
+              14, November 2020,
+              <http://cwmp-data-models.broadband-forum.org/>.
+
+Acknowledgements
+
+   Juliusz Chroboczek, Toke Høiland-Jørgensen, David Schinazi, Antonin
+   Décimo, Roman Danyliw, Benjamin Kaduk, Valery Smyslov, Alvaro Retana,
+   Donald Eastlake, Martin Vigoureux, Acee Lindem, and Carsten Bormann
+   have been very helpful in refining this information model.
+
+   The language in the "Notation" section was mostly taken from
+   [RFC8193].
+
+Authors' Addresses
+
+   Barbara Stark
+   AT&T
+   TX
+   United States of America
+
+   Email: barbara.stark@att.com
+
+
+   Mahesh Jethanandani
+   Kloud Services
+   CA
+   United States of America
+
+   Email: mjethanandani@gmail.com