Orolia Spectracom VelaSync 1232, User Manual

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2.10.7 NTP Reference Configuration
VelaSync's NTP Service needs to be setup such that it utilizes the time source ("input ref-
erence") you want it to use. There are two options for an NTP Server to derive its time
from:
a.
The NTP Service uses VelaSync's System Time System Time is the time derived
from the internal Timing System. The Timing System is the time server's central
time processing engine. It consumes and processes time and 1PPS obtained from an
external input reference e.g., typically GNSS., i.e. typically the GNSS reference (or
IRIG, ASCII data input, etc.), and distributes that time over the NTP network. This is
called
Stratum 1 Operation , because VelaSync will be the Stratum 1 (or primary)
server. This is the most common configuration.
2.10.8 NTP Servers and Peers
VelaSync can be configured to receive time from one or more available NTP Servers
(VelaSyncs or different models). This allows for NTP Servers on a timing network to be con-
figured as potential (fallback) input time references for VelaSync System Time syn-
chronization. In the event that a current reference becomes unavailable, VelaSync can
fallback to the other NTP Servers available on the network.
A group of NTP servers at the same Stratum level (Stratum 1 time servers, for example)
are considered as
NTP Peers to each other.
NTP Servers at the same Stratum level
If VelaSync is configured to obtain time from other NTP Servers at the same Stratum level
(i.e., NTP Peers) but is currently using a different input reference as its selected reference,
VelaSync will report to the network (via the NTP time stamps) that it is a
Stratum 1 time
server. Should, however, all input references except the other NTP server(s) become
unavailable, VelaSync will then drop to a
Stratum 2 time server (with System Time being
derived from the NTP time packets being received from the other NTP Peers.
Holdover
If VelaSync is synchronized to another NTP Server or reference, and that server or ref-
erence subsequently loses sync or becomes unavailable (with no other higher priority input
references being present and valid), VelaSync will then go into the
Holdover mode. It will
remain in Holdover mode until any enabled and valid input reference becomes available
again, or until the Holdover period expires, whichever occurs first.
During Holdover mode, NTP will remain at the same Stratum level it was before entering
the Holdover mode and can continue to be the reference to the network. However, if no
input reference becomes available before the Holdover period expires, Time Sync will be
lost and shortly thereafter, NTP will report to the network that it is now at Stratum 15. A
status of Stratum 15 will cause the network to ignore VelaSync as an NTP time reference.
2.10 Configure NTP
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