Recommendation ITU-T G.9804.2 (09/2021) Higher speed passive optical networks – Common transmission convergence layer specification
Summary
History
FOREWORD
Table of Contents
1 Scope
     1.1 Line rate parameterization and PMD specification applicability
     1.2 Compliance
2 References
3 Definitions
     3.1 Terms defined elsewhere
     3.2 Terms defined in this Recommendation
4 Abbreviations and acronyms
5 Conventions
6 ComTC layer overview
     6.1 Supported nominal line rates
     6.2 ComTC layer structure
     6.3 ComTC sublayer functions
          6.3.1 Service adaptation sublayer
          6.3.2 Framing sublayer
          6.3.3 PHY adaptation sublayer
     6.4 Management of an HSP system
          6.4.1 Embedded OAM
          6.4.2 PLOAM channel
          6.4.3 ONU management and control channel (OMCC)
          6.4.4 ICTP
     6.5 ComTC architecture
          6.5.1 Overview
          6.5.2 ComTC identifiers
               6.5.2.1 System identifier
               6.5.2.2 PON identifier
               6.5.2.3 Downstream wavelength channel identifier
               6.5.2.4 Upstream wavelength channel identifier
               6.5.2.5 ONU identifier
               6.5.2.6 Allocation identifier
               6.5.2.7 XGEM port identifier
               6.5.2.8 Channel partition index
     6.6 Media access control
7 Resource allocation and quality of service
     7.1 Principles of downstream and upstream resource allocation
          7.1.1 Forms of traffic descriptor
          7.1.1 Traffic descriptor constraints
     7.2 Dynamic bandwidth assignment overview
          7.2.1 DBA abstraction
          7.2.2 DBA functional requirements
          7.2.3 DBA methods
          7.2.4 DBA engine
     7.3 Reference model of dynamic bandwidth assignment
          7.3.1 Summary of notation
          7.3.2 Offered traffic load
          7.3.3 Components of assigned bandwidth
          7.3.4 Guaranteed bandwidth assignment
          7.3.5 Rate-proportional assignment of additional bandwidth
          7.3.6 Additional bandwidth assignment based on priority and weights
          7.3.7 Timing control of assigned bandwidth
     7.4 DBA performance requirements
          7.4.1 Stationary bandwidth assignment
          7.4.2 Assured bandwidth restoration time
          7.4.3 DBA convergence time
     7.5 Contention-based PON operation
          7.5.1 Contention-based allocations
          7.5.2 Contention-based functions
               7.5.2.1 ONU activation
               7.5.2.2 Wavelength protection
               7.5.2.3 ONU idle support
               7.5.2.4 Watchful sleep support
          7.5.3 Collision resolution by set-splitting
               7.5.3.1 Collision resolution for contention-based allocation
               7.5.3.2 Set-splitting collision resolution protocol
               7.5.3.3 Providing collision outcome
               7.5.3.4 ONU support of the set-splitting collision resolution protocol
8 ComTC framing sublayer
     8.1 Downstream ComTC framing
          8.1.1 HLend structure
          8.1.2 BWmap partition
               8.1.2.1 Alloc-ID field
               8.1.2.2 Flags field
               8.1.2.3 StartTime field
               8.1.2.4 GrantSize field
               8.1.2.5 Forced wake-up indication (FWI) bit
               8.1.2.6 BurstProfile field
               8.1.2.7 HEC field
          8.1.3 BWmap construction and parsing rules
          8.1.4 PLOAMd partition
     8.2 Upstream ComTC framing
          8.2.1 Upstream FS header
               8.2.1.1 ONU-ID field
               8.2.1.2 Ind field
               8.2.1.3 HEC field
               8.2.1.4 Upstream PLOAM (PLOAMu) field
          8.2.2 Allocation overhead
               8.2.2.1 BufOcc field
               8.2.2.2 CRC field
          8.2.3 Upstream FS burst trailer
9 Encapsulation method
     9.1 XGEM framing
          9.1.1 FS payload structure
