Considerations for Assigning DiffServ Codepoints (DCSPs)
draft-custura-tsvwg-dscp-considerations-00

Document Type Active Internet-Draft (individual)
Authors Ana Custura  , Gorry Fairhurst  , Raffaello Secchi 
Last updated 2021-02-21
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TSVWG                                                         A. Custura
Internet-Draft                                              G. Fairhurst
Intended status: Informational                                 R. Secchi
Expires: August 25, 2021                          University of Aberdeen
                                                       February 21, 2021

        Considerations for Assigning DiffServ Codepoints (DCSPs)
               draft-custura-tsvwg-dscp-considerations-00

Abstract

   This document discusses the considerations for assigning new DiffServ
   Code Points (DCSPs).  It considers the common remarking behaviours
   that the Diffserv field might be subjected to along an Internet path.
   It also notes some implications of using a specific DSCP.

   This individual draft aims to seek comments and contributions from
   the TSVWG working group.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   3.  Current usage of DSCPs  . . . . . . . . . . . . . . . . . . .   3
     3.1.  IP-Layer Semantics  . . . . . . . . . . . . . . . . . . .   3
     3.2.  Network Control Traffic . . . . . . . . . . . . . . . . .   4
   4.  Remarking the DSCP  . . . . . . . . . . . . . . . . . . . . .   4
     4.1.  Bleaching the DSCP Field  . . . . . . . . . . . . . . . .   5
     4.2.  IP Type of Service manipulations  . . . . . . . . . . . .   5
       4.2.1.  Impact of ToS Precedence Bleaching  . . . . . . . . .   5
       4.2.2.  Impact of ToS Precedence Remarking  . . . . . . . . .   6
     4.3.  Remarking to a Particular DSCP  . . . . . . . . . . . . .   6
   5.  Interpretation of the IP DSCP at Lower Layers . . . . . . . .   7
     5.1.  Mapping Specified for IEEE 802.11 . . . . . . . . . . . .   7
     5.2.  Mappings Specified for MPLS . . . . . . . . . . . . . . .   8
     5.3.  Mapping Specified for Mobile Networks . . . . . . . . . .   9
     5.4.  Mappings Specified for Carrier Ethernet . . . . . . . . .   9
     5.5.  Remarking as a Side-effect of Another Policy  . . . . . .   9
   6.  Considerations for DSCP Selection . . . . . . . . . . . . . .  10
     6.1.  Effect of Bleaching . . . . . . . . . . . . . . . . . . .  10
     6.2.  Where the proposed DSCP > 0x07 (7)  . . . . . . . . . . .  10
     6.3.  Where the proposed DSCP < 0x07 (7)  . . . . . . . . . . .  10
   7.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  10
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  11
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  11
     10.2.  Informative References . . . . . . . . . . . . . . . . .  12
   Appendix A.  Revision Notes . . . . . . . . . . . . . . . . . . .  13
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  13

1.  Introduction

   The Differentiated Services (DiffServ) architecture has been deployed
   in many networks; it provides differentiated traffic forwarding based
   on the value of the Diffserv field [RFC2474] carried in the IP packet
   header.

   This document discusses considerations for assigning a new DiffServ
   Code Point (DCSP).  It considers some commonly observed DSCP
   remarking behaviours that might be expected to be experienced along
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