Troubleshoot Cable with Time Domain Reflectometer (TDR) (97899)
The information in this article applies to:
- Microsoft LAN Manager 2.2
This article was previously published under Q97899 SUMMARY
A Time Domain Reflectometer (TDR) is used to troubleshoot breaks in
cabling. It measures the time between the sending of an electrical pulse
along the cable to be tested and the pulse's reflection by a potential
short or open on the cable. From this time difference, you can determine
the location of a cable break. The TDR operates at the physical layer of
the OSI layer, and is not concerned with the contents of transmitted
signals.
One end of the cable is hooked into the TDR device, and the type of cable
is chosen on the device (thin coaxial versus twisted pair, for example).
If there is a break in the cable, this will be indicated by a status
message that indicates whether the cable is "open" or "short" and at what
location (for example, "60 feet"). To maximize correct results, turn off
repeaters and bridges before attaching the TDR to the cable and connect
from the end of a segment, rather than from a "t" or tap.
Because most TDRs use a positive pulse, and transceivers do not have
positive voltage protection, it may be necessary to power down the network
while doing a TDR test. Some TDRs, however, allow tests to be performed
while the network is active.
| Modification Type: | Major | Last Reviewed: | 9/30/2003 |
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| Keywords: | KB97899 |
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