Table of Contents - G.798.3 (02/2026) - Characteristics of optical transport network hierarchy equipment functional blocks – OTU and ODU

1	Scope
2	References
3	Definitions
	3.1	Terms defined elsewhere
	3.2	Terms defined in this Recommendation
4	Abbreviations and acronyms
5	Conventions
6	Supervision
	6.1	Alarm reporting control
	6.2	Defects
	6.3	Consequent actions
	6.4	Defect correlations
	6.5	Performance filters
7	Information flow across reference points
8	Generic processes
	8.1	Alignment processes
	8.2	Signal quality supervision
	8.3	Forward error correction (FEC) processing
	8.4	Trail trace identifier (TTI) processing
	8.5	Payload structure
	8.6	Status information (STAT) acceptance process
	8.7	Maintenance signal generation and detection
	8.8	Generic layer fault processing
	8.9	OTSi modulator and demodulator processes
9	Media layer to client layer adaptation functions
	9.1	OTSi to OTUk or OTUk-RS adaptation function (OTSi/OTUk_A or OTSi/OTUkRS_A)
	9.2	OTSi to OTUkV adaptation function (OTSi/OTUkV_A)
	9.3	OTSiG to OTUk adaptation function (OTSiG/OTUk_A)
	9.4	OTSiG to OTUkV adaptation function (OTSiG/OTUkV_A)
	9.5	OTSi to OTUCn adaptation function (OTSi/OTUCn_A)
	9.6	OTSiG to OTUCn adaptation function (OTSiG/OTUCn_A)
10	OTU (layer) functions
	10.1	Connection functions
	10.2	Termination functions
	10.3	Adaptation functions
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11	ODU (layer) functions
	11.1	Connection functions
	11.2	Termination functions
	11.3	Adaptation functions
	11.4	COMMS functions
	11.5	Sublayer functions
Annex A – Optical section (OSx) and constant bit rate (CBRx) layer functions
	A.1	Connection functions
	A.2	Termination functions
	A.3	Adaptation functions
Annex B – fine grain OTN (fgOTN) layer functions
	B.1	fgODUflex Connection function (fgODUflex_C)
	B.2	fgODUflexP trail termination functions (fgODUflexP_TT)
	B.3	fgODUflex to client signals adaptation functions
	B.4	fgODUflex tandem connection sublayer (fgODUflexT) functions
	B.5	ODUkP to fgODUflex adaptation function (ODUkP/fgODUflex_A)
Appendix I – Applications and functional diagrams
	I.1	Transparent CBRx tributary interface port with optional SDH RS non-intrusive monitor on OTN equipment
	I.2	OTU tributary interface port on OTN equipment
	I.3	Selectable CBRx/OTUk tributary interface port on OTN equipment
	I.4	OTU interface ports on non-OTN equipment
	I.5	Multi-channel interface port with 3-R regeneration functionality for an ODUk connection function
Appendix II – Performance of processes
	II.1	Introduction
	II.2	OTUk frame alignment process
	II.3	STAT acceptance process and related defect detection
	II.4	OTU dIAE, OTU dBDI, ODU dBDI detection
	II.5	PT acceptance process and ODUPdPLM detection
	II.6	Generic AIS and OTUk-AIS detection
	II.7	OTU and ODUT dBIAE detection process
Appendix III – TTI processing examples
	III.1	Example 1
	III.2	Example 2
Appendix IV – Examples of compound adaptation functions
Bibliography