EXFO FTB-800 Series for FTB-1 - Manual (Page 185)

Test Setup - Test Configurator, Timer, and System
NetBlazer 175
RFC 2544 - Subtests
Back-to-Back
The objective of this test is to find the maximum number of frames that can
be sent at maximum throughput without frame loss. A burst of frames
(Burst Time) is sent with minimum inter-frame gaps to the device under
test and the number of forwarded frames is counted. If the count of
transmitted frames is equal to the number of forwarded frames, the length
of the burst is increased and the test is rerun. If the number of forwarded
frames is less than the number of transmitted frames, the length of the
burst is reduced and the test is rerun. The Back-to-Back value is the
number of frames in the longest burst that the Device Under Test (DUT)
can handle without the loss of any frames. The test performs the number of
defined trials (Trials). The Accuracy setting specifies how precise that
result must be. The test is performed for each defined frame size.

Burst Time is expressed in seconds: 1 to 5 seconds. The default setting
is 2 seconds.

Trials represents the number of times the Back-to-Back test will be
generated: 1 (default) to 100 trials.

Accuracy (Frames) is the accuracy measurement value in frames:
1 (default) to 50 frames.