ITU-T G.8275.1 (PTP Profile - FTS) One-Page Summary

Title: PTP telecom profile for phase/time synchronization with full timing support from the network

Defines the profile (options, parameters, extensions) for the use of PTP for packet-based time/phase delivery over a network of boundary or transparent clocks
Main use-case is time synchronization of TDD-based cellular basestations

Operates directly over Ethernet using multicast messaging
Message rate 16 messages per second
Requires a BC or TC at every node in the network, with physical layer frequency support (e.g. SyncE)
Planned protection schemes in accordance with existing telecom practice
Alternate BMCA, modified from the default to allow multiple active GMs for redundancy

Phase/Time Traceability Description	defaultDS.clockClass	Input SyncE QL	Frequency Traceable Flag	Time Traceable Flag
T-GM connected to a PRTC in locked mode (e.g. PRTC traceable to GNSS)	6	n/a	TRUE	TRUE
T-GM in holdover, within holdover specification	7	PRC / PRS	TRUE	TRUE
T-GM in holdover, within holdover specification	7	Non-PRC	FALSE	TRUE
T-BC in holdover, within holdover specification	135	PRC / PRS	TRUE	TRUE
T-BC in holdover, within holdover specification	135	Non-PRC	FALSE	TRUE
T-GM in holdover, out of holdover specification	140	PRC / PRS	TRUE	FALSE
	150	SSU-A / Stratum 2	FALSE	FALSE
	160	SSU-B / Stratum 3E	FALSE	FALSE
T-BC in holdover, out of holdover specification	165	n/a	Depends on QL of input SyncE if available	FALSE
T-GM or T-BC without time reference since start-up	248	n/a
Slave only OC (does not send Announce messages)	255	n/a

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