1     Scope 
 2     References 
 3     Definitions  
        3.1     Terms defined elsewhere    
        3.2     Terms defined in this Recommendation       
 4     Abbreviations   
 5     Conventions     
 6     General      
        6.1     Packet network synchronization requirements         
        6.2     TDM timing requirements   
        6.3     Synchronization network engineering in packet networks    
        6.4     Timing requirements at edge versus timing requirements in core networks    
        6.5     PNT domain and CES domain       
 7     Reference timing signal distribution over packet networks (PNT domain)  
        7.1     Plesiochronous and network synchronous methods 
        7.2     Packet-based methods      
 8     Timing recovery for constant bit rate services transported over packet networks (CES domain)     
        8.1     Network synchronous operation    
        8.2     Differential methods           
        8.3     Adaptive methods  
        8.4     Reference clock available at the TDM end systems 
 9     Network limits  
        9.1     CES network limits
        9.2     PNT network limits
10     Impact of impairments in the packet network on timing distribution and service clock recovery     
       10.1     Packet transfer delay and delay variation   
       10.2     Impacts from packet impairments  
11     Impact of the reference clock impairment on the service clock recovery   
       11.1     Impairments for the network synchronous operation methods         
       11.2     Impairments for the differential method      
12     Results and consequences of the different synchronization methods over packet network reference models     
       12.1     CES domain recommendations     
       12.2     PNT domain recommendations     
Annex A – Proposed network architecture for synchronous Ethernet     
        A.1     PRC Location       
        A.2     Limiting jitter and wander of synchronous Ethernet 
        A.3     Considerations on the design of synchronization network based on synchronous Ethernet     
        A.4     Example of timing distribution via synchronous Ethernet      
        A.5     Interworking of Ethernet and synchronous Ethernet interfaces         
Annex B IWF functional partitioning into CES and PNT IWF and network examples     
        B.1     General  
        B.2     IWF clocks           
        B.3     Network examples
Annex C CES IWF synchronization related requirements     
        C.1     Traffic interfaces   
        C.2     Synchronization interfaces 
        C.3     IWF synchronization function        
Annex D Network applications and requirements for clocks specified in G.8262/Y.1362     
Appendix I – Characteristics of Ethernet switches and networks     
        I.1        Delay characteristics of Ethernet switches 
        I.2        Characteristics of switched Ethernet networks      
Appendix II – Stabilization period     
Appendix III Considerations on packet-based methods     
Appendix IV – Applications and use cases     
       IV.1      Background         
       IV.2     Wireless
       IV.3     Infrastructure        
       IV.4     Media gateway     
Appendix V – Packet networks reference models     
        V.1     Ethernet networks models 
        V.2     Other network models      
Appendix VI – Measurement guidelines for packet-based methods     
       VI.1     Measurement reference points       
       VI.2     Input traffic characteristics 
       VI.3     Test topologies for adaptive methods        
       VI.4     Test Topologies for differential methods    
       VI.5     Test for two-way protocols           
Appendix VII – Wander limits in Deployment Case 1     
      VII.1     Limits for the 2048 kbit/s interface
      VII.2     Limits for the 1544 kbit/s interface
Appendix VIII – Synchronization status messaging in synchronous Ethernet PHY     
Appendix IX – IWF examples     
Appendix X
Considerations on measurement of synchronous Ethernet according to ITU-T methodologies in comparison with IEEE jitter measurements     
Appendix XI Relationship between requirements contained in this Recommendation  and other key synchronization related Recommendations     
Appendix XII Basic principles of timing over packet networks     
      XII.1     General 
      XII.2     Packet delay variation mitigation by packet selection         
      XII.3     Comparison of packet-based and synchronous PHY methods       
      XII.4     Existing standards