Internet-Draft YANG Models for QoS July 2022
Choudhary, et al. Expires 8 January 2023 [Page]
Workgroup:
Network Working Group
Internet-Draft:
draft-ietf-rtgwg-qos-model-08
Published:
Intended Status:
Standards Track
Expires:
Authors:
A.C. Choudhary
Aviatrix Systems
M. Jethanandani
Kloud Services
E. Aries
Juniper Networks
I. Chen
The MITRE Corporation

YANG Models for Quality of Service (QoS)

Abstract

This document describes a YANG model for configuration of Quality of Service (QoS) configuration in network devices. This document doesn't describe QoS statistics counters.

Status of This Memo

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

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

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

This Internet-Draft will expire on 8 January 2023.

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Table of Contents

1. Introduction

This document defines a base YANG [RFC6020] [RFC7950] model for Quality of Service (QoS) configuration parameters. QoS base modules define the basic building blocks to define a classifier, policy, action and target. The base models are augmented to include packet match fields and action parameters to define the Diffrentiated Services (DiffServ) module. Queues and schedulers are stitched as part of diffserv policy model. Separate models have been defined for creating Queue policy and Scheduling policy. The DiffServ model is based on DiffServ architecture, and various references have been made to available standard architecture documents.

DiffServ is a preferred approach for network service providers to offer services to different customers based on their network Quality-of-Service (QoS) objectives. The traffic streams are differentiated based on DiffServ Code Points (DSCP) carried in the IP header of each packet. The DSCP markings are applied by upstream node or by the edge router on entry to the DiffServ network.

The YANG modules in this document conform to the Network Management Datastore Architecture (NMDA) [RFC8342].

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

1.1. Note to RFC Editor

Editorial Note: (To be removed by RFC Editor)

This draft contains several placeholder values that need to be replaced with finalized values at the time of publication. Please apply the following replacements:

  • "XXXX" --> the assigned RFC value for this draft both in this draft and in the yang modules under the revision statement.
  • The "revision" date in model, in the format XXXX-XX-XX, needs to be updated with the date the draft gets approved.

1.2. 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.

1.3. Definitions and Acronyms

This document uses definitions and acronyms defined in Definitions of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers [RFC2474], An Architecture for Differentiated Services [RFC2475], and other documents. Here are some of them.

  • Classifier: an entity which selects packets based on the content of packet headers according to defined rules.
  • DiffServ: Differentiated Services enhancements to the Internet protocol are intended to enable scalable service discrimination in the Internet without the need for per-flow state and signaling at every hop. A variety of services may be built from a small, well-defined set of building blocks which are deployed in network nodes.
  • DSCP: Differentiated Services Code Point
  • Marking: the process of setting the DS codepoint in a packet based on defined rules; pre-marking, re-marking.
  • Metering: the process of measuring the temporal properties (e.g., rate) of a traffic stream selected by a classifier. The instantaneous state of this process may be used to affect the operation of a marker, shaper, or dropper, and/or may be used for accounting and measurement purposes.
  • Policing: the process of discarding packets (by a dropper) within a traffic stream in accordance with the state of a corresponding meter enforcing a traffic profile.
  • RED: Random Early Detection
  • Shaping: the process of delaying packets within a traffic stream to cause it to conform to some defined traffic profile.
  • WRED: Weighted Random Early Detection

2. QoS Model Design

A classifier consists of packets which may be grouped when a logical set of rules are applied on different packet header fields. The grouping may be based on different values or range of values of same packet header field, presence or absence of some values or range of values of a packet field or a combination thereof. The QoS classifier is defined in the ietf-qos-classifier module.

A classifier entry contains one or more packet conditioning functions. A packet conditioning function is typically based on direction of traffic and may drop, mark or delay network packets. A set of classifier entries with corresponding conditioning functions when arranged in order of priority represents a QoS policy. A QoS policy may contain one or more classifier entries. These are defined in ietf-traffic-policy module.

Actions are configured in line with respect to the policy module. These include marking, dropping or shaping. Actions are defined in the ietf-qos-action module.

A meter qualifies if the traffic arrival rate is based on agreed upon rate and variability. A meter is modeled based on commonly used alogrithms in industry, Single Rate Tri Color Marking (srTCM) [RFC2697] meter, Two Rate Tri Color Marking (trTCM) [RFC2698] meter, and Single Rate Two Color Marking meter. Different vendors can extend it with other types of meters as well.

QoS operational model include QoS policy applied to an interface in each direction of traffic. For each QoS policy applied to an interface the model further includes counters for associated Classifiers, Meters and Queues in a particular direction. To modularize and for reusability, grouping have been defined for various counters of classifier, Meters and Queues. The target is assumed to be interface but the groupings can be used for any other target type where QoS policy is applied.

3. DiffServ Model Design

DiffServ architecture [RFC3289] and [RFC2475] describe the architecture as a simple model where traffic entering a network is classified and possibly conditioned at the boundary of the network and assigned a different Behavior Aggregate (BA). Each BA is identified by a specific value of DSCP, and is used to select a Per Hop Behavior (PHB).

The packet classification policy identifies the subset of traffic which may receive a DiffServ by being conditioned or mapped. Packet classifiers select packets within a stream based on the content of some portion of the packet header. There are two types of classifiers, the BA classifier, and the Multi-Field (MF) classifier which selects packets based on a value which is combination of one or more header fields. In the ietf-diffserv module, this is realized by augmenting the QoS classification module.

Traffic conditioning includes metering, shaping and/or marking. A meter is used to measure the traffic against a given traffic profile. The traffic profile specifies the temporal property of the traffic. A packet that arrives is first determined to be in or out of the profile, which will result in the action of marked, dropped or shaped. This is realized in vendor specific modules based on the parameters defined in action module. The metering parameters are augmented to the QoS policy module when metering is defined inline, and to the metering template when metering profile is referred in policy module.

4. Modules Tree Structure

This document defines seven YANG modules - four QoS base modules, a scheduler policy module, a queuing policy module and one DiffServ module.

ietf-qos-classifier consists of classifier entries identified by a classifier entry name. Each entry MAY contain a list of filter entries. When no filter entry is present in a classifier entry, it matches all traffic.

An ietf-traffic-policy module contains list of policy objects identified by a policy name and policy type which MUST be provided. With different values of policy types, each vendor MAY define their own construct of policy for different QoS functionalities. Each vendor MAY augment classifier entry in a policy definition with a set of actions.

module: ietf-traffic-policy
  +--rw classifiers {classifier-template-feature}?
  |  +--rw classifier* [name]
  |     +--rw name                string
  |     +--rw description?        string
  |     +--rw filter-operation?   identityref
  |     +--rw filter* [type logical-not]
  |           ...
  +--rw policies
     +--rw policy* [name type]
        +--rw name           string
        +--rw type           identityref
        +--rw description?   string
        +--rw classifier* [name]
              ...

  augment /if:interfaces/if:interface:
    +--rw qos-target-policy* [direction type]
       +--rw direction    identityref
       +--rw type         identityref
       +--rw name         string
Figure 1: ietf-traffic-policy tree diagram

ietf-qos-action module contains grouping of set of QoS actions. These include metering, marking, dropping and shaping. Marking sets DiffServ codepoint value in the classified packet. Color-aware and Color-blind meters are augmented by vendor specific modules based on the parameters defined in action module.

module: ietf-qos-action
  +--rw meters
     +--rw meter* [name]
        +--rw name                              string
        +--rw (meter-type)?
              ...
Figure 2: ietf-qos-actions tree diagram

ietf-qos-target module contains reference of qos-policy and augments ietf-interfaces [RFC8343] module. A single policy of a particular policy-type can be applied on an interface in each direction of traffic. Policy-type is of type identity and is populated in a vendor specific manner. This way it provides greater flexibility for each vendor to define different policy types each with its own capabilities and restrictions.

Classifier, metering and queuing counters are associated with a target.

Diffserv module augments QoS classifier module. Many of the YANG types defined in [RFC6991] are represented as leafs in the classifier module.

Metering and marking actions are realized by augmenting the QoS policy-module. Any queuing, AQM and scheduling actions are part of vendor specific augmentation. Statistics are realized by augmenting the QoS target module.

Classifier statistics consist of list of classifier entries identified by a classifier entry name. Classifier counters include matched packets and bytes, and average rate of traffic matching a particular classifier.

Metering statistics consist of meters identified by an identifier. Metering counters include conform, exceed, violate, drop packets, and bytes.

Queuing counters include instantaneous, peak, average queue length, as well as output conform, exceed, tail drop packets and bytes.

Named statistics is defined as statistics which is tagged by a name. This could be aggregated or non-aggregated. Aggregated named statistics is defined as counters which are aggregated across classifier entries in a policy applied to an interface in a particular direction. Non-aggregated named statistics are counters of classifier, metering or queuing which have the same tag name but maintained separately.

module: ietf-diffserv

  augment /policy:classifiers/policy:classifier/policy:filter:
    +--rw (filter-param)?
       +--:(dscp)
       |  +--rw dscp* [dscp-min dscp-max]
       |        ...
       +--:(source-ipv4-prefix)
       |  +--rw source-ipv4-prefix* [source-ipv4-prefix]
       |        ...
       +--:(destination-ipv4-prefix)
       |  +--rw destination-ipv4-prefix* [destination-ipv4-prefix]
       |        ...
       +--:(source-ipv6-prefix)
       |  +--rw source-ipv6-prefix* [source-ipv6-prefix]
       |        ...
       +--:(destination-ipv6-prefix)
       |  +--rw destination-ipv6-prefix* [destination-ipv6-prefix]
       |        ...
       +--:(source-port)
       |  +--rw source-port* [source-port-min source-port-max]
       |        ...
       +--:(destination-port)
       |  +--rw destination-port*
       |          [destination-port-min destination-port-max]
       |        ...
       +--:(protocol)
       |  +--rw protocol* [protocol-min protocol-max]
       |        ...
       +--:(traffic-group)
          +--rw traffic-group
                ...
  augment /policy:policies/policy:policy/policy:classifier
            /policy:filter:
    +--rw (filter-params)?
       +--:(dscp)
       |  +--rw dscp* [dscp-min dscp-max]
       |        ...
       +--:(source-ipv4-prefix)
       |  +--rw source-ipv4-prefix* [source-ipv4-prefix]
       |        ...
       +--:(destination-ipv4-prefix)
       |  +--rw destination-ipv4-prefix* [destination-ipv4-prefix]
       |        ...
       +--:(source-ipv6-prefix)
       |  +--rw source-ipv6-prefix* [source-ipv6-prefix]
       |        ...
       +--:(destination-ipv6-prefix)
       |  +--rw destination-ipv6-prefix* [destination-ipv6-prefix]
       |        ...
       +--:(source-port)
       |  +--rw source-port* [source-port-min source-port-max]
       |        ...
       +--:(destination-port)
       |  +--rw destination-port*
       |          [destination-port-min destination-port-max]
       |        ...
       +--:(protocol)
       |  +--rw protocol* [protocol-min protocol-max]
       |        ...
       +--:(traffic-group)
          +--rw traffic-group
                ...
  augment /policy:policies/policy:policy/policy:classifier
            /policy:action/policy:action-params:
    +--:(dscp-marking)
    |  +--rw dscp
    |     +--rw dscp?   inet:dscp
    +--:(meter-inline)
    |  +--rw (meter-type)?
    |     +--:(one-rate-two-color-meter-type)
    |     |     ...
    |     +--:(one-rate-tri-color-meter-type)
    |     |     ...
    |     +--:(two-rate-tri-color-meter-type)
    |           ...
    +--:(meter-reference)
    |  +--rw meter
    |     +--rw name    string
    |     +--rw type    identityref
    +--:(traffic-group-marking)
    |  +--rw traffic-group
    |     +--rw traffic-group?   string
    +--:(child-policy) {action:child-policy-feature}?
    |  +--rw child-policy {child-policy-feature}?
    |     +--rw policy-name?   string
    +--:(count) {action:count-feature}?
    |  +--rw count {count-feature}?
    |     +--rw count-action?   empty
    +--:(named-count) {action:named-counter-feature}?
    |  +--rw named-counter {named-counter-feature}?
    |     +--rw count-name-action?   string
    +--:(queue-inline)
    |  +--rw queue
    |     +--rw priority
    |     |     ...
    |     +--rw min-rate
    |     |     ...
    |     +--rw max-rate
    |     |     ...
    |     +--rw algorithmic-drop
    |           ...
    +--:(scheduler-inline)
       +--rw scheduler
          +--rw min-rate
          |     ...
          +--rw max-rate
                ...
Figure 3: ietf-diffserv tree diagram 
module: ietf-queue-policy
  +--rw queue
     +--rw name?    string
     +--rw queue
        +--rw priority
        |     ...
        +--rw min-rate
        |     ...
        +--rw max-rate
        |     ...
        +--rw algorithmic-drop
              ...

  augment /policy:policies/policy:policy/policy:classifier
            /policy:filter:
    +--rw (filter-params)?
       +--:(traffic-group-name)
          +--rw traffic-group
                ...
  augment /policy:policies/policy:policy/policy:classifier
            /policy:action/policy:action-params:
    +--:(queue-template-name)
    |  +--rw queue-reference
    |     +--rw queue-name    string
    +--:(queue-inline)
       +--rw queue
          +--rw priority
          |     ...
          +--rw min-rate
          |     ...
          +--rw max-rate
          |     ...
          +--rw algorithmic-drop
                ...
Figure 4: ietf-queue-policy tree diagram 
module: ietf-scheduler-policy

  augment /policy:policies/policy:policy/policy:classifier
            /policy:filter:
    +--rw (filter-params)?
       +--:(filter-match-all)
          +--rw match-all-cfg
                ...
  augment /policy:policies/policy:policy/policy:classifier
            /policy:action/policy:action-params:
    +--:(scheduler)
    |  +--rw scheduler
    |     +--rw min-rate
    |     |     ...
    |     +--rw max-rate
    |           ...
    +--:(queue-policy-name)
       +--rw queue-policy-name
          +--rw queue-policy    string
Figure 5: ietf-scheduler-policy tree diagram 
module: ietf-qos-oper

  augment /if:interfaces/if:interface:
    +--ro qos-interface-statistics
       +--ro stats-per-direction* []
          +--ro direction?               identityref
          +--ro policy-name?             string
          +--ro classifier-statistics* []
          |     ...
          +--ro named-statistics* []
          |     ...
          +--ro metering-statistics* []
          |     ...
          +--ro queueing-statistics* []
                ...
Figure 6: ietf-qos-oper tree diagram

5. Modules

Modules defined in this draft import definitions from "Common YANG Data Types" [RFC6991] and "A YANG Data Model for Interface Management" [RFC8343].