          9.1.2 XGEM frame header
          9.1.3 XGEM payload format
          9.1.4 Idle XGEM frame
     9.2 XGEM frame delineation
     9.3 SDU fragmentation
     9.4 Mapping of services into XGEM frames
          9.4.1 Ethernet over XGEM
          9.4.2 MPLS over XGEM
          9.4.3 Bonded XGEM
10 ComTC PHY adaptation sublayer
     10.1 Downstream PHY frame
          10.1.1 Downstream physical synchronization block (PSBd)
               10.1.1.1 Physical synchronization sequence (PSync)
               10.1.1.2 Superframe counter structure
               10.1.1.3 Operation control structure
          10.1.2 PSBd field scrambling
          10.1.3 ONU downstream synchronization
          10.1.4 Downstream PHY frame payload
     10.2 Upstream PHY frames and upstream PHY bursts
          10.2.1 Upstream physical synchronization block (PSBu)
          10.2.2 Upstream PHY burst payload
          10.2.3 Guard time
     10.3 Forward error correction
          10.3.1 Downstream FEC
               10.3.1.1 Downstream FEC codeword
               10.3.1.2 Downstream FEC control
          10.3.2 Upstream FEC
               10.3.2.1 Upstream FEC codeword
               10.3.2.2 Upstream shortened last codeword
               10.3.2.3 BWmap considerations
               10.3.2.4 Upstream FEC on/off control
     10.4 Scrambling
          10.4.1 Scrambling of the downstream PHY frame
          10.4.2 Scrambling of the upstream PHY burst
     10.5 Downstream Interleaving
          10.5.1 Interleaving of the donstream PHY frame
          10.5.2 Downstream interleaving control
11 PLOAM messaging channel
     11.1 Overview
          11.1.1 PLOAM channel functionality
          11.1.2 PLOAM channel rate limitations
          11.1.3 PLOAM channel robustness
          11.1.4 Extensibility
     11.2 PLOAM message format
          11.2.1 ONU-ID
          11.2.2 Message type ID
          11.2.3 SeqNo
          11.2.4 Message content
          11.2.5 Message integrity check
          11.2.6 Common elements of PLOAM message format
               11.2.6.1 Vendor_ID
               11.2.6.2 VSSN
               11.2.6.3 Correlation tag
               11.2.6.4 Calibration record status
               11.2.6.5 Tuning granularity
               11.2.6.6 One-step tuning time
               11.2.6.7 Attenuation
               11.2.6.8 Power levelling capability
     11.3 PLOAM message definitions
          11.3.1 Downstream PLOAM message summary
          11.3.2 Upstream PLOAM message summary
          11.3.3 Downstream PLOAM message formats
               11.3.3.1 Burst_Profile message
               11.3.3.2 Assign_ONU-ID message
               11.3.3.3 Ranging_Time message
               11.3.3.4 Deactivate_ONU-ID message
               11.3.3.5 Disable_Serial_Number message
               11.3.3.6 Request_Registration message
               11.3.3.7 Assign_Alloc-ID message
               11.3.3.8 Key_Control message
               11.3.3.9 Sleep_Allow message
               11.3.3.10 Calibration_Request message
               11.3.3.11 Adjust_Tx_Wavelength message
               11.3.3.12 Tuning_Control message
               11.3.3.13 System_Profile message
               11.3.3.14 Channel_Profile message
               11.3.3.15 Protection_Control message
               11.3.3.16 Change_Power_Level message
               11.3.3.17 Power_Consumption_Inquire message
               11.3.3.18 Reboot_ONU message
               11.3.3.19 Bonded_Channel_Status message
               11.3.3.20 Get_Set_Capabilities message
          11.3.4 Upstream PLOAM message formats
               11.3.4.1 Serial_Number_ONU message
               11.3.4.2 Registration message
               11.3.4.3 Key_Report message
               11.3.4.4 Acknowledgement message
               11.3.4.5 Sleep_Request message
               11.3.4.6 Tuning_Response message
               11.3.4.7 Power_Consumption_Report message
