EndRun Meridian II, User Manual

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M e r i d i a n I I U s e r M a n u a l 96
C H A P T E R N I N E
97 M e r i d i a n I I U s e r M a n u a l
P T P / I E E E - 1 5 8 8
250us Clock is synchronized or in holdover, PTP clock < 250 microseconds
1ms Clock is synchronized or in holdover, PTP clock < 1 millisecond
2.5ms Clock is synchronized or in holdover, PTP clock < 2.5 milliseconds
10ms Clock is synchronized or in holdover, PTP clock < 10 milliseconds
Unknown Clock is unsynchronized, TFOM = 9
The PTP Leap 59 second indicator is either TRUE or FALSE. The Leap 59 is TRUE if the PTP Tim-
escale is PTP and the last minute of the current UTC day contains 59 seconds, otherwise it is FALSE.
The PTP Leap 61 second indicator is either TRUE or FALSE. The Leap 61 is TRUE if the PTP Tim-
escale is PTP and the last minute of the current UTC day contains 61 seconds, otherwise it is FALSE.
The PTP Time Traceable indicator is either TRUE or FALSE. The Time Traceable is TRUE if the
Time Scale is PTP and the Clock Class is Synchronized or Holdover, otherwise it is FALSE.
The PTP Frequency Traceable indicator is either TRUE or FALSE. The Frequency Traceable is
TRUE if the Time Traceable is TRUE, otherwise it is FALSE.
The PTP Transmission Mode is either Multicast or Hybrid. Multicast Mode is the default and is de-
fined in the IEEE-1588 standard. All packets sent from the Grandmaster are Multicast. Hybrid Mode
uses Multicast and Unicast. In this mode, delay response messages are sent Unicast in response to
the slave delay request. NOTE: Unicast messages are only sent when the Delay Mechanism is con-
figured to E2E.
About the PTP Second
and UTC Time
The PTP Time Mode selections are PTP and UTC. The IEEE-1588 standard defines the PTP epoch
beginning at 0 hours on 1 January 1970. The time measured since this epoch is designated in the
standard as PTP seconds. The PTP second is monotonic so does not include leap seconds.
Unlike PTP, the UTC second is not monotonic, that is, from time-to-time there will be leap second
insertions. The last second of a leap insertion day is 23:59:60 making the day one second longer than
a normal day ending at 23:59:59.
PTP Second
When the PTP Time Mode is set to PTP, the slave clocks must utilize the current leap second and leap
second pending flags (leap_59 or leap_61) to convert the PTP second to UTC.
UTC Time
When the PTP Time Mode is set to UTC, then there will be a one second jump in time when a leap
second insertion occurs. If the PTP slave does not account for this, it will also jump. Avoid this by
using PTP Time Mode.