7. Queuing and Scheduling

  1. Miguel Barreiros1 and
  2. Peter Lundqvist2

Published Online: 20 DEC 2010

DOI: 10.1002/9780470976814.ch7

QOS-Enabled Networks: Tools and Foundations

QOS-Enabled Networks: Tools and Foundations

How to Cite

Barreiros, M. and Lundqvist, P. (2011) Queuing and Scheduling, in QOS-Enabled Networks: Tools and Foundations, John Wiley & Sons, Ltd, Chichester, UK. doi: 10.1002/9780470976814.ch7

Author Information

  1. 1

    Juniper Networks, Portugal

  2. 2

    Juniper Networks, Sweden

Publication History

  1. Published Online: 20 DEC 2010
  2. Published Print: 7 JAN 2011

ISBN Information

Print ISBN: 9780470686973

Online ISBN: 9780470976814



  • queuing and scheduling - tool, as the star of QOS realm;
  • commonly deployed mechanism, PB–DWRR - priority-based deficit weighted Round Robin;
  • queuing and scheduling, applied to interface - traffic split into multiple queues, scheduler deciding which type of treatment traffic each queue receives;
  • bandwidth parameter in queuing and scheduling - bandwidth parameter, referring to scheduling part of equation;
  • queuing and scheduling discipline - how resources are allocated;
  • leftover traffic, throttled or back-pressured into memory - partitioned across actual queues;
  • types of queuing disciplines - First in, first out (FIFO) queuing, Fair queuing (FQ), Priority queuing (PQ), Weighted fair queuing (WFQ) and Weighted round robin (WRR);
  • FIFO queuing - having certain limitations;
  • priority queuing (PQ) scheduling algorithm - simple method of supporting differentiated service classes;
  • Deficit Round Robin (DRR), or Deficit Weighted Round Robin (DWRR) - a modified weighted Round-Robin scheduling discipline, addressing limitations of WRR


This chapter contains sections titled:

  • Queuing and Scheduling Concepts

  • Packets and Cellification

  • Different Types of Queuing Disciplines

  • FIFO – First in, First out

  • Fair Queuing

  • Priority Queuing

  • Weighted Fair Queuing

  • Weighted Round Robin

  • Deficit Weighted Round Robin

  • Priority-Based Deficit Weighted Round Robin

  • Conclusions about the Best Queuing Discipline

  • Further Reading