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             
        5.1     Representation of octets         
 6     Introduction             
 7     Ring protection characteristics          
        7.1     Monitoring methods and conditions   
        7.2     Ethernet traffic and bandwidth consideration 
        7.3     Ethernet ring protection switching performance           
 8     Ring protection conditions and commands  
 9     Ring protection architectures            
        9.1     Revertive and non-revertive switching              
        9.2     Protection switching triggers  
        9.3     Protection switching models on a single Ethernet ring 
        9.4     Traffic channel blocking             
        9.5     R-APS channel blocking             
        9.6     FDB flush         
        9.7     Ethernet ring protection switching models for interconnection               
10     Protection control protocol               
       10.1     Principles of operations           
       10.2     Protection switching behaviour            
       10.3     R-APS format               
       10.4     Failure of protocol defect       
Appendix I – Ring protection network objectives    
Appendix II – Ethernet ring network objectives    
Appendix III – Ring protection scenarios    
Appendix IV – Considerations for different timers    
       IV.1     State machine use of timers  
       IV.2     Guard timer use to block outdated R-APS messages   
Appendix V – Interconnected rings example     
        V.1     Configuration for interconnected rings              
        V.2     Topology examples for interconnected Ethernet rings               
Appendix VI – Protection switching for multiple ERP instances    
       VI.1     Multiple ERP instances             
       VI.2     Applying protection mechanisms to multiple ERP instances     
       VI.3     Protection switching model for multiple ERP instances              
       VI.4     Multiple instances of interconnected rings      
Appendix VII – Guidelines for the configuration of VIDs and ring IDs of R-APS channels    
      VII.1     Sub-ring with an R-APS virtual channel              
      VII.2     Sub-ring without an R-APS virtual channel       
      VII.3     Backward compatibility            
Appendix VIII – Flush optimization    
     VIII.1     Flushing FDB consideration    
     VIII.2     Scenarios of unnecessary FDB flushing             
     VIII.3     Example of FDB flush optimization     
     VIII.4     Additional definition of the ERP control process model and state machine       
     VIII.5     DNF status    
Appendix IX – Guidelines for management procedures    
       IX.1     An example procedure for removing an Ethernet ring node    
       IX.2     Management procedures to exit the FS state in case of failure of an Ethernet ring node under an FS condition    
       IX.3     Replacing an ITU-T G.8032 (2008) v1 Ethernet ring node with an ITU‑T G.8032 (2010) v2 Ethernet ring node    
Appendix X – Minimizing segmentation in interconnected rings    
        X.1     Characterization of the segmentation issue     
        X.2     Class of double faults addressed          
        X.3     Procedure for minimization of segmentation  
Appendix XI – End-to-end service resilience    
       XI.1     Generic end-to-end service resilience               
       XI.2     Layering ITU-T G.8031 protection over ITU-T G.8032    
       XI.3     Access sub-ring connected to major ring          
       XI.4     Non-ERP node connected in a major ring