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Information and Data Models for Packet Discard Reporting
draft-ietf-opsawg-discardmodel-09

Document Type Active Internet-Draft (opsawg WG)
Authors John Evans , Oleksandr Pylypenko , Jeffrey Haas , Aviran Kadosh , Mohamed Boucadair
Last updated 2025-09-26 (Latest revision 2025-09-18)
Replaces draft-opsawg-evans-discardmodel
RFC stream Internet Engineering Task Force (IETF)
Intended RFC status Proposed Standard
Formats
Yang Validation 0 errors, 3 warnings
Reviews
Additional resources GitHub Repository
Mailing list discussion
Stream WG state WG Document
Associated WG milestone
Apr 2026
Submit IM and DM for Packet Discard Reporting as Proposed Standard
Document shepherd Diego Lopez
IESG IESG state I-D Exists
Consensus boilerplate Yes
Telechat date (None)
Responsible AD (None)
Send notices to diego.r.lopez@telefonica.com
draft-ietf-opsawg-discardmodel-09
Operations and Management Area Working Group                    J. Evans
Internet-Draft                                              O. Pylypenko
Intended status: Standards Track                                  Amazon
Expires: 22 March 2026                                           J. Haas
                                                        Juniper Networks
                                                               A. Kadosh
                                                     Cisco Systems, Inc.
                                                            M. Boucadair
                                                                  Orange
                                                       18 September 2025

        Information and Data Models for Packet Discard Reporting
                   draft-ietf-opsawg-discardmodel-09

Abstract

   This document defines an Information Model and specifies a
   corresponding YANG data model for packet discard reporting.  The
   Information Model provides an implementation-independent framework
   for classifying packet loss — both intended (e.g., due to policy) and
   unintended (e.g., due to congestion or errors) — to enable automated
   network mitigation of unintended packet loss.  The YANG data model
   specifies an implementation of this framework for network elements.

About This Document

   This note is to be removed before publishing as an RFC.

   The latest revision of this draft can be found at https://o-
   pylypenko.github.io/draft-ietf-opsawg-discardmodel/draft-ietf-opsawg-
   discardmodel.html.  Status information for this document may be found
   at https://datatracker.ietf.org/doc/draft-ietf-opsawg-discardmodel/.

   Discussion of this document takes place on the Operations and
   Management Area Working Group mailing list (mailto:opsawg@ietf.org),
   which is archived at https://mailarchive.ietf.org/arch/browse/
   opsawg/.  Subscribe at https://www.ietf.org/mailman/listinfo/opsawg/.

   Source for this draft and an issue tracker can be found at
   https://github.com/o-pylypenko/draft-ietf-opsawg-discardmodel.

Status of This Memo

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

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

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

   This Internet-Draft will expire on 22 March 2026.

Copyright Notice

   Copyright (c) 2025 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  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Problem Statement . . . . . . . . . . . . . . . . . . . . . .   5
   4.  Information Model . . . . . . . . . . . . . . . . . . . . . .   6
     4.1.  Structure . . . . . . . . . . . . . . . . . . . . . . . .   6
     4.2.  Sub-type Definitions  . . . . . . . . . . . . . . . . . .  10
     4.3.  "ietf-packet-discard-reporting-sx" YANG Module  . . . . .  11
   5.  Data Model  . . . . . . . . . . . . . . . . . . . . . . . . .  25
     5.1.  Structure . . . . . . . . . . . . . . . . . . . . . . . .  25
     5.2.  Implementation Requirements . . . . . . . . . . . . . . .  27
     5.3.  Usage Examples  . . . . . . . . . . . . . . . . . . . . .  28
     5.4.  "ietf-packet-discard-reporting" YANG Module . . . . . . .  29
   6.  Deployment Considerations Experience  . . . . . . . . . . . .  33
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  34
     7.1.  Information Model . . . . . . . . . . . . . . . . . . . .  35
     7.2.  Data Model  . . . . . . . . . . . . . . . . . . . . . . .  35
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  36
   9.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .  36
   10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  36
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  37

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     11.1.  Normative References . . . . . . . . . . . . . . . . . .  37
     11.2.  Informative References . . . . . . . . . . . . . . . . .  37
   Appendix A.  Where Do Packets Get Dropped?  . . . . . . . . . . .  40
   Appendix B.  Example Signal-to-mitigation Action Mapping  . . . .  41
   Appendix C.  Full Information Model Tree  . . . . . . . . . . . .  42
   Appendix D.  Full Data Model Tree . . . . . . . . . . . . . . . .  48
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  52

1.  Introduction

   The primary function of a network is to transport and deliver packets
   according to service level objectives.  For network operators,
   understanding both where and why packet loss occurs within a network
   is essential for effective operation.  Device-reported packet loss
   provides the most direct signal for identifying service impact.
   While certain types of packet loss, such as policy-based discards,
   are intentional and part of normal network operation, unintended
   packet loss can impact customer services.  To automate network
   operations, operators must be able to detect customer-impacting
   packet loss, determine its root cause, and apply appropriate
   mitigation actions.  Precise classification of packet loss is thus
   crucial to ensure that anomalous packet loss is easily detected and
   that the right action is taken to mitigate the impact.  Taking the
   wrong action can make problems worse; for example, removing a
   congested device from service can exacerbate congestion by
   redirecting traffic to other already congested links or devices.

   Existing metrics for reporting packet loss, such as ifInDiscards,
   ifOutDiscards, ifInErrors, and ifOutErrors defined in "The Interfaces
   Group MIB" [RFC2863] and "A YANG Data Model for Interface Management"
   [RFC8343], are insufficient for automating network operations.
   First, they lack precision; for instance, ifInDiscards aggregates all
   discarded inbound packets without specifying the cause, making it
   challenging to distinguish between intended and unintended discards.
   Second, these definitions are ambiguous, leading to inconsistent
   vendor implementations.  For example, in some implementations
   ifInErrors accounts only for errored packets that are dropped, while
   in others, it includes all errored packets, whether they are dropped
   or not.  Many implementations support more discard metrics than
   these, however, they have been inconsistently implemented due to the
   lack of a standardised classification scheme and clear semantics for
   packet loss reporting.  For example, [RFC7270] provides support for
   reporting discards per flow in IP Flow Information Export (IPFIX)
   [RFC7011] using forwardingStatus, however, the defined drop reason
   codes also lack sufficient clarity to facilitate automated root cause
   analysis and impact mitigation (e.g., the "For us" reason code).

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   This document defines an Information Model and specifies a
   corresponding YANG data model for packet loss reporting which address
   these issues.  The Information Model provides precise classification
   of packet loss to enable accurate automated mitigation.  The data
   model specifies a YANG implementation of this framework for network
   elements, while maintaining consistency through clear semantics.

   The scope of this document is limited to reporting packet loss at
   Layer 3 and frames discarded at Layer 2.  This document considers
   only the signals that may trigger automated mitigation actions and
   not how the actions are defined or executed.

   Section 3 describes the problem space and requirements.  Section 4
   defines the Information Model and classification scheme.  Section 5
   specifies the corresponding YANG data model and implementation
   requirements together with a set of usage examples, and the complete
   YANG module definition.  The appendices provide additional context
   and implementation guidance.

2.  Terminology

   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.

   A packet discard accounts for any instance where a packet is dropped
   by a device, regardless of whether the discard was intentional or
   unintentional.

   Intended discards are packets dropped due to deliberate network
   policies or configurations designed to enforce security or Quality of
   Service (QoS).  For example, packets dropped because they match an
   Access Control List (ACL) denying certain traffic types.

   Unintended discards are packets that were dropped, which the network
   operator otherwise intended to deliver, i.e. which indicates an error
   state.  There are many possible reasons for unintended packet loss,
   including: erroring links may corrupt packets in transit; incorrect
   routing tables may result in packets being dropped because they do
   not match a valid route; configuration errors may result in a valid
   packet incorrectly matching an ACL and being dropped.

   Device discard counters do not by themselves establish operator
   intent.  Discards reported under policy (e.g., ACL/policer) indicate
   only that traffic matched a configured rule; such discards may still
   be unintended if the configuration is in error.  Determining intent

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   for policy discards requires external context (e.g., configuration
   validation and change history) which is out of scope for this
   specification.

   Tree diagrams used in this document follow the notation defined in
   [RFC8340].

3.  Problem Statement

   The fundamental problem for network operators is how to automatically
   detect when and where unintended packet loss is occurring and
   determine the appropriate action to mitigate it.  For any network,
   there are a small set of potential actions that can be taken to
   mitigate customer impact when unintended packet loss is detected, for
   example:

   1.  Take a problematic device, link, or set of devices and/or links
       out of service.

   2.  Return a device, link, or set of devices and/or links back into
       service.

   3.  Move traffic to other links or devices to alleviate congestion or
       avoid problematic paths.

   4.  Roll back a recent change to a device that might have caused the
       problem.

   5.  Escalate to a network operator as a last resort when automated
       mitigation is not possible.

   The ability to select the appropriate mitigation action depends on
   four key features of packet loss:

   FEATURE-DISCARD-SCOPE:  Determines which devices, interfaces, and/or
      flows are impacted.

   FEATURE-DISCARD-RATE:  The rate and/or magnitude of the discards,
      indicating the severity and urgency of the problem.  Rate may be
      expressed using absolute (e.g., pps) or relative (e.g., percent)
      values.

   FEATURE-DISCARD-DURATION:  The duration of the discards which helps
      to distinguish transient from persistent issues.

