ITU-T G.8271.2 (Network Limits - PTS) One-Page Summary

Title: Network limits for time synchronisation in packet networks with partial timing support from the network

Summary

• Defines the reference model for packet synchronization network assuming partial timing support

• Defines network limits at each reference point

• Describes different potential deployment scenarios for the network

Status

• Current version: 1st. Edition, October 2017, plus Amd. 1, March 2018 and Amd. 2, November 2018
• Download from: http://www.itu.int/ITU-T/recommendations/rec.aspx?rec=13324

Key Contents

Network Reference Model:

With GNSS assistance (APTS):

Without GNSS assistance (APTS):

Network Limits:

Reference points A and B:

• Max|TE| < 100ns

Reference point C, APTS:

• Peak-to-peak pktSelected2WayTE < 1100ns
• Selection window: 200s
• Selection percentage: fastest 0.25%

Reference point C, PTS:

• Maximum |pktSelected2WayTE| < 1100ns
• Selection window: 200s
• Selection percentage: fastest 0.25%

Reference point D, APTS and PTS:

• Max|TE| < 1350ns

Example Deployment Scenarios:

GNSS backup using PTP (APTS):

Bridging between two full timing support networks: