EXFO FTB-800 Series for FTB-1 - Manual (Page 188)

Test Setup - Test Configurator, Timer, and System
178 FTB-700G/800 Series
RFC 2544 - Subtests

Measurement Mode, available with Dual Test Set for rates from 10M
to 10GE, allows the selection of the latency measurement mode:
Round-Trip (default) or One-Way.
Synchronization with an external 1PPS clock is required to perform
One-Way Latency measurement. One-Way Latency is only possible
when both the local and remote 1PPS signal clocks are valid. The
following alarms are available with One-Way Latency measurement
mode.
LOPPS-L and LOPPS-R (Loss Of Pulse Per Second - Local/Remote) are
declared when either no pulse is received or when no pulse is
received within 1 second ± 6.6 μs after the previous pulse. LOPPS-R is
only monitored once the DTS connection is established.

Configure per Frame Size is available when the Copy From
Throughput check box is cleared and allows to set the Max. Rate for
each frame size. For Dual Test Set the Max. Rate is configurable for
both local to remote (L -> R) and remote to local (R -> L) directions.
All Frames check box when selected (cleared by default) allows to
enter the maximum rate that will be applied to all frame sizes.