5.1. ietf-traffic-policy 

<CODE BEGINS> file "ietf-traffic-policy@2022-07-08.yang"

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

  import ietf-interfaces {
    prefix if;
  }
  import ietf-qos-action {
    prefix action;
  }

  organization
    "IETF Routing Area Working Group";

  contact
    "WG Web:   <https://datatracker.ietf.org/wg/rtgwg/>
     WG List:  <mailto:rtgwg@ietf.org>

     Editor:   Aseem Choudhary
               <mailto:achoudhary@aviatrix.com>
     Editor:   Mahesh Jethanandani
               <mailto:mjethanandani@gmail.com>";

  description
    "This module contains a collection of YANG definitions for
     configuring qos specification implementations.

     Copyright (c) 2021 IETF Trust and the persons identified as
     authors of the code.  All rights reserved.

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

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

  revision 2022-07-08 {
    description
      "Initial version";
    reference
      "RFC XXXX: YANG Models for Quality of Service (QoS).";
  }

  feature policy-inline-classifier-config {
    description
      " This feature allows classifier configuration
        directly under policy.";
  }
  feature classifier-template-feature {
    description
       " This feature allows classifier as template configuration
         in a policy.";
  }
  identity policy-type {
    description
      "This base identity type defines policy-types";
  }
  identity diffserv {
    base policy-type;
    description
      "This defines ip policy-type";
  }
  identity ipv4-diffserv {
    base policy-type;
    description
      "This defines ipv4 policy-type";
  }
  identity ipv6-diffserv {
    base policy-type;
    description
      "This defines ipv6 policy-type";
  }

  identity filter-type {
    description
      "This is identity of base filter-type";
  }
  identity dscp {
    base filter-type;
    description
      "Differentiated services code point filter-type";
  }
  identity source-ipv4-prefix {
    base filter-type;
    description
      "source ipv4 prefix filter-type";
  }
  identity destination-ipv4-prefix {
    base filter-type;
    description
      "destination ipv4 prefix filter-type";
  }
  identity source-ipv6-prefix {
    base filter-type;
    description
      "source ipv6 prefix filter-type";
  }
  identity destination-ipv6-prefix {
    base filter-type;
    description
      "destination ipv6 prefix filter-type";
  }
  identity source-port {
    base filter-type;
    description
      "source port filter-type";
  }
  identity destination-port {
    base filter-type;
    description
      "destination port filter-type";
  }
  identity protocol {
    base filter-type;
    description
      "protocol type filter-type";
  }
  identity traffic-group-name {
    base filter-type;
    description
      "traffic-group filter type";
  }

  identity match-filter-operation {
    description
      "filter match logical operation type";
  }
  identity match-all-filter {
    base match-filter-operation;
    description
      "Classifier entry filter logical AND operation";
  }
  identity match-any-filter {
    base match-filter-operation;
    description
      "Classifier entry filter logical OR operation";
  }
  identity direction {
    description
      "This is identity of traffic direction";
  }
  identity inbound {
    base direction;
    description
      "Direction of traffic coming into the network entry";
  }
  identity outbound {
    base direction;
    description
      "Direction of traffic going out of the network entry";
  }
  grouping filters {
    description
      "Filters types in a Classifier entry";
    leaf type {
      type identityref {
        base filter-type;
      }
      description
        "This leaf defines type of the filter";
    }
    leaf logical-not {
      type boolean;
      description
        "This is logical-not operator for a filter. When true, it
         indicates filter looks for absence of a pattern defined
         by the filter.";
    }
  }
  grouping generic-classifier-attr {
    description
      "
       Classifier generic attributes like name,
       description, operation type
      ";
    leaf name {
      type string;
      description
        "classifier entry name";
    }
    leaf description {
      type string;
      description
        "classifier entry description statement";
    }
    leaf filter-operation {
      type identityref {
        base match-filter-operation;
      }
      default "match-all-filter";
      description
        "Filters are applicable as match-any or match-all filters";
    }
  }
  grouping inline-attr {
    description
      "attributes of inline classifier in a policy";
    leaf inline {
      type boolean;
      default "false";
      description
        "Indication of inline classifier entry";
    }
    leaf filter-operation {
      type identityref {
        base match-filter-operation;
      }
      default "match-all-filter";
      description
        "Filters are applicable as match-any or match-all filters";
    }
    list filter{
      if-feature policy-inline-classifier-config;
      must " ../inline = 'true' " {
        description
          "For inline filter configuration, inline attribute" +
          "must be true";
      }
      key "type logical-not";
      uses filters;
      description
        "Filters configured inline in a policy";
    }
  }
  grouping generic-policy-attr {
    description
      "Policy Attributes";
    leaf name {
      type string;
      description
        "policy name";
    }
    leaf type {
      type identityref {
        base policy-type;
      }
      description
        "policy type";
    }
    leaf description {
      type string;
      description
        "policy description";
    }
  }
  identity action-type {
    description
      "This base identity type defines action-types";
  }
  identity dscp-marking {
    base action-type;
    description
      "dscp marking action type";
  }
  identity meter-inline {
    base action-type;
    description
      "meter-inline action type";
  }
  identity meter-reference {
    base action-type;
    description
      "meter reference action type";
  }
  identity queue {
    base action-type;
    description
      "queue action type";
  }
  identity scheduler {
    base action-type;
    description
      "scheduler action type";
  }
  identity discard {
    base action-type;
    description
      "discard action type";
  }
  identity child-policy {
    if-feature action:child-policy-feature;
    base action-type;
    description
      "child-policy action type";
  }
  identity count {
    if-feature action:count-feature;
    base action-type;
    description
      "count action type";
  }
  identity named-counter {
    if-feature action:named-counter-feature;
    base action-type;
    description
      "name counter action type";
  }

  grouping classifier-action-entry {
    description
      "List of Configuration of classifier & associated actions";
    list action {
      key "type";
      ordered-by user;
      description
        "Configuration of classifier & associated actions";
      leaf type {
        type identityref {
          base action-type;
        }
        description
          "This defines action type ";
      }
      choice action-params {
        description
          "Choice of action types";
      }
    }
  }
  container classifiers {
    if-feature classifier-template-feature;
    description
      "list of classifier entry";
    list classifier{
      key "name";
      description
        "each classifier entry contains a list of filters";
      uses generic-classifier-attr;
      list filter {
        key "type logical-not";
        uses filters;
        description
          "Filter entry configuration";
      }
    }
  }
  container policies{
    description
      "list of policy templates";
    list policy{
      key "name type";
      description
        "policy template";
      uses generic-policy-attr;
      list classifier{
        key "name";
        ordered-by user;
        description
          "Classifier entry configuration in a policy";
        leaf name {
          type string;
          description
            "classifier entry name";
        }
        uses inline-attr;
        uses classifier-action-entry;
      }
    }
  }
  augment "/if:interfaces/if:interface" {
    description
      "Augments Diffserv Target Entry to Interface module";
    list qos-target-policy {
      key "direction type";
      description
        "policy target for inbound or outbound direction";
      leaf direction {
        type identityref {
          base direction;
        }
        description
          "Direction of the traffic flow either inbound or outbound";
      }
      leaf type {
        type identityref {
          base policy-type;
        }
        description
          "Policy entry type";
      }
      leaf name {
        type string;
        mandatory true;
        description
          "Policy name";
      }
    }
  }
}

<CODE ENDS>
Figure 7: ietf-traffic-policy module

5.2. ietf-qos-action 

<CODE BEGINS>file "ietf-qos-action@2022-07-08.yang"
module ietf-qos-action {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-qos-action";
  prefix action;

  import ietf-inet-types {
    prefix inet;
    reference "RFC 6991: Common YANG Data Types";
  }

  organization
    "IETF Routing Area Working Group";

  contact
    "WG Web:   <https://datatracker.ietf.org/wg/rtgwg/>
     WG List:  <mailto:rtgwg@ietf.org>

     Editor:   Aseem Choudhary
               <mailto:achoudhary@aviatrix.com>
     Editor:   Mahesh Jethanandani
               <mailto:mjethanandani@gmail.com>";

  description
    "This module contains a collection of YANG definitions for
     configuring qos specification implementations.

     Copyright (c) 2021 IETF Trust and the persons identified as
     authors of the code.  All rights reserved.

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

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

  revision 2022-07-08 {
    description
      "Initial version";
    reference
      "RFC XXXX: YANG Models for Quality of Service (QoS).";
  }

  feature child-policy-feature {
    description
      " This feature allows configuration of hierarchical policy.";
  }
  feature count-feature {
    description
      "This feature allows action configuration to enable
       counter in a classifier";
  }
  feature named-counter-feature {
    description
      "This feature allows action configuration to enable
       named counter in a classifier";
  }
  identity rate-unit-type {
    description
      "base rate-unit type";
  }
  identity bits-per-second {
    base rate-unit-type;
    description
      "bits per second identity";
  }
  identity kilo-bits-per-second {
    base rate-unit-type;
    description
      "kilo bits per second identity";
  }
  identity mega-bits-per-second {
    base rate-unit-type;
    description
      "mega bits per second identity";
  }
  identity giga-bits-per-second {
    base rate-unit-type;
    description
      "mega bits per second identity";
  }
  identity percent {
    base rate-unit-type;
    description
      "percentage";
  }
  identity burst-unit-type {
    description
      "base burst-unit type";
  }
  identity bytes {
    base burst-unit-type;
    description
      "bytes";
  }
  identity kilo-bytes {
    base burst-unit-type;
    description
      "kilo bytes";
  }
  identity mega-bytes {
    base burst-unit-type;
    description
      "mega bytes";
  }
  identity millisecond {
    base burst-unit-type;
    description
      "milli seconds";
  }
  identity microsecond {
    base burst-unit-type;
    description
      "micro seconds";
  }
  identity red-threshold-unit {
    description
      "base red-unit type";
  }
  identity red-threshold-bytes {
    base red-threshold-unit;
    description
      "bytes";
  }
  identity red-threshold-kb {
    base red-threshold-unit;
    description
      "kilo bytes";
  }
  identity red-threshold-mb {
    base red-threshold-unit;
    description
      "mega bytes";
  }
  identity red-threshold-ms {
    base red-threshold-unit;
    description
      "milli seconds";
  }
  identity red-threshold-us {
    base red-threshold-unit;
    description
      "micro seconds";
  }
  identity red-threshold-pc {
    base red-threshold-unit;
    description
      "per-centage";
  }
  identity red-theshold-pt {
    base red-threshold-unit;
    description
      "per-thousand";
  }
  identity red-threshold-pm {
    base red-threshold-unit;
    description
      "per-million";
  }
  identity wred-color-type {
    description
      "base wred color type";
  }
  identity wred-color-dscp {
    base wred-color-type;
    description
      "dscp wred color type";
  }
  identity probability-unit {
    description
      "base probability unit type";
  }
  identity probability-pc {
    base probability-unit;
    description
      "probability in percentage";
  }
  identity probability-pt {
    base probability-unit;
    description
      "probability in per thousand";
  }
  identity probability-pm {
    base probability-unit;
    description
      "probability in per million";
  }
  identity probability-denominator {
    base probability-unit;
    description
      "probability value is denominator value
       while numerator is always 1";
  }
  identity meter-type {
    description
      "This base identity type defines meter types";
  }
  identity one-rate-two-color-meter-type {
    base meter-type;
    description
      "one rate two color meter type";
  }
  identity one-rate-tri-color-meter-type {
    base meter-type;
    description
      "one rate three color meter type";
  }
  identity two-rate-tri-color-meter-type {
    base meter-type;
    description
      "two rate three color meter action type";
  }

  identity drop-type {
    description
      "drop algorithm";
  }
  identity tail-drop {
    base drop-type;
    description
      "tail drop algorithm";
  }
  identity red {
    base drop-type;
    description
      "Random Early Detect drop algorithm";
  }
  identity wred {
    base drop-type;
    description
      "Weighted Random Early Detect drop algorithm";
  }

