For complete redundancy, Timebeat Enterprise offers the ability to configure secondary time sources.
Primary Sources are what you are used to actively synchronise your device. These would be your main sources of UTC. Secondary sources can be configured exactly the same as the primary sources in the configuration file under the heading Secondary sources.
The top graph shows 3 unique sources of UTC configured as Primary sources. The bottom graph is showing a Secondary source of UTC which is not being actively synchronised but is monitored in real-time.
Secondary sources can use PTP, NTP, PPS or NMEA input just like primary sources and will also track/log offsets against your clocks. This means you can set alerts or monitor secondary sources which are not being used as actively as your primary sources.
This allows you to understand what they are up to any time of day with ease so that you can ensure that in a failover event your sources are still in sync and ready to use. This method also removes the ambiguity of BMCA which offers a similar failover solution but with BMCA and traditional PTP stacks you wouldn't have visibility on how the failover source is operating at. Although Timebeat can view and monitor BMCA failover devices this method of solution is not as optimised or as effective as having Primary and Secondary configuration.
Timebeat tracks and logs this data for one simple reason, even though it is not the aim for secondary sources to be active, when they do become active you need to be able to trust that they will be operational and provide accurate sync.
It is important to note that Secondary sources are not the same as sources configured to be monitor_only. monitor_only sources can be configured as Primary or Secondary but in all cases, they will never become an active source of UTC that Timebeat will synchronise against.
Secondary sources become active in synchronising your device when all primary sources are unavailable. In the event, a trigger event happens to enable the active state of a secondary source it would then be shown in the front end as a primary source. alerts can be set up for notification of when this happens, similarly once the primary sources are available again the secondary switches back and the primary source takes over.
For a more resilient model with dynamic self-healing synchronisation and source awareness (I.e. it knows what a good source is), check out the Squared guide.