1-46
IM AQ1300-01EN
Back to Back Measurement
In the back to back measurement, the maximum burst size (number of consecutive frames) that a
network device can transmit without losing frame signals is measured. In this measurement, a burst of
frame signals (a group of consecutive frame signals) is transmitted over the specified measurement
time (the test duration).
During the test duration, if a loss is detected, the number of burst frames is automatically decreased.
The AQ1300/AQ1301 performs another measurement to detect whether a loss occurs with this new
number of burst frames. If a loss is detected, the same operations are repeated.
During the test duration, if no losses are detected, the number of burst frames is automatically
increased. The AQ1300/AQ1301 performs another measurement to detect whether a loss occurs with
this new number of burst frames. If no losses are detected, the same operations are repeated.
These operations that increase and decrease the number of burst frames are repeated until the
difference (the resolution) between the number of burst frames when a loss was detected and when no
losses were detected reaches a value that is equal to or less than the specified value.
The series of operations from the start of measurement to the point where the number of burst frames
converges to the specified value is a single measurement (a trial). The traffic rate is fixed to 100%.
Number of burst frames
Test duration
One trial
Time
Loss
No
loss Loss Loss
No
loss
No
loss
29671
14880
22320
18600 16740 17670
Resolution
Fail
Fail
Fail
Pass
Pass
Pass
The largest number of burst frames that
does not cause a loss to occur
Test Duration
This is the length of one measurement for detecting losses.
Number of Trials
The number of times that the AQ1300/AQ1301 will perform the series of operations from the start
of measurement to the point where the number of burst frames converges to the specified value.
In one trial, frame signals of the preset frame lengths are used to perform the loss detection
measurements.
The number of burst frames is the average of the values from all the trials.
Resolution
This is the range that is used to converge the back to back measurement.When the difference
between the number of burst frames when a loss was detected and when no losses were detected
falls within the resolution range, the AQ1300/AQ1301 concludes the back to back measurement.
Pass/Fail Judgment
You can perform pass/fail judgments by setting the threshold on the number of burst frames (the
lower limit on the number of frames) on the AQ1300/AQ1301 in advance.If the value falls below the
threshold, a fail judgment occurs.
1.16 RFC2544 Measurement (AQ1300 Option)