  identity conform-2color-meter-action-type {
    description
      "action type in a meter";
  }
  identity exceed-2color-meter-action-type {
    description
      "action type in a meter";
  }
  identity conform-3color-meter-action-type {
    description
      "action type in a meter";
  }
  identity exceed-3color-meter-action-type {
    description
      "action type in a meter";
  }
  identity violate-3color-meter-action-type {
    description
      "action type in a meter";
  }

  grouping rate-value-unit {
    leaf rate-value {
      type uint64;
      description
        "rate value";
    }
    leaf rate-unit {
      type identityref {
        base rate-unit-type;
      }
      description
        "rate unit";
    }
    description
      "rate value and unit grouping";
  }
  grouping burst {
    description
    "burst value and unit configuration";
    leaf burst-value {
      type uint64;
      description
        "burst value";
    }
    leaf burst-unit {
      type identityref {
        base burst-unit-type;
      }
      description
        "burst unit";
    }
  }

  grouping threshold {
    description
      "Threshold Parameters";
    container threshold {
      description
        "threshold";
      choice threshold-type {
        case size {
          leaf threshold-size {
            type uint64;
            units "bytes";
            description
              "Threshold size";
          }
        }
        case interval {
          leaf threshold-interval {
            type uint64;
            units "microsecond";
            description
              "Threshold interval";
          }
        }
        description
          "Choice of threshold type";
      }
    }
  }

  grouping drop {
    container drop {
      leaf drop-action {
        type empty;
        description
          "always drop algorithm";
      }
      description
        "the drop action";
    }
    description
      "always drop grouping";
  }

  grouping queuelimit {
    container qlimit-thresh {
      uses threshold;
      description
        "the queue limit";
    }
    description
      "the queue limit beyond which queue will not hold any packet";
  }

  grouping conform-2color-meter-action-params {
    description
      "meter action parameters";
    list conform-2color-meter-action-params {
      key "conform-2color-meter-action-type";
      ordered-by user;
      description
        "Configuration of basic-meter & associated actions";
      leaf conform-2color-meter-action-type {
        type identityref {
          base conform-2color-meter-action-type;
        }
        description
          "meter action type";
      }
      choice conform-2color-meter-action-val {
        description
          " meter action based on choice of meter action type";
      }
    }
  }

  grouping exceed-2color-meter-action-params {
    description
      "meter action parameters";
    list exceed-2color-meter-action-params {
      key "exceed-2color-meter-action-type";
      ordered-by user;
      description
        "Configuration of basic-meter & associated actions";
      leaf exceed-2color-meter-action-type {
        type identityref {
          base exceed-2color-meter-action-type;
        }
        description
          "meter action type";
      }
      choice exceed-2color-meter-action-val {
        description
          " meter action based on choice of meter action type";
      }
    }
  }


  grouping conform-3color-meter-action-params {
    description
      "meter action parameters";
    list conform-3color-meter-action-params {
      key "conform-3color-meter-action-type";
      ordered-by user;
      description
        "Configuration of basic-meter & associated actions";
      leaf conform-3color-meter-action-type {
        type identityref {
          base conform-3color-meter-action-type;
        }
        description
          "meter action type";
      }
      choice conform-3color-meter-action-val {
        description
          " meter action based on choice of meter action type";
      }
    }
  }

  grouping exceed-3color-meter-action-params {
    description
      "meter action parameters";
    list exceed-3color-meter-action-params {
      key "exceed-3color-meter-action-type";
      ordered-by user;
      description
        "Configuration of basic-meter & associated actions";
      leaf exceed-3color-meter-action-type {
        type identityref {
          base exceed-3color-meter-action-type;
        }
        description
          "meter action type";
      }
      choice exceed-3color-meter-action-val {
        description
          " meter action based on choice of meter action type";
      }
    }
  }

  grouping violate-3color-meter-action-params {
    description
      "meter action parameters";
    list violate-3color-meter-action-params {
      key "violate-3color-meter-action-type";
      ordered-by user;
      description
        "Configuration of basic-meter & associated actions";
      leaf violate-3color-meter-action-type {
        type identityref {
          base violate-3color-meter-action-type;
        }
        description
          "meter action type";
      }
      choice violate-3color-meter-action-val {
        description
          " meter action based on choice of meter action type";
      }
    }
  }

  grouping one-rate-two-color-meter {
    container one-rate-two-color-meter {
      description
        "single rate two color marker meter";
      leaf committed-rate-value {
        type uint64;
        description
          "committed rate value";
      }
      leaf committed-rate-unit {
        type identityref {
          base rate-unit-type;
        }
        description
          "committed rate unit";
      }
      leaf committed-burst-value {
        type uint64;
        description
          "burst value";
      }
      leaf committed-burst-unit {
        type identityref {
          base burst-unit-type;
        }
        description
          "committed burst unit";
      }
      container conform-action {
        uses conform-2color-meter-action-params;
        description
          "conform action";
      }
      container exceed-action {
        uses exceed-2color-meter-action-params;
        description
          "exceed action";
      }
    }
    description
      "single rate two color marker meter attributes";
  }

  grouping one-rate-tri-color-meter {
    container one-rate-tri-color-meter {
      description
        "single rate three color meter";
    leaf committed-rate-value {
      type uint64;
      description
        "meter rate";
    }
    leaf committed-rate-unit {
      type identityref {
        base rate-unit-type;
      }
      description
        "committed rate unit";
    }
    leaf committed-burst-value {
      type uint64;
      description
        "committed burst size";
    }
    leaf committed-burst-unit {
      type identityref {
        base burst-unit-type;
      }
      description
        "committed burst unit";
    }
    leaf excess-burst-value {
      type uint64;
      description
        "excess burst size";
    }
    leaf excess-burst-unit {
      type identityref {
        base burst-unit-type;
      }
      description
        "excess burst unit";
    }
    container conform-action {
      uses conform-3color-meter-action-params;
      description
        "conform, or green action";
    }
    container exceed-action {
      uses exceed-3color-meter-action-params;
      description
        "exceed, or yellow action";
    }
    container violate-action {
      uses violate-3color-meter-action-params;
      description
        "violate, or red action";
    }
  }
    description
      "one-rate-tri-color-meter attributes";
  }

  grouping two-rate-tri-color-meter {
    container two-rate-tri-color-meter {
      description
        "two rate three color meter";
    leaf committed-rate-value {
      type uint64;
      units "bits-per-second";
      description
        "committed rate";
    }
    leaf committed-rate-unit {
      type identityref {
        base rate-unit-type;
      }
      description
        "committed rate unit";
    }
    leaf committed-burst-value {
      type uint64;
      description
        "commited burst size";
    }
    leaf committed-burst-unit {
      type identityref {
        base burst-unit-type;
      }
      description
        "committed burst unit";
    }
    leaf peak-rate-value {
      type uint64;
      description
        "peak rate";
    }
    leaf peak-rate-unit {
      type identityref {
        base rate-unit-type;
      }
      description
        "committed rate unit";
    }
    leaf peak-burst-value {
      type uint64;
      description
        "commited burst size";
    }
    leaf peak-burst-unit {
      type identityref {
        base burst-unit-type;
      }
      description
        "peak burst unit";
    }
    container conform-action {
      uses conform-3color-meter-action-params;
      description
        "conform, or green action";
    }
    container exceed-action {
      uses exceed-3color-meter-action-params;
      description
        "exceed, or yellow action";
    }
    container violate-action {
      uses violate-3color-meter-action-params;
      description
        "exceed, or red action";
    }
  }
    description
      "two-rate-tri-color-meter attributes";
  }

  grouping meter {
    choice meter-type {
      case one-rate-two-color-meter-type {
        uses one-rate-two-color-meter;
        description
          "basic meter";
      }
      case one-rate-tri-color-meter-type {
        uses one-rate-tri-color-meter;
        description
          "one rate tri-color meter";
      }
      case two-rate-tri-color-meter-type {
        uses two-rate-tri-color-meter;
        description
          "two rate tri-color meter";
      }
      description
        " meter action based on choice of meter action type";
    }
    description
      "meter attributes";
  }

  container meters {
    description
      "list of meter templates";
    list meter {
      key "name";
      description
        "meter entry template";
      leaf name {
        type string;
        description
          "meter identifier";
      }
      uses meter;
    }
  }

  grouping meter-reference {
    container meter {
      leaf name {
        type string ;
        mandatory true;
        description
          "This leaf defines name of the meter referenced";
      }
      leaf type {
        type identityref {
          base meter-type;
        }
        mandatory true;
        description
          "This leaf defines type of the meter";
      }
      description
        "meter reference name";
    }
    description
      "meter reference";
  }

  grouping count {
    container count {
    if-feature count-feature;
      leaf count-action {
        type empty;
        description
          "count action";
      }
      description
        "the count action";
    }
    description
      "the count action grouping";
  }

  grouping named-counter {
    container named-counter {
    if-feature named-counter-feature;
      leaf count-name-action {
        type string;
        description
          "count action";
      }
      description
        "the count action";
    }
    description
      "the count action grouping";
  }

  grouping discard {
    container discard {
      leaf discard {
        type empty;
        description
          "discard action";
      }
      description
        "discard action";
    }
    description
      "discard grouping";
  }

  grouping priority {
    container priority {
      leaf priority-level {
        type uint8;
        description
          "priority level";
      }
      description
        "priority attributes";
    }
    description
      "priority attributes grouping";
  }
  grouping min-rate {
    container min-rate {
      uses rate-value-unit;
      description
        "min guaranteed bandwidth";
    }
    description
      "minimum rate grouping";
  }
  grouping dscp-marking {
    container dscp {
      leaf dscp {
        type inet:dscp;
        description
          "dscp marking";
      }
      description
        "dscp marking container";
    }
    description
      "dscp marking grouping";
  }
  grouping traffic-group-marking {
    container traffic-group {
      leaf traffic-group {
        type string;
        description
          "traffic group marking";
      }
      description
        "traffic group marking container";
    }
    description
      "traffic group marking grouping";
  }
  grouping child-policy {
    container child-policy {
      if-feature child-policy-feature;
      leaf policy-name {
        type string;
        description
          "Hierarchical Policy";
      }
      description
        "Hierarchical Policy configuration container";
    }
    description
      "Grouping of Hierarchical Policy configuration";
  }
  grouping max-rate {
    container max-rate {
      uses rate-value-unit;
      uses burst;
      description
        "maximum rate attributes container";
    }
    description
      "maximum rate attributes";
  }
  grouping red-config-parameters {
    leaf min-threshold-val {
      type uint64;
      description
       "minimum value of red threshold";
    }
    leaf min-threshold-unit {
      type identityref {
        base red-threshold-unit;
      }
      description
       "unit of minimum red threshold";
    }
    leaf max-threshold-val {
      type uint64;
      description
       "maximum value of red threshold";
    }
    leaf max-threshold-unit {
      type identityref {
        base red-threshold-unit;
      }
      description
       "unit of maximum red threshold";
    }
    leaf weight {
      type uint8;
      description
       "the decay factor for the average queue size
        calculation. the numbers are 2's exponent";
    }
    leaf max-probability-val {
      type uint64;
      description
       "value of maximum probability value. this value need
        be interpreted along with max-probability-unit";
    }
    leaf max-probability-unit {
      type identityref {
        base probability-unit;
      }
      description
       "probability unit type as defined
        by probability-unit";
    }
    description
      "Random Early Detect Configuration Parameters";
  }
  grouping queue {
    container queue {
      uses priority;
      uses min-rate;
      uses max-rate;
      container algorithmic-drop {
        choice drop-algorithm {
          case tail-drop {
            container tail-drop {
              leaf tail-drop {
                type empty;
                description
                 "tail drop algorithm";
              }
              description
                "Tail Drop configuration container";
            }
            description
              "Tail Drop choice";
          }
          case red {
            container red {
              uses red-config-parameters;
              leaf ecn-enabled {
                type boolean;
                default "false";
                description
                  "ecn is enabled on the queue";
              }
              description
                "Random Early Detect configuration";
            }
          }
          case wred {
            container wred {
              list wred {
                key "profile";
                leaf profile {
                  type uint8;
                  description
                    "profile id of each wred profile";
                }
                leaf color-type {
                  type identityref {
                    base wred-color-type;
                  }
                  description
                    "wred color-type of each profile";
                }
                list color-val {
                  key "min max";
                  leaf min {
                    type uint8;
                    description
                      "minimum value of color types";
                  }
                  leaf max {
                    type uint8;
                    description
                      "maximum value of color types";
                  }
                  description
                    "list of color markings which constitute
                     a traffic profile";
                }
                uses red-config-parameters;
                description
                  "list of RED profiles each with its own
                   threshold values";
              }
              leaf ecn-enabled {
                type boolean;
                default "false";
                description
                  "ecn is enabled on the queue";
              }
              description
                "Weighted Random Early Detect configuration";
            }
          }
          description
            "Choice of Drop Algorithm";
        }
        description
          "Algorithmic Drop configuration container";
      }
      description
        "Queue configuration container";
    }
    description
      "Queue grouping";
  }
  grouping scheduler {
    container scheduler {
      uses min-rate;
      uses max-rate;
      description
        "Schedular configuration container";
    }
    description
      "Schedular configuration grouping";
  }
}

<CODE ENDS>
Figure 8: ietf-qos-actions module

5.3. ietf-diffserv 

<CODE BEGINS>file "ietf-diffserv@2022-07-08.yang"
module ietf-diffserv {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-diffserv";
  prefix diffserv;

  import ietf-traffic-policy {
    prefix policy;
  }
  import ietf-qos-action {
    prefix action;
  }
  import ietf-inet-types {
    prefix inet;
  }

  organization
    "IETF Routing Area Working Group";

  contact
    "WG Web:   <https://datatracker.ietf.org/wg/rtgwg/>
     WG List:  <mailto:rtgwg@ietf.org>

     Editor:   Aseem Choudhary
               <mailto:achoudhary@aviatrix.com>
     Editor:   Mahesh Jethanandani
               <mailto:mjethanandani@gmail.com>";

  description
    "This module contains a collection of YANG definitions for
     configuring diffserv specification implementations.

