The Leap Second is Coming - Are You Ready?

At the end of this month a leap second will be inserted. Time to check once more if your systems are ready for it.

For detailed information about the leap second please refer to our news articles of August 5th, 2016 and July 22nd, 2016 and of course our general leap second information page.

We would like to inform you how you can find out if your Meinberg products and NTP clients correctly received the leap second announcement and therefore are prepared to handle it correctly on December 31st.

GPS sends the leap second announcement since several months already, other time signals like DCF77 (PZF) start to send the announcement only one hour before it actually happens.

LANTIME and SyncFire Products

All Meinberg products running LTOS6 can be checked as follows. Please note that it is sufficient if you verify the correct leap second information on your Meinberg product with one of the listed methods.

• The 'Last Messages' log on the main page of the web user interface contains a "Leap Second Announced" entry, in newer versions (6.20) this entry also contains the date of the leap second event. If the system is running since a long time, this log entry might have been rotated out of the file and therefore is not visible anymore.
• Version 6.18 and later: Open the 'Notification' page of the web UI and the "'Notification Events' section. In the line 'LEAP SECOND ANNOUNCED' you can see if and for how long this status is active. If the announcement has been received/detected correctly, you should see a text 'since ...' in the 'Trigger' column together with an information how long ago this announcement has been received. If the 'Trigger' column is empty, the announcement has not been detected correctly.
• On the 'System' page of the web UI in the secion called 'System Information' you can use the function 'show receiver information' to display detailed information about the current state of your reference clock (i.e. the builtin GPS receiver). In the files shown, you can look for a 'Leapseconds' or 'Leap Seconds' line and it should contain the date Dec 31, 2016 as well as the values 17 and 18.
• On the command line interface (CLI) you can also read the receiver information by using the corresponding CLI command:
  

  less /gps_info
  

  If this file is not found, other files might be available (this depends on your specific LANTIME model and firmware version):
  

  /ref_info
  /xmr_info
  /gln_info
  /pzf_info
  /mrs_info
  

In case of any uncertainties or questions you can at any time contact your Meinberg technical support for further assistance.

NTP Leap Second Announcement

On Meinberg LTOS6 systems

On LANTIME systems with radio signal receivers like GPS or PZF the NTP service will be informed about the upcoming leap second automatically, although with some time signals like DCF77/PZF this happens only one hour before the actual event takes place. This might be too short to allow the information to be passed on to all connected clients and intermediate servers, therefore it makes sense to provide this information as early as possible to the NTP daemon. Doing this requires to install (or update) a leap second file. This file is also required if the time reference of the NTP service does not provide any leap second announcement or simply does not support it at all. This is true for (for example) PPS signals or most IRIG time codes.

In order to find out whether the NTP daemon on your LTOS6 device correctly detected the leap second announcement, you can check the ntpd sysvars (this works with 4.2.6 and newer). On LANTIME systems, these are available on the "Statistics" page of the Web UI under the "NTP Debug" section. You should see this value:

leapsec=201701010000

This confirms that the leap second file has been correctly read by the NTP service on your LTOS6 device.

On other systems using NTP

The currently valid leap second file of the IERS can be downloaded from here: https://hpiers.obspm.fr/iers/bul/bulc/ntp/leap-seconds.list and then, with the reference implementation of NTP (starting with version 4.2.6) it can be introduced to NTP by adding a line "leapfile /path/to/file" to the NTP configuration file.

If this configuration statement is already included, NTP versions starting with 4.2.8 do not even need to be restarted as they automatically detect a changed file (this is checked at least once every 24 hours). So, for these newer versions it is enough to replace the old leap second file with the new one and wait for one day to see if NTP recognized it. If the configuration statement had to be added and if a version before 4.2.8 is in use, the NTP daemon (ntpd) needs to be restarted to read in the updated leap second information.

You can use the ntpq command to check if a running ntpd has correctly read the leap second file:

ntpq -c 'rv 0 leapsec'

This will read out the leapsec variable.

For the upcoming leap second at the end of December 2016 you should see a value

leapsec=201701010000

in the response to this command.

Meinberg Leap Second Updates

If one of your devices does not correctly indicate a leap second announcement for December 31, 2016 you should install the leap second update for your specific firmware version. For V6 we recently improved the update so that it will now correctly identify whether a restart of NTP, a restart of the LANTIME daemon or a system reboot is required in order to apply the updated leap second information. In addition to that we improved the messages before, during and after the update execution.

You can find the download links to all leap second updates in our Meinberg Leap Second Information news article of August 5th, 2016.