With the design of master clock at the core of the network having GNSS/GPS reference, all the nodes placed at Edge/Access have to follow the master running at Core.  The moment GNSS/GPS reference fails at the master at the core, then the slave clocks running at the edge/access no longer get the accurate time stamps from the master. Also the slave clocks don't have the idea of the asymmetry introduced by all means from their master.

With the use of A-PTS, The nodes at the edge/access can have GNSS/GPS as primary clock source and PTP as secondary. When the GNSS/GPS reference lost by any means at the Slave clock, then slave will fall back to the backup PTP session running  between its Master at Core and to it. Also the slave apply the asymmetry correction seen at the servo.

This paper, we will brief on the test strategies involved to get comply to the A-PTS performance standard for G.8275.2 profile. With the increased amount of time sensitive applications, it is very much need to qualify the A-PTS clock for the better performance.