     Copyright (c) 2021 IETF Trust and the persons identified as
     authors of the code.  All rights reserved.

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

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

  revision 2022-07-08 {
    description
      "Initial version";
    reference
      "RFC XXXX: A YANG Model for Quality of Service (QoS)";
  }

  identity meter-type {
    description
      "This base identity type defines meter types";
  }
  identity one-rate-two-color-meter-type {
    base meter-type;
    description
      "one rate two color meter type";
  }
  identity one-rate-tri-color-meter-type {
    base meter-type;
    description
      "one rate three color meter type";
  }
  identity two-rate-tri-color-meter-type {
    base meter-type;
    description
      "two rate three color meter action type";
  }
  grouping dscp {
    list dscp {
      key "dscp-min dscp-max";
      description
        "list of dscp ranges";
      leaf dscp-min {
        type inet:dscp;
        description
          "Minimum value of dscp min-max range";
      }
      leaf dscp-max {
        type inet:dscp;
        must ". >= ../dscp-min" {
          error-message
          "The dscp-max must be greater than or equal to dscp-min";
        }
        description
          "maximum value of dscp min-max range";
      }
    }
    description
      "Filter grouping containing list of dscp ranges";
  }
  grouping source-ipv4-prefix {
    list source-ipv4-prefix {
      key "source-ipv4-prefix";
      description
        "list of source ipv4 prefix";
      leaf source-ipv4-prefix {
        type inet:ipv4-prefix;
        description
          "source ipv4 prefix";
      }
    }
    description
      "Filter grouping containing list of source ipv4 prefixes";
  }
  grouping destination-ipv4-prefix {
    list destination-ipv4-prefix {
      key "destination-ipv4-prefix";
      description
        "list of destination ipv4 prefix";
      leaf destination-ipv4-prefix {
        type inet:ipv4-prefix;
        description
          "destination ipv4 prefix";
      }
    }
    description
      "Filter grouping containing list of destination ipv4 prefix";
  }
  grouping source-ipv6-prefix {
    list source-ipv6-prefix {
      key "source-ipv6-prefix";
      description
        "list of source ipv6 prefix";
      leaf source-ipv6-prefix {
        type inet:ipv6-prefix;
        description
          "source ipv6 prefix";
      }
    }
    description
      "Filter grouping containing list of source ipv6 prefixes";
  }
  grouping destination-ipv6-prefix {
    list destination-ipv6-prefix {
      key "destination-ipv6-prefix";
      description
        "list of destination ipv4 or ipv6 prefix";
      leaf destination-ipv6-prefix {
        type inet:ipv6-prefix;
        description
          "destination ipv6 prefix";
      }
    }
    description
      "Filter grouping containing list of destination ipv6 prefix";
  }
  grouping source-port {
    list source-port {
      key "source-port-min source-port-max";
      description
        "list of ranges of source port";
      leaf source-port-min {
        type inet:port-number;
        description
          "minimum value of source port range";
      }
      leaf source-port-max {
        type inet:port-number;
        must ". >= ../source-port-min" {
          error-message
          "The source-port-max must be greater than or equal to
           source-port-min";
        }
        description
          "maximum value of source port range";
      }
    }
    description
      "Filter grouping containing list of source port ranges";
  }
  grouping destination-port {
    list destination-port {
      key "destination-port-min destination-port-max";
      description
        "list of ranges of destination port";
      leaf destination-port-min {
        type inet:port-number;
        description
          "minimum value of destination port range";
      }
      leaf destination-port-max {
        type inet:port-number;
        must ". >= ../destination-port-min" {
          error-message
          "The destination-port-max must be greater than or equal to
           destination-port-min";
        }
        description
          "maximum value of destination port range";
      }
    }
    description
      "Filter grouping containing list of destination port ranges";
  }
  grouping protocol {
    list protocol {
      key "protocol-min protocol-max";
      description
        "list of ranges of protocol values. Protocol refers to the
         value in the protocol field of the ipv4 header and value
         in the 'next-header' field of ipv6 header. In ipv6 header,
         'next-header' field indicates first extension header or the
          protocol in the 'upper-layer' header.";
      reference
        "RFC 791: Internet Protocol
         RFC 8200: Internet Protocol, Version 6 (IPv6)
                   Specification";
      leaf protocol-min {
        type uint8 {
          range "0..255";
        }
        description
          "minimum value of protocol range";
      }
      leaf protocol-max {
        type uint8 {
          range "0..255";
        }
        must ". >= ../protocol-min" {
          error-message
          "The protocol-max must be greater than or equal to
           protocol-min";
        }
        description
          "maximum value of protocol range";
      }
    }
    description
      "Filter grouping containing list of Protocol ranges";
  }
  grouping traffic-group {
    container traffic-group {
      leaf traffic-group-name {
        type string ;
        description
          "This leaf defines name of the traffic group referenced";
      }
    description
      "traffic group container";
    }
    description
      "traffic group grouping";
  }

  augment "/policy:classifiers/policy:classifier" +
          "/policy:filter" {
    choice filter-param {
      description
        "Choice of filter types";
      case dscp {
        uses dscp;
        description
          "Filter containing list of dscp ranges";
      }
      case source-ipv4-prefix {
        uses source-ipv4-prefix;
        description
          "Filter containing list of source ipv4 prefixes";
      }
      case destination-ipv4-prefix {
        uses destination-ipv4-prefix;
        description
          "Filter containing list of destination ipv4 prefix";
      }
      case source-ipv6-prefix {
        uses source-ipv6-prefix;
        description
          "Filter containing list of source ipv6 prefixes";
      }
      case destination-ipv6-prefix {
        uses destination-ipv6-prefix;
        description
          "Filter containing list of destination ipv6 prefix";
      }
      case source-port {
        uses source-port;
        description
          "Filter containing list of source-port ranges";
      }
      case destination-port {
        uses destination-port;
        description
          "Filter containing list of destination-port ranges";
      }
      case protocol {
        uses protocol;
        description
          "Filter Type Protocol";
      }
      case traffic-group {
        uses traffic-group;
        description
          "Filter Type traffic-group";
      }
    }
    description
      "augments diffserv filters to qos classifier";
  }
  augment "/policy:policies/policy:policy/policy:classifier" +
          "/policy:filter" {
    when "../../policy:type = 'diffserv:ipv4-diffserv-policy-type' or
          ../../policy:type = 'diffserv:ipv6-diffserv-policy-type' or
          ../../policy:type = 'diffserv:diffserv-policy-type'" {
      description
        "If policy type is v4, v6 or default diffserv,
         this filter can be used.";
    }
    choice filter-params {
      description
        "Choice of action types";
      case dscp {
        uses dscp;
        description
          "Filter containing list of dscp ranges";
      }
      case source-ipv4-prefix {
        when "/policy:policies/policy:policy/policy:type != " +
             "'diffserv:ipv6-diffserv-policy-type'" {
            description
               "If policy type is v6, this filter cannot be used.";
        }
        uses source-ipv4-prefix;
        description
          "Filter containing list of source ipv4 prefixes";
      }
      case destination-ipv4-prefix {
        when "/policy:policies/policy:policy/policy:type != " +
             "'diffserv:ipv6-diffserv-policy-type'" {
            description
               "If policy type is v6, this filter cannot be used.";
        }
        uses destination-ipv4-prefix;
        description
          "Filter containing list of destination ipv4 prefix";
      }
      case source-ipv6-prefix {
        when "/policy:policies/policy:policy/policy:type != "+
             "'diffserv:ipv4-diffserv-policy-type'" {
            description
               "If policy type is v4, this filter cannot be used.";
        }
        uses source-ipv6-prefix;
        description
          "Filter containing list of source ipv6 prefixes";
      }
      case destination-ipv6-prefix {
        when "/policy:policies/policy:policy/policy:type != " +
             "'diffserv:ipv4-diffserv-policy-type'" {
            description
               "If policy type is v4, this filter cannot be used.";
        }
        uses destination-ipv6-prefix;
        description
          "Filter containing list of destination ipv6 prefix";
      }
      case source-port {
        uses source-port;
        description
          "Filter containing list of source-port ranges";
      }
      case destination-port {
        uses destination-port;
        description
          "Filter containing list of destination-port ranges";
      }
      case protocol {
        uses protocol;
        description
          "Filter Type Protocol";
      }
      case traffic-group {
        uses traffic-group;
        description
          "Filter Type traffic-group";
      }
    }
    description
      "Augments Diffserv Classifier with common filter types";
  }
  augment "/policy:policies/policy:policy/policy:classifier" +
          "/policy:action/policy:action-params" {
    when "../../policy:type = 'diffserv:ipv4-diffserv-policy-type' or
          ../../policy:type = 'diffserv:ipv6-diffserv-policy-type' or
          ../../policy:type = 'diffserv:diffserv-policy-type' " {
      description
        "If policy type is v4, v6 or default diffserv,
         these actions can be used.";
    }
    description
      "Augments Diffserv Policy with action configuration";

    case dscp-marking {
      uses action:dscp-marking;
    }
    case meter-inline {
      uses action:meter;
    }
    case meter-reference {
      uses action:meter-reference;
    }
    case traffic-group-marking {
      uses action:traffic-group-marking;
    }
    case child-policy {
      if-feature action:child-policy-feature;
      uses action:child-policy;
    }
    case count {
      if-feature action:count-feature;
      uses action:count;
    }
    case named-count {
      if-feature action:named-counter-feature;
      uses action:named-counter;
    }
    case queue-inline {
      uses action:queue;
    }
    case scheduler-inline {
      uses action:scheduler;
    }
  }
}

<CODE ENDS>
Figure 9: ietf-diffserv module

5.4. ietf-queue-policy 

<CODE BEGINS>file "ietf-queue-policy@2022-07-08.yang"
module ietf-queue-policy {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-queue-policy";
  prefix queue-policy;

  import ietf-traffic-policy {
    prefix policy;
  }
  import ietf-qos-action {
    prefix action;
  }
  import ietf-diffserv {
    prefix diffserv;
  }

  organization
    "IETF Routing Area Working Group";

  contact
    "WG Web:   <https://datatracker.ietf.org/wg/rtgwg/>
     WG List:  <mailto:rtgwg@ietf.org>

     Editor:   Aseem Choudhary
               <mailto:achoudhary@aviatrix.com>
     Editor:   Mahesh Jethanandani
               <mailto:mjethanandani@gmail.com>";

  description
    "This module contains a collection of YANG definitions for
     configuring diffserv specification implementations.

     Copyright (c) 2021 IETF Trust and the persons identified as
     authors of the code.  All rights reserved.

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

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

  revision 2022-07-08 {
    description
      "Initial version";
    reference
      "RFC XXXX: YANG Models for Quality of Service (QoS).";
  }

  identity queue-policy-type {
    base policy:policy-type;
    description
      "This defines queue policy-type";
  }

  augment "/policy:policies/policy:policy/policy:classifier" +
          "/policy:filter" {
    when "../../policy:type = 'queue-policy:queue-policy-type'" {
      description
        "If policy type is queue policy, this filter can be used.";
    }
    choice filter-params {
      description
        "Choice of action types";
      case traffic-group-name {
        uses diffserv:traffic-group;
        description
          "traffic group name";
      }
    }
    description
      "Augments Queue policy Classifier with common filter types";
  }

  identity queue-template-name {
    base policy:action-type;
    description
      "queue template name";
  }

  grouping queue-reference {
    container queue-reference {
      leaf queue-name {
        type string;
        mandatory true;
        description
          "This leaf defines name of the  queue template referenced";
      }
      description
        "queue template reference";
    }
    description
      "queue template reference grouping";
  }

  container queue {
    description
      "Queue template";
    leaf name {
      type string;
      description
        "A unique name identifying this queue template";
    }
    uses action:queue;
  }
  augment "/policy:policies/policy:policy/policy:classifier" +
          "/policy:action/policy:action-params" {
    when "../../policy:type = 'queue-policy:queue-policy-type'" {
      description
        "queue policy actions.";
    }
    case queue-template-name {
      uses queue-reference;
    }
    case queue-inline {
      uses action:queue;
    }
    description
      "augments queue template reference to queue policy";
  }
}

<CODE ENDS>
Figure 10: ietf-queue-policy module

5.5. ietf-scheduler-policy 

<CODE BEGINS>file "ietf-scheduler-policy@2022-07-08.yang"
module ietf-scheduler-policy {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-scheduler-policy";
  prefix scheduler-policy;

  import ietf-traffic-policy {
    prefix policy;
  }
  import ietf-qos-action {
    prefix action;
  }

  organization
    "IETF Routing Area Working Group";

  contact
    "WG Web:   <https://datatracker.ietf.org/wg/rtgwg/>
     WG List:  <mailto:rtgwg@ietf.org>

     Editor:   Aseem Choudhary
               <mailto:achoudhary@aviatrix.com>
     Editor:   Mahesh Jethanandani
               <mailto:mjethanandani@gmail.com>";

  description
    "This module contains a collection of YANG definitions for
     configuring diffserv specification implementations.

