Multiple RAVENNA devices - PTP Priorities considerations.

According to IEEE1588-2008, the PTP Master can be elected via its priority value.

To access Merging devices PTP settings, open the device advanced pages > PTP Tab.

PTP Priority value :
1 is the highest priority, 255 the lowest one.
Merging devices are by default using Priority 127 when set as PTP Master and 255 when PTP slave

To modify the PTP setting, you must first tick the "Manual" checkbox.
Priority 1 is the main priority value.
Priority 2 is only used if the other parameters do not allow to elect a PTP master.
Class - Delay Mech. - Announce - Sync : those values should NOT be modified
Slave only : forces the Merging device to always be PTP slave.

Example :

To set the PTP priorities on a network :
A: Main Master priority
B: Secondary Master priority (if Main Master device fails)
C: Other devices priority

Priorities should be set as A < B < C
C should probably be 128, but as some devices may no have a manual PTP priority, it could be even lower.