[Ntp] [Errata Verified] RFC5905 (5601)
RFC Errata System <rfc-editor@rfc-editor.org> Mon, 26 September 2022 00:11 UTC
Return-Path: <wwwrun@rfcpa.amsl.com>
X-Original-To: ntp@ietfa.amsl.com
Delivered-To: ntp@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id A8B29C14F744; Sun, 25 Sep 2022 17:11:50 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -3.959
X-Spam-Level:
X-Spam-Status: No, score=-3.959 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.249, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_ZEN_BLOCKED_OPENDNS=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01, URIBL_DBL_BLOCKED_OPENDNS=0.001, URIBL_ZEN_BLOCKED_OPENDNS=0.001] autolearn=unavailable autolearn_force=no
Received: from mail.ietf.org ([50.223.129.194]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id YJ2ZkVTkyhmP; Sun, 25 Sep 2022 17:11:45 -0700 (PDT)
Received: from rfcpa.amsl.com (rfc-editor.org [50.223.129.200]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 69BB7C1522B7; Sun, 25 Sep 2022 17:11:45 -0700 (PDT)
Received: by rfcpa.amsl.com (Postfix, from userid 499) id 3166D4C956; Sun, 25 Sep 2022 17:11:45 -0700 (PDT)
To: takashi.nakamoto@nao.ac.jp, mills@udel.edu, jrmii@isc.org, jack.burbank@jhuapl.edu, william.kasch@jhuapl.edu
From: RFC Errata System <rfc-editor@rfc-editor.org>
Cc: ek.ietf@gmail.com, iesg@ietf.org, ntp@ietf.org, iana@iana.org, rfc-editor@rfc-editor.org
Content-Type: text/plain; charset="UTF-8"
Message-Id: <20220926001145.3166D4C956@rfcpa.amsl.com>
Date: Sun, 25 Sep 2022 17:11:45 -0700
Archived-At: <https://mailarchive.ietf.org/arch/msg/ntp/amjHY7Nz6g8rZ1otMB26wPmoezs>
Subject: [Ntp] [Errata Verified] RFC5905 (5601)
X-BeenThere: ntp@ietf.org
X-Mailman-Version: 2.1.39
Precedence: list
List-Id: Network Time Protocol <ntp.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/ntp>, <mailto:ntp-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/ntp/>
List-Post: <mailto:ntp@ietf.org>
List-Help: <mailto:ntp-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/ntp>, <mailto:ntp-request@ietf.org?subject=subscribe>
X-List-Received-Date: Mon, 26 Sep 2022 00:11:50 -0000
The following errata report has been verified for RFC5905, "Network Time Protocol Version 4: Protocol and Algorithms Specification". -------------------------------------- You may review the report below and at: https://www.rfc-editor.org/errata/eid5601 -------------------------------------- Status: Verified Type: Technical Reported by: Takashi Nakamoto <takashi.nakamoto@nao.ac.jp> Date Reported: 2019-01-15 Verified by: Erik Kline (IESG) Section: 11.2.3. Original Text ------------- | s.rootdisp <-- p.epsilon_r + p.epsilon + | | p.psi + PHI * (s.t - p.t) | | + |THETA| | | s.refid <-- p.refid | | s.reftime <-- p.reftime | | s.t <-- p.t | +-------------------------------------------+ Figure 25: System Variables Update There is an important detail not shown. The dispersion increment (p.epsilon + p.psi + PHI * (s.t - p.t) + |THETA|) is bounded from below by MINDISP. Corrected Text -------------- | s.rootdisp <-- p.epsilon_r + p.epsilon + | | p.psi + PHI * (t_s - p.t) | | + |THETA| | | s.refid <-- p.refid | | s.reftime <-- p.reftime | | s.t <-- p.t | +-------------------------------------------+ Figure 25: System Variables Update where t_s is the time when the system variables are updated. There is an important detail not shown. The dispersion increment (p.epsilon + p.psi + PHI * (t_s - p.t) + |THETA|) is bounded from below by MINDISP. Notes ----- In the same section, it is said that "By rule, an update is discarded if its time of arrival p.t is not strictly later than the last update used s.t." This means that p.t > s.t when the system variable is updated. Hence, (s.t - p.t) is negative. It may lead to a negative dispersion, but, by definition, the dispersion cannot be negative. So, the original formula should be wrong. Because the dispersion is defined as the value that grows at constant rate PHI, s.rootdisp should be s.rootdisp <-- p.epsilon_r + p.epsilon + p.psi + PHI * (t_s - p.t) + |THETA| where t_s is the time when the system variables are updated. The symbol t_s is arbitrary because it is not defined in other places. --- [verifier notes] >From https://mailarchive.ietf.org/arch/msg/ntp/CHcBo-my1WdRg5PbhSU8aFlIS_k/ : """ ... the reported section with is indeed erroneous, and s.t should be replaced with c.t, defined in section 9.1/12. The attached note seems inaccurate in the statement that a new name (t_s) is needed, since c.t covers the required concept... """ -------------------------------------- RFC5905 (draft-ietf-ntp-ntpv4-proto-13) -------------------------------------- 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 Protocols Area : Internet Stream : IETF Verifying Party : IESG
- [Ntp] [Errata Verified] RFC5905 (5601) RFC Errata System