Subject: [Ntp] [Technical Errata Reported] RFC5905 (5600)

From: RFC Errata System <[email-masked]>
Date: Mon, 14 Jan 2019 17:43:10 -0800 (PST)

The following errata report has been submitted for RFC5905,
"Network Time Protocol Version 4: Protocol and Algorithms Specification".

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You may review the report below and at:
http://www.rfc-editor.org/errata/eid5600

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Type: Technical
Reported by: Takashi Nakamoto <[email-masked]>

Section: 10.

Original Text
-------------
   Let the first stage offset in the sorted list be theta_0; then, for
   the other stages in any order, the jitter is the RMS average

                          +-----                 -----+^1/2
                          |  n-1                      |
                          |  ---                      |
                  1       |  \                     2  |
      psi   =  -------- * |  /    (theta_0-theta_j)   |
                (n-1)     |  ---                      |
                          |  j=1                      |
                          +-----                 -----+

Corrected Text
--------------
   Let the first stage offset in the sorted list be theta_0; then, for
   the other stages in any order, the jitter is the RMS average

               +-----                             -----+^1/2
               |              n-1                      |
               |              ---                      |
               |    1         \                     2  |
      psi   =  | -------- *   /    (theta_0-theta_j)   |
               |  (n-1)       ---                      |
               |              j=1                      |
               +-----                             -----+

Notes
-----
The formula to calculate jitter "psi" in section "10.  Clock Filter Algorithm" is incorrect, and also inconsistent with the formulate to calculate "psi_s" in section "11.2.2.  Cluster Algorithm".

"psi" is defined as RMS average, so the term 1/(n-1) should be within [ ]^1/2 block.

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-------------
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RFC5905 (draft-ietf-ntp-ntpv4-proto-13)
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Title               : Network Time Protocol Version 4: Protocol and Algorithms Specification
Publication Date    : June 2010
Author(s)           : D. Mills, J. Martin, Ed., J. Burbank, W. Kasch
Category            : PROPOSED STANDARD
Source              : Network Time Protocol
Area                : Internet
Stream              : IETF
Verifying Party     : IESG