   FEATURE-DISCARD-CLASS:  The type or class of discards, which is

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      crucial for selecting the appropriate of mitigation - for example:
      error discards may require taking faulty components out of
      service; no-buffer discards may require traffic redistribution;
      intended policy discards typically require no automated action

   While FEATURE-DISCARD-SCOPE, FEATURE-DISCARD-RATE, and FEATURE-
   DISCARD-DURATION are implicitly supported by MIB-II [RFC2863] and the
   YANG Data Model for Interface Management [RFC8343], FEATURE-DISCARD-
   CLASS requires a more detailed classification scheme than they
   define.  The following Information Model defines such a
   classification scheme to enable automated mapping from loss signals
   to appropriate mitigation actions.

4.  Information Model

   The Information Model is defined using YANG [RFC7950], with Data
   Structure Extensions [RFC8791], allowing the model to remain abstract
   and decoupled from specific implementations in accordance with
   [RFC3444].  This abstraction supports different data model
   implementations - for example, in YANG, IPFIX [RFC7011], gMNI [gMNI]
   or SNMPv3 [RFC3411] - while ensuring consistency across
   implementations.  Using YANG for the Information Model enables this
   abstraction, leverages the community's familiarity with its syntax,
   and ensures lossless translation to the corresponding YANG data
   model, which is defined in Section 5.

4.1.  Structure

   The Information Model defines a hierarchical classification scheme
   for packet discards, which captures where in a device the discards
   are accounted (component), in which direction they were flowing
   (direction), whether they were successfully processed or discarded
   (type), what protocol layer they belong to (layer), and the specific
   reason for any discards (sub-types).  This structure enables both
   high-level monitoring of total discards and more detailed triage to
   map to mitigation actions.

   The abstract structure of the IM is depicted in Figure 1.  The full
   YANG tree diagram of the IM is provided in Appendix C.

   module: ietf-packet-discard-reporting-sx

     structure packet-discard-reporting:
       +-- control-plane {control-plane-stats}?
       |  +-- traffic* [direction]
       |  |  ...
       |  +-- discards* [direction]
       |     ...

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       +-- interface* [name] {interface-stats}?
       |  +-- name        string
       |  +-- traffic* [direction]
       |  |  +-- direction    identityref
       |  |  +-- l2
       |  |  |  ...
       |  |  +-- l3
       |  |  |  ...
       |  |  +-- qos
       |  |     +-- class* [id]
       |  |        ...
       |  +-- discards* [direction]
       |     +-- direction    identityref
       |     +-- l2
       |     |  ...
       |     +-- l3
       |     |  ...
       |     +-- errors
       |     |  +-- l2
       |     |  |  ...
       |     |  +-- l3
       |     |  |  ...
       |     |  +-- internal
       |     |     ...
       |     +-- policy
       |     |  +-- l2
       |     |  |  ...
       |     |  +-- l3
       |     |     ...
       |     +-- no-buffer
       |        +-- class* [id]
       |           ...
       +-- flow* [direction] {flow-reporting}?
       |  +-- direction    identityref
       |  +-- traffic
       |  |  +-- l2
       |  |  |  ...
       |  |  +-- l3
       |  |  |  ...
       |  |  +-- qos
       |  |     +-- class* [id]
       |  |        ...
       |  +-- discards
       |     +-- l2
       |     |  ...
       |     +-- l3
       |     |  ...
       |     +-- errors

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       |     |  +-- l2
       |     |  |  ...
       |     |  +-- l3
       |     |  |  ...
       |     |  +-- internal
       |     |     ...
       |     +-- policy
       |     |  +-- l2
       |     |  |  ...
       |     |  +-- l3
       |     |     ...
       |     +-- no-buffer
       |        +-- class* [id]
       |           ...
       +-- device {device-stats}?
          +-- traffic
          |  +-- l2
          |  |  ...
          |  +-- l3
          |  |  ...
          |  +-- qos
          |     +-- class* [id]
          |        ...
          +-- discards
             +-- l2
             |  ...
             +-- l3
             |  ...
             +-- errors
             |  +-- l2
             |  |  ...
             |  +-- l3
             |  |  ...
             |  +-- internal
             |     ...
             +-- policy
             |  +-- l2
             |  |  ...
             |  +-- l3
             |     ...
             +-- no-buffer
                +-- class* [id]
                   ...

                    Figure 1: Abstract IM Tree Structure

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   The discard reporting can be organized into several types: control
   plane, interface, flow, and device.  In order to allow for better
   mapping to underlying data models, the IM supports a set of
   "features" to control the supported type.

   A complete classification path follows the pattern:
   component/direction/type/layer/sub-type/sub-sub-type/.../metric.
   Appendix A illustrates where these discards typically occur in a
   network device.  The elements of the tree are defined as follows:

   *  Component:

      -  control-plane: discards of traffic to or from a device's
         control plane.

      -  interface: discards of traffic to or from a specific network
         interface.

      -  flow: discards of traffic associated with a specific traffic
         flow.

      -  device: discards of traffic transiting the device.

   *  Direction:

      -  ingress: counters for incoming packets or frames.

      -  egress: counters for outgoing packets or frames.

   *  Type:

      -  traffic: counters for successfully received or transmitted
         packets or frames.

      -  discards: counters for packets or frames that were dropped.

   *  Layer:

      -  l2: Layer 2 traffic and discards.  This covers both frame and
         byte counts.

      -  l3: Layer 3 traffic and discards.  This covers both packet and
         byte counts.

   The hierarchical structure allows for future extension while
   maintaining backward compatibility.  New discard types can be added
   as new branches without affecting existing implementations.

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   The corresponding YANG module is defined in Section 4.3.

4.2.  Sub-type Definitions

   discards/policy/:  These are intended discards, meaning packets
      dropped by a device due to a configured policy, including: ACLs,
      traffic policers, Reverse Path Forwarding (RPF) checks, DDoS
      protection rules, and explicit null routes.

   discards/error/:  These are unintended discards due to errors in
      processing packets or frames.  There are multiple sub-classes.

   discards/error/l2/rx/:  These are frames discarded due to errors in
      the received Layer 2 frame, including: CRC errors, invalid MAC
      addresses, invalid VLAN tags, frame size violations and other
      malformed frame conditions.

   discards/error/l3/rx/:  These are discards which occur due to errors
      in the received packet, indicating an upstream problem rather than
      an issue with the device dropping the errored packets, including:
      header checksum errors, MTU exceeded, invalid packet errors, i.e.,
      incorrect version, incorrect header length, invalid options and
      other malformed packet conditions.

   discards/error/l3/rx/ttl-expired:  These are discards due to TTL (or
      Hop limit) expiry, which can occur for the following reasons:
      normal trace-route operations, end-system TTL/Hop limit set too
      low, routing loops in the network.

   discards/error/l3/no-route/:  These are discards which occur due to a
      packet not matching any route in the routing table, e.g., which
      may be due to routing configuration errors or may be transient
      discards during convergence.

   discards/error/internal/:  These are discards due to internal device
      issues, including: parity errors in device memory or other
      internal hardware errors.  Any errored discards not explicitly
      assigned to other classes are also accounted for here.

   discards/no-buffer/:  These are discards due to buffer exhaustion,
      i.e. congestion related discards.  These can be tail-drop discards
      or due to an active queue management algorithm, such as RED
      [RED93] or CODEL [RFC8289].

   An example of possible signal-to-mitigation action mapping is
   provided in Appendix B.

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4.3.  "ietf-packet-discard-reporting-sx" YANG Module

   The "ietf-packet-discard-reporting-sx" module uses the "sx" structure
   defined in [RFC8791].

   <CODE BEGINS>
   module ietf-packet-discard-reporting-sx {
     yang-version 1.1;
     namespace
       "urn:ietf:params:xml:ns:yang:ietf-packet-discard-reporting-sx";
     prefix plr-sx;

     import ietf-yang-types {
       prefix yang;
       reference
         "RFC 6991: Common YANG Data Types";
     }
     import ietf-yang-structure-ext {
       prefix sx;
       reference
         "RFC 8791: YANG Data Structure Extensions";
     }

     organization
       "IETF OPSAWG (Operations and Management Area Working Group)";
     contact
       "WG Web:   https://datatracker.ietf.org/wg/opsawg/
        WG List:  mailto:opsawg@ietf.org

        Author:   John Evans
                  <mailto:jevanamz@amazon.co.uk>

        Author:   Oleksandr Pylypenko
                  <mailto:opyl@amazon.com>

        Author:   Jeffrey Haas
                  <mailto:jhaas@juniper.net>

        Author:   Aviran Kadosh
                  <mailto:akadosh@cisco.com>

        Author:   Mohamed Boucadair
                  <mailto:mohamed.boucadair@orange.com>";
     description
       "This module defines an information model for packet discard
        reporting.

