EXFO FTB-8510B Guia Del Usuario página 1184

System Tab
Default Test Preferences
534
OTN (Mux Type PT20)
Allows the selection of the ODU multiplexed background traffic.
Choices are AIS, NULL Client (All Zeros), and PRBS31 pattern.
For ODU1 background traffic (ODU0 client):
The above example shows that ODU1 that contains ODU0
foreground traffic uses ODU0 background traffic.
For ODU2 background traffic (ODU1 client):
The above example shows that ODU2 that contains ODU1
foreground traffic uses ODU1 background traffic.
FTB-8100 Series Transport Blazer