PIE (Proportional Integral Controller Enhanced)

A group of authors from Cisco Systems proposed PIE as a Active Queue Management controller alternative to CoDel. The authors claim that CoDel cannot practically be implemented in hardware because (1) it requires packets to be timestamped when enqueued, and (2) the drop decision happens on dequeue, so all packets have to be queued. PIE performs the drop decision on enqueue, like RED and most other AQM mechanisms. PIE was presented at IETF 85 in December 2012 (slides). Evaluation results based on simulations were presented at IETF 86 in March 2013 (slides). RFCs 8033 (Experimental) and 8034 (Informational) were issued in February 2017.

A PIE implementation for Linux was integrated into the Git kernel in January 2014.

PIE has been recommended as an AQM mechanism in a recent draft of the DOCSIS 3.0 specification.


  • RFC 8033, Proportional Integral Controller Enhanced (PIE): A Lightweight Control Scheme to Address the Bufferbloat Problem, R. Pan, P. Natarajan, F. Baker, G. White, February 2017
  • RFC 8034, Active Queue Management (AQM) Based on Proportional Integral Controller Enhanced PIE) for Data-Over-Cable Service Interface Specifications (DOCSIS) Cable Modems, G. White, R. Pan, February 2017
  • G. White, Active Queue Management Algorithms For DOCSIS 3.0, April 2013

-- Simon Leinen - 2013-06-14 - 2017-03-01

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Topic revision: r19 - 2017-03-01 - SimonLeinen
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