        Copyright (c) 2025 IETF Trust and the persons identified as

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        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 XXXX; see the
        RFC itself for full legal notices.";

     revision 2024-06-04 {
       description
         "Initial revision.";
       reference
         "RFC XXXX: Information and Data Models for Packet Discard
                    Reporting";
     }

     /*
      * Features
      */

     feature control-plane-stats {
       description
         "Indicates support of control plane statistics on this
          device.";
     }

     feature interface-stats {
       description
         "Indicates support of interface statistics on this
          device.";
     }

     feature flow-reporting {
       description
         "Indicates support of flow reporting on this device.";
     }

     feature device-stats {
       description
         "Indicates support of global device statistics on this
          device.";
     }

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     /*
      * Identities
      */

     identity direction {
       description
         "Defines a direction for the reported statistics.";
     }

     identity ingress {
       base direction;
       description
         "Reports statistics for the received from the network
          packets.";
     }

     identity egress {
       base direction;
       description
         "Reports statistics for the sent to the network
          packets.";
     }

     identity address-family {
       description
         "Defines a type for the address family.";
     }

     identity ipv4 {
       base address-family;
       description
         "Identity for an IPv4 address family.";
     }

     identity ipv6 {
       base address-family;
       description
         "Identity for an IPv6 address family.";
     }

     identity all {
       base address-family;
       description
         "Identity for all address families.";
     }

     /*
      * Groupings

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      */

     grouping basic-packets {
       description
         "Grouping for Layer 3 packet counters.";
       leaf packets {
         type yang:counter64;
         description
           "Number of Layer 3 packets.";
       }
     }

     grouping basic-packets-bytes {
       description
         "Grouping for Layer 3 packet and byte counters.";
       uses basic-packets;
       leaf bytes {
         type yang:counter64;
         description
           "Number of Layer 3 bytes.";
       }
     }

     grouping basic-frames {
       description
         "Grouping for Layer 2 frame counters.";
       leaf frames {
         type yang:counter64;
         description
           "Number of Layer 2 frames.";
       }
     }

     grouping basic-frames-bytes {
       description
         "Grouping for Layer 2 frame and byte counters.";
       uses basic-frames;
       leaf bytes {
         type yang:counter64;
         description
           "Number of Layer 2 bytes.";
       }
     }

     grouping l2-traffic {
       description
         "Layer 2 traffic counters.";
       uses basic-frames-bytes;

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     }

     grouping ip {
       description
         "Layer 3 traffic counters per address family.";
       list address-family-stat {
         key "address-family";
         description
           "Reports per address family traffic counters.";
         leaf address-family {
           type identityref {
             base address-family;
           }
           description
             "Specifies an address family.";
         }
         uses basic-packets-bytes;
         container unicast {
           description
             "Unicast traffic counters.";
           uses basic-packets-bytes;
         }
         container multicast {
           description
             "Multicast traffic counters.";
           uses basic-packets-bytes;
         }
       }
     }

     grouping l3-traffic {
       description
         "Layer 3 traffic counters.";
       uses ip;
     }

     grouping class-list {
       description
         "Class-based traffic counters.";
       list class {
         key "id";
         min-elements 1;
         description
           "Class traffic counters.";
         leaf id {
           type string;
           description
             "Class identifier.";

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         }
         uses basic-packets-bytes;
       }
     }

     grouping qos {
       description
         "Quality of Service (QoS) traffic counters.";
       container qos {
         presence "QoS statistics are available.";
         description
           "Per-class QoS traffic counters.";
         uses class-list;
       }
     }

     grouping traffic {
       description
         "All traffic counters.";
       container l2 {
         description
           "Layer 2 traffic counters.";
         uses l2-traffic;
       }
       container l3 {
         description
           "Layer 3 traffic counters.";
         uses l3-traffic;
       }
       uses qos;
     }

     grouping errors-l2-rx {
       description
         "Layer 2 ingress frame error discard counters.";
       container rx {
         description
           "Layer 2 ingress frame receive error discard
            counters.";
         leaf frames {
           type yang:counter64;
           description
             "The number of frames discarded due to errors
              with the received frame.";
         }
         leaf crc-error {
           type yang:counter64;
           description

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             "The number of frames discarded due to CRC error.";
         }
         leaf invalid-mac {
           type yang:counter64;
           description
             "The number of frames discarded due to an invalid
              MAC address.";
         }
         leaf invalid-vlan {
           type yang:counter64;
           description
             "The number of frames discarded due to an invalid
              VLAN tag.";
         }
         leaf invalid-frame {
           type yang:counter64;
           description
             "The number of invalid frames discarded due to other
              reasons, not limited to: malformed frames, frame-size
              violations.";
         }
       }
     }

     grouping errors-l3-rx {
       description
         "Layer 3 ingress packet error discard counters.";
       container rx {
         description
           "Layer 3 ingress packet receive error discard
            counters.";
         leaf packets {
           type yang:counter64;
           description
             "The number of Layer 3 packets discarded due to
              errors in the received packet.";
         }
         leaf checksum-error {
           type yang:counter64;
           description
             "The number of received packets discarded due
              to a checksum error.";
         }
         leaf mtu-exceeded {
           type yang:counter64;
           description
             "The number of received packets discarded due to
              MTU exceeded.";

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         }
         leaf invalid-packet {
           type yang:counter64;
           description
             "The number of invalid packets discarded due to other
              reasons, not limited to: invalid packet length, invalid
              header fields, invalid options, invalid protocol version,
              invalid flags or control bits, malformed packets.";
         }
       }
       leaf ttl-expired {
         type yang:counter64;
         description
           "The number of received packets discarded due to
            expired TTL.";
       }
       leaf no-route {
         type yang:counter64;
         description
           "The number of packets discarded due to not matching
            a valid route.";
       }
       leaf invalid-sid {
         type yang:counter64;
         description
           "The number of packets discarded due to an invalid
            Segment Routing (SR) SID.";
       }
       leaf invalid-label {
         type yang:counter64;
         description
           "The number of packets discarded due to an invalid
            MPLS label.";
       }
     }

     grouping errors-l3-int {
       description
         "Internal error discard counters.";
       leaf packets {
         type yang:counter64;
         description
           "The number of packets discarded due to internal
            errors.";
       }
       leaf parity-error {
         type yang:counter64;
         description

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           "The number of packets discarded due to parity
            errors.";
       }
     }

     grouping errors-l2-tx {
       description
         "Layer 2 transmit error discard counters.";
       container tx {
         description
           "Layer 2 transmit frame error discard counters.";
         leaf frames {
           type yang:counter64;
           description
             "The number of Layer 2 frames discarded due to
              errors when transmitting.";
         }
       }
     }

     grouping errors-l3-tx {
       description
         "Layer 3 transmit error discard counters.";
       container tx {
         description
           "Layer 3 transmit packet error discard counters.";
         leaf packets {
           type yang:counter64;
           description
             "The number of Layer 3 packets discarded due to
              errors when transmitting.";
         }
       }
     }

     grouping errors {
       description
         "Error discard counters.";
       container l2 {
         description
           "Layer 2 frame error discard counters.";
         uses errors-l2-rx;
         uses errors-l2-tx;
       }
       container l3 {
         description
           "Layer 3 packet error discard counters.";
         uses errors-l3-rx;

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         uses errors-l3-tx;
       }
       container internal {
         description
           "Internal error discard counters.";
         uses errors-l3-int;
       }
     }

     grouping policy-l2 {
       description
         "Layer 2 policy frame discard counters.";
       leaf frames {
         type yang:counter64;
         description
           "The number of Layer 2 frames discarded due
            to policy.";
       }
       leaf acl {
         type yang:counter64;
         description
           "The number of frames discarded due to Layer 2 ACLs.";
       }
     }

     grouping policy-l3 {
       description
         "Layer 3 policy packet discard counters.";
       leaf packets {
         type yang:counter64;
         description
           "The number of Layer 3 packets discarded due to policy.";
       }
       leaf acl {
         type yang:counter64;
         description
           "The number of packets discarded due to Layer 3 ACLs.";
       }
       container policer {
         description
           "The number of packets discarded due to policer
            violations.";
         uses basic-packets-bytes;
         container classes {
           presence "Per-class policer statistics are available.";
           description
             "Per-class policer discard counters.";
           uses class-list;

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         }
       }
       leaf null-route {
         type yang:counter64;
         description
           "The number of packets discarded due to matching
            a null route.";
       }
       leaf rpf {
         type yang:counter64;
         description
           "The number of packets discarded due to failing
            Reverse Path Forwarding (RPF) check.";
       }
       leaf ddos {
         type yang:counter64;
         description
           "The number of packets discarded due to DDoS
            protection policies.";
       }
     }

     grouping discards {
       description
         "Discard counters.";
       container l2 {
         description
           "Layer 2 frame discard counters.";
         uses l2-traffic;
       }
       container l3 {
         description
           "Layer 3 packet discard counters.";
         uses l3-traffic;
       }
       container errors {
         description
           "Error discard counters.";
         uses errors;
       }
       container policy {
         description
           "Policy-related discard counters.";
         uses policy;
       }
       container no-buffer {
         description
           "Discard counters due to buffer unavailability.";

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         uses qos;
       }
     }

     grouping policy {
       description
         "Policy-related discard counters.";
       container l2 {
         description
           "Layer 2 policy frame discard counters.";
         uses policy-l2;
       }
       container l3 {
         description
           "Layer 3 policy packet discard counters.";
         uses policy-l3;
       }
     }

     grouping device {
       description
         "Device-level traffic and discard counters.";
       container traffic {
         description
           "Traffic counters.";
         uses traffic;
       }
       container discards {
         description
           "Discard counters.";
         uses discards;
       }
     }

     grouping interface {
       description
         "Interface-level traffic and discard counters.";
       list traffic {
         key "direction";
         description
           "Traffic counters.";
         leaf direction {
           type identityref {
             base direction;
           }
           description
             "Specifies a direction.";
         }

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         uses traffic;
       }
       list discards {
         key "direction";
         description
           "Discard counters.";
         leaf direction {
           type identityref {
             base direction;
           }
           description
             "Specifies a direction.";
         }
         uses discards;
       }
     }

     grouping control-plane {
       description
         "Control plane packet counters.";
       list traffic {
         key "direction";
         description
           "Total control plane packets.";
         leaf direction {
           type identityref {
             base direction;
           }
           description
             "Specifies a direction.";
         }
         uses basic-packets-bytes;
       }
       list discards {
         key "direction";
         description
           "Control plane packet discard counters.";
         leaf direction {
           type identityref {
             base direction;
           }
           description
             "Specifies a direction.";
         }
         uses basic-packets-bytes;
         container policy {
           description
             "Number of control plane packets discarded due to policy.";

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           uses basic-packets;
         }
       }
     }

     /*
      * Main structure definition
      */

     sx:structure packet-discard-reporting {
       description
         "Specifies the abstract structure of packet discard
          reporting data.";
       container control-plane {
         if-feature "control-plane-stats";
         description
           "Control plane packet counters.";
         uses control-plane;
       }
       list interface {
         if-feature "interface-stats";
         key "name";
         description
           "Indicates a list of interfaces for which packet
            discard reporting data is provided.";
         leaf name {
           type string;
           description
             "Indicates the name of the interface.";
         }
         uses interface;
       }
       list flow {
         if-feature "flow-reporting";
         key "direction";
         leaf direction {
           type identityref {
             base direction;
           }
           description
             "Specifies a direction.";
         }
         description
           "Flow packet counters.";
         uses device;
       }
       container device {
         if-feature "device-stats";

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         description
           "Device level packet counters.";
         uses device;
       }
     }
   }
   <CODE ENDS>

5.  Data Model

   This data model implements the Information Model defined in Section 4
   for the interface, device, and control-plane components.  This is
   classified as a Network Element model as defined by [RFC1157].

