Proportional Integral Controller Enhanced (PIE): A Lightweight Control Scheme to Address the Bufferbloat Problem
RFC 8033

• Status
• IESG evaluation record
• IESG writeups
• Email expansions
• History

• Versions
• 00
• 01
• 02
• 03
• 04
• 05
• 06
• 07
• 08
• 09
• 10

Internet Engineering Task Force (IETF)                            R. Pan
Request for Comments: 8033                                  P. Natarajan
Category: Experimental                                     Cisco Systems
ISSN: 2070-1721                                                 F. Baker
                                                            Unaffiliated
                                                                G. White
                                                               CableLabs
                                                           February 2017

            Proportional Integral Controller Enhanced (PIE):
    A Lightweight Control Scheme to Address the Bufferbloat Problem

Abstract

   Bufferbloat is a phenomenon in which excess buffers in the network
   cause high latency and latency variation.  As more and more
   interactive applications (e.g., voice over IP, real-time video
   streaming, and financial transactions) run in the Internet, high
   latency and latency variation degrade application performance.  There
   is a pressing need to design intelligent queue management schemes
   that can control latency and latency variation, and hence provide
   desirable quality of service to users.

   This document presents a lightweight active queue management design
   called "PIE" (Proportional Integral controller Enhanced) that can
   effectively control the average queuing latency to a target value.
   Simulation results, theoretical analysis, and Linux testbed results
   have shown that PIE can ensure low latency and achieve high link
   utilization under various congestion situations.  The design does not
   require per-packet timestamps, so it incurs very little overhead and
   is simple enough to implement in both hardware and software.

Pan, et al.                   Experimental                      [Page 1]
RFC 8033                           PIE                     February 2017

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for examination, experimental implementation, and
   evaluation.

   This document defines an Experimental Protocol for the Internet
   community.  This document is a product of the Internet Engineering
   Task Force (IETF).  It represents the consensus of the IETF
   community.  It has received public review and has been approved for
   publication by the Internet Engineering Steering Group (IESG).  Not
   all documents approved by the IESG are a candidate for any level of
   Internet Standard; see Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc8033.

Copyright Notice

   Copyright (c) 2017 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
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Pan, et al.                   Experimental                      [Page 2]
RFC 8033                           PIE                     February 2017

Table of Contents

   1. Introduction ....................................................3
   2. Terminology .....................................................5
   3. Design Goals ....................................................5
   4. The Basic PIE Scheme ............................................6
      4.1. Random Dropping ............................................7
      4.2. Drop Probability Calculation ...............................7
      4.3. Latency Calculation ........................................9
      4.4. Burst Tolerance ...........................................10
   5. Optional Design Elements of PIE ................................11
      5.1. ECN Support ...............................................11
      5.2. Dequeue Rate Estimation ...................................11
      5.3. Setting PIE Active and Inactive ...........................13
      5.4. Derandomization ...........................................14
      5.5. Cap Drop Adjustment .......................................15
   6. Implementation Cost ............................................15
   7. Scope of Experimentation .......................................17
   8. Incremental Deployment .........................................17
   9. Security Considerations ........................................18
   10. References ....................................................18