Time Sources are the fundamental dependency of the Timebeat application and what we can do with those sources may be a little different to what you are used to.
This is because Timebeat can not only be configured to use the traditional BMCA (Best Master Clock Algotrithm) steering method but also our highly recommended MSSA (Multi-Source Synchronisation Algorithm) method.
To understand what model suits your environment best, get in touch with one of our team here at TImebeat and they can discuss everything you need to know. Or alternatively, you might be interested in checking out our Squared guide for the best sync solution.
There are several reasons for using BMCA or MSSA, typically either model will work to the same effect but utilising Timebeats capabilities to operate as a Grandmaster or a Boundary clock allows for greater resiliency in your sync configuration and network.
In principle we always recommend having more than one source of UTC for each device, you can configure two separate instances of PTP sources using BMCA or MSSA without using multiple PTP domains, or similarly you can configure each source to have a different domain. If you are using multiple domains however and the Squared configuration please check out the guide as domains hold a specific purpose in Squared beyond just additional sources.
In short 2 sources configured same domain BMCA will be used.
2 sources configured with different domains MSSA will be used.
Having multiple sources that are monitored and reported allows you to have a level of validation or traceability to your clock sync solution. This can be important for maintaining SLA's or compliance with various regulations.
When using MSSA Timebeat will utilise the median time source, this ensures your sync doesn't jump around but holds a consistent route forward making for steady and stable sync.
What this means in practice is that if you have 3 time sources it will synchronise to the source that is in the middle, an example:
Time source 1 is reading +4 microseconds,
Source 2 is reading -1 microseconds, and,
Source 3 is reading +2 microsecond
Timebeat would synchronise with source 3.
This may appear to be counterproductive as source 2 comes across as the most accurate to UTC reading -1 microseconds however it is our view that this is the source that disagrees the most against all other sources, therefore, making it a "bad" source.
This system protects integrity, stability and accuracy to UTC. Also, serves to have triple redundancy.
Timebeat is flexible and can obtain UTC from a multitude of inputs which are: PTP, NTP, PPS and NMEA. If there is a source of UTC not present that you require let us know and we will see if we can make that happen for you.
For all Clock config information check out our guide as there are many options you can use to obtain UTC: timebeat.yml - UTC Source configuration explained