               11.3.4.8 Bonded_Channel_Response message
               11.3.4.9 ONU_Capabilities message
     11.4 PLOAM message operation categories
12 ONU activation cycle
     12.1 Overview
     12.2 Activation outline
     12.3 Causal sequence of activation events
     12.4 ONU activation cycle state machine
          12.4.1 States, timers, and inputs
          12.4.2 ONU state diagram
          12.4.3 ONU state transition table
     12.5 OLT support of ONU activation
     12.6 TWDM ONU power levelling
          12.6.1 ONU-activated power levelling
          12.6.2 OLT-activated power levelling
13 OLT and ONU timing relationships
     13.1 ONU transmission timing and equalization delay
          13.1.1 Timing of ONU upstream transmissions
          13.1.2 Timing relationships and quiet window during serial number acquisition
          13.1.3 Timing relationships and quiet window during ranging
          13.1.4 Calculating the equalization delay
          13.1.5 Timing relationships during operation
          13.1.6 In-service equalization delay adjustment
          13.1.7 Quiet window implementation considerations
          13.1.8 Fibre distance measurement
     13.2 Time of day distribution
          13.2.1 Notation
          13.2.2 ONU clock synchronization process
          13.2.3 Performance analysis
               13.2.3.1 Equalization delay accuracy
               13.2.3.2 Fibre propagation delay
               13.2.3.3  Internal timing corrections
14 Performance monitoring, supervision, and defects
     14.1 Performance monitoring
     14.2 Defects
          14.2.1 Items detected at OLT channel termination
          14.2.2 Items detected at ONU
          14.2.3 Urgent ONU status snapshot record
15 Security
     15.1 Threat model
     15.2 Authentication
          15.2.1 Registration-based authentication
               15.2.1.1 The OLT CT perspective
               15.2.1.2 The ONU perspective
          15.2.2 Secure mutual authentication options
     15.3 Key derivation
          15.3.1 Cryptographic method
          15.3.2 Master session key
          15.3.3 Derived shared keys
     15.4 XGEM payload encryption system
          15.4.1 Cryptographic method
          15.4.2 Secret key selection
          15.4.3 Initial counter block
     15.5 Data encryption key exchange and activation mechanism
          15.5.1 Overview
          15.5.2 Cryptographic method
          15.5.3 Unicast encryption
               15.5.3.1  Sequence of encryption key exchange and activation events
               15.5.3.2  OLT CT states and state diagram
               15.5.3.3 ONU states and state diagram
          15.5.4 Downstream multicast encryption
     15.6 Integrity protection and data origin verification for PLOAM
          15.6.1 Cryptographic method
          15.6.2 MIC calculation
     15.7 Integrity protection and data origin verification for OMCI
          15.7.1 Cryptographic method
          15.7.2 MIC calculation
     15.8 Integrity and data origin verification key switching
          15.8.1 Use of the default key
          15.8.2 Key switching for OMCI-based secure mutual authentication
          15.8.3 Key switching for IEEE 802.1x-based authentication
          15.8.4 MIC failure considerations
     15.9 HSP systems with reduced data encryption strength
          15.9.1 Effective key length
          15.9.2 Data encryption key format
16 Power management
     16.1 Power management configuration and signalling
     16.2 Power management parameter definitions
     16.3 Power management state machine specifications
          16.3.1 ONU state machine
          16.3.2 OLT CT state machine
     16.4 Management transactions in the LowPower state
     16.5 Power saving by channel selection
17 TWDM channel management
     17.1 TWDM profile announcement
          17.1.1 TWDM system and channel descriptors
