Tru64 and NTP handling leap seconds (559 Views)
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Occasional Contributor
tyoung44
Posts: 9
Registered: ‎04-04-2012
Message 1 of 4 (559 Views)

Tru64 and NTP handling leap seconds

I am trying to locate information on how Tru64 and NTP handle the leap second issue.  If anyone has information or documentation I would greatly appreciate.

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boukari
Posts: 57
Registered: ‎02-25-2011
Message 2 of 4 (549 Views)

Re: Tru64 and NTP handling leap seconds

Hello,

try to see on /etC/services

NTP port is (123)

this link can helps you to define the issue:

http://www.eecis.udel.edu/~mills/ntp/html/debug.html

 

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black_cat
Posts: 16
Registered: ‎07-04-2011
Message 3 of 4 (539 Views)

Re: Tru64 and NTP handling leap seconds

Which version of Tru64 ?

 

Tru64 V5.1B support NTP Version 3.

 

Hence look at http://www.ietf.org/rfc/rfc1305.txt

and  at the manual pages.

 

# man -k ntp

 

Hopefully that's all you'll need.

 

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Matti_Kurkela
Posts: 6,271
Registered: ‎12-02-2001
Message 4 of 4 (537 Views)

Re: Tru64 and NTP handling leap seconds

For the leap second issue specifically, these parts of the NTP documentation would be relevant:

 

Leap Second Processing

http://www.eecis.udel.edu/~mills/ntp/html/leap.html

 

The NTP Timescale and Leap Seconds

http://www.eecis.udel.edu/~mills/leap.html

 

My knowledge from this topic is basically this:

 

Older versions of NTP (before ntpd 4.x) used to only care about UTC: they don't maintain any information on past leap seconds. When a NTP timesource knows a leap second is about to occur, it is supposed to set a "leap" flag in the NTP protocol. The flag should be set at the beginning of the day that will contain the leap second, and reset after the leap second has occurred.

 

The leap second flag can be checked using this command:

# ntpq -c "rv 0 leap"
status=06f4 leap_none, sync_ntp, 15 events, event_peer/strat_chg
leap=00

In this example, "leap=00" indicates no leap second is about to occur at the end of the current day.

 

At the time of the leap second, ntpd will manipulate the system clock in some architecture-specific way to take into account the existence of the leap second. Some operating systems can indicate this as UTC time value 23:59:60, others will just make the second 23:59:59 last twice as long as usual.

 

Newer versions of NTP (ntpd 4.x and newer) include a facility for reporting the TAI offset: leap-second-aware applications could use this to convert NTP timestamps to a leap-second-free TAI timescale. To enable this feature, the "autokey" security mechanism must be configured for use, since this feature is part of the "autokey" NTP protocol extension.

 

If you have a recent version of ntpd and it has the leapfile configured, this command can be used to verify the current TAI offset value and the time of the latest officially-decided leap second:

$ ntpq -c "rv 0 leapsec,tai"
tai=34, leapsec=201207010000

 This indicates ntpd knows the current TAI offset is 34 seconds, and the next leap second event will be 2012-06-30 23:59:60 UTC. (At the beginning of 1 July of this year (UTC), the TAI offset will be incremented to 35.)

 

The current leap second file can be downloaded from various standards laboratories, for example:

ftp://nist1-ny.ustiming.org/pub/leap-seconds.list

 

MK
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