Network Time Protocol Leap Smear REFID
draft-stenn-ntp-leap-smear-refid-01

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Last updated 2018-11-04
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Internet Engineering Task Force                                 H. Stenn
Internet-Draft                                   Network Time Foundation
Intended status: Standards Track                         October 4, 2018
Expires: April 7, 2019

                 Network Time Protocol Leap Smear REFID
                  draft-stenn-ntp-leap-smear-refid-01

Abstract

   Leap Seconds are part of UTC.  NTP timestamps are based on POSIX
   timestamps, which require each day to have exactly 86,400 seconds per
   day.  Some applications and environments choose to "smear" leap
   second corrections over a period that can last up to 24 hours' time,
   and implement NTP servers that offer smeared time to clients asking
   them for the time.

   Both NTP clients and operators have no current way to tell if an NTP
   server is offering leap-smeared time or not.  This is a problem.

   This proposal offers a mechanism by which clients (and operators) can
   trivially detect a server that is offering leap-smeared time.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on April 7, 2019.

Copyright Notice

   Copyright (c) 2018 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

Stenn                     Expires April 7, 2019                 [Page 1]
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   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Leap Smear REFID  . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   4
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   6.  Normative References  . . . . . . . . . . . . . . . . . . . .   5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   Leap Seconds are applied as needed to UTC in order to keep its time
   of day close to UT1's mean solar time.

   RFC 5905 [RFC5905] and earlier versions of NTP are the overwhelming
   method of distributing time on networks.  The timescale used by NTP
   is based on POSIX which, for better or worse, ignores any instances
   where there are not 86,400 seconds per day.

   Leap Seconds will continue to exist for the foreseeable future, and
   similarly, POSIX can be expected to ignore leap seconds for the
   foreseeable future.

   Different applications have different requirements for the stability
   of time during the application of a leap second.  Some applications
   are tolerant of a fast application of the correction, while other
   applications prefer to "smear" the leap second over a longer period,
   where the time reported by leap-second aware servers is gradually
   applied so there is no abrupt change to time during the processing of
   a leap second.

   While leap second processing can be expected to be properly handled
   by up-to-date software and by time servers, there are large numbers
   of out-of-date software installations and client systems that are
   just not able to properly handle a leap second correction.

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Internet-Draft   Network Time Protocol Leap Smear REFID     October 2018

   This proposal offers a way for a system to generate a REFID that
   indicates that the time being supplied in the NTP packet already
   contains an amount of leap smear correction, and what that amount is.

1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
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