ITU-T G.9804.2 : 2021

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

This Recommendation specifies the common transmission convergence (ComTC) layer of higher
speed passive optical network (HSP) systems, providing optical access for residential, business,
mobile backhaul, and other applications.