          17.1.2 Profile parameter learning by ONU
     17.2 TWDM ONU calibration
          17.2.1 In-service downstream wavelength channel calibration
          17.2.2 In-service upstream wavelength channel calibration
     17.3 TWDM ONU wavelength channel handover
          17.3.1 Causal sequence of ONU handover events
          17.3.2 ONU wavelength channel handover failure conditions
          17.3.3 OLT wavelength channel handover state machine
               17.3.3.1 States, timers, inputs, and outputs
               17.3.3.2 OLT tuning state diagram
               17.3.3.3 OLT state transition table
     17.4 TWDM ONU wavelength channel locking
     17.5 Temporary suspension of a bonded wavelength channel
18 TWDM system protection
     18.1 OLT CT coordination in 1:1 Type B protection
     18.2 OLT CT Type B protection state machine
          18.2.1 States
          18.2.2 Timers
          18.2.3 Events
          18.2.4 State transition diagram
          18.2.5 State transition table
     18.3 Simplified state transition diagram
19 Rogue behaviour and its mitigation
     19.1 Rogue ONU behaviour model
     19.2 Behaviour model when coexisting with legacy ONUs
          19.2.1 Silent start at the ONU
          19.2.2 Silent start at the channel termination (OLT port)
          19.2.3 Channel termination (OLT port) detection of rogue devices
     19.3 Protection from noise and alien ONUs
     19.4 Troublesome ONU presence detection enabled through idle window
Annex A  Hybrid error control (HEC) decoding and scrambler sequence codes
Annex B  Forward error correction
     B.1 Low density parity check (LDPC) codes
          B.1.1 LDPC Coding
               B.1.1.1 Encoding operation
          B.1.2 Mother code parity check matrix
          B.1.3 Construction of LDPC(17280, 14592) codeword
Annex C  Secure mutual authentication via OMCI
Annex D  Secure mutual authentication using IEEE 802.1X
Annex E
Annex F  Tuning sequences
Annex G  Transcoded framing with FEC and OAM for PtP WDM AMCC TC
Annex H  Wavelength channel bonding
     H.1 Bonded ONU activation
Annex I  Predefined preamble patterns
     I.1 Predefined preamble patterns based on PRBSs
Appendix I  Downstream line data pattern conditioning
Appendix II  Time of day derivation and error analysis
Appendix III  Burst profiles
     III.1 Recommended seeds for preambles based on PRBSs
     III.2 Recommended PSBu structure for 12.5 Gbit/s upstream rate
Appendix IV  Golden vectors
     IV.1 50G downstream FEC codeword
     IV.2 PSBu segment preamble based on PRBSs
Appendix V  Protection examples
Appendix VI  ICTP: Inter-channel-termination protocol
Appendix VII  ONU equalization delay coordination across TWDM channels
Appendix VIII  PON-ID and system identifier examples
Appendix IX  Quiet window elimination in ONU activation
     IX.1 Scenario A: new dedicated activation wavelength (λDA)
     IX.2 Scenario B: legacy dedicated activation wavelength (λDA)
          IX.2.1 Scenario B1
          IX.2.2 Scenario B2
          IX.2.3 Scenario B3
     IX.3 Scenario C: legacy dedicated activation wavelength (λDA)
Appendix X  50G ONU synchronization state machine and transition criteria
     X.1 Transition criteria in ONU synchronization state machine
          X.1.1 State machine transitions
          X.1.2 Parameters of transitions
               X.1.2.1 Parameters of PSync Found transition (Hunt ( Pre-Sync)
               X.1.2.2 Parameters of Excessive Failure transition (Pre-Sync ( Hunt)
               X.1.2.3 Parameters of Sufficient Success transition (Pre-Sync ( Sync)
               X.1.2.4 Parameters of Failure and Excessive Failure transitions (Sync ( Re-Sync ( Hunt)
     X.2 ONU synchronization state machine
          X.2.1 PSync and SFC decoded verification
          X.2.2 PSync only verification
          X.2.3 FEC decoding
Bibliography
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