and VersaSync would be Stratum 2 (or higher). This operating mode can be
referred to as Stratum2 operation, secondary server operation, or NTP
Stratum Synchronization.
With a GNSS- capable time server it is possible to combine these two con-
figurations e.g., by assigning a higher reference priority to (a.), and a lower "fall-
back" priority to (b.). For more information on reference priority configuration,
see "Configuring Input Reference Priorities" on page173.
The NTP Stratum Model
The NTP Stratum model is a representation of the hierarchy of time servers in an
NTP network, where the Stratum level (0-15) indicates the device's distance to
the reference clock.
Stratum0 means a device is directly connected to e.g., a GPS antenna. Stratum0
devices cannot distribute time over a network directly, though, hence they must
be linked to a Stratum1 time server that will distribute time to Stratum2 servers
or clients, and so on. The higher the Stratum number, the more the timing accur-
acy and stability degrades.
The NTP protocol does not allow clients to accept time from a Stratum 15 device,
hence Stratum 15 is the lowest NTP Stratum.
A group of NTP servers at the same Stratum level (Stratum 2, for example) are
considered NTP Peers to each other. NTP Servers at a higher Stratum level, on
the other hand, are referred to as NTP Servers.
Note: Internet Time Servers should be configured as NTP Servers
and not as NTP Peers.
If VersaSync has no valid Timing System Reference, NTP Server or NTP Peers, the
NTP Stratum value is automatically downgraded to Stratum 15. This ensures that
its NTP clients will no longer use this VersaSync unit as a time reference.
Configuring "NTP Stratum 1" Operation
When the Timing System references of your VersaSync are normally available
(rather than being unavailable most of the time e.g., in areas with poor GNSS
reception), it is advisable to use the System Time as a reference to NTP, since this
provides NTP with the most accurate references. This mode is called Stratum 1
operation, since VersaSync operates as a Stratum1 NTP server.
To configure Stratum 1 operation for VersaSync:
1. Navigate to MANAGEMENT > NETWORK: NTP Setup:
2. Click the GEAR icon in the NTP Services panel.
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CHAPTER 2 • VersaSync User Manual Rev. 12
2.8 Configuring Network Settings
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