Priority Switching Scheduler
draft-finzi-priority-switching-scheduler-04

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Internet Engineering Task Force                                    Baker
Internet-Draft
Intended status: Informational                                     Finzi
Expires: April 25, 2019                        TTTech Computertechnik AG
                                                                 Frances
                                                            ISAE-SUPAERO
                                                                    Kuhn
                                                                    CNES
                                                                  Lochin
                                                                Mifdaoui
                                                            ISAE-SUPAERO
                                                        October 22, 2018

                      Priority Switching Scheduler
              draft-finzi-priority-switching-scheduler-04

Abstract

   We detail the implementation of a network rate scheduler based on
   both a packet-based implementation of the generalized processor
   sharing (GPS) and a strict priority policies.  This credit based
   scheduler called Priority Switching Scheduler (PSS), inherits from
   the standard Strict Priority Scheduler (SP) but dynamically changes
   the priority of one or several queues.  Usual scheduling
   architectures often combine rate schedulers with SP to implement
   DiffServ service classes.  Furthermore, usual implementations of rate
   scheduler schemes (such as WRR, DRR, ...) do not allow to efficiently
   guarantee the capacity dedicated to both AF and DF DiffServ classes
   as they mostly provide soft bounds.  This means excessive margin is
   used to ensure the capacity requested and this impacts the number of
   additional users that could be accepted in the network.  PSS allows a
   more predictable output rate per traffic class and is a one fit all
   scheme allowing to enable both SP and rate scheduling policies within
   a single algorithm.

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Baker, et al.            Expires April 25, 2019                 [Page 1]
Internet-Draft        Priority Switching Scheduler          October 2018

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   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Context and Motivation  . . . . . . . . . . . . . . . . .   2
     1.2.  Definitions and Acronyms  . . . . . . . . . . . . . . . .   3
     1.3.  Priority Switching Scheduler in a nutshell  . . . . . . .   3
   2.  Priority Switching Scheduler  . . . . . . . . . . . . . . . .   5
     2.1.  Specification . . . . . . . . . . . . . . . . . . . . . .   5
     2.2.  Implementation with three traffic classes and one
           controlled queue  . . . . . . . . . . . . . . . . . . . .   9
     2.3.  Implementation with n controlled queues . . . . . . . . .  10
   3.  Usecase: benefit of using PSS in a Diffserv core network  . .  12
     3.1.  Motivation  . . . . . . . . . . . . . . . . . . . . . . .  12
     3.2.  New service offered . . . . . . . . . . . . . . . . . . .  14
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .  14
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  15
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  15
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .  15
     6.2.  Informative References  . . . . . . . . . . . . . . . . .  15
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  16

1.  Introduction

1.1.  Context and Motivation

   To enable DiffServ traffic classes and share the capacity offered by
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