5.1.  Structure

   There is a direct mapping between the Information Model components
   and their data model implementations, with each component in the
   hierarchy represented by corresponding YANG containers and leaf data
   nodes.  The abstract tree is shown in Figure 2.

   module: ietf-packet-discard-reporting

     +--ro control-plane! {control-plane-stats}?
     |  +--ro traffic* [direction]
     |  |  ...
     |  +--ro discards* [direction]
     |     ...
     +--ro interface* [name] {interface-stats}?
     |  +--ro name        string
     |  +--ro traffic* [direction]
     |  |  +--ro direction    identityref
     |  |  +--ro l2
     |  |  |  ...
     |  |  +--ro l3
     |  |  |  ...
     |  |  +--ro qos
     |  |     +--ro class* [id]
     |  |        ...
     |  +--ro discards* [direction]
     |     +--ro direction    identityref
     |     +--ro l2
     |     |  ...
     |     +--ro l3
     |     |  ...
     |     +--ro errors
     |     |  +--ro l2
     |     |  |  ...

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     |     |  +--ro l3
     |     |  |  ...
     |     |  +--ro internal
     |     |     ...
     |     +--ro policy
     |     |  +--ro l2
     |     |  |  ...
     |     |  +--ro l3
     |     |     ...
     |     +--ro no-buffer
     |        +--ro class* [id]
     |           ...
     +--ro device! {device-stats}?
        +--ro traffic
        |  +--ro l2
        |  |  ...
        |  +--ro l3
        |  |  ...
        |  +--ro qos
        |     +--ro class* [id]
        |        ...
        +--ro discards
           +--ro l2
           |  ...
           +--ro l3
           |  ...
           +--ro errors
           |  +--ro l2
           |  |  ...
           |  +--ro l3
           |  |  ...
           |  +--ro internal
           |     ...
           +--ro policy
           |  +--ro l2
           |  |  ...
           |  +--ro l3
           |     ...
           +--ro no-buffer
              +--ro class* [id]
                 ...

                    Figure 2: Abstract DM Tree Structure

   The full tree structure is provided in Appendix D.

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5.2.  Implementation Requirements

   The following requirements apply to the implementation of the data
   model and are intended to ensure consistent implementation across
   different vendors and platforms while allowing for platform-specific
   optimisations where needed.  While the model defines a comprehensive
   set of counters and statistics, implementations MAY support a subset
   of the defined features based on device capabilities and operational
   requirements.  However, implementations MUST clearly document which
   features are supported and how they map to the model.

   Requirements 1-13 relate to packets forwarded or discarded by the
   device, while requirement 14 relates to packets destined for or
   originating from the device:

   1.   All instances of Layer 2 frame or Layer 3 packet receipt,
        transmission, and discards MUST be accounted for.

   2.   All instances of Layer 2 frame or Layer 3 packet receipt,
        transmission, and discards SHOULD be attributed to the physical
        or logical interface of the device where they occur.  Where they
        cannot be attributed to the interface, they MUST be attributed
        to the device.

   3.   An individual frame MUST only be accounted for by either the
        Layer 2 traffic class or the Layer 2 discard classes within a
        single direction or context, i.e., ingress or egress or device.
        This is to avoid double counting.

   4.   An individual packet MUST only be accounted for by either the
        Layer 3 traffic class or the Layer 3 discard classes within a
        single direction or context, i.e., ingress or egress or device.
        This is to avoid double counting.

   5.   A frame accounted for at Layer 2 SHOULD NOT be accounted for at
        Layer 3 and vice versa.  An implementation MUST indicate which
        layers traffic and discards are counted against.  This is to
        avoid double counting.

   6.   The aggregate Layer 2 and Layer 3 traffic and discard classes
        SHOULD account for all underlying frames or packets received,
        transmitted, and discarded across all other classes.

   7.   The aggregate QoS traffic and no-buffer discard classes MUST
        account for all underlying packets received, transmitted, and
        discarded across all other classes.

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   8.   In addition to the Layer 2 and Layer 3 aggregate classes, an
        individual discarded packet MUST only account against a single
        error, policy, or no-buffer discard subclass.

   9.   When there are multiple reasons for discarding a packet, the
        ordering of discard class reporting MUST be defined.

   10.  If Diffserv [RFC2475] is not used, no-buffer discards SHOULD be
        reported as class[id="0"], which represents the default class.

   11.  When traffic is mirrored, the discard metrics MUST account for
        the original traffic rather than the reflected traffic.

   12.  NoBuffer discards can be realized differently with different
        memory architectures.  Whether a NoBuffer discard is attributed
        to ingress or egress can differ accordingly.  For successful
        auto-mitigation, discards due to an egress interface congestion
        MUST be able to be reported on egress, while discards due to
        device-level congestion (e.g., due to exceeding the device
        forwarding rate) MUST be able to be ingress.

   13.  When the ingress and egress headers differ—for example, at a
        tunnel endpoint—the discard class attribution MUST relate to the
        outer header at the point of discard.

   14.  Traffic to the device control plane has its own class.  However,
        traffic from the device control plane MUST be accounted for in
        the same way as other egress traffic.

5.3.  Usage Examples

   If all of the requirements listed in Section 5.2 are met, a "good"
   unicast IPv4 packet received would increment:

   *  interface/ingress/traffic/l3/v4/unicast/packets

   *  interface/ingress/traffic/l3/v4/unicast/bytes

   *  interface/ingress/traffic/qos/class[id="0"]/packets

   *  interface/ingress/traffic/qos/class[id="0"]/bytes

   A received unicast IPv6 packet discarded due to Hop Limit expiry
   would increment:

   *  interface/ingress/discards/l3/v6/unicast/packets

   *  interface/ingress/discards/l3/v6/unicast/bytes

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   *  interface/ingress/discards/l3/rx/ttl-expired/packets

   An IPv4 packet discarded on egress due to no buffers would increment:

   *  interface/egress/discards/l3/v4/unicast/packets

   *  interface/egress/discards/l3/v4/unicast/bytes

   *  interface/egress/discards/no-buffer/class[id="0"]/packets

   *  interface/egress/discards/no-buffer/class[id="0"]/bytes

   A multicast IPv6 packet dropped due to RPF check failure would
   increment:

   *  interface/ingress/discards/l3/v6/multicast/packets

   *  interface/ingress/discards/l3/v6/multicast/bytes

   *  interface/ingress/discards/policy/l3/rpf/packets

   A "good" Layer-2 frame received would increment: -
   interface/ingress/traffic/l2/frames - interface/ingress/traffic/l2/
   bytes - interface/ingress/traffic/qos/class[id="0"]/packets -
   interface/ingress/traffic/qos/class[id="0"]/bytes

5.4.  "ietf-packet-discard-reporting" YANG Module

   The "ietf-packet-discard-reporting" module imports "ietf-packet-
   discard-reporting-sx", "ietf-netconf-acm" [RFC8341], "ietf-
   interfaces" [RFC8343], "ietf-routing" [RFC8349], and "ietf-logical-
   network-element" [RFC8530].

   <CODE BEGINS>
   module ietf-packet-discard-reporting {
     yang-version 1.1;
     namespace
       "urn:ietf:params:xml:ns:yang:ietf-packet-discard-reporting";
     prefix plr;

     import ietf-packet-discard-reporting-sx {
       prefix plr-sx;
       reference
         "RFC XXXX: Information and Data Models for Packet Discard
                    Reporting";
     }
     import ietf-netconf-acm {
       prefix nacm;

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       reference
         "RFC 8341: Network Configuration Access Control Model";
     }
     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-logical-network-element {
       prefix lne;
       reference
         "RFC 8530: YANG Model for Logical Network Elements";
     }

     organization
       "IETF OPSAWG (Operations and Management Area Working Group)";
     contact
       "WG Web:   https://datatracker.ietf.org/wg/opsawg/
        WG List:  mailto:opsawg@ietf.org

        Author:   John Evans
                  <mailto:jevanamz@amazon.co.uk>

        Author:   Oleksandr Pylypenko
                  <mailto:opyl@amazon.com>

        Author:   Jeffrey Haas
                  <mailto:jhaas@juniper.net>

        Author:   Aviran Kadosh
                  <mailto:akadosh@cisco.com>

        Author:   Mohamed Boucadair
                  <mailto:mohamed.boucadair@orange.com>";
     description
       "This module defines a data model for packet discard reporting.

        Copyright (c) 2025 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

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        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).

        All revisions of IETF and IANA published modules can be found
        at the YANG Parameters registry
        (https://www.iana.org/assignments/yang-parameters).

