metrotek Bercut-ET, Руководство по эксплуатации

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5.2 RFC 2544 methodology 21
The test is repeated at least 20 times (user can specify alternative value
from 1 to 30).
Ta
Tb
- frame with label
Figure 5.2. Latency
3. Frame Loss Rate. This test allows to estimate network’s ability to sup-
port real-time operating applications because the big loss percentage will
result in service quality degrading.
Frame loss test allows to count the percentage of frames that have not
been transmitted by DUT due to lack of hardware resources.
To test the frame loss rate, a specific number of frames (input count)
is sent at a specific rate through the DUT to be tested and then the
analyzer counts the frames that are transmitted by the DUT (output
count). The frame loss rate at each point is calculated using the follow-
ing equation:
100
×
(
input count − output count
)
(
input count
)
The first trial should be run for the frame rate that corresponds to 100%
of the maximum rate for the frame size on the input media. Repeat the
procedure for the rate that corresponds to 90 % of the maximum rate
used and then for 80 % of this rate. The trials are continued with 10 %
reducing intervals (a finer granularity is supported) until there are two
successive trials in which no frames are lost.
Bercut-ET. Operations manual