metrotek Bercut-MMT, Operation Manual

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10 General Information
performance evaluation.
For testing, typical frame sizes are used: 64, 128, 256, 512, 1024, 1280 and
1518 bytes, also it is possible to configure arbitrary frame size in the range
from 64 to 1518 bytes inclusive; minimum duration of each test step; frame
format (IP/UDP) and other parameters:
•
Throughput measurement allows to determine the maximum rate at
which there are no losses. Using previously obtained maximum rate
value, it is possible to determine available channel bandwidth.
•
Frame loss measurement allows to determine the percent of frames, that
were not transmitted by network element at constant load due to the
lack of hardware resources. This measurement may be useful to get in-
formation about network element behavior in case of abnormal network
loading, for example, during broadcast storm.
• Latency measurement allows to determine a time period that starts
from a moment when the last frame bit leaves transmitting side, passes
through DUT/NUT, and finishes at a moment when first bit of a frame
reaches receiving side. So this is a time required for a frame to be
transferred over network and back. Delay deviations may be a problem
in some cases, because for such protocols as VoIP, latency deviations or
its increase may result in lower voice transmission quality.
•
Back-to-back (marginal load) measurements. This test is transmission
of frames of maximum length at maximum speed, which corresponds
to minimal possible gap between frames during certain time period,
starting from idle state. Test result is quantity of frames at the longest
transmission, at which device or network under testing does not loose
any frame.
2.3 B4-GBE: Ethernet Network Analysis Card
10/100/1000 Mbit/s Ethernet network transmission parameters analysis card
(B4-GBE Card hereinafter) extends
Bercut-MMT capabilities with func-
tions of network testing on compliance to the norms, defined in RFC 2544
method and described in section 2.2, p. 9 .
The Bercut-MMT universal analyzer supports two B4-GBE cards si-
multaneously; each of them has two ports to connect to the network under
testing. Connection may be either unidirectional (for example, one port works
for data transmission (Tx), another — for data reception (Rx), Half-duplex),
or bidirectional (Tx/Rx, Full-duplex mode).
The card supports either optical or standard copper cable connection. An
SFP (Small Form Pluggable) adapter is used to connect to network interfaces;
it is plugged into B4-GBE card.
Bercut-MMT: Ethernet Networks Analysis