Rec. ITU-T G.8273.2/Y.1368.2 (10/2020) Timing characteristics of telecom boundary clocks and telecom time slave clocks for use with full timing support from the network
Summary
History
FOREWORD
Table of Contents
1 Scope
2 References
3 Definitions
     3.1 Terms defined elsewhere
     3.2 Terms defined in this Recommendation
4 Abbreviations and acronyms
5 Conventions
6 Physical layer frequency performance requirements
     6.1 Synchronous equipment clock interfaces
     6.2 Enhanced synchronous equipment clock interfaces
7 T-BC packet layer performance requirements for full timing support from the network
     7.1 Time error noise generation
          7.1.1 Constant time error noise generation (cTE)
          7.1.2 Dynamic time error low-pass filtered noise generation (dTEL)
          7.1.3 Dynamic time error high-pass filtered noise generation (dTEH)
          7.1.4 Relative time error noise generation
               7.1.4.1 Relative constant time error noise generation (cTER)
               7.1.4.2 Relative dynamic time error low-pass filtered noise generation (dTERL)
     7.2 Noise tolerance
          7.2.1 Noise tolerance for clock classes A and B
          7.2.2 Noise tolerance for clock class C
     7.3 Noise transfer
          7.3.1 PTP to PTP and PTP to 1PPS noise transfer
          7.3.2 Physical layer frequency to PTP and physical layer frequency to 1PPS noise transfer for T-BC/T-TSC classes A and B
          7.3.3 Physical layer frequency to PTP and physical layer frequency to 1PPS noise transfer for T-BC/T-TSC classes C and D
     7.4 Transient response and holdover performance
          7.4.1 Transient response
               7.4.1.1 PTP output and 1PPS output transient response due to rearrangement of physical layer frequency transport and PTP network
               7.4.1.2 PTP output and 1PPS output transient response due to rearrangement of PTP network
               7.4.1.3 PTP output and 1PPS output transient response due to rearrangement of physical layer frequency transport
               7.4.1.4 PTP output and 1PPS output transient response due to long term rearrangement of physical layer frequency transport
          7.4.2 Holdover performance
               7.4.2.1 T-BC/T-TSC performance during loss of physical layer frequency assistance and loss of phase and time input reference
               7.4.2.2 T-BC/T-TSC classes A and B performance with physical layer frequency assistance during loss of PTP input reference
               7.4.2.3 T-BC/T-TSC classes C and D performance with physical layer frequency assistance during loss of PTP input reference
     7.5 Interfaces
          7.5.1 Phase and time interfaces for T-BC/T-TSC classes A and B
          7.5.2 Phase and time interfaces for T-BC/T-TSC classes C and D
          7.5.3 Frequency interfaces
Annex A  Telecom boundary clock and telecom slave clock models
Annex B  Control of the phase transient due to rearrangements in the synchronous Ethernet network
Appendix I  Mitigation of time error due to SyncE/SDH transients
Appendix II  Derivation of T-BC/T-TSC output transient mask due  to SyncE/SDH rearrangement
     II.1 Background on assumptions for and derivation of T-BC output phase error due to a SyncE/SDH rearrangement
     II.2 T-BC output phase transient mask
Appendix III  Background to performance requirements of the T-BC/T-TSC
     III.1 Noise generation requirements
     III.2 Noise tolerance
     III.3 Noise transfer
     III.4 Holdover
Appendix IV  Consideration on slave clocks embedded in end applications
Appendix V  Performance estimation for cascaded media converters acting as T-BCs  and for T-BC chains
     V.1 Noise generation
     V.2 Noise tolerance
     V.3 Noise transfer
     V.4 Transient response and holdover performance
Appendix VI  Choice of frequencies for measuring noise transfer
     VI.1 Envelope repeat frequency
     VI.2 Choice of artefact frequency
     VI.3 Possible frequencies
     VI.4 Expected filter response (PTP to PTP and PTP to 1PPS noise transfer)
     VI.5 Expected filter response (SyncE-to-PTP and SyncE-to-1PPS noise transfer)
Appendix VII  Synchronization IWF F-P node limits
Appendix VIII  Measurement of relative time error between two T-BC output ports
     VIII.1 Introduction
     VIII.2 Definition of relative time error
Bibliography