EXFO FTB-8510B Guia Del Usuario página 1290

Glossary
SDH - Higher-Order Path Overhead (HP-POH)
G1: Path Status
The G1 byte provides a method to communicate the far-end path status
back to the path originating equipment.
F2: Path User Channel
The Path User Channel provides a 64 kbps channel for communication
between two PTEs. This byte is only defined for the first STM-1 frame of an
STM-N signal.
H4: Position and Sequence Indicator
The H4 byte provides a multiframe phase indication of a VC-3/4 payload to
identify phases of a SF as well as to convey the control packet information
in VCAT.
F3: Path User Channel
The Path User Channel provides a channel for communication purposes
between path elements and is payload dependent.
K3: APS Signaling
Bits 1 to 4 of the K3 byte are used for APS signaling. K3 bits 5 to 8 are
reserved for future use.
N1: Network Operator (TCM)
The N1 byte is allocated to provide a Higher-Order Tandem Connection
Monitoring (HO-TCM) function.
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FTB-8100 Series Transport Blazer