Information Model for Describing Network Device QoS Datapath Mechanisms
RFC 3670

Document Type RFC - Proposed Standard (January 2004; No errata)
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Network Working Group                                           B. Moore
Request for Comments: 3670                               IBM Corporation
Category: Standards Track                                      D. Durham
                                                                   Intel
                                                            J. Strassner
                                                        INTELLIDEN, Inc.
                                                           A. Westerinen
                                                           Cisco Systems
                                                                W. Weiss
                                                                Ellacoya
                                                            January 2004

                   Information Model for Describing
                Network Device QoS Datapath Mechanisms

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2004).  All Rights Reserved.

Abstract

   The purpose of this document is to define an information model to
   describe the quality of service (QoS) mechanisms inherent in
   different network devices, including hosts.  Broadly speaking, these
   mechanisms describe the properties common to selecting and
   conditioning traffic through the forwarding path (datapath) of a
   network device.  This selection and conditioning of traffic in the
   datapath spans both major QoS architectures: Differentiated Services
   and Integrated Services.

   This document should be used with the QoS Policy Information Model
   (QPIM) to model how policies can be defined to manage and configure
   the QoS mechanisms (i.e., the classification, marking, metering,
   dropping, queuing, and scheduling functionality) of devices.
   Together, these two documents describe how to write QoS policy rules
   to configure and manage the QoS mechanisms present in the datapaths
   of devices.

Moore, et al.               Standards Track                     [Page 1]
RFC 3670             QoS Device Datapath Info Model         January 2004

   This document, as well as QPIM, are information models.  That is,
   they represent information independent of a binding to a specific
   type of repository.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
       1.1.  Policy Management Conceptual Model . . . . . . . . . . .  6
       1.2.  Purpose and Relation to Other Policy Work. . . . . . . .  7
       1.3.  Typical Examples of Policy Usage . . . . . . . . . . . .  7
   2.  Approach . . . . . . . . . . . . . . . . . . . . . . . . . . .  8
       2.1.  Common Needs Of DiffServ and IntServ . . . . . . . . . .  8
       2.2.  Specific Needs Of DiffServ . . . . . . . . . . . . . . .  9
       2.3.  Specific Needs Of IntServ. . . . . . . . . . . . . . . .  9
   3.  Methodology. . . . . . . . . . . . . . . . . . . . . . . . . . 10
       3.1.  Level of Abstraction for Expressing QoS Policies . . . . 10
       3.2.  Specifying Policy Parameters . . . . . . . . . . . . . . 11
       3.3.  Specifying Policy Services . . . . . . . . . . . . . . . 12
       3.4.  Level of Abstraction for Defining QoS Attributes and
             Classes. . . . . . . . . . . . . . . . . . . . . . . . . 13
       3.5.  Characterization of QoS Properties . . . . . . . . . . . 14
       3.6.  QoS Information Model Derivation . . . . . . . . . . . . 15
       3.7.  Attribute Representation . . . . . . . . . . . . . . . . 16
       3.8.  Mental Model . . . . . . . . . . . . . . . . . . . . . . 17
             3.8.1.  The QoSService Class . . . . . . . . . . . . . . 17
             3.8.2.  The ConditioningService Class. . . . . . . . . . 18
             3.8.3.  Preserving QoS Information from Ingress to
                     Egress . . . . . . . . . . . . . . . . . . . . . 19
       3.9.  Classifiers, FilterLists, and Filter Entries . . . . . . 21
       3.10. Modeling of Droppers . . . . . . . . . . . . . . . . . . 23
             3.10.1. Configuring Head and Tail Droppers . . . . . . . 23
             3.10.2. Configuring RED Droppers . . . . . . . . . . . . 24
       3.11. Modeling of Queues and Schedulers. . . . . . . . . . . . 25
             3.11.1. Simple Hierarchical Scheduler. . . . . . . . . . 25
             3.11.2. Complex Hierarchical Scheduler . . . . . . . . . 27
             3.11.3. Excess Capacity Scheduler. . . . . . . . . . . . 29
             3.11.4. Hierarchical CBQ Scheduler . . . . . . . . . . . 31
   4.  The Class Hierarchy. . . . . . . . . . . . . . . . . . . . . . 33
       4.1.  Associations and Aggregations. . . . . . . . . . . . . . 33
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