[aqm] [Technical Errata Reported] RFC8033 (5095)

RFC Errata System <rfc-editor@rfc-editor.org> Thu, 24 August 2017 17:14 UTC

To: ropan@cisco.com, prenatar@cisco.com, fredbaker.ietf@gmail.com, g.white@cablelabs.com, spencerdawkins.ietf@gmail.com, ietf@kuehlewind.net, rs.ietf@gmx.at, wes@mti-systems.com
From: RFC Errata System <rfc-editor@rfc-editor.org>
Cc: liang_tian@affirmednetworks.com, aqm@ietf.org, rfc-editor@rfc-editor.org
Content-Type: text/plain; charset="UTF-8"
Message-Id: <20170824171351.45501B814EF@rfc-editor.org>
Date: Thu, 24 Aug 2017 10:13:51 -0700
Archived-At: <https://mailarchive.ietf.org/arch/msg/aqm/UmDWJltUEyqbE4O0Rh76KzyG0s8>
Subject: [aqm] [Technical Errata Reported] RFC8033 (5095)
Precedence: list

The following errata report has been submitted for RFC8033,
"Proportional Integral Controller Enhanced (PIE): A Lightweight Control Scheme to Address the Bufferbloat Problem".

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You may review the report below and at:
http://www.rfc-editor.org/errata/eid5095

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Type: Technical
Reported by: Liang Tian <liang_tian@affirmednetworks.com>

Section: 5.2

Original Text
-------------
      if PIE->in_measurement_ == TRUE:
         PIE->dq_count_ = PIE->dq_count_ + deque_pkt_size;
         if PIE->dq_count_ >= DQ_THRESHOLD then
            weight = DQ_THRESHOLD/2^16
            PIE->avg_dq_time_ = (now - PIE->measurement_start_) *
                                weight + PIE->avg_dq_time_ *
                                (1 - weight);
            PIE->dq_count_ = 0;
            PIE->measurement_start_ = now
         else
            PIE->in_measurement_ = FALSE;

Corrected Text
--------------
      if PIE->in_measurement_ == TRUE:
         PIE->dq_count_ = PIE->dq_count_ + deque_pkt_size;
         if PIE->dq_count_ >= DQ_THRESHOLD then
            weight = DQ_THRESHOLD/2^16
            PIE->avg_dq_time_ = (now - PIE->measurement_start_) *
                                weight + PIE->avg_dq_time_ *
                                (1 - weight);
            PIE->in_measurement_ = FALSE;

Notes
-----
There should not be an "else" because if PIE->dq_count_ >= DQ_THRESHOLD, this measurement is over: avg_dq_time is calculated and in_measurement is set to FALSE; otherwise dq_count has been increased before this "if" and now we wait for next packet. Resetting dq_count and measurement_start is not necessary because they will be set again when a new measurement begins.

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-------------
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RFC8033 (draft-ietf-aqm-pie-10)
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Title               : Proportional Integral Controller Enhanced (PIE): A Lightweight Control Scheme to Address the Bufferbloat Problem
Publication Date    : February 2017
Author(s)           : R. Pan, P. Natarajan, F. Baker, G. White
Category            : EXPERIMENTAL
Source              : Active Queue Management and Packet Scheduling
Area                : Transport
Stream              : IETF
Verifying Party     : IESG

[aqm] [Technical Errata Reported] RFC8033 (5095) RFC Errata System