        This version of this YANG module is part of RFC XXXX; see the
        RFC itself for full legal notices.";

     revision 2025-03-03 {
       description
         "Initial revision.";
       reference
         "RFC XXXX: Information and Data Models for Packet Discard
                    Reporting";
     }

     /*
      * Features
      */

     feature control-plane-stats {
       description
         "Indicates support of control plane statistics on this
          device.";
     }

     feature interface-stats {
       description
         "Indicates support of interface statistics on this
          device.";
     }

     feature device-stats {
       description
         "Indicates support of global device statistics on this
          device.";
     }

     /*
      * Identities
      */

     identity discard-class {
       description

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         "Base identity to identify the discard calss.";
     }

     identity layer2 {
       base discard-class;
       description
         "Indicates a Layer 2 discard.";
     }

     identity layer3 {
       base discard-class;
       description
         "Indicates a Layer 3 discard.";
     }

     identity internal {
       base discard-class;
       description
         "Indicates an internal discard.";
     }

     identity policy {
       base discard-class;
       description
         "Indicates a discard due to a policy.";
     }

     /*
      * Groupings
      */

     grouping discard-order-policy {
       description
         "Defines the implementation-specific precedence of discard
          classes when multiple discard reasons apply to a single
          packet.

          The list is ordered from highest to lowest precedence.";

       leaf-list discard-order-capability {
         type identityref {
           base discard-class;
         }
         config false;
         description
           "The discard class identity that has this precedence.";
       }
     }

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     /*
      * Main structure definition
      */

     augment "/rt:routing/rt:control-plane-protocols"
           + "/rt:control-plane-protocol" {
       if-feature "control-plane-stats";
       nacm:default-deny-all;
       description
         "Adds control plane discard counters.";
       uses discard-order-policy;
       uses plr-sx:control-plane;
     }
     augment "/if:interfaces-state/if:interface/if:statistics" {
       if-feature "interface-stats";
       nacm:default-deny-all;
       description
         "Adds packet discard reporting to the interface statistics.";
       uses discard-order-policy;
       uses plr-sx:interface;
     }
     augment "/lne:logical-network-elements"
           + "/lne:logical-network-element" {
       if-feature "device-stats";
       nacm:default-deny-all;
       description
         "Adds device level packet counters.";
       uses discard-order-policy;
       uses plr-sx:device;
     }
   }
   <CODE ENDS>

6.  Deployment Considerations Experience

   This section captures practical insights gained from implementing the
   model across multiple vendors' platforms, as guidance for future
   implementers and operators:

   1.  The number and granularity of discard classes defined in the
       Information Model represent a compromise.  It aims to provide
       sufficient detail to enable appropriate automated actions while
       avoiding excessive detail, which may hinder quick problem
       identification.  Additionally, it helps to limit the quantity of
       data produced per interface, constraining the data volume and
       device CPU impacts.  While further granularity is possible, the
       defined schema has generally proven to be sufficient for the task
       of mitigating unintended packet loss.

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   2.  There are many possible ways to define the discard classification
       tree.  For example, an approach is to use a multi-rooted tree,
       rooted in each protocol.  Instead, a better approach is to define
       a tree where protocol discards and causal discard classes are
       accounted for orthogonally.  This decision reduces the number of
       combinations of classes and has proven sufficient for determining
       mitigation actions.

   3.  Platforms often account for the number of packets discarded where
       the TTL has expired (or IPv6 Hop Limit exceeded), and the device
       CPU has returned an ICMP Time Exceeded message [RFC4884].  There
       is typically a policer applied to limit the number of packets
       sent to the device CPU, however, which implicitly limits the rate
       of TTL discards that are processed.  One method to account for
       all packet discards due to TTL expired, even those that are
       dropped by a policer when being forwarded to the CPU, is to use
       accounting of all ingress packets received with TTL=1 as a proxy
       measure.

   4.  Where no route discards are implemented with a default null
       route, separate discard accounting is required for any explicit
       null routes configured in order to differentiate between
       interface/ingress/discards/policy/null-route/packets and
       interface/ingress/discards/errors/no-route/packets.

   5.  It is useful to account separately for transit packets discarded
       by ACLs or policers, and packets discarded by ACLs or policers
       which limit the number of packets to the device control plane.

   6.  It is not possible to identify a configuration error (e.g., when
       intended discards are unintended) with device discard metrics
       alone.  For example, additional context is needed to determine if
       ACL discards are intended or due to a misconfigured ACL (i.e.,
       with configuration validation before deployment or by detecting a
       significant change in ACL discards after a configuration change
       compared to before).

   7.  Aggregate counters need to be able to deal with the possibility
       of discontinuities in the underlying counters.

   8.  While the classification tree is seven layers deep, a minimal
       implementation may only implement the top six layers.

7.  Security Considerations

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7.1.  Information Model

   The Information Model defined in Section 4.3 specifies a YANG module
   using [RFC8791] data extensions.  It defines a set of identities,
   types, and groupings.  These nodes are intended to be reused by other
   YANG modules.  The module by itself does not expose any data nodes
   that are writable, data nodes that contain read-only state, or RPCs.
   As such, there are no additional security issues related to the YANG
   module that need to be considered.

7.2.  Data Model

   This section is modeled after the template described in Section 3.7
   of [I-D.ietf-netmod-rfc8407bis].

   The YANG module specified in Section 5.4 defines a data model that is
   designed to be accessed via YANG-based management protocols, such as
   NETCONF [RFC6241] and RESTCONF [RFC8040].  These YANG-based
   management protocols (1) have to use a secure transport layer (e.g.,
   SSH [RFC4252], TLS [RFC8446], and QUIC [RFC9000]) and (2) have to use
   mutual authentication.

   The Network Configuration Access Control Model (NACM) [RFC8341]
   provides the means to restrict access for particular NETCONF or
   RESTCONF users to a preconfigured subset of all available NETCONF or
   RESTCONF protocol operations and content.

   There are no particularly sensitive writable data nodes.

   Some of the readable data nodes in this YANG module may be considered
   sensitive or vulnerable in some network environments.  It is thus
   important to control read access (e.g., via get, get-config, or
   notification) to these data nodes.  Specifically, the following
   subtrees and data nodes have particular sensitivities/
   vulnerabilities:

   Control-plane, interfaces, and devices:  Access to these data nodes
      would reveal information about the attacks to which an element is
      subject, misconfigurations, etc.

      Also, an attacker who can inject packets can infer the efficiency
      of its attack by monitoring (the increase of) some discard
      counters (e.g., policy) and adjust its attack strategy
      accordingly.

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8.  IANA Considerations

   IANA is requested to register the following URI in the "ns"
   subregistry within the "IETF XML Registry" [RFC3688]:

      URI:  urn:ietf:params:xml:ns:ietf-packet-discard-reporting-sx
      Registrant Contact:  The IESG.
      XML:  N/A; the requested URI is an XML namespace.

      URI:  urn:ietf:params:xml:ns:ietf-packet-discard-reporting
      Registrant Contact:  The IESG.
      XML:  N/A; the requested URI is an XML namespace.

   IANA is requested to register the following YANG module in the "YANG
   Module Names" subregistry [RFC6020] within the "YANG Parameters"
   registry:

     Name:  ietf-packet-discard-reporting-sx
     Namespace:  urn:ietf:params:xml:ns:ietf-packet-discard-reporting-sx
     Prefix:  plr-sx
     Maintained by IANA?  N
     Reference:  RFC XXXX

     Name:  ietf-packet-discard-reporting
     Namespace:  urn:ietf:params:xml:ns:ietf-packet-discard-reporting
     Prefix:  plr
     Maintained by IANA?  N
     Reference:  RFC XXXX

9.  Contributors

   Nadav Chachmon
   Cisco Systems, Inc.
   170 West Tasman Dr.
   San Jose, CA 95134
   United States of America
   Email: nchachmo@cisco.com

10.  Acknowledgments

   The content of this document has benefitted from feedback from JR
   Rivers, Ronan Waide, Chris DeBruin, and Marcos Sanz.

   Thanks to Benoît Claise, Joe Clarke, Tom Petch, Mahesh Jethanandani,
   Paul Aitken, and Randy Bush for the review and comments.

   Thanks to Ladislav Lhotka for the YANGDOCTORS review.

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11.  References

11.1.  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/rfc/rfc2119>.

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              DOI 10.17487/RFC3688, January 2004,
              <https://www.rfc-editor.org/rfc/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/rfc/rfc6020>.

   [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/rfc/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/rfc/rfc8341>.

   [RFC8343]  Bjorklund, M., "A YANG Data Model for Interface
              Management", RFC 8343, DOI 10.17487/RFC8343, March 2018,
              <https://www.rfc-editor.org/rfc/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/rfc/rfc8349>.

   [RFC8530]  Berger, L., Hopps, C., Lindem, A., Bogdanovic, D., and X.
              Liu, "YANG Model for Logical Network Elements", RFC 8530,
              DOI 10.17487/RFC8530, March 2019,
              <https://www.rfc-editor.org/rfc/rfc8530>.

   [RFC8791]  Bierman, A., Björklund, M., and K. Watsen, "YANG Data
              Structure Extensions", RFC 8791, DOI 10.17487/RFC8791,
              June 2020, <https://www.rfc-editor.org/rfc/rfc8791>.

11.2.  Informative References

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   [gMNI]     Marrow, C., "gRPC Network Management Interface, IETF 98,
              March 2017,
              <https://datatracker.ietf.org/meeting/98/materials/slides-
              98-rtgwg-gnmi-intro-draft-openconfig-rtgwg-gnmi-spec-00>",
              n.d..

   [I-D.ietf-netmod-rfc8407bis]
              Bierman, A., Boucadair, M., and Q. Wu, "Guidelines for
              Authors and Reviewers of Documents Containing YANG Data
              Models", Work in Progress, Internet-Draft, draft-ietf-
              netmod-rfc8407bis-28, 5 June 2025,
              <https://datatracker.ietf.org/doc/html/draft-ietf-netmod-
              rfc8407bis-28>.

