9 LTOS7 Management and Monitoring
9.1.4.5 SHS Configuration
SHS is the abbreviation for Secure Hybrid System and is available on LANTIME systems with two reference
clocks. When the SHS mode is enabled only the currently active clock is used for passing the timing signal on
to the NTP service, the other clock is indicated as “no select” and used only for measuring and comparing a
time difference between both receivers.
In this respect SHS is different from a redundant mode. In redundant mode a switching unit switches be-
tween one or the other clock, depending on its availability and sync status and the active clock passes the
timing signal on the NTP service.
SHS mode takes care for a secure operation and it steps into action when a time difference between both
receivers exceeds a configurable time limit.
When this happens the alarms will be trigged and send out via configured notification channels (e.g SNMP trap,
email, syslog message). Besides, the NTP should be stopped in this case too to support the secure operation
of the timing service, therefore you have to select “Stop NTP Service on Time Limit Error” at this step.
On the other hand, in IMS Systems with two reference clocks the timing signal coming from the clocks is
continuously measured with a RSC card (Redundant Switch Control unit) and compared against each other.
The measurements are forwarded to the SHS mode if this is enabled. Similar as in LANTIME systems with
SHS, the alarms can be triggered when a difference of the two signals exceeds the configured time limit settings
and the NTP service should be configured to stop.
SHS-Mode
The SHS mode can be selectively enabled or disabled via this selection box. If the SHS mode is disabled, no
time comparison takes place and the times of both receivers are transferred directly to the NTP service. The
NTP service then decides autonomously which time is used for synchronization (redundant mode).
Time Limit Warning Level
If the calculated time difference between the two reference clocks exceeds the configured value, the LANTIME
generates a "SHS Time Limit Warning" alarm. This alarm can be sent via e-mail or SNMP Trap, if it is config-
ured correspondingly in the Notification settings.
(see also configuration chapter "Web GUI
→
Notification
→
In LANTIME IMS systems with a built-in RSC, the parameter is configured in nanoseconds. For systems
without an RSC in milliseconds.
Time Limit Error Level (ms)
If the calculated time difference between the two reference clocks exceeds the configured value, the LANTIME
generates a "SHS Time Limit Warning" alarm. This alarm can be sent via e-mail or SNMP Trap, if it is config-
ured correspondingly in the Notification settings.
In LANTIME IMS systems with a built-in RSC, the parameter is configured in nanoseconds. For systems
without an RSC in milliseconds.
LANTIME CPU Expansion Shelf
Date: 2nd July 2020
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