EXFO IQS-8500 Series for IQS-600 - Manual (Page 317)

RFC 2544 Tabs
Ethernet and Fibre Channel Application 303
Global Configuration
Latency Measurement
Note: Available with IQS-8120NGE and IQS-8130NGE modules only in Dual Test
Set mode.
Latency Measurement Mode: Allows to select either Round-Trip (default)
or One-Way as the latency measurement mode.
To perform one-way latency measurement, the module must be
synchronized with an external 1PPS signal (refer to Clock on page 33).
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) is
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.