     Copyright (c) 2021 IETF Trust and the persons identified as
     authors of the code.  All rights reserved.

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

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

  revision 2022-07-08 {
    description
      "Initial version";
    reference
      "RFC XXXX: YANG Models for Quality of Service (QoS).";
  }

  identity scheduler-policy-type {
    base policy:policy-type;
    description
      "This defines scheduler policy-type";
  }

  identity filter-match-all {
    base policy:filter-type;
    description
      "Traffic-group filter type";
  }

  grouping filter-match-all {
    container match-all-cfg {
      leaf match-all-action {
        type empty;
        description
          "match all packets";
      }
      description
        "the match-all action";
    }
    description
      "the match-all filter grouping";
  }

  augment "/policy:policies/policy:policy/policy:classifier" +
          "/policy:filter" {
        when "../../policy:type =" +
             "'scheduler-policy:scheduler-policy-type'" {
            description
               "Only when policy type is scheduler-policy";
        }
    choice filter-params {
      description
        "Choice of action types";
      case filter-match-all {
        uses filter-match-all;
        description
          "filter match-all";
      }
    }
    description
      "Augments Queue policy Classifier with common filter types";
  }

  identity queue-policy-name {
    base policy:action-type;
    description
      "queue policy name";
  }

  grouping queue-policy-name-cfg {
    container queue-policy-name {
      leaf queue-policy {
        type string ;
        mandatory true;
        description
          "This leaf defines name of the queue-policy";
      }
    description
      "container for queue-policy name";
    }
    description
      "queue-policy name grouping";
  }


  augment "/policy:policies/policy:policy/policy:classifier" +
          "/policy:action/policy:action-params" {
        when "../../policy:type =" +
             "'scheduler-policy:scheduler-policy-type'" {
            description
               "Only when policy type is scheduler-policy";
        }
      case scheduler {
        uses action:scheduler;
      }
      case queue-policy-name {
        uses queue-policy-name-cfg;
      }
    description
      "augments scheduler template reference to scheduler policy";
  }
}

<CODE ENDS>
Figure 11: ietf-scheduler-policy module

5.6. ietf-qos-oper 

<CODE BEGINS>file "ietf-qos-oper@2022-07-08.yang"
module ietf-qos-oper {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-qos-oper";
  prefix oper;

  import ietf-yang-types {
    prefix yang;
    reference
      "RFC 6991:Common YANG Data Types";
  }
  import ietf-interfaces {
    prefix if;
    reference
      "RFC8343: A YANG Data Model for Interface Management";
  }

  organization "IETF RTG (Routing Area) Working Group";

  contact
    "WG Web:   <http://tools.ietf.org/wg/rtgwg/>
     WG List:  <mailto:rtgwg@ietf.org>
     Editor:   Aseem Choudhary
               <mailto:achoudhary@aviatrix.com>
     Editor:   Mahesh Jethanandani
               <mailto:mjethanandani@gmail.com>";
  description
    "This module contains a collection of YANG definitions for
     qos operational specification.

     Copyright (c) 2021 IETF Trust and the persons identified as
     authors of the code.  All rights reserved.

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

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

  revision 2022-07-08 {
    description
      "Initial version";
    reference
      "RFC XXXX: YANG Models for Quality of Service (QoS).";
  }

  identity direction {
    description
      "This is a base identity of traffic direction";
  }
  identity inbound {
    base direction;
    description
      "Direction of traffic coming into the network entry";
  }
  identity outbound {
    base direction;
    description
      "Direction of traffic going out of the network entry";
  }

  grouping named-stats {
    description
      "QoS matching statistics associated with a stats-name";
    leaf pkts {
      type yang:zero-based-counter64;
      description
        " Number of total matched packets associated
          to a statistics name";
    }
    leaf bytes {
      type yang:zero-based-counter64;
      description
        " Number of total matched bytes associated
          to a statistics name";
    }
    leaf rate {
      type yang:gauge64;
      units "bits-per-second";
      description
        " Rate of average matched data which is associated
          to a statistics name";
    }
  }
  grouping meter-stats {
    description
      "Metering counters";
    leaf conform-pkts {
      type yang:zero-based-counter64;
      description
        "Number of packets within conform rate and burst";
    }
    leaf conform-bytes {
      type yang:zero-based-counter64;
      description
        "Total bytes count within conform rate and burst";
    }
    leaf conform-rate {
      type yang:gauge64;
      units "bits-per-second";
      description
        "Traffic Rate measured as conformimg";
    }
    leaf exceed-pkts {
      type yang:zero-based-counter64;
      description
        "Number of non-conforming packets which are within peak rate
         and peak burst";
    }
    leaf exceed-bytes {
      type yang:zero-based-counter64;
      description
        "Total non-conforming bytes count which is within peak rate
         and peak burst";
    }
    leaf exceed-rate {
      type yang:gauge64;
      units "bits-per-second";
      description
        "Traffic Rate measured as exceeding";
    }
    leaf violate-pkts {
      type yang:zero-based-counter64;
      description
        "Number of packets which are beyond peak rate
         and peak burst";
    }
    leaf violate-bytes {
      type yang:zero-based-counter64;
      description
        "Total bytes count which is beyond peak rate and peak burst";
    }
    leaf violate-rate {
      type yang:gauge64;
      units "bits-per-second";
      description
        "Traffic Rate measured as violating";
    }
    leaf meter-drop-pkts {
      type yang:zero-based-counter64;
      description
        "Number of packets dropped by meter";
    }
    leaf meter-drop-bytes {
      type yang:zero-based-counter64;
      description
        "Bytes of packets dropped by meter";
    }
  }
  grouping classifier-entry-statistics {
    description
      "Statistics for a classifier entry";
    leaf classifier-entry-name {
      type string;
      description
        "Classifier Entry Name";
    }
    leaf classified-pkts {
      type yang:zero-based-counter64;
      description
        " Number of total packets which filtered
          to a classifier-entry";
    }
    leaf classified-bytes {
      type yang:zero-based-counter64;
      description
        " Number of total bytes which filtered
          to a classifier-entry";
    }
    leaf classified-rate {
      type yang:gauge64;
      units "bits-per-second";
      description
        " Rate of average data flow through a
          classifier-entry";
    }
  }
  grouping queuing-stats {
    description
      "Statistics for a queue";
    leaf queue-id {
      type string;
      description
        "Queue Identifier";
    }
    leaf transmit-pkts {
      type yang:zero-based-counter64;
      description
        "Number of packets transmitted from queue";
    }
    leaf transmit-bytes {
      type yang:zero-based-counter64;
      description
        "Number of bytes transmitted from queue";
    }
    leaf queue-current-size-bytes {
      type yang:gauge64;
      description
        "Number of bytes currently buffered";
    }
    leaf queue-average-size-bytes {
      type yang:gauge64;
      description
        "Average queue size in number of bytes";
    }
    leaf queue-peak-size-bytes {
      type yang:gauge64;
      description
        "Peak buffer queue size in bytes";
    }
    leaf tail-drop-pkts {
      type yang:zero-based-counter64;
      description
        "Total number of packets tail-dropped";
    }
    leaf tail-drop-bytes {
      type yang:zero-based-counter64;
      description
        "Total number of bytes tail-dropped";
    }
    leaf red-drop-pkts {
      type yang:zero-based-counter64;
      description
        "Total number of packets dropped through RED mechanism";
    }
    leaf red-drop-bytes {
      type yang:zero-based-counter64;
      description
        "Total number of bytes dropped through RED mechanism";
    }
    leaf red-ecn-marked-pkts {
      type yang:zero-based-counter64;
      description
        "Total number of packets ECN marked through RED mechanism";
    }
    leaf red-ecn-marked-bytes {
      type yang:zero-based-counter64;
      description
        "Total number of bytes ECN marked through RED mechanism";
    }
    list wred-stats {
      config false;
      description
        "Qos WRED statistics";
      leaf profile {
        type uint8;
        description
          "profile identifier for each color of traffic";
      }
      leaf drop-pkts {
        type yang:zero-based-counter64;
        description
          "Total number of packets dropped through WRED mechanism";
      }
      leaf drop-bytes {
        type yang:zero-based-counter64;
        description
          "Total number of bytes dropped through WRED mechanism";
      }
      leaf ecn-marked-pkts {
        type yang:zero-based-counter64;
        description
          "Total number of packets ECN marked through
           WRED mechanism";
      }
      leaf ecn-marked-bytes {
        type yang:zero-based-counter64;
        description
          "Total number of bytes ECN marked through WRED mechanism";
      }
    }
  }
  grouping metering-stats {
    description
      "Statistics for a meter";
    leaf meter-id {
      type string;
      description
        "Meter Identifier";
    }
    uses meter-stats;
  }

  augment "/if:interfaces/if:interface" {
    description
      "Augments Qos Target Entry to Interface module";

    container qos-interface-statistics {
      config false;
      description
        "Qos Interface statistics";

      list stats-per-direction {
        description
          "Qos Interface statistics for ingress or egress direction";

        leaf direction {
          type identityref {
            base direction;
          }
          description
            "Direction of the traffic flow either inbound
             or outbound";
        }
        leaf policy-name {
          type string;
          description
            "Policy entry name for single level policy as well as
             for Hierarchical policies. For Hierarchical policies,
             this represent relative path as well as the last level
             policy name.";
        }

        list classifier-statistics {
          description
            "Classifier Statistics for each Classifier Entry in a
             Policy applied in a particular direction";
          uses classifier-entry-statistics;
        }
        list named-statistics {
          description
            "Statistics for a statistics-name";
          leaf name {
            type string;
            description
              "Statistics name";
          }
          container aggregated {
            description
              "Matched aggregated statistics for a statistics-name";
            uses named-stats;
          }
          container non-aggregated {
            description
              "Statistics for non-aggregated statistics-name";
            list classifier-statistics {
              description
                "Classifier Statistics for each Classifier Entry in a
                 Policy applied in a particular direction";
              uses classifier-entry-statistics;
            }
            list metering-statistics {
              description
                "Statistics for each Meter associated with
                 the Policy";
              reference
                "RFC2697: A Single Rate Three Color Marker
                 RFC2698: A Two Rate Three Color Marker";
              uses metering-stats;
            }
            list queueing-statistics {
              description
                "Statistics for each Queue associated with
                 the Policy";
              uses queuing-stats;
            }
          }
        }
        list metering-statistics {
          description
            "Statistics for each Meter associated with the Policy";
          reference
            "RFC2697: A Single Rate Three Color Marker
             RFC2698: A Two Rate Three Color Marker";
          uses metering-stats;
        }
        list queueing-statistics {
          description
            "Statistics for each Queue associated with the Policy";
          uses queuing-stats;
        }
      }
    }
  }
}

<CODE ENDS>
Figure 12: ietf-qos-oper module

6. IANA Considerations

TBD

7. Security Considerations

8. Acknowledgement

The authors wish to thank Ruediger Geib, Fred Baker, Greg Misky, Tom Petch, Acee Lindem, many others for their helpful comments.

MITRE has approved this document for Public Release, Distribution Unlimited, with Public Release Case Number 19-3027.

9. Contributors

The following people have substantially contributed to the editing of this document:

    Norm Strahle
    Email: nstrahle@juniper.net       .

10. References

10.1. Normative References

[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/info/rfc2119>.
[RFC2697]
Heinanen, J. and R. Guerin, "A Single Rate Three Color Marker", RFC 2697, DOI 10.17487/RFC2697, , <https://www.rfc-editor.org/info/rfc2697>.
[RFC2698]
Heinanen, J. and R. Guerin, "A Two Rate Three Color Marker", RFC 2698, DOI 10.17487/RFC2698, , <https://www.rfc-editor.org/info/rfc2698>.
[RFC8342]
Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K., and R. Wilton, "Network Management Datastore Architecture (NMDA)", RFC 8342, DOI 10.17487/RFC8342, , <https://www.rfc-editor.org/info/rfc8342>.
[RFC3289]
Baker, F., Chan, K., and A. Smith, "Management Information Base for the Differentiated Services Architecture", RFC 3289, DOI 10.17487/RFC3289, , <https://www.rfc-editor.org/info/rfc3289>.
[RFC6020]
Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, , <https://www.rfc-editor.org/info/rfc6020>.
[RFC6991]
Schoenwaelder, J., Ed., "Common YANG Data Types", RFC 6991, DOI 10.17487/RFC6991, , <https://www.rfc-editor.org/info/rfc6991>.
[RFC7950]
Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, , <https://www.rfc-editor.org/info/rfc7950>.
[RFC8174]
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <https://www.rfc-editor.org/info/rfc8174>.
[RFC8343]
Bjorklund, M., "A YANG Data Model for Interface Management", RFC 8343, DOI 10.17487/RFC8343, , <https://www.rfc-editor.org/info/rfc8343>.

