Base Unit User Guide Issue 1
Tech-X Flex™
3-4
3: 10/100 Testing Menu
Intro
Wi
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10/100
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IP/V
ideo
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3.9 Passive testing
NOTE:
Passive testing is a purchasable option. Please contact Spirent for more information.
Passive testing allows non-intrusive testing on a bridged Ethernet link. The following sections describe
passive testing and bridge setup in more detail.
3.9.1 Unit setup for passive testing
Because the two 10/100 ports are joined internally by a functional Ethernet switch, the unit is inherently
capable of bridging an Ethernet link when placed in the middle. With a bridged link, the unit can passively
monitor traffic between the ports (that is, the traffic flowing across the “bridge”), such as during a passive
measurement of video quality. The ports are always active; therefore, the bridge capability is always
active, with the monitoring feature activated when a passive test is run.
With a passive test, the unit does not send any traffic on the link, nor does it interfere with any traffic
passing through the link. However, an active link will be naturally disrupted when the unit is physically
placed in the middle. For a passive test to run, it is required that the desired traffic is activated or restored
between the bridged endpoints before the testing begins. Using the example of passive video testing,
consider the following typical setup:
Figure 3-3 Bridged (passive) video testing
To set up the video test in this example, you should:
Active video stream
ISP / IPTV
video service
Router/
gateway
Set-top box
Passive
monitoring
Ethernet