   [RED93]    Jacobson, V., "Random Early Detection gateways for
              Congestion Avoidance", n.d..

   [RFC1157]  Case, J., Fedor, M., Schoffstall, M., and J. Davin,
              "Simple Network Management Protocol (SNMP)", RFC 1157,
              DOI 10.17487/RFC1157, May 1990,
              <https://www.rfc-editor.org/rfc/rfc1157>.

   [RFC2475]  Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z.,
              and W. Weiss, "An Architecture for Differentiated
              Services", RFC 2475, DOI 10.17487/RFC2475, December 1998,
              <https://www.rfc-editor.org/rfc/rfc2475>.

   [RFC2863]  McCloghrie, K. and F. Kastenholz, "The Interfaces Group
              MIB", RFC 2863, DOI 10.17487/RFC2863, June 2000,
              <https://www.rfc-editor.org/rfc/rfc2863>.

   [RFC3411]  Harrington, D., Presuhn, R., and B. Wijnen, "An
              Architecture for Describing Simple Network Management
              Protocol (SNMP) Management Frameworks", STD 62, RFC 3411,
              DOI 10.17487/RFC3411, December 2002,
              <https://www.rfc-editor.org/rfc/rfc3411>.

   [RFC3444]  Pras, A. and J. Schoenwaelder, "On the Difference between
              Information Models and Data Models", RFC 3444,
              DOI 10.17487/RFC3444, January 2003,
              <https://www.rfc-editor.org/rfc/rfc3444>.

   [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/rfc/rfc4252>.

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   [RFC4884]  Bonica, R., Gan, D., Tappan, D., and C. Pignataro,
              "Extended ICMP to Support Multi-Part Messages", RFC 4884,
              DOI 10.17487/RFC4884, April 2007,
              <https://www.rfc-editor.org/rfc/rfc4884>.

   [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/rfc/rfc6241>.

   [RFC7011]  Claise, B., Ed., Trammell, B., Ed., and P. Aitken,
              "Specification of the IP Flow Information Export (IPFIX)
              Protocol for the Exchange of Flow Information", STD 77,
              RFC 7011, DOI 10.17487/RFC7011, September 2013,
              <https://www.rfc-editor.org/rfc/rfc7011>.

   [RFC7270]  Yourtchenko, A., Aitken, P., and B. Claise, "Cisco-
              Specific Information Elements Reused in IP Flow
              Information Export (IPFIX)", RFC 7270,
              DOI 10.17487/RFC7270, June 2014,
              <https://www.rfc-editor.org/rfc/rfc7270>.

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

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

   [RFC8289]  Nichols, K., Jacobson, V., McGregor, A., Ed., and J.
              Iyengar, Ed., "Controlled Delay Active Queue Management",
              RFC 8289, DOI 10.17487/RFC8289, January 2018,
              <https://www.rfc-editor.org/rfc/rfc8289>.

   [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/rfc/rfc8340>.

   [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/rfc/rfc8446>.

   [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/rfc/rfc9000>.

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Appendix A.  Where Do Packets Get Dropped?

   Understanding where packets are discarded in a network device is
   essential for interpreting discard signals and determining
   appropriate mitigation actions.  Figure 3 depicts an example of where
   and why packets may be discarded in a typical single-ASIC, shared-
   buffered type device.  While actual device architectures vary between
   vendors and platforms, with some using multiple ASICs, distributed
   forwarding, or different buffering architectures, this example
   illustrates the common processing stages where packets may be
   dropped.  The logical model for classifying and reporting discards
   remains consistent regardless of the underlying hardware
   architecture.

   Packets ingress on the left and egress on the right:

                              +-----------+
                              |           |
                              |  Control  |
                              |  Plane    |
                              +---+---^---+
                         from_cpu |   | to_cpu
                                  |   |
         +------------------------v---+------------------------+
         |                                                     |
    +----+----+  +----------+  +---------+  +----------+  +----+----+
    |         |  |          |  |         |  |          |  |         |
Rx--> PHY/MAC +--> Ingress  +--> Buffers +--> Egress   +--> PHY/MAC +-> Tx
    |         |  | Pipeline |  |         |  | Pipeline |  |         |
    +---------+  +----------+  +---------+  +----------+  +---------+

Unintended:
    error/rx/l2  error/l3/rx   no-buffer    error/l3/tx
                 error/l3/no-route
                 error/l3/rx/ttl-expired
                 error/internal
Intended:
                 policy/acl                 policy/acl
                 policy/policer             policy/policer
                 policy/urpf
                 policy/null-route

            Figure 3: Example of where packets get dropped

   See Appendix B for examples of how these discard signals map to root
   causes and mitigation actions.

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Appendix B.  Example Signal-to-mitigation Action Mapping

   The effectiveness of automated mitigation depends on correctly
   mapping discard signals to root causes and appropriate actions.
   Table 1 gives example discard signal-to-mitigation action mappings
   based on the features described in section 3.

   +==============================+===========+==========+========+===========+========+
   |DISCARD-CLASS                 |Discard    |DISCARD-  |DISCARD-|Unintended?|Possible|
   |                              |cause      |RATE      |DURATION|           |actions |
   +==============================+===========+==========+========+===========+========+
   |ingress/discards/errors/l2/rx |Upstream   |>Baseline |O(1min) |     Y     |Take    |
   |                              |device or  |          |        |           |upstream|
   |                              |link error |          |        |           |link or |
   |                              |           |          |        |           |device  |
   |                              |           |          |        |           |out-of- |
   |                              |           |          |        |           |service |
   +------------------------------+-----------+----------+--------+-----------+--------+
   |ingress/discards/errors/l3/rx/|Tracert    |<=Baseline|        |     N     |no      |
   |ttl-expired                   |           |          |        |           |action  |
   +------------------------------+-----------+----------+--------+-----------+--------+
   |ingress/discards/errors/l3/rx/|Convergence|>Baseline | O(1s)  |     Y     |No      |
   |ttl-expired                   |           |          |        |           |action  |
   +------------------------------+-----------+----------+--------+-----------+--------+
   |ingress/discards/errors/l3/rx/|Routing    |>Baseline |O(1min) |     Y     |Roll-   |
   |ttl-expired                   |loop       |          |        |           |back    |
   |                              |           |          |        |           |change  |
   +------------------------------+-----------+----------+--------+-----------+--------+
   |.*/policy/.*                  |Policy     |          |        |     N     |No      |
   |                              |           |          |        |           |action  |
   +------------------------------+-----------+----------+--------+-----------+--------+
   |ingress/discards/errors/l3/no-|Convergence|>Baseline | O(1s)  |     Y     |No      |
   |route                         |           |          |        |           |action  |
   +------------------------------+-----------+----------+--------+-----------+--------+
   |ingress/discards/errors/l3/no-|Config     |>Baseline |O(1min) |     Y     |Roll-   |
   |route                         |error      |          |        |           |back    |
   |                              |           |          |        |           |change  |
   +------------------------------+-----------+----------+--------+-----------+--------+
   |ingress/discards/errors/l3/no-|Invalid    |>Baseline |O(10min)|     N     |Escalate|
   |route                         |destination|          |        |           |to      |
   |                              |           |          |        |           |operator|
   +------------------------------+-----------+----------+--------+-----------+--------+
   |ingress/discards/errors/      |Device     |>Baseline |O(1min) |     Y     |Take    |
   |internal                      |errors     |          |        |           |device  |
   |                              |           |          |        |           |out-of- |
   |                              |           |          |        |           |service |
   +------------------------------+-----------+----------+--------+-----------+--------+
   |egress/discards/no-buffer     |Congestion |<=Baseline|        |     N     |No      |

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   |                              |           |          |        |           |action  |
   +------------------------------+-----------+----------+--------+-----------+--------+
   |egress/discards/no-buffer     |Congestion |>Baseline |O(1min) |     Y     |Bring   |
   |                              |           |          |        |           |capacity|
   |                              |           |          |        |           |back    |
   |                              |           |          |        |           |into    |
   |                              |           |          |        |           |service |
   |                              |           |          |        |           |or move |
   |                              |           |          |        |           |traffic |
   +------------------------------+-----------+----------+--------+-----------+--------+

              Table 1: Example Signal-Cause-Mitigation Mapping

   The 'Baseline' in the 'DISCARD-RATE' column is both DISCARD-CLASS and
   network dependent.

