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

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

Owned by Gordon Muir (Deactivated)
Last updated: Apr 03, 2023 by Stefano Ruffini

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

Summary

  • 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

Status

Key Contents

Profile Features:

  • 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

Clock Class Assignment:

Phase/Time Traceability DescriptiondefaultDS.clockClassInput SyncE QLFrequency Traceable FlagTime Traceable Flag
T-GM connected to a PRTC in locked mode (e.g. PRTC traceable to GNSS)6n/aTRUETRUE
T-GM in holdover, within holdover specification7PRC / PRSTRUETRUE
Non-PRCFALSETRUE
T-BC in holdover, within holdover specification135PRC / PRSTRUETRUE
Non-PRCFALSETRUE
T-GM in holdover, out of holdover specification

140PRC / PRSTRUEFALSE
150SSU-A / Stratum 2FALSEFALSE
160SSU-B / Stratum 3EFALSEFALSE
T-BC in holdover, out of holdover specification165n/aDepends on QL of input SyncE if availableFALSE
T-GM or T-BC without time reference since start-up248n/a
Slave only OC (does not send Announce messages)255n/a

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