Using The Virtual Cable Tester - 3Com 3C2000 User Manual

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Using the Virtual Cable Tester

The Virtual Cable Tester is an optional software package that can be installed from the
3Com Master Navigator on the 3Com Installation CD.
About Marvell's Virtual Cable Tester (VCT) Technology
Marvell's Virtual Cable Tester™ (VCT) technology feature utilizes Time Domain
Reflectometry (TDR) technology to remotely and non-evasively diagnose the quality
and characteristics of the attached cables.
Using this technology, it is possible to detect and report potential cabling issues such
as cable opens, cable shorts or any impedance mismatches in the cable and
accurately report—within one meter—the distance of the fault. Additionally, VCT
technology will also detect pair swaps, pair polarity reversal and excessive pair skew.
Marvell's VCT technology enables an IT manager or an end user to quickly identify the
failing mechanism and isolate the source of the problem.
VCT lists the cable pairs, the status of the corresponding cable pair, the distance to the
fault (length), and the status of the test. If at the selected NIC the link is up, Digital
Signal Processor (DSP) is activated, which reports the speed of the connection and the
length of the cable (only if link is at Gigabit speed). VCT cannot be started if the link is
active.
The following states of a cable pair are possible after VCT is executed:
• Normal cable — the cable pair is connected correctly.
• Short cable — two or more cable pairs are short-circuited together. VCT reports
the distance to the short circuit in meters.
• Open cable — there is a lack of continuity between the pins at each end of the
twisted-pair cable. That is, the cable pair is not connected correctly. VCT reports
the distance to the open location in meters.
• Test failed — the test of the cable pairs was not successful.
• Impedance mismatch — the impedance on the cable pair is not corrected.
Possible reasons for impedance mismatch are:
• The cable pair is not connected properly.
• The cable pair is damaged.
• The connector is faulty.
VCT reports the distance to the impedance mismatch in meters.
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