Appendix C.  Full Information Model Tree

   The following YANG tree diagram shows the complete IM structure:

   module: ietf-packet-discard-reporting-sx

     structure packet-discard-reporting:
       +-- control-plane {control-plane-stats}?
       |  +-- traffic* [direction]
       |  |  +-- direction    identityref
       |  |  +-- packets?     yang:counter64
       |  |  +-- bytes?       yang:counter64
       |  +-- discards* [direction]
       |     +-- direction    identityref
       |     +-- packets?     yang:counter64
       |     +-- bytes?       yang:counter64
       |     +-- policy
       |        +-- packets?   yang:counter64
       +-- interface* [name] {interface-stats}?
       |  +-- name        string
       |  +-- traffic* [direction]
       |  |  +-- direction    identityref
       |  |  +-- l2
       |  |  |  +-- frames?   yang:counter64
       |  |  |  +-- bytes?    yang:counter64
       |  |  +-- l3
       |  |  |  +-- address-family-stat* [address-family]
       |  |  |     +-- address-family    identityref
       |  |  |     +-- packets?          yang:counter64
       |  |  |     +-- bytes?            yang:counter64
       |  |  |     +-- unicast
       |  |  |     |  +-- packets?   yang:counter64

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       |  |  |     |  +-- bytes?     yang:counter64
       |  |  |     +-- multicast
       |  |  |        +-- packets?   yang:counter64
       |  |  |        +-- bytes?     yang:counter64
       |  |  +-- qos!
       |  |     +-- class* [id]
       |  |        +-- id         string
       |  |        +-- packets?   yang:counter64
       |  |        +-- bytes?     yang:counter64
       |  +-- discards* [direction]
       |     +-- direction    identityref
       |     +-- l2
       |     |  +-- frames?   yang:counter64
       |     |  +-- bytes?    yang:counter64
       |     +-- l3
       |     |  +-- address-family-stat* [address-family]
       |     |     +-- address-family    identityref
       |     |     +-- packets?          yang:counter64
       |     |     +-- bytes?            yang:counter64
       |     |     +-- unicast
       |     |     |  +-- packets?   yang:counter64
       |     |     |  +-- bytes?     yang:counter64
       |     |     +-- multicast
       |     |        +-- packets?   yang:counter64
       |     |        +-- bytes?     yang:counter64
       |     +-- errors
       |     |  +-- l2
       |     |  |  +-- rx
       |     |  |  |  +-- frames?          yang:counter64
       |     |  |  |  +-- crc-error?       yang:counter64
       |     |  |  |  +-- invalid-mac?     yang:counter64
       |     |  |  |  +-- invalid-vlan?    yang:counter64
       |     |  |  |  +-- invalid-frame?   yang:counter64
       |     |  |  +-- tx
       |     |  |     +-- frames?   yang:counter64
       |     |  +-- l3
       |     |  |  +-- rx
       |     |  |  |  +-- packets?          yang:counter64
       |     |  |  |  +-- checksum-error?   yang:counter64
       |     |  |  |  +-- mtu-exceeded?     yang:counter64
       |     |  |  |  +-- invalid-packet?   yang:counter64
       |     |  |  +-- ttl-expired?     yang:counter64
       |     |  |  +-- no-route?        yang:counter64
       |     |  |  +-- invalid-sid?     yang:counter64
       |     |  |  +-- invalid-label?   yang:counter64
       |     |  |  +-- tx
       |     |  |     +-- packets?   yang:counter64
       |     |  +-- internal

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       |     |     +-- packets?        yang:counter64
       |     |     +-- parity-error?   yang:counter64
       |     +-- policy
       |     |  +-- l2
       |     |  |  +-- frames?   yang:counter64
       |     |  |  +-- acl?      yang:counter64
       |     |  +-- l3
       |     |     +-- packets?      yang:counter64
       |     |     +-- acl?          yang:counter64
       |     |     +-- policer
       |     |     |  +-- packets?   yang:counter64
       |     |     |  +-- bytes?     yang:counter64
       |     |     |  +-- classes!
       |     |     |     +-- class* [id]
       |     |     |        +-- id         string
       |     |     |        +-- packets?   yang:counter64
       |     |     |        +-- bytes?     yang:counter64
       |     |     +-- null-route?   yang:counter64
       |     |     +-- rpf?          yang:counter64
       |     |     +-- ddos?         yang:counter64
       |     +-- no-buffer
       |        +-- qos!
       |           +-- class* [id]
       |              +-- id         string
       |              +-- packets?   yang:counter64
       |              +-- bytes?     yang:counter64
       +-- flow* [direction] {flow-reporting}?
       |  +-- direction    identityref
       |  +-- traffic
       |  |  +-- l2
       |  |  |  +-- frames?   yang:counter64
       |  |  |  +-- bytes?    yang:counter64
       |  |  +-- l3
       |  |  |  +-- address-family-stat* [address-family]
       |  |  |     +-- address-family    identityref
       |  |  |     +-- packets?          yang:counter64
       |  |  |     +-- bytes?            yang:counter64
       |  |  |     +-- unicast
       |  |  |     |  +-- packets?   yang:counter64
       |  |  |     |  +-- bytes?     yang:counter64
       |  |  |     +-- multicast
       |  |  |        +-- packets?   yang:counter64
       |  |  |        +-- bytes?     yang:counter64
       |  |  +-- qos!
       |  |     +-- class* [id]
       |  |        +-- id         string
       |  |        +-- packets?   yang:counter64
       |  |        +-- bytes?     yang:counter64

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       |  +-- discards
       |     +-- l2
       |     |  +-- frames?   yang:counter64
       |     |  +-- bytes?    yang:counter64
       |     +-- l3
       |     |  +-- address-family-stat* [address-family]
       |     |     +-- address-family    identityref
       |     |     +-- packets?          yang:counter64
       |     |     +-- bytes?            yang:counter64
       |     |     +-- unicast
       |     |     |  +-- packets?   yang:counter64
       |     |     |  +-- bytes?     yang:counter64
       |     |     +-- multicast
       |     |        +-- packets?   yang:counter64
       |     |        +-- bytes?     yang:counter64
       |     +-- errors
       |     |  +-- l2
       |     |  |  +-- rx
       |     |  |  |  +-- frames?          yang:counter64
       |     |  |  |  +-- crc-error?       yang:counter64
       |     |  |  |  +-- invalid-mac?     yang:counter64
       |     |  |  |  +-- invalid-vlan?    yang:counter64
       |     |  |  |  +-- invalid-frame?   yang:counter64
       |     |  |  +-- tx
       |     |  |     +-- frames?   yang:counter64
       |     |  +-- l3
       |     |  |  +-- rx
       |     |  |  |  +-- packets?          yang:counter64
       |     |  |  |  +-- checksum-error?   yang:counter64
       |     |  |  |  +-- mtu-exceeded?     yang:counter64
       |     |  |  |  +-- invalid-packet?   yang:counter64
       |     |  |  +-- ttl-expired?     yang:counter64
       |     |  |  +-- no-route?        yang:counter64
       |     |  |  +-- invalid-sid?     yang:counter64
       |     |  |  +-- invalid-label?   yang:counter64
       |     |  |  +-- tx
       |     |  |     +-- packets?   yang:counter64
       |     |  +-- internal
       |     |     +-- packets?        yang:counter64
       |     |     +-- parity-error?   yang:counter64
       |     +-- policy
       |     |  +-- l2
       |     |  |  +-- frames?   yang:counter64
       |     |  |  +-- acl?      yang:counter64
       |     |  +-- l3
       |     |     +-- packets?      yang:counter64
       |     |     +-- acl?          yang:counter64
       |     |     +-- policer

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       |     |     |  +-- packets?   yang:counter64
       |     |     |  +-- bytes?     yang:counter64
       |     |     |  +-- classes!
       |     |     |     +-- class* [id]
       |     |     |        +-- id         string
       |     |     |        +-- packets?   yang:counter64
       |     |     |        +-- bytes?     yang:counter64
       |     |     +-- null-route?   yang:counter64
       |     |     +-- rpf?          yang:counter64
       |     |     +-- ddos?         yang:counter64
       |     +-- no-buffer
       |        +-- qos!
       |           +-- class* [id]
       |              +-- id         string
       |              +-- packets?   yang:counter64
       |              +-- bytes?     yang:counter64
       +-- device {device-stats}?
          +-- traffic
          |  +-- l2
          |  |  +-- frames?   yang:counter64
          |  |  +-- bytes?    yang:counter64
          |  +-- l3
          |  |  +-- address-family-stat* [address-family]
          |  |     +-- address-family    identityref
          |  |     +-- packets?          yang:counter64
          |  |     +-- bytes?            yang:counter64
          |  |     +-- unicast
          |  |     |  +-- packets?   yang:counter64
          |  |     |  +-- bytes?     yang:counter64
          |  |     +-- multicast
          |  |        +-- packets?   yang:counter64
          |  |        +-- bytes?     yang:counter64
          |  +-- qos!
          |     +-- class* [id]
          |        +-- id         string
          |        +-- packets?   yang:counter64
          |        +-- bytes?     yang:counter64
          +-- discards
             +-- l2
             |  +-- frames?   yang:counter64
             |  +-- bytes?    yang:counter64
             +-- l3
             |  +-- address-family-stat* [address-family]
             |     +-- address-family    identityref
             |     +-- packets?          yang:counter64
             |     +-- bytes?            yang:counter64
             |     +-- unicast
             |     |  +-- packets?   yang:counter64

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             |     |  +-- bytes?     yang:counter64
             |     +-- multicast
             |        +-- packets?   yang:counter64
             |        +-- bytes?     yang:counter64
             +-- errors
             |  +-- l2
             |  |  +-- rx
             |  |  |  +-- frames?          yang:counter64
             |  |  |  +-- crc-error?       yang:counter64
             |  |  |  +-- invalid-mac?     yang:counter64
             |  |  |  +-- invalid-vlan?    yang:counter64
             |  |  |  +-- invalid-frame?   yang:counter64
             |  |  +-- tx
             |  |     +-- frames?   yang:counter64
             |  +-- l3
             |  |  +-- rx
             |  |  |  +-- packets?          yang:counter64
             |  |  |  +-- checksum-error?   yang:counter64
             |  |  |  +-- mtu-exceeded?     yang:counter64
             |  |  |  +-- invalid-packet?   yang:counter64
             |  |  +-- ttl-expired?     yang:counter64
             |  |  +-- no-route?        yang:counter64
             |  |  +-- invalid-sid?     yang:counter64
             |  |  +-- invalid-label?   yang:counter64
             |  |  +-- tx
             |  |     +-- packets?   yang:counter64
             |  +-- internal
             |     +-- packets?        yang:counter64
             |     +-- parity-error?   yang:counter64
             +-- policy
             |  +-- l2
             |  |  +-- frames?   yang:counter64
             |  |  +-- acl?      yang:counter64
             |  +-- l3
             |     +-- packets?      yang:counter64
             |     +-- acl?          yang:counter64
             |     +-- policer
             |     |  +-- packets?   yang:counter64
             |     |  +-- bytes?     yang:counter64
             |     |  +-- classes!
             |     |     +-- class* [id]
             |     |        +-- id         string
             |     |        +-- packets?   yang:counter64
             |     |        +-- bytes?     yang:counter64
             |     +-- null-route?   yang:counter64
             |     +-- rpf?          yang:counter64
             |     +-- ddos?         yang:counter64
             +-- no-buffer