10.2. Informative References

[RFC2474]
Nichols, K., Blake, S., Baker, F., and D. Black, "Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers", RFC 2474, DOI 10.17487/RFC2474, , <https://www.rfc-editor.org/info/rfc2474>.
[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, , <https://www.rfc-editor.org/info/rfc2475>.
[RFC8340]
Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, , <https://www.rfc-editor.org/info/rfc8340>.

Appendix A. Company A, Company B and Company C examples

Company A, Company B and Company C Diffserv modules augments all the filter types of the QoS classifier module as well as the QoS policy module that allow it to define marking, metering, min-rate, max-rate actions. Queuing and metering counters are realized by augmenting of the QoS target module.

A.1. Example of Company A Diffserv Model

The following Company A vendor example augments the qos and diffserv model, demonstrating some of the following functionality:

- use of template based classifier definitions

- use of single policy type modelling queue, scheduler policy, and a filter policy. All of these policies either augment the qos policy or the diffserv modules

- use of inline actions in a policy

- flexibility in marking dscp or metadata at ingress and/or egress.

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

     import ietf-traffic-policy {
       prefix policy;
       reference "RFC XXXX: YANG Model for QoS";
     }
     import ietf-qos-action {
       prefix action;
       reference "RFC XXXX: YANG Model for QoS";
     }
     import ietf-diffserv {
       prefix diffserv;
       reference "RFC XXXX: YANG Model for QoS";
     }

     organization "Company A";
     contact
       "Editor:   XYZ
                 <mailto:xyz@compa.com>";
     description
       "This module contains a collection of YANG definitions of
        companyA diffserv specification extension.";
        Copyright (c) 2021 IETF Trust and the persons identified as
        authors of the code.  All rights reserved.
        Redistribution and use in source and binary forms, with or
        without modification, is permitted pursuant to, and subject
        to the license terms contained in, the Simplified BSD License
        set forth in Section 4.c of the IETF Trust's Legal Provisions
        Relating to IETF Documents
        (http://trustee.ietf.org/license-info).

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

     revision 2021-07-12 {
       description
         "Initial revision for diffserv actions on network packets";
       reference
         "RFC 6020: YANG - A Data Modeling Language for the
                    Network Configuration Protocol (NETCONF)";
     }

     identity default-policy-type {
       base policy:policy-type;
       description
         "This defines default policy-type";
     }

     identity qos-group {
       base policy:filter-type;
       description
         "qos-group filter-type";
     }

     grouping qos-group-cfg {
       list qos-group-cfg {
         key "qos-group-min qos-group-max";
         description
           "list of dscp ranges";
         leaf qos-group-min {
           type uint8;
           description
             "Minimum value of qos-group range";
         }
         leaf qos-group-max {
           type uint8;
           must ". >= ../qos-group-min" {
             error-message
             "The qos-group-max must be greater than or equal to
              qos-group-min";
           }
           description
             "maximum value of qos-group range";
         }
       }
       description
         "Filter containing list of qos-group ranges";
     }

     grouping wred-threshold {
       container wred-min-thresh {
         uses action:threshold;
         description
           "Minimum threshold";
       }
       container wred-max-thresh {
         uses action:threshold;
         description
           "Maximum threshold";
       }
       leaf mark-probability {
         type uint32 {
           range "1..1000";
         }
         description
           "Mark probability";
       }
       description
         "WRED threshold attributes";
     }

     grouping randomdetect {
       leaf exp-weighting-const {
         type uint32;
         description
           "Exponential weighting constant factor for wred profile";
       }
       uses wred-threshold;
       description
         "Random detect attributes";
     }

     augment "/policy:classifiers/" +
             "policy:classifier-entry/" +
             "policy:filter-entry/diffserv:filter-param" {
       case qos-group {
         uses qos-group-cfg;
         description
           "Filter containing list of qos-group ranges.
            Qos-group represent packet metadata information
            in a device. ";
       }
       description
         "augmentation of classifier filters";
     }
     augment "/policy:policies/policy:policy-entry/" +
             "policy:classifier-entry/" +
             "policy:classifier-action-entry-cfg/" +
             "policy:action-cfg-params" {
       case random-detect {
         uses randomdetect;
       }
       description
         "Augment the actions to policy entry";
     }

     augment "/policy:policies" +
             "/policy:policy-entry" +
             "/policy:classifier-entry" +
             "/policy:classifier-action-entry-cfg" +
             "/policy:action-cfg-params" +
             "/diffserv:meter-inline" +
             "/diffserv:meter-type" +
             "/diffserv:one-rate-two-color-meter-type" +
             "/diffserv:one-rate-two-color-meter" +
             "/diffserv:conform-action" +
             "/diffserv:conform-2color-meter-action-params" +
             "/diffserv:conform-2color-meter-action-val" {

       description
             "augment the one-rate-two-color meter conform
              with actions";
       case meter-action-drop {
         description
             "meter drop";
              uses action:drop;
       }
       case meter-action-mark-dscp {
         description
             "meter action dscp marking";
              uses action:dscp-marking;
       }
     }
     augment "/policy:policies" +
             "/policy:policy-entry" +
             "/policy:classifier-entry" +
             "/policy:classifier-action-entry-cfg" +
             "/policy:action-cfg-params" +
             "/diffserv:meter-inline" +
             "/diffserv:meter-type" +
             "/diffserv:one-rate-two-color-meter-type" +
             "/diffserv:one-rate-two-color-meter" +
             "/diffserv:exceed-action" +
             "/diffserv:exceed-2color-meter-action-params" +
             "/diffserv:exceed-2color-meter-action-val" {

       description
             "augment the one-rate-two-color meter exceed
              with actions";
       case meter-action-drop {
         description
             "meter drop";
              uses action:drop;
       }
       case meter-action-mark-dscp {
         description
             "meter action dscp marking";
              uses action:dscp-marking;
       }
     }
     augment "/policy:policies" +
             "/policy:policy-entry" +
             "/policy:classifier-entry" +
             "/policy:classifier-action-entry-cfg" +
             "/policy:action-cfg-params" +
             "/diffserv:meter-inline" +
             "/diffserv:meter-type" +
             "/diffserv:one-rate-tri-color-meter-type" +
             "/diffserv:one-rate-tri-color-meter" +
             "/diffserv:conform-action" +
             "/diffserv:conform-3color-meter-action-params" +
             "/diffserv:conform-3color-meter-action-val" {

       description
             "augment the one-rate-tri-color meter conform
              with actions";
       case meter-action-drop {
         description
             "meter drop";
              uses action:drop;
       }
       case meter-action-mark-dscp {
         description
             "meter action dscp marking";
              uses action:dscp-marking;
       }
     }
     augment "/policy:policies" +
             "/policy:policy-entry" +
             "/policy:classifier-entry" +
             "/policy:classifier-action-entry-cfg" +
             "/policy:action-cfg-params" +
             "/diffserv:meter-inline" +
             "/diffserv:meter-type" +
             "/diffserv:one-rate-tri-color-meter-type" +
             "/diffserv:one-rate-tri-color-meter" +
             "/diffserv:exceed-action" +
             "/diffserv:exceed-3color-meter-action-params" +
             "/diffserv:exceed-3color-meter-action-val" {

       description
             "augment the one-rate-tri-color meter exceed
              with actions";
       case meter-action-drop {
         description
             "meter drop";
              uses action:drop;
       }
       case meter-action-mark-dscp {
         description
             "meter action dscp marking";
              uses action:dscp-marking;
       }
     }
     augment "/policy:policies" +
             "/policy:policy-entry" +
             "/policy:classifier-entry" +
             "/policy:classifier-action-entry-cfg" +
             "/policy:action-cfg-params" +
             "/diffserv:meter-inline" +
             "/diffserv:meter-type" +
             "/diffserv:one-rate-tri-color-meter-type" +
             "/diffserv:one-rate-tri-color-meter" +
             "/diffserv:violate-action" +
             "/diffserv:violate-3color-meter-action-params" +
             "/diffserv:violate-3color-meter-action-val" {
       description
             "augment the one-rate-tri-color meter conform
              with actions";
       case meter-action-drop {
         description
             "meter drop";
              uses action:drop;
       }
       case meter-action-mark-dscp {
         description
             "meter action dscp marking";
              uses action:dscp-marking;
       }
     }

     augment "/policy:policies" +
             "/policy:policy-entry" +
             "/policy:classifier-entry" +
             "/policy:classifier-action-entry-cfg" +
             "/policy:action-cfg-params" +
             "/diffserv:meter-inline" +
             "/diffserv:meter-type" +
             "/diffserv:two-rate-tri-color-meter-type" +
             "/diffserv:two-rate-tri-color-meter" +
             "/diffserv:conform-action" +
             "/diffserv:conform-3color-meter-action-params" +
             "/diffserv:conform-3color-meter-action-val" {

       description
             "augment the one-rate-tri-color meter conform
              with actions";
       case meter-action-drop {
         description
             "meter drop";
              uses action:drop;
       }
       case meter-action-mark-dscp {
         description
             "meter action dscp marking";
              uses action:dscp-marking;
       }
     }
     augment "/policy:policies" +
             "/policy:policy-entry" +
             "/policy:classifier-entry" +
             "/policy:classifier-action-entry-cfg" +
             "/policy:action-cfg-params" +
             "/diffserv:meter-inline" +
             "/diffserv:meter-type" +
             "/diffserv:two-rate-tri-color-meter-type" +
             "/diffserv:two-rate-tri-color-meter" +
             "/diffserv:exceed-action" +
             "/diffserv:exceed-3color-meter-action-params" +
             "/diffserv:exceed-3color-meter-action-val" {

       description
             "augment the two-rate-tri-color meter exceed
              with actions";
       case meter-action-drop {
         description
             "meter drop";
              uses action:drop;
       }
       case meter-action-mark-dscp {
         description
             "meter action dscp marking";
              uses action:dscp-marking;
       }
     }
     augment "/policy:policies" +
             "/policy:policy-entry" +
             "/policy:classifier-entry" +
             "/policy:classifier-action-entry-cfg" +
             "/policy:action-cfg-params" +
             "/diffserv:meter-inline" +
             "/diffserv:meter-type" +
             "/diffserv:two-rate-tri-color-meter-type" +
             "/diffserv:two-rate-tri-color-meter" +
             "/diffserv:violate-action" +
             "/diffserv:violate-3color-meter-action-params" +
             "/diffserv:violate-3color-meter-action-val" {
       description
             "augment the two-rate-tri-color meter violate
              with actions";
       case meter-action-drop {
         description
             "meter drop";
              uses action:drop;
       }
       case meter-action-mark-dscp {
         description
             "meter action dscp marking";
              uses action:dscp-marking;
       }
     }
     augment "/policy:policies" +
             "/policy:policy-entry" +
             "/policy:classifier-entry" +
             "/policy:classifier-action-entry-cfg" +
             "/policy:action-cfg-params" +
             "/diffserv:meter-inline" +
             "/diffserv:meter-type" +
             "/diffserv:one-rate-two-color-meter-type" +
             "/diffserv:one-rate-two-color-meter" {
       description
             "augment the one-rate-two-color meter with" +
             "color classifiers";
         container conform-color {
           uses classifier:classifier-entry-generic-attr;
           description
             "conform color classifier container";
         }
         container exceed-color {
           uses classifier:classifier-entry-generic-attr;
           description
             "exceed color classifier container";
         }
     }
     augment "/policy:policies" +
             "/policy:policy-entry" +
             "/policy:classifier-entry" +
             "/policy:classifier-action-entry-cfg" +
             "/policy:action-cfg-params" +
             "/diffserv:meter-inline" +
             "/diffserv:meter-type" +
             "/diffserv:one-rate-tri-color-meter-type" +
             "/diffserv:one-rate-tri-color-meter" {
       description
             "augment the one-rate-tri-color meter with" +
             "color classifiers";
         container conform-color {
           uses classifier:classifier-entry-generic-attr;
           description
             "conform color classifier container";
         }
         container exceed-color {
           uses classifier:classifier-entry-generic-attr;
           description
             "exceed color classifier container";
         }
         container violate-color {
           uses policy:classifier-entry-generic-attr;
           description
             "violate color classifier container";
         }
     }
     augment "/policy:policies" +
             "/policy:policy-entry" +
             "/policy:classifier-entry" +
             "/policy:classifier-action-entry-cfg" +
             "/policy:action-cfg-params" +
             "/diffserv:meter-inline" +
             "/diffserv:meter-type" +
             "/diffserv:two-rate-tri-color-meter-type" +
             "/diffserv:two-rate-tri-color-meter" {
       description
             "augment the two-rate-tri-color meter with" +
             "color classifiers";
         container conform-color {
           uses classifier:classifier-entry-generic-attr;
           description
             "conform color classifier container";
         }
         container exceed-color {
           uses policy:classifier-entry-generic-attr;
           description
             "exceed color classifier container";
         }
         container violate-color {
           uses policy:classifier-entry-generic-attr;
           description
             "violate color classifier container";
         }
     }
   }

A.2. Example of Company B Diffserv Model

The following vendor example augments the qos and diffserv model, demonstrating some of the following functionality:

- use of inline classifier definitions (defined inline in the policy vs referencing an externally defined classifier)

- use of mulitple policy types, e.g. a queue policy, a scheduler policy, and a filter policy. All of these policies either augment the qos policy or the diffserv modules

- use of a queue module, which uses and extends the queue grouping from the ietf-qos-action module

- use of meter templates (v.s. meter inline)

- use of internal meta data for classification and marking

module example-compb-diffserv-filter-policy {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:" +
               "example-compb-diffserv-filter-policy";
     prefix compb-filter-policy;

  import ietf-traffic-policy {
    prefix policy;
    reference "RFC XXXX: YANG Model for QoS";
  }
  import ietf-qos-action {
    prefix action;
    reference "RFC XXXX: YANG Model for QoS";
  }
  import ietf-diffserv {
    prefix diffserv;
    reference "RFC XXXX: YANG Model for QoS";
  }

  organization "Company B";
  contact
    "Editor:   XYZ
              <mailto:xyz@compb.com>";

  description
    "This module contains a collection of YANG definitions for
     configuring diffserv specification implementations.
     Copyright (c) 2021 IETF Trust and the persons identified as
     authors of the code.  All rights reserved.
     Redistribution and use in source and binary forms, with or
     without modification, is permitted pursuant to, and subject
     to the license terms contained in, the Simplified BSD License
     set forth in Section 4.c of the IETF Trust's Legal Provisions
     Relating to IETF Documents
     (http://trustee.ietf.org/license-info).

