To set up PTP synchronization, the first thing is to identify the clocks via special types of multicast that efficiently get distributed accross the network environment. Once the master clock is identified, the intervening clock such as a boundary clocks will be a slave to the grand master and in turn the intervening clock a master to the ones with which it will interoperate. In the case of transparent clock operations, the intermediate clock can be removed and then each edge slave clock can communicate directly with the grand master clock.

The slave clock takes the 4 timestamps (discussed in the previous video) and computes its offset which is the inherent jitter or delay. The time stamp function is located at the MII (Media Independent Interface). The time stamps between the different physical interfaces of the device are maintained by including this offset. There is a limitation of 16 hops from the grand master clock otherwise the time stamp will start decaying. In this situation, it is suggested to break up the network into different time domains.


Narrated by iS5 Communications' Field Application Engineer Dominic Iadonisi.

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