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                +-- qos!
                   +-- class* [id]
                      +-- id         string
                      +-- packets?   yang:counter64
                      +-- bytes?     yang:counter64

Appendix D.  Full Data Model Tree

   The following YANG tree diagram shows the complete data module
   structure:

   module: ietf-packet-discard-reporting

     augment /rt:routing/rt:control-plane-protocols
               /rt:control-plane-protocol:
       +--ro discard-order-capability*   identityref
       |       {control-plane-stats}?
       +--rw traffic* [direction] {control-plane-stats}?
       |  +--rw direction    identityref
       |  +--rw packets?     yang:counter64
       |  +--rw bytes?       yang:counter64
       +--rw discards* [direction] {control-plane-stats}?
          +--rw direction    identityref
          +--rw packets?     yang:counter64
          +--rw bytes?       yang:counter64
          +--rw policy
             +--rw packets?   yang:counter64
     augment /if:interfaces-state/if:interface/if:statistics:
       +--ro discard-order-capability*   identityref {interface-stats}?
       +--ro traffic* [direction] {interface-stats}?
       |  +--ro direction    identityref
       |  +--ro l2
       |  |  +--ro frames?   yang:counter64
       |  |  +--ro bytes?    yang:counter64
       |  +--ro l3
       |  |  +--ro address-family-stat* [address-family]
       |  |     +--ro address-family    identityref
       |  |     +--ro packets?          yang:counter64
       |  |     +--ro bytes?            yang:counter64
       |  |     +--ro unicast
       |  |     |  +--ro packets?   yang:counter64
       |  |     |  +--ro bytes?     yang:counter64
       |  |     +--ro multicast
       |  |        +--ro packets?   yang:counter64
       |  |        +--ro bytes?     yang:counter64
       |  +--ro qos!
       |     +--ro class* [id]
       |        +--ro id         string

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       |        +--ro packets?   yang:counter64
       |        +--ro bytes?     yang:counter64
       +--ro discards* [direction] {interface-stats}?
          +--ro direction    identityref
          +--ro l2
          |  +--ro frames?   yang:counter64
          |  +--ro bytes?    yang:counter64
          +--ro l3
          |  +--ro address-family-stat* [address-family]
          |     +--ro address-family    identityref
          |     +--ro packets?          yang:counter64
          |     +--ro bytes?            yang:counter64
          |     +--ro unicast
          |     |  +--ro packets?   yang:counter64
          |     |  +--ro bytes?     yang:counter64
          |     +--ro multicast
          |        +--ro packets?   yang:counter64
          |        +--ro bytes?     yang:counter64
          +--ro errors
          |  +--ro l2
          |  |  +--ro rx
          |  |  |  +--ro frames?          yang:counter64
          |  |  |  +--ro crc-error?       yang:counter64
          |  |  |  +--ro invalid-mac?     yang:counter64
          |  |  |  +--ro invalid-vlan?    yang:counter64
          |  |  |  +--ro invalid-frame?   yang:counter64
          |  |  +--ro tx
          |  |     +--ro frames?   yang:counter64
          |  +--ro l3
          |  |  +--ro rx
          |  |  |  +--ro packets?          yang:counter64
          |  |  |  +--ro checksum-error?   yang:counter64
          |  |  |  +--ro mtu-exceeded?     yang:counter64
          |  |  |  +--ro invalid-packet?   yang:counter64
          |  |  +--ro ttl-expired?     yang:counter64
          |  |  +--ro no-route?        yang:counter64
          |  |  +--ro invalid-sid?     yang:counter64
          |  |  +--ro invalid-label?   yang:counter64
          |  |  +--ro tx
          |  |     +--ro packets?   yang:counter64
          |  +--ro internal
          |     +--ro packets?        yang:counter64
          |     +--ro parity-error?   yang:counter64
          +--ro policy
          |  +--ro l2
          |  |  +--ro frames?   yang:counter64
          |  |  +--ro acl?      yang:counter64
          |  +--ro l3

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          |     +--ro packets?      yang:counter64
          |     +--ro acl?          yang:counter64
          |     +--ro policer
          |     |  +--ro packets?   yang:counter64
          |     |  +--ro bytes?     yang:counter64
          |     |  +--ro classes!
          |     |     +--ro class* [id]
          |     |        +--ro id         string
          |     |        +--ro packets?   yang:counter64
          |     |        +--ro bytes?     yang:counter64
          |     +--ro null-route?   yang:counter64
          |     +--ro rpf?          yang:counter64
          |     +--ro ddos?         yang:counter64
          +--ro no-buffer
             +--ro qos!
                +--ro class* [id]
                   +--ro id         string
                   +--ro packets?   yang:counter64
                   +--ro bytes?     yang:counter64
     augment /lne:logical-network-elements/lne:logical-network-element:
       +--ro discard-order-capability*   identityref {device-stats}?
       +--rw traffic {device-stats}?
       |  +--rw l2
       |  |  +--rw frames?   yang:counter64
       |  |  +--rw bytes?    yang:counter64
       |  +--rw l3
       |  |  +--rw address-family-stat* [address-family]
       |  |     +--rw address-family    identityref
       |  |     +--rw packets?          yang:counter64
       |  |     +--rw bytes?            yang:counter64
       |  |     +--rw unicast
       |  |     |  +--rw packets?   yang:counter64
       |  |     |  +--rw bytes?     yang:counter64
       |  |     +--rw multicast
       |  |        +--rw packets?   yang:counter64
       |  |        +--rw bytes?     yang:counter64
       |  +--rw qos!
       |     +--rw class* [id]
       |        +--rw id         string
       |        +--rw packets?   yang:counter64
       |        +--rw bytes?     yang:counter64
       +--rw discards {device-stats}?
          +--rw l2
          |  +--rw frames?   yang:counter64
          |  +--rw bytes?    yang:counter64
          +--rw l3
          |  +--rw address-family-stat* [address-family]
          |     +--rw address-family    identityref

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          |     +--rw packets?          yang:counter64
          |     +--rw bytes?            yang:counter64
          |     +--rw unicast
          |     |  +--rw packets?   yang:counter64
          |     |  +--rw bytes?     yang:counter64
          |     +--rw multicast
          |        +--rw packets?   yang:counter64
          |        +--rw bytes?     yang:counter64
          +--rw errors
          |  +--rw l2
          |  |  +--rw rx
          |  |  |  +--rw frames?          yang:counter64
          |  |  |  +--rw crc-error?       yang:counter64
          |  |  |  +--rw invalid-mac?     yang:counter64
          |  |  |  +--rw invalid-vlan?    yang:counter64
          |  |  |  +--rw invalid-frame?   yang:counter64
          |  |  +--rw tx
          |  |     +--rw frames?   yang:counter64
          |  +--rw l3
          |  |  +--rw rx
          |  |  |  +--rw packets?          yang:counter64
          |  |  |  +--rw checksum-error?   yang:counter64
          |  |  |  +--rw mtu-exceeded?     yang:counter64
          |  |  |  +--rw invalid-packet?   yang:counter64
          |  |  +--rw ttl-expired?     yang:counter64
          |  |  +--rw no-route?        yang:counter64
          |  |  +--rw invalid-sid?     yang:counter64
          |  |  +--rw invalid-label?   yang:counter64
          |  |  +--rw tx
          |  |     +--rw packets?   yang:counter64
          |  +--rw internal
          |     +--rw packets?        yang:counter64
          |     +--rw parity-error?   yang:counter64
          +--rw policy
          |  +--rw l2
          |  |  +--rw frames?   yang:counter64
          |  |  +--rw acl?      yang:counter64
          |  +--rw l3
          |     +--rw packets?      yang:counter64
          |     +--rw acl?          yang:counter64
          |     +--rw policer
          |     |  +--rw packets?   yang:counter64
          |     |  +--rw bytes?     yang:counter64
          |     |  +--rw classes!
          |     |     +--rw class* [id]
          |     |        +--rw id         string
          |     |        +--rw packets?   yang:counter64
          |     |        +--rw bytes?     yang:counter64

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          |     +--rw null-route?   yang:counter64
          |     +--rw rpf?          yang:counter64
          |     +--rw ddos?         yang:counter64
          +--rw no-buffer
             +--rw qos!
                +--rw class* [id]
                   +--rw id         string
                   +--rw packets?   yang:counter64
                   +--rw bytes?     yang:counter64

Authors' Addresses

   John Evans
   Amazon
   1 Principal Place, Worship Street
   London
   EC2A 2FA
   United Kingdom
   Email: jevanamz@amazon.co.uk

   Oleksandr Pylypenko
   Amazon
   410 Terry Ave N
   Seattle, WA 98109
   United States of America
   Email: opyl@amazon.com

   Jeffrey Haas
   Juniper Networks
   1133 Innovation Way
   Sunnyvale, CA 94089
   United States of America
   Email: jhaas@juniper.net

   Aviran Kadosh
   Cisco Systems, Inc.
   170 West Tasman Dr.
   San Jose, CA 95134
   United States of America
   Email: akadosh@cisco.com

   Mohamed Boucadair
   Orange
   France

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   Email: mohamed.boucadair@orange.com

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