Configuration Guidelines for DiffServ Service Classes
RFC 4594

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Network Working Group                                         J. Babiarz
Request for Comments: 4594                                       K. Chan
Category: Informational                                  Nortel Networks
                                                                F. Baker
                                                           Cisco Systems
                                                             August 2006

         Configuration Guidelines for DiffServ Service Classes

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 (2006).

Abstract

   This document describes service classes configured with Diffserv and
   recommends how they can be used and how to construct them using
   Differentiated Services Code Points (DSCPs), traffic conditioners,
   Per-Hop Behaviors (PHBs), and Active Queue Management (AQM)
   mechanisms.  There is no intrinsic requirement that particular DSCPs,
   traffic conditioners, PHBs, and AQM be used for a certain service
   class, but as a policy and for interoperability it is useful to apply
   them consistently.

Babiarz, et al.              Informational                      [Page 1]
RFC 4594        Guidelines for DiffServ Service Classes      August 2006

Table of Contents

   1. Introduction ....................................................3
      1.1. Requirements Notation ......................................4
      1.2. Expected Use in the Network ................................4
      1.3. Service Class Definition ...................................5
      1.4. Key Differentiated Services Concepts .......................5
           1.4.1. Queuing .............................................6
                  1.4.1.1. Priority Queuing ...........................6
                  1.4.1.2. Rate Queuing ...............................6
           1.4.2. Active Queue Management .............................7
           1.4.3. Traffic Conditioning ................................7
           1.4.4. Differentiated Services Code Point (DSCP) ...........8
           1.4.5. Per-Hop Behavior (PHB) ..............................8
      1.5. Key Service Concepts .......................................8
           1.5.1. Default Forwarding (DF) .............................9
           1.5.2. Assured Forwarding (AF) .............................9
           1.5.3. Expedited Forwarding (EF) ..........................10
           1.5.4. Class Selector (CS) ................................10
           1.5.5. Admission Control ..................................11
   2. Service Differentiation ........................................11
      2.1. Service Classes ...........................................12
      2.2. Categorization of User Service Classes ....................13
      2.3. Service Class Characteristics .............................16
      2.4. Deployment Scenarios ......................................21
           2.4.1. Example 1 ..........................................21
           2.4.2. Example 2 ..........................................23
           2.4.3. Example 3 ..........................................25
   3. Network Control Traffic ........................................27
      3.1. Current Practice in the Internet ..........................27
      3.2. Network Control Service Class .............................27
      3.3. OAM Service Class .........................................29
   4. User Traffic ...................................................30
      4.1. Telephony Service Class ...................................31
      4.2. Signaling Service Class ...................................33
      4.3. Multimedia Conferencing Service Class .....................35
      4.4. Real-Time Interactive Service Class .......................37
      4.5. Multimedia Streaming Service Class ........................39
      4.6. Broadcast Video Service Class .............................41
      4.7. Low-Latency Data Service Class ............................43
      4.8. High-Throughput Data Service Class ........................45
      4.9. Standard Service Class ....................................47
      4.10. Low-Priority Data ........................................48
   5. Additional Information on Service Class Usage ..................49
      5.1. Mapping for Signaling .....................................49
      5.2. Mapping for NTP ...........................................50
      5.3. VPN Service Mapping .......................................50
   6. Security Considerations ........................................51

Babiarz, et al.              Informational                      [Page 2]
RFC 4594        Guidelines for DiffServ Service Classes      August 2006

   7. Acknowledgements ...............................................52