An Informal Management Model for Diffserv Routers
RFC 3290

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Network Working Group                                          Y. Bernet
Request for Comments: 3290                                     Microsoft
Category: Informational                                         S. Blake
                                                                Ericsson
                                                             D. Grossman
                                                                Motorola
                                                                A. Smith
                                                        Harbour Networks
                                                                May 2002

           An Informal Management Model for Diffserv Routers

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2002).  All Rights Reserved.

Abstract

   This document proposes an informal management model of Differentiated
   Services (Diffserv) routers for use in their management and
   configuration.  This model defines functional datapath elements
   (e.g., classifiers, meters, actions, marking, absolute dropping,
   counting, multiplexing), algorithmic droppers, queues and schedulers.
   It describes possible configuration parameters for these elements and
   how they might be interconnected to realize the range of traffic
   conditioning and per-hop behavior (PHB) functionalities described in
   the Diffserv Architecture.

Table of Contents

   1 Introduction .................................................    3
   2 Glossary .....................................................    4
   3 Conceptual Model .............................................    7
   3.1 Components of a Diffserv Router ............................    7
   3.1.1 Datapath .................................................    7
   3.1.2 Configuration and Management Interface ...................    9
   3.1.3 Optional QoS Agent Module ................................   10
   3.2 Diffserv Functions at Ingress and Egress ...................   10
   3.3 Shaping and Policing .......................................   12
   3.4 Hierarchical View of the Model .............................   12
   4 Classifiers ..................................................   13

Bernet, et. al.              Informational                      [Page 1]
RFC 3290           Diffserv Informal Management Model           May 2002

   4.1 Definition .................................................   13
   4.1.1 Filters ..................................................   15
   4.1.2 Overlapping Filters ......................................   15
   4.2 Examples ...................................................   16
   4.2.1 Behavior Aggregate (BA) Classifier .......................   16
   4.2.2 Multi-Field (MF) Classifier ..............................   17
   4.2.3 Free-form Classifier .....................................   17
   4.2.4 Other Possible Classifiers ...............................   18
   5 Meters .......................................................   19
   5.1 Examples ...................................................   20
   5.1.1 Average Rate Meter .......................................   20
   5.1.2 Exponential Weighted Moving Average (EWMA) Meter .........   21
   5.1.3 Two-Parameter Token Bucket Meter .........................   21
   5.1.4 Multi-Stage Token Bucket Meter ...........................   22
   5.1.5 Null Meter ...............................................   23
   6 Action Elements ..............................................   23
   6.1 DSCP Marker ................................................   24
   6.2 Absolute Dropper ...........................................   24
   6.3 Multiplexor ................................................   25
   6.4 Counter ....................................................   25
   6.5 Null Action ................................................   25
   7 Queuing Elements .............................................   25
   7.1 Queuing Model ..............................................   26
   7.1.1 FIFO Queue ...............................................   27
   7.1.2 Scheduler ................................................   28
   7.1.3 Algorithmic Dropper ......................................   30
   7.2 Sharing load among traffic streams using queuing ...........   33
   7.2.1 Load Sharing .............................................   34
   7.2.2 Traffic Priority .........................................   35
   8 Traffic Conditioning Blocks (TCBs) ...........................   35
   8.1 TCB ........................................................   36
   8.1.1 Building blocks for Queuing ..............................   37
   8.2 An Example TCB .............................................   37
   8.3 An Example TCB to Support Multiple Customers ...............   42