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

  revision 2021-07-12 {
    description
      "Initial revision of Company B diffserv policy";
    reference "RFC XXXX";
  }


  /*************************************************
   * Classification types
   *************************************************/

  identity forwarding-class {
      base policy:filter-type;
      description
        "Forwarding class filter type";
  }

  identity internal-loss-priority  {
     base policy:filter-type;
     description
        "Internal loss priority filter type";
  }

  grouping forwarding-class-cfg {
    list forwarding-class-cfg {
      key "forwarding-class";
      description
        "list of forwarding-classes";
      leaf forwarding-class {
        type string;
        description
          "Forwarding class name";
      }
    }
    description
      "Filter containing list of forwarding classes";
  }

  grouping loss-priority-cfg {
    list loss-priority-cfg {
      key "loss-priority";
      description
        "list of loss-priorities";
      leaf loss-priority {
        type enumeration {
          enum high {
           description "High Loss Priority";
          }
          enum medium-high {
           description "Medium-high Loss Priority";
          }
          enum medium-low {
           description "Medium-low Loss Priority";
          }
          enum low {
           description "Low Loss Priority";
          }
        }
        description
          "Loss-priority";
      }
    }
    description
      "Filter containing list of loss priorities";
  }

  augment "/policy:policies" +
          "/policy:policy-entry" +
          "/policy:classifier-entry" +
          "/policy:filter-entry" +
          "/diffserv:filter-params" {
    case forwarding-class {
        uses forwarding-class-cfg;
      description
        "Filter Type Internal-loss-priority";
    }
    case internal-loss-priority {
        uses loss-priority-cfg;
      description
        "Filter Type Internal-loss-priority";
    }
    description
      "Augments Diffserv Classifier with vendor" +
      " specific types";
  }

  /*************************************************
   * Actions
   *************************************************/

  identity mark-fwd-class {
    base policy:action-type;
    description
      "mark forwarding class action type";
  }

  identity mark-loss-priority {
    base policy:action-type;
    description
      "mark loss-priority action type";
  }

  grouping mark-fwd-class {
    container mark-fwd-class-cfg {
      leaf forwarding-class {
        type string;
        description
          "Forwarding class name";
      }
      description
        "mark-fwd-class container";
    }
    description
      "mark-fwd-class grouping";
  }

  grouping mark-loss-priority {
    container mark-loss-priority-cfg {
      leaf loss-priority {
        type enumeration {
          enum high {
           description "High Loss Priority";
          }
          enum medium-high {
           description "Medium-high Loss Priority";
          }
          enum medium-low {
           description "Medium-low Loss Priority";
          }
          enum low {
           description "Low Loss Priority";
          }
        }
        description
          "Loss-priority";
      }
      description
        "mark-loss-priority container";
    }
    description
      "mark-loss-priority grouping";
  }

  identity exceed-2color-meter-action-drop {
    base action:exceed-2color-meter-action-type;
    description
      "drop action type in a meter";
  }

  identity meter-action-mark-fwd-class {
    base action:exceed-2color-meter-action-type;
    description
      "mark forwarding class action type";
  }

  identity meter-action-mark-loss-priority {
    base action:exceed-2color-meter-action-type;
    description
      "mark loss-priority action type";
  }

  identity violate-3color-meter-action-drop {
    base action:violate-3color-meter-action-type;
    description
      "drop action type in a meter";
  }

  augment "/policy:policies/policy:policy-entry/" +
             "policy:classifier-entry/" +
             "policy:classifier-action-entry-cfg/" +
             "policy:action-cfg-params" {
    case mark-fwd-class {
      uses mark-fwd-class;
      description
        "Mark forwarding class in the packet";
    }
    case mark-loss-priority {
        uses mark-loss-priority;
      description
        "Mark loss priority in the packet";
    }
    case discard {
        uses action:discard;
      description
        "Discard action";
    }
    description
      "Augments common diffserv policy actions";
    }


  augment "/action:meter-template" +
          "/action:meter-entry" +
          "/action:meter-type" +
          "/action:one-rate-tri-color-meter-type" +
          "/action:one-rate-tri-color-meter" {
     leaf one-rate-color-aware {
      type boolean;
      description
        "This defines if the meter is color-aware";
    }
  }
  augment "/action:meter-template" +
          "/action:meter-entry" +
          "/action:meter-type" +
          "/action:two-rate-tri-color-meter-type" +
          "/action:two-rate-tri-color-meter" {
     leaf two-rate-color-aware {
      type boolean;
      description
        "This defines if the meter is color-aware";
    }
  }

  /* example of augmenting a meter template with a
  /* vendor specific action */
  augment "/action:meter-template" +
          "/action:meter-entry" +
          "/action:meter-type" +
          "/action:one-rate-two-color-meter-type" +
          "/action:one-rate-two-color-meter" +
          "/action:exceed-action" +
          "/action:exceed-2color-meter-action-params" +
          "/action:exceed-2color-meter-action-val" {

    case exceed-2color-meter-action-drop {
      description
          "meter drop";
           uses action:drop;
    }
    case meter-action-mark-fwd-class {
      uses mark-fwd-class;
      description
        "Mark forwarding class in the packet";
    }
    case meter-action-mark-loss-priority {
        uses mark-loss-priority;
      description
        "Mark loss priority in the packet";
    }
  }

  augment "/action:meter-template" +
          "/action:meter-entry" +
          "/action:meter-type" +
          "/action:two-rate-tri-color-meter-type" +
          "/action:two-rate-tri-color-meter" +
          "/action:violate-action" +
          "/action:violate-3color-meter-action-params" +
          "/action:violate-3color-meter-action-val" {
    case exceed-3color-meter-action-drop {
      description
          "meter drop";
      uses action:drop;
    }

    description
      "Augment the actions to the two-color meter";
  }

  augment "/action:meter-template" +
          "/action:meter-entry" +
          "/action:meter-type" +
          "/action:one-rate-tri-color-meter-type" +
          "/action:one-rate-tri-color-meter" +
          "/action:violate-action" +
          "/action:violate-3color-meter-action-params" +
          "/action:violate-3color-meter-action-val" {
    case exceed-3color-meter-action-drop {
      description
          "meter drop";
      uses action:drop;
    }

    description
      "Augment the actions to basic meter";
  }

}
module example-compb-queue-policy {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:example-compb-queue-policy";
  prefix queue-plcy;

  import ietf-traffic-policy {
    prefix policy;
    reference "RFC XXXX: YANG Model for QoS";
  }

  organization "Company B";
  contact
    "Editor:   XYZ
              <mailto:xyz@compb.com>";

  description
    "This module defines a queue policy. The classification
     is based on aforwarding class, and the actions are queues.
     Copyright (c) 2021 IETF Trust and the persons identified as
     authors of the code.  All rights reserved.
     Redistribution and use in source and binary forms, with or
     without modification, is permitted pursuant to, and subject
     to the license terms contained in, the Simplified BSD License
     set forth in Section 4.c of the IETF Trust's Legal Provisions
     Relating to IETF Documents
     (http://trustee.ietf.org/license-info).
     This version of this YANG module is part of RFC XXXX; see
     the RFC itself for full legal notices.";

  revision 2021-07-12 {
    description
      "Latest revision of Company B queue policy";
    reference "RFC XXXX";
  }

  identity forwarding-class {
    base policy:filter-type;
    description
       "Forwarding class filter type";
  }

  grouping forwarding-class-cfg {
    leaf forwarding-class-cfg {
      type string;
      description
        "forwarding-class name";
    }
    description
      "Forwarding class filter";
  }

  augment "/policy:policies" +
          "/policy:policy-entry" +
          "/policy:classifier-entry" +
          "/policy:filter-entry" {
    /* Does NOT support "logical-not" of forwarding class.
       Use "must"? */
    choice filter-params {
      description
        "Choice of filters";
      case forwarding-class-cfg {
        uses forwarding-class-cfg;
        description
          "Filter Type Internal-loss-priority";
      }
    }
    description
      "Augments Diffserv Classifier with fwd class filter";
  }

  identity compb-queue {
    base policy:action-type;
    description
      "compb-queue action type";
  }

  grouping compb-queue-name {
    container queue-name {
      leaf name {
        type string;
        description
          "Queue class name";
      }
      description
        "compb queue container";
    }
    description
      "compb-queue grouping";
  }

  augment "/policy:policies" +
          "/policy:policy-entry" +
          "/policy:classifier-entry" +
          "/policy:classifier-action-entry-cfg" {
    choice action-cfg-params {
      description
        "Choice of action types";
      case compb-queue {
        uses compb-queue-name;
      }
    }
    description
      "Augment the queue actions to queue policy entry";
  }
}

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

  import ietf-qos-action {
    prefix action;
    reference "RFC XXXX: YANG Model for QoS";
  }

  organization "Company B";
  contact
    "Editor:   XYZ
              <mailto:xyz@compb.com>";

  description
    "This module describes a compb queue module. This is a
     template for a queue within a queue policy, referenced
     by name.

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

  revision 2021-07-12 {
    description
      "Latest revision of diffserv based classifier";
    reference "RFC XXXX";
  }

  container compb-queue {
    description
      "Queue used in compb architecture";
      leaf name {
          type string;
          description
            "A unique name identifying this queue";
      }
      uses action:queue;
      container excess-rate {
        choice excess-rate-type {
           case percent {
             leaf excess-rate-percent {
               type uint32 {
                 range "1..100";
               }
               description
                 "excess-rate-percent";
             }
           }
           case proportion {
             leaf excess-rate-poroportion {
               type uint32 {
                 range "1..1000";
               }
               description
                 "excess-rate-poroportion";
             }
           }
           description
             "Choice of excess-rate type";
        }
        description
            "Excess rate value";
      }
      leaf excess-priority {
        type enumeration {
          enum high {
           description "High Loss Priority";
          }
          enum medium-high {
           description "Medium-high Loss Priority";
          }
          enum medium-low {
           description "Medium-low Loss Priority";
          }
          enum low {
           description "Low Loss Priority";
          }
          enum none {
           description "No excess priority";
          }
        }
        description
          "Priority of excess (above guaranted rate) traffic";
      }
      container buffer-size {
        choice buffer-size-type {
           case percent {
             leaf buffer-size-percent {
               type uint32 {
                 range "1..100";
               }
               description
                 "buffer-size-percent";
             }
           }
           case temporal {
             leaf buffer-size-temporal {
               type uint64;
               units "microsecond";
               description
                 "buffer-size-temporal";
             }
           }
           case remainder {
             leaf buffer-size-remainder {
               type empty;
               description
                 "use remaining of buffer";
             }
           }
           description
             "Choice of buffer size type";
        }
        description
            "Buffer size value";
      }
  }

  augment
    "/compb-queue" +
    "/queue-cfg" +
    "/algorithmic-drop-cfg" +
    "/drop-algorithm" {
    case random-detect {
      list drop-profile-list {
        key "priority";
        description
          "map of priorities to drop-algorithms";
        leaf priority {
          type enumeration {
            enum any {
              description "Any priority mapped here";
            }
            enum high {
              description "High Priority Packet";
            }
            enum medium-high {
              description "Medium-high Priority Packet";
            }
            enum medium-low {
              description "Medium-low Priority Packet";
            }
            enum low {
              description "Low Priority Packet";
            }
          }
          description
            "Priority of guaranteed traffic";
        }
        leaf drop-profile {
          type string;
          description
            "drop profile to use for this priority";
        }
      }
    }
    description
      "compb random detect drop algorithm config";
  }
}

module example-compb-scheduler-policy {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:" +
               "example-compb-scheduler-policy";
     prefix scheduler-plcy;

  import ietf-qos-action {
    prefix action;
    reference "RFC XXXX: YANG Model for QoS";
  }

  import ietf-traffic-policy {
    prefix policy;
    reference "RFC XXXX: YANG Model for QoS";
  }

  organization "Company B";
  contact
    "Editor:   XYZ
              <mailto:xyz@compb.com>";

   description
     "This module defines a scheduler policy. The classification
      is based on classifier-any, and the action is a scheduler.";

   revision 2021-07-12 {
     description
       "Initial revision of Company B Scheduler policy";
     reference "RFC XXXX";
   }

   identity queue-policy {
     base policy:action-type;
     description
       "forwarding-class-queue action type";
   }

  grouping queue-policy-name {
    container compb-queue-policy-name {
      leaf name {
        type string;
        description
          "Queue policy name";
      }
      description
        "compb-queue-policy container";
    }
    description
      "compb-queue policy grouping";
  }

  augment "/policy:policies" +
          "/policy:policy-entry" +
          "/policy:classifier-entry" +
          "/policy:classifier-action-entry-cfg" {
    choice action-cfg-params {
      case schedular {
        uses action:schedular;
      }
      case queue-policy {
        uses queue-policy-name;
      }
      description
        "Augment the scheduler policy with a queue policy";
    }
  }
}

A.3. Example of Company C Diffserv Model

Company C vendor augmentation is based on Ericsson's implementation differentiated QoS. This implementation first sorts traffic based on a classifier, which can sort traffic into one or more traffic forwarding classes. Then, a policer or meter policy references the classifier and its traffic forwarding classes to specify different service levels for each traffic forwarding class.

