how reliable is the tdr test?

Unanswered Question
Oct 25th, 2008

How reliable is the tdr test? I just tested several locations and they are all bad? Shouldnt I have NORMALS on all test results?

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Giuseppe Larosa Sat, 10/25/2008 - 07:49

Hello Stuart,

these results are possible all ports are running at 100 Mbps that means they don't use all the 4 pairs.

It looks like one pair is not cabled or not terminated correctly and it is always the same.

if these ports were running at 1000 Mbps and test was saying that one pair isn't usable that would be something to concern.

This because 1000 Mbps over UTP use all 4 pairs.

Older cabling was often done by saving on the wires and it is not good for GE speed.

see for example

http://www.intel.com/support/network/sb/cs-008464.htm

Hope to help

Giuseppe

scottmac Sat, 10/25/2008 - 11:40

It could also mean that whoever terminated these cables didn't follow the spec.

Are these panel-to-panel, connector-to-connector, ... i.e., what are the terminations for each of these cables?

LIke for site 4 and 6, it looks like a hand-made jumper made with a pair-pair-pair-pair configuration instead of TIA/EIA 568 pinouts. This would be a Bad Thing.

More details would be helpful, if you have 'em.

Thanks

Scott

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