Leap Indicator - Microsemi SyncServer S200 User Manual

Glossary

Leap Indicator

The Leap Indicator (LI) is a two-bit binary number in the NTP packet header that provides
the following information:
Advance warning that a leap second adjustment will be made to the UTC timescale at the
n
end of the current day. Leap seconds are events mandated by the world time authority
(BIPM) in order to synchronize the UTC time scale with the earth's rotation.
Whether the NTP daemon is synchronized to a timing reference. The settings on the
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NTP - Prefs (on page 40) page affect LI behavior.
LI Value Meaning
00 0 No warning.
01 1 Leap second insertion: Last minute of the day has 61 seconds.
10 2 Leap second deletion: Last minute of the day has 59 seconds.
11 3 Alarm condition (Not synchronized)
When the SyncServer or NTP daemon is started or restarted, the leap indicator is set to "11",
the alarm condition. This alarm condition makes it possible for NTP clients to recognize that
an NTP server (the SyncServer) is present, but that it has yet to validate its time from its time
sources. Once the SyncServer finds a valid source of time and sets its clock, it sets the leap
indicator to an appropriate value. The
configured to generate an alarm and send notifications each time the leap indicator changes
state.
NTP Daemon
The Network Time Protocol (NTP) Daemon (a.k.a. "ntpd") listens for and responds to
requests from NTP clients. It also sends NTP requests to each of the NTP Associations and
qualifies each one. It synchronizes with the best NTP association and makes that time avail-
able to the
See the NTP - Config topics for more information.
Software Clock
The Software Clock time is initialized by the onboard real time clock (RTC) and con-
trolled/adjusted by the NTP daemon (ntpd) when it has a valid peer (e.g., Hardware Clock-
/SYMM_TE, factory default NTP association, user-configured peer, etc.).
The software clock time is represented on the display
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on the
NTP Leap Change Alarm
page can be
ADMIN - Alarms