Zenitel Marine Master Clock 70000, Technical User'S Manual

Page: 80 / 118

Document: DOK11086en01
Author: PM
Date: 2021-06-16
Page: 15 of 2
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WESTERSTRAND
Stratum when no external sync.
With this function it is defined which stratum level the NTP server shall adopt when it has been
synchronized but now is working standalone. Synchronized means that the master clock / time
central has received correct time, either from an external sync source, GPS or similar, or that the
time is set manually.
If the NTP server has never been synchronized it will have stratum value 16 and LI-bits of the NTP
message is set to 3 (clock unsynchronized).
Clogging prevention
The NTP server support access control with a call-gap function and can send kiss-o’-death
packets if needed. If this function is activated clients asking for time too often, interval less than 1
second, will be denied and a kiss-o’-death packet will be sent.
My ID / Key
The NTP Server authentication data. Use for MD5
authentication.
Client mode
FIRST. Always use the first server in the list if available. If not available, take next one.
This suits installations where it is more important to know exactly from where the clients get time
than to have the most accurate time. The other NTP servers in the list will then be more of backup
servers.
STRATUM. Use the NTP server with best stratum. The software sends a request to all servers in
the list and uses the time from the one with best stratum. If same stratum it will use the one that is
first in the server list. This suits installations where it is important that the time is coming from a time
server high up in the pyramid. MEDIAN. Send a request to all servers in the list and use the median
value (the NTP server that is in the middle). This will filter out all misleading time messages.
5 minute limit *
With this feature, the acceptance of incorrect time messages can be limited. The reason for this
limitation is to avoid "time jumps" in the event of functional disturbances. If the time message
coming from the NTP server differs more than 5 minutes compared to the clocks internal time,
this time message will be rejected.
The default setting is no limit.
Check box = Off; No restriction, accept all messages.
Check box = On; Only accept messages with a maximum time difference of 5 minutes.
* Please note that the Time Central has a general sync. limit feature that affects all modules. See
Special functions, section Sync. Limits. If this feature is activated it overrides the 5 minute limit
setting.
Only accept Stratum 1
This function makes it possible to synchronize to Stratum 1 time servers
only. Check box = Off ; synchronize to time server independent of
stratum level.
Check box = On ; synchronize only if time server is operating on Stratum 1 level.
WESTERSTRAND URFABRIK AB
P.O. Box 133 Tel. +46 506 48000 Internet: http://www.westerstrand.se
SE-545 23 TÖREBODA Fax. +46 506 48051 E-mail: info@westerstrand.se