6. Policing and Shaping

  1. Miguel Barreiros1 and
  2. Peter Lundqvist2

Published Online: 20 DEC 2010

DOI: 10.1002/9780470976814.ch6

QOS-Enabled Networks: Tools and Foundations

QOS-Enabled Networks: Tools and Foundations

How to Cite

Barreiros, M. and Lundqvist, P. (2011) Policing and Shaping, in QOS-Enabled Networks: Tools and Foundations, John Wiley & Sons, Ltd, Chichester, UK. doi: 10.1002/9780470976814.ch6

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



  • policing and shaping - policer and shaper tools as black boxes, mechanics of tools;
  • black box, policer operation, straightforward - at ingress, traffic flow with certain bandwidth value;
  • policer, limiting input traffic - to a certain bandwidth limit;
  • policer, implemented using a token bucket algorithm - and two key parameters;
  • A token bucket, using concept of credits - credit consumption of transmitting a packet, function of its size;
  • full operation of token bucket - depleted of credits, actively refilled with credits;
  • token bucket, and its workings - two values configured in a policer, bandwidth limit and burst size limit;
  • absorbing traffic bursts - traffic burst, as abrupt variation in traffic pattern;
  • capability of policer for burst absorption - connected to credits in token bucket;
  • shapers and leaky buckets, a shaper implemented - using a leaky bucket concept, called delay buffer


This chapter contains sections titled:

  • Token Buckets

  • Traffic Bursts

  • Dual-Rate Token Buckets

  • Shapers and Leaky Buckets

  • Excess Traffic and Oversubscription

  • Comparing and Applying Policer and Shaper Tools

  • Conclusion

  • Reference