Because each classifier sorts traffic into one or more traffic forwarding classes, this type of classifier does not align with ietf-qos-classifier.yang, which defines one traffic forwarding class per classifier. Additionally, Company C's policing and metering policies relies on the classifier's pre-defined traffic forwarding classes to provide differentiated services, rather than redefining the patterns within a policing or metering policy, as is defined in ietf-diffserv.yang.

Due to these differences, even though Company C uses all the building blocks of classifier and policy, Company C's augmentation does not use ietf-diffserv.yang to provide differentiated service levels. Instead, Company C's augmentation uses the basic building blocks, ietf-traffic-policy.yang to provide differentiated services.

module example-compc-qos-policy {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:example-compc-qos-policy";
  prefix "compcqos";

  import ietf-traffic-policy {
    prefix "pol";
    reference "RFC XXXX: YANG Model for QoS";
  }

  import ietf-qos-action {
    prefix "action";
    reference "RFC XXXX: YANG Model for QoS";
  }

  organization "Company C";
  contact "Company C Editor: XYZ <mailto:xyz@compc.com>";
  description
    "This module contains a collection of YANG definitions for
     configuring diffserv specification implementations.
     Copyright (c) 2021 IETF Trust and the persons identified as
     authors of the code.  All rights reserved.
     Redistribution and use in source and binary forms, with or
     without modification, is permitted pursuant to, and subject
     to the license terms contained in, the Simplified BSD License
     set forth in Section 4.c of the IETF Trust's Legal Provisions
     Relating to IETF Documents
     (http://trustee.ietf.org/license-info).

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

  revision 2021-07-12 {
    description "Initial version";
    reference "RFC XXXX";
  }

  /* identities */

  identity compc-qos-policy {
    base pol:policy-type;
    description "compc-specific policy base type";
  }

  identity mdrr-queuing-policy {
    base compc-qos-policy;
    description "compc-specific MDRR policy type";
  }

  identity pwfq-queuing-policy {
    base compc-qos-policy;
    description "compc-specific queuing policy type";
  }

  identity policing-policy {
    base compc-qos-policy;
    description "compc-specific policing policy type";
  }

  identity metering-policy {
    base compc-qos-policy;
    description "compc-specific metering policy type";
  }

  identity forwarding-policy {
    base compc-qos-policy;
    description "compc-specific forwarding policy type";
  }

  identity overhead-profile-policy {
    base compc-qos-policy;
    description "compc-specific overhead profile policy type";
  }

  identity resource-profile-policy {
    base compc-qos-policy;
    description "compc-specific resource profile policy type";
  }

  identity protocol-rate-limit-policy {
    base compc-qos-policy;
    description "compc-specific protocol rate limit policy type";
  }

  identity compc-qos-action {
    base pol:action-type;
    description "compc-specificc qos action base type";
  }

  /* groupings */

  grouping redirect-action-grp {
    description "Redirection options grouping";
    container redirect {
      description "Redirect options";
    }
  }

  /* deviations */

  deviation "/pol:policies/pol:policy-entry" {
    deviate add {
      must "pol:type = compc-qos-policy" {
        description
          "Only policy types drived from compc-qos-policy " +
          "are supported";
      }
    }
  }

  deviation "/pol:policies/pol:policy-entry/pol:classifier-entry" {
    deviate add {
      must "../per-class-action = 'true'" {
        description
          "Only policies with per-class actions have classifiers";
      }
      must "((../compcqos:sub-type != " +
                           "'compcqos:mdrr-queuing-policy') and " +
           " (../compcqos:sub-type != " +
                           "'compcqos:pwfq-queuing-policy')) or " +
           "(((../compcqos:sub-type = " +
                           "'compcqos:mdrr-queuing-policy') or " +
           "  (../compcqos:sub-type = " +
                           "'compcqos:pwfq-queueing-policy')) and " +
           " ((classifier-entry-name = '0') or " +
           "  (classifier-entry-name = '1') or " +
           "  (classifier-entry-name = '2') or " +
           "  (classifier-entry-name = '3') or " +
           "  (classifier-entry-name = '4') or " +
           "  (classifier-entry-name = '5') or " +
           "  (classifier-entry-name = '6') or " +
           "  (classifier-entry-name = '7') or " +
           "  (classifier-entry-name = '8')))" {
        description
          "MDRR queuing policy's or PWFQ queuing policy's " +
          "classifier-entry-name is limited to the listed values";
      }
    }
  }

  deviation "/pol:policies/pol:policy-entry/pol:classifier-entry" +
            "/pol:classifier-action-entry-cfg" {
    deviate add {
      must "action-type = 'compcqos:compc-qos-action'" {
        description
          "Only compc-qos-action is allowed";
      }
      max-elements 1;
    }
  }

  /* augments */

  augment "/pol:policies/pol:policy-entry" {
    when "pol:policy-type = 'compc-qos-policy'" {
      description
        "Additional nodes only for diffserv-policy";
    }
    description "Additional diffserv-policy nodes";
    leaf sub-type {
      type identityref {
        base compc-qos-policy;
      }
      mandatory true;
      description "Policy sub-type. The value of this leaf must " +
                  "not change once configured";
    }
    leaf per-class-action {
      type boolean;
      must "(((. = 'true') and " +
           "  ((../compcqos:sub-type = " +
                              "'compcqos:policing-policy') or " +
           "   (../compcqos:sub-type = " +
                              "'compcqos:metering-policy') or " +
           "   (../compcqos:sub-type = " +
                              "'compcqos:mdrr-queuing-policy') or " +
           "   (../compcqos:sub-type = " +
                              "'compcqos:pwfq-queuing-policy') or " +
           "   (../compcqos:sub-type = " +
                              "'compcqos:forwarding-policy'))) or " +
           " ((. = 'false') and " +
           "  ((../compcqos:sub-type = " +
                        "'compcqos:overhead-profile-policy') or " +
           "   (../compcqos:sub-type = " +
                        "'compcqos:resource-profile-policy') or " +
           "   (../compcqos:sub-type = " +
                        "'compcqos:protocol-rate-limit-policy'))))" {
        description
          "Only certain policies have per-class action";
      }
      mandatory true;
      description "Per-class action";
    }
    container traffic-classifier {
      when "../compcqos:sub-type = 'compcqos:policing-policy' or " +
           "../compcqos:sub-type = 'compcqos:metering-policy' or " +
           "../compcqos:sub-type = 'compcqos:forwarding-policy'" {
        description
          "A classifier for policing-policy or metering-policy";
      }
      presence true;
      leaf name {
        type string;
        mandatory true;
        description
          "Traffic classifier name";
      }
      leaf type {
        type enumeration {
          enum 'internal-dscp-only-classifier' {
            value 0;
            description
              "Classify traffic based on (internal) dscp only";
          }
          enum 'ipv4-header-based-classifier' {
            value 1;
            description
              "Classify traffic based on IPv4 packet header fields";
          }
          enum 'ipv6-header-based-classifier' {
            value 2;
            description
              "Classify traffic based on IPv6 packet header fields";
          }
        }
        mandatory true;
        description
          "Traffic classifier type";
      }
      description "Traffic classifier";
    }
    container traffic-queue {
      when "(../compcqos:sub-type = " +
                             "'compcqos:mdrr-queuing-policy') or " +
           "(../compcqos:sub-type = " +
                             "'compcqos:pwfq-queuing-policy')" {
        description
          "Queuing policy properties";
      }
      leaf queue-map {
        type string;
        description
          "Traffic queue map for queuing policy";
      }
      description "Traffic queue";
    }
    container overhead-profile {
      when "../compcqos:sub-type = " +
                             "'compcqos:overhead-profile-policy'" {
        description
          "Overhead profile policy properties";
      }
      description "Overhead profile";
    }
    container resource-profile {
      when "../compcqos:sub-type = " +
                             "'compcqos:resource-profile-policy'" {
        description
          "Resource profile policy properties";
      }
      description "Resource profile";
    }
    container protocol-rate-limit {
      when "../compcqos:sub-type = " +
                           "'compcqos:protocol-rate-limit-policy'" {
        description
          "Protocol rate limit policy properties";
      }
      description "Protocol rate limit";
    }
  }

  augment "/pol:policies/pol:policy-entry/pol:classifier-entry" +
          "/pol:classifier-action-entry-cfg/pol:action-cfg-params" {
    when "../../pol:policy-type = 'compc-qos-policy'" {
      description
        "Configurations for a classifier-policy-type policy";
    }
    case metering-or-policing-policy {
      when "../../compcqos:sub-type = " +
                                 "'compcqos:policing-policy' or " +
           "../../compcqos:sub-type = 'compcqos:metering-policy'" {
      }
      container dscp-marking {
        uses action:dscp-marking;
        description "DSCP marking";
      }
      container precedence-marking {
        uses action:dscp-marking;
        description "Precedence marking";
      }
      container priority-marking {
        uses action:priority;
        description "Priority marking";
      }
      container rate-limiting {
        uses action:one-rate-two-color-meter;
        description "Rate limiting";
      }
    }
    case mdrr-queuing-policy {
      when "../../compcqos:sub-type = " +
                                 "'compcqos:mdrr-queuing-policy'" {
        description
          "MDRR queue handling properties for the traffic " +
          "classified into current queue";
      }
      leaf mdrr-queue-weight {
        type uint8 {
          range "20..100";
        }
        units percentage;
        description "MDRR queue weight";
      }
    }
    case pwfq-queuing-policy {
      when "../../compcqos:sub-type = " +
                                  "'compcqos:pwfq-queuing-policy'" {
        description
          "PWFQ queue handling properties for traffic " +
          "classified into current queue";
      }
      leaf pwfq-queue-weight {
        type uint8 {
          range "20..100";
        }
        units percentage;
        description "Priority-based weighted fair queue weight";
      }
      leaf pwfq-queue-priority {
        type uint8;
        description "Priority-based weighted fair queue priority";
      }
      leaf pwfq-queue-rate {
        type uint8;
        description "Priority-based weighted fair queue rate";
      }
    }
    case forwarding-policy {
      when "../../compcqos:sub-type = 'compcqos:forwarding-policy'" {
        description
          "Forward policy handling properties for traffic " +
          "in this classifier";
      }
      uses redirect-action-grp;
    }
    description
      "Add the classify action configuration";
  }
}

A.4. Configuration example for QoS Classifier 

<!--
    This example shows a QoS classifier configuration.
-->

<?xml version="1.0" encoding="UTF-8"?>
<classifiers
    xmlns="urn:ietf:params:xml:ns:yang:ietf-traffic-policy"
      xmlns:bt="urn:ietf:params:xml:ns:yang:ietf-bgp-types">
  <classifier>
    <name>my-classifier</name>
    <filter-operation>match-any-filter</filter-operation>
    <filter>
      <type>dscp</type>
      <logical-not>true</logical-not>
    </filter>
  </classifier>
</classifiers>
Figure 13: Configuration example for QoS Classifier

A.5. Configuration example for QoS Policy 

<!--
    This example shows a QoS policy configuration.
-->

<?xml version="1.0" encoding="UTF-8"?>
<policies
  xmlns="urn:ietf:params:xml:ns:yang:ietf-traffic-policy">
  <policy>
    <name>my-policy</name>
    <type>diffserv</type>
    <classifier>
      <name>my-classifier</name>
      <inline>true</inline>
      <filter-operation>match-any-filter</filter-operation>
      <filter>
        <type>dscp</type>
        <logical-not>true</logical-not>
      </filter>
      <action>
        <type>dscp-marking</type>
        <!--
             Add the action-params here once it has been defined.
        -->
      </action>
    </classifier>
  </policy>
</policies>
Figure 14: Configuration example for QoS Policy

Authors' Addresses

Aseem Choudhary
Aviatrix Systems
2901 Tasman Drive #109
Santa Clara, CA 95054
United States of America
Mahesh Jethanandani
Kloud Services
Ebben Aries
Juniper Networks
1194 North Mathilda Avenue
Sunnyvale, CA 94089
United States of America
Ing-Wher Chen
The MITRE Corporation