ITU-T Rec. G.709 (1991) � SYNCHRONOUS MULTIPLEXING STRUCTURE
FOREWORD
1 Basic multiplexing structure
2 Multiplexing method
    2.1 Multiplexing of administrative units (AUs) into STM-N
        2.1.1 Multiplexing of administrative unit groups (AUGs) into STM-N
        2.1.2 Multiplexing of AU-4s via AUG
        2.1.3 Multiplexing of AU-3s via AUG
    2.2 Multiplexing of tributary units (TUs) into VC-4 and VC-3
        2.2.1 Multiplexing of tributary unit group-3s (TUG-3s) into a VC-4
        2.2.2 Multiplexing of TU-3s via TUG-3
        2.2.3 Multiplexing of TUG-2s via TUG-3
        2.2.4 Multiplexing of TUG-2s into a VC-3
        2.2.5 Multiplexing of TU-2s via TUG-2s
        2.2.6 Multiplexing of TU-1s via TUG-2s
    2.3 Maintenance signals
        2.3.1 Section maintenance signals
        2.3.2 Path maintenance signals
    2.4 Timing recovery
3 Pointers
    3.1 AU pointer
        3.1.1 AU pointer location
        3.1.2 AU pointer value
        3.1.3 Frequency justification
        3.1.4 New data flag (NDF)
        3.1.5 Pointer generation
        3.1.6 Pointer interpretation
        3.1.7 AU-4 concatenation
    3.2 TU-3 pointer
        3.2.1 TU-3 pointer location
        3.2.2 TU-3 pointer value
        3.2.3 Frequency justification
        3.2.4 New data flag
        3.2.5 Pointer generation
        3.2.6 Pointer interpretation
    3.3 TU-1/TU-2 pointer
        3.3.1 TU-1/TU-2 pointer location
        3.3.2 TU-1/TU-2 pointer value
        3.3.3 TU-1/TU-2 multiframe indication byte
        3.3.4 TU-1/TU-2 frequency justification
        3.3.5 TU-1/TU-2 sizes
        3.3.6 New data flag (NDF)
        3.3.7 TU concatenation
        3.3.8 TU pointer generation and interpretation
4 Path overhead descriptions
    4.1 VC-3/VC-4 POH
        4.1.1 VC-3/VC-4 path trace (J1)
        4.1.2 Path BIP-8 (B3)
        4.1.3 Signal label (C2)
        4.1.4 Path status (G1)
        4.1.5 Path user channel (F2)
        4.1.6 Position indicator (H4)
        4.1.7 Spare (Z3 to Z5)
    4.2 VC-1/VC-2 POH
5 Mapping of tributaries into VCs
    5.1 Mapping of tributaries into VC-4
        5.1.1 Asynchronous mapping of 139 264 kbit/s
    5.2 Mapping of tributaries into VC-3
        5.2.1 Asynchronous mapping of 44 736 kbit/s
        5.2.2 Asynchronous mapping of 34 368 kbit/s
    5.3 Mapping of tributaries into the VC-2
        5.3.1 Byte synchronous mapping of 8448 kbit/s
        5.3.2 Asynchronous mapping of 6312 kbit/s
        5.3.3 Bit synchronous mapping of 6312 kbit/s
        5.3.4 Byte synchronous mapping of 6312 kbit/s
    5.4 Mapping of tributaries into VC-12
        5.4.1 Asynchronous mapping of 2048 kbit/s
        5.4.2 Bit synchronous mapping of 2048 kbit/s
        5.4.3 Byte synchronous mapping of 2048 kbit/s
    5.5 Mapping of tributaries into VC-11
        5.5.1 Asynchronous mapping of 1544 kbit/s
        5.5.2 Bit synchronous mapping of 1544 kbit/s
        5.5.3 Byte synchronous mapping of 1544 kbit/s
    5.6 VC-11 to VC-12 conversion for transport by a TU-12
    5.7 Floating and locked mode conversion
    5.8 Mapping of ATM cells
        5.8.1 Mapping of ATM cells into VC-4
        5.8.2 Mapping of ATM cells into other VCs
ANNEX A � Alphabetical list of abbreviations used in this Recommendation