Amendment 1
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 Network objectives
8 Protection characteristics
     8.1 Monitoring methods and conditions
9 Protection group commands
     9.1 End-to-end commands and states
     9.2 Local commands
10 Protection architectures
     10.1 Unidirectional and bidirectional switching
     10.2 Need for APS communication
     10.3 Revertive and non-revertive switching
     10.4 Provisioning mismatches
     10.5 Protection switching trigger
          10.5.1 Signal fail declaration conditions
          10.5.2 Signal degrade declaration conditions
     10.6 Protection switching models
          10.6.1 1+1 bidirectional protection switching
          10.6.2 1+1 unidirectional protection switching
          10.6.3 1:1 bidirectional protection switching
11 APS Protocol
     11.1 APS format
     11.2 1-phase APS protocol
          11.2.1 Principle of operation
          11.2.2 Revertive mode
          11.2.3 Non-revertive mode
          11.2.4 Transmission and acceptance of APS
     11.3 Request type
     11.4 Protection types and bridge type
     11.5 Requested signal
     11.6 Bridged signal
     11.7 Control of bridge
     11.8 Control of selector
     11.9 Signal fail of the protection transport entity
     11.10 Equal priority requests
     11.11 Command acceptance and retention
     11.12 Hold-off timer
     11.13 Wait-to-restore timer
     11.14 Exercise operation
     11.15 Failure of protocol defects
     11.16 Signal degrade of the protection transport entity
Annex A  State transition tables of protection switching
     A.1 State transition for 1:1 bidirectional switching with revertive mode
          A.1.1 Local requests
          A.1.2 Far-end requests
     A.2 State transition for 1:1 bidirectional switching with non-revertive mode
          A.2.1 Local requests
          A.2.2 Far-end requests
     A.3 State transition for 1+1 bidirectional switching with revertive mode
          A.3.1 Local requests
          A.3.2 Far-end requests
     A.4 State transition for 1+1 bidirectional switching with non-revertive mode
          A.4.1 Local requests
          A.4.2 Far-end requests
     A.5 State transition for 1+1 unidirectional switching with revertive mode
          A.5.1 Local requests
     A.6 State transition for 1+1 unidirectional switching with non-revertive mode
          A.6.1 Local requests
Appendix I  Operation example of 1-phase APS protocol
     I.1 Introduction
     I.2 Example scenario
          I.2.1 Revertive mode
          I.2.2 Non-revertive mode
          I.2.3 Signal fail and forced switch
     I.3 APS protocol examples
Appendix II  Interaction between Ethernet protection switching and STP
Appendix III  MIPs for protection switching environment
     III.1 Introduction
     III.2 Considerations
     III.3 Configuration examples
Appendix IV  State transition diagrams using SDL
     IV.1 Introduction
     IV.2 SDL diagrams
          IV.2.1 1:1 bidirectional protection switching
          IV.2.2 1+1 bidirectional protection switching
          IV.2.3 1+1 unidirectional protection switching