[Pool] Leap second is coming

Jan Kasprzak kas at fi.muni.cz
Thu Apr 16 06:57:39 UTC 2015


thanks for the explanation. Few questions, though:

Martin Burnicki wrote:
: lst_hoe02 at 79365-rhs.de wrote:
: > Sorry for maybe asking the obvious but
: > 
: > - How to check if ntp is configured with a leap second file? Must it be
: > listed in ntp.conf or is there some default set?
: If you run "ntpq -c rv" and the output shows a "tai" value then ntpd has
: read a leap second file. For example:
: pc-martin:/etc # ntpq -c rv
: associd=0 status=0414 leap_none, sync_uhf_radio, 1 event, freq_mode,
: version="ntpd 4.2.8p2 at 1.3316-o Wed Apr  8 08:20:36 UTC 2015 (3)",
: processor="x86_64", system="Linux/3.16.7-7-desktop", leap=00, stratum=1,
: precision=-23, rootdelay=0.000, rootdisp=7937.673, refid=shm0,
: reftime=d8d9160e.2c2467ac  Wed, Apr 15 2015 18:53:34.172,
: clock=d8d91616.da49a196  Wed, Apr 15 2015 18:53:42.852, peer=55606, tc=4,
: mintc=3, offset=-0.053, frequency=0.000, sys_jitter=0.000000,
: clk_jitter=0.019, clk_wander=0.000, tai=35, leapsec=201507010000,
: expire=201512280000

	What is the best way to get the leap seconds file? The first
URL in Google search results is apparently redirecting to itself:


$ telnet www.ietf.org http
Trying 2400:cb00:2048:1::6814:55...
Connected to www.ietf.org.
Escape character is '^]'.
GET /timezones/data/leap-seconds.list HTTP/1.0
Host: www.ietf.org

HTTP/1.1 301 Moved Permanently
Date: Thu, 16 Apr 2015 06:43:23 GMT
Content-Type: text/html; charset=iso-8859-1
Connection: close
Set-Cookie: __cfduid=d748abdf575a81a453adb2bc21000c6c71429166589; expires=Fri, 15-Apr-16 06:43:09 GMT; path=/; domain=.ietf.org; HttpOnly
Location: http://www.ietf.org/timezones/data/leap-seconds.list
Server: cloudflare-nginx
CF-RAY: 1d7de9f5c27f08b1-FRA

<title>301 Moved Permanently</title>
<h1>Moved Permanently</h1>
<p>The document has moved <a href="http://www.ietf.org/timezones/data/leap-seconds.list">here</a>.</p>
Connection closed by foreign host.

: > - Without a leap second file ntp will simply decide based on the
: > majority of upstream ntp servers it it will pass the information or will
: > it pass the information from the "*" upstream?
: ntpd 4.2.6 and newer requires a majority of configured upstream servers
: to accept and send a leap second warning, *or* a refclock which can
: provide it, *or* a current leap second file which supersedes both other
: types of source.

	Apparently the majority of my upstream servers do not send
the leap second info - at least my "ntpq -c rv" does not show the "tai" value:

associd=0 status=061b leap_none, sync_ntp, 1 event, leap_event,
version="ntpd 4.2.8 at 1.3265-o Wed Dec 24 11:18:58 UTC 2014 (1)",
processor="x86_64", system="Linux/xxx-gentoo", leap=00, stratum=2,
precision=-23, rootdelay=4.481, rootdisp=32.150, refid=,
reftime=d8d9d764.d4be8e2e  Thu, Apr 16 2015  8:38:28.831,
clock=d8d9daa4.cc61c706  Thu, Apr 16 2015  8:52:20.798, peer=36704,
tc=10, mintc=3, offset=0.185567, frequency=17.438, sys_jitter=0.130071,
clk_jitter=0.164, clk_wander=0.013

	How can I tell which upstream servers announce the upcoming
leap second?

: If your server has a leap second file and inserts the leap second, but
: the upstream servers you have configured don't insert the leap second
: then your server will observe a 1 s offset after the leap second and,
: and will re-synchronize to the upstream server(s) a few minutes later,
: i.e. step the time to be wrong like the servers.

	So it is better to not have the leap seconds file configured,
when my upstream servers do not announce the tai offset?



| Jan "Yenya" Kasprzak   <kas at {fi.muni.cz - work | yenya.net - private}> |
| New GPG 4096R/A45477D5 -- see http://www.fi.muni.cz/~kas/pgp-rollover.txt |
| http://www.fi.muni.cz/~kas/     Journal: http://www.fi.muni.cz/~kas/blog/ |
           Smart data structures and dumb code works a lot better
           than the other way around.           --Eric S. Raymond

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