EXFO FTB-800 Series for FTB-1 - Manual (Page 426)

Test Functions
416 FTB-700G/800 Series
OH - OTN
OH - OTN
From the Test menu, tap Functions, and the OH tab.
TX and RX buttons
Allows to respectively modify (TX button) the overhead information to be
transmitted or to view (RX button) the overhead information received.
Default OTN OH
Returns all TX overhead bytes to their factory default values.
TX/RX
Overhead bytes are organized using rows and columns structure as per
G.709 standard.
Row 1

OA1 and OA2, columns 1-6, OTU FAS: All the Frame Alignment Signal
OA1 bytes and OA2 bytes are individually configurable from 00 to FF.
The default values are F6 for all OA1 bytes and 28 for all OA2 bytes.

MFAS, column 7, OTU MFAS: The Multi-Frame Alignment Signal byte is
not configurable.

SM, columns 8-10, OTU OH: The Section Monitoring contains the
following bytes.
The first SM byte (column 8) contains the TTI multiframe byte that is
only configurable from Traces (OTN) on page 236.
The second SM byte (column 9) contains the BIP-8 byte that is
automatically generated for each frame. This byte is not configurable.