ITU-T G.8275.1 (PTP Profile - FTS) One-Page Summary
- Gordon Muir (Deactivated)
- Stefano Ruffini
Owned by Gordon Muir (Deactivated)
Title:Â 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
Current version: 4th Edition, November 2022Â
Download from:Â http://www.itu.int/ITU-T/recommendations/rec.aspx?rec=12815
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 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 |
Non-PRC | FALSE | TRUE | ||
T-BC in holdover, within holdover specification | 135 | PRC / PRS | TRUE | TRUE |
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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