Knowledge Base - FAQ

PTP Clock Terminology

Tuesday, December 31, 2019
Submitted by ryan.grace on October 23, 2021 - 5:33pm
Question: 
What are the various types of clock entities referred to in PTP?
Answer: 
There are 5 basic clock roles in PTP networks. - PRTC stands for Primary Reference Time Clock. This could be GNSS based or a direct connection to an international time keeping facility.  - T-GM stands for Telecom Grand Master. Within a collection of 1588 clocks one clock, the grandmaster clock, will serve as the primary source of time to which all others are ultimately synchronized.  - T-BC stands for Telecom Boundary Clock. A boundary clock is a clock with more than one PTP port. They are used to eliminate fluctuations produced by networks elements. The PTP port facing the Master source uses sync messages to updates its local clock. The other PTP port facing the downstream elements acts as a Master generating new SYNC messages to the downstream slaves. - T-TSC stands for  Telecom Slave Clocks or transparent clock. A transparent clock modifies PTP messages as they pass through it. Timestamps in the messages are corrected for time spent traversing the network to that point.  - Slave Clock. A slave clock is an end point for network syncrhonization (i.e. the end application) Though referred to by clock names, with the possible exception of the PRTC, these devices are network entities (switches, routers, etc..) and not merely clock devices. 

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