Based on your previous focus on dual-sensor PTP synchronization scenarios, BMCA (Best Master Clock Algorithm) is the core mechanism for automatically electing master and slave clocks in the PTP protocol. Its working logic in a dual-sensor scenario is as follows:
Initial State Interaction: After both sensors start up, they periodically broadcast Announce messages to the entire network. These messages carry their own priority, clock precision, clock type, and other core attributes.
Round-by-Round Attribute Comparison: After receiving each other's Announce messages, the two sensors compare attributes according to fixed rules: first, they compare the priority1 value (the smaller the value, the higher the priority); then they compare the clock precision and priority2 value; finally, they compare the device MAC addresses to select the better clock.
Automatic Role Assignment: The sensor with the better attributes automatically becomes the master clock, and the other automatically switches to slave clock. The slave clock will then continuously follow the master clock to complete time synchronization.
Dynamic Maintenance and Updates: If the network is interrupted and then restored, or if the clock attribute of a sensor changes, BMCA will re-execute the comparison process, automatically updating the master-slave roles to ensure the entire network is always synchronized based on the optimal clock.
In dual-sensor scenarios, manually setting a differentiated priority1 value allows BMCA to stably output a fixed master-slave role, avoiding frequent switching